An update of the tsetse fly (Diptera: Glossinidae) distribution and African animal trypanosomosis prevalence in north-eastern KwaZulu-Natal, South Africa

Abstract

An unpredicted outbreak of African animal trypanosomosis or nagana in 1990 in north-eastern KwaZulu-Natal necessitated an emergency control programme, utilising the extensive cattle-dipping system in the area, as well as a reassessment of the tsetse and trypanosomosis problem in the province. Since 1990, sporadic blood sampling of cattle at the dip tanks in the nagana-infested areas were undertaken to identify trypanosome species involved and to determine the infection prevalence in cattle. The distribution and species composition of the tsetse populations in the area were also investigated. From November 2005 to November 2007 selected dip tanks were surveyed for trypanosome infection prevalence. During April 2005 to August 2009 the distribution and abundance of tsetse populations were assessed with odour-baited H traps. The tsetse and trypanosome distribution maps were updated and potential correlations between tsetse apparent densities (ADs) and the prevalence of trypanosomosis were assessed. Glossina brevipalpis Newstead and Glossina austeni Newstead were recorded in locations where they have not previously been collected. No significant correlation between tsetse relative abundance and nagana prevalence was found, which indicated complex interactions between tsetse fly presence and disease prevalence. This was epitomised by data that indicated that despite large differences in the ADs of G. austeni and G. brevipalpis, trypanosome infection prevalence was similar in all three districts in the area. This study clearly indicated that both tsetse species play significant roles in trypanosome transmission and that it will be essential that any control strategy, which aims at sustainable management of the disease, should target both species.

Gamma Irradiation and Male Glossina austeni Mating Performance

“…Two tsetse species, Glossina brevipalpis and G. austeni, are present in an area of 16,000 km 2 in the north eastern part of the KwaZulu-Natal Province in South Africa [39,40], and both populations extend into southern Mozambique and G. austeni into eSwatini [41][42][43]. Although G. austeni is considered to be the more competent vector for the transmission of Trypanosoma parasites, it has been shown that both species can transmit Trypanosoma congolense and Trypanosoma vivax in South Africa [44][45][46][47].…”

Evaluation of radiation sensitivity and mating performance of Glossina brevipalpis males

“…In South Africa, Glossina brevipalpis Newstead and Glossina austeni Newstead are the vectors of Trypanosoma congolense and Trypanosoma vivax [4–7] that cause AAT in an area of about 16 000 km 2 in the north eastern parts of the KwaZulu-Natal Province [8,9]. Because of the limited options available for controlling the parasite, i.e.…”

“…brevipalpis extends from Ethiopia in the north to KwaZulu-Natal, South Africa in the south and is present in Somalia, Uganda, Kenya, Rwanda, Burundi, Tanzania, Malawi, Zambia, Zimbabwe and Mozambique [38]. Although this species belongs to the fusca group of tsetse flies, considered of less or no epidemiological importance for livestock, it was recently shown that the role of this species in transmitting AAT in South Africa should not be underestimated [9]. It has become evident that removing only G .…”

“…austeni from KwaZulu-Natal would not solve the AAT problem and any potential AW-IPM campaign with a SIT component should include G . brevipalpis [9]. …”

Improving the Diet for the Rearing of Glossina brevipalpis Newstead and Glossina austeni Newstead: Blood Source and Collection – Processing – Feeding Procedures

“…Ever since the successful and sustainable eradication of a Glossina pallidipes Austen population from Zululand in the 1950’s, the two remaining tsetse species Glossina brevipalpis Newstead and Glossina austeni Newstead have always been considered of minor epidemiological importance [3–7]. The outbreak of nagana in 1990 showed that this assumption was a fallacy [8]. …”