Abstract
Vector-borne transmission of Chagas disease has become an urban problem in the city of Arequipa, Peru, yet the debilitating symptoms that can occur in the chronic stage of the disease are rarely seen in hospitals in the city. The lack of obvious clinical disease in Arequipa has led to speculation that the local strain of the etiologic agent, Trypanosoma cruzi, has low chronic pathogenicity. The long asymptomatic period of Chagas disease leads us to an alternative hypothesis for the absence of clinical cases in Arequipa: transmission in the city may be so recent that most infected individuals have yet to progress to late stage disease. Here we describe a new method, epicenter regression, that allows us to infer the spatial and temporal history of disease transmission from a snapshot of a population's infection status. We show that in a community of Arequipa, transmission of T. cruzi by the insect vector Triatoma infestans occurred as a series of focal micro-epidemics, the oldest of which began only around 20 years ago. These micro-epidemics infected nearly 5% of the community before transmission of the parasite was disrupted through insecticide application in 2004. Most extant human infections in our study community arose over a brief period of time immediately prior to vector control. According to our findings, the symptoms of chronic Chagas disease are expected to be absent, even if the strain is pathogenic in the chronic phase of disease, given the long asymptomatic period of the disease and short history of intense transmission. Traducción al español disponible en Alternative Language Text S1/A Spanish translation of this article is available in Alternative Language Text S1
Highlights
Chagas disease, responsible for more deaths in the Americas than any other parasitic disease [1], has become an urban problem in the city of Arequipa, Peru [2,3]
A model with four micro-epidemics had the greatest support from the observed data; the odds in favor of this model compared to the single-epidemic model increased 15-fold after considering the observed data (Figure 1)
When we tabulated the exposure time and risk of infection of individuals in the population in the fourepicenter model we found that around half of infections occurred in the 5 years previous to disruption of transmission through insecticide application, and 90% of infections occurred over a period of 12 years (Figure 2)
Summary
Responsible for more deaths in the Americas than any other parasitic disease [1], has become an urban problem in the city of Arequipa, Peru [2,3]. The debilitating symptoms of chronic Chagas disease, common across southern South America, are rarely seen in hospitals in the city The vast majority of the 8–10 million individuals infected with T. cruzi [7] have the indeterminate form of Chagas disease. These individuals exhibit no symptoms or signs of their infection, but 20% to 30% are expected to progress to cardiac or digestive forms of chronic Chagas disease, which are difficult to treat and potentially fatal [8,9,10]. Treatment with existing antitrypanosomal drugs, benznidazole or nifurtimox, appears to slow or prevent disease progression [9], but treatment is thought to be more effective when administered early in the course of infection [11]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
