Seasonal biting pattern of Simulium damnosum s.l and its implications on onchocerciasis treatment with ivermectin.

Background: The current control strategy adopted by African Programme for Onchocerciasis Control (APOC) is the mass distribution of ivermectin in all endemic areas for between 12-15 years. One of the major obstacles of the strategy, is the ability of the fly to migrate long distances and this brings about the possibility of flies migrating from uncontrolled areas to controlled areas.

Objective: To assess the impact of annual ivermectin treatment of onchocerciasis and to ascertain the seasonality of transmission and its impact on the current control strategy in the forest zone around a dam in Southern Nigeria.

Identification of the forest strain of Onchocerca volvulus using the polymerase chain reaction technique.

Annual mass treatment with ivermectin for 12-15 years in endemic communities is the control strategy adopted by the African Programme for Onchocerciasis Control (APOC) for the control of onchocerciasis in Nigeria. This long-term treatment necessitates the use of Polymerase Chain Reaction (PCR) for the proper identification of the Onchocerca species and strains in endemic areas and also for monitoring recrudescence of infection in areas where infection has been controlled. This study, which forms part of a larger study on transmission of onchocerciasis identifies the Onchocerca volvulus strain in Ondo state using the Polymerase Chain Reaction (PCR) technique.

Effect of aestivation of Biomphalaria pfeifferi on the survival and infectivity of Schistosoma mansoni cercariae.

Schistosoma mansoni cercariae from post-aestivated Biomphalaria pfeifferi remain motile for 20 hours after release. Thereafter, their activity decreases with age. The difference in mortality rate of cercariae from aestivated and non-aestivated B.

Infectivity and transmission dynamics of simulium damnosum s. 1 around Owena dam (Ondo State).

A twelve month study on the infectivity and transmission dynamics of simulium damnosum s.1 around Owena dam was conducted as part of a longitudinal study of onchocerciasis in the community living in the vicinity of the dam. A total of 3,133 flies (49.

Schistosoma mansoni: effect of aestivation on the intra-molluscan stages and the survival rate of infected Biomphalaria pfeifferi.

Following exposure to the miracidia of Schistosoma mansoni, Biomphalaria pfeifferi were induced to aestivate immediately ('0 h') or on days 7, 14 or 21 post-infection and then re-activated at various times. The proportions of snails found to be alive at weekly intervals after re-activation were found to be related to the length of time the snails had spent between infection and aestivation (I-A), varying from 100% (0 h) to 5% (21 days). The mean numbers of cercariae produced by the snails after re-activation also varied with I-A, being highest in those that aestivated immediately post-infection, and cercarial development was delayed by prolonged desiccation of the infected snails, the intra-molluscan development of S.