After more than a decade of community-directed treatment with ivermectin (CDTI) in Centre and Littoral Regions of Cameroon, onchocerciasis endemicity was still high in some communities according to the 2011 epidemiological evaluations. Some corrective measures were undertaken to improve the CDTI process and therefore reduce the burden of the disease. The objective of the present study was to assess the progress made towards the elimination of onchocerciasis in the Centre 1 and Littoral 2 CDTI projects where the worst performances were found in 2011. To this end, a cross-sectional survey was conducted in April 2015 in eight communities in two health districts (HD), Bafia in Centre 1 and Yabassi in Littoral 2, chosen because assessed at baseline and in 2011. All volunteers living for at least five years in the community, aged five years or more, underwent clinical and parasitological examinations. Individual compliance to ivermectin treatment was also assessed. Analyses of data were weighted proportionally to age and gender distribution in the population. In the Bafia and Yabassi HD, 514 and 242 individuals were examined with a mean age of 35.1 (standard deviation, SD: 20.7) and 44.6 (SD: 16.3) years, respectively. In the Bafia HD, the weighted prevalences varied from 24.4 to 57.0 % for microfilaridermia and from 3.6 to 37.4 % for nodule presence across the surveyed communities. The community microfilarial load (CMFL), expressed in microfilariae/skin snip (mf/ss), significantly dropped from 20.84–114.50 mf/ss in 1991 to 0.31–1.62 mf/ss in 2015 in all the surveyed communities. In the Yabassi HD, the weighted prevalences varied from 12.3 to 59.3 % for microfilaridermia and from 1.5 to 3.7 % for nodule presence across the surveyed communities, while a significant drop was observed in CMFL, from 20.40–28.50 mf/ss in 1999 to 0.48–1.74 mf/ss in 2015. The 2014 weighted therapeutic coverage of participants varied from 65.8 % (95 % CI: 58.4–73.2) in Yabassi HD, to 68.0 % (95 % CI: 63.3–72.7) in Bafia HD, with important variations among communities. After more than 15 years of CDTI, onchocerciasis is still mesoendemic in the surveyed communities. Further studies targeting therapeutic coverage, socio-anthropological considerations of CDTI implementation and entomological studies would bring more insights to the persistence of the disease as observed in the present study.

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.

Loiasis is a parasitic infection endemic in the African rain forest caused by the filarial nematode Loa loa. Loiasis can be co-endemic with onchocerciasis and/or lymphatic filariasis. Ivermectin, the drug used in the control of these diseases, can induce serious adverse reactions in patients with high L loa microfilaraemia (LLM). A drug is needed which can lower LLM below the level that represents a risk so that ivermectin mass treatment to support onchocerciasis and lymphatic filariasis elimination can be implemented safely. Sixty men and women from a loiasis endemic area in Cameroon were randomized after stratification by screening LLM (≤30000, 30001–50000, >50000) to three treatment arms: two doses albendazole followed by 4 doses matching placebo (n = 20), six doses albendazole (n = 20) albendazole or 6 doses matching placebo (n = 20) administered every two months. LLM was measured before each treatment and 14, 18, 21 and 24 months after the first treatment. Monitoring for adverse events occurred three and seven days as well as 2 months after each treatment. None of the adverse events recorded were considered treatment related. The percentages of participants with ≥ 50% decrease in LLM from pre-treatment for ≥ 4 months were 53%, 17% and 11% in the 6-dose, 2-dose and placebo treatment arms, respectively. The difference between the 6-dose and the placebo arm was significant (p = 0.01). The percentages of participants with LLM < 8100 mf/ml for ≥4 months were 21%, 11% and 0% in the 6-dose, 2-dose and placebo treatment arms, respectively. The 6-dose regimen reduced LLM significantly, but the reduction was insufficient to eliminate the risk of severe and/or serious adverse reactions during ivermectin mass drug administration in loiasis co-endemic areas. Loiasis is a big obstacle for the elimination of onchocerciasis and lymphatic filariasis in Central Africa in areas where loiasis is endemic. In these areas, some subjects who are heavily infected (microfilaraemia > 30 000 microfilariae/ml blood) can develop severe and serious adverse reactions to ivermectin. In rare cases, these have been fatal. A way of preventing these reactions could be to administer a treatment that decreases the microfilareamia in all subjects below the risk level before mass treatment with ivermectin. Building on results of previous studies, this randomised placebo-controlled trial evaluated the efficacy and safety of two or six doses of albendazole administered every two months on the microfilaraemia of Loa loa. Six doses led to a decrease in microfilaraemia by at least 50% for at least four months in 53% of participants. However, it did not reduce the microfilaraemia below the risk level in all participants. Therefore, this regimen has not sufficient efficacy to prevent severe adverse reactions to ivermectin.

After more than 15 years of community-directed treatment with ivermectin (CDTI) in the Centre 1, Littoral 2 and West CDTI projects in Cameroon, the epidemiological evaluation conducted in 2011 revealed that onchocerciasis endemicity was still high in some communities. To investigate the potential reasons explaining this high endemicity, a cluster coverage survey was conducted in April-May 2015 in three health districts (HD), to assess the implementation of the CDTI, the 2014 therapeutic coverage and the five-year adherence to treatment. A two-stage cluster design was considered during analyses, with data weighted proportionally to age and gender distribution in the population. In the three HDs, 69 community leaders, 762 heads of households, 83 community drug distributors (CDD) and 2942 household members were interviewed. The CDTI organization and the involvement of heads of households were in average weak, with 84.0% (95% CI: 81.2–86.4%) of them who had not participated in activities during the 2014 mass drug administration (MDA). On average, six of ten community leaders declared that the period of treatment was decided by the health personnel while the CDDs selection was made during a community meeting for only 43.4% of them. The 2014 weighted therapeutic coverage was 64.1% (95% CI: 56.8–70.9%), with no significant difference in the three HDs. The survey coverages were lower than the reported coverages with a significant difference varying from 14.1% to 22.0%. Among those aged 10 years and above, 57.8% (95% CI: 50.2–65.1%) declared having taken the treatment each time during the last five MDAs with no significant difference among HDs, while 9.8% (95% CI: 7.5–12.8%) declared that they had never taken the drug. In multivariate analysis, the most important factors associated with the five-year adherence to treatment were high involvement in CDTI and age (40+ years). Despite more than 15 years of CDTI, there was still weak community participation and ownership, a lower coverage than reported and an average five-year adherence in the surveyed HDs. The reinforcement of the community ownership by the Ministry of Public Health officials and the timely procurement of ivermectin as requested by the communities are some measures that should be implemented to improve the therapeutic coverage, adherence to treatment and hence achieve onchocerciasis elimination. Further anthropological and entomological studies would provide better insights into our understanding of the persistence of the disease in these three CDTI projects.

After more than a decade of community-directed treatment with ivermectin (CDTI) in the West Region of Cameroon, epidemiological evaluation conducted in 2011 showed that onchocerciasis endemicity was still high in some communities. The conceptual framework for onchocerciasis elimination recommends in such case, to conduct additional phase 1A surveys at intervals of three to four years. Therefore, to assess the progress made towards the elimination of onchocerciasis in the West CDTI projects, we conducted a cross-sectional survey in May 2015 in 15 unevaluated communities where the highest baseline endemicity level were found in 1996. All volunteers living for at least five years in the community, aged five years or more, underwent clinical and parasitological examinations. Individual adherence to ivermectin treatment was also assessed. Analyses of data were weighted proportionally to age and gender distribution in the population. The mean age was 28.4 ± 22.2 years and there were 55% of women among the 2058 individuals examined. The weighted prevalences were 5.5%, 2.1% and 1.7% for microfilaridermia, nodule and cutaneous signs, respectively. The weighted microfilaridermia prevalences varied from 4.0 in 5–9 years old to 11.6% in 40–49 years old. In the 30 children under 10 years examined in Makouopsap, the weighted prevalences were 49.9% for microfilaridermia and 13.3% for nodule. In surveyed communities, the weighted prevalences varied from 0 to 41.6% for microfilaridermia, with 11 (73.3%) communities having <5%. Except Makouopsap which had 41.6%, all the surveyed communities were below 15% for microfilaridermia prevalence. The community microfilarial load (CMFL) expressed in microfilariae/skin snip (mf/ss), also significantly dropped by 98–100%, from 3.75–33.16 mf/ss in 1996 to 0–0.94 mf/ss in 2015. The weighted therapeutic coverage in 2014 was 69.4% and the 5 years’ adherence was only 39.3% among participants. After more than 15 years of CDTI, there is an important progress towards the elimination of onchocerciasis in the communities surveyed. Innovative strategy like semi-annual ivermectin treatment plus vector control or the adjunction of a vector control strategy to the current annual treatment should be implemented in the bordering districts of the Centre and West Regions, as well as in other parts of the country with persistent high prevalences in the sight of onchocerciasis elimination.

Lymphatic filariasis (LF) is one of the most debilitating neglected tropical diseases (NTDs). It still presents as an important public health problem in many countries in the tropics. In Cameroon, where many NTDs are endemic, only scant data describing the situation regarding LF epidemiology was available. The aim of this study was to describe the current situation regarding LF infection in Cameroon, and to map this infection and accurately delineate areas where mass drug administration (MDA) was required. The endemicity status and distribution of LF was assessed in eight of the ten Regions of Cameroon by a rapid-format card test for detection of W. bancrofti antigen (immunochromatographic test, ICT). The baseline data required to monitor the effectiveness of MDA was collected by assessing microfilariaemia in nocturnal calibrated thick blood smears in sentinel sites selected in the health districts where ICT positivity rate was ≥ 1%. Among the 120 health districts visited in the eight Regions during ICT survey, 106 (88.3%) were found to be endemic for LF (i.e. had ICT positivity rate ≥ 1%), with infection rate from 1.0% (95% CI: 0.2–5.5) to 20.0% (95% CI: 10–30). The overall infection rate during the night blood survey was 0.11% (95% CI: 0.08–0.16) in 11 health districts out of the 106 surveyed; the arithmetic mean for microfilaria density was 1.19 mf/ml (95% CI: 0.13–2.26) for the total population examined. ICT card test results showed that LF was endemic in all the Regions and in about 90% of the health districts surveyed. All of these health districts qualified for MDA (i.e. ICT positivity rate ≥ 1%). Microfilariaemia data collected as part of this study provided the national program with baseline data (sentinel sites) necessary to measure the impact of MDA on the endemicity level and transmission of LF important for the 2020 deadline for global elimination. Lymphatic filariasis, commonly known as elephantiasis, is a parasitic disease caused by the filarial nematodes Wuchereria bancrofti, Brugia malayi and Brugia timori. It is widely distributed in the tropics where it results in a chronic and debilitating disease. Nearly 1.4 billion people in 73 countries worldwide are threatened by lymphatic filariasis, with an estimated 120 million people infected, and more than 40 million disfigured and incapacitated by the disease. Mass drug administration of appropriate chemotherapeutic agents has been successful in eliminating the infection in some endemic areas supporting the contention that global elimination of the infection has become feasible. Before targeting lymphatic filariasis for elimination, it is necessary to map its distribution in order to identify areas where treatment is required. In this present study, two surveys were carried out in each of eight Regions of Cameroon to assess the endemicity status and intensity of the infection. Lymphatic filariasis was found to be endemic in all Regions surveyed and in almost all the constituent health districts. As virtually all of these Regions and health districts were found to be eligible for MDA treatments, baseline data were also acquired that can be used by the national program for the evaluation of the success of mass drug administration on the endemicity and transmission of the disease.