Current status of tropical theileriosis in Northern Africa: A review of recent epidemiological investigations and implications for control

Abstract

Tropical theileriosis caused by the apicomplexan hemoparasite Theileria annulata is a tick‐borne disease that constraints livestock production in parts of Europe, Asia and Africa. Four Hyalomma tick species transmit T. annulata in at least eight Africa countries (Mauritania, Morocco, Algeria, Tunisia, Egypt, Sudan, South Sudan and Ethiopia). The two dominant T. annulata vector ticks present in Africa, H. scupense and H. anatolicum, underlie two different patterns of transmission, which in turn greatly influence the epidemiology of tropical theileriosis. H. dromedarii and H. lusitanicum are also capable of transmitting T. annulata in North Africa, but their roles are associated with specific production systems and agro‐ecological contexts. The emergence of resistance to the most widely used theilericidal compound, buparvaquone, continues to limit the effectiveness of chemotherapy. In addition, acaricide use is increasingly becoming unsustainable. Deployable T. annulata attenuated live vaccines established from local strains in Tunisia, Sudan and Egypt are available, and recent work has indicated that these vaccines can be protective under conditions of natural transmission. However, vaccination programmes may vary over space and time due to differences in the prevalence of disease amongst cattle populations, as well seasonal variation in vector activity. We review recent descriptive and analytical surveys on the epidemiology of T. annulata infection with reference to (a) demographic aspects such as breeds and ages of cattle herds previously exposed to distinct T. annulata infection pressures and (b) seasonal dynamics of tick activity and disease transmission. We then discuss how the wider endemic patterns that we delineate can underpin the development and execution of future vaccination programmes. We also outline options for integrated control measures targeting tick vectors and husbandry practices.

Knowledge and perception on ticks and tick-borne diseases among veterinary medicine students from the North African countries of Algeria, Egypt, and Tunisia

“… From contact with infested animals From soil during grazing From infested barns ( Estrada-Peña and de la Fuente, 2014 ) What is (are) the pathogenic role of ticks? Blood spoliation/Anaemia Pathogens transmission Skin lesions and irritation ( Jongejan and Uilenberg, 1994 ) What is (are) the name(s) of tick-borne disease(s) in your country Anaplasmosis, Babesiosis, Theileriosis ( Ben Said et al, 2018 ; Gharbi et al, 2020 ; Schnittger et al, 2012 ) On which period of the year, these tick-borne diseases are transmitted in your country? Depends on the pathogen species and the region ( Walker et al, 2003 ) Do ticks transmit zoonotic agents to humans?…”

First Report of Theileria Annulata in Nigeria: Findings from Cattle Ticks in Zamfara and Sokoto States

“…This study provides the rst report of T. annulata in Nigeria. Tropical theileriosis is recognised as one of the most economically important diseases of livestock across North Africa and much of Asia [67], and its presence in SSA, where livestock productivity is already severely compromised by endemic parasites and pathogens [3], is an additional concern. In Africa, T. annulata has so far been detected in eight countries, mostly in the northern (i.e.…”

“…Importantly, the emergence and spreading of resistance to the most widely used theilericidal compound on the market (i.e. buparvaquone) in T. annulata strains circulating in Northern and Eastern Africa [67], further highlights the need for future epidemiological investigations. Moreover, given that the susceptibility of camels to T. annulata has been established and infections appear common elsewhere [76], they too should be surveyed to explore what role they play in the natural cycle of T. annulata in the area.…”

Bovine piroplasmosis‐anaplasmosis and clinical signs of tropical theileriosis in the plains of Djurdjura (north Algeria)

“…This study was carried out between 2004 and 2008, during tick activity period, from May to September (Gharbi et al, 2020). Moreover, anaplasmosis is also transmitted mechanically by haematophagous vectors (Tabanus, Stomoxys…).…”