Cattle breeding, trypanosomosis prevalence and drug resistance in Northern Togo.

African Animal Trypanosomosis (AAT) is a major disease of cattle in Togo and its control is essentially based on chemotherapy. However, because of excessive use of trypanocides during the past decades, chemo-resistance in the parasites has developed. In order to assess the current situation of AAT and resistance to trypanocidal drugs in Northern Togo, a study was conducted on cattle from December 2012 to August 2013 in the regions of Kara and Savanes. An initial cross-sectional survey was carried out in 40 villages using the Haematocrit Centrifugation Technique (HCT). Out of these, 5 villages with a trypanosome prevalence of >10% were selected for a block treatment study (BT) with diminazene diaceturate (DA: 3.5mg/kg for a 14-day follow-up) and isometamidium chloride (ISM: 0.5mg/kg for a 28-day follow-up). Positive blood samples collected during the parasitological surveys and an equivalent number of negatives were further analyzed by PCR-RFLP for trypanosome species confirmation and molecular diagnosis of resistance to DA in Trypanosoma congolense. The results from 1883 bovine blood samples confirmed a high overall trypanosome prevalence of 10.8% in Northern Togo. PCR-RFLP revealed that T. congolense is the dominant pathogenic trypanosome species (50.5%) followed by T. vivax (27.3%), and T. brucei (16.2%). The BT showed varying levels of treatment failures ranging from 0 to 30% and from 0 to 50% for DA and for ISM respectively, suggesting the existence of resistant trypanosome populations in the study area. Our results show that AAT still represents a major obstacle to the development of cattle husbandry in Northern Togo. In areas of high AAT risk, a community-based integrated strategy combining vector control, rational use of trypanocidal drugs and improving the general condition of the animals is recommended to decision makers.

Drug quality analysis through high performance liquid chromatography of isometamidium chloride hydrochloride and diminazene diaceturate purchased from official and unofficial sources in Northern Togo.

Trypanocidal drugs remain the most accessible and thus commonly used means of controlling tsetse transmitted animal African trypanosomosis. In Togo, trypanocides are sold on official as well as unofficial markets, but the quality of these trypanocides is undocumented so a drug quality assessment study was conducted from May 2013 to June 2014. Trypanocides supplied by European, Indian and Chinese pharmaceutical companies and sold on official and unofficial markets in Togo were purchased. In total fifty-two trypanocides were obtained, 24 of these samples from official markets and 28 from unofficial markets made up of a total of 36 diminazene diaceturate and 16 isometamidium chloride hydrochloride samples. The samples were analysed in the reference laboratory of the OIE (World Organisation for Animal Health), Laboratory for the Control of Veterinary Medicines (LACOMEV) in Dakar which uses galenic testing and high performance liquid chromatography (HPLC) testing as standard reference analysis methods. The results revealed a high proportion of trypanocides of sub-standard quality on the Togolese market: 40% were non-compliant to these quality reference standards. All of the HPLC non-compliant samples contained lower amounts of active ingredient compared to the concentration specified on the packaging. Non-compliance was higher in samples from the unofficial (53.57%) than from the official markets (25%; p=0.04).The main drug manufacturers, mostly of French origin in the study area, supply quality drugs through the official legal distribution circuit. Products of other origins mostly found on illegal markets present a significantly lower quality.

The area-wide epidemiology of bovine trypanosomosis and its impact on mixed farming in subhumid West Africa; a case study in Togo.

This paper reports on an area wide study of all major variables determining the expression of trypanosomosis in cattle in the subhumid eco-zone of West Africa, taking Togo as an example. To enable systematic area-wide sampling, the country was divided in 311 grid-squares of 0.125 x 0.125 sides. Cross-sectional surveys were then conducted to generate maps or digital layers on cattle density, herd structure, ownership and breed. These data layers, except for the breed data, were subjected to a cluster analysis in order to define spatial patterns in animal husbandry systems. This analysis revealed two main systems: one is oriented towards integration with crop-agriculture and a second towards investment in cattle. These two systems could be further characterised by incorporating breed data. Zebu cattle and their crossbreeds are more favoured in the second system. The breed distribution map shows the actual situation but also serves to predict the outcome of progressive crossbreeding. An area wide trypanosomosis survey allowed the production of prevalence maps for Trypanosoma congolense, T. vivax and the associated packed cell volume (PCV) values. A simple curvi-linear relationship was established between vector density and disease prevalence. The regression between disease prevalence and PCV for taurine and zebu plus crossbreeds separately, revealed that taurine cattle maintain a comparatively high PCV level particularly in high prevalence scenarios. The relationship between the average herd PCV and cattle density suggests that herd PCV value may provide a mirror for the number of animals not kept because of the prevailing risk. The regression between agricultural intensity and cattle density subsequently in areas with decreasing herd PCV values reveals that the level of integration of cattle in crop production decreases with a decreasing PCV. Thus, despite the presence of taurine animals in Togo, the omnipresence of tsetse in particular Glossina tachinoides, remains a major obstacle to cattle raising and indirectly mixed farming development and intensification. It is argued that only with the present type of wide scale, spatial studies it becomes possible to clarify all the major variables influencing the expression of trypanosomosis. Spatial epidemiological studies at a macro level may form the basis for area wide trypanosomosis control in West Africa.