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.

Salmonella typhi infection in Schistosoma mansoni infected mice.

Aspects of the biology of Salmonella typhi in concurrent infection with Schistosoma mansoni in mice was studied. 0.2ml of 1 x 10(6) per S.

A modified medium for the in vitro cultivation of trypanosomes.

A modified medium (ME-99) for the in vitro cultivation of trypanosomes was developed and evaluated in our laboratory. The medium comprised of Eagle MEM as a base and various components of medium 199 not found in MEM. Trypanosoma brucei brucei, T.

Ethnographic study on childhood diarrhoeal diseases in a rural Nigerian community.

Mothers in thirty households in a rural Nigerian community were subjected to ethnographic studies on food handling practices as they relate to diarrhoeal diseases in children. The study had a first phase of three open-ended unstructured interviews each lasting about 2 hours and a second phase of direct observations on food handling practices during preparation, administration and storage by mothers. Results indicated that as many as 20 (66.

Bacteriological study of cooked ogi (fermented cereal weaning food) and its potential safety in a rural Nigerian community.

Thirty households with children receiving the fermented cereal food ogi were selected randomly from Ajara, a rural community in Lagos State, Nigeria. Eighty-one samples of ogi were collected from these households at the time of administration to the children. The degree of bacteriological contamination and pH values of the cooked ogi samples were determined.

Study on the pH of ogi, Nigerian fermented weaning food, and its effect on enteropathogenic Escherichia coli, Salmonella typhi and Salmonella paratyphi.

The pH values of both cooked and uncooked ogi samples were determined and the survival of nalidixic acid-resistant enteropathogenic Escherichia coli OB 26 34/20, Salmonella typhi and Salmonella paratyphi A when seeded into cooked ogi were studied. The pH values of ogi ranged from pH 3.0 to 3.

Effect of ultraviolet radiation on survival, infectivity and maturation of Schistosoma mansoni cercariae.

S. mansoni cercariae exposed to ultraviolet radiation for 1, 3, 5, 10 and 20 s as well as non-irradiated cercariae remained actively motile 30 min post-irradiation. Thereafter the activity decreased with increasing dose level of radiation and age of cercariae.

Effect of host-diet inadequacy on the course of infection of plasmodium yoelii Nigeriensis.

Investigations were conducted into the course of infection of plasmodium yoelli nigeriensis in mice fed on an inadequate diet. It was found that mice fed on a '1/2' diet were able to withstand infection with the parasite better than mice fed on a full diet or a 1/4' diet. The haemoglobin value of mice fed on a full, '1/2' and '1/4' diets dropped by 67.

Investigation of Cryptosporidium in relation to other intestinal parasites at the Lagos University Teaching Hospital, Lagos.

Cryptosporidium spp is a coccidian protozoan which has recently been reported as a possible important aetiological agent of diarrhoea, especially in immunocompromised hosts such as patients with acquired immuno-deficiency syndrome (AIDS). In the present report, 890 stool specimens of patients including diarrhoea cases submitted for parasitologic laboratory investigation at the Lagos University Teaching Hospital from January to December 1986 were specifically screened for Cryptosporidium oocysts. There was no confirmed case of crystosporidioisis in-the 12-month study period.

Experimental infections of Plasmodium yoelii nigeriensis in mice and rats, and hosts' reactions.

In investigations into the course of infection of Plasmodium yoelii nigeriensis in rats and mice, it was found that adult mice, baby mice and baby rats were susceptible to the infection, while adult rats were totally refractive. The infection was rapidly fatal in baby and adult mice but was maintained with a low parasitaemia and tolerated by baby rats until the animals were 7 weeks old, after which they eradicated the infection totally. Although the adult rats did not exhibit any parasitaemia, there was a decrease in their haemoglobin and packed cell volume values.

Effect of stress conditions on the course of trophozoite-induced Plasmodium yoelii nigeriensis in mice recently cured of a previous infection.

The effect of stress conditions on the course of trophozoite-induced Plasmodium yoelii nigeriensis in mice recently treated for a previous infection was studied. It was found that when the mice were infected with up to 5943 parasites within 6 days of treating a previous infection, no patent infection was recorded. However, an inoculum of 7924 parasites induced parasitaemia, with a long period of prepatency and a short course of infection before the parasites died out.

Laboratory transmission of Schistosoma mansoni in brackish waters; survival and infectivity of cercariae.

Schistosoma mansoni cercariae were exposed to various dilutions of sea water, both in the absence and in the presence of mice. It was found that whereas 100% and 75% sea water were lethal to the parasites, the parasites survived in lower concentrations of sea water. The lower the concentration the longer was the survival time.

The epidemiology of Entamoeba histolytica in a Nigerian urban population.

Microscopic examination of multiple faeces samples of 2 825 persons was carried out in the Metropolitan Lagos. Overall prevalence of Entamoeba histolytica was 11.2%.

Human Ancylostoma infections in Nigeria.

An estimate of the proportion of infections with Ancylostoma duodenale and Necator americanus by the examination of larvae collected from the stools of 220 persons infected with hookworm was made. Fifty-nine per cent of the infections were due to N. americanus only: A.

Age and sex distribution of infections with Entamoeba histolytica and Giardia intestinalis in the Lagos population.

Stool samples were collected from 2,099 persons and examined for parasites: 9.5 percent were infected with Entamoeba histolytica, 7.9 percent were infected with Giardia intestinalis and 15.

The role of the house fly (Musca domestica) in the dissemination of hookworm.

Eggs and larvae of Ancylostoma caninum were recovered from the crop, mid-gut and hind-gut of Musca domestica; only larvae were recovered from the vomitus and one dead infective larva was recovered from the faeces on one occasion. All eggs recovered from the gut hatched after incubation for 48 hours. Up to 319 eggs and 1485 larvae were recovered from the legs of experimentally contaminated flies.