High levels of infectiousness of asymptomatic Leishmania (Viannia) braziliensis infections in wild rodents highlights their importance in the epidemiology of American Tegumentary Leishmaniasis in Brazil

• Published in: PLOS Neglected Tropical Diseases
• Main Authors: Marinho-Júnior, José Ferreira, Monteiro, Juliana F. C. L. S., Sales de Carvalho, Ana Waléria, de Carvalho, Francisco Gomes, de Paiva Cavalcanti, Milena, Shaw, Jeffrey, Courtenay, Orin, Brandão-Filho, Sinval Pinto
• Format: Text
• Language: English
• Published: Public Library of Science 2023
• Subjects: Research Article; Rattus rattus
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9910795/; http://www.ncbi.nlm.nih.gov/pubmed/36716345; https://doi.org/10.1371/journal.pntd.0010996

BACKGROUND: The epidemiological significance of wildlife infections with aetiological agents causing human infectious diseases is largely determined by their infection status, contact potential with humans (via vectors for vector-borne diseases), and their infectiousness to maintain onward transmission. This study quantified these parameters in wild and synanthropic naturally infected rodent populations in an endemic region of tegumentary leishmaniasis in northeast Brazil. METHODS: Capture-mark-recapture (CMR) of rodents was conducted over 27 months in domestic/peri domestic environs, household plantations and nearby Atlantic Forest (9,920 single trap nights). Rodent clinical samples (blood and ear tissue) were tested for infection by conventional PCR and quantitative PCR (qPCR) for Leishmania (Viannia) braziliensis, and xenodiagnosis to measure infectiousness to the local sand fly vector. RESULTS: A total 603 individuals of 8 rodent species were (re)captured on 1,051 occasions. The most abundant species were Nectomys squamipes (245 individuals, 41% of the total catch), Rattus rattus (148, 25%), and Necromys lasiurus (83, 14%). All species were captured in greater relative frequencies in plantations; R. rattus was the only species captured in all three habitats including in and around houses. Four species, comprising 22.6% of individuals captured at least twice, were geolocated in more than one habitat type; 78.6% were infected with L. (V.) braziliensis, facilitating inter-species and inter-habitat transmission. Species specific period prevalence ranged between 0%-62% being significantly higher in N. squamipes (54–62%) and Hollochillus sciureus (43–47%). Xenodiagnosis was performed on 41 occasions exposing 1,879 Nyssomyia whitmani sand flies to five rodent species (37 individuals). Similar mean levels of infectiousness amongst the more common rodent species were observed. Longitudinal xenodiagnosis of the N. squamipes population revealed a persistent level of infectiousness over 13 months follow-up, infecting a ...