Phlebotomus (Paraphlebotomus) riouxi: a synonym of Phlebotomus chabaudi without any proven vectorial role in Tunisia and Algeria.

Phlebotomus (Paraphlebotomus) riouxi Depaquit, Léger & Killick-Kendrick (Diptera: Psychodidae) was described as a typological species based on a few morphological characters distinguishing it from Phlebotomus (Paraphlebotomus) chabaudi Croset, Abonnenc & Rioux. The naming of P. riouxi coincided with its incrimination as a rural vector of Leishmania tropica Wright (junior synonym: Leishmania killicki Rioux, Lanotte & Pratlong) in Tataouine governorate, an arid region of southern Tunisia. The current report finds insufficient evidence to incriminate either phlebotomine sandfly as a vector of L. tropica in North Africa. Phlebotomus riouxi was found not to have the characteristics of a phylogenetic or biological species, and therefore it is synonymized with P. chabaudi. Both taxa were recorded together for the first time in Tunisia, in Tataouine, where three of 12 males showed intermediate morphology and both sexes of each taxon were not characterized by specific lineages of the nuclear gene elongation factor-1α or the mitochondrial gene cytochrome b, for which a long 3' terminal fragment is recommended for phlebotomine phylogenetics. This case study indicates that the eco-epidemiology of leishmaniasis should focus more on identifying key components of vectorial transmission that are susceptible to interventions for disease control, rather than on defining sibling species of vectors.

[Current epidemiological data on visceral leishmaniasis in Tunisia]. / Actualités épidémiologiques de la leishmaniose viscérale en Tunisie.

OBJECTIVE: Visceral leishmaniasis is an important health problem in Tunisia. The aim of this study was to update the epidemiological and clinical features of the disease. DESIGN: We performed a retrospective systematic sampling of epidemiological and clinical data collected from the medical records of 1,096 cases of visceral leishmaniasis diagnosed between 1996 and 2006 all over the country. RESULTS: The mean annual incidence of cases was 99.6 cases/year. The mean annual incidence rate was 1.04 cases/100,000 inhabitants, showing an important increase compared to former studies. As expected, children under 5 years (866 cases) were the most affected with a mean annual incidence rate of 9.6 cases/100,000 (p<0.001). The geographical distribution of cases revealed the spreading of the disease from the Northern parts of the country to the Central and even to Southern ones. Rural cases (65.3%) were significantly more numerous than urban ones (34.7%), p<0.001. The sex ratio was 1.03. The diagnostic delay (average of 54 days) was considerably shortened during the study period compared to previous reports, and explains the decrease of the lethality rate (2.9%). CONCLUSIONS: Visceral leishmaniasis has been present in central Tunisia since the early 1990 s. Its incidence and the distribution area have increased. This evolution is probably linked to the development of irrigation and agriculture favorable to the multiplication of vector sandflies and dogs reservoirs of Leishmania infantum.

Population structure and geographical subdivision of the Leishmania major vector Phlebotomus papatasi as revealed by microsatellite variation.

Multi-locus microsatellite typing (MLMT) has been employed to infer the population structure of Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) sandflies and assign individuals to populations. Phlebotomus papatasi sandflies were collected from 35 sites in 15 countries. A total of 188 P. papatasi individuals were typed using five microsatellite loci, resulting in 113 different genotypes. Unique microsatellite signatures were observed for some of the populations analysed. Comparable results were obtained when the data were analysed with Bayesian model and distance-based methods. Bayesian statistic-based analyses split the dataset into two distinct genetic clusters, A and B, with further substructuring within each. Population A consisted of five subpopulations representing large numbers of alleles that were correlated with the geographical origins of the sandflies. Cluster B comprised individuals collected in the Middle East and the northern Mediterranean area. The subpopulations B1 and B2 did not, however, show any further correlation to geographical origin. The genetic differentiation between subpopulations was supported by F statistics showing statistically significant (Bonferroni-corrected P < 0.005) values of 0.221 between B2 and B1 and 0.816 between A5 and A4. Identification of the genetic structure of P. papatasi populations is important for understanding the patterns of dispersal of this species and to developing strategies for sandfly control.

[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.

Phlebotominae (Diptera: Psychodidae) of human leishmaniosis sites in Tunisia.

In order to identify the phlebotomine sandfly populations in Tunisian leishmaniosis foci, an entomological survey was carried out through three entomological seasons (2002-2003-2004) in 19 visceral and cutaneous leishmaniosis areas, located in six bioclimatic zones. Sandfly collections were based on light and sticky traps placed around human leishmaniosis cases. 8,722 phlebotomine sandflies belonging to 12 species were collected. The dominance of subgenus Larroussius species in northern foci, Phlebotomus papatasi in south-western foci and their co-dominance in the centre of the country is in accordance with the distribution of Leishmania infantum and L. major in Tunisia. The low density found in the historical zoonotic cutaneous leishmaniosis focus of Metlaoui in the south-west may indicate the high competence of the local populations. Studied phlebotomine settlements have showed a low specific diversity in most of the studied sites. In L. infantum areas, the dominant species were respectively: P. perfiliewi in the cutaneous leishmaniosis site of the humid bioclimatic stage, P. perniciosus in the cutaneous and visceral leishmaniosis foci of semi-arid and arid bioclimatic stages and P. longicuspis in the visceral leishmaniosis focus of saharan bioclimate. In the zoonotic cutaneous leishmaniosis foci, P. papatasi was a dominant species. In the well-known south-eastern foci of cutaneous leishmaniosis due to L. killicki, P. sergenti was a dominant species with P. perniciosus. In the central emerging foci of L. killicki, P. perniciosus was a dominant species in some sites whereas it was very rare in others. In these sites, the subgenus Paraphlebotomus was always present with a higher abundance of P. alexandri than P. sergenti.

Spread of Leishmania killicki to Central and South-West Tunisia.

Twenty cutaneous leishmaniasis (CL) cases were notified from December 2001 to February 2002, in a small village in the district of Oueslatia (governorate of Kairouan, central Tunisia) which is an endemic focus of infantile visceral leishmaniasis due to leishmania (L.) infantum and that had never been concerned previously by CL. The parasite typing of two isolates obtained from two children that have never left the region has identified L. killicki. This species had only been reported previously in a limited focus of Tunisian Southeast. In October 2002, an epidemiological survey with isoenzym characterization of the parasite led in a well-known focus of zoonotic cutaneous leishmaniasis of South-West Tunisia also revealed the presence of L. killicki. These results suggest the spread of this species and stress the need of further investigations for a better control of CL in Tunisia.

[Phlebotomus (Larroussius) langeroni Nitzulescu, 1930 in Tunisia: presence of the female and updating of geographical distribution]. / Phlebotomus (Larroussius) langeroni Nitzulescu, 1930 en Tunisie: présence de la femelle et actualisation de la distribution géographique.

The authors report the presence of Phlebotomus (Larroussius) langeroni Nitzulescu, 1930 in two epidemic foci of cutaneous leishmaniasis due to Leishmania infantum in northwest Tunisia. The Phlebotomus langeroni female is to be mentioned for the first time in North Africa.

[Experimental study of larval efficiency of Gambusia affinis holbrooki (GIRARD, 1859) (fish-Poecilidae)]. / Etude experimentale de l'efficacite larvivore de Gambusia affinis holbrooki (GIRARD, 1859) (Poisson-Poecilidae).

Experimental study of efficiency of Gambusia affinis holbrooki (GIRARD, 1859) (Fish-Poecilidae). Gambusia affinis is a culiciphage fish which was introduced in Tunisia in 1929 to control mosquito larvae. In the present study, we confirm, under laboratory conditions, the good efficacy of Gambusia affinis against mosquito larvae. The consumption of larvae decreases with the evolution of larvae instars and increases, for the same instar, in relation with the fish size. In fact, the size of the prey is related to the predator's size: fish belonging to the length class [20-24 mm] prefer IIIrd instar, fish from class length [25-29 mm] prefer pupae and IVth instar. The trophic test shows that G. affinis has a clear preference for Culicidae larvae, except fish belonging to the 2 length classes [35-39 mm] and [40-44 mm] for which Culicidae and Ephemeroptera have similar preference. In addition, at high temperature (30 degrees C), Gambusia affinis has a higher efficiency.