Epidemiological perspectives of ticks and tick-borne diseases in South Sudan: Cross-sectional survey results

Abstract

A cross-sectional study was conducted between September and October 2010 in five states of South Sudan that were selected on the basis of the perceived risk of tick-borne diseases. The purpose was to investigate epidemiological parameters of tick-borne diseases in South Sudan and their uses in future control strategies. A total of 805 calves were assessed by clinical, microscopic and serological examination and tick counts. The indirect Enzyme-Linked Immuno-Sorbent Assay (ELISA) was used to detect antibodies to Theileria parva, Theileria mutans, Anaplasma marginale and Babesian bigemina. Sero-conversion risks for T. parva and T. mutans were 27.3% and 31.3% respectively, whilst the risk was 57.6% and 52.8% for A. marginale and B. bigemina, respectively. Major tick species identified include Rhipicephalus appendiculatus, Rhipicephalus decoloratus, Rhipicephalus microplus, Amblyomma variegatum, and Rhipicephalus evertsi. There was great variation (P ≤ 0.001) in the number of all these ticks, both between herds in a state and between calves in an individual herd. The low and intermediate sero-conversion risks observed in the study states suggest that immunisation against East Coast fever (ECF) is justified. Fortunately, three major genotypes that were identified by applying Polymerase Chain Reaction Restriction Fragment Length Polymorphism (PCRRFLP) analysis on the p104 to the blood samples and T. parva Muguga, matched very well with T. parva Kiambu 5 and T. parva Muguga; therefore the Muguga cocktail can be used for the immunisation of cattle in South Sudan. However, prospective studies are required to develop optimal control measures for tick-borne diseases under different ecological and husbandry practices in South Sudan.

The Emergence of Theileria parva in Jonglei State, South Sudan: Confirmation Using Molecular and Serological Diagnostic Tools

“…Our study extends on the data of Kivaria et al. () and demonstrates that T. parva and the R. appendiculatus tick vector are present in Jonglei State. Our data indicate that R. appendiculatus is confined to the southern part of Bor County, since it was not found north of Wancuei, nor was it found in the other counties of Twic East, Duk or Uroro.…”

“…A number of studies have shown that ECF has become established in South Sudan and that it is an emerging disease with considerable risk of it spreading to many parts of the country (Julla, ; Salih et al., , ,b; Kivaria et al., ; Malak et al., ; Marcellino et al., ; Nyoap et al., ). For a country that has been rife with war and insecurity for many decades, the wide‐scale establishment of this disease could lead to further hardship for the local communities, most of whom rely on cattle for their livelihoods.…”

“…Early reports suggested that ECF and its tick vector, R. appendiculatus, were confined to the states of Eastern and Central Equatoria (Morzaria et al., ; Julla, ). However, more recent reports indicate that since the signing of the Comprehensive Peace Agreement (CPA) in 2005, and subsequent movement of people and their livestock, ECF is now an emerging disease in South Sudan, where it is having a devastating impact on cattle productivity (Marcellino et al., ; Kivaria et al., ; Nyoap et al., ). There are now reports of ECF spreading to more northern areas that were previously free of the disease, including a recent outbreak in Warrap State (A. Dut, unpublished data), and reports of ECF spreading to Jonglei and Upper Nile (Kivaria et al., ; Nyoap et al., ).…”

Abundance and distribution of Ixodid tick species infesting cattle reared under traditional farming systems in Tanzania

“…Another reason can be attributed to progressive selective grooming of the calves' head, ears and neck from their respective dams (Fivaz and Waal, 1993). Additionally, in all the three regions investigated, young animals were grazed in areas close to the farmhouse while adult animals were grazed in grasslands and bushy areas located far away from the homestead as was the case in South Sudan (Kivaria et al, 2012), therefore reducing the risk of exposure of young stock to tick infestation. Adult animals continue to be at high risk of infestation with ticks due to prolonged mingling with other animals during grazing and watering since communal grazing lands are used.…”

A three year follow-up study on the occurrence of bovine ehrlichiosis (cowdriosis) at Gondar University dairy farm

“…This may be related to the seasonal occurrence of Amblyomma vectors, reported by a number of different authors (Gebre et al, 2001;Tesema and Gashaw, 2010;Koney et al, 2004;Kivaria et al, 2012;Bekker et al, 2001).The characteristic clinical signs of heartwater, cowdriosis (Radostits et al, 2007) were recorded in this study. The temperature elevation declines as the disease progresses which results in a more unfavourable prognosis.…”