Detection of multiple drug-resistant Trypanosoma congolense populations in village cattle of south-east Mali

Abstract

BackgroundTsetse fly-transmitted African animal trypanosomosis causes annual losses that run into billions of dollars. The disease is assumed to cause hunger and poverty in most sub-Saharan countries since it represents a serious impediment to sustainable livestock production. Both a cross-sectional and a longitudinal study were carried out from November to December 2007 to evaluate trypanosomosis risk and susceptibility of trypanosomes to trypanocidal drug treatment in village cattle populations in south-east Mali.MethodsEight purposively selected villages participated in the study. In each village, eight traps deployed along drainage lines over 24hour duration were used to catch tsetse. One hundred systematically selected cattle in the study villages were examined for trypanosomes. All trypanosome-positive cattle were randomly allocated into two treatment groups: a group treated with 0.5 mg/kg bw. isometamidium chloride (ISMM) and a group treated with 3.5 mg/kg bw. diminazene aceturate (DIM). The cattle were monitored for trypanosomes at day 14 and 28 post-treatment.ResultsOf the 796 cattle examined, 125 (15.7%) were trypanosome-positive. Village trypanosome prevalences ranged between 11% and 19%. There were no significant (p > 0.05) differences in the village trypanosome prevalences. Trypanosoma congolense was the dominant trypanosome species accounting for 73% (91/125) of the infections and T. vivax the remainder. Twenty (31.7%) of the 63 cattle on 0.5 mg/kg bw. ISMM treatment were still positive14 days post-treatment. Of the 43 aparasitaemic cattle monitored to day 28, 25.6% (11) became parasitaemic, resulting in a cumulative failure rate of 49.2% (31/63). Trypanosoma congolense accounted for 77.4% (24/31) of failed ISMM treatments. The 62 cattle treated with 3.5 mg/kg bw. DIM resulted in 30.6% (19/62) failed treatments. Although 42.2% (19/45) of T. congolense positive cattle did not respond to DIM treatment, all T. vivax positive cattle responded positively to DIM treatment.ConclusionsThe overreliance on trypanocides in the control of trypanosomosis will ultimately lead to multiple drug-resistant trypanosome populations as detected in villages in south-east Mali rendering the use of drugs doubtful. Effective alternative methods for trypanosomosis control ought to substitute chemotherapy to ensure sustainable cattle production in these villages. Since there is no single strategy for containing trypanocidal drug resistance, promotion of an integrated approach combining proven trypanosomosis control approaches in high trypanosomosis risk areas is most desirous. The best-bet strategy this study recommended for areas with multiple drug resistance included area-wide community tsetse control, control of co-infections to exploit self-cure against resistant trypanosome populations and the rational use of trypanocidal drugs which should be urgently promoted at all levels as a way of containing or reversing resistance.

Sensitivity of Trypanosoma congolense field isolates in experimentally infected calves in Konso district, Southern Ethiopia to isomethamidium and diminazene

“…This observation is in accordance with the currently available information indicating the trypanocidal effects of treatment with Veridium ® in cattle (Stevenson et al, 2000). Delaying of Veridium ® treatment by 45 days after the administration of Diminasan ® was a reasonable process in light with the possible side effects that could be associated with the injection of the second drug in a short period following the administration of the first (Eisler et al, 2001;Stein et al, 2011;Mungube et al, 2012). The sensitivity of the isolates to Veridium ® is conclusive.…”

“…As there is an increasing number of case reports from other trypanosomosis endemic areas of Ethiopia, disclosing range of prevalence of T. congolense resistant to Diminasan ® and Veridium ® (Codjia et al, 1993;Mulugeta et al, 1997;Rowlands et al, 2001;Afework et al, 2004;Tewelde et al, 2004), the demonstration of resistance to Diminasan ® (about 33% from the present study) manifested by the current T. congolense isolates at Jarso, was unsureprisingly an expected outcome. Furthermore, it has been observed under longitudinal studies that there was an association between the initial trypanosome prevalence and the occurrence, and thus the degree, of drug resistance (Mungube et al, 2012).…”

“…Control of animal trypanosomosis is one of the key components to improve the productive opportunities of rural communities in tsetse-infested areas. This has been addressed using trypanocidal drugs which are limited in number and have been under extensive use for over 40 years with little or no regular monitoring (Stein et al, 2011;Chitanga et al, 2011;Mungube et al, 2012;Sow et al, 2012).…”

“…For instance trypanocidal drug resistance was observed for isometamidium chloride and diminazene aceturate against Trypanosoma congolense, Trypanosoma vivax and Trypanosoma evansi (Mungube et al, 2012;Sow et al, 2012;Kumar et al, 2012). The high infestation of lowlying areas by tsetse flies as well as T. congolense, T. vivax and T. bruceiwas also reported more than a decade back in Southern parts of Ethiopia (Abebe, 2005;Miruk et *Corresponding author.…”

The animal trypanosomiases and their chemotherapy: a review

“…The disease has devastating effects on the livelihoods of local farmers, for whom cattle represent not only a source of food (meat and milk), manure, and draught power, but have also fundamental social roles as ‘living banks’ and are used for social obligations (e.g. dowry and ritual use) (Swallow, 2000; Grace et al 2009; Mungube et al 2012). …”