avian gyrovirus 2 and avirulent newcastle disease virus coinfection in a chicken flock with neurologic symptoms and high mortalities.a disease with severe neurologic symptoms caused 100% mortality in a small broiler operation in the gauteng province, south africa in late march 2013. routine diagnostic pcr testing failed to identify a possible cause of the outbreak; thus, samples were submitted for virus isolation, serology, and bacteriology. an avirulent newcastle disease virus (ndv) strain isolated was identified as a v4-like genotype 1 strain, by dna sequencing, with a cleavage site of 112gkqgr decrease l117. real-time reve ...201424758119
the ecology of west nile virus in south africa and the occurrence of outbreaks in humans.this paper reviews studies done on west nile virus (wnv) in south africa, mainly between 1962 and 1980 on the temperate inland plateau (highveld and karoo). the virus is maintained in an enzootic transmission cycle between feral birds and the ornithophilic mosquito culex univittatus. about 30 avian species have been shown to be involved without mortality. humans, and other mammals, although they may have antibodies, are considered blind-alleys in the transmission cycle except perhaps some dogs. ...200111797772
environmental temperature on the vector competence of culex univittatus (diptera: culicidae) for west nile virus.the effects of the extrinsic incubation temperature on the vector competence of culex univittatus theobald for west nile (wn) virus were studied. a mean titer of 7.0 log10 cpd50/ml of mosquito suspension was reached in orally infected mosquitoes after 11, 15, and 16 d of incubation at 26 and 30 degrees c and at fluctuating temperatures in an outside cage (mean temperature, 23.5 degrees c), respectively. in contrast, 22 and 58 d were required to reach the same titers at 18 and 14 degrees c, respe ...19938459423
sindbis and west nile virus infections in the witwatersrand-pretoria region.from mid-december 1983 until mid-april 1984, there was an epidemic of sindbis (sin) virus infection in the witwatersrand-pretoria region in which hundreds of human cases were diagnosed clinically. twenty-eight of these diagnoses were confirmed in the laboratory by seroconversion as being infections with sin virus, and 5 cases of infection with west nile (wn) virus were also found. attempts to isolate virus from 66 patients, mainly from serum specimens, were unsuccessful. infection rates for the ...19863016922
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