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G S Nelson

Publications and source records attributed to G S Nelson.

At least 109 records · Page 6Linked to original sources
PubMed1970

Onchocerciasis.

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Africa↗
PubMed1970

Studies on heterologous immunity in schistosomiasis. 4. Heterologous schistosome immunity in cattle.

Previous studies have shown that when mice and monkeys are infected with bovine schistosomes they develop a considerable degree of heterologous immunity against subsequent challenge with Schistosoma mansoni. The present report describes a study on the reverse effect in which calves were first exposed to cercariae of S. mansoni and then challenged with cercariae of S. mattheei. The calves developed patent infections with S. mansoni, excreting viable eggs in the faeces, and it is suggested that cattle may be a source of infection to man under natural conditions. The immunizing effect of exposure to S. mansoni was demonstrated by a reduction in the S. mattheei egg load and adult worm burden in the immunized, as compared with the control, animals. The results suggest that previous exposure of cattle to S. mansoni may reduce the severity of bovine schistosomiasis in endemic areas.

Animals↗
PubMed1969

Studies on heterologous immunity in schistosomiasis. 3. Further observations on heterologous immunity in mice.

Previous studies on heterologous immunity in mice and rhesus monkeys have shown that immunization with Schistosoma bovis, S. mattheei or S. rodhaini cercariae can limit the severity of infection resulting from subsequent challenge with S. mansoni. The present report describes further evidence of the protection afforded by heterologous immunization. It has been demonstrated that mice immunized with S. mattheei can withstand S. mansoni infections that are lethal to normal mice and that the degree of immunity developed is influenced by the level of maturation and the duration of the initial infection, the size and number of immunizing doses, the route of exposure and the sex of the parasite.

Animals↗
PubMed1968

Studies on heterologous immunity in schistosomiasis. 2. Heterologous schistosome immunity in rhesus monkeys.

Previous studies on heterologous immunity in mice have indicated that Schistosoma bovis and S. mattheei could be used to limit the severity of infection resulting from subsequent challenge by S. mansoni. These observations have now been extended to study the immunizing effect in rhesus monkeys of both S. mattheei and S. bovis.The bovine schistosomes were shown to be relatively non-pathogenic in rhesus monkeys. Immunization with 1000-2000 cercariae resulted in a marked reduction in the pathogenic effect of subsequent challenge with S. mansoni. This effect was demonstrated by a decrease in the worm load and tissue egg densities in 10 immunized monkeys as compared with 5 control animals.There was no correlation between fluorescent antibody titres and the intensity of infection or the degree of acquired immunity. There was a cross-reaction between S. mansoni and the bovine schistosomes.It is suggested that natural heterologous immunity (zooprophylaxis) may be of considerable epidemiological importance in determining the severity of schistosomiasis in man.

Animals↗
PubMed1968

Studies on heterologous immunity in schistosomiasis. I. Heterologous schistosome immunity in mice.

Epidemiological and experimental studies indicate that heterologous immunity resulting from exposure to bovine and other animal schistosomes might be of some importance in determining the relative severity of schistosome infection in man in different parts of the world. The reduction in the severity of a disease process, resulting from exposure to relatively non-pathogenic infections, has been called "zooprophylaxis".The observations recorded in the present paper on the interaction in mice of Schistosoma bovis, S. mattheei and S. rodhaini with S. mansoni provide further evidence of this phenomenon. The most potent immunizing effect was produced with S. bovis and S. mattheei, which resulted in a reduction in the expected S. mansoni egg load of 74% and 85.7%, respectively.It is suggested that zooprophylaxis may be an important factor in limiting the severity of schistosomiasis in areas of Africa where bovine and other animal schistosomes are prevalent. The relatively more severe nature of the disease in Egypt and Brazil may be in part due to the absence of concomitant transmission of bovine schistosomes.

Animals↗