Presence ofWuchereria bancroftimicrofilaremia despite 7 years of annual ivermectin monotherapy mass drug administration for onchocerciasis control: a study in north-west Ethiopia

Abstract

Background: There is considerable interest in determining whether mass drug administration (MDA) with ivermectin for onchocerciasis control will eliminate coendemic lymphatic filariasis (LF). The objective of this study was to determine the prevalence of LF microfilaremia in onchocerciasis endemic districts that had received 7 years of MDA with ivermectin. Method: Three villages with a 2010 LF circulating antigenaemia prevalence (determined in a mapping exercise using immunochromatography tests) ranging from 23 to 56% were surveyed for the presence of Wuchereria bancrofti microfilaria (mf) in 2012. These villages had been treated with ivermectin MDA for onchocerciasis with reported total population coverage of ≥65%. A total of 774 residents aged 2 years and above, of both genders, provided 60 μl nocturnal blood samples between 10 pm and 2 am. Standard thick smears were prepared and examined microscopically after Giemsa staining for the presence of W. bancrofti mf. Results: The mean mf prevalence was 4.7% (village range 1.1-11.0%). The mean mf density was 9.8 mf/60 μl (village range 9-13.1) among the positive individuals. Children in the 2-4-year-old and 5-9-year-old age groups were infected suggesting transmission occurred during the MDA period. A village level review of MDA treatment coverage records showed an average total population coverage of 66.4% over a 7-year period, but with a considerable range of annual coverage (43.0-89.9%). In addition, village level treatment coverage data were missing from the village with the highest mf prevalence (11%) for 2 of the 7 years. Conclusion: 7 years of annual mass treatment with ivermectin monotherapy for onchocerciasis did not interrupt LF transmission. In expanding the onchocerciasis ivermectin MDA programme to include LF, albendazole should be added and treatment coverage improved.

<p>Mapping and monitoring for a lymphatic filariasis elimination program: a systematic review</p>

“…It was found that inspite of 6 rounds of MDA, Mf prevalence was 3.3%. The authors had suggested mass distribution of DEC medicated salt as an adjunct to hasten elimination of infection in these islands. 7 South East AsiaIndonesiaDewi et al, 2015109Three communities (one non endemic,one passed TAS,one failed TAS)1,543 children6–7Ab prevalenceThis study provided the epidemiological support for the use of Ab levels to determine “critical cut-off thresholds” in Brugia spp. areas.…”

“…One study assessed the possibility of integrating antibody testing for LF and oncho, which has highlighted the complexities that may arise in making a decision on stopping MDA particularly in LF-oncho co-endemic areas of Africa 111. Another study109 observed that 7 years of monotherapy with ivermectin has not reduced Mf prevalence in a oncho-LF co-endemic area and therefore to achieve significant reduction, the authors suggested that albendazole be added to the program particularly in LF endemic areas. In another oncho-LF co-endemic area118 the study showed that while Mf and Ag rates were reduced by 83% and 67%, the mosquito infection and infectivity rates were reduced by 86% and 76% compared to the baseline.…”

Evaluation of Lymphatic Filariasis and Onchocerciasis in Three Senegalese Districts Treated for Onchocerciasis with Ivermectin

“…The baseline mapping results showed antigenemia prevalence ranging from 23 to 56% in these villages. After seven years of ivermectin treatment the mean microfilaremia prevalence in the three villages was still 4.7% [10]. These studies suggest that annual ivermectin may reduce prevalence of infection but may not be sufficient to interrupt transmission.…”

Effects of temperature, pH and curing on the viability of <i>Sarcocystis,</i> a Japanese sika deer (<i>Cervus Nippon centralis</i>) parasite, and the inactivation of their diarrheal toxin

“…For parasites, Trichinosis, Toxoplasmosis and Onchocerciacis are common transmissible parasitic diseases from wild animals, including deer, and a number of studies on their characterization and prevention have been performed [ 4 , 11 , 16 ]. Regarding Sarcocystis (Protozoa: Apicomplexa), many species have already been identified in other animals, such as S. cruzi , S. hirsuta and S. bovihominis in cattle; S. miescheriana, S. porcifelis and S. suihominis in pigs and S. tenella and S. mihoensis in sheep [ 1 , 10 , 15 , 24 , 33 , 35 , 36 ].…”