ORIGINAL RESEARCH

 

Molecular monitoring of African swine fever virus using surveys targeted at adult Ornithodoros ticks: A re-evaluation of Mkuze Game Reserve, South Africa

 

 

L.F. Arnqt^{I, II}; J.T. Du Toit^{I, III}; A.D.S. Bastos^{I, IV}

^IMammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0002 South Africa
^IICurrent address: Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110 South Africa
^IIICurrent address: Department of Wildland Resources, Utah State University, Logan, UT 84322-5230, USA
^IVARC-Onderstepoort Veterinary Institute, Private Bag X05, Onderstepoort, 0110 South Africa

 

 

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ABSTRACT

The Mkuze Game Reserve (MGR), in north-eastern KwaZulu-Natal Province, South Africa is an African swine fever virus (ASF) controlled area. In a survey conducted in 1978, ASF prevalence in warthogs and Ornithodoros ticks in MGR was determined to be 2 % and 0.06 %, respectively. These values, acknowledged as being unusually low compared to other East and southern African ASF-positive sylvatic-cycle host populations, have not been assessed since. The availability of a sensitive PCR-based virus detection method, developed specifically for the sylvatic tampan host, prompted a re-evaluation of ASF virus (ASFV) prevalence in MGR ticks. Of the 98 warthog burrows inspected for Ornithodoros presence, 59 (60.2 %>) were found to contain tampans and tick sampling was significantly male-biased. Whilst gender sampling-bias is not unusual, the 27 °% increase in infestation rate of warthog burrows since the 1978 survey is noteworthy as it anticipates a concomitant increase in ASFV prevalence, particularly in light of the high proportion (75 %>) of adult ticks sampled. However, despite DNA integrity being confirmed by internal control amplification of the host 16S gene, PCR screening failed to detect ASFV. These results suggest that ASFV has either disappeared from MGR or if present, is localized, occurring at exceptionally low levels. Further extensive surveys are required to establish the ASFV status of sylvatic hosts in this controlled area.

Keywords: African swine fever virus, Mkuze Game Reserve, Ornithodoros porcinus, PCR, warthog

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Accepted for publication 13 April 2009-Editor

 

 

* Author to whom correspondence is to be directed. E-mail: ad-bastos@zoology.up.ac.za