Onchocerciasis in Gilgel Ghibe River valley Southwest Ethiopia

Objective: To determine the prevalence of onchocerciasis and the entomological transmission indices such as the parous rate and annual transmission potential (ATP).Setting: Gilgel Ghibe village, Gilgel Ghibe River Valley Southwest Ethiopia between April 1994 and March 1995.Subjects: Two hundred twenty eight subjects of the total 400 population in Gilgel Ghibe village were subjected to parasitological and clinical examinations.Method: Two skin snips per person were taken and examined for microfilariae of Onchocerca volvulus. Fly collections were done from dawn to dusk from human baits seated in pairs at four representative sites at the river bank and away from the river bank. Flies were dissected for parity and infections with O. volvulus larvae.Results: Among the 228 people examined, the prevalence of the disease was low (17%), being higher in males (19%) than in females (14%). The geometric mean of microfilarial density was 11.1 (range, 1-132) mf per skin snip. Itching followed by pigmentary changes were the most common clinical signs and symptoms. The predominant anthropophilic blackfly species was Simulium (Edwardsellum) damnosum s.l. The annual parous rate and ATP were 74.7% and 1669.5, respectively, being higher at the river bank than at sites further away suggesting a greater risk of infection by the river side.Conclusion: The low prevalence of onchocerciasis in Gilgel Ghibe area vis-a-vis the high ATP level could be due to the possible presence of bovine onchocerciasis in the area. Further studies employing molecular techniques are thus required to identify O. volvulus from other filariae in flies

Prevalence of soil transmitted nematodes on Nukufetau, a remote Pacific island in Tuvalu

BACKGROUND: The population of Nukufetau, a remote coral atoll island in Tuvalu in the Western Pacific, received annual mass drug administration (MDA) of diethylcarbamazine and albendazole under the Pacific Elimination of Lymphatic Filariasis program in 2001, 2002 and 2003, with the last MDA occurring six months before a cross-sectional survey of the whole population for soil transmitted helminths (STH). METHODS: A cross-sectional survey in May 2004 recruited 206 residents (35.2% of the population) who provided a single faecal sample that was preserved, concentrated and examined microscopically. RESULTS: Overall prevalence of STH was 69.9%; only hookworm and Trichuris trichiura were diagnosed. Trichuris was present in 68.4% with intensity of infection being light in 56.3%, medium in 11.7% and heavy in 0.5%. Hookworm occurred in 11.7% with intensity of infection 11.2% being light and medium in 0.5%. Twenty individuals (9.7%) had dual infections. The prevalence of Trichuris was constant across all ages while the prevalence of hookworm was significantly lower in residents below 30 years of age. In the age group 5–12 years comparison of results with a 2001 survey [1] suggested that the prevalence of STH has declined minimally, due to sustained high prevalence of Trichuris, while hookworm has declined dramatically from 34.4% to 1.6%. CONCLUSION: The results of this survey suggest that although the MDA appears to have reduced hookworm prevalence in residents below 30 years of age, there has been minimal effect on Trichuris prevalence. An integrated program to control STH is required

Impact of Long-Term Treatment with Ivermectin on the Prevalence and Intensity of Soil-Transmitted Helminth Infections

Soil-transmitted helminth (intestinal worm) infections are very common in developing countries and are an important cause of illness. Mass de-worming treatments of school children are an important strategy to reduce illness caused by these infections in communities without access to clean water and sanitation. Few studies have examined the effect of repeated mass treatments in the long-term in controlling these infections. The objective of the present study was to assess the impact of the drug ivermectin used for the control of onchocerciasis (river blindness), that has important effects against intestinal worms, on the epidemiology of intestinal worms in children when administered repeatedly for 15–17 years. We compared the epidemiology of infections between children living in communities that received ivermectin with communities that never received the drug. The data suggest that ivermectin has important differential effects on intestinal worms with a greater impact on infections with Trichuris trichiura and little impact on Ascaris lumbricoides and hookworms infections. Our data suggest that long-term ivermectin treatments may provide health benefits through effects on T. trichiura infections but that the addition of second de-worming drug such as albendazole may be required for the control of other intestinal worm infections

Effects of Annual Mass Treatment with Ivermectin for Onchocerciasis on the Prevalence of Intestinal Helminths

We evaluated the effect of annual ivermectin (IV) distribution for onchocerciasis on the prevalence of soil transmitted helminth (STH) infections in school-aged (SAC) and preschool-aged (PAC) children by comparing children in villages that had received treatment for 13 years to those from socioeconomically similar villages in untreated areas. We enrolled 1,031 SAC and 211 PAC for Kato Katz examinations. Treated areas had a lower prevalence of Ascaris (SAC: 3% versus 12%, P < 0.0001; PAC: 3% versus 10%, P < 0.051) and Trichuris (SAC: 6% versus 10%, P = 0.012; PAC: 1% versus 8%, P = 0.019), but not hookworm (SAC: 38% versus 42%, P = 0.20; PAC: 21% versus 27%, P = 0.30). The prevalence of Ascaris or Trichuris in treated areas was below the WHO threshold for mass antihelminthic treatment (MDA), but not for hookworm. We conclude that benzimidazole MDA in IV treatment areas is indicated to effectively control hookworm