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Biomedical subjects

D I Simpson

Publications and source records attributed to D I Simpson.

At least 55 records · Page 3Linked to original sources
PubMed1979

Characterization of two Chikungunya virus variants.

The stability of virulence and plaque size of two variants of Chikungunya virus (genus Alphavirus) were examined. Mouse pathogenicity did not coincide with infective virus levels in the brain. An increase in the average survival times of mice receiving a lethal dose of the variant which allowed prolonged survival at high doses and harvested late after infection was observed. Studies in Vero cells suggested that the number of infective virus particles produced per cell was lower with the small plaque variant, though these cells were selective for this clone. On the other hand suckling mice or antisera favoured a more virulent large plaque variant.

Animals↗
PubMed1979

Investigation of the ecology of Soldado virus on Puffin Island, North Wales.

The prevalence of Soldado (SOL) virus and SOL virus antibodies was investigated on immature sea birds and the argasid tick Ornithodoros (Alectorobius) maritimus collected on Puffin Island, North Wales. No SOL virus was recovered from 133 bird sera, but 2 of the birds exhibited neutralizing antibodies against SOL virus. Nine of 27 tick pools (226 individuals) and 34 of 173 ticks tested individually proved to be infected with SOL virus.

Animals↗
PubMed1978

The isolation of a Bwamba virus variant from man in Western Kenya.

A bwamba group virus was isolated from the blood of a febrile child on the Kano Plain, Kenya. The isolate (NY-45), closely resembling Bwamba, established infection in both Anopheles gambiae and Mansonia uniformis. Neither the Bwamba nor the Pongola prototype strains grew in both species. In gel-diffusion tests NY-45 virus passaged through mosquitoes exhibited a line of identity with Pongola antiserum. In contrast no cross-reaction was observed with NY-45 virus which had not previously been passaged through mosquitoes.

Adult↗
PubMed1978

The pathology of experimental Ebola virus infection in monkeys.

Six rhesus and two vervet monkeys were infected intraperitoneally with Ebola virus. They developed an acute haemorrhagic fever with skin rash 4 days later and died 6--12 days after infection. Histopathological lesions of acute necrosis were present in the liver, spleen, lymph nodes, lungs and testes. The presence of fibrin thrombi in several organs was suggestive of the occurrence of disseminated intravascular coagulation during the infection.

Animals↗
PubMed1978

Ebola haemorrhagic fever: experimental infection of monkeys.

Experimental infection of rhesus and vervet monkeys with Ebola virus produced a uniformly fatal illness. The course of the disease resembled that found in man with weight loss, anorexia, fever, haemorrhages and skin rash being frequently seen. Viraemia was obvious within two days of infection and persisted until death which occurred between days five and eight. Virus was found in high concentrations in several organs but particularly in the liver, spleen, and lungs.

Animals↗
PubMed1978

Ebola virus: a comparison, at ultrastructural level, of the behaviour of the Sudan and Zaire strains in monkeys.

Histopathological and electron microscopical examination of human liver specimens collected during the Ebola haemorrhagic fever outbreaks in Zaire and Sudan indicated that Zairean strains of the virus produced more extensive lesions. Experimental infection of rhesus monkeys wiht Zairean and Sudanese strains of Ebola virus produced similar changes to those found in man. In Zairean strain infections large numbers of virus particles were found in the liver, lung and spleen accompanied by extensive necrosis in the spleen. In Sudan strain infections particles were found only in the liver and in greatly reduced numbers. The main distinction lay in the high proportion of aberrant particles found with the Sudanese strain. The possibility of these being defective particles is discussed.

Animals↗
PubMed1978

Viral haemorrhagic fevers of man.

This article reviews the current state of knowledge on the viral haemorrhagic fevers that infect man, namely smallpox, chikungunya fever, dengue fever, Rift Valley fever, yellow fever, Crimean haemorrhagic fever, Kyasanur Forest disease, Omsk haemorrhagic fever, Argentinian haemorrhagic fever (Junin virus), Bolivian haemorrhagic fever (Machupo virus), Lassa fever, haemorrhagic fever with renal syndrome, and Marburg and Ebola virus diseases.

Animals↗
PubMed1977

Marburg fever.

Explore the source record for details and available documents.

Animals↗
PubMed1977

Arbovirus isolations from, and serological studies on, wild and domestic vertebrates from Kano Plain, Kenya.

Arbovirus infection and presence of haemagglutination-inhibiting antibodies in small mammals, birds and livestock were examined over a period of five years on the Kano Plain in western Kenya. Eleven isolations were made from mammals and birds. The viruses were identified as Arumowot and Germiston while three different agents could not be shown to be related to 188 African arboviruses. Prevalence of antibodies against arboviruses suspected of occurring in the area was generally low.

Animal Population Groups↗
PubMed1977

Arbovirus isolations from mosquitoes: Kano Plain, Kenya.

Arbovirus isolation attempts on 324,486 mosquitoes captured over a four-year period on the Kano Plain, Kenya, yielded 15 isolates including Pongola (six strains), Ilesha (three strains), Germiston (two strains), Sindbis (one strain), Barur (one strain) and two viruses which could not be characterized. Mansonia uniformis, Anopheles gambiae and Culex antennatus constituted 70% of the total collection and accounted for all of the isolates except one, which came from Anopheles funestus.

Animals↗
PubMed1976

Arbovirus infections in Sarawak: the role of the domestic pig.

The possible role of pigs as arbovirus maintenance hosts and their importance as amplifier hosts was studied. Blood samples from 464 pigs of all ages collected in 1962 and 1964 were tested against 10 arboviruses. Antibodies to Japanese encephalitis and Getah viruses were particularly prevalent and their calculated monthly infection rates were 19-5% and 13-3% respectively. In 1969, 447 pigs were bled monthly throughout the year and the infection rates for Japanese encephalitis virus were calculated in pigs during the first year of life. Infection rates were not uniform throughout the year; the rate increases as the pig grew older and there was a marked seasonal increase in the infection rate in the period from November to January. This coincided with the seasonal major population peak of Culex tritaeniorhynchus following intense breeding of this mosquito prior to rice planting. It is suggested that, in Sarawak, the pig acts as a maintenance host of Japanese encephalitis in a cycle involving C. gelidus mosquitoes and also acts as an important amplifier host towards the end of the year in a cycle involving C. tritaeniorhynchus. It is further suggested that Getah virus is maintained in a similar cycle between C. tritaeniorhynchus and pigs.

Age Factors↗
PubMed1976

Antigenic relationships of alphaviruses by a simple micro-culture cross-neutralization method.

A cross-neutralization study of 22 alphaviruses disclosed two major antigenic complexes and two viruses that were distinct from all the others. Cross-reactions were common but were restricted within the complexes. Sub-groupings within a complex were also shown, and some viruses proved to be indistinguishable by neutralization testing. The results generally paralleled previously reported data. Investigations were carried out, using BHK 2I cells in a micro tissue-culture system, on all available alphaviruses.

Antigens, Viral↗
PubMed1975

Arbovirus infections in Sarawak, October 1968-February 1970: GETAH virus isolations from mosquitoes.

14 strains of Getah virus were isolated from a variety of mosquito species collected in Sarawak between October 1968 and February 1970. Ten strains were isolated from C. tritaeniorhynchus 7 of them at K. Tijirak. Single strains were isolated from C. gelidus, C. pseudovishnui, M. bonneae/dives and Aanopheles species. 6 of the isolates were obtained in October 1968 when Japanese encephalitis, Tembusu and Sindbis viruses were also very active. The available evidence suggest that Getah virus in Sarawak is maintained in a cycle similar to that of Japanese encephalitis virus and involves C. tritaeniorhynchus, C. gelidus and domestic pigs.

Arbovirus Infections↗
PubMed1975

Arbovirus infections in Sarawak, October 1968-February 1970: human serological studies in a land Dyak village.

449 human sera collected in a Land Dyak village were tested for antibodies to 11 arboviruses. Japanese encephalitis and dengue virus antibodies were particularly prevalent. The rates of infection with these viruses were estimated to be 5-2% per annum for Japanese encephalitis, 8-8% for dengue 1 and 4-3% for dengue 2. Chikungunya virus antibodies were quite common with an annual infection rate of the order of 5% per annum. Infections with other Group A and B and Bunyamwera group viruses were generally at a low level.

Adolescent↗
PubMed1975

Arbovirus infections in Sarawak, October 1968--February 1970 Tembusu and Sindbis virus isolations from mosquitoes.

Thirty isolations of Tembusu virus and four of Sindbis virus were obtained from approximately 280 000 mosquitoes collected between October 1968 and February 1970 in Sarawak, particularly from K. Tijirak, a Land Dyak village 19 miles South of Kuching. Twenty-two isolations of Tembusu virus and two of Sindbis virus were from Culex tritaeniorhynchus; two of Tembusu virus and two of Sindbis virus came from Culex gelidus. Tembusu virus was active throughout the year at K. Tijirak, the highest infection rates in C. tritaeniorhynchus being in January-March and May-August, when the C. tritaeniorhynchus population was declining and ageing. These results confirm that C. tritaeniorhynchus is the principal arthopod host of Tembusu virus in Sarawak. Antibody studies suggest that birds, particularly domestic fowl, are probably vertebrate maintenance hosts of Tembusu and Sindbis viruses in Sarawak.

Animals↗