Validation of the rapid assessment procedure for loiasis (RAPLOA) in the democratic republic of Congo

Abstract

BackgroundA simple method called RAPLOA, to rapidly assess what proportion of people in a community are infected with L. loa and hence which communities are at high risk of severe adverse reactions following ivermectin treatment, was developed in Cameroon and Nigeria. The method needed further validation in other geographical and cultural contexts before its application in all endemic countries. The present study was designed to validate RAPLOA in two regions in the North East and South West of the Democratic Republic of Congo.MethodsIn each study region, villages were selected from different bio-ecological zones in order to cover a wide range of loiasis endemicity. In each selected community, 80 people above the age of 15 years were interviewed for a history of eye worm (migration of adult L. loa under the conjunctiva of the eye) and parasitologically examined for the presence and intensity of L. loa infection. In total, 8100 individuals from 99 villages were enrolled into the study.ResultsThe results confirmed the findings of the original RAPLOA study: i) the eye worm phenomenon was well-known in all endemic areas, ii) there was a clear relationship between the prevalence of eye worm history and the prevalence and intensity of L. loa microfilaraemia, and iii) using a threshold of 40%, the prevalence of eye worm history was a sensitive and specific indicator of high-risk communities.ConclusionFollowing this successful validation, RAPLOA was recommended for the assessment of loiasis endemicity in areas targeted for ivermectin treatment by lymphatic filariasis and onchocerciasis control programmes.

Using Community-Level Prevalence of Loa loa Infection to Predict the Proportion of Highly-Infected Individuals: Statistical Modelling to Support Lymphatic Filariasis and Onchocerciasis Elimination Programs

“…The epidemiological data available were obtained from two field studies in village communities (henceforth villages) conducted in the West and East provinces of Cameroon between July and August 2001 [13] as well as in the Republic of the Congo and the Bas-Congo and Orientale provinces of the Democratic Republic of the Congo (DRC) between January and May 2004 [14]. Fig 1 shows the locations of all sampled villages.…”

“…The Cameroon data contain the estimated Loa loa infection level (parasites/ml of blood) in samples from between 24 and 229 individuals in a total of 73 villages [13]. The data from the Republic of the Congo and the DRC contain the same information from between 27 and 102 individuals in a total of 149 villages, together with the bio-ecological zones of each village (forest, mosaic forest savannah, savannah) [14]. Collectively, the two data-sets cover 19 049 individuals from 222 villages.…”

Ivermectin to reduce malaria transmission: a research agenda for a promising new tool for elimination

“…These reactions are closely related to the microfilarial load and are due to parasite lysis rather than drug toxicity [38]. Rapid assessment of loasis is now recommended before ivermectin MDA in Loa -endemic areas [39]. …”

Onchocerciasis control in the Democratic Republic of Congo (DRC): challenges in a post‐war environment

“…Rapid screening for loiasis may be performed by asking subjects whether they have a history of eye worm (rapid assessment procedure for loiasis, RAPLOA), and the results are then subjected to a spatial analysis to produce prevalence of infection maps (Wanji et al . ). Little was known about the geographical distribution of loiasis within DRC at the start of the CDTI projects but, more recently, large‐scale implementation of RAPLOA in 11 endemic countries, including DRC, has provided a more reliable global map of the disease (Zouré et al .…”