BackgroundOld world Zoonotic Cutaneous Leishmaniasis (ZCL) is a vector-borne human disease caused by Leishmania major, a unicellular eukaryotic parasite transmitted by pool blood-feeding sand flies mainly to wild rodents, such as Psammomys obesus. The human beings who share the rodent and sand fly habitats can be subverted as both sand fly blood resource. ZCL is endemic in the Middle East, Central Asia, Subsaharan and North Africa. Like other vector-borne diseases, the incidence of ZCL displayed by humans varies with environmental and climate factors. However, so far no study has addressed the temporal dynamics or the impact of climate factors on the ZCL risk.Principal FindingsSeasonality during the same epidemiologic year and interval between ZCL epidemics ranging from 4 to 7 years were demonstrated. Models showed that ZCL incidence is raising i) by 1.8% (95% confidence intervals CI:0.0–3.6%) when there is 1 mm increase in the rainfall lagged by 12 to 14 months ii) by 5.0% (95% CI: 0.8–9.4%) when there is a 1% increase in humidity from July to September in the same epidemiologic year.Conclusion/SignificanceHigher rainfall is expected to result in increased density of chenopods, a halophytic plant that constitutes the exclusive food of Psammomys obesus. Consequently, following a high density of Psammomys obesus, the pool of Leishmania major transmissible from the rodents to blood-feeding female sand flies could lead to a higher probability of transmission to humans over the next season. These findings provide the evidence that ZCL is highly influenced by climate factors that could affect both Psammomys obesus and the sand fly population densities.

A study was undertaken between November 2008 and March 2010, in the focus of cutaneous leishmaniasis of Central Tunisia, to evaluate the role of Psammomys obesus (n = 472) and Meriones shawi (n = 167) as reservoir hosts for Leishmania major infection. Prevalence of L. major infection was 7% versus 5% for culture ( p = not signifiant [NS]), 19% versus 16% for direct examination of smears ( p = NS), and 20% versus 33% ( p = NS) for Indirect Fluorescent Antibody Test among P. obesus and M. shawi, respectively. The peak of this infection was in winter and autumn and increased steadily with age for the both species of rodents. The clinical examination showed that depilation, hyper-pigmentation, ignition, and severe edema of the higher edge of the ears were the most frequent signs observed in the study sample (all signs combined: 47% for P. obesus versus 43% for M. shawi; p = NS). However, the lesions were bilateral and seem to be more destructive among M. shawi compared with P. obesus. Asymptomatic infection was *40% for both rodents. This study demonstrated that M. shawi plays an important role in the transmission and the emergence of Leishmania major cutaneous leishmaniasis in Tunisia.

BackgroundZoonotic Cutaneous Leishmaniasis (ZCL) due to Leishmania major (L. major) is still a serious public health problem in Tunisia. This study aimed to compare the prevalence and risk factors associated with L. major infection in old and new foci using leishmanin skin test (LST) in central Tunisia.MethodsA cross sectional household survey was carried out between January and May 2009 on a sample of 2686 healthy individuals aged between 5 and 65 years. We determined the prevalence of L. major infection using the LST. Risk factors of LST positivity were assessed using a logistic regression model.ResultsThe overall prevalence of LST positivity was 57% (95% CI: 53–59). The prevalence of L. major infection was significantly higher in the old focus (99%; 95% CI: 98–100) than in the emerging foci (43%; 95% CI: 39–46) (p = <0.001). Multivariate analysis of LST positivity risk factors showed that age, the nature of the foci (old/emerging), personal and family history of ZCL are determinants of positive LST results.ConclusionThe results updated the current epidemiologic profile of ZLC in central Tunisia. Past history of transmission in a population should be considered as a potential confounder in future clinical trials for drugs and vaccines against L. major cutaneous leishmaniasis.

Densities, ρ, and dynamic viscosities, η, of triethylamine + water (TEA−W) binary mixtures have been determined experimentally in the single phase region and over the whole composition range at T = (283.15 to 291.35) K. The experimental measurements of these properties were carried out at atmospheric pressure. Results have been fitted to obtain the adjustable parameters and standard deviations between the measured and fitted values, respectively. The viscosity data have been also correlated with the equations of Grunberg−Nissan, Hind et al., Katti−Chaudhri, Heric−Brewer, McAllister, and Auslander.

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Measurements of the coexistence curve of the binary-fluid mixture isobutyric acid + water with added KCl salt at various concentrations show an important dependence on the critical temperature and the critical exponent β. The phase-transition region shifts as a function of the salt concentration. The effective -critical exponent β * = (0.266-0.293) is neither compatible with the Ising value β = 0.325 nor with the Fisher renormalized value ∼ 0.365.

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