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Background: Neglected Tropical Diseases amenable to Preventive Chemotherapy (PC-NTDs) affect the poorest populations around the world, especially in Africa. Scientific information on the distribution and level of endemicity of these diseases in the Republic of the Congo (RoC) is scarce in the published literature. We sought to collect all available epidemiological data on PC-NTDs in the RoC to document the historical and current situation and identify challenges in reaching the elimination of NTDs., Methods: We searched Medline and Horizon databases for studies published until to July 4th, 2019, on onchocerciasis, lymphatic filariasis, soil-transmitted helminth infections, schistosomiasis, and trachoma in the RoC. Unpublished reports were also reviewed. We included all epidemiological studies containing community data and excluded case reports. Location, prevalence data, and dates of the studies were extracted., Principal Findings: We identified 933 records, of which 56 met the inclusion criteria. The articles published before 1960 mainly concerned onchocerciasis and schistosomiasis. Despite a low number over the studied period, since 2005 there has been a steady increase in the number of publications. Most of the studies were cross-sectional and conducted in the general population. Trachoma is endemic in the Sangha and Likouala departments (prevalence of trachomatous inflammation-follicular > 5% in some villages), and further mapping is essential to properly assess the burden of this disease in the country. While the prevalence of soil-transmitted helminths is still high (over 20%) in a large part of Congo, cases of lymphatic filariasis (based on Wuchereria bancrofti antigenaemia and/or microfilaraemia) and onchocerciasis are becoming rare and very focused. To achieve the elimination of PC-NTDs, further intervention is required., Conclusions: Except for trachoma, whose epidemiological situation should be better evaluated, PC-NTDs are endemic in the RoC, and actions to control them have been taken by health authorities. To eliminate PC-NTDs, which are still present in some locations, new mapping surveys are needed, and increased investment in scientific research should be encouraged in the country., Competing Interests: The authors claim to have no conflict of interest.

Little is known about the effect of helminth infections on the natural gynecological and pregnancy course. Our goal was to assess the relationship between Wuchereria bancrofti and hookworm (HW) infections with pregnancy course and outcome in a group of 82 women living in a rural area of the Democratic Republic of the Congo. Demographics and information on gynecological and obstetrical histories were collected retrospectively with standardized questionnaires. Wuchereria bancrofti and HW infections were diagnosed using a filarial antigen-detection test and the Kato-Katz method, respectively. Analyses consisted of multivariable logistic regressions adjusting for age, number of deliveries, and history of anthelmintic treatment (HAHT). The median age of study participants was 35 (interquartile range [IQR]: 30-44) years, and the median number of deliveries was five (IQR: 3-7). Wuchereria bancrofti and HW infection rates were 44.5% and 43.3%, respectively. Filarial antigenemia and HW infection were not significantly associated with the number of deliveries. The proportions of women with a history of pregnancy resulting in neonatal death, miscarriage, premature birth, and postpartum hemorrhage were 56%, 44%, 23%, and 36%, respectively. History of pregnancy associated with neonatal death was less frequent in women with HAHT, tended to be more frequent in women with filarial antigenemia, and was not associated with HW infection. None of the three other pregnancy events studied (miscarriage, premature birth, and postpartum hemorrhage) were associated with filarial antigenemia or HW infection. The positive association found between HAHT and lower risk of neonatal death warrants investigation in larger groups of women.

Background: Little is known regarding risk factors for lymphatic filariasis (LF) in Central Africa. To expand on what is known, we studied the epidemiology of LF in two endemic villages in the Democratic Republic of the Congo., Methods: Dependent variables were Wuchereria bancrofti antigenaemia detected with filarial test strips (FTS) and microfilaraemia detected by night blood smears. The following factors were investigated: sex, age, the use of bednets, the use of latrines, hunting, fishing and agricultural activities, history of treatment with anthelmintic drugs, overnight stays in the bush, population density, the number of household members, and distance to rivers. Mixed multivariate logistic regression models were used., Results: Two hundred and fifty nine out of 820 (31.6%) of subjects aged ≥ 5 years had W. bancrofti antigenaemia and 11.8% (97/820) had microfilaraemia. Multivariable analysis of risk factors for antigenaemia demonstrated increased risk for males (aOR = 1.75, 95% CI: 1.20-2.53, P = 0.003), for older individuals (aOR = 9.12 in those aged > 35 years, 95% CI: 4.47-18.61, P < 0.001), for people not using bednets (aOR = 1.57, 95% CI: 1.06-2.33, P = 0.023), for farmers (aOR = 2.21, 95% CI: 1.25-3.90, P = 0.006), and for those who live close to a river (aOR = 2.78, 95% CI: 1.14-6.74, P = 0.024). Significant risk factors for microfilaraemia included age, male gender, overnight stay in the bush, and residence close to a river (aOR = 1.86, 2.01, 2.73; P = 0.011, 0.010, 0.041; for the three latter variables, respectively). People who reported having taken levamisole (n = 117) during the prior year had a significantly decreased risk of having filarial antigenaemia (aOR = 0.40, 95% CI: 0.21-0.76, P = 0.005)., Conclusions: Age, sex, not using bednets, and occupation-dependent exposure to mosquitoes were important risk factors for infection with W. bancrofti in this study. The association with levamisole use suggests that the drug may have prevented filarial infections. Other results suggest that transmission often occurs outside of the village. This study provides interesting clues regarding the epidemiology of LF in Central Africa.

After 30 years of treatment with Mectizan (ivermectin), cutaneous and ocular complications of Onchocerca volvulus infection are now scarce in endemic communities. Indeed, transmission has been interrupted and the O. volvulus- associated disease has disappeared in some African foci. Despite this success, onchocerciasis elimination in Loa loa co-endemic areas is still constrained by severe adverse events (SAEs) occurring after ivermectin treatment in some individuals harbouring very high L. loa microfilaremia. One approach towards the prevention of these SAEs is to identify individuals with high L. loa microfilaremia and exclude them from ivermectin treatment. The development of the LoaScope has provided the tool that underlies this test and not treat (TaNT) strategy. The first successful TaNT campaign was conducted in a L. loa highly endemic focus in Cameroon in 2015 without any SAEs. To accomplish this within a research setting, 60 people were deployed for this campaign, making this 'research' strategy not sustainable from a cost perspective. We describe here a way of reducing the cost of the TaNT strategy with a smaller team (three people) selected within affected communities. We also suggest the organization of a TaNT campaign in affected countries.

Background: The Global Programme to Eliminate Lymphatic Filariasis uses point-of-care tests for circulating filarial antigenemia (CFA) to map endemic areas and for monitoring and evaluating the success of mass drug administration (MDA) programs. We compared the performance of the reference BinaxNOW Filariasis card test (ICT, introduced in 1997) with the Alere Filariasis Test Strip (FTS, introduced in 2013) in 5 endemic study sites in Africa., Methodology: The tests were compared prior to MDA in two study sites (Congo and Côte d'Ivoire) and in three sites that had received MDA (DRC and 2 sites in Liberia). Data were analyzed with regard to % positivity, % agreement, and heterogeneity. Models evaluated potential effects of age, gender, and blood microfilaria (Mf) counts in individuals and effects of endemicity and history of MDA at the village level as potential factors linked to higher sensitivity of the FTS. Lastly, we assessed relationships between CFA scores and Mf in pre- and post-MDA settings., Principal Findings: Paired test results were available for 3,682 individuals. Antigenemia rates were 8% and 22% higher by FTS than by ICT in pre-MDA and in post-MDA sites, respectively. FTS/ICT ratios were higher in areas with low infection rates. The probability of having microfilaremia was much higher in persons with CFA scores >1 in untreated areas. However, this was not true in post-MDA settings., Conclusions/significance: This study has provided extensive new information on the performance of the FTS compared to ICT in Africa and it has confirmed the increased sensitivity of FTS reported in prior studies. Variability in FTS/ICT was related in part to endemicity level, history of MDA, and perhaps to the medications used for MDA. These results suggest that FTS should be superior to ICT for mapping, for transmission assessment surveys, and for post-MDA surveillance.

Since the mid-2000s, the immunochromatographic card test (ICT), a point-of-care test for detecting Wuchereria bancrofti circulating filarial antigens (CFAs), has been the backbone for mapping and monitoring lymphatic filariasis (LF) worldwide. Recently, there have been instances in which CFA positivity has been associated with Loa loa microfilaremia. Here, we examined the association, at both the community and individual levels, between L. loa and CFA using additional diagnostic tools (quantitative polymerase chain reaction [qPCR], Og4C3 enzyme-linked immunosorbent assay, and IgG4 antibodies to Wb123 assays) to demonstrate the relationship between L. loa microfilaremia and ICT positivity. In May 2013, peripheral blood was collected during the day from 1,812 individuals living in southern Cameroon. ICT tests were done on the spot, and positive individuals were resampled at night. Results of qPCR and Wb123 assays concurred proving the absence of W. bancrofti infection. Og4C3 assays indicate a quantitative relationship between the level of L. loa microfilaremia and that of CFA. This was confirmed by epidemiological analyses, which reveal a strong association between L. loa microfilaremia and ICT positivity, with 50% of ICT reacting to L. loa when its microfilarial density exceeds 30,000 microfilariae/mL. At the community level, the proportion of positive ICT would exceed 2% when the prevalence of L. loa microfilaremia in the total population is above 20%. This has significant implications in terms of mapping and control of LF caused by W. bancrofti in Loa-endemic areas. Cross-reactivity of ICT with L. loa has to be considered in the context of both individual and community diagnostics., (© The American Society of Tropical Medicine and Hygiene.)

The Alere Filariasis Test Strip (FTS) is a qualitative, point-of-care diagnostic tool that detects Wuchereria bancrofti circulating filarial antigen (CFA) in human blood, serum, or plasma. The Global Program to Eliminate Lymphatic Filariasis employs the FTS for mapping filariasis-endemic areas and assessing the success of elimination efforts. The objective of this study was to explore the relationship between the intensity of positive test lines obtained by FTS with CFA levels as determined by enzyme-linked immunosorbent assay (ELISA) with blood and plasma samples from 188 individuals who live in a filariasis-endemic area. The intensity of the FTS test line was assessed visually to provide a semiquantitative score (visual Filariasis Test Strip [vFTS]), and line intensity was measured with a portable spectrodensitometer (quantitative Filariasis Test Strip [qFTS]). These results were compared with antigen levels measured by ELISA in plasma from the same subjects. qFTS measurements were highly correlated with vFTS scores (ρ = 0.94; P < 0.001) and with plasma CFA levels (ρ = 0.91; P < 0.001). Thus, qFTS assessment is a convenient method for quantifying W. bancrofti CFA levels in human blood, which are correlated with adult worm burdens. This tool may be useful for assessing the impact of treatment on adult filarial worms in individuals and communities., (© The American Society of Tropical Medicine and Hygiene.)

Implementation of mass drug administration (MDA) with ivermectin plus albendazole (ALB) for lymphatic filariasis (LF) has been delayed in central Africa because of the risk of serious adverse events in subjects with high Loa loa microfilaremia. We conducted a community trial to assess the impact of semiannual MDA with ALB (400 mg) alone on LF and soil-transmitted helminth (STH) infections in the Republic of Congo. Evaluation at 12 months showed that ALB MDA had not significantly reduced Wuchereria bancrofti antigenemia or microfilaria (mf) rates in the community (from 17.3% to 16.6% and from 5.3% to 4.2%, respectively). However, the geometric mean mf count in mf-positive subjects was reduced from 202.2 to 80.9 mf/mL (60% reduction, P = 0.01). The effect of ALB was impressive in 38 subjects who were mf-positive at baseline and retested at 12 months: 37% had total mf clearance, and individual mf densities were reduced by 73.0%. MDA also dramatically reduced the hookworm infection rate in the community from 6.5% to 0.6% (91% reduction), with less impressive effects on Ascaris and Trichuris. These preliminary results suggest that semiannual community MDA with ALB is a promising strategy for controlling LF and STH in areas with coendemic loiasis., (© The American Society of Tropical Medicine and Hygiene.)

Background: Little is known regarding risk factors for lymphatic filariasis (LF) in Central Africa. We studied the epidemiology of LF in an endemic village in the Republic of Congo., Methods: Dependent variables were Wuchereria bancrofti antigenemia (ICT card test) and microfilaremia (night blood smears). The following factors were investigated: sex, age, bed net, latrines, source of water, uptake of anthelmintic drugs, hunting/fishing activities, and occasionally sleeping in the bush. Mixed multivariate logistic regression models were used., Results: 134 of 774 subjects aged ≥ 5 years (17.3%) had W. bancrofti antigenemia and 41 (5.3%) had microfilaremia (mf). Infection rates increased with age up to roughly 20 years and remained stable thereafter. Multivariate analysis of antigenemia demonstrated an increased risk for males (OR = 2.0 [1.3-3.0]) and for people who hunt or fish (OR = 1.5 [1.0-2.4]) and a protective effect of latrines (OR = 0.5 [0.4-0.8]). Among males, those hunting or fishing at night had an increased risk for antigenemia (OR = 1.9 [1.1-3.5]), and use of latrines was protective (OR = 0.5 [0.3-0.9]). For females, bed nets were protective (OR = 0.4 [0.1-0.9]), and there was a strong household effect (intraclass correlation coefficient [ICC]: 0.24). When mf was used as the dependent variable, males had a higher risk for infection (OR = 5.4 [2.1-13.4]), latrines had a protective effect (OR = 0.4 [0.1-0.9]) and there was a marked household effect (ICC = 0.49)., Conclusions: Age, sex, and occupation-dependent exposure to mosquitoes were important risk factors for infection with W. bancrofti in this study. It is likely that men often acquire infection in high transmission areas outside of the village, while children and women are infected in areas with lower transmission inside or near the village. Additional studies are needed to determine whether these findings apply to other areas in Central Africa.