Identification and genetic characterization of Trypanosoma congolense in domestic animals of Fontem in the South-West region of Cameroon.

To understand the circulation and the spread of Trypanosoma congolense genotypes in animals of Fontem in the southwest region of Cameroon, T. congolense forest and T. congolense savannah were investigated in 397 domestic animals in eight villages. Out of the 397 domestic animals, 86 (21.7%) were found infected by trypanosomes, using the capillary tube centrifugation test. The PCR with specific primers identified 163 (41.1%) and 81 (20.4%) animals infected by T. congolense forest and T. congolense savannah, respectively; showing for the first time the circulation of T. congolense savannah in the Fontem region. No infection with T. congolense savannah was found in pigs whereas goats and sheep were infected by T. congolense forest and/or T. congolense savannah. The prevalence of trypanosomes varied significantly amongst villages and animal species. The genotyping of T. congolense forest positive samples using microsatellites markers showed that multiple genotypes occurred in 27.2% (44/163) of animals sampled, whereas single genotypes were found in 73.8% (119/163) of samples. Some alleles were found in all animal species as well as in all villages and were responsible for major genotypes, whereas others (rare alleles) were identified only in some animals of few villages. These rare alleles were characteristic of specific genotypes, assimilated to minor genotypes which can be spread in the region through tsetse flies. The microsatellite markers show a low genetic variability and an absence of sub-structuration within T. congolense forest. The analysis of the microsatellite data revealed a predominant clonal reproduction within T. congolense forest. Pigs were the animal species with the highest number of different genotypes of T. congolense forest. They seem to play an important epidemiological role in the propagation and spread of different genotypes of T. congolense.