Cattle are a major reservoir of Shiga toxin‐producing Escherichia coli. This study investigated the occurrence of seven major STEC serogroups including O157, O145, O103, O121, O111, O45 and O26 among 578 STEC isolates previously recovered from 559 cattle. The isolates were characterized for serotype and major virulence genes. Polymerase chain reaction revealed that 41.7% (241/578) of isolates belonged to STEC O157, O145, O103, O121, O45 and O26, and 33 distinct serotypes. The 241 isolates corresponded to 16.5% (92/559) of cattle that were STEC positive. The prevalence of cattle that tested positive for at least one of the six serogroups across the five farms was variable ranging from 2.9% to 43.4%. Occurrence rates for individual serogroups were as follows: STEC O26 was found in 10.2% (57/559); O45 in 2.9% (16/559); O145 in 2.5% (14/559); O157 in 1.4% (8/559); O121 in 1.1% (6/559); and O103 in 0.4% (2/559). The following proportions of virulence genes were observed: stx1, 69.3% (167/241); stx2, 96.3% (232/241); eaeA, 7.1% (17/241); ehxA, 92.5% (223/241); and both stx1 and stx2, 62.2% (150/241) of isolates. These findings are evidence that cattle in South Africa carry STEC that belong to six major STEC serogroups commonly incriminated in human disease. However, only a subset of serotypes associated with these serogroups were clinically relevant in human disease. Most STEC isolates carried stx1, stx2 and ehxA but lacked eaeA, a major STEC virulence factor in human disease.
Du Preez, J.H.; Hattingh, P.J.; Giesecke, W.H.; Eisenberg, B.E.; Verwoerd, Daniel Wynand(Published by the Government Printer, Pretoria., 1990)
Temperature-humidity index (THI) values applicable to South Africa and Namibia have been established during this investigation for each month of the year by means of computerized modelling and mapping techniques.
The data ...
Owen, N.C.; Du Toit, R.M.; Howell, P.G.; Jansen B.C.(Pretoria : The Government Printer, 1965)
Bluetongue viruses were isolated from five clinically healthy bovines exposed to
natural infection over two consecutive bluetongue seasons. The isolated viruses
were typed by serum-virus neutralization and found to ...
In Northern Sotho, a separate colour lexicon is distinguished, containing terms which are believed to be used
exclusively as colour terms to describe not only the colours, but also the colour patterning found among ...