Limam Sassi

Prevalence of piroplasms in small ruminants in North-West Tunisia and the first genetic characterisation of Babesia ovis in Africa

In this study, the prevalence of piroplasms in sheep and goats was assessed with Giemsa-stained blood smear examination, PCR and nested PCR-restriction fragment length polymorphism (RFLP) to identify Babesia and Theileria species, respectively, in 338 small ruminants (172 sheep and 166 goats) from three sites in North-West Tunisia during the 2011 summer season. The overall infection prevalence of piroplasms in Giemsa-stained blood smears was 3.2% (11/338), with a parasitaemia ranging from 0.01 to 0.05%. PCR detected two species, namely Babesia ovis (in sheep and goats) and Theileria ovis (in sheep), with an overall prevalence of 16.3%. The molecular prevalence of B. ovis was significantly higher in sheep than in goats (17.4% and 9%, respectively, p = 0.034). The same trend was observed for T. ovis in sheep and goats (5.8% and 0%, respectively, p = 0.004). Comparison of the partial sequences of the 18S ssu rRNA gene revealed 100% similarity amongst Babesia from sheep and goats. The single Theileria sequence in this study showed 100% similarity to T. ovis. A high similarity with all the blasted genotypes was reported for Theileria and Babesia sequences. This is the first molecular detection of B. ovis and genetic characterisation of small ruminants’ piroplasms in Africa.

Première étude sérologique de la prévalence d’ Anaplasma phagocytophilum chez le dromadaire ( Camelus dromedarius ) en Tunisie

The aim of the study was to evaluate the seroprevalence of Anaplasma phagocytophilum in dromedary (Camelus dromedarius). Sera of 226 healthy dromedaries from three regions of Tunisia (Sidi Bouzid, Bouficha and Douz) were tested by indirect immunofluorescence (IFA). The overall infection rate was estimated at 29.2%. The study of risk factors showed that region, age, gender, presence of ticks and types of breeding had no influence on the seroprevalence of A. phagocytophilum. This study indicates for the first time in Tunisia that dromedary may be involved in the natural cycle of A. phagocytophilum.

Population dynamics of ticks infesting the one-humped camel (Camelus dromedarius) in central Tunisia.

A tick population was monitored on 30 camels (Camelus dromedarius) over one year in Kairouan region, Central Tunisia. A total of 1630 ticks was collected and identified resulting in an estimate of different parasitological indicators. The ticks belonged to 2 genera and 5 species: Hyalomma impeltatum (53%) and Hyalomma dromedarii (45%) were the dominant species followed by Hyalomma excavatum (1%), Hyalomma marginatum (0.5%), and Rhipicephalus turanicus (0.5%) (p<0.001). Mean infestation prevalence was 90.6%; all the animals were infested by at least one tick from May to September. The highest mean prevalence was observed in H. impeltatum (60%), the lowest was reported in R. turanicus (0.03%) (p<0.05). Mean overall intensity of infestation was 4.4 ticks/animal. The highest mean intensity was observed in H. impeltatum (2.7 ticks/animal). Overall mean abundance of ticks was 4.4 ticks/animal. Different abiotic factors, namely monthly mean minimum and monthly mean maximum temperatures and the number of sunny days were positively correlated with overall monthly tick burdens which were in turn negatively correlated with the monthly mean relative humidity. This is the first study on camel tick dynamics in Tunisia.

Hyalomma scupense (Acari, Ixodidae) in northeast Tunisia: seasonal population dynamics of nymphs and adults on field cattle

Hyalomma scupense is a two-host tick infesting mainly cattle representing in North Africa the vector of tropical theileriosis (Theileria annulata infection), a major tick-borne disease affecting cattle. Any effective control programme of ticks requires a good knowledge of the biology of the target species. In the present study, three cattle farms in northeast Tunisia were surveyed during the activity seasons for adult and nymphs of Hyalomma scupense. Several indicators were studied, including chronological indicators, infestation prevalence, infestation intensity and feeding predilection sites of the ticks. The adult ticks were present from mid-June to late November. Nymphs were observed on animals from early September to late November. A large proportion of the ticks were attached in the posterior udder quarters: 41% and 64% of adult ticks and nymphs, respectively. The animals that were heavily infested by adult ticks were also heavily infested by nymphs. Moreover, 17% of adult ticks and 53% of nymphs were present on only 5% of cattle population. These data are important for the success of targeted acaricide application leading to a dramatic decrease of acaricide quantity needed for the treatment. When the preferential sites of attachment are known, the effectiveness of manual removal of ticks can be improved. The presence of highly infested animals is to be considered when any control programme is implemented, since these animals harbour a high proportion of the ticks.

Molecular prevalence of Toxoplasma gondii DNA in goats’ milk and seroprevalence in Northwest Tunisia

Abstract Toxoplasmosis is a worldwide zoonosis with high impact on human and animal health. Consumption of unpasteurized milk is a risk factor of human toxoplasmosis. The aim of this study was to estimate the seroprevalence and molecular prevalence of T. gondii in goats’ milk in Northwest of Tunisia (Jendouba Governorate). A total number of 77 blood samples were collected from six herds were screened with a commercial ELISA kit for T. gondii antibodies. For the same goats’ samples, a nested PCR was performed to detect T. gondii DNA in milk. The seroprevalence of T. gondii infection was 31.2% (±0.05) while the molecular prevalence of this parasite in milk was estimated to 7.8% (±0.03). A very low value of kappa showed that there is not agreement between seroprevalence and parasite prevalence in milk. These results suggest that the consumption of raw milk from naturally infected goats is a potential source of human infection. An extension programme should be implemented to decrease related to goats’ raw milk consumption.

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.

Molecular and Phylogenetic Study of Bm86 Gene Ortholog from Hyalomma excavatum Tick from Tunisia: Taxonomic and Immunologic Interest

In order to assess the taxonomic and immunologic interest of Bm86 orthologs of Hyalomma ticks, partial sequence of Bm86 gene was amplified and sequenced. The sequences were isolated from three engorged Hyalomma excavatum females (Ariana strain, Tunisia). The analysis of nucleotide sequences showed increasing diversity rates of 0.26, 2.36, 4.97 and 6.02% between analyzed sequences and those isolated from H. excavatum specimen from a laboratory colony (Sousse strain, Tunisia), H. anatolicum, H. marginatum and H. scupense, respectively. The phylogenetic study showed a perfect agreement with recent data of systematic of ticks. This proves that genetic analysis of Bm86 orthologs isolated from Hyalomma ticks could be used to assist morphological diagnosis. In addition, amino-acid sequence comparison showed a high diversity rate (33-34%) between Bm86 and He86-A1/A2/A3 (Ariana strains) which can decrease the effectiveness of vaccination by commercial and experimental vaccines based on Bm86 against H. excavatum. Amino-acid diversity between Hd86-A1 used in an experimental vaccine against H. scupense and He86-A1/A2/A3 (Ariana isolates) was more limited (10.2%), thus suggesting that Hd86-A1 vaccine candidate might be more appropriate to target H. excavatum tick than corresponding Bm86 vaccines.

Première étude sérologique de la prévalence d'Anaplasma phagocytophilum chez le dromadaire (Camelus dromedarius) en Tunisie First serological study of the prevalence of Anaplasma phagocytophilum in dromedary (Camelus dromedarius) in Tunisia

The aim of the study was to evaluate the seroprevalence of Anaplasma phagocytophilum in dromedary (Camelus dromedarius). Sera of 226 healthy dromedaries from three regions of Tunisia (Sidi Bouzid, Bouficha and Douz) were tested by indirect immunofluorescence (IFA). The overall infection rate was estimated at 29.2%. The study of risk factors showed that region, age, gender, presence of ticks and types of breeding had no influence on the seroprevalence of A. phagocytophilum. This study indicates for the first time in Tunisia that dromedary may be involved in the natural cycle of A. phagocytophilum.