Infection of the equine population by Leishmania parasites

Infection of equids by Leishmania (L.) parasites was previously described in both the Old and New World, particularly in Central and South America. Equine cutaneous leishmaniasis (CL) is caused by the Leishmania species, L. Viannia (V.) braziliensis and L. infantum, previously identified in humans and other parasite hosts living in the same geographic endemic areas. Sporadic autochthonous clinical cases, with no travel history, were documented in several countries including Germany, Portugal, Spain, Texas and Brazil; L. infantum and L. (Mundinia) martiniquensis were the infectious species. Prevalence of subclinical infections is extremely low and CL is observed in only a small proportion of infected animals with the appearance of single or multiple cutaneous lesions located on the head, external ear, scrotum, legs and the neck. To date, there has been no report of visceral abnormalities. However, the mild clinical profile of the disease and its spontaneous regression may indicate that skin lesions related to Leishmania infection is underdiagnosed. Importantly, although the prevalence of Leishmania infections in the equine population is low, a risk may rise from its potential involvement in the parasite transmission cycles as a source of infection for phlebotomine vectors and susceptible mammalian hosts. This review article summarises our current knowledge of the epidemiology, clinical presentation and diagnosis of Leishmania-infected equids.

Evidence of natural infections with Trypanosoma, Anaplasma and Babesia spp. in military livestock from Tunisia

Livestock constitute habitual hosts and carriers for several infectious pathogens which may represent a serious public health concern affecting the readiness of military forces and lead to wide economic losses. The present report aimed to investigate the prevalence of some haemopathogens infecting military livestock, particularly, dromedaries, sheep and horses using Giemsa-stained blood smears. A total of 300 animals (100 from each species) were selected, clinically examined and sampled. Trypanosoma spp. (22.0%), Anaplasma spp. (17.0%) and Babesia spp. (1.0%) were identified in camels' blood. Six dromedaries were found to be co-infected by Trypanosoma and Anaplasma organisms (6.0%). Camels of female gender, infested by ticks and showing clinical signs were statistically more infected by Trypanosoma spp., compared to those of male gender, free of ticks and apparently healthy (P= 0.027, 0.000 and 0.004, respectively). Babesia spp. infection (1.0%) was identified, for the first time in Tunisia, in one adult female camel that presented abortion and anemia. Anaplasma spp. was the only haemopathogen identified in examined sheep (6.0%) and horses (17.0%). Horses infested by Hippobosca equina flies and sheep infested by Rhipicephalus turanicus ticks were more infected by Anaplasma spp. than other non-infested animals (P=0.046 and 0.042, respectively). Hyalomma dromedarii, H. impeltatum and H. excavatum were the most prevalent diagnosed ticks removed from camels with an intensity of infestation of 1.2 ticks per animal. However, in sheep, only R. turanicus was identified. H. equina and Tabanus spp. were the potential hematophagous flies found in dromedaries and horses herds. This useful data must be taken into consideration during animal treatment and vectors' control programs in Tunisian military farms which help to limit the diffusion of vector-borne diseases, keep our livestock healthy and reduce economic losses.

Interaction between canine and human visceral leishmaniases in a holoendemic focus of Central Tunisia

Canine visceral leishmaniasis (CVL) is endemic in the Mediterranean basin. In Tunisia, CVL is spatially associated with human visceral leishmaniasis (HVL) affecting mostly children younger than 5 years old. In this study, seroprevalence of Leishmania infantum infection in dogs was assessed in highly endemic districts of the governorate of Kairouan where more than 50% of HVL cases in Tunisia were reported. An entomological investigation was also carried out in two endemic districts (Bouhajla and Haffouz) to assess sand fly fauna and infection status of sand flies with Leishmania. A total of 191 serum samples were collected from healthy dogs and tested for anti-L. infantum antibodies by indirect immunofluorescence antibody test (IFAT). Overall seroprevalence for L. infantum was 26.7% being highest among dogs in the district of Bouhajla (52.7%) and the lowest in the district of Chbika (5.2%). In dogs, seroprevalence did not differ significantly based on gender or age, with dogs younger than 1 year showing a higher seroprevalence compared to older dogs. These findings suggest strong force of infection in naïve animals in holoendemic regions leading to emerging high incidence of HVL. Concomitant to the high CVL prevalence observed in the Bouhajla district, a significantly high cumulative HVL incidence also was observed in this district. Phlebotomus perniciosus and Phlebotomus longicuspis were the most abundant sand fly species in Bouhajla and Haffouz districts. The rate of Leishmania-DNA infection in sand flies was 9.4%. This finding points to spatial correlation between the occurrence of disease in humans, a high rate of infection in dogs and a high abundance of P. pernicious and P. longicuspis. Thus, CVL is the main risk factor for transmission to humans and subsequently, it is an important parameter for controlling transmission to humans.