Search

The causative agent of cutaneous leishmaniasis, Leishmania major, was studied in a Tunisian population of the fat sand rat, Psammomys obesus. Seasonal changes in the abundances of parasite and host were monitored in a longitudinal field survey lasting 21 months. Overall, 566 P. obesus, collected during 10 trapping sessions between May 1995 and January 1997, were examined. Analysis of prevalence, using logistic regression, revealed that extrinsic factors, such as season and climatic conditions, and intrinsic factors, such as host age, have a combined effect. Leishmania major showed a seasonal pattern, with most transmission occurring in late summer and in autumn, when prevalences were 7.5- and 6.6-fold higher, respectively, than in spring. Prevalence peaked, at 70%, in September 1995 and then decreased to 0% in June 1996. The same temporal fluctuation was observed during the second study year, albeit among prevalences that were relatively low because of unusually dry conditions. Prevalence was highly dependent on the age of the P. obesus, and season and age acted in synergy so that the rodents were highly infected in late summer and in autumn. Prevalence was not correlated with the relative density of the P. obesus and also appeared independent of gender. Although the ear lesions observed on 378 sand rats during a 1-year survey were closely associated with Leishmania infection, such lesions were not good predictors of infection, as 35% of the rodents found to be infected had no visible lesions on their ears. The prevalences of Leishmania infection observed in this study, among P. obesus living in monospecific colonies, were generally lower than those observed in other studies of P. obesus. It seems possible that P. obesus living in monospecific colonies could have a lesser role in propagating the parasite than those living in plurispecific colonies of rodents, and act as an 'epidemiological sink'. [ABSTRACT FROM AUTHOR]

Two bacterial and one protozoan blood parasite, belonging to the genera Bartonella, Borrelia and Babesia, were studied in a Tunisian population of Psammomys obesus. Seasonal changes in the abundance of the parasites and host were monitored in a longitudinal field survey lasting 17 months. Blood samples collected during eight rodent-trapping sessions, between September 1995 and January 1997, were examined microscopically. Bartonella sp. showed a seasonal pattern, with most transmission occurring in summer and autumn; most rodents (90%) were infected in August-September, when they were at low density and adult. Borrelia sp. showed low prevalences, with few seasonal fluctuations, and Babesia sp. showed an intermediate pattern, differing from one year to another. In the cohort of adult rats, infections with Bartonella sp. and Babesia sp. were less prevalent in winter than in the previous summer. Single and mixed infections were equally prevalent in females and males, and in sexually active and inactive adults. In addition, infection had no apparent effect on the weight of adult P. obesus. The observation that the proportion of erythrocytes infected with Bartonella sp. decreased with increasing host age is probably indicative of some acquired immunity to this micro-organism. The absence of detectable infections with Borrelia sp. in old rats indicates that the prevalence and/or intensity of infection declines with host age or that infected animals die selectively. However, there was no indication that any of these parasites combined sufficient pathogenicity and abundance to have any measurable effect on the rodent population. [ABSTRACT FROM AUTHOR]

Leishmaniasis, a public health problem in Tunisia, are diseases caused by different Leishmania species. Cutaneous leishmaniasis is present from the North to the South under different forms, due to Leishmania (L.) major, L. infantum or L. tropica. Whereas, Psammomys (P.) obesus is the confirmed reservoir host of L. major, those of L. tropica and dermotropic L. infantum wait to be identified. Importantly, P. vexillaris species have been recently highlighted; however, no studies have been carried out to explore its potential role in leishmaniasis epidemiology. Seventy two rodents were collected from Central and South-West of Tunisia between 2007 and 2010. Using several methods, 43 animals were identified as P. obesus and 29 as P. vexillaris. Leishmania kinetoplast DNA was detected in liver samples by real-time PCR in 18 P. obesus and in 8 P. vexillaris. Then, the direct sequencing of the amplified internal transcribed spacer 1, allowed the identification of L. infantum DNA in five P. obesus and in three P. vexillaris, as well as L. tropica DNA in three other P. vexillaris. Whereas, PCR fluorescent fragment length analysis of the 7 spliced leaders, allowed identifying L. major among infected P. obesus and P. vexillaris, and interestingly co-infection (L. major/L. infantum) among two P. obesus. We report here for the first time, the infection of P. obesus, from Central Tunisia, by L. infantum. Suggesting that P. obesus the known reservoir host of L. major, may also serve as reservoir host for L. infantum and thus play a role in the spread of sporadic cutaneous or visceral leishmaniasis in this region. Of equal importance, this work establish for the first time, the natural infection of P. vexillaris by different Leishmania species, suggesting its potential epidemiological role as reservoir host., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A gp63PCR method was evaluated for the detection and characterization of Leishmania (Leishmania) (L.) parasites in canine lymph node aspirates. This tool was tested and compared to other PCRs based on the amplification of 18S ribosomal genes, a L. infantum specific repetitive sequence and kinetoplastic DNA minicircles, and to classical parasitological (smear examination and/or culture) or serological (IFAT) techniques on a sample of 40 dogs, originating from different L. infantum endemic regions in Tunisia. Sensitivity and specificity of all the PCR assays were evaluated on parasitologically confirmed dogs within this sample (N = 18) and control dogs (N = 45) originating from non-endemic countries in northern Europe and Australia. The gp63 PCR had 83.5% sensitivity and 100% specificity, a performance comparable to the kinetoplast PCR assay and better than the other assays. These assays had comparable results when the gels were southern transferred and hybridized with a radioactive probe. As different infection rates were found according to the technique, concordance of the results was estimated by (κ) test. Best concordance values were between the gp63PCR and parasitological methods (74.6%, 95% confidence intervals CI: 58.8-95.4%) or serology IFAT technique (47.4%, 95% CI: 23.5-71.3%). However, taken together Gp63 and Rib assays covered most of the samples found positive making of them a good alternative for determination of infection rates. Potential of the gp63PCR-RFLP assay for analysis of parasite genetic diversity within samples was also evaluated using 5 restriction enzymes. RFLP analysis confirmed assignment of the parasites infecting the dogs to L. infantum species and illustrated occurrence of multiple variants in the different endemic foci. Gp63 PCR assay thus constitutes a useful tool in molecular diagnosis of L. infantum infections in dogs in Tunisia.

A follow-up study of 917 dogs was undertaken between 1994 and 1995 in the focus of visceral leishmaniasis in northern Tunisia. It permitted to assess the demography of the dog population, the importance of canine leishmaniasis (CL) and the determinants of seropositivity and mortality of dogs. Canine population was stable through time with an input of 231 dogs and an output of 218 dogs per year. The prevalence of seropositivity was 18% and 22.3% in 1994 and 1995 respectively and 90% of dogs were asymptomatic. Among 525 negative dogs in 1994 and reassessed in 1995, 78 seroconverted revealing an annual cumulative incidence of 14.74%. On the other hand, 23.47% (27/115) of seropositive dogs became negative in 1995. Age, presence of symptoms and density of dogs were independently associated with CL seropositivity. These results demonstrate the difficulty of control strategies of visceral leishmaniasis targeting the dog population.

The female of Phlebotomus chadlii Rioux, Jumminer & Gibily, 1966 is described and illustrated for the first time from a specimen collected in El Kef region, northwest Tunisia. It was distinguished from P. ariasi by several characters of the spermathecae: 1) the enlarged portion of P. chadlii spermathecae duct appears smooth and better developed than that of P. ariasi; 2) in P. chadlii, this part comprises three quarters of the duct whereas, in P. ariasi, it covers only the half; 3) the spermathecae neck of P. chadlii is shorter than that of P. ariasi. The duct base is compatible with the large aedeagus size of P. chadlii male. Besides, the assignment of this female to the species P. chadlii is supported by: 1) the presence of males in the same area, over the last three years; 2) the total absence in this area of P. ariasi; 3) the concomitant presence, in the same trap station, of the described female with P. chadlii males.

Toxoplasma antibodies prevalence was studied in the north of Tunisia where a mild climate prevails. Two groups of individuals were investigated: 857 living in rural area and 564 living in urb town. Sera were analysed by ELISA and indirect immunofluorescence. The overall prevalence was 58.4%. It roses from 24.5% at ten years to 52.1% at 20 years of age. A maximum level, around 70%, was reached by about 30 years. The risk of acute infection after this age seemed low as judging by the proportion of high antibodies titers observed in this group (14.2% before 30 years vs 3.7% after). A significantly higher prevalence was detected in urban residents (67% vs 52.8%). In this group, the rate of seroconversion seems the highest between ten and 20 years of age and the majority of women are infected before reaching childbearing age. In the rural area, the seropositivity is lower between ten-20 years and many women at childbearing age still susceptible to toxoplasmosis. The risk of acute infection seems higher in the youngest ones as showed by the proportion of high antibodies titers observed in the 18-30 age group (9.2%) compared to the one observed after 30 years (1.9%).

The gp63 encoding genes were characterized by PCR-RFLP in 35 isolates representative of the Leishmania donovani complex (L. infantum, L. donovani, L. archibaldi and L. chagasi), with special attention to Mediterranean L. infantum from different geographical origins, and in separate groups from Old World Leishmania (L. major, L. tropica and L. aethiopica). The aim was to evaluate how the possible selective pressure by the host on these important surface proteins would influence structuring of our sample. Comparison was carried out with the structure obtained (i) from reported isoenzyme data, characters supposed to vary neutrally, and (ii) from PCR-RFLP analysis of gp63 inter-genic regions, containing nontranslated spacers and regulatory genes. Polymorphism within the gp63-encoding region, was much higher than in gp63 inter-genic regions. In the gp63 intra-genic dendrogram, the 4 species of L. donovani complex were discriminated and quite distinct from outgroups. Within L. infantum, geographical structuring was observed and did not overlap with the structure built-up from isoenzymes and inter-genic data. These results support the idea of a strong host-selection on gp63, at vector level but most of all at vertebrate (human or dog) immunological level. Furthermore, they illustrate how the nature of genetic characters may influence the perception of population structuring.

Direct agglutination test (DAT) is a simple ans economical technique for visceral leishmaniasis diagnosis. An evaluation, held in Tunisia with 41 confirmed visceral leishmaniasis cases and 58 negative controls, showed a sensitivity of 95.1% and a specificity of 96.5%. These results were highly correlated with those of ELISA and fluorescent antibody test. The use of DAT in our country will be very relevant, mainly in district hospitals, where others classical tests are not available. It will also be useful during sero-epidemiological studies on both human and canine visceral leishmaniasis.

The epidemiology, clinical patterns, and spatial spread of Mediterranean visceral leishmaniasis were retrospectively studied in central Tunisia. The clinical profile of the disease was typical of the Mediterranean infantile form. Malnutrition and associated infectious diseases were observed in 62.5% and 55% of cases, respectively. The case-fatality rate was 6.2% and resistance to meglumine antimonate was observed in 1.6% of patients. The annual incidence of cases increased from approximately 10 cases per year before 1991 to approximately 50 cases per year between 1992 and 1994. The cumulative incidence was 133.7/100,000 among children aged < 15 years. This increase was preceded by 3 years of high mean annual rainfall in the region. The spatial distribution of the incidence of the infection through time showed an aggregation of cases in the northern part of the area where intensive agriculture projects took place during the last 10 years, leading to the establishment of a stable Leishmania infantum transmission cycle below the Atlas mountain chains, and an evident tendency to a progressive extension to the south.

Localized cutaneous leishmaniasis caused by Leishmania major is polymorphic in its clinical presentation and evolution. Clinical and parasitologic features and disease evolution of 112 Tunisian patients was evaluated. The expression of interleukin (IL)-4, IL-6, IL-10, IL-12 (p40), interferon (IFN)-gamma, and tumor necrosis factor (TNF)-alpha mRNA was analyzed by reverse transcription-polymerase chain reaction in 73 biopsies. Cytokine mRNA expression varied individually over a wide range; TNF-alpha, IL-6, and IFN-gamma were detectable in >90% of lesions, IL-12 and IL-10 in 40% and 70%, respectively, and IL-4 in only 9%. Statistical analysis demonstrated positive association between the level of IL-12 and IFN-gamma and the presence of parasites in the lesions. Unfavorable evolution of the lesions was positively associated with high IL-10, IL-12, and IFN-gamma mRNA expression. These results indicate that an unfavorable clinical outcome was not related to an inadequate Th1 cell response and suggest that the macrophage-activating effect of IFN-gamma may be inhibited by the concomitant expression of IL-10.

Thanks to the national programme of malaria eradication carried out between 1968 and 1972, there has been no active transmission of the parasitosis in Tunisia since the last indigenous case in 1979. Since 1980, with the increase in international exchanges especially with sub-Saharian countries, only imported cases of malaria have been reported in Tunisia. A retrospective and thorough survey of malaria cases diagnosed in the laboratory of parasitology of the Pasteur Institute in Tunis from 1980 to 1995 determined the epidemiological characteristics of this imported parasitosis. All in all, during the sixteen years following eradication, 245 cases were registered. The majority of cases (86.2%) was diagnosed by a systematic control of groups at risk within the national programme of malaria eradication. The remaining 13.8% cases sought medical advice when clinical symptoms appeared after their return from endemic countries. The population most affected by imported malaria were men (sex-ratio: 6.8) aged between 20 and 40 years (76% of cases); 38% were Tunisians having sojourned in an endemic country, essentially students from sub-Saharian Africa. The presumed country of contamination was African in 92.7% of the cases. Entrance into Tunisia by patients was mainly by air; 4% of the registered cases had come by land from Algeria. Sound knowledge of the epidemiological characteristics of imported malaria would make for a better follow-up of the affected population and thus reduce the probability of repeated transmission.

A randomized, placebo-controlled, double-blind trial was carried out in 1992 in central Tunisia to assess the tolerability and efficacy of paromomycin ointment against zoonotic cutaneous leishmaniasis caused by Leishmania major. One hundred fifteen patients, 2--60 years of age, with a single lesion of parasitologically confirmed cutaneous leishmaniasis, were included in the trial. The ointment was applied twice a day from day 1 through day 14. Clinical and parasitologic evaluations of lesions were done at days 0, 15, 45, and 105. Fifty-seven patients were allocated the treatment and 58 the placebo. Based on local toxicity and laboratory evaluation, there was no difference in tolerability between the two groups. Parasitologic evaluation at day 15 showed that 74.5% of the treated group had negative smears compared with 56.4% among controls (P = 0.06). This difference was no longer apparent at days 45 and 105. Clinical evaluation at days 15, 45, and 105 did not indicate any difference between the two groups. The clinical evaluation at day 15 was a good predictor of the final prognosis of the lesion in the two groups when analyzed separately, suggesting no clinical relapse in either group. These findings suggest that paromomycin ointment should not be used in the present formulation as a treatment for zoonotic cutaneous leishmaniasis in Tunisia.

Recombinant DNA probes from a genomic Leishmania major library were screened for their potential to distinguish among Old World Leishmania taxa by Southern blot analysis. A probe, pDK10, was selected and tested on a panel of 58 Old World Leishmania strains that had already been typed isoenzymatically; these strains belong to the different species described so far and had been isolated from various hosts and vectors in 14 countries. In the present study, 45 zymodemes were represented. Using the pDK10 probe, we were able to differentiate between the different phenetic complexes. No variations in hybridization patterns were found within these complexes. In addition, there was a good concordance between identification based on DNA hybridization with the pDK10 probe and that based on isoenzyme typing. The probe has been applied in identifying Leishmania strains that were isolated in Tunisia from humans, animals, or insects. Our results show that the application of the pDK10 probe, in combination with a Pst I digestion of Leishmania DNA, could be a possible alternative to isoenzyme analysis for the identification of Leishmania strains.

A diagnostic kinetoplast deoxyribonucleic acid (DNA) probe has been used to identify as Leishmania infantum amastigotes taken from the lesions (in dermal fluid or lesion triturates) of 7 of 8 patients suffering from sporadic cutaneous leishmaniasis in north Tunisia. All 8 isolates were very difficult to culture but, subsequently, sufficient parasites of one isolate have been grown for isoenzyme typing, and were identified as zymodeme MON 24 of L. infantum. The advantages of using recombinant DNA probes for the identification of parasites from lesions are discussed.

Seventeen (17) parasitologically confirmed cases of infantile kala azar (KA) are reported from 1982 to 1991 in Tunisia, in areas (Gouvernorates of Sidi Bouzid, Kasserine, Sfax, Gafsa and Tozeur) where the disease has never (or exceptionally) been reported before. This tendency to the extension of the KA areas from Northern Tunisia to the Central and Southern parts could be explained by the ecological modifications that occurred in these zones following agriculture development programs that included an important increase of water resources (wells, dams etc...). These modifications probably contributed to the enhancement of the Leishmania infantum vector population densities making it possible for transmission cycles to be implemented and maintained in these areas; the parasite could have been brought with dogs from the North of the country.

Forty-two Tunisian patients suffering from Hymenolepis nana infection, were treated with 500 mg tablets of mebendazole, 3 times a day, 3 consecutive days for 5 patients (group I) and 4 consecutive days for 37 patients (group II). The faeces were examined during the third and fifth week, after treatment. 18 (42.8%) patients, 2 from group I and 16 from group II, were cured. The tolerance of the product was excellent and there were no adverse side-effects.

An entomological survey carried out in 1985 in the zoonotic cutaneous leishmaniasis foci of the Center of Tunisia (Sidi Bouzid Governorate), showed the presence of 7 phlebotomine species. Phlebotomus (P) papatasi, the most abundant species (84.6%), was essentially trapped in rodent burrows. Its anthropophily was demonstrated by man-baiting catch. The highest population density was observed during July and August, for P. papatasi. Its role in the transmission of Z. C. L. in Tunisia is discussed. P. perniciosus, less abundant (13.2%) was mostly trapped in animal resting places. Only few specimens of P. longieuspis, P. perfiliewi, Sergentomyia (S) minuta, S. antennata and S. dreyfussi were observed.

From an analysis of 1,546 cases of cutaneous leishmaniasis collected throughout Tunisia three clinico-epidemiological forms could be determined. These forms are due to three different species of Leishmania and are observed in different geographical areas. Sporadic cutaneous leishmaniasis (SCL), 63 cases. This form is found in Northern Tunisia, in known foci of Kala-azar. 96% of the patients have a single, small, ulcerated and crusty lesion on the face surrounded by an important zone of infiltration. Amastigotes are less than 4 microns in diameter, and it is very difficult to maintain the parasites in cultures. This form is probably due to Leishmania infantum, as has been demonstrated in Algeria in a similar form evolving in the same biotope as the Tunisian form. The vector and reservoirs of SCL are unknown. Zoonotic cutaneous leishmaniasis (ZCL), 1,412 cases. The disease is epidemic in Central and Southern Tunisia. The lesions are multiple; they affect the limbs more frequently than the face and heal in less than 8 months. They are polymorphous, usually large and superinfected. There is a seasonal occurrence of the outbreaks (summer and autumn). Amastigotes are large (4 to 6.5 microns in diameter) and the parasites easily grow in cultures. This form is caused by Leishmania major, and its vector is Phlebotomus papatasi. Three species of rodents harbour the parasite. Anthroponotic cutaneous leishmaniasis (ACL), 71 cases. This form is endemic in South-Eastern Tunisia. 70% of the patients present with single lesions, one half of which affect the face. Dry and proliferating lesions are the most frequent.(ABSTRACT TRUNCATED AT 250 WORDS)

The presence of Phlebotomus papatasi naturally infected with Leishmania (2 females out of 24), is reported for the first time, in a Tunisian zoonotic cutaneous leishmaniasis focus.

Three serological surveys were conducted for mass detection of hydatidosis in Tunisia. Microtubes were used for sampling of serum and plasma eluates were tested by the E. L. I. S. A. technique. More than 2,500 persons, mainly originating from rural areas (Souks, primary schools, military recruits, village dispensaries) were studied. 2/3 of individuals examined simultaneously underwent abdominal echotomography the findings of which were compared to those of serology. The whole data were discussed with respect to current status of hydatidosis in Tunisia.