Population Characteristics of Human-Commensal Rodents Present in Households from Mérida, Yucatán, México

Anthropocommensal rodents live in close proximity to humans in many habitats around the world. They are a threat to public health because of the pathogens they carry. Recent studies in Mérida, Yucatán, México, have shown that commensal rodents harbor potential zoonotic pathogens such as bacteria, helminths, and viruses. In this study, we describe reproductive and demographic parameters of house mice and black rats present in households from Mérida, Yucatán, México, a municipality located in a tropical region in southern México. Rodents were trapped in 142 households within the municipality of Mérida from 2011 to 2014. A total of 832 rodents were trapped, constituting 556 (66.8%) house mice (Mus musculus) and 276 (33.2%) black rats (Rattus rattus). The sex ratio in mice was different than parity, while in rats it was 1:1. Mice in the weight class 8.1–12 g were most abundant in both females (52.9%) and males (57.2%). On the other hand, rats weighing ≤ 40 g (25% of females and 28.6% of males) were most abundant. The percentage of pregnancy in mice was 46.7%, whereas in rats it was 21.3%. The mean number of embryos was 4.7 and 5.8 in mice and rats, respectively. This study provides relevant demographic information on the ecology of commensal rodents from a tropical region of Latin America. We consider that our findings could be useful as a first step toward understanding the ecological behavior of rodent populations in tropical regions