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

Abstract

A cross-sectional survey was carried out in four counties of Jonglei State, South Sudan, between May and June 2012 to determine the distribution and northern limit of Theileria parva, the causative agent of East Coast fever in cattle, and its tick vector Rhipicephalus appendiculatus, as a prerequisite to the deployment of relevant control strategies. A total of 1636 ticks, 386 serum samples and 399 blood samples were collected from indigenous, apparently healthy, cattle of different age groups. Tick species were identified morphologically, and the identity of R. appendiculatus was confirmed by DNA barcoding. Overall, the T. parva infection rate in R. appendiculatus was 25% as shown by nested PCR. ELISA was used to assess antibodies to T. parva, and the overall seroprevalence was 22.8%. PCR of the blood samples showed 55 (13.8%) were positive for T. parva. This is the first molecular confirmation of T. parva DNA in areas north of Juba, where it was previously known and established. The northern limit of T. parva was determined as N⁰06.17.792, about 242 Km north from Juba. Implication of this limit on the epidemiology and control of ECF is discussed.

The Rhipicephalus appendiculatus tick vector of Theileria parva is absent from cape buffalo (Syncerus caffer) populations and associated ecosystems in northern Uganda

“…Among 100 Ankole cattle from farms directly adjacent to LMNP, 56% were positive by p104 PCR. Further north in the Sudan, T. parva has been observed to be endemic in cattle, and the presence of the parasite and the vector in this country is thought to be at least partially mediated by extensive anthropogenic movement of livestock (Malak et al 2012;Marcellino et al 2015;Salih et al 2007). In this context, it will be important to examine the T. parva infection status of cape buffalo in South Sudan, since ITM vaccination may in future be deployed in this region, and it is possible that buffalo-derived T. parva could breakthrough immunity induced in cattle as observed in Kenya.…”

Towards wider and more efficient deployment of live vaccines for control of Theileria parva and Theileria annulata infections in cattle in eastern, central and northern Africa

“…Theileria parva causes East Coast fever (ECF), an economically important disease of cattle in 15 countries in eastern, southern and central Africa where it is the major source of cattle mortality in the low resource livestock agroecosytems (Thumbi et al., ). There are recent reports of geographical spread of T. parva at the borders of the existing distribution and over substantial geographical distances (Marcellino et al., , Silatsa et al. in this issue).…”

Role of climate and other factors in determining the dynamics of tick and tick-transmitted pathogen populations and distribution in western, central and eastern Africa.

“…Extensive anthropogenically mediated movement of cattle is known to occur between Northern Uganda and South Sudan and, as a consequence, both R. appendiculatus and T. parva have been detected over extensive regions of South Sudan ( Salih et al ., 2018 ;Marcellino et al ., 2012Marcellino et al ., , 2017. As a result, East Coast fever is an emerging problem in that country and the long-term impact may be considerable.…”