An investigation on vertical transmission of Leishmania infantum in experimentally infected dogs and assessment of offspring's infectiousness potential by xenodiagnosis.

Dogs are the main reservoir host of Leishmania infantum, etiologic agent of human visceral leishmaniasis (HVL) and canine visceral leishmaniasis (CVL). Transmission of L. infantum to humans and dogs is mainly through the bite of infected sand flies. In the Western Mediterranean basin, Phlebotomus perniciosus is the main vector of L. infantum. However, occasional vertical transmission of L. infantum has been reported. This study investigated L. infantum vertical transmission in offspring of experimentally infected dogs. Among 14 surviving puppies from three female beagle dogs that developed CVL following an experimental infection with L. infantum, one was tested positive by indirect immunofluorescence antibody test, by PCR and by xenodiagnosis with a high parasite burden in the spleen at 14 months old. None of the remaining puppies were tested positive for L. infantum. These findings strongly suggest that infected puppies following vertical transmission can sustain infection and contribute in infecting sand flies with L. infantum. Any strategy for controlling CVL should take into consideration the vertical transmission of L. infantum.

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.

[Cultures on NNN medium for the diagnosis of leishmaniasis]. / Les cultures sur milieu NNN dans le diagnostic biologique des leishmanioses.

Cutaneous and visceral leishmaniasis (VL, CL) represent the most frequent vector-borne diseases in Tunisia. Their biological confirmation is necessary before the administration of restricting, expensive and toxic specific treatments. Retrospective evaluation of the contribution of Leishmania cultures on NNN medium in leishmaniasis diagnosis have been done using the data of 375 cultures concerning 214 CL cases and 125 VL cases consecutively recruited in Pasteur Institute of Tunisia between 1995 and 2007. The global sensitivity of the culture in the course of CL was of 68.2%. It was significantly higher during zoonotic CL (78.8%) compared to that during sporadic CL (54.9%); p<0.001. This difference is explained by the easier thrust in NNN medium of Leishmania (L.) major, the agent of zoonotic CL than that of L. infantum, particularly its zymodeme MON-24, agent of sporadic CL. In the course of VL, and in spite of the better sensitivity of bone marrow aspirates (BMA) culture (70.8%), the blood buffy-coat, which permit to avoid the trauma induced by BM aspiration gave promising results (58.2%), the difference being not significant. Besides, in the course of both CL and VL, the direct examination of smears is revealed more sensitive, respectively 89.7% and 93.4% (p<0.01 and p<0.01). Although, systematic cultures practise, in parallel with direct examination, is recommended. In fact, in addition of straightening out some diagnosis, 22 cases in our series, the culture provide the isolation and the isoenzymatic identification of the causative species and strains allowing a better comprehend of parasite life cycles and a disposing of important epidemiological data for suitable control measures. As known with all cultures, those of Leishmania are also exposed to the contamination problem, which reached 5.9% in our study. In conformity with previsions, the contamination concerned much more cutaneous samples (8.4%) than blood or BM ones (2.5%; p=0.015).

[Epidemiology of Leishmania (L.) infantum, L. major and L. killicki in Tunisia: results and analysis of the identification of 226 human and canine isolates]. / Epidémiologie de Leishmania (L.) infantum, L. major et L. killicki en Tunisie: résultats et analyse de l'identification de 226 isolats humains et canins et revue de la littérature.

The epidemiological situation of leishmaniasis in Tunisia is characterised by the co-existence in a very limited territory (165,000 km2, Sahara included), of 4 clinical forms: the infantile visceral leishmaniasis (VL) and 3 cutaneous leishmaniasis (CL) forms (sporadic, zoonotic and chronic). In addition to the useful epidemiological data, identification of the causative parasitic species is essential to determine the geographic distribution of each form and to select appropriate therapeutic procedure and suitable control measures. 226 Leishmania isolates, 135 human's coming from 59 VL cases and 76 CL cases and 91 canine's were identified by the isoenzyme electrophoresis reference technique. Results confirm the endemicity of the 4 forms mentioned above. The sporadic CL, confined to the North of the country is principally caused by L. infantum MON-24 (72.2%). VL which has reached the southern ridge in the central area of Tunisia, in the governorate of Kairouan (36 typed isolates), presents an unusual high proportion of L. infantum MON-24. In fact, this zymodeme, rather dermotropic is responsible for 47.2% of the cases vs 13% in the other regions of the country where L. infantum MON-1 remains predominant with 78.3% of typed isolates, the difference being statistically significant (P < 0.01). A third zymodeme, L. infantum MON-80 is sporadically pointed out during VL or in sporadic CL. Despite the high number of canine isolates (n=91) coming from 6 governorates, only the zymodeme L. infantum MON-1 was identified, letting hypothetic the reservoir of the 2 other zymodemes of the species identified in humans. Those absences may be related to cross infections, with a low sensitivity to L. infantum MON-24 leading to a selection of MON-1 at the time of culture passages. Hence it is important to develop molecular tools of direct identification on initial biological samples without going through cultures. Zoonotic CL remains the predominant cutaneous form in the central and southern area of Tunisia. However L. killicki, agent of the chronic CL, is confirming its presence out of its original focus of Tataouine in the southern-east of the country in both zoonotic CL and VL areas.

[Efficacy of Deltamethrine-impregnated collars Scalibor in the prevention of canine leishmaniasis in the area of Tunis]. / Efficacité des colliers Scalibor imprégnés de deltaméthrine dans la prévention de la leishmaniose canine dans la région de Tunis.

The anti-sandflies and, insecticides impregnated collars are actually mentioned as the main mean for prevention and control of Canine leishmaniasis. An evaluation of the Scalibor collar was undertaken in leishmaniasis active sites in Tunis area, (northern Tunisia). Eighty leishmaniasis free dogs (42 collared and 38 as control dogs) were submitted to a serological detection using ELISA technique for anti-Leishmania antibodies before and after transmission season in 2005 and 2006. Seroconversions were detected by ELISA and controlled by indirect immunofluorescence antibodies test. Confirmation of infection in seroconverted dogs was based on the detection of the parasite by culture in NNN medium or detection of parasite's DNA by real time PCR. Among 38 control dogs, 6 (15.8%) were infected by Leishmania infantum during the study period against zero in the collar group; the difference is statistically significant (p=0.02). This result is an additional confirmation of the prophylactic properties of Scalibor protector band against canine leishmaniosis.