Modelling the number of dermal lesions in anthroponotic cutaneous leishmaniasis and its associated factors in Herat province, western Afghanistan, during 2012-2013.

Cutaneous leishmaniasis (CL), caused by Leishmania tropica, is the main causative agent of CL in the Herat province, western Afghanistan. In CL patients, one of the most important indicators for reducing the amount of body damage and the choice of treatment is the number of dermal lesions, but there is no strong evidence in this regard. Therefore, using count regression models, the main objective of this historical cohort study was to identify the distribution of the number of dermal lesions and determine the associated factors among CL patients referring to leishmaniasis reference laboratory in Herat province, from January 2012 to December 2013. In a total of 4,127 clinically suspected CL cases, 50.20% were female and 49.80% male. Based on the results of ZINB model, which is the best model suggested by goodness-of-fit criteria, age variables (IRR = 1.007), duration of lesion (6-12 weeks compared to < 6 weeks with IRR = 1.36 and >12 weeks with IRR = 1.39 compared to <6 weeks), type of lesion(both nodule and ulcer compared to papule with IRR = 2.03), location of lesion (trunk with IRR = 1.90, upper with IRR = 1.66, lower with IRR = 1.61 and mix with IRR = 10.35 compared to head/neck/ears) and type of lesion (ulcer compared to papule with IRR = 0.50, nodule and lupoid, respectively, as IRR = 0.72 and IRR = 0.51 compared to papule) had a significant effect on the mean number of dermal lesions (p < .05). Also, our results showed that among four models used, the ZINB model represented a better performance to determine the associated probable factors about the number of dermal lesions in ACL patients. Moreover, there was a direct association between age and number of dermal lesions; in addition, duration of lesion, type of lesion and location of lesion had a significant effect on the number of dermal lesions. Therefore, a comprehensive planning is necessary for controlling and reducing the number of dermal lesions.