title: Temporal dynamics and impact of climate factors on the incidence of zoonotic cutaneous leishmaniasis in central Tunisia.
abstract: BACKGROUND
  Old 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.
  
  
  RESULTS
  Seasonality 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.
  
  
  CONCLUSIONS
  Higher 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.
authors.affiliation: Laboratory of Medical Epidemiology, Pasteur Institute of Tunis, Tunis, Tunisia. toumiamine@gmail.com
authors.forename: Amine
authors.initials: A
authors.lastname: Toumi
authors.forename: Sadok
authors.initials: S
authors.lastname: Chlif
authors.forename: Jihene
authors.initials: J
authors.lastname: Bettaieb
authors.forename: Nissaf
authors.initials: N
authors.lastname: Ben Alaya
authors.forename: Aicha
authors.initials: A
authors.lastname: Boukthir
authors.forename: Zaher E
authors.initials: ZE
authors.lastname: Ahmadi
authors.forename: Afif
authors.initials: A
authors.lastname: Ben Salah
mesh_terms: D000818:Animals; D019663:Chenopodiaceae / Q000254:growth & development; D002980:Climate; D017753:Ecosystem; D005260:Female; D006801:Humans; D015994:Incidence; D018320:Leishmania major / Q000302:isolation & purification*; D016773:Leishmaniasis, Cutaneous / Q000453:epidemiology* / Q000469:parasitology; D011576:Psychodidae / Q000254:growth & development; D012377:Rodentia / Q000254:growth & development; D012621:Seasons; D014416:Tunisia / Q000453:epidemiology; D015047:Zoonoses / Q000453:epidemiology* / Q000469:parasitology