The characteristics of tuberculosis (TB) patients related to a chain of recent TB transmissions were investigated. Mycobacterium tuberculosis (MTB) isolates (120) were genotyped using the restriction fragment length polymorphism-IS6110 (R), spacer oligotyping (S) and mycobacterial interspersed repetitive units-variable number of tandem repeats (M) methods. The MTB isolates were clustered and the clusters were grouped according to the similarities of their genotypes. Spearman’s rank correlation coefficients between the groups of MTB isolates with similar genotypes and those patient characteristics indicating a risk for a pulmonary TB (PTB) chain transmission were ana- lysed. The isolates showing similar genotypes were distributed as follows: SMR (5%), SM (12.5%), SR (1.67%), MR (0%), S (46.67%), M (5%) and R (0%). The remaining 35 cases were orphans. SMR exhibited a significant correlation (p < 0.05) with visits to clinics, municipalities and comorbidities (primarily diabetes mellitus). S correlated with drug consumption and M with comorbidities. SMR is needed to identify a social network in metropolitan areas for PTB transmission and S and M are able to detect risk factors as secondary components of a transmission chain of TB.

Background. In Mexico, a steady increase of patients with visceral leishmaniasis has been reported, especially in the states of Chiapas and Guerrero, yet only limited information exists on canine leishmaniasis in areas of visceral leishmaniasis in Mexico. A veterinary report of dogs with nonhealing cutaneous lesions in Pungarabato, Guerrero led us to investigate the possible presence of Leishmania infection in an area where Lutzomyia longipalpis and Lutzomyia evansi, both vectors of Leishmania infantum, have been described. Methods. We analyzed skin lesions of 25 dogs by immunohistochemistry and PCR. Results. We found a 60% prevalence of Leishmania-infected dogs, the infection rate being higher in males than females. Thus, we established a new focus of canine leishmaniasis, and although to date no patients have been reported in this municipality, it is close to and shares the same ecological characteristics of dry tropical forests as regions where visceral leishmaniasis has been reported in Mexico. We also include updated information of localities of visceral leishmaniasis in Mexico as well as the distribution of possible sand fly vectors. Conclusions. Our data show the need to ascertain the magnitude of this new focus in view of the current data on human visceral leishmaniasis, a disease that is surging in Mexico.