Call to action: A literature review of Chagas disease risk in California 1916–2018

Abstract

Human Chagas disease (CD), caused by the Trypanosoma cruzi infection, is considered nonendemic in the United States of America [https://www.cdc.gov/parasites/chagas/gen_info/ detailed.html#intro; consulted March 29, 2020], assuming that this chronic affection’s epidemiology is different from that of Latin American countries. The attention is mostly focused on blood bank screening, organ donation, and vertical (mother to child) transmission [1]. This approach can overlook the potential for autochthonous transmission of T. cruzi, particularly in the light of a recent acknowledgment about the role that vectorial transmission may have on the CD in the USA. A low awareness among physicians about CD risk besides its migratory origin can contribute to an existing underreporting rate, thus masking the accurate estimation of CD burden in the USA [2]. Cases of autochthonous infection in the USA are not accurately tracked since it is only mandatory to report it in seven states, i.e., Arizona, Arkansas, Louisiana, Mississippi, Tennessee, Texas, and Massachusetts [3]. However, as it occurs in Latin America, where the index of suspicion is much higher, acute T. cruzi infections in immunocompetent individuals can pass undiagnosed and undetected among residents [4]. In the USA, 238,091 cases are estimated as of 2012 [5]. This analysis highlighted the role of Latin immigrants in the CD burden, with California being the state with the highest estimated number of cases. Although imported CD cases are undoubtedly a matter of concern, there are also environmental conditions leading to autochthonous infections [6]. New encounters between humans and triatomine bugs are often associated with the destruction of or invasion into vertebrate hosts’ habitats, compromised housing structures, or both. Disruption of host burrows provokes the bugs to seek new refugees, and their attraction to artificial light often leads them to nearby human dwellings [7]. Multiple publications have highlighted the southern USA as an area where autochthonous infection occurs, mainly because of the high proportion of impoverished residents living in substandard housing infested by triatomines [7–10]. It is essential to improve our knowledge of T. cruzi infection risk components because there are parasite reservoirs among wildlife species and vectors living in contact with humans [11]. This is especially found in less-studied regions such as California, where the epidemiological, parasitological, and entomological patterns of T. cruzi transmission might resemble those of other endemic areas. Surveillance of infection prevalence among local populations of Triatominae is critical for accurate assessment of the public health risk. We attempt to contribute to this with an extensive historical literature review of records of autochthonous T. cruzi and human-related data for CD in California. This method of review provides a contemporary account of this topic’s breadth of knowledge. There has been no recent review of this theme at PLOS NEGLECTED TROPICAL DISEASES