Assessment of Loiasis and Outcomes of Ivermectin Masstreatment in Ijebu-North, Nigeria

Abstract

A total of 286 individuals from 3 selected communities (Areedi-Aje, Ipakodo/Ojokodo, and Ijebu-Igbo) of Ijebu-North, southwestern Nigeria were examined for Loa loa microfilaremia using finger prick blood smear, between December 2008 and March 2009. Rapid assessment procedure for loiasis (RAPLOA) was used to obtain information, from 187 Ijebu-Igbo residents, on adverse reactions experienced from retrospective treatments with ivermectin and history of eye worm. Only 33.9% of the respondents reported having had a history of eye worm while 33.2% had microfilaremia. The demographic factor of gender was not significant determinants of the prevalence (P>0.05) while age was significant (P<0.05). The highest prevalence of eye worm history and microfilaremia were recorded in 61-70 and 15-20 years of age categories, respectively. Ijebu-Igbo had 27.3% eye worm history, 32.1% microfilaremia, and the highest intensity of 140 microfilariae (mf)/ml. Ipakodo area had the highest eye worm history of 54.4% and the highest intensity of 420 mf/ml. Areedi-Aje had the highest occurrence of 45.2% microfilaremia and the highest intensity of 460 mf/ml. Predictably, Areedi-Aje and Ipakodo areas were high risk communities. The low intensity of L. loa infection with an insignificant (2.1%; P>0.05) adverse reactions from 187 subjects involved in the retrospective ivermectin administration confirmed that ivermectin delivery may be considered safe. The community-directed treatment with ivermectin (CDTI) programme was most probably responsible for the low prevalence and intensity.

In Southern Nigeria Loa loa Blood Microfilaria Density is Very Low Even in Areas with High Prevalence of Loiasis: Results of a Survey Using the New LoaScope Technology

“…An important contribution of our study is that we were able to assess residents of 28 Nigerian villages where RAPLOA results were above the 40% threshold, and found no very high-density infections there. Our results are consistent with a report by Hassan et al, 26 who studied a village in southwest Nigeria (Ikpakodo) with 54% eye worm history where the highest L. loa mf count was only 420 mf/mL. Our village sample included an expanded range of RAPLOA prevalence (10-67%) that mitigated our risk of missing very high-density infections if they occurred in villages with RAPLOA < 40% that are not believed to be at risk of CNS-AEs.…”