Evaluation of the vectorial competence of Glossina brevipalpis in the transmission of Trypanosoma congolense- savannah type, in the Matutuíne District, Maputo Province, Mozambique

African Animal Trypanosomosis (AAT) is a parasitic disease caused by trypanosome species, posing a major challenge to animal health and production in Africa. In the Matutuíne District, southern Mozambique, where Glossina brevipalpis is prevalent, AAT is endemic. Previous research conducted in South Africa suggested that G . brevipalpis plays a marginal role in the transmission of Trypanosoma congolense . However, considering the wide distribution of G. brevipalpis in Southeast Africa and the major epidemiological implications of the aforementioned observations, this study was designed to re-assess the vectorial competence of G. brevipalpis in the transmission of T. congolense- savannah type.

The research involved 915 G. brevipalpis flies, fed six times on two cattle infected with T. congolense . After 48 hours, the flies were later fed on a non-infected animal to clean the proboscis, followed by extended feeding on four susceptible cattle for 22 days. These five clean animals were monitored for 60 days based on body temperature, packed cell volume, buffy coat technique and polymerase chain reaction. In the meantime, flies were dissected weekly to observe the development of trypanosomes in the midgut and proboscis. To discard any possible mechanical transmission by G. brevipalpis 48 hours after an infected blood meal, 97 flies from a colony were fed once on two infected cattle and once on a susceptible bovine. The Spearman correlation and Mann-Whitney U tests were used to analyse the data.

Results showed that the four susceptible cattle became infected with T. congolense , while the animal used for proboscis cleaning and discard any mechanical transmission remained uninfected. Dissections revealed that 89% of flies were positive for trypanosome through microscopy and 100% through PCR. These findings confirm that G. brevipalpis is a competent biological vector for transmitting T. congolense, challenging earlier assumptions and emphasizing its role in AAT dynamics.