B J A Du Plessis

Publications of B J A Du Plessis

• Foot-and-mouth disease control using vaccination: South African experience.

  Authors: G K Brückner, W Vosloo, M Cloete, B Dungu, B J A Du Plessis

  Developments in biologicals. 02/2004; 119:51-62.

  South Africa has zoned status from the Office International des Epizooties (OIE) with the largest part of the country being foot-and-mouth disease (FMD)-free without vaccination. Outbreaks in thisSouth Africa has zoned status from the Office International des Epizooties (OIE) with the largest part of the country being foot-and-mouth disease (FMD)-free without vaccination. Outbreaks in this zone are handled differently from outbreaks in the control zones, which do not affect the export status of the country. However, the different socio-economic groupings need to be considered when reaching control decisions and in this regard, the country has been challenged with unique foot-and-mouth disease (FMD) control options. Vaccination has been shown to be effective both in ensuring that disease does not spread from the endemic to the free zone, as well as controlling outbreaks in the free zone. New adjuvants that claim to illicit longer lasting immunity have been tested with antigens derived from the SAT serotypes and animals were challenged one year post vaccination to determine the level of protection. However, even with vaccines that provide immunity for more than a year, an annual vaccination campaign will most probably not be acceptable in the buffer zone where calving occurs throughout the year.

• Foot and mouth disease: the experience of South Africa.

  Authors: G K Brückner, W Vosloo, B J A Du Plessis, P E L G Kloeck, L Connoway, M D Ekron, D B Weaver, C J Dickason, F J Schreuder, T Marais, M E Mogajane

  Revue scientifique et technique (International Office of Epizootics). 01/2003; 21(3):751-64.

  Foot and mouth disease (FMD) is endemic in African buffalo (Syncerus caffer) in the Kruger National Park (KNP) and surrounding game parks in South Africa. The last outbreak of the disease in domesticFoot and mouth disease (FMD) is endemic in African buffalo (Syncerus caffer) in the Kruger National Park (KNP) and surrounding game parks in South Africa. The last outbreak of the disease in domestic stock outside the FMD control zone occurred in 1957. Due to the success in containing the disease, the country was accorded zone freedom from FMD without vaccination by the Office International des Epizooties (OIE: World organisation for animal health) in 1995. This status was lost in September 2000 when the first-ever recorded case of serotype O in South Africa was diagnosed in a piggery in KwaZulu-Natal after the illegal feeding of untreated swill. In November 2000, an outbreak of FMD caused by serotype South African Territories (SAT) 1 was diagnosed in a feedlot within the free zone of Mpumalanga Province. The SAT 1 outbreak was traced to cattle in the FMD control zone south of the KNP after the game-proof fence surrounding the KNP was severely damaged by floods. This enabled buffalo to come into direct contact with cattle outside the KNP. A further outbreak caused by SAT 2 was diagnosed within the FMD control zone in February 2001, also as a result of buffalo having escaped from the KNP. All these outbreaks were successfully contained, with the re-instatement of zone freedom from FMD without vaccination by the OIE in May 2002. These outbreaks made it necessary to re-examine the methods of control and containment of FMD that have been practised for many years and which are in line with accepted international practices. The authors describe the rationale for the different control strategies that were followed, the need for a multidisciplinary approach to disease control, the interface between control and technological and diagnostic support and the lessons learned. Some suggestions for future control strategies are also offered.

• Ixodid ticks on cattle belonging to small-scale farmers at 4 communal grazing areas in South Africa.

  Authors: N R Bryson, G A Tice, I G Horak, C G Stewart, B J A du Plessis

  Journal of the South African Veterinary Association. 10/2002; 73(3):98-103.

  Ixodid ticks were collected during the period September 1991 to August 1993 from cattle belonging to small-scale farmers utilising 4 communal grazing areas. Three of these were in North West ProvinceIxodid ticks were collected during the period September 1991 to August 1993 from cattle belonging to small-scale farmers utilising 4 communal grazing areas. Three of these were in North West Province and 1 in Mpumalanga province, South Africa. Ten tick species were collected in North West Province and 7 in Mpumalanga. The adults of Amblyomma hebraeum, Rhipicephalus appendiculatus and Rhipicephalus evertsi evertsi were most numerous in North West Province, while in Mpumalanga Boophilus decoloratus comprised more than 75% of the total population. Amblyomma hebraeum was present on all grazing areas, and heavy infestations of adults occurred during the period October to May on 1 of these. Few B. decoloratus were collected in North West Province, chiefly because the sampling method was inadequate, and most of these were present during early summer (October to December) and late summer and autumn (March to May). The initially low population of B. decoloratus in Mpumalanga increased substantially towards the conclusion of the survey, probably because of the cessation of dipping. Boophilus microplus was present in small numbers on 2 grazing areas in the North West Province. Adult Hyalomma marginatum rufipes reached peak numbers from December to February and Hyalomma truncatum from February to April in the North West Province. Only H. marginatum rufipes was collected in Mpumalanga. Rhipicephalus appendiculatus was present on all the grazing areas, with most adults present from December to April. Most adult Rhipicephalus evertsi evertsi were collected from September to April and Rhipicephalus simus was present during the period October-April.

• Ixodid ticks on indigenous goats owned by small-scale farmers in four communal grazing areas in South Africa.

  Authors: N R Bryson, G A Tice, I G Horak, C G Stewart, B J A du Plessis

  Journal of the South African Veterinary Association. 04/2002; 73(1):26-30.

  Indigenous goats belonging to small-scale farmers in 4 communal grazing areas in South Africa were sampled for ixodid ticks during the period September 1991 to May 1993. Three of these areas were inIndigenous goats belonging to small-scale farmers in 4 communal grazing areas in South Africa were sampled for ixodid ticks during the period September 1991 to May 1993. Three of these areas were in the North West Province (Rietgat, Madinyane and Bethany), and one in Mpumalanga Province (Geluk). No tick control was practised unless requested by the owners. Seven ixodid tick species, of which the majority were immature ticks, were collected from the goats in North West Province. Amblyomma hebraeum was the most numerous of these, followed by Rhipicephalus evertsi evertsi and Rhipicephalus appendiculatus. Substantially more ticks were collected from goats at Rietgat than at the Madinyane and Bethany grazing areas. Five tick species were collected at Geluk and R. evertsi evertsi comprised more than 95 % of the total population. At Rietgat and Geluk A. hebraeum nymphs were present on goats throughout the year, while most R appendiculatus nymphs were collected during September and October 1991 and most adults during January and February 1992. At both Rietgat and Geluk most immature R. evertsi evertsi were collected from spring to late summer, while adults were present throughout the year.