Symptoms of Canine Leishmaniosis in Tunisian Dogs

Canine leishmaniosis (CanL) is a fatal disease caused by Leishmania infantum which is a zoonotic protozoan transmitted to humans from dogs through sandflies. In Tunisia, there is a lack of knowledge on CanL risk and protective factors that limits the possibilities to design control strategies. In this study, 269 dogs suffering from CanL that were presented by their owners to the clinic of the National School of Veterinary Medicine of Sidi Thabet (Tunisia), were examined. Male dogs were more infected than female dogs (sex-ratio = 1.53). The age distribution in dogs has a normal distribution; mostly animals less than 4 years old (48.7%) gets affected by this disease. The majority of the animals were German Shepherded (14.4%) followed by Staffordshire (12.6%) and Rottweiler (9.6%). Most of the dogs live outdoor (87%), did not receive any acaricidal treatment (88.5%) and were not dewormed (70.3%). Poor body condition (73.2%), depilation (69.1%), lymph node enlargement (67.3%) and lethargy (60.2%) were the most frequent symptoms. Further studies need to be carried out to establish the presence of a relation between the zymodems and the clinical typology of CanL. It is also important to know if these disparities were due to differences in the canine population under study, to inherent differences in susceptibility to the disease or to a genetic diversity of the parasite.

First Molecular Identification and Genetic Characterization of Theileria lestoquardi in Sheep of the Maghreb Region

Theileria lestoquardi is the most prominent Theileria species in small ruminants that causes malignant theileriosis of sheep in Africa and Asia. In the present survey, blood samples and ticks were collected in Kebili (southern Tunisia) from 166 Queue Fine de l'Ouest sheep. Giemsa-stained blood smears, immunofluorescent antibody test (IFAT) and PCR were performed. The DNA was extracted from blood and analysed by PCR targeting 18S rRNA gene of Theileria spp. and then sequenced. A total number of 140 ticks were collected from a total number of 166 sheep during the four seasons. The ticks belonged to two genera and 4 species; the most frequent tick was Hyalomma excavatum 84.3% (118/140) and then Rhipicephalus spp. 15.7% (22/140). Only two animals had positive Giemsa-stained blood smears, and they were also positive by IFAT. The amplicons had 99.3 and 99.6% homology with the BLAST published T. lestoquardi amplicons. To our knowledge, this is the first report of T. lestoquardi in small ruminants within the Maghreb region.

[Prevalence of Toxoplasma gondii infection in Tunisian sheep]

The aim of this study is to estimate the prevalence of Toxoplasma gondii infection in 527 sheep from 4 governorates of Tunisia by Elisa (350 animals) and PCR (177 animals). The seroprevalence in sheep was estimated to be 1.8% (N = 166) in the governorate of Siliana (North Tunisia) and 19% (N = 184) in the governorate of Kasserine (Central Tunisia) with a commercial Elisa kit. T. gondii DNA was extracted from the apex of the heart in 25.5% (N = 106) of sheep from the Sidi-Bouzid governorate (Central Tunisia) and 12.7% (N = 71) from the Ben-Arous governorate (North Tunisia). There was no statistically significant difference between different age categories' prevalence within each locality. Our results indicate that T. gondii infection is frequent in Tunisian sheep. The implementation of a national control programme against toxoplasmosis should not neglect sheep as a frequently infected intermediate host.

Infestation of tracer lambs by Fasciola hepatica in Tunisia: determining periods for strategic anthelmintic treatments

Ovine fasciolosis causes high morbidity and mortality rates, resulting in large economic losses to the sheep industry in northern Tunisia. The authors surveyed ovine fasciolosis (Fasciola hepatica infestation) in a Barbarine sheep flock in the humid region of Tunisia (Sejnane, Governorate of Bizerte) over two consecutive years, 2004 to 2005. To assess the dynamics of fluke infestation, a total of 36 tracer lambs were introduced into the flock successively, in groups of three, every two months, and their infestations were monitored by coproscopy and necropsy. Coproscopic analysis revealed high mean percentages of infestation of 60% and 65% for flock lambs and ewes, respectively. Similarly, a high percentage of infestations was recorded in the tracer lambs (more than 70%) post mortem. Significant fluctuations in infestation dynamics were observed in the tracer lambs, and three distinct infestation periods were identified: a period of very low, non-constant infestation risk during the warm period (from July to October); a high-risk period from March to June, and a third period with a variable but constant infestation risk (from November to February). Based on these results, the authors propose strategic flukicide treatments with triclabendazole, aimed at reducing mollusc infestation and subsequent pasture contamination by metacercariae, during two main periods: in September and in February, just before the reactivation of the molluscs from aestivation and hibernation, respectively.

Evaluation of a simple Theileria annulata culture protocol from experimentally infected bovine whole blood

We have evaluated a new simple technique using whole blood from experimentally infected cattle for the isolation and cultivation of Theileria annulata. The study was carried out on 20 Holstein-Frisian bovines that had been experimentally infected with a virulent lethal dose of Theileria annulata. This technique has been compared to the classical peripheral blood monocyte isolation with Ficoll carried out on 22 experimentally infected Holstein-Friesian calves. The effectiveness of the reference technique was estimated to 86.4%, whilst the effectiveness of the new technique was 100%. Moreover, this new technique leads to time and money saving estimated to € 3.06 per sample. It decreases the contamination risks by reducing the steps of sample manipulation.

[Epidemiological, clinical and parasitological data about canine leishmaniasis in Tunisia]

Epidemiological, clinical and parasitological data concerning canine leishmaniasis were collected in two Tunisian populations of dogs, different in breed and life style: 23 rural dogs and 26 dogs of European breeds. All were symptomatic and lived in the north of Tunisia where human visceral and cutaneous leishmaniasis caused by Leishmania infantum are endemic. Leishmaniasis has been confirmed in all dogs by serology or/and by parasitic identification. Significant differences concerning age and symptoms suggest a higher susceptibility to infection in European imported breeds. In fact individuals of this population were significantly younger; 81% were less than 5 years old whereas 57% of the autochthonous rural dogs were more than 5 years old with 31% of them being older than 9 (p = 0.014). In spite of their young age, 75% of imported breeds presented an affection of their general state with more frequent cutaneous symptoms than the rural dogs (96% versus 69%, p = 0.02). Isoenzyme typing of 31 strains, obtained from the two populations, from different sites (blood, lymph nodes, spleen) has only identified the zymodeme Leishmania infantum MON-1. This stresses the need of more investigations to determine reservoirs of the other enzymatic variants identified in humans in Tunisia and Mediterranean basin.

Detection of natural infections with Theileria annulata on calves at first theileriosis season: comparison of the Indirect Fluorescent Antibody Test (IFAT) and blood smears

The Indirect Fluorescent Antibody Test (IFAT) remains so far the most commonly used test for sero-epidemiological investigations on tropical theileriosis (infection of cattle with Theileria annulata). The present studies evaluated the ability of both IFAT with schizont antigen (schizont IFAT) and blood smears to detect infected animals just after the theileriosis season. This evaluation was performed on a group of 89 calves of known infection status for T. annulata at first disease season, from farms with endemic stability for tropical theileriosis. An additional retrospective group of 84 cattle free of infection was also used for the estimation of the specificity of the schizont IFAT. The sensitivity and the specificity of schizont IFAT were 88.9% (64/72) and 97% (98/101), respectively. Blood smears showed a lower sensitivity of 63.9% (46/72). The agreement between the two detection techniques and the infection status of the animals, evaluated by the Kappa coefficient, was 0.85 and 0.64 for IFAT and blood smears, respectively.

Piroplasmids of livestock in Tunisia

Several species of piroplasms of livestock are present in Tunisia; some of them are of high veterinary importance. This paper reviews the species already reported in Tunisia on the basis of clinical observations, parasitological routine diagnostic and serological surveys, as well as those considered as potentially present according to epidemiological argumentations. The genus Theileria includes four species reported in Tunisia: T. annulata, T. buffeli, T. ovis, and T. equi. The ovine malignant theileriosis agent, T. lestoquardi, appears to be absent in Tunisia. Five species belonging to the genus Babesia were reported in the country, namely B. hovis, B. bigemina, B. divergens, B. caballi, and B. ovis. Furthermore, two more species, B. major and B. motasi, are potentially present in zones where their vectors of the genus Haemaphysalis occur.

Distribution and ecology of ticks (Acari: Ixodidae) infesting livestock in Tunisia: an overview of eighth years field collections

Ticks (Ixodidae) play a significant role as vectors of pathogens of domestic animals in Tunisia. The major losses caused by ticks are related to transmission of protozoan parasites. These include agents of tropical theileriosis and babesiosis in ruminants. Since 1991, we conducted research studies on tick population of livestock in Tunisia. This overview reports a synthesis on tick distribution, their biology and their role as vectors of pathogens in domestic animals, particularly cattle. During the whole period of the study about 15,000 tick specimens were collected from different zones of the country. A total of 14 species were identified. Hyalomma detritum detritum was the most abundant and important (vector of Theileria annulata) species infesting cattle. Hyalomma dromedarii and Hyalomma impeltatum were collected on domestic ruminants in the arid and desertic zones. Hyalomma marginatum marginatum and Hyalomma anatolicum excavatum were widespread and found on livestock hosts. Ixodes ricinus, vector of Babesia divergens and Borrelia burgdorferi sl, colonises mainly the humid zone. Boophilus annulatus and Rhipicephalus bursa infesting cattle, sheep and goats were found in the sub-humid and semi-arid zones. Haemaphysalis sulcata and Hae. punctata were collected in humid and sub-humid zones on cattle and sheep. Rhipicephalus turanicus were collected in different regions, on different animal species. Rhipicephalus sanguineus, tick of dogs, were often collected on livestock. Only few specimens of Hyalomma marginatum rufipes and Hyalomma franchinii were collected.

Tropical theileriosis in Tunisia: epidemiology and control

In Tunisia, tropical theileriosis (Theileria annulata infection of cattle) is one of the major diseases affecting cattle in the summer. Each year about 2,500 clinical cases are recorded in the country, mainly in pure-bred animals. An attempt was made in the North of Tunisia to estimate the direct cost related to clinical cases of TT. In the endemic regions, three states of endemicity were described according to cattle age categories at highest disease risk: (i) endemic stability, (ii) low endemic instability, (iii) high endemic instability. The characterisation of these endemic situations, which are conditioned by the levels of the vector tick population and the quantitative aspects of the infection in ticks, are highly relevant for the development of a live attenuated cell line vaccine against TT targeting the cattle population at disease risk in Tunisia. A research programme was set up to develop the attenuation of four local parasite stocks. Two cell lines infected with two distinct T. annulata stocks were tested in the field on pure-bred animals of different age groups from regions with high disease incidence. The vaccination with each of the two cell lines showed a high efficacy. However significant differences in vaccine reactions rates were observed between the two attenuated cell lines emphasising the importance of achieving an optimal balance between protection and vaccine tolerance particularly in pure-bred lactating cows.

Innate and adaptive immune responses co-operate to protect cattle against Theileria annulata

For many years it was assumed that Theileria annulata resembled T. parva, parasitizing lymphocytes and causing lymphoproliferative disease, with the two species being controlled by similar protective immune responses. Patricia Preston et al. here review the evidence that has led to a different view of T. annulata. It is now thought that the schizonts of T. annulata inhabit macrophages and B cells, and that tropical theileriosis is not a lymphoproliferative disease. Both innate and adaptive responses contribute to recovery from infection and resistance to challenge and cytokines produced by infected and uninfected cells influence the outcome of infection. Partial protection has been stimulated recently by defined recombinant antigens; efficacy depended upon the delivery system.

Cattle infestation by Hyalomma ticks and prevalence of Theileria in H. detritum species in Tunisia

Seventy-four cattle, from three farms endemic for tropical theileriosis in the north of Tunisia, were studied for tick populations from June 1991 to June 1992. Ticks were removed from cattle twice a month in the summer and every month the rest of the year. They were identified and assessed for Theileria infection. A total of 5083 Hyalomma adult ticks were collected and the major species found was H. detritum (84.3%). The activity of this species is limited between June and August with a peak in numbers observed at the end of June and the beginning of July. Amongst the 2356 Hyalomma ticks dissected, no evidence of salivary gland infection was found in either H. m. marginatum or H. a. excavatum. However, 12.4% (277/2230) of H. d. detritum dissected ticks were infected with Theileria species and amongst these, 62% had one to two sporoblasts in their salivary glands (range 1-91). The prevalence, but not the intensity, of infection was greater in females than in male ticks, and the cases of tropical theileriosis followed the peak of infected females. This suggests that female ticks have a more important role in theileriosis transmission than male ticks. A significantly lower number of adult H. detritum were collected from calves, at their first tick season, than from adult cattle. Finally, this study showed that the infestation level of cattle by H. d. detritum and the prevalence of Theileria-infection in these cattle varied between the three farms studied.

A preliminary study on the attenuation of Tunisian schizont-infected cell lines of Theileria annulata

Four Theileria annulata cell lines were characterised at low passage levels using two polymorphic markers and then used to infect calves. Their virulence seemed to be related to the number of genotypes present within the cell line. In all, 3 of the 4 cell lines were cultured up to passage 100 or 200 and inoculated into calves. Their characterisation using the same markers indicated that the attenuation was related to a reduction in the parasite polymorphism down to a single genotype. The immunogenicity of the three attenuated cell lines was assessed in calves using two types of challenge. Optimal protection was observed against homologous challenges. The level of immunity to heterologous challenges appeared to decrease with attenuation and seemed to depend on the cell line used.

First report of Babesia divergens in Tunisia

Babesia divergens of bovine origin was isolated, for the first time in Tunisia, from a cow of a local breed (Bos taurus) from a locality in the north-west of the country. Gerbils (Meriones unguiculatus) were used for the isolation of the parasite which was inoculated into a splenectomised Friesian calf that developed a babesiosis, thus confirming the presence of the parasite.