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The health security planning process transforms recommendations from various evaluations into priority actions to strengthen countries' capacity for emergency preparedness using the One Health approach. Although the World Health Organization (WHO) has developed many tools to facilitate the planning process of a National Action Plan for Health Security (NAPHS) across the various components, a series of multisectoral workshops is still needed to complete the process. In this article, we report on the process of developing Cameroon's NAPHS and propose an innovative solution to improve the process. The NAPHS development process was conducted from May to December 2018. The WHO NAPHS framework, adapted to the local context, guided the process. The WHO planning matrix was used to plan activities and the WHO NAPHS costing tool was used to facilitate the costing exercise. A total of 84 Joint External Evaluation recommendations were translated into activities included in Cameroon's NAPHS. Among these activities, the majority (56%) were of medium priority. The total cost of a 5-year NAPHS was US$87,668,356, with almost half (49%) of the budget allocated to activities in the "Prevent" category and more than a third (35%) allocated to the "Detect" category. The top 3 cost drivers were immunization (22%), the national laboratory system (21%), and antimicrobial resistance (16%). The NAPHS informed policymakers of planned activities and funding needs to fast-track the development of health security capacities. Running gaps in funding will be addressed during a resource mapping exercise. To improve the overall planning process, a web-based support solution, where stakeholders select from a menu of recommendations from the Joint External Evaluation to develop a NAPHS, should be developed to improve the NAPHS development process.

BackgroundAlthough “Slash and Clear” has proven effective in reducing blackfly densities in low transmission foci, the impact of this strategy in high transmission settings with large rivers and important vector densities remains to be demonstrated.Methods/Principal findingsA controlled before-and-after community-based intervention comprising two arms (Bayomen as control site and Biatsota as intervention site) was carried out in the Mbam Valley (Centre Region, Cameroon). In each arm, baseline blackfly densities were collected over one year using the human landing method. The intervention consisted of destroying the trailing vegetation where blackflies breed. Blackfly densities were collected post-intervention to assess the impact of the intervention. Before the intervention, a total of 36,273 and 29,041 blackflies were collected in Bayomen and Biatsota, respectively. After the intervention period, the total blackfly density in the intervention site decreased from 29,041 to 20,011 (31.1% reduction), while an increase of 2·7% was observed in the control site (from 36,273 to 37,248). The Poisson mixed regression model shows that the reduction was significantly greater in the intervention site than in the control site (pConclusions/SignificanceThis study showed that “Slash and Clear” approach is feasible and has a significant impact on vector densities in a high transmission setting. Further studies are needed to investigate the long-term impact of this vector control approach, and how this promising strategy can be scaled-up and sustained until elimination of onchocerciasis.Author summaryRiver blindness persists in some foci in Cameroon despite more than two decades of ivermectin-based preventive chemotherapy. Mass drug administration (MDA) appears insufficient to interrupt onchocerciasis transmission in these hotspots, and should be complemented by vector control, the most promising alternative strategy to date. In 2018, the effectiveness of a new community-based vector control approach, known as slash and clear, was demonstrated. This strategy involves the removal of trailing vegetation at breeding sites, a primary attachment points for blackfly larvae. In this study, we show that this environment-friendly intervention is feasible and has a significant impact on blackfly densities in high transmission settings. This promising intervention can be combined with regular annual ivermectin-based preventive chemotherapy to accelerate onchocerciasis elimination.

Background The reduction of the contacts between humans and blackflies can lead to the interruption of the onchocerciasis transmission. Esperanza window trap (EWT) has been shown to be effective in reducing blackfly densities. Several shape-based improvements to this trapping system have been developed to optimize its performance. However, the optimisation of this trapping system has always been based on the shape of the trap, high blackfly density areas or on the addition of attractants, without considering transmission potentials and parity rates. This study aims to investigate the differences in biting rates and transmission potential between three catching points to guide the choice of EWT placement. Methods Monthly blackfly collection was carried out over one year using human landing method at three catching points along a transect from riverside toward the centre of two first-line villages (Biatsota and Bayomen) of the Mbam valley in Cameroon. Female blackflies caught were counted and dissected, and entomological indicators were computed and compared between catching points and villages. Results A total of 80,732 blackflies were caught and 57,517 dissected, of which 2,743 (4.8%) were parous and 44 (1.6%) infective. Regarding the distance to the river, a vector density gradient was observed, the highest annual biting rates (ABRs) being recorded at riverside. Furthermore, the highest annual transmission potentials were also recorded at riversides (165 vs 255 Infective larvae/man/year in Bayomen and Biatsota, respectively). Globally, the highest parity rates (PR) were recorded at the riverside in Biatsota (5.1%) where various human activities are frequent, and at the centre of the village in Bayomen (6.3%). Conclusion This study reveals that entomological parameters were the highest at riversides and indicates that EWTs or other trapping systems should be set up in priority at riverside for optimal performance in onchocerciasis control.

Background Mass drug administration (MDA) with ivermectin is the main strategy for onchocerciasis elimination. Ivermectin is generally safe, but is associated with serious adverse events in individuals with high Loa loa microfilarial densities (MFD). Therefore, ivermectin MDA is not recommended in areas where onchocerciasis is hypo-endemic and L loa is co-endemic. To eliminate onchocerciasis in those areas, a test-and-not-treat (TaNT) strategy has been proposed. We investigated whether onchocerciasis elimination can be achieved using TaNT and the required duration. Methods We used the individual-based model ONCHOSIM to predict the impact of TaNT on onchocerciasis microfilarial (mf) prevalence. We simulated precontrol mf prevalence levels from 2% to 40%. The impact of TaNT was simulated under varying levels of participation, systematic nonparticipation, and exclusion from ivermectin resulting from high L loa MFD. For each scenario, we assessed the time to elimination, defined as bringing onchocerciasis mf prevalence below 1.4%. Results In areas with 30% to 40% precontrol mf prevalence, the model predicted that it would take between 14 and 16 years to bring the mf prevalence below 1.4% using conventional MDA, assuming 65% participation. TaNT would increase the time to elimination by up to 1.5 years, depending on the level of systematic nonparticipation and the exclusion rate. At lower exclusion rates (≤2.5%), the delay would be less than 6 months. Conclusions Our model predicts that onchocerciasis can be eliminated using TaNT in L loa co-endemic areas. The required treatment duration using TaNT would be only slightly longer than in areas with conventional MDA, provided that participation is good., Our model predicts that onchocerciasis can be eliminated using test-and-not-treat (TaNT) in L loa co-endemic areas. The required treatment duration using TaNT would be only slightly longer than in areas with conventional mass drug administration, provided that participation is good.

Background The diagnostic gold standard for onchocerciasis relies on identification and enumeration of (skin-dwelling) Onchocerca volvulus microfilariae (mf) using the skin snip technique (SST). In a recent study, blood-borne Loa loa mf were found by SST in individuals heavily infected with L. loa, and microscopically misidentified as O. volvulus due to their superficially similar morphology. This study investigates the relationship between L. loa microfilarial density (Loa MFD) and the probability of testing SST positive. Methods A total of 1053 participants from the (onchocerciasis and loiasis coendemic) East Region in Cameroon were tested for (1) Loa MFD in blood samples, (2) O. volvulus presence by SST, and (3) Immunoglobulin (Ig) G4 antibody positivity to Ov16 by rapid diagnostic test (RDT). A Classification and Regression Tree (CART) model was used to perform a supervised classification of SST status and identify a Loa MFD threshold above which it is highly likely to find L. loa mf in skin snips. Results Of 1011 Ov16-negative individuals, 28 (2.8%) tested SST positive and 150 (14.8%) were L. loa positive. The range of Loa MFD was 0–85 200 mf/mL. The CART model subdivided the sample into 2 Loa MFD classes with a discrimination threshold of 4080 (95% CI, 2180–12 240) mf/mL. The probability of being SST positive exceeded 27% when Loa MFD was >4080 mf/mL. Conclusions The probability of finding L. loa mf by SST increases significantly with Loa MFD. Skin-snip polymerase chain reaction would be useful when monitoring onchocerciasis prevalence by SST in onchocerciasis–loiasis coendemic areas.

Socio-economic and socio-demographic factors have been considered as critical in disease epidemiology and need to be taken into consideration when designing health interventions. It is therefore strongly recommended to investigate population ownership to ensure sustainability of a given intervention. To this end, a household-based cross sectional survey was conducted to assess knowledge and perceptions regarding sleeping sickness and its control among populations of the four epicenter villages (Lambi, Bidjouka, Memel 1, and Ebimimbang) of the Bipindi sleeping sickness focus (South Region, Cameroon). It was found that the population of Bipindi is stable (64.0% of participants having spent on average 22 years in this focus), with high education level (64.8% having reached at least the secondary level). Overall, 92.8% (95% CI: 86.9-96.2) of the participants were aware of sleeping sickness or Human Africa Trypanosomiasis (HAT) and 68.3% (95% CI: 59.6-75.9) have been in contact with people who had suffered from this disease. Males had better knowledge of sleeping sickness clinical signs and mode of transmission than their female counterparts. Knowledge was associated both with gender (males exhibiting better knowledge of clinical signs and mode of transmission than females) and age group (participants aged 30-57 years having heard of HAT more frequently than people of other age groups). These findings suggest that the population of Bipindi exhibit knowledge and perceptions that can be useful for appropriation and sustainability of control interventions. Key words: Sleeping sickness, knowledge, perception, Bipindi, Cameroon.

Background The control of onchocerciasis currently relies on annual distribution of single dose ivermectin. Because ivermectin has minimal effects on the adult parasite, mass drug administration (MDA) campaigns against onchocerciasis require at least 15 years of annual uninterrupted ivermectin distribution. Mathematical models have predicted that short-term disruption of MDA (as was seen during COVID-19) could impacted the microfilaridermia prevalence depending on the pre-control endemicity and the histories of treatment, requiring corrective measures (such as biannual MDA) to mitigate the effect on onchocerciasis elimination. Field evidence supporting this prediction, however, has yet to be gathered. This study aimed to assess the impact of ~2 years disruption of MDA on onchocerciasis transmission indicators. Methodology A cross-sectional survey was carried out in 2021 in seven villages of Bafia and Ndikinimeki, two health districts located in the Centre Region, Cameroon, where MDA has been ongoing for two decades, but interrupted in 2020 as a response to the COVID-19 pandemic. Volunteers aged 5 years and above were enrolled for clinical and parasitological examinations for onchocerciasis. Data were compared with pre-COVID-19 prevalence and intensity of infection from the same communities to measure changes over time. Principal findings A total of 504 volunteers (50.3% males), aged 5–99 years (Median: 38; IQR: 15–54) was enrolled in the two health districts. The overall prevalence of microfilaridermia in 2021 was similar in Ndikinimeki health district (12.4%; 95% CI: 9.7–15.6) and Bafia health district (15.1%; 95% CI: 11.1–19.8) (p-value = 0.16). Microfilaridermia prevalences were either similar between 2018 and 2021 in the communities of Ndikinimeki health district (19.3% vs 12.8% (p = 0.057) for Kiboum 1; and 23.7% vs 21.4% (p = 0.814) for Kiboum 2), or higher in 2019 compared to 2021 in the communities of Bafia health district (33.3% vs 20.0% (p = 0.035) for Biatsota). The mean microfilarial densities in these communities dropped from 5.89 (95% CI: 4.77–7.28) mf/ss to 2.4 (95% CI: 1.68–3.45) mf/ss (p-value < 0.0001), and from 4.81 (95% CI: 2.77–8.31) mf/ss to 4.13 (95% CI: 2.49–6.86) mf/ss (p-value < 0.02) in Bafia and Ndikinimeki health districts, respectively. Community Microfilarial Load (CMFL) dropped from 1.08–1.33 mf/ss in 2019 to 0.052–0.288 mf/ss in 2021 in Bafia health district while remaining stable in the Ndikinimeki health district. Conclusion/Significance The continued decline in prevalence and CMFL observed ~2 years after MDA disruption is consistent with mathematical predictions (ONCHOSIM) and shows that additional efforts and resources are not needed to mitigate the effects of short-term MDA disruption in highly endemic settings prior to intervention with long treatment histories.

Entomological indicators of onchocerciasis transmission and the effect of climatic variables on the vector population dynamics were investigated in two first-line villages after more than two decades of mass drug administration with ivermectin. Female blackflies were collected in two villages (Bayomen and Biatsota) using human landing method for a period of 12 months. Blackflies were dissected and entomological indices were computed. Monthly temperature, precipitation, and humidity were collected and the Spearman correlation rank test was used to assess the relationship between biting rates and climatic variables. The highest biting rates (62,280 bites/human/month in Bayomen and 42,090 bites/human/month in Biatsota) were recorded during the long rainy season (November). The Onchocerca volvulus transmission was greater during the long dry season in both villages, with a peak at the beginning of the long dry season in Biatsota (100 infective larvae/human/month), and at the middle of the long dry season in Bayomen (92 infective larvae/human/month). No correlation was found between biting rates and selected climatic variables in the two villages. This study revealed that onchocerciasis transmission is ongoing in the study area despite almost 25 years of Community-Directed Treatment with Ivermectin. In accordance with WHO recommendations, vector control should be used in combination with mass drug administration to accelerate transmission interruption of onchocerciasis. To be optimal, this vector control should be implemented during the long dry season (November to March) when water volumes are low and transmission potentials are high.

BackgroundMany control methods have been implemented to tackle onchocerciasis and great successes have been achieved, leading to a paradigm shift from control of morbidity to interruption of transmission and ultimately elimination. The mandate of the African Programme for Onchocerciasis Control (APOC) ended in 2015, and endemic countries are to plan and conduct elimination activities by themselves, with technical assistance by the Expanded Special Project for Elimination of Neglected Tropical Diseases (ESPEN). To this end, an elimination expert committee was set up in Cameroon in 2018. This committee identified the need to update the data on the current situation of onchocerciasis. The present study aims to systematically review and report all available epidemiological data, including prevalence, intensity and transmission of onchocerciasis to provide pertinent information that will be useful to design optimal strategies to achieve onchocerciasis elimination in Cameroon.MethodsPubMed/MEDLINE, EMBASE and Web of Science will be searched from inception onwards. Grey literature will be identified through Google Scholar searches, dissertation databases and other relevant documents such as government reports. Eligible studies will be mostly observational, including cohort and cross-sectional surveys. No limitations will be imposed on publication status and study period. The primary outcomes will be (1) the prevalence and intensity ofOnchocerca volvulusinfection in humans, (2) transmission intensity and (3) impact of interventions on prevalence, intensity and transmission of onchocerciasis. Secondary outcomes will be environmental and socio-demographic factors supporting the primary outcomes. Two reviewers will independently screen all citations, full-text articles and abstract data. Potential conflicts will be resolved through discussion. Methodological quality including bias will be appraised using appropriate approaches. A narrative synthesis will describe quality and content of the epidemiological evidence. Prevalence and intensity of infection estimates will be stratified according to gender, age, geographical location and year of publication.DiscussionThis study will provide the health authorities as well as the scientific community with up-to-date information about the epidemiological situation of onchocerciasis in Cameroon. Understanding the spatiotemporal dynamics of the infection will help to define alternative and complementary strategies to accelerate onchocerciasis elimination in the country. Results of this review will also be used to update existing epidemiological models for onchocerciasis in order to fine-tune predictions of elimination timeframes in the country.Systematic review registrationThis protocol is under registration review in PROSPERO.

Background Points of Entry (POEs) are at the frontline for prevention, detection and response to international spread of diseases. The objective of this assessment was to ascertain the current level of existing International Health Regulations (IHR) core capacities of designated airports, ports and ground crossings in Cameroon and identify critical gaps for capacity building for prevention, early warning and response to public health threats including COVID-19. Methods Data were collected from April to May 2020 in 5 designated POEs: Yaounde Nsimalen International Airport (YIA), Douala international Airport (DIA), Douala Autonomous Port (DAP), Garoua-Boulai ground crossing, Kye-Ossi ground crossing which were all selected for their high volume of passenger and goods traffic. The World Health Organization (WHO) assessment tool for core capacity requirements at designated airports, ports and ground crossings was used to collect data on three technical capacities: (i) communication and coordination, (ii) Capacities at all times and (iii) capacities to respond to Public Health Emergencies of International Concern (PHEIC). Results All the investigated POEs scored below 50% of capacities in place. YIA recorded the highest percentage for all groups of capacities, coordination and communication and for core capacity at all times with a percentage of 42%, 58% and 32% respectively. For core capacity to respond to PHEIC, all the POEs recorded below 50%. The DAP and all ground crossings lacked trained personnel for inspection of conveyances. Only DIA had a public health emergency plan. There is no isolation/quarantine and transport capacity at the POEs. Conclusion All POEs assessed did not meet IHR standards and need significant improvement to fulfill the IHR requirements. Unstructured communication channels between stakeholders make the implementation of IHR challenging. A coordination mechanism, with clear functions and structure, is necessary for well-coordinated response efforts to health emergencies at POEs. This assessment will serve as a baseline to inform planning and IHR implementation at designated POEs in Cameroon.

Background The current mainstay for control/elimination of onchocerciasis and soil-transmitted helminthiasis (STH) relies on ivermectin- and mebendazole/albendazole-based preventive chemotherapies. However, children under five years of age have been excluded in both research activities and control programs, because they were believed to have insignificant infection rates. There is therefore a need for up-to-date knowledge on the prevalence and intensity of STH and onchocerciasis infections in this age group. This study aimed at assessing the rates and intensities of onchocerciasis and STH infections in children under five years of age who are excluded from ivermectin- or mebendazole/albendazole-based preventive chemotherapies. Methods A series of cross-sectional surveys was conducted in four Health Districts in the Centre and Littoral Regions of Cameroon between 2018 and 2019. All subjects aged 2 to 4 years, were screened for prevalence (or infection rate) and intensity [number of eggs per gram of stool (epg) or number of microfilariae per skin snip (mf/ss)] of STH and onchocerciasis infections respectively using the Kato-Katz and skin snip methodologies. Chi-square and the non-parametric tests (Mann Whitney and Kruskal Wallis) were used to compare infection rates and intensities of infections between Health Districts and genders, respectively. Results A total of 421 children were enrolled in this study. The overall prevalence of onchocerciasis was 6.6% [95% confidence interval (CI): 4.3‒9.9], ranging from 3.6% (in the Ntui Health District) to 12.2% (in the Bafia Health District). The intensity of infection ranged from 0.5 to 46 microfilariae per skin snip [median: 5; interquartile range (IQR): 2.25‒8.5]. The overall prevalence of STH was 9.6% (95% CI: 6.5‒13.9), with a high infection rate (29.6%) in the Akonolinga Health District. Two STH species (Ascaris lumbricoides and Trichuris trichiura) were found among infected individuals. The median intensities of STH infections were 1,992 epg (IQR: 210‒28,704) and 96 epg (IQR: 48‒168) for A. lumbricoides and T. trichiura, respectively. Conclusions This study reveals that children Graphical Abstract

The SD Bioline® IgG4 rapid diagnostic test (RDT) detects IgG4 antibodies induced by the Onchocerca volvulus-specific antigen Ov16. We evaluated the stability of the RDT results over 1 month, at different time points after completion of each assay, using eluted dried blood spots collected in central Cameroon. Agreement coefficients regarding positivity between 30 minutes and 24 hours, 1, 2, 3, and 4 weeks were, 96.4%, 93.4%, 93.3%, 93.2%, and 93.2%, respectively. Between 30 minutes and 24 hours, 3.6% of the 15,444 tests showed inconsistent results with 81.2% of these tests changing from negative to positive, increasing O. volvulus antibody prevalence from 23.9% to 26.2% (P < 0.0001). This change from negative to positive outcome was confirmed at the subsequent timepoints. Depending on the desired accuracy of prevalence estimates, reading time may have to be redefined more strictly.

Vector control using larvicides is the main alternative strategy to address limits of preventive chemotherapy using ivermectin for the control of onchocerciasis. However, it remains substantially limited by implementation difficulties, ecological concerns and the resistance of vector populations. Therefore, efficient and environmentally safe alternative control strategies are still needed. This study explores the composition of the blackfly bacteriome and its variability in the presence of Onchocerca volvulus infection, in order to determine their potential as a novel vector control-based approach to fight onchocerciasis. An entomological survey of a collection of samples was performed in the Bafia health district, a historical endemic focus for onchocerciasis in Cameroon. A total of 1270 blackflies were dissected and the infection rate was 10.1%, indicative of ongoing transmission of onchocerciasis in the surveyed communities. Sequencing process of blackflies’ gut DNA for bacteria screening revealed 14 phyla and 123 genera, highlighting the diversity of gut blackflies bacterial communities. Eight bacteria formed the core of blackfly bacteriome and Wolbachia was the predominant genus with 73.4% of relative abundance of blackflies’ gut bacterial communities. Acidomonas and Roseanomas genera were significantly abundant among infected blackflies (p = 0.01), whereas other genera such as Brevibacterium and Fructobacillus were associated with the absence of infection (p = 0.0009). Differences in gut bacterial distribution of blackflies according to their infection status by the parasite suggest a causal relationship between the bacteriome composition and the onset of blackflies’ infection by O. volvulus or vice versa. Blackfly native bacteria are then potentially involved in infection by O. volvulus, either by facilitating or preventing the parasite infestation of the vector. These bacteria represent an interesting potential as a biological tool/target for a novel approach of vector control to fight onchocerciasis.

Background The onchocerciasis focus surrounding the lower Mbam and Sanaga rivers, where Onchocerca volvulus is transmitted by Simulium damnosum s.l. (Diptera: Simuliidae), was historically the largest in the southern regions of Cameroon. Annual community-directed treatment with ivermectin (CDTI) has been taking place since 2000, but recent studies have shown that new infections are occurring in children. We aimed to investigate blackfly biting and O. volvulus transmission rates along the lower Mbam river 16 years after the formal onset of annual CDTI. Methods Black flies were collected for three consecutive days each month between July 2016 and June 2017 at two riverside villages and two inland sites situated 4.9 km and 7.9 km from the riverside. Specimens collected at each site were dissected on one of the three collection days each month to estimate parity rates and O. volvulus infection rates, while the remaining samples were preserved for pool screening. Results In total, 93,573 S. damnosum s.l. black flies were recorded biting humans and 9281 were dissected. Annual biting rates of up to 606,370 were estimated at the riverside, decreasing to 20,540 at 7.9 km, while, based on dissections, annual transmission potentials of up to 4488 were estimated at the riverside, decreasing to 102 and 0 at 4.9 km and 7.9 km, respectively. However, pool screening showed evidence of infection in black flies at the furthest distance from the river. Results of both methods demonstrated the percentage of infective flies to be relatively low (0.10–0.36%), but above the WHO threshold for interruption of transmission. In addition, a small number of larvae collected during the dry season revealed the presence of Simulium squamosum E. This is the first time S. squamosum E has been found east of Lake Volta in Ghana, but our material was chromosomally distinctive, and we call it S. squamosum E2. Conclusions Relatively low O. volvulus infection rates appear to be offset by extremely high densities of biting black flies which are sustaining transmission along the banks of the lower Mbam river. Graphical Abstract

The control of soil-transmitted helminthiasis (STH) in Cameroon is focused on large-scale deworming through annual mass drug administration (MDA) of albendazole or mebendazole to at-risk groups, principally pre-school and school-age children. After a decade of intervention, prevalence and intensity of infection have been significantly lowered, encouraging the paradigm shift from control to elimination. However, STH eggs are extremely resistant to environmental stressors and may survive for years in soils. It therefore appeared important to assess whether the risk of transmission was still prevailing, especially in a context where transmission of soil-transmitted helminths in the human population had almost been interrupted. A retrospective and a prospective cross-sectional surveys were conducted in five Health Areas of the Mifi Health District (West Region, Cameroon) to: (i) assess the trends in infestation rates over three-years (2018–2020) using health facility registers, and (ii) investigate, in 2020, the contamination rates of the environment by dissemination stages of soil-transmitted helminths using the sucrose centrifugal flotation method. The overall soil-transmitted helminth infestation rate was 4.9% (95% CI: 4.3–5.6), significantly lower than the overall soil contamination rate (12.0%, 95% CI: 8.2–17.2). These results are supportive of the low endemicity level of STHs in the Mifi Health District, but environmental pollution by dissemination stages of the parasites outlines that the risk of transmission is still persistent. It therefore appears compulsory to account for the environment when considering policy/recommendations for transmission interruption and stopping MDA, as it is in the case with vector-borne diseases.

Background Loiasis is a vector-borne parasitic disease due to Loa loa and transmitted to humans by tabanids of the genus Chrysops. Loiasis has been historically considered as the second or third most common reason for medical consultation after malaria, and a recent study has reported an excess mortality associated with the infection. However, the clinical impact of this filarial disease is yet to be elucidated, and it is still considered a benign disease eliciting very little attention. As a consequence of post-treatment severe adverse events occurring in individuals harboring very high Loa microfilarial loads, ivermectin is not recommended in onchocerciasis hypo-endemic areas that are co-endemic for loiasis. Without treatment, it is likely that the transmission of the disease and the morbidity associated with the infection will increase over time. This study aimed at investigating the long-term trends in prevalence and intensity of Loa loa infection in an area where no mass anti-filarial treatment has ever been distributed. Methods A cross-sectional survey was conducted in three communities of the Mbalmayo health district (Central Cameroon). All volunteers, males and females aged five years and above, underwent daytime calibrated thick blood smears (CTBS) to search for L. loa microfilariae (mf). A structured questionnaire was administered to assess the history of both loiasis related clinical signs and migration of enrollees. Results The prevalence of loiasis was 27.3% (95% CI: 22.3–32.9) in the three surveyed communities, with a mean mf density of 1922.7 (sd: 6623.2) mf/mL. Loa loa infection rate was higher amongst females than in males (p = 0.0001) and was positively associated with age of (OR = 1.018; p = 0.007). The intensity of infection was higher among males than in females (p

Background and objectives Preventive chemotherapy (PCT) is the main strategy currently used to control and/or eliminate onchocerciasis, lymphatic filariasis (LF) and soil transmitted helminthiasis (STH), and community participation (through implementation or adherence to PCT) is critical. This study aimed at investigating knowledge/perceptions of populations of the Mbengwi health district (North West Region, Cameroon), in relation to their attitudes/practices regarding the most prevalent neglected tropical diseases (NTDs). Methods A household-based cross-sectional survey was carried out in the Mbengwi health district (North West Region, Cameroon) using the cluster sampling technique. Clusters were selected using the probability proportionate to estimate size strategy. In each cluster, the random walk technique was used for the selection of households, and a structure questionnaire was administered to 2–3 of its members. Results A total of 254 households from 26 clusters were visited, and 514 individuals were interviewed. The sex ratio of interviewees (1.08) was unbiased, and their ages ranged between 10 and 99 years old. Though most of the respondents declared having already heard of these NTDs (41.6%, 73.9% and 90.5% for onchocerciasis, LF and STH, respectively), only a minority of them were aware of how they are acquired/transmitted (8.9%, 9.2% and 32.7% for onchocerciasis, LF and STH, respectively), or prevented (23.1%, 18.9% and 47.2% for onchocerciasis, LF and STH, respectively). Conclusions This study revealed poor knowledge/perceptions and wrong attitudes/practices of interviewees as regards to these NTDs, and these misconceptions can seriously affect the adherence and contribution of populations to the success of PCTs. It appears compulsory to reinforce information, education, and communication, with a focus on the rationale and importance behind PCTs, to optimize/improve community participation.

Background: Infection with resistant Pseudomonas aeruginosa (RPA) in Intensive Care Unit (ICU) is known to be either endogenous or exogenous or both, but the roles of each of these contamination routes is yet to be clarified. Data regarding prevalence, risk factors and environmental factors associated with RPA in ICU are very scanty and even when they exist, they seem to be contradictory. So, there is a strong interest in understanding both individual and environmental factors associated with RPA infection. This systematic review aims to investigate individual and environmental factors associated with the colonization and infection with RPA in ICU.Methodology: MEDLINE (Pubmed), EMBASE (OVID), the Cochrane Library (Wiley), Web of Science, CINAHL (EBSCOHost) and LILACS (BIREME) will be searched from inception onwards. Grey literature will be identified through Google Scholar and open Grey. Two reviewers will independently screen all citations, abstracts and full-text articles. Potential conflicts will be resolved through discussion. Methodological quality including bias will be appraised using appropriate approaches. A narrative synthesis will describe quality and content of the epidemiological evidence. Prevalence, Odds ratio, Relative Risk, Hazard radio with their respective 95% confidence intervals will be calculated. A meta-analysis of data extracted from eligible studies with similar population and RPA testing will be performed. The analysis will evaluate factors influencing the estimates. A random effect model will be used to summarize effect sizes.Discussion: Two contrasting hypotheses on risk factors of acquisition, colonisation, and infection of RPA are being debated, especially in a context where available data are scanty or exhibit high discrepancy. Indeed, most of the reviews have been focalized on hospitalised patients, and not in ICU, and few of them really address the environmental factors issue. To fill that gap, this review will combine both analysis of individual and environmental risk factors using prevalence study in ICU and evaluation of different methodologies. These two hypotheses will be tested and challenged, and could serve as a basis for a more in-depth studies to fill the methodological gaps that will be identified as part of this current review.Systematic review registration: This protocol has been submitted registered with Prospective Register of Systematic Reviews (PROSPERO) on 07 march 2021 under number CRD42021233832

The standard techniques for diagnosis of human filariasis are the microscopic examination of blood smears or skin biopsies, which are relatively invasive and poorly sensitive at low levels of infection. Recently, filarial DNA has been detected in fecal samples from non-human primates in Central Africa. The aim of this study was to demonstrate proof-of-concept of a non-invasive molecular diagnosis technique for human filariasis by targeting fragments of 12S rDNA, Cox1, ITS1 and LL20-15kDa ladder antigen-gene by conventional PCR in DNA extracted from stool samples of 52 people infected with Mansonella perstans and/or Loa loa . Of these, 10 patients were infected with soil-transmitted helminths ( Trichuris trichiura and/or Ascaris lumbricoides ), and none were positive for Necator americanus . Interestingly, no filarial gene fragments were detected in the stools of any of the 52 patients. Future studies should evaluate whether a co-infection with soil-transmitted helminths causing gastrointestinal bleeding and likely allowing (micro)filaria exit into the digestive tract, may facilitate the molecular detection of filarial DNA fragments in stool samples., Les techniques standards de diagnostic des filarioses humaines (examen microscopique de gouttes épaisses ou de biopsies cutanées) sont relativement invasives et peu sensibles à de faibles niveaux d’infection. De l’ADN de filaires a été récemment détecté dans des échantillons de fèces de primates non-humains en Afrique centrale. L’objectif de cette étude était de démontrer la preuve de concept d’un diagnostic moléculaire non invasif des filarioses chez l’homme en ciblant des fragments d’ADNr 12S, Cox1, ITS1 et l’antigène LL20-15kDa par PCR classique. L’ADN a été extrait d’échantillons de selles de 52 personnes infectées par Mansonella perstans et/ou Loa loa . Parmi ces patients, dix étaient infectés par des géohelminthes ( Trichuris trichiura et/ou Ascaris lumbricoides ) et aucun n’était positif pour Necator americanus . De manière intéressante, aucun fragment de gène de filaires n’a été détecté dans les selles des 52 patients. Des études futures devraient être menées pour évaluer si une coinfection avec des géohelminthes (provoquant des hémorragies gastro-intestinales et permettant probablement l’effraction de (micro)filaires dans le tube digestif) facilite la détection moléculaire de fragments d’ADN de filaires dans les selles.

Background Onchocerciasis elimination currently relies on repeated ivermectin-based preventive chemotherapy. Current World Health Organization’s guidelines strongly recommend, though with low evidence of certainty, the use of Ov16 serology testing in children younger than 10 years old to assess whether mass drugs administration can be safely stopped. Therefore, more evidences are needed to support the use of this marker as sero-evaluation tool. This study aimed at determining the relationship between microfilaridermia and anti-Ov16 IgG4, and their variation according to age, gender and ivermectin intake history. Methodology A cross-sectional survey was conducted in an area where ivermectin-based MDA has been implemented since more than 20 years. A questionnaire was used to record ivermectin intake history for the last 5 years. All volunteers aged ≥2 years were tested for microfilaridermia. IgG4 antibodies against Ov16 antigen were determined using the Standard Diagnostic Ov16 IgG4 ELISA kits and the recombinant anti-Ov16 AbD19432 antibodies. Prevalences, microfilaridermia counts and IgG4 concentrations were compared with regards to age, gender and history of ivermectin intake. Principal findings The prevalence of skin microfilariae was 23.4% (95% CI: 23.4–30.8), whereas Ov16 seroprevalence was 53.2% (95% CI: 47.9–58.4). A moderate positive percentage agreement (50.4%) and a high negative percentage agreement (69.2%) was found between skin snip and Ov16 serology in the whole population, while in children aged Conclusion/Significance Our results revealed moderate positive and negative agreements between parasitological and immunological parameters of onchocerciasis infection after several rounds MDA. Anti-Ov16 IgG4 levels increased with age but decreased with microfilarial counts, suggesting a variation of anti-Ov16 IgG4 as a result of constant exposure and accumulation of infection. This brings evidence sustaining the use of Ov16 serology in children as evaluation tool. However, additional investigations are needed to further reshape the appropriate age range among children aged

Ivermectin (IVM) is a broad spectrum endectocide whose initial indication was onchocerciasis. Although loiasis is not among its indications, IVM also exhibits antiparasitic activity against Loa loa. IVM-based preventive chemotherapies (PCs), so-called community-directed treatment with ivermectin (CDTI), have led to the interruption of transmission of onchocerciasis in some foci. A cross-sectional study was conducted in the Yabassi Health District where CDTI have been implemented since 20 years to fight onchocerciasis. All volunteers aged &ge, 5 years underwent daytime calibrated thick blood smears to search for L. loa microfilariae (mf). The prevalence of loiasis was 3.7% (95% CI: 2.2&ndash, 6.2), significantly lower than its baseline prevalence (12.4%, 95% CI: 10.1&ndash, 15.2, Chi-Square = 21.4, df = 1, p &lt, 0.0001). Similarly, the microfilarial density was significantly low (mean = 1.8 mf/mL, SD = 13.6, max = 73,600) compared to baseline microfilarial density (mean = 839.3 mf/mL, SD = 6447.1, max = 130,840, Wilcoxon W = 179,904.5, 0.0001). This study revealed that the endemicity level of loiasis was significantly low compared to its baseline value, indicating a significant impact of IVM-based PC on this filarial disease. However, transmission is still ongoing, and heavily infected individuals are still found in communities, supporting why some individuals are still experiencing severe adverse events despite &gt, 2 decades of CDTI in this Health District.

Background Soil-transmitted helminth (STH) infections remain a public health concern in sub-Saharan Africa. School-based mass drug administration (MDA) using the anthelminthic drug Mebendazole/Albendazole have succeeded in controlling morbidity associated to these diseases but failed to interrupt their transmission. In areas were filarial diseases are co-endemic, another anthelminthic drug (Ivermectin) is distributed to almost the entire population, following the community-directed treatment with ivermectin (CDTI) strategy. Since Ivermectin is a broad spectrum anthelmintic known to be effective against STH, we conducted cross-sectional surveys in two health districts with very contrasting histories of Ivermectin/Albendazole-based PC in order to investigate whether CDTI might have contributed in STH transmission interruption. Methodology Cross-sectional surveys were conducted in two health districts with similar socio-environmental patterns but with very contrasting CDTI histories (Akonolinga health district where CDTI was yet to be implemented vs. Yabassi health district where CDTI has been ongoing for two decades). Stool samples were collected from all volunteers aged >2 years old and analyzed using the Kato-Katz technique. Infections by different STH species were compared between Akonolinga and Yabassi health districts to decipher the impact of Ivermectin/Albendazole-based MDA on STH transmission. Principal findings A total of 610 and 584 participants aged 2–90 years old were enrolled in Akonolinga and Yabassi health districts, respectively. Two STH species (Ascaris lumbricoides and Trichuris trichiura) were found, with prevalence significantly higher in Akonolinga health district (43.3%; 95% CI: 38.1–46.6) compared to Yabassi health district (2.5%; 95% CI: 1.1–5.1) (chi-square: 90.8; df: 1; p < 0.001). Conclusion/significance These findings (i) suggest that Mebendazole- or Albendazole-based MDA alone distributed only to at-risk populations might not be enough to eliminate STH, (ii) support the collateral impact of Ivermectin/Albendazole MDA on A. lumbricoides and T. trichiura infections, and (iii) suggest that Ivermectin/Albendazole-based PC could accelerate STH transmission interruption., Author summary Decades of preventive chemotherapy (PC) using Mebendazole/Albendazole among school-aged children had not significantly decreased STH prevalence and intensity of infection, and Mathematical modelling demonstrated that interruption in STH transmission cannot be achieved unless MDA are broadened to an important proportion of the entire population. Concurrently, Ivermectin has been considered as a wonder drug because of (i) its applications in veterinary medicine, (ii) its tremendous impact on its initial indication in human medicine (river blindness), and (iii) its large spectrum of activity up to quite unsuspected effects on Human Immunodeficiency Virus (HIV). The efficacy of Ivermectin on STH has therefore been largely documented since the 2000s. Since Ivermectin/Albendazole-based MDA is administered to almost the entire population, we conducted cross-sectional surveys in two health districts with very contrasting histories of Ivermectin/Albendazole mass distributions to investigate whether Ivermectin/Albendazole-based PC might have interrupted STH transmission. Our findings confirm that Mebendazole- or Albendazole-based MDA alone and administered only to at-risk groups is not enough to eliminate STH and suggest that PC with Ivermectin (in combination to Albendazole) administered almost to the entire population would have contributed to STH transmission interruption. These observations are supportive of revision of WHO guidelines and recommendations to fight against STH.

Background Ivermectin (IVM) is a broad spectrum endectocide whose initial indication was onchocerciasis. IVM-based preventive chemotherapies (PC), so-called Community-Directed Treatment with Ivermectin (CDTI), have led to the interruption of transmission of onchocerciasis in some foci. Although loiasis is not among its indications, IVM also exhibits antiparasitic activity against Loa loa. Because of the geographic overlap of onchocerciasis and loiasis in Central Africa, one would have expected similar trend for loiasis in co-endemic settings. Surprisingly, a recent study revealed that L. loa entomological indices remained almost unchanged after 13 years of CDTI to fight onchocerciasis. This study then aimed to assess whether parasitological indicators of L. loa infection follow the same trends than the previously described entomological indices. A cross-sectional study was conducted in six communities of the Yabassi Health District where CDTI have been implemented since ~ 20 years to fight onchocerciasis. All volunteers aged ≥ 5 years underwent daytime calibrated thick blood smears to search for L. loa microfilariae (mf), then prevalence and intensity of infection were compared to baseline data. Results A total of 376 individuals (55.9% female), aged 5 to 89 years old, were enrolled in this study. The prevalence of loiasis was 3.7% (95% CI: 2.2–6.2), significantly lower than its baseline (12.4%; 95% CI: 10.1–15.2) (Chi-Square = 21.4; df = 1; p p L. loa infection were significantly low compared to their baselines, indicating a significant impact of IVM-based PC on this filarial disease. However, transmission is still ongoing, and heavily infected individuals are still found in communities, supporting why some individuals are still experiencing severe adverse events despite > 2 decades of CDTI in this Health District.

Background Ivermectin-based preventive chemotherapy (PC) is distributed annually to all at-risk populations eligible for ivermectin treatment to control and/or eliminate onchocerciasis. Information on the impact of mass ivermectin administration on onchocerciasis transmission is scanty, and it is tricky to appreciate the progress towards elimination and engage corrective measures. To fill that gap in the Centre Region in Cameroon, the current onchocerciasis endemicity level in the Ndikinimeki Health District after about two decades of mass treatments was assessed. Methods A cluster-based cross-sectional survey was carried out in the Ndikinimeki Health District and all volunteers aged ≥ 5 years were (i) interviewed on their compliance to ivermectin over the past five years and (ii) underwent clinical (nodule palpation and visual search for onchocercal lesions) and parasitological examinations (skin snip) for onchocerciasis. Results The overall Onchocerca volvulus prevalence was 7.0% (95% CI: 5.2–9.3%). The prevalence of the disease was significantly higher in the communities Kiboum 1 and Kiboum 2 compared to the other communities (highest prevalence in Makénéné Town Water: 8.5%; 95% CI: 2.3–20.4%) (χ2 = 51.314, df = 11, P = 0.0001). The proportion of systematic non-compliers to ivermectin was 23.3% (95% CI: 19.9–27.1%) among individuals interviewed. In the sentinel sites (Kiboum communities), onchocerciasis prevalence decreased from 95.2% (95% CI: 88.3–98.1%) to 23.7% (95% CI: 14.7–36.0%). Conclusions This study has revealed that the Ndikinimeki Health District is hypo-endemic for onchocerciasis after about two decades of preventive chemotherapy. However, transmission is ongoing, with potential hotspots in the Kiboum 1 and Kiboum 2 communities, which are known as first-line communities (closest to the breeding sites of the vector). Alternative or complementary strategies to annual ivermectin appear compulsory to accelerate the momentum towards onchocerciasis elimination.

Summary Background A test-and-not-treat (TaNT) strategy has been developed to prevent people with high concentrations of circulating Loa loa microfilariae (>20 000 microfilariae per mL) developing serious adverse events after ivermectin treatment during mass drug administration to eliminate onchocerciasis. An important question related to cost and programmatic issues is whether annual retesting is required for everyone. We therefore aimed to investigate changes in L loa microfilarial densities during TaNT campaigns run 18 months apart. Methods In this observational cohort study, we assessed the participants of two TaNT campaigns for onchocerciasis. These campaigns, which were run by a research team, together with personnel from the Ministry of Health and community health workers, were done in six health areas (in 89 communities) in Okola health district (Cameroon); the first campaign was run between Aug 10, and Oct 29, 2015, and the second was run between March 7, and May 26, 2017. All individuals aged 5 years and older were invited to be screened for Loa loa microfilaraemia before being offered ivermectin (unless contraindicated). L loa microfilarial density was measured at the point of care using the LoaScope. All those with a L loa microfilarial density of 20 000 microfilariae per mL or less were offered treatment; in the first 2 weeks of the 2015 campaign, a higher exclusion threshold of 26 000 microfilariae per mL or less was used. At both rounds of the intervention, participants were registered with a paper form, in which personal information were collected. In 2017, we also recorded whether each individual reported participation in the 2015 campaign. The primary outcome, assessed in all participants, was whether L loa microfilarial density was above or below the exclusion threshold (ie, the criteria that guided the decision to treat). Findings In the 2015 TaNT campaign, 26 415 people were censused versus 29 587 people in the 2017 TaNT campaign. All individuals aged 5 years and older without other contraindications to treatment (22 842 people in 2015 and 25 421 people in 2017) were invited to be screened for L loa microfilaraemia before being offered ivermectin. In 2015, 16 182 individuals were examined with the LoaScope, versus 18 697 individuals in the same communities in 2017. 344 (2·1%) individuals were excluded from ivermectin treatment because of a high L loa microfilarial density in 2015, versus 283 (1·5%) individuals in 2017 (p99·9%) of 6983 individuals treated with ivermectin in 2015 had L loa microfilariae density below the level associated with neurological serious adverse events. Interpretation Individuals treated with ivermectin do not need to be retested for L loa microfilaraemia before the next treatment, provided that they can be re-identified. This adjusted approach will enable substantial cost savings and facilitate reaching programmatic goals for elimination of onchocerciasis in areas that are co-endemic for loiasis. Funding Bill & Melinda Gates Foundation, Division of Intramural Research (National Institute of Allergy and Infectious Diseases, US National Institutes of Health).

Community-Directed Treatment with Ivermectin (CDTI) is the strategy of choice to fight onchocerciasis in Africa. In areas where loiasis is endemic, onchocerciasis control and/or elimination is hindered by severe adverse events (SAEs) occurring after ivermectin mass treatments. This study aimed at (i) investigating the impact of two decades of CDTI on L. loa clinical and parasitological indicators in the Ndikinimeki Health District, and (ii) assessing the risk of SAEs after this long-term preventive chemotherapy. A cluster-based cross-sectional survey was conducted in the six Health Areas of the Ndikinimeki Health District. All volunteers underwent day-time calibrated thick blood smears to search for L. loa microfilariae, as well as an interview to assess the history of migration of eye worm and Calabar swelling. The overall prevalence of L. loa microfilaraemia was 2.2 % (95% CI: 1.3-3.7%), and the proportions of individuals who had already experienced eye worm and/or Calabar swelling were 1.0% and 0.5%, respectively. The mean microfilarial density was 63.55 (SD: 559.17; maximum: 9220.0) mf/mL. These findings indicate that (i) the long-term ivermectin-based preventive chemotherapy against onchocerciasis significantly reduced L. loa clinical and parasitological indicators, and (ii) the risk of developing neurologic and potentially fatal SAE after ivermectin mass treatment is zero in the Ndikinimeki Health District.

Malaria interventions - vector control using long-lasting insecticidal nets (LLINs) or indoor residual spraying, chemoprevention and case management including diagnosis and treatment of infections - are highly effective and affordable. These interventions have led to a significant reduction in malaria prevalence, and a marked decline in morbidity and mortality associated. Despite these increasing control efforts, this parasitic disease is still persisting in most African countries. The aim of this study was to investigate the risk factors associated with malaria infection in the Obang Valley (North Western Cameroon) in order to identify potential bottlenecks in the malaria elimination procedure. A structured questionnaire was administered to a random sample of 100 individuals visiting the Mbakong Health Centre or attending the Obang Government High School. Association between malaria infection and individual household or environmental risk factors was investigated using logistic regression models. Malaria infection was not significantly associated with LLIN possession (p = 0.999) since 97% of interviewees received them free of charge. The age and habits (having each bed cover by a LLIN, time when doors and windows are closed or antimalarial medicine used) of study participants were however significantly associated with malaria infection (p < 0.033). These findings suggest that although the interventions recommended by the World Health Organization may help in reducing malaria prevalence and burden, it is of prime importance to also tackle associated risk factors which are mostly related to individual habits. Key words: Malaria, risk factors, Obang Valley, Cameroon.

Background Surveys conducted in 1991–1992 in the Mbam Valley (Cameroon) revealed that onchocerciasis was highly endemic, with community microfilarial loads (CMFL) > 100 microfilariae/snip in some villages. Also in 1991–1992, a survey of suspected cases of epilepsy (SCE) found 746 SCE using a questionnaire administered to individuals identified by key informants, with prevalences reaching 13.6% in some communities. From 1998, annual community-directed treatment with ivermectin (CDTI) was implemented to control onchocerciasis. In 2017, a door-to-door household survey was conducted in three of the villages visited in 1991–1992, using a standardized 5-item epilepsy screening questionnaire. Results In 2017, a total of 2286 individuals living in 324 households were screened (582 in Bayomen, 553 in Ngongol and 1151 in Nyamongo) and 112 SCE were identified (4.9%). Neurologists examined 92 of these SCE and confirmed the diagnosis of epilepsy for 81 of them (3.5%). Between the surveys in 1991–1992 and 2017, the prevalence of SCE decreased from 13.6% to 2.5% in Bayomen (P = 0.001), from 8.7% to 6.6% in Ngongol (P = 0.205) and from 6.4% to 5.4% in Nyamongo (P = 0.282). The median age of SCE shifted from 20 (IQR: 12–23) to 29 years (IQR: 18–33; P = 0.018) in Bayomen, from 16 (IQR: 12–21) to 26 years (IQR: 21–39; P

Loiasis is a vector-borne parasitic disease caused by the filarial nematode Loa loa and transmitted by the tabanid vectors from the genus Chrysops. Loa loa infection is associated with clinical manifestations such as pruritus, migratory transient edema, passage of adult worm in the bulbar conjunctiva, retinal damage, glomerular damage, albuminuria, pleural effusion, hydrocele, and endomyocardial fibrosis. Data reporting the occurrence of spontaneous encephalopathy associated with loiasis are very scanty. Severe adverse events occurring post-ivermectin administered in the framework of the fight against onchocerciasis and/or lymphatic filariasis in loiasis co-endemic areas have been closely associated with very high L. loa microfilariaemia. Different regimens have been used to lower L. loa microfilariaemia before definitive treatment, and many discrepancies have been reported. We report the case of a patient who was admitted to a health facility and hospitalized for 34 days for altered consciousness, blurred vision, headache, and chills. After other potential diagnoses were eliminated, the patient was confirmed with encephalopathy due to loiasis and referred to the Centre for Research on Filariasis and other Tropical Diseases (CRFilMT). On admission at CRFilMT, the patient was harboring 28,700 microfilariae per milliliter of blood (mf/mL), and after four 21-day courses of 400 mg daily albendazole, the L. loa microfilariaemia lowered to 5,060 mf/mL. The patient was then treated with ivermectin 3 mg and a total clearance of microfilariae was observed, with satisfactory clinical evolution and no adverse event. This case study further confirmed that albendazole is effective against L. loa, but might necessitate a longer course.

Introduction: Blastocystis spp. is a protist found in humans. Although usually the most frequent protozoa found in stool samples of both symptomatic and healthy subjects, its pathogenic or rather opportunistic role is yet to be clearly elucidated. To attempt to fill this gap, a cross-sectional study was conducted to compare the frequency of Blastocystis spp. in HIV positive (HIV+) versus HIV negative (HIV-) individuals in four health facilities of the Center Region of Cameroon. Methodology: Stool samples were collected from 283 HIV positive and 245 HIV negative subjects and analyzed using direct diagnostic tests. Results: A total of 46 (8.7%) individuals were found infected with Blastocystis spp., including 6.7% HIV positive and 11.0% HIV negative. This species was more frequent in urban and semi-urban areas than in rural areas, but evenly distributed among genders and age groups as well as among all sectors of activity. The prevalence of Blastocystis spp. (11.3%) was higher in HIV+ patients with a CD4 count ≥ 500 cells / mm3, but no significant difference was found among HIV clinical stages. Likewise prevalence, the mean number of cysts per gram of stool was similar between HIV positive and HIV negative individuals. People infected with Blastocystis spp. showed diverse clinical signs, but only flatulence was significantly more prevalent. The frequencies of these clinical signs were not related to HIV status. Conclusion: No clear relationship links the infection with Blastocystis spp. to HIV, although its presence was associated with digestive disorder, suggesting that this parasite might not be opportunist.