Spatial distribution of an infectious disease in a small mammal community

Abstract

Chagas disease is a zoonosis caused by the parasite Trypanosoma cruzi and transmitted by insect vectors to several mammals, but little is known about its spatial epidemiology. We assessed the spatial distribution of T. cruzi infection in vectors and small mammals to test if mammal infection status is related to the proximity to vector colonies. During four consecutive years we captured and georeferenced the locations of mammal species and colonies of Mepraia spinolai, a restricted-movement vector. Infection status on mammals and vectors was evaluated by molecular techniques. To examine the effect of vector colonies on mammal infection status, we constructed an infection distance index using the distance between the location of each captured mammal to each vector colony and the average T. cruzi prevalence of each vector colony, weighted by the number of colonies assessed. We collected and evaluated T. cruzi infection in 944 mammals and 1976 M. spinolai. We found a significant effect of the infection distance index in explaining their infection status, when considering all mammal species together. By examining the most abundant species separately, we found this effect only for the diurnal and gregarious rodent Octodon degus. Spatially explicit models involving the prevalence and location of infected vectors and hosts had not been reported previously for a wild disease.

Quantification by real-time PCR of Trypanosoma cruzi DNA in samples of Triatoma infestans used in xenodiagnosis of chronic Chagas disease patients

“…The high copy numbers of repetitive sequences contained in nuclear and kinetoplast DNA of T. cruzi [ 16 , 17 ] has allowed the successful application of PCR to detect the parasite. The XD has less sensitivity than PCR but the combination with PCR (qualitative PCR-XD) in different biological samples and hosts, improves its sensitivity [ 15 , 19 – 22 , 28 , 29 , 35 , 47 , 51 ]. The objective of this study is to detect and quantify T. cruzi in Tr.…”

Lizards and rabbits may increase Chagas infection risk in the Mediterranean-type ecosystem of South America

“…This diurnal kissing bug species occurs from 26°S to 33°S 12 and shows a conspicuous spatial aggregation, often using rocky outcrops and bromeliads as refuge ( Fig. 1B), where it exhibits a sit-and-wait strategy to parasitize vertebrate hosts 7,[13][14][15][16] . Mepraia spinolai feeds on the blood of vertebrates such as mammals, birds and reptiles 17,18 , albeit its preferred hosts consist on several small native mammals, reaching T. cruzi infection prevalence up to 70% in some rodent species 16,19 .…”

“…1B), where it exhibits a sit-and-wait strategy to parasitize vertebrate hosts 7,[13][14][15][16] . Mepraia spinolai feeds on the blood of vertebrates such as mammals, birds and reptiles 17,18 , albeit its preferred hosts consist on several small native mammals, reaching T. cruzi infection prevalence up to 70% in some rodent species 16,19 . Secondarily, the European rabbit Oryctolagus cuniculus, an invasive mammal present in this ecosystem since 1884, experiences T. cruzi infection prevalence up to 38% 20 .…”

Trypanosomatid Infections among Vertebrates of Chile: A Systematic Review

“…The distribution of the endemic insectivorous species, Thylamys elegans , overlaps with the geographic distribution of M. spinolai and T. infestans [ 10 , 12 , 13 , 28 ]. Studies of T. cruzi infection in T. elegans have shown a high variability, from the complete absence of infection when assessed by optical microscopy, serology (indirect hemagglutination; IHA, hereafter), and/or xenodiagnosis (XD, hereafter) [ 29 , 30 ], to a range of 28.6–50.0% of infection by cPCR on blood [ 14 , 17 , 31 , 32 , 33 , 34 ]. See the detailed information in Table 2 and Supplementary Materials .…”

“…Among them, 13 species have been tested for T. cruzi infection, including three Abrothrix species, two Octodon species, Abrocoma bennetti , Chinchilla lanigera , Lagidium viscacia , O. longicaudatus , Phyllotis darwini , and Spalacopus cyanus , among others. From these, seven species have been reported as being infected by T. cruzi , with a high variation in the frequency of infection, mainly depending on the detection technique: A. bennetti (0–42.9%), Abrothrix longipilis (0–9.5%), Abrothrix olivaceus (0–71.0%), C. lanigera (20.0–40.0%), Octodon degus (8.3–70.4%), O. longicaudatus (0–50.0%), and P. darwini (0–100%) [ 14 , 15 , 17 , 29 , 30 , 31 , 32 , 33 , 34 , 40 , 41 , 42 , 43 , 44 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ]. See the detailed information in Table 2 and Table S1 in Supplementary Materials .…”