ECOLOGY OF PLAGUE IN AFRICA - RESPONSE OF INDIGENOUS WILD RODENTS TO EXPERIMENTAL PLAGUE INFECTION

  • 1 January 1983
    • journal article
    • research article
    • Vol. 61  (2) , 339-344
Abstract
The Mastomys natalensis sp. complex, subdivided into genetically distinct species having diploid chromosome numbers 2n = 32 and 2n = 36, is a reservoir for plague. Whether these sibling species and 3 other rodent species have different potential as reservoirs for plague was studied. M. natalensis (2n = 32) was significantly more resistant to experimental plague infection (50% survived inoculation with 120,000 Yersinia pseudotuberculosis ssp. pestis) than was M. coucha (2n = 36) (none of which survived doses of 190 Y. pseudotuberculosis ssp. pestis). In descending order of resistance were M. natalensis, Aethomys chrysophilus, M. coucha, Tatera leucogaster and A. namaquensis. No A. namaquensis survived inoculation of .gtoreq. 10 plague bacilli. Previous reports on susceptibility to plague or other infections, based exclusively on findings in the universally distributed laboratory-bred Mastomys, are thus not necessarily applicable to the M. natalensis sp. as a whole, but probably only to M. coucha. The Y. pseudotuberculosis ssp. pestis fraction-1 passive hemagglutination test appeared to be relatively insensitive in that only 5 of 47 animals surviving experimental plague infection showed specific antibodies 6 wk after challenge. The geographic distribution of human plague in southern Africa corresponded closely with that of the plague-susceptible species, M. coucha; the resistant species, M. natalensis, predominates in areas where human plague has not been recorded. The role of A. namaquensis in the ecology of plague needs to be carefully studied; its possible importance in plague research should be investigated further.