Standardised tests in mice and cattle for the detection of drug resistancein tsetse-transmitted trypanosomes of African domestic cattle

Resistance to the drugs used to control African animal trypanosomosis is in creasingly recognised as a constraint to livestock production in sub-Sahara n Africa. The most commonly used tests for detection of trypanocidal drug r esistance are tests using mice or ruminants, but these suffer from lack of standardisation and hence it may be difficult to compare the results of dif ferent investigators. Tests in mice are less expensive than tests in rumina nts, but while tests in mice they may be useful as a general guide to resis tance in a geographic area they should not be extrapolated to cattle on an individual trypanosome level. Moreover, the commonly used protocols are too laborious for their application to large number of trypanosome isolates on an area-wide basis. This paper presents guidelines for standardised testin g of trypanocidal drugs in vivo, and introduces a simplified single-dose te st for use in mice, which is convenient for use in areas with limited labor atory facilities. The single-dose test is appropriate for characterisation of geographic areas in terms of trypanocidal drug resistance using large nu mbers of trypanosome isolates, for making comparisons between areas, and fo r monitoring changes in trypanocidal drug resistance over time. Multiple-do se tests may be used to determine the degree of resistance of individual st abilates to be determined precisely in mice are also described, but for log istical reasons these will rarely be conducted on more than a few stabilate s, and testing of a larger number of stabilates in the single-dose test wil l generally provide more useful information. Finally, we describe tests in cattle that may be used to determine the efficacy of recommended curative d oses of trypanocidal drugs for the treatment of infection with individual t rypanosome isolates, including Trypanosoma vivax, which is rarely infective for mice. (C) 2001 Elsevier Science B.V. All rights reserved.