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Background: Results from an increasing number of studies suggest that mosquito excreta/feces (E/F) testing has considerable potential to serve as a supplement for traditional molecular xenomonitoring techniques. However, as the catalogue of possible use-cases for this methodology expands, and the list of amenable pathogens grows, a number of fundamental methods-based questions remain. Answering these questions is critical to maximizing the utility of this approach and to facilitating its successful implementation as an effective tool for molecular xenomonitoring.\ud Methods: Utilizing E/F produced by mosquitoes or tsetse flies experimentally exposed to Brugia malayi, Plasmodium falciparum, or Trypanosoma brucei brucei, factors such as limits of detection, throughput of testing, adaptability to use with competent- and incompetent-vector species, and effects of additional blood feedings post parasite-exposure were evaluated. Two platforms for the detection of pathogen signal (quantitative real-time PCR and digital PCR [dPCR]) were also compared, with strengths and weaknesses examined for each. \ud Results: Experimental results indicated that high throughput testing is possible when evaluating mosquito E/F for the presence of either B. malayi or P. falciparum from both competent- and incompetent-vector mosquito species. Furthermore, following exposure to pathogen, providing mosquitoes with a second, uninfected bloodmeal did not expand the temporal window for E/F collection during which pathogen detection was possible. However, this collection window did appear longer in E/F collected from tsetse flies following exposure to T. b. brucei. Testing also suggested that dPCR may facilitate detection through its increased sensitivity. Unfortunately, logistical obstacles will likely make the large-scale use of dPCR impractical for this purpose.\ud Conclusions: By examining many E/F testing variables, expansion of this technology to a field-ready platform has become increasingly feasible. However, translation of this methodology from the lab to the field will first require the completion of field-based pilot studies aimed at assessing the efficacy of E/F screening.

Monitoring vectors is relevant to ascertain transmission of lymphatic filariasis (LF). This may require the best sampling method that can capture high numbers of specific species to give indication of transmission. Gravid anophelines are good indicators for assessing transmission due to close contact with humans through blood meals. This study compared the efficiency of an Anopheles gravid trap (AGT) with other mosquito collection methods including the box and the Centres for Disease Control and Prevention gravid, light, exit and BioGent-sentinel traps, indoor resting collection (IRC) and pyrethrum spray catches across two endemic regions of Ghana. The AGT showed high trapping efficiency by collecting the highest mean number of anophelines per night in the Western (4.6) and Northern (7.3) regions compared with the outdoor collection methods. Additionally, IRC was similarly efficient in the Northern region (8.9) where vectors exhibit a high degree of endophily. AGT also showed good trapping potential for collecting Anopheles melas which is usually difficult to catch with existing methods. Screening of mosquitoes for infection showed a 0.80-3.01% Wuchereria bancrofti and 2.15-3.27% Plasmodium spp. in Anopheles gambiae. The AGT has shown to be appropriate for surveying Anopheles populations and can be useful for xenomonitoring for both LF and malaria.

Background\ud Despite the progress achieved in scaling-up mass drug administration (MDA) for lymphatic filariasis (LF) in Ghana, communities with persistent LF still exist despite over 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.\ud Methodology and principal findings\ud 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. \ud Conclusions\ud 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.

Background: Molecular xenomonitoring (MX), the testing of insect vectors for the presence of human pathogens, has the potential to provide a non-invasive and cost-effective method for monitoring the prevalence of disease within a community. Current MX methods require the capture and processing of large numbers of mosquitoes, particularly in areas of low endemicity, increasing the time, cost and labour required. Screening the excreta/feces (E/F) released from mosquitoes, rather than whole carcasses, improves the throughput by removing the need to discriminate vector species since non-vectors release ingested pathogens in E/F. It also enables larger numbers of mosquitoes to be processed per pool. However, this new screening approach requires a method of efficiently collecting E/F.\ud \ud Methods: We developed a cone with a superhydrophobic surface to allow for the efficient collection of E/F. Using mosquitoes exposed to either Plasmodium falciparum, Brugia malayi or Trypanosoma brucei brucei, we tested the performance of the superhydrophobic cone alongside two other collection methods.\ud \ud Results: All collection methods enabled the detection of DNA from the three parasites. Using the superhydrophobic cone to deposit E/F into a small tube provided the highest number of positive samples (16 out of 18) and facilitated detection of parasite DNA in E/F from individual mosquitoes. Further tests showed that following a simple washing step, the cone can be reused multiple times, further improving its cost-effectiveness.\ud \ud Conclusions: Incorporating the superhydrophobic cone into mosquito traps or holding containers could provide a simple and efficient method for collecting E/F. Where this is not possible, swabbing the container or using the washing method facilitates the detection of the three parasites used in this study.

The current mainstay for control of the four major helminth diseases in humans (lymphatic filariasis, onchocerciasis, soil-transmitted helminthiases and schistosomiasis) is with preventive chemotherapy by mass administration of key anthelminthics. Following the London Declaration on Neglected Tropical Diseases in 2012, a roadmap for the elimination and control of these helminthiases by 2020 has been devised. With expected declines in prevalence and intensity of these infections, there is urgent need for implementing more sensitive, high-throughput and cost-effective diagnostic tools. Currently available diagnostic approaches for surveying, monitoring and evaluating helminth control programmes are based on microscopical observation of eggs/larvae, and/or detection of antibodies or parasite antigens in stool, urine or blood; all relatively low-throughput and of limited sensitivity and specificity. Newly proposed approaches for helminthiases diagnosis include the nucleic acid-based methods of (multiplex) real-time polymerase chain reaction assays, loop-mediated isothermal amplification and recombinase polymerase amplification. However, as well as sensitivity/specificity evaluation, their comparison to current ‘gold standard’ diagnostics and future application in individual-/community-based diagnosis, or in xenomonitoring requires consideration of relative costs, agreement of standard methods and strategic interpretation of resulting data before control/elimination programmes might best utilize molecular diagnostics to inform decision making. We review current nucleic-acid-based molecular diagnostic methods and highlight the needs and future research required to refine these tools for monitoring and evaluation of control and elimination programmes for four major human helminthiases.

Background\ud The protozoan Giardia duodenalis is a common but highly diverse human parasite that comprises a complex of seven morphologically identical genetic assemblages, further divided into sub-assemblages. There is very little information available on the diversity of Giardia sub-assemblages and multi-locus genotypes infecting people in the United Kingdom. In this study we studied the molecular epidemiology of Giardia in symptomatic patients from North West England.\ud \ud Methods\ud Whole faecal DNA was extracted from the faecal samples of 406 Giardia cases and the parasites assemblage, sub-assemblage and multi-locus genotype were determined using PCR amplification, DNA sequencing and phylogenetic analysis of the beta-giardin, glutamate dehydrogenase, triose-phosphate isomerase and small-subunit ribosomal RNA genes. Information about age, gender and self-reported clinical outcomes was also collected from the patients to check for differences associated with the infecting Giardia assemblage.\ud \ud Results\ud Our results showed a difference in the age prevalence of the two assemblages, with assemblage A being more common in older cases. Cases infected with assemblage B more often reported vomiting and a longer illness than cases infected with assemblage A. The majority of infections (64 %) were caused by assemblage B followed by assemblage A (33 %), while mixed-assemblage infections were rare (3 %). Assemblage A isolates mostly belonged to the sub-assemblage AII and showed completed identity with previously described isolates. The level of genetic sub-structuring was significantly higher in assemblage B isolates, since a higher proportion of novel assemblage B sequences was detected compared to assemblage A. A high number of assemblage B sequences showed heterogeneous nucleotide positions that prevented the unambiguous assignment to a specific sub-assemblage. Both previously described and novel multi-locus genotypes were described in both assemblages, and up to 17 different assemblage B multi-locus genotypes were found.\ud \ud Conclusions\ud We have produced the first data on the parasite multi-locus genotypes in the UK and have demonstrated that the molecular diversity of Giardia is similar to other developed countries. Furthermore, we showed that the parasite assemblages infecting humans may be associated with patients of different ages and with different clinical outcomes.

Giardiasis, cause by the parasitic protozoan Giardia duodenalis, is one of the most common infectious gastrointestinal diseases in humans worldwide. However, its true population burden and epidemiology and in particular its zoonotic transmission potential are still poorly understood. Furthermore, G. duodenalis is not a uniform parasite but a complex of seven genetic assemblages or cryptic species (named A to G) that infect humans and a variety of domesticated and wild animals, and that can only be distinguished using molecular genotyping methods. Although there is some evidence that the two Giardia assemblages infecting humans (namely A and B) may differ in their virulence and major transmission routes, data are still scarce. In the UK, several studies suggested that giardiasis is considerably under-diagnosed and a few data are available on the genetic diversity of the parasite causing infection and disease in this country. We investigated the burden, clinical outcomes, risk factors and molecular diversity of giardiasis in North West England using both a descriptive and analytical approach. In Chapter 2, we analysed the self-reported clinical and exposure data collected over four years from clinical cases of giardiasis in Central Lancashire, as part of an enhanced surveillance program on the illness. The resulting average disease rate of 22.5 cases/100,000 population was high when compared to the available national figures. Giardiasis was particularly abundant in adults in their 30s and children under five, and the disease rate in males was significantly higher than in females. Furthermore, the clinical picture of the cases confirmed the high morbidity associated with this infection particularly in terms of the length of illness and severity of symptoms. Only 32% of the cases reported foreign travel during the exposure window. The results suggested the presence of a hidden burden of disease in adults and males, and indicated that local transmission of Giardia can be more common than expected. In Chapter 3, we performed a case-control study to determine the significant risk factors for symptomatic giardiasis in North West England, by recruiting clinical cases of Giardia and age and sex matched controls from Central and East Lancashire and Greater Manchester. The multivariable logistic regression analysis done on 118 cases and 226 controls revealed that overall travelling abroad (particularly to developing countries) was an important risk factor for the illness (OR 9.59). Following the exclusion of participants that reported foreign travel, four risk factors were significant for the acquisition of giardiasis: going to a swimming pool (OR 2.67), changing nappies (OR 3.38), suffering irritable bowel syndrome (OR 3.66) and drinking un-boiled water from the tap (OR 8.17). The results indicated the important role of swimming pools and contact with children in nappies for the transmission of the parasite. In Chapter 4, whole faecal DNA was extracted from the faecal samples of the cases part of the surveillance and case-control studies and the Giardia assemblages and sub-assemblages causing infection were determined using PCR amplification and DNA sequencing of up to four parasite genes (beta-giardin, glutamate dehydrogenase, triose-phosphate isomerase and small-subunit ribosomal RNA). The majority of infections (64%) were caused by assemblage B, followed by assemblage A (33%), whereas mixed-assemblage infections were rare (3%). The majority of the assemblage A isolates belonged to the sub-assemblage AII and showed completed identity with previously described isolates, and six multi-locus genotypes were identified. The level of genetic sub-structuring as revealed by phylogenetic analysis was significantly higher in assemblage B isolates compared with A isolates: a higher proportion of novel assemblage B sequences was detected compared to what was observed in assemblage A isolates. A high number of assemblage B sequences showed heterogeneous nucleotide positions that prevented the unambiguous assignment to a specific sub-assemblage. Up to 17 different assemblage B multi-locus genotypes were found. The molecular genotyping results showed that Giardia assemblage B was responsible for the majority of the clinical infections and confirmed the occurrence of a high diversity of parasite multi-locus genotypes. In Chapter 5, we integrated the epidemiological and the molecular data generated by the enhanced surveillance and case-control studies and we studied the clinico-epidemiological differences between cases infected with Giardia assemblage A or B. Our results showed a difference in the age prevalence between the two assemblages, with assemblage A being more common in older cases. Cases infected with assemblage B reported a series of symptoms more frequently than cases infected with assemblage A, as well as reporting a longer illness. Although the exposure profile of the cases largely overlapped between the two assemblages, two different types of exposures were reported more frequently in the two groups of cases: keeping a dog in assemblage A cases and the presence in the household of children and children at nursery in assemblage B cases. The results suggested that assemblage A could have a major zoonotic reservoir, whereas assemblage B could be transmitted more commonly via the human-to-human route.

Maximum likelihood trees of 131 bg (A), 118 gdh (B) and 136 tpi (C) sequences. The trees are based on 442, 461 and 352 aligned positions of the bg, gdh and tpi sequences respectively. One representative sequence from each identified subtype is indicated by its study ID, and the total number of isolates sharing the same sequence is reported in parentheses. Reference sequences along with the matching previously described isolates (in red for assemblage A, in blue for assemblage B) are indicated by their GenBank accession number. Optimal nucleotide substitution models: Tamura-Nei with Gamma distribution (bg), Tamura 3 parameter with Gamma distribution (gdh), Kimura 2 parameter with Gamma distribution (tpi). Only bootstrap values â Ľ70Â % for bipartitions are reported. (PDF 111Â kb)

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.