Epidemiological investigations on Trypanosoma evansi infection in dromedary camels in the South of Algeria

Abstract

An epidemiological study of Trypanosoma evansi ( T. evansi ) infection in dromedaries was conducted in four wilayate (localities) of Southern Algeria: Béchar, El Bayadh, Ouargla, Tamanrasset. Between February 2014 and April 2016, 1056 camels of different ages and both sexes from 84 herds were sampled. The prevalence was determined through parasitological examination (Giemsa stained thin smear, GST), serological tests (CATT/ T. evansi , ELISA/VSG RoTat 1.2, immune trypanolysis), and molecular tests ( T. evansi type A specific RoTat 1.2 PCR and T. evansi type B specific EVAB PCR). The overall prevalence was 2.4 % with GST, 32.4% with CATT/ T. evansi , 23.1% with ELISA/VSG RoTat 1.2, 21.0% with immune trypanolysis (TL), 11.2 % with RoTat 1.2 PCR and 0% with EVAB PCR. El Bayadh was the most affected wilaya with 11.8% positives in GST, 74.9% in CATT/ T. evansi , 70.1% in ELISA/VSG RoTat 1.2 and 62.2% in immune trypanolysis. Only in Béchar, a non-significantly higher prevalence (13.6%) was observed with RoTat1.2 PCR than in El Bayadh (13.0%). We didn't find any evidence of the presence of T. evansi type B in the study area.

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

“…No effect of camel age on T. evansi seropositivity was observed in our study. Our finding agrees with some surveys (Boushaki et al 2019 ; Pathak & Khanna 1995 ; Shah et al 2004 ), but differs from those of other research groups who reported increased seroprevalence with increasing age (Atarhouch et al 2003 ; Bogale et al 2012 ; Dia et al 1997 ; Eshetu, Desta & Amare 2013 ; Gutierrez et al 2000 ; Mirshekar, Yakhchali & Shariati-Sharifi 2017 ; Olani et al 2016 ; Tehseen et al 2015 ). In contrast to the above findings, one study in Ethiopia revealed higher infection rates in younger camels than in older adult camels (Lemecha, Lidetu & Hussein 2008 ).…”

“…In Algeria, T. evansi infection in camels was confirmed for the first time more than a century ago when parasitological examinations discovered that 10% of 282 camels were infected (Sergent & Sergent 1905 ). Outbreaks of trypanosomosis in dromedary herds associated with mortalities and abortions have been documented (Boushaki et al 2019 ). The T. evansi seropositivity rate in our study (49.5%) was higher than previous serological studies conducted in Algeria by Benfodil et al ( 2020 ) and Boushaki et al ( 2019 ), who reported seroprevalence up to 32.4%, and 9.9%, respectively.…”

“…Outbreaks of trypanosomosis in dromedary herds associated with mortalities and abortions have been documented (Boushaki et al 2019 ). The T. evansi seropositivity rate in our study (49.5%) was higher than previous serological studies conducted in Algeria by Benfodil et al ( 2020 ) and Boushaki et al ( 2019 ), who reported seroprevalence up to 32.4%, and 9.9%, respectively. The higher seroprevalence in the present study could be because of the differences in the topography of the study areas, age of tested animals, proportion of males versus females, sample size, environmental conditions during the sampling period, or differences in diagnostic methods.…”

“…Infection with T. brucei evansi (hereafter, T. evansi ) reduces market value of exported animals, decreases milk yield and lessens animal body condition score, resulting in more than $223 million loss to the camel industry (Salah, Robertson & Mohamed 2015 ). In addition to causing the aforementioned losses, T. evansi is the most important cause of infectious abortions in camels in the Middle East and Africa (Boushaki et al 2019 ; More et al 2017 ). Camels with clinical disease can present progressive emaciation, severe anaemia, reproductive problems (because of infertility, abortions and stillbirths), and eventually death (Desquesnes et al 2013 ).…”

“…In Algeria, T. evansi was first detected in 1903 in infected camels (Sergent & Sergent 1905 ). Since that time, few studies have been performed on livestock, and most were conducted in a limited geographical area with a limited number of samples (Benfodil et al 2020 ; Bennoune et al 2013 ; Boushaki et al 2019 ); those studies concluded only that the hemoparasite can be detected in blood samples. Limited data are available currently concerning the epidemiology and distribution of the T. evansi parasite in Algeria.…”