Seroprevalence and risk factors for Trypanosoma evansi, the causative agent of surra, in the dromedary camel (Camelus dromedarius) population in Southeastern Algeria

Abstract

Surra, caused by Trypanosoma evansi , is a re-emerging animal trypanosomosis, which is of special concern for camel-rearing regions of Africa and Asia. Surra decreases milk yield, lessens animal body condition score and reduces market value of exported animals resulting in substantial economic losses. A cross-sectional seroprevalence study of dromedary camels was conducted in Algeria, and major risk factors associated with infection were identified by collecting data on animal characteristics and herd management practices. The seroprevalence of T. evansi infection was determined in sera of 865 camels from 82 herds located in eastern Algeria using an antibody test (card agglutination test for Trypanosomiasis – CATT/ T. evansi ). Individual and herd seroprevalence were 49.5% and 73.2%, respectively, indicating substantial exposure of camels to T. evansi in the four districts studied. Five significant risk factors for T. evansi hemoparasite infection were identified: geographical area, herd size, husbandry system, accessibility to natural water sources and type of watering. There was no association between breed, sex or age with T. evansi infection. Results of this study provide baseline information that will be useful for launching control programmes in the region and potentially elsewhere.

Serological survey and associated risk factors' analysis of Trypanosomiasis in camels from Southern Tunisia

“…At the herd level, the overall seroprevalence rate of T. evansi infection was high (64.9%) in our study which revealed the wide spread of surra in the south of Tunisia which could be related to vector abundance in the study area. The result obtained by Benaissa et al was different from our finding indicating high seroprevalence rates of surra in camels in Algeria at the herd level ( Benaissa et al, 2020 ). The governorate of kebili has the high seroprevalence rate of T.evansi infection at the herd level.…”

“…The seroprevalence of T. evansi varied significantly among governorates, and the governorate of Kebili seems to be the most affected with an infection rate of 37.5%. The high density of dromedaries and the presence of cross-border herd movement with Algeria could explain the high seroprevalence in this governorate ( Benaissa et al, 2020 ; Bouslikhane, 2015 ). Indeed, it was demonstrated that the seroprevalence of T.evansi in southern Algeria, an area bordering the governorate of Kebili, was assessed at 45% ( Benaissa et al, 2020 ).…”

“…The high density of dromedaries and the presence of cross-border herd movement with Algeria could explain the high seroprevalence in this governorate ( Benaissa et al, 2020 ; Bouslikhane, 2015 ). Indeed, it was demonstrated that the seroprevalence of T.evansi in southern Algeria, an area bordering the governorate of Kebili, was assessed at 45% ( Benaissa et al, 2020 ). Moreover, the presence of an important number of watering points ( Centre national de veille zoosanitaire 2017 ), wetlands, and saline lakes in Kebili in comparison to the other governorates, is likely to enhance the spread of trypanosomiasis, through the development and proliferation of tabanids, implicated vectors in the transmission of T. evansi ( Abera et al, 2015 ; Ben , 2019 ; Rafu et al, 2021 ) .…”

“…Trypanosomiasis in human was known as “the sleeping sickness”, caused by Trypanosoma brucei . However, for the veterinary concern, many species and subspecies of Trypanosoma ( T. congolense, T. vivax, T. brucei brucei and T. brucei evansi ) can affect hosts like domestic livestock ( Benaissa et al, 2020 ; Giordani et al, 2016 ). Of these species, Trypanosoma evansi , agent of “surra”, has the widest host range and geographical distribution.…”

“…T. evansi is widespread, and high seroprevalence was in Somalia (68,7%), Sudan (52,2%), and Southeastern Algeria (49,5%) ( Babeker and Hassab Elrasoul, 2014 ; Benaissa et al, 2020 ; Kadle et al, 2019 ), with a signaled presence in all African countries, and a continued spreading to the Middle East and South-East Asia ( Desquesnes et al, 2013 ). In Tunisia, despite the large population of camels and the reported outbreaks of trypanosomiasis, the disease is poorly documented and is underestimated.…”