Audit of the community-directed treatment with ivermectin (CDTI) for onchocerciasis and factors associated with adherence in three regions of Cameroon

Abstract

BackgroundAfter 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.ResultsIn 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).ConclusionsDespite 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.

Differential susceptibility of Onchocerca volvulus microfilaria to ivermectin in two areas of contrasting history of mass drug administration in Cameroon: Relevance of microscopy and molecular techniques for the monitoring of skin microfilarial repopulation within six months of direct observed treatment

“…Similar concerns were reported recently following the detection of Loa loa Mf in skin snips in Cameroon [15]. Moreover, microscopy may not be able to detect infection in patients with very low micro laridermia [10]. In addition, the insu cient sensitivity of skin snip microscopy has been demonstrated in a report from Uganda and Ethiopia where 84 of 853 samples were declared negative by microscopy were positive using polymerase chain reaction (PCR) and Melt-Curve Analysis (PCR-MCA) [11].…”

“…This could be due to the fact that the drug effect on the parasite population in Melong is more effective than on the parasite population in Ba a HD. Hence, treatment will lead to very low micro laridermia in the Melong HD which will further affect the poor sensitivity of microscopy as reported earlier [10].…”

“…Microscopic detection and identi cation of Mf, based on morphological characteristics [10,11] in skin snips remains the gold standard for the diagnosis of onchocerciasis in humans [12,13]. However, previous ndings have raised questions about the reliability of this method due to the presence of Mf of other species which can also reside in the skin.…”

“…In addition, the insu cient sensitivity of skin snip microscopy has been demonstrated in a report from Uganda and Ethiopia where 84 of 853 samples were declared negative by microscopy were positive using polymerase chain reaction (PCR) and Melt-Curve Analysis (PCR-MCA) [11]. The low sensitivity of microscopy can be more pronounced when people are treated with a micro laricide which will further lower the Mf density [10,11]. Conclusively, microscopy could be de ned as an imperfect gold standard.…”

“…Besides microscopy [10], immunological [17,18] and nucleic acid-based methods, speci cally PCR [19,20] and LAMP [21,22] have been used to diagnose O. volvulus in skin. Although there have been advances in the development of immunological methods involving detection of either antibody or antigen [17,18], cross-reactivity with other larial species has been reported [23].…”