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Safety of the environment in which vegetables are grown, marketed and consumed is paramount as most are eaten raw. Irrigation sources include open drains and streams, which are often contaminated with human and animal waste due to poor sanitation infrastructure. In irrigated vegetable farms using such sources in Ghana, we assessedA cross-sectional study was conducted between January-May 2022, involving five major vegetable farms in Ghana.Lettuce was contaminated with

The modern and rapid avenue for detecting pathogens provided by molecular genetic techniques including polymerase chain reaction (PCR) was explored in the present study to identify prevalent disease pathogens, from six aquaculture farms and in two commonly cultured fish in Ghana. The specific detection was carried out directly on clinical samples of naturally infected fish (O. niloticus and C. gariepinus) based on syber-mix reaction protocol in traditional PCR. Molecular diagnostic techniques allowed the detection of the six most common and important bacterial pathogens in aquaculture farms in Ghana. Also, three of the pathogens (Streptococcus agalactiae, Streptococcus iniae, and Staphylococcus aureus) were simultaneously isolated in a multiplex reaction. The results indicated 90-100% sensitivity and specificity for each of the six bacterial pathogens tested. Streptococcosis and motile aeromonad septicemia were found to be highly prevalent in most aquaculture farms in Ghana with severity in infections traced to the 85.7% and 14.9% co-infections with all six target pathogens in catfish and tilapia respectively. The prevalence rate of infections significantly correlated with variations in salinity, conductivity, and dissolved oxygen concentrations in the thermal stressed condition of the culture water. Multiplex techniques employed in this study represent one of the first to be used by a fish health laboratory in Ghana for rapid detection of pathogens in diseased fish and could be a useful alternative to the culture-based method for routine diagnosis of fish diseases in Ghana.

This study sequenced 1077 SARS-CoV-2 genomes from patient isolates (106 from arriving travellers and 971 from communities) to track the molecular evolution and spatio-temporal dynamics of the SARS-CoV-2 variants in Ghana. The data show that initial local transmission was dominated by B.1.1 lineages, but the second wave in Ghana was overwhelmingly driven by the Alpha variant, which was detected in community cases from January 2021, with Eta also contributing to reported cases. Subsequently, an unheralded variant under monitoring, B.1.1.318, dominated transmission from April to June 2021 before being displaced by Delta (B.1.1.617) and Delta Plus (AY.*) variants, which were introduced into community transmission in May 2021 and have remained dominant to date. Mutational analysis indicated that variants that took hold in Ghana harboured transmission enhancing and immune escape spike substitutions. The apparent rapid viral evolution observed demonstrate the potential for emergence of novel variants with greater mutational fitness.

The COVID-19 pandemic is one of the fastest evolving pandemics in recent history. As such, the SARS-CoV-2 viral evolution needs to be continuously tracked. This study sequenced 1123 SARS-CoV-2 genomes from patient isolates (121 from arriving travellers and 1002 from communities) to track the molecular evolution and spatio-temporal dynamics of the SARS-CoV-2 variants in Ghana. The data show that initial local transmission was dominated by B.1.1 lineage, but the second wave was overwhelmingly driven by the Alpha variant. Subsequently, an unheralded variant under monitoring, B.1.1.318, dominated transmission from April to June 2021 before being displaced by Delta variants, which were introduced into community transmission in May 2021. Mutational analysis indicated that variants that took hold in Ghana harboured transmission enhancing and immune escape spike substitutions. The observed rapid viral evolution demonstrates the potential for emergence of novel variants with greater mutational fitness as observed in other parts of the world.

The modern and rapid avenue for detecting pathogens provided by molecular genetic techniques including polymerase chain reaction (PCR) was explored in the present study to identify prevalent disease pathogens, from six aquaculture farms and in two commonly cultured fish in Ghana. The specific detection was carried out directly on clinical samples of naturally infected fish (O. niloticus and C. gariepinus) based on syber-mix reaction protocol in traditional PCR. Molecular diagnostic techniques allowed the detection of six most common and important bacteria pathogens in aquaculture farms in Ghana. Also, three of the pathogens (Streptococcus agalactiae, Streptococcus iniae and Staphylococcus aureus) were simultaneously isolated in a multiplex reaction. The results indicated 90% - 100% sensitivity and specificity for each of the six bacterial pathogens tested. Streptococcosis and motile aeromonad septicemia were found to be highly prevalent in most aquaculture farms in Ghana with severity in infections traced to the 85.7% and 14.9% co-infections with all six target pathogens in catfish and tilapia respectively. Prevalence rate of infections significantly correlated with variations in salinity, conductivity and dissolved oxygen concentrations in the thermal stressed condition of the culture water.

Onchocerciasis is a neglected tropical disease (NTD) caused by Onchocerca Diesing 1841 (Spirurida: Onchocercidae) nematodes transmitted by blackflies. It is associated with poverty and imposes a significant health, welfare and economic burden on many tropical countries. Current methods to visualize infections within the vectors rely on invasive methods. However, using micro‐computed tomography techniques, without interference from physical tissue manipulation, we visualized in three dimensions for the first time an L1 larva of an Onchocerca species within the thoracic musculature of a blackfly, Simulium damnosum s.l. Theobald 1903 (Diptera: Simuliidae), naturally infected in Ghana. The possibility that thicker peritrophic membranes in savannah flies could account for their lower parasite loads was not supported, but there were limits to our analysis. While there were no statistically significant differences between the mean thicknesses of the peritrophic membranes, in the anterior, dorsal and ventral regions, of forest and savannah blackflies killed 34–48 min after a blood‐meal, the thickness of the peritrophic membrane in the posterior region could not be measured. Micro‐computed tomography has the potential to provide novel information on many other parasite/vector systems and impactful images for public engagement in health education., Micro‐computed tomography was used to visualize in 3D an L1 larva of an Onchocerca species within the thoracic musculature of a blackfly, Simulium damnosum s.l., naturally infected in Ghana.There were no statistically significant differences between the mean thicknesses of the peritrophic membranes of forest and savannah blackflies killed 34–48 min after a blood‐meal.Micro‐computed tomography has the potential to provide novel information on many other parasite/vector systems and impactful images for public engagement in health education.

Alzheimer's disease (AD), which is a progressive neurodegenerative disorder is the most common form of dementia globally. Several studies have suggested alteration in the gut microbiota and HSV-1 infection as contributing factors to the development of the disease. As at now, there are no AD attenuating agents and AD pharmacotherapy is focused on managing symptoms while plants used in ethnomedicine remain potential sources of drugs for the treatment of the condition. Here, we reviewed published databases for African ethnomedicinal plants and functional foods of African origin that are used in the management of AD-related phenotypes, treatment of herpes simplex virus −1 (HSV-1) and/or improvement of gut microbiota. A total of 101 unique plant species and 24 different types of traditionally prepared African functional foodstuff were identified. Of the 101 identified plant species, 50 species serve as functional foodstuffs. Twenty-three (23) of the ethnomedicinal plant families were successfully identified for the treatment and management of AD-related phenotypes and age-related dementia. Eighteen (18) African plant species from 15 families were also identified as potent remedies for HSV-1; while many African wild fruits (3 species), roots and tubers (7 species), leafy vegetables (14 species), and seaweeds (26 species) were functional foods for modifying AD-related phenotypes. It was concluded that African medicinal plants are potential sources of both AD attenuating agents and phytocompounds that may be used against HSV-1 infection and alteration of gut microbiota. Additionally, a number of African functional foods are important sources of prebiotics and probiotics.

Background Schistosomiasis remains a major public health issue with over 90% of the prevalence rates recorded in Sub-Saharan Africa. In this study, the relationships between different interleukin gene polymorphisms (IL-13-591A/G, IL-13-1055C/T, IL-13-1258A/G) and Schistosoma haematobium infection levels were evaluated; as well as the host plasma antibodies and cytokine profiles associated with schistosomiasis infection. Methodology A total of 469 school children aged 6 to 19 years from four schistosomiasis-endemic communities in Ghana were involved. Single urine and stool samples were obtained from each pupil, processed via sedimentation and Kato-Katz, and examined via microscopy for Schistosoma and soil-transmitted helminth (STH) eggs. Next, venous blood samples were drawn from 350 healthy pupils, and used to measure antibody and plasma cytokine levels by ELISA. Single nucleotide polymorphisms in the IL-13 gene were genotyped on 71 selected blood samples using the Mass Array technique. Principal findings and conclusion The overall prevalence of urinary schistosomiasis was 21.11%. Community-level prevalences were 17.12%, 32.11%, 20.80%, and 15.32% for Asempaneye, Barikumah, Eyan Akotoguah, and Apewosika respectively. Generally, higher S. haematobium infection prevalence and intensity were recorded for participants with genotypes bearing the IL13-1055C allele, the IL13-591A, and the IL13-1258A alleles. Also, higher S. haematobium infection prevalence was observed among participants in the 12-14-year age group with the IL13-1055C, IL13-591A, and IL13-1258A alleles. Interestingly, higher STH prevalence was also observed among participants with the IL13-1055C, IL13-591A, and IL13-1258A alleles. Furthermore, the age-associated trends of measured antibodies and cytokines of S. haematobium-infected school-children depicted a more pro-inflammatory immune profile for pupils aged up to 1l years, and an increasingly anti-inflammatory profile for pupils aged 12 years and above. This work provides insight into the influence of IL-13 gene polymorphisms on S. haematobium, and STH infections, in school-aged children (SAC)., Author summary Schistosomiasis is a neglected tropical disease with an estimated morbidity of 2.54 million disability-adjusted life years (DALYS), ranking it third among the parasitic diseases after Malaria and Dengue fever (WHO, 2018). About a decade ago, the World Health Organization (WHO) and its partners committed to intensifying efforts at increasing coverage during annual mass chemotherapy programmes in affected countries. This has influenced the reduction of the estimated disease-associated morbidity from 4.5 million DALYs in 2002 (WHO, 2002) to the current rate. Despite these gains, there is still growing concern that the persistent and extensive use of Praziquantel (PZQ) (the only approved chemotherapeutic agent) in these campaigns may lead to the development of poorly-responding phenotypes of Schistosoma sp. Strategies therefore to mitigate such possibilities may prove very advantageous, while research efforts towards the development of an effective vaccine continues. There has been growing evidence in recent years that infection of inhabitants in endemic areas may be influenced not only by environmental, but also by genetic factors as well. Of particular interest in this regard, is the region in the human genome, 5q31-q33, which bears several genes associated with immune function. One such group within this region is the T-helper 2 (Th2) cluster of genes, which are responsible for the production interleukin-4 (IL-4), IL-5, and IL-13 during immune response. We focused on single-nucleotide polymorphisms (SNPs) occurring in the IL-13 promoter region, particularly IL13-1055C/T, IL13-591A/G, and IL13-1258A/G, where we observed interesting trends with regard to participants’ infection status in association with the polymorphisms they presented with. Also, we assessed their immune profiles after stratifying by age, and herein indicate trends which reflect observed age-associated trends between S. haematobium infection and the IL-13 polymorphisms. The outcomes presented indicate a need for further work which challenges the current ‘one size fits all’ strategy in mass chemotherapy programmes and advocates for participant-specific/sub-group tailored programmes. This is more likely to minimize the likelihood for the development of resistant Schistosoma strains to PZQ.

Background This paper reports on the baseline prevalence and associated risk factor findings of a pilot, longitudinal study exploring community-wide treatment of schistosomiasis and soil-transmitted helminthiasis, using albendazole plus praziquantel in the Greater Accra region of Ghana. Method From three communities, at least, 658 individuals were enrolled into the study via random household selection. Prevalence and intensity of schistosomiasis and STH infection were determined from stool and urine samples with a questionnaire being administered in order to explore other morbidities and risk factors. Factor analysis of household demographic variables was undertaken to generate a socioeconomic score; this was then further categorised into tertiles. Proportional-odds cumulative logit generalised estimating equation (GEE) models were used to investigate categorical ordinal intensity of infection associations with morbidity. Separately, logistic GEE models were used to investigate risk factor associations with infection prevalence. Results Both Schistosoma haematobium and S. mansoni were prevalent in the three communities, with the prevalence of S. haematobium ranging from 3.3% (24/679; 95% CI = 1.9–4.7) to 19% (114/632; 95% CI = 15.8–22.2) and S. mansoni ranging from 30% (202/679; 95% CI = 26.5–33.5) to 78.3% (409/536; 95% CI = 74.7–81.9). The total prevalence of STH across all three sites was negligible at 1.3% (24/1847; 95% CI = 0.8–1.9) comprising mainly hookworm (10/1847). Multivariable statistical models indicated males to be 2.3 (95% CI = 1.7–3.3) times more likely to have a high intensity S. mansoni infection and 1.5 (95% CI = 1.1–2) times more likely to have a high intensity of S. haematobium infection compared to females. There was no significant difference in the likelihood of infection with S. mansoni between adults and school age children (SAC), however S. haematobium infections were found to be 2.5 (95% CI = 1.8–3.5) times more likely to occur in school age children than in adults. Multivariable statistical models (adjusted for age and sex) indicated an association between schistosomiasis and a number of self-reported morbidity indicators (notably diarrhoea and blood in stool and urine). Low socio-economic status was also associated with SCH infection (OR: 2; 95% CI = 1.3–3.2). Conclusion The communities targeted by this study showed a range of Schistosoma prevalence’s of infection, from hypo-endemic through to meso-endemic and hyper-endemic. The prevalence of SCH across the different age groups in the study locations highlights the large number of individuals currently being left out of the standard morbidity control method of annual treatment of the SAC., Author summary In this manuscript we detail the baseline results of a broader study investigating the feasibility of expanding access of albendazole and praziquantel to additional at-risk groups in three communities (Tomefa, Maheam and Torgahkope-Adakope) located around the Weija reservoir in the Greater Accra district of Ghana. Our results show that intestinal schistosomiasis was the most common form of disease across all three sites (44.2%) with Tomefa possessing the highest prevalence at 78.3%. The prevalence of urinary schistosomiasis was found to be 11.9% with the highest prevalence found in Torgahkope-Adakope (19%). STH was found to have a very low prevalence across the three communities with only 1.3% of participants found to be positive. No significant difference in STH prevalence was observed between males (0.92%; 95% CI = 0.4–1.81) and females (1.07%; 95% CI = 0.51–1.95). Statistical analysis revealed that males were more likely to be infected and to have high intensity infections of both forms of schistosomiasis. Pre-school age children (PSAC) were found to be less likely to be infected for either form of schistosomiasis in communities with low to medium prevalence of disease, however in Tomefa, where prevalence of intestinal schistosomiasis is high, there was little difference in the prevalence of disease between PSAC, school-age children (SAC) and adults. Our study shows that there is a need to treat the wider community outside of the current morbidity control strategy of mass-drug administration to SAC.

Background In Ghana, pre-school-aged children (PSAC) are at risk of intestinal schistosomiasis and are living in need of praziquantel treatment. To better assess the infection burden within this vulnerable demographic group, we have provided a comparative assessment of the prevalence of Schistosoma mansoni in pre-school-aged children by urine circulating cathodic antigen (CCA) dipsticks, real-time PCR Taqman® faecal assays and Kato-Katz coproscopy. Methods In all, 190 pre-school-aged children were sampled from three endemic communities (viz. Tomefa, Torgahkope/Adakope, and Manheam) around Weija dam, Southern Ghana. Fresh stool and urine samples were collected from all participants for diagnosis. Results Among all the three communities, the urine-CCA assay recorded the highest prevalence values of 90.5% (95% CI 80.4–96.4), 87.9% (95% CI 76.7–95), and 81.2% (95% CI 69.9–89.6) in Tomefa, Torgahkope/Adakope, and Manheam respectively. Prevalence by real-time PCR was 50% (95% CI 35.5–64.5), 8% (95% CI 2.2–19.2) and 16.7% (95% CI 8.3–28.5), while by Kato-Katz was 55.6% (95% CI 42.5–68.1), 8.6% (95% CI 2.9–19) and 11.6% (95% CI 5.1–21.6) respectively. Children aged 1 year and over were found to be positive with the urine-CCA assay; by the ages of 3–4, over 50% were urine-CCA patent. The sensitivity and specificity of the POC-CCA dipsticks, when compared against the combined results of Kato-Katz/TaqMan results was found to be 84.1% (95% CI = 72.7–92.1) and 12.9% (95% CI = 6.6–22) respectively. Conclusions We propose that the urine-CCA dipstick may be a useful rapid diagnostic tool to estimate the prevalence of intestinal schistosomiasis in PSAC, particularly in rapid identification of at-risk areas. However, our assessment has shown that it possible to record false positives when compared to combined Kato-Katz and qPCR results. To guide PSAC praziquantel treatment needs, we propose the urine CCA assay should be included in routine surveillance of intestinal schistosomiasis alongside other diagnostics such as Kato-Katz and urine filtration.

We recently developed a superhydrophobic cone-based method for the collection of mosquito excreta/feces (E/F) for the molecular xenomonitoring of vector-borne parasites showing higher throughput compared to the traditional approach. To test its field applicability, we used this platform to detect the presence of filarial and malaria parasites in two villages of Ghana and compared results to those for detection in mosquito carcasses and human blood. We compared the molecular detection of three parasites (Wuchereria bancrofti, Plasmodium falciparum and Mansonella perstans) in mosquito E/F, mosquito carcasses and human blood collected from the same households in two villages in the Savannah Region of the country. We successfully detected the parasite DNA in mosquito E/F from indoor resting mosquitoes, including W. bancrofti which had a very low community prevalence (2.5–3.8%). Detection in the E/F samples was concordant with detection in insect whole carcasses and human blood, and a parasite not vectored by mosquitoes was detected as well.Our approach to collect and test mosquito E/F successfully detected a variety of parasites at varying prevalence in the human population under field conditions, including a pathogen (M. perstans) which is not transmitted by mosquitoes. The method shows promise for further development and applicability for the early detection and surveillance of a variety of pathogens carried in human blood., Author summary Molecular xenomonitoring of parasites or viruses using mosquitoes as “flying syringes” is a promising and non-invasive tool for early detection and surveillance of various pathogens, particularly in low prevalence settings, but there is a need for cost-effective and higher throughput alternatives. We recently developed a novel approach based on the collection of mosquito excreta/feces (E/F) using a superhydrophobic cone that directs the sample into a tube at the bottom of the collection cup. We tested this method’s ability to detect the presence of filarial and malaria parasite DNA from households in two endemic rural communities of Ghana and compared it to the molecular detection from blood and mosquito carcass samples from corresponding households. The detection of parasite DNA in mosquito E/F was successful for all three pathogens, and it showed good concordance with the detection in the insects’ whole carcasses. Given the successful detection of Mansonella perstans, which is not transmitted by mosquitoes, our tool shows promise for use as an alternative method for the early and non-invasive detection and surveillance of various pathogens in human blood, including those not strictly mosquito-borne, in endemic settings.

To eliminate soil-transmitted helminth (STH) infections as a public health problem, the administration of benzimidazole (BZ) drugs to children has recently intensified. But, as drug pressure increases, the development of anthelmintic drug resistance (AR) becomes a major concern. Currently, there is no global surveillance system to monitor drug efficacy and the emergence of AR. Consequently, it is unclear what the current efficacy of the used drugs is and whether AR is already present. The aim of this study is to pilot a global surveillance system to assess anthelmintic drug efficacy and the emergence of AR in STH control programs. For this, we will incorporate drug efficacy trials into national STH control programs of eight countries (Bangladesh, Cambodia, Lao PDR, Vietnam, Ghana, Rwanda, Senegal and a yet to be defined country in the Americas). In each country, one trial will be performed in one program implementation unit to assess the efficacy of BZ drugs against STHs in school-aged children by faecal egg count reduction test. Stool samples will be collected before and after treatment with BZs for Kato-Katz analysis and preserved to purify parasite DNA. The presence and frequency of known single nucleotide polymorphisms (SNPs) in the β-tubulin genes of the different STHs will subsequently be assessed. This study will provide a global pattern of drug efficacy and emergence of AR in STH control programs. The results will provide complementary insights on the validity of known SNPs in the ß-tubulin gene as a marker for AR in human STHs as well as information on the technical and financial resources required to set up a surveillance system. Finally, the collected stool samples will be an important resource to validate different molecular technologies for the detection of AR markers or to identify novel potential molecular markers associated with AR in STH.

To eliminate soil-transmitted helminth (STH) infections as a public health problem, the administration of benzimidazole (BZ) drugs to children has recently intensified. But, as drug pressure increases, the development of anthelmintic drug resistance (AR) becomes a major concern. Currently, there is no global surveillance system to monitor drug efficacy and the emergence of AR. Consequently, it is unclear what the current efficacy of the used drugs is and whether AR is already present. The aim of this study is to pilot a global surveillance system to assess anthelmintic drug efficacy and the emergence of AR in STH control programs. For this, we will incorporate drug efficacy trials into national STH control programs of eight countries (Bangladesh, Cambodia, Lao PDR, Vietnam, Ghana, Rwanda, Senegal and a yet to be defined country in the Americas). In each country, one trial will be performed in one program implementation unit to assess the efficacy of BZ drugs against STHs in school-aged children by faecal egg count reduction test. Stool samples will be collected before and after treatment with BZs for Kato-Katz analysis and preserved to purify parasite DNA. The presence and frequency of known single nucleotide polymorphisms (SNPs) in the β-tubulin genes of the different STHs will subsequently be assessed. This study will provide a global pattern of drug efficacy and emergence of AR in STH control programs. The results will provide complementary insights on the validity of known SNPs in the ß-tubulin gene as a marker for AR in human STHs as well as information on the technical and financial resources required to set up a surveillance system. Finally, the collected stool samples will be an important resource to validate different molecular technologies for the detection of AR markers or to identify novel potential molecular markers associated with AR in STH.

BackgroundWe recently developed a superhydrophobic cone-based method for the collection of mosquito excreta/feces (E/F) for the molecular xenomonitoring of vector-borne parasites showing higher throughput compared to the traditional approach. To test its field applicability, we used this platform to detect the presence of filarial and malaria parasites in two villages of Ghana and compared results to those for detection in mosquito carcasses and human blood.Methodology and principal findingsWe compared the molecular detection of three parasites (Wuchereria bancrofti, Plasmodium falciparum and Mansonella perstans) in mosquito E/F, mosquito carcasses and human blood collected from the same households in two villages in the Savannah Region of the country. We successfully detected the parasite DNA in mosquito E/F from indoor resting mosquitoes, including W. bancrofti which had a very low community prevalence (2.5-3.8%). Detection in the E/F samples was concordant with detection in insect whole carcasses and people, and laboratory tests showed that the risk of mosquito carcass cross-contamination with positive excreta when insects are held together in the device is minimal.ConclusionsOur approach to collect and test mosquito E/F successfully detected a variety of parasites at varying prevalence in the human population under field conditions, including a pathogen (M. perstans) which is not transmitted by mosquitoes. The method shows promise for further development and applicability for the early detection and surveillance of a variety of pathogens carried in human blood.Author summaryMolecular xenomonitoring of parasites or viruses using mosquitoes as “flying syringes” is a promising and non-invasive tool for early detection and surveillance of various pathogens, particularly in low prevalence settings, but there is a need for cost-effective and higher throughput alternatives. We recently developed a novel approach based on the collection of mosquito excreta/feces (E/F) using a superhydrophobic cone that directs the sample into a tube at the bottom of the collection cup. We tested this method’s ability to detect the presence of lymphatic filariasis, malaria, and mansonellosis from households in two endemic rural communities of Ghana and compared it to the molecular detection from blood and mosquito carcass samples from corresponding households. The detection of parasite DNA in mosquito E/F was successful for all three pathogens, and it showed good concordance with the detection in the insects’ whole carcasses. Given the successful detection of Mansonella perstans, which is not transmitted by mosquitoes, our tool shows promise for use as an alternative method for the early and non-invasive detection and surveillance of various pathogens in human blood, including those not strictly mosquito-borne, in endemic settings.

With the push towards control and elimination of soil-transmitted helminthiasis and schistosomiasis in low- and middle-income countries, there is a need to develop alternative diagnostic assays that complement the current in-country resources, preferably at a lower cost. Here, we describe a novel high-resolution melt (HRM) curve assay with six PCR primer pairs, designed to sub-regions of the nuclear ribosomal locus. Used within a single reaction and dye detection channel, they are able to discriminate Ancylostoma duodenale, Necator americanus, Strongyloides stercoralis, Ascaris lumbricoides, Trichuris trichiuria and Schistosoma spp. by HRM curve analysis. Here we describe the primers and the results of a pilot assessment whereby the HRM assay was tested against a selection of archived fecal samples from Ghanaian children as characterized by Kato–Katz and real-time PCR analysis with species-specific TaqMan hydrolysis probes. The resulting sensitivity and specificity of the HRM was 80 and 98.6% respectively. We judge the assay to be appropriate in modestly equipped and resourced laboratories. This method provides a potentially cheaper alternative to the TaqMan method for laboratories in lower resource settings. However, the assay requires a more extensive assessment as the samples used were not representative of all target organisms.

Genetic diversity between and within breeds and populations of fish provides valuable information on the probable response to selection, and towards sustainable aquaculture production. However, due to the widespread introductions of O. niloticus to many regions in Africa, the genetic diversity of wild and cultured populations is now threatened. In the present study, microsatellite (SSRs) markers were used to assess genetic diversity among different Generations and cultured populations of O. niloticus in Ghana. Five Generations of a particular improved strain of O. niloticus, together with three different aquaculture populations were screened with 5sets of microsatellite primers, which produced stable and reproducible amplification and polymorphic patterns. Shannon's information index (I) values provided evidence of high genetic diversity among the Generations and the 3 cultured populations. Whereas no significant genetic differentiation (FST = 0.005), thus, structuring existed among the different Generations of the Akosombo strain, moderate genetic structuring (FST = 0.082) was found among the three different cultured population. Nei's D, phylogenetic tree analysis, also placed the AK and the two other cultured populations of O. niloticus into two different clusters, suggestive of high mixing of stocks and sharing of different genetic backgrounds. Analysis of Molecular variance (AMOVA), showed more genetic divergence existing within populations (95%), than among populations (5%). The microsatellite marker technique employed in this study was found to be a simple and efficient method for genetic diversity studies. The present study thus provides valuable base information regarding the population structure of cultured populations of O. niloticus in Ghana, which would enhance further fish population genetic studies.

In 2012, the reduction inOnchocerca volvulusinfection prevalence through long-term mass ivermectin distribution in African meso- and hyperendemic areas motivated expanding control of onchocerciasis (river blindness) as a public health problem to elimination of parasite transmission. Given the large contiguous hypo-, meso- and hyperendemic areas with an estimated population of 204 million, sustainable elimination requires an understanding of the geographic, and in turn genetic, boundaries of different parasite populations to ensure interventions are only stopped where the risk of re-introduction of the parasite through vector or human migration from areas with ongoing transmission is acceptable. These boundaries, which define the transmission zones of the parasite, may be delineated by characterising the parasite genetic population structure within and between potential zones. We analysed whole mitochondrial genome sequences of 189O. volvulusadults to determine the pattern of genetic similarity across three West African countries: Ghana, Mali, and Côte d’Ivoire. Population structure measures indicate that parasites from the Pru, Daka and Black Volta/Tombe river basins in central Ghana belong to one parasite population, showing that different river basins cannot be assumed to constitute independent transmission zones. This research forms the basis for developing tools for elimination programs to delineate transmission zones, to estimate the risk of parasite re-introduction via vector or human movement when mass ivermectin administration is stopped in one area while transmission is ongoing in others, to identify the origin of infections detected post-treatment cessation, and to investigate whether migration contributes to persisting prevalence levels during interventions.

Background Despite the progress achieved in scaling-up mass drug administration (MDA) for lymphatic filariasis (LF) in Ghana, communities with persistent LF still exist even after 10 years of community treatment. To understand the reasons for persistence, we conducted a study to assess the status of disease elimination and understand the adherence to interventions including MDA and insecticide treated nets. Methodology and principal findings We conducted a parasitological and epidemiological cross-sectional study in adults from eight villages still under MDA in the Northern Region savannah and the coastal Western Region of the country. Prevalence of filarial antigen ranged 0 to 32.4% and in five villages the prevalence of night blood microfilaria (mf) was above 1%, ranging from 0 to 5.7%. Median mf density was 67 mf/ml (range: 10–3,560). LF antigen positivity was positively associated with male sex but negatively associated with participating in MDA the previous year. Male sex was also associated with a decreased probability of participating in MDA. A stochastic model (TRANSFIL) was used to assess the expected microfilaria prevalence under different MDA coverage scenarios using historical data on one community in the Western Region. In this example, the model simulations suggested that the slow decline in mf prevalence is what we would expect given high baseline prevalence and a high correlation between MDA adherence from year to year, despite high MDA coverage. Conclusions There is a need for an integrated quantitative and qualitative research approach to identify the variations in prevalence, associated risk factors and intervention coverage and use levels between and within regions and districts. Such knowledge will help target resources and enhance surveillance to the communities most at risk and to reach the 2020 LF elimination goals in Ghana., Author summary Lymphatic filariasis (LF) is a mosquito-borne disease and a leading cause of disability and chronic morbidity worldwide. Despite the progress achieved so far in stopping LF transmission by treating the affected communities with specific drugs over several years, areas where lymphatic filariasis persists still exist. Understanding the reasons behind this is pivotal to both reach and sustain elimination. We investigated the factors associated with filariasis persistence in various communities still under drug treatment from two regions of Ghana. We reported high variability in disease burden, adherence to drug treatment and mosquito net use between regions and communities. LF infection was associated with men and not taking the drugs, and men were also less likely to take treatment. Using mathematical modelling, we showed that slight increases in treatment coverage will accelerate elimination. Our findings highlight the reasons for LF persistence and provide guidance on how to successfully achieve elimination by refining drug treatment distribution and mosquito control interventions more tailored to individuals and communities. We also demonstrated the value of using field-collected data in mathematical models to assess the current status of disease elimination and to identify the gaps in control interventions.

BackgroundWolbachia are important endosymbionts of filarial parasites. The Wolbachia of Onchocerca volvulus, the filarial pathogen responsible for the human disease onchocerciasis, is implicated in the immunopathology of the disease and may be associated with disease severity dependent on the density of Wolbachia. However, little is known in regards to the density and heterogeneity of Wolbachia in microfilariae, the life stage that is thought to be responsible for the pathology.ResultsWe used a real-time qPCR relative copy number assay to estimate the number of Wolbachia genome(s) per nuclear genome of skin microfilariae (Mf), vector L1 and iL3, and nodulectomy adult male and female O. volvulus worms sampled in Ghana and the Democratic Republic of the Congo. Relatively low median Wolbachia copy numbers and variation was observed in the Mf and vector stages, in contrast to significantly higher median and more variable Wolbachia copy number from the iL3 stage to the adult worm stages.ConclusionsThis study provides the first insight into variation in Wolbachia density between the major life stages of the parasite. The relatively invariant ratios observed for Mf and vector stages is in strong contrast to the high degree of variability of Wolbachia to nuclear ratios in adults and may indicate that the mutualistic relationship between the nematode and Wolbachia in these earlier stages is regulated differently, and certainly more stringently, than the relationship in adults.

The first 3 years of biannual ivermectin distribution in Ghana have substantially reduced Onchocerca volvulus infection levels in 10 sentinel communities, but longitudinal analysis indicates that some communities are still consistently responding suboptimally to treatment, with implications for onchocerciasis elimination., Background. Several African countries have adopted a biannual ivermectin distribution strategy in some foci to control and eliminate onchocerciasis. In 2010, the Ghana Health Service started biannual distribution to combat transmission hotspots and suboptimal responses to treatment. We assessed the epidemiological impact of the first 3 years of this strategy and quantified responses to ivermectin over 2 consecutive rounds of treatment in 10 sentinel communities. Methods. We evaluated Onchocerca volvulus community microfilarial intensity and prevalence in persons aged ≥20 years before the first, second, and fifth (or sixth) biannual treatment rounds using skin snip data from 956 participants. We used longitudinal regression modeling to estimate rates of microfilarial repopulation of the skin in a cohort of 217 participants who were followed up over the first 2 rounds of biannual treatment. Results. Biannual treatment has had a positive impact, with substantial reductions in infection intensity after 4 or 5 rounds in most communities. We identified 3 communities—all having been previously recognized as responding suboptimally to ivermectin—with statistically significantly high microfilarial repopulation rates. We did not find any clear association between microfilarial repopulation rate and the number of years of prior intervention, coverage, or the community level of infection. Conclusions. The strategy of biannual ivermectin treatment in Ghana has reduced O. volvulus microfilarial intensity and prevalence, but suboptimal responses to treatment remain evident in a number of previously and consistently implicated communities. Whether increasing the frequency of treatment will be sufficient to meet the World Health Organization's 2020 elimination goals remains uncertain.

(1) Background: Current international policy for schistosomiasis and soil-transmitted helminthiasis (STH) control emphasises mass administration of deworming drugs in school-based programmes. However, this approach is insufficient to control the transmission of these diseases, and their burden in non-school cohorts is recognised, albeit under-researched. This research will investigate the feasibility and acceptability of expanding access to praziquantel (PZQ) against schistosomiasis, and albendazole (ALB) against STH, to communities in selected transmission settings in Ghana. (2) Methods: A three-site longitudinal study will be implemented to investigate the effectiveness of expanding treatment strategies for PZQ and ALB to community members. In the context of community mass drug administration (to preschool children, school non-attending children, and adults, including pregnant women), the intervention will be assessed in a random sample of community members, at baseline with follow-up at 6, 12, and 18 months. In each community, 658 participants will be enrolled, and 314 followed up at each time point. The primary outcome measure is the prevalence of infection of Schistosoma haematobium and/or S. mansoni at study endpoint, as assessed by longitudinal surveys. Secondary outcomes are to quantify the infection of schistosomiasis and STH infections in non-treated cohorts, reductions in prevalence of STH, and intensity of schistosomiasis and STH, and treatment coverage. Nested within this study will be qualitative, cost-benefit, and cost-effectiveness evaluations that will explore accessibility, feasibility, and economic impact of expanded treatment from different complementary perspectives. (3) Discussion: Using a multidisciplinary approach, this study will generate evidence for improved availability, acceptability, affordability, and accessibility to deworming drugs against schistosomiasis and STH to individuals and communities in Ghana. This is likely to have considerable research, programmatic, and political value to contribute evidence for national programme policy development within Ghana, and, more broadly, World Health Organization policy development.

Background Wolbachia are intracellular bacteria found in arthropods and several filarial nematode species. The filarial Wolbachia have been proposed to be involved in the immunopathology associated with onchocerciasis. Higher Wolbachia-to-nematode ratios have been reported in the savannah-ecotype compared to the forest-ecotype, and have been interpreted as consistent with a correlation between Wolbachia density and disease severity. However, factors such as geographic stratification and ivermectin drug exposure can lead to significant genetic heterogeneity in the nematode host populations, so we investigated whether Wolbachia copy number variation is also associated with these underlying factors. Methods Genomic DNA was prepared from single adult nematodes representing forest and savannah ecotypes sampled from Togo, Ghana, Côte d’Ivoire and Mali. A qPCR assay was developed to measure the number of Wolbachia genome(s) per nematode genome. Next-generation sequencing (NGS) was also used to measure relative Wolbachia copy number, and independently verify the qPCR assay. Results Significant variation was observed within the forest (range: 0.02 to 452.99; median: 10.58) and savannah (range: 0.01 to 1106.25; median: 9.10) ecotypes, however, no significant difference between ecotypes (P = 0.645) was observed; rather, strongly significant Wolbachia variation was observed within and between the nine study communities analysed (P = 0.021), independent of ecotype. Analysis of ivermectin-treated and untreated nematodes by qPCR showed no correlation (P = 0.869); however, an additional analysis of a subset of the nematodes by qPCR and NGS revealed a correlation between response to ivermectin treatment and Wolbachia copy number (P = 0.020). Conclusions This study demonstrates that extensive within and between population variation exists in the Wolbachia content of individual adult O. volvulus. The origin and functional significance of such variation (up to ~ 100,000-fold between worms; ~10 to 100-fold between communities) in the context of the proposed mutualistic relationship between the worms and the bacteria, and between the presence of Wolbachia and clinical outcome of infection, remains unclear. These data do not support a correlation between Wolbachia copy number and forest or savannah ecotype, and may have implications for the development of anti-Wolbachia drugs as a macrofilaricidal treatment of onchocerciasis. The biological significance of a correlation between variation in Wolbachia copy number and ivermectin response remains unexplained. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2126-4) contains supplementary material, which is available to authorized users.

Background Treatment of onchocerciasis using mass ivermectin administration has reduced morbidity and transmission throughout Africa and Central/South America. Mass drug administration is likely to exert selection pressure on parasites, and phenotypic and genetic changes in several Onchocerca volvulus populations from Cameroon and Ghana—exposed to more than a decade of regular ivermectin treatment—have raised concern that sub-optimal responses to ivermectin's anti-fecundity effect are becoming more frequent and may spread. Methodology/Principal findings Pooled next generation sequencing (Pool-seq) was used to characterise genetic diversity within and between 108 adult female worms differing in ivermectin treatment history and response. Genome-wide analyses revealed genetic variation that significantly differentiated good responder (GR) and sub-optimal responder (SOR) parasites. These variants were not randomly distributed but clustered in ~31 quantitative trait loci (QTLs), with little overlap in putative QTL position and gene content between the two countries. Published candidate ivermectin SOR genes were largely absent in these regions; QTLs differentiating GR and SOR worms were enriched for genes in molecular pathways associated with neurotransmission, development, and stress responses. Finally, single worm genotyping demonstrated that geographic isolation and genetic change over time (in the presence of drug exposure) had a significantly greater role in shaping genetic diversity than the evolution of SOR. Conclusions/Significance This study is one of the first genome-wide association analyses in a parasitic nematode, and provides insight into the genomics of ivermectin response and population structure of O. volvulus. We argue that ivermectin response is a polygenically-determined quantitative trait (QT) whereby identical or related molecular pathways but not necessarily individual genes are likely to determine the extent of ivermectin response in different parasite populations. Furthermore, we propose that genetic drift rather than genetic selection of SOR is the underlying driver of population differentiation, which has significant implications for the emergence and potential spread of SOR within and between these parasite populations., Author summary Onchocerciasis is a human parasitic disease endemic across large areas of Sub-Saharan Africa, where more than 99% of the estimated 100 million people globally at-risk live. The microfilarial stage of Onchocerca volvulus causes pathologies ranging from mild itching to visual impairment and ultimately, irreversible blindness. Mass administration of ivermectin kills microfilariae and has an anti-fecundity effect on adult worms by temporarily inhibiting the development in utero and/or release into the skin of new microfilariae, thereby reducing morbidity and transmission. Phenotypic and genetic changes in some parasite populations that have undergone multiple ivermectin treatments in Cameroon and Ghana have raised concern that sub-optimal response to ivermectin's anti-fecundity effect may increase in frequency, reducing the impact of ivermectin-based control measures. We used next generation sequencing of small pools of parasites to define genome-wide genetic differences between phenotypically characterised good and sub-optimal responder parasites from Cameroon and Ghana, and identified multiple regions of the genome that differentiated the response types. These regions were largely different between parasites from these two countries but revealed common molecular pathways that might be involved in determining the extent of response to ivermectin's anti-fecundity effect. These data reveal a more complex than previously described pattern of genetic diversity among O. volvulus populations that differ in their geography and response to ivermectin treatment.

Ivermectin (IVM) has been in operational use for the control of onchocerciasis for two decades and remains the only drug of choice. To investigate the parasitological responses and genetic profile of Onchocerca volvulus, we carried out a 21 month epidemiological study to determine the response of the parasite to IVM in 10 Ghanaian endemic communities. Onchocerca nodules were surgically removed from patients in three IVM response categories (good, intermediate and poor) and one IVM naive community. DNA from adult worms was analyzed to determine any association between genotype and IVM response phenotypic. Embryogramme analysis showed significantly higher reproductive activity in worms from poor response communities, which had up to 41% of females with live stretched microfilaria (mf) in utero, despite IVM treatment, compared with good response communities, which had no intra-uterine stretched mf. β-tubulin isotype 1 gene has been shown to be linked to IVM selection in O. volvulus and also known to be associated with IVM resistance in veterinary nematodes. We have genotyped the full length genomic DNA sequence of the β-tubulin gene from 127 adult worms obtained from the four community categories. We found SNPs at 24 sites over the entire 3696 bp. Eight of the SNPs occurred at significantly higher (p

Schistosomiasis is a waterborne parasitic disease in sub-Saharan Africa, particularly common in rural populations living in impoverished conditions. With the scale-up of preventive chemotherapy, national campaigns will transition from morbidity- to transmission-focused interventions thus formal investigation of actual or expected declines in environmental transmission is needed as ‘end game’ scenarios arise. Surprisingly, there are no international or national guidelines to do so in sub-Saharan Africa. Our article therefore provides an introduction to key practicalities and pitfalls in the development of an appropriate environmental surveillance framework. In this context, we discuss how strategies need to be adapted and tailored to the local level to better guide and support future interventions through this transition. As detection of egg-patent infection in people becomes rare, careful sampling of schistosome larvae in freshwater and in aquatic snails with robust species-specific DNA assays will be required. Appropriate metrics, derived from observed prevalence(s) as compared with predetermined thresholds, could each provide a clearer insight into contamination- and exposure-related dynamics. Application could be twofold, first to certify areas currently free from schistosomiasis transmission or second to red-flag recalcitrant locations where extra effort or alternative interventions are needed. Electronic supplementary material The online version of this article (doi:10.1186/s40249-016-0215-9) contains supplementary material, which is available to authorized users.

BackgroundGenetic surveillance of the human filarial parasite, Onchocerca volvulus, from onchocerciasis endemic regions will ideally focus on genotyping individual infective larval stages collected from their intermediate host, Simuliid blackflies. However, blackflies also transmit other Onchocerca species, including the cattle parasite O. ochengi, which are difficult to distinguish from the human parasite based on morphological characteristics alone. This study describes a versatile approach to discriminate between O. volvulus and O. ochengi that is demonstrated using parasite infective larvae dissected from blackflies.ResultsA speciation assay was designed based on genetic differentiation between O. volvulus and O. ochengi mitochondrial genome sequences that can be performed in highthroughput high-resolution melt (HRM)- or lower throughput conventional restriction fragment length polymorphism (RFLP) analyses. This assay was validated on 185 Onchocerca larvae dissected from blackflies captured from 14 communities in Ghana throughout 2011-13. The frequency of O. ochengi was approximately 67 % of all larvae analysed, which is significantly higher than previously reported in this region. Furthermore, the species distribution was not uniform throughout the study region, with 25 %, 47 % and 93 % of O. volvulus being found in the western-most (Black Volta, Tain and Tombe), the central (Pru) and eastern-most (Daka) river basins, respectively.ConclusionsThis tool provides a simple and cost-effective approach to determine the identity and distribution of two Onchocerca species, and will be valuable for future genetic studies that focus on parasites collected from blackflies. The results presented highlight the need to discriminate Onchocerca species in transmission studies, as the frequency of each species varied significantly between the communities studied.

Accurate, simple and affordable diagnostics are needed to detect Onchocerca volvulus infection in humans. A newly developed colorimetric loop-mediated isothermal amplification (LAMP) assay was compared to PCR and skin snip analysis for diagnosis of onchocerciasis. The robustness and simplicity of the assay indicates that it may be a useful field tool for surveillance in endemic countries.

The efforts to control and eradicate polio as a global health burden have been successful to the point where currently only three countries now report endemic polio, and the number of cases of polio continues to decrease. The success of the polio programme has been dependant on a well-developed network of laboratories termed the global polio laboratory network (GPLN). Here we explore collaborative opportunities with the GPLN to target two of the 18 diseases listed as a neglected tropical diseases (NTD) namely soil transmitted helminthiasis (STH) and Schistosomiasis (SCH). These were chosen based on prevalence and the use of faecal materials to identify both polio, STH and SCH. Our study screened 448 faecal samples from the Ghana GPLN using three triplex TaqMan assays to identify Ascaris lumbricoides, Necator americanus, Ancylostoma spp, Trichuris trchiura, Strongyloides stercoralis and Schistosoma spp. Our results found a combined helminth prevalence of 22%. The most common helminth infection was A. lumbricoides with a prevalence of 15% followed by N. americanus (5%), Ancylostoma spp. (2.5%), Schistosoma spp. (1.6%) and S. stercoralis (1%). These results show that it is possible to identify alternative pathogens to polio in the samples collected by the GPLN platform and to introduce new diagnostic assays to their laboratories. The diagnostic methods employed were also able to identify S. stercoralis positive samples, which are difficult to identify using parasitological methods such as Kato-Katz. This study raises the possibility of collaboration with the GPLN for the surveillance of a wider range of diseases which would both benefit the efforts to control the NTDs and also increase the scope of the GPLN as a diagnostic platform., Author summary The successful campaign being waged against polio has eliminated the disease from most countries where it was once endemic. With this success, it is anticipated that the disease will be eradicated in the coming years with only 37 cases being reported in 2016. Although the efforts to control polio are successful there are a number of low-profile, but no less serious disease, that are still highly prevalent throughout the world. These diseases have been termed the neglected tropical diseases (NTD) and this study aims to test the suitability of the Global Polio Laboratory Network (GPLN) as a platform to screen for two of the NTDs, soil transmitted helminthiasis (STH) and schistosomiasis (SCH). To test the suitability of the samples collected by the GPLN and the suitability of the laboratories themselves 448 samples from the Ghanaian GPLN laboratory were screened with multiplex TaqMan assays for the following six helminth types: Ascaris lumbricoides, Necator americanus, Ancylostoma spp, Trichuris trchiura, Strongyloides stercoralis and Schistosoma spp. Using this method this study was able to identify a prevalence of 22% for the combined helminth infection. The most common infection was A. lumbricoides with a prevalence of 15% followed by N. americanus (5%), Ancylostoma spp. (2.5%), Schistosoma spp. (1.6%) and S. stercoralis (1%). The success of this study indicates that this may be a cost-effective method to passively screen a country for STH and SCH and its success in identifying S. stercoralis infections makes it especially useful as this parasite is hard to identify using traditional surveillance techniques.

Identification of drug resistance before it becomes a public health concern requires a clear distinction between what constitutes a normal and a suboptimal treatment response. A novel method of analyzing drug efficacy studies in human helminthiases is proposed and used to investigate recent claims of atypical responses to ivermectin in the treatment of River Blindness. The variability in the rate at which Onchocerca volvulus microfilariae repopulate host's skin following ivermectin treatment is quantified using an individual-based onchocerciasis mathematical model. The model estimates a single skin repopulation rate for every host sampled, allowing reports of suboptimal responses to be statistically compared with responses from populations with no prior exposure to ivermectin. Statistically faster rates of skin repopulation were observed in 3 Ghanaian villages (treated 12–17 times), despite the wide variability in repopulation rates observed in ivermectin-naïve populations. Another village previously thought to have high rates of skin repopulation was shown to be indistinguishable from the normal treatment response. The model is used to generate testable hypotheses to identify whether atypical rates of skin repopulation by microfilariae could result from low treatment coverage alone or provide evidence of decreased ivermectin efficacy. Further work linking phenotypic poor responses to treatment with parasite molecular genetics markers will be required to confirm drug resistance. Limitations of the skin-snipping method for estimating parasite load indicates that changes in the distribution of microfilarial repopulation rates, rather than their absolute values, maybe a more sensitive indicator of emerging ivermectin resistance.

Summary Background Ivermectin has been used for onchocerciasis control since 1987. Because of the long-term use of this drug and the development of resistance in other nematodes, we have assessed Onchocerca volvulus burdens, effectiveness of ivermectin as a microfilaricide, and its effect on adult female worm reproduction. Methods For the first phase of the study, 2501 individuals in Ghana, from 19 endemic communities who had received six to 18 annual rounds of ivermectin and one ivermectin naive community, were assessed for microfilarial loads 7 days before the 2004 yearly ivermectin treatment, by means of skin snips, and 30 days after treatment to assess the ivermectin microfilaricidal action. For the second phase, skin snips were taken from 342 individuals from ten communities, who were microfilaria positive at pretreatment assessment, on days 90 and 180 after treatment, to identify the effects of ivermectin on female worm fertility, assessed by microfilaria repopulation. Findings 487 (19%) of the 2501 participants were microfilaria positive. The microfilaria prevalence and community microfilarial load in treated communities ranged from 2·2% to 51·8%, and 0·06 microfilariae per snip to 2·85 microfilariae per snip, respectively. Despite treatment, the prevalence rate doubled between 2000 and 2005 in two communities. Microfilaria assessment 30 days after ivermectin treatment showed 100% clearance of microfilaria in more than 99% of people. At day 90 after treatment, four of ten communities had significant microfilaria repopulation, from 7·1% to 21·1% of pretreatment counts, rising to 53·9% by day 180. Interpretation Ivermectin remains a potent microfilaricide. However, our results suggest that resistant adult parasite populations, which are not responding as expected to ivermectin, are emerging. A high rate of repopulation of skin with microfilariae will allow parasite transmission, possibly with ivermectin-resistant O volvulus , which could eventually lead to recrudescence of the disease.

Development times of eggs, larvae and pupae of vectors of onchocerciasis ( Simulium spp.) and of Onchocerca volvulus larvae within the adult females of the vectors decrease with increasing temperature. At and above 25°C, the parasite could reach its infective stage in less than 7 days when vectors could transmit after only two gonotrophic cycles. After incorporating exponential functions for vector development into a novel blackfly population model, it was predicted that fly numbers in Liberia and Ghana would peak at air temperatures of 29°C and 34°C, about 3°C and 7°C above current monthly averages, respectively; parous rates of forest flies (Liberia) would peak at 29°C and of savannah flies (Ghana) at 30°C. Small temperature increases (less than 2°C) might lead to changes in geographical distributions of different vector taxa. When the new model was linked to an existing framework for the population dynamics of onchocerciasis in humans and vectors, transmission rates and worm loads were projected to increase with temperature to at least 33°C. By contrast, analyses of field data on forest flies in Liberia and savannah flies in Ghana, in relation to regional climate change predictions, suggested, on the basis of simple regressions, that 13–41% decreases in fly numbers would be expected between the present and before 2040. Further research is needed to reconcile these conflicting conclusions.

Background The World Health Organization (WHO) aims at eliminating onchocerciasis by 2020 in selected African countries. Current control focuses on community-directed treatment with ivermectin (CDTI). In Ghana, persistent transmission has been reported despite long-term control. We present spatial and temporal patterns of onchocerciasis transmission in relation to ivermectin treatment history. Methodology/Principal Findings Host-seeking and ovipositing blackflies were collected from seven villages in four regions of Ghana with 3–24 years of CDTI at the time of sampling. A total of 16,443 flies was analysed for infection; 5,812 (35.3%) were dissected for parity (26.9% parous). Heads and thoraces of 12,196 flies were dissected for Onchocerca spp. and DNA from 11,122 abdomens was amplified using Onchocerca primers. A total of 463 larvae (0.03 larvae/fly) from 97 (0.6%) infected and 62 (0.4%) infective flies was recorded; 258 abdomens (2.3%) were positive for Onchocerca DNA. Infections (all were O. volvulus) were more likely to be detected in ovipositing flies. Transmission occurred, mostly in the wet season, at Gyankobaa and Bosomase, with transmission potentials of, respectively, 86 and 422 L3/person/month after 3 and 6 years of CDTI. The numbers of L3/1,000 parous flies at these villages were over 100 times the WHO threshold of one L3/1,000 for transmission control. Vector species influenced transmission parameters. At Asubende, the number of L3/1,000 ovipositing flies (1.4, 95% CI = 0–4) also just exceeded the threshold despite extensive vector control and 24 years of ivermectin distribution, but there were no infective larvae in host-seeking flies. Conclusions/Significance Despite repeated ivermectin treatment, evidence of O. volvulus transmission was documented in all seven villages and above the WHO threshold in two. Vector species influences transmission through biting and parous rates and vector competence, and should be included in transmission models. Oviposition traps could augment vector collector methods for monitoring and surveillance., Author Summary The World Health Organization (WHO) aims at eliminating onchocerciasis by 2020 in selected African countries. The success of elimination using ivermectin treatment alone will depend on several interacting factors including baseline endemicity, treatment coverage and vector species mix. In Ghana, transmission persists despite prolonged control. We investigated entomological determinants of this persistence. Blackflies were collected from seven villages with 3–24 years of ivermectin treatment. A total of 12,196 flies was dissected, with 463 larvae (all Onchocerca volvulus) in 97 infected and 62 infective flies. Transmission indices in the wet season, at Gyankobaa and Bosomase, amounted to, respectively, 86 and 422 infective larvae/person/month after 3 and 6 years of ivermectin treatment. Infection levels at these villages were over 100 times the WHO threshold of one L3/1,000 parous flies. At Asubende, an infective fly was caught among ovipositing flies in nearby breeding sites, indicating that infection was just over the WHO threshold despite extensive ivermectin and vector control. Spatial and seasonal vector species composition influences the magnitude of transmission indices through variations in biting and parous rates, and vectorial competence and capacity, and should be reflected in transmission models. Oviposition traps could enhance vector collection for transmission monitoring and surveillance.

Ivermectin resistance is common in trichostrongylid nematodes of livestock, such as Haemonchus contortus. This anthelmintic is the only drug approved for mass administration to control onchocerciasis caused by the nematode parasite, Onchocerca volvulus. In parts of West Africa up to 18 rounds of ivermectin treatment have been administered to communities and there are reports of poor parasitological responses to treatment. Understanding ivermectin resistance and ivermectin selection is an important step to reduce selection pressure for resistance, and to develop molecular markers which can be used to monitor the development of resistance and its spread. Here we report evidence that ivermectin selection changes the frequency of beta-tubulin alleles in both the sheep parasite, H. contortus, and the human parasite, O. volvulus. In O. volvulus we have been able to look at the frequency of beta-tubulin alleles in O. volvulus obtained before any ivermectin was used in humans in Africa, and following its widespread use. In H. contortus, we have been able to look at the frequency of beta-tubulin alleles in a strain which has not seen any anthelmintic selection and in an ivermectin selected strain derived from the unselected strain. We have found ivermectin selects on beta-tubulin in both of these nematode species. In the case of O. volvulus, we had previously reported that ivermectin selects for specific single nucleotide polymorphisms in the O. volvulus beta-tubulin gene. This polymorphism results in three amino acid changes in the H3 helix of beta-tubulin, as well as deletions in an associated intron. We report a simple PCR assay to detect the amplicon length polymorphism, resulting from these intronic deletions, which can be used to monitor the frequency of the beta-tubulin allele selected for by ivermectin in O. volvulus.

Onchocerciasis is a debilitating neglected tropical disease caused by infection with the filarial parasite Onchocerca volvulus. Adult worms live in subcutaneous tissues and produce large numbers of microfilariae that migrate to the skin and eyes. The disease is spread by black flies of the genus Simulium following ingestion of microfilariae that develop into infective stage larvae in the insect. Currently, transmission is monitored by capture and dissection of black flies and microscopic examination of parasites, or using the polymerase chain reaction to determine the presence of parasite DNA in pools of black flies. In this study we identified a new DNA biomarker, encoding O. volvulus glutathione S-transferase 1a (OvGST1a), to detect O. volvulus infection in vector black flies. We developed an OvGST1a-based loop-mediated isothermal amplification (LAMP) assay where amplification of specific target DNA is detectable using turbidity or by a hydroxy naphthol blue color change. The results indicated that the assay is sensitive and rapid, capable of detecting DNA equivalent to less than one microfilaria within 60 minutes. The test is highly specific for the human parasite, as no cross-reaction was detected using DNA from the closely related and sympatric cattle parasite Onchocerca ochengi. The test has the potential to be developed further as a field tool for use in the surveillance of transmission before and after implementation of mass drug administration programs for onchocerciasis.

Background The lymphatic filariasis (LF) control programme has been on-going in Ghana since 2000 with mass drug administration (MDA) of ivermectin (IVM) and albendazole (ALB). Soil-transmitted helminth (STH) infections control is augmented within this programme. Therefore this study aimed to determine the efficacy of ALB against STH infections and impact of MDA on study participants. Methods This was a twelve months longitudinal study. A total of 412 subjects including school children (between the ages of 2–17 years) and pregnant women were randomly selected from four endemic communities in Kpandai district of the Northern region. Coprological assessment for parasites was based on the Kato–Katz technique in both dry and rainy seasons at baseline, 21 days and 3 months post treatment. Single dose albendazole treatment was administered to all patients at baseline. Results Of all the parasites found (hookworm, Trichuris trichiura, Hymenolepis nana, and Taenia sp.), hookworm was the most prevalent. In the dry season, the overall STHs prevalence at pre-treatment was 29%, while 9% and 13% prevalence was recorded at 21 days, and three months after treatment, respectively. However, in the rainy season, the overall STHs prevalence was 8%, while 4% and 12% was recorded at 21 days and three months respectively after ALB treatment. In general, ALB treatment resulted in an overall hookworm egg count reduction rate of 89% in the dry season and 93% in the rainy season, while the T. trichiura egg count reduction rate was 100% in both seasons. Conclusions STH infections still remain a significant public health burden in Ghana. Hookworm infection seems to respond poorly or suboptimally to ALB, raising concerns of possible emergence of resistance which may lead to a major setback for the control and elimination of STH infections, especially hookworm infections.

Sub-optimal responses to ivermectin (IVM) have emerged. Targeting the Onchocerca volvulus Wolbachia endosymbionts with doxycycline is effective in clearing microfilariae in onchocerciasis patients with persistent microfilaridermia and in enhanced killing of adult worms after repeated standard IVM treatment., Background. Ivermectin (IVM) has been the drug of choice for the treatment of onchocerciasis. However, there have been reports of persistent microfilaridermia in individuals from an endemic area in Ghana after many rounds of IVM, raising concerns of suboptimal response or even the emergence of drug resistance. Because it is considered risky to continue relying only on IVM to combat this phenomenon, we assessed the effect of targeting the Onchocerca volvulus Wolbachia endosymbionts with doxycycline for these individuals with suboptimal response. Methods. One hundred sixty-seven patients, most of them with multiple rounds of IVM, were recruited in areas with IVM suboptimal response and treated with 100 mg/day doxycycline for 6 weeks. Three and 12 months after doxycycline treatment, patients took part in standard IVM treatment. Results. At 20 months after treatment, 80% of living female worms from the placebo group were Wolbachia positive, whereas only 5.1% in the doxycycline-treated group contained bacteria. Consistent with interruption of embryogenesis, none of the nodules removed from doxycycline-treated patients contained microfilariae, and 97% of those patients were without microfilaridermia, in contrast to placebo patients who remained at pretreatment levels (P < .001). Moreover, a significantly enhanced number of dead worms were observed after doxycycline. Conclusions. Targeting the Wolbachia in O. volvulus is effective in clearing microfilariae in the skin of onchocerciasis patients with persistent microfilaridermia and in enhanced killing of adult worms after repeated standard IVM treatment. Strategies can now be developed that include doxycycline to control onchocerciasis in areas where infections persist despite the frequent use of IVM. Clinical Trials Registration. ISRCTN 66649839.