We found a persistent and possibly increasing population of patients with Chagas infection in the New York City Blood Donor population. Intriguingly, Chagas positivity appears to cluster in a limited set of geographic locations of that population.
This study expands what was previously known about Chagas prevalence outside its endemic regions, particularly in the United States. Previous studies have described the prevalence of Chagas infection in the donor population of Spain (0.62%) 
, Mexico (0.75%) 
, citing two examples, but the only detailed published U.S. data is from a sample set from 1994–1998, showing a 0.19% prevalence in Los Angeles and 0.08% in Miami 
. The CDC has published more recent data in 2007 but with no detailed description of donor characteristics 
We also found geographic clustering of the donor population in areas with high Foreign Born Hispanic immigrant populations. For example, Eastern Long Island is unique in its large (50 k+) population of native Salvadorans 
, which may be mirrored by the geographic clustering of the positive donors in that area (please see ). Future efforts at identification of Trypanosoma cruzi
infected populations may benefit from this donor-population derived “map” of areas of probable increased population Chagas prevalence. This has already been seen in Europe, where two studies, one In Spain and other in Switzerland, targeted high risk immigrant populations with direct screening (not during blood donation) and found a much higher seroprevalence than previously expected. They both confirmed, for example, that the Bolivian immigrant population is at particularly high risk for Chagas infection and merits focused outreach 
. Additionally, while neither study looked at the economics of such screening, other studies indicate that even broader screening may make economic sense 
This study has several limitations. The prevalence in the Hispanic/Latino group may be underestimated due to lack of race self-identification among many donors, as 24% of Chagas positive donors did not indicate race and therefore could not be included in the “Hispanic/Latino” only results despite most studies indicating there are very few non-Hispanics with Chagas. Thus, the Hispanic/Latino prevalence could be as high as 0.067% over all three years if all the Chagas positive patients were in fact Latino. In addition, the donor's country of origin was not included in the questionnaire, and the Hispanic/Latino population in the study database was not segregated by place of birth. The Hispanic/Latino population in New York City includes Dominicans and Puerto Ricans (the largest Foreign born and the largest non Foreign born Hispanic groups in New York City, respectively 
), groups not at high risk of Chagas positivity. Otherwise our data may have better mirrored the overall trend of increasing positivity, as seen in earlier, larger studies 
. This increase would be consistent with the rise in immigration in the last decade of particular populations (i.e. rural Mexicans) with known higher Chagas positivity 
. Also of note, blood donor populations do not necessarily mirror society as a whole 
. However, this has been an accepted practice even in areas of highest Chagas seroprevalence given the difficulty of getting blood samples for the population most likely to be exposed to T. cruzi
. Finally it is important to note that no clinical follow up was available (Blood Center protocol is limited to referring them to an infectious disease physician), and thus we were unable to ascertain if any of the seropositive Donors were symptomatic.
These results indicate further analysis and outreach is warranted. Chagas Disease is an infection with both asymptomatic latency and debilitating sequelae in a substantial minority of infected patients. Identification, monitoring, and possible treatment of infected persons are best done through targeted identification and testing of at risk population groups. Diagnosis of Chagas infection in blood donors captures only a segment of the population infected with imported Chagas Disease. Characterization of high prevalence communities through blood donor seroprevalence suggests that follow up larger scale community-focused screenings of foreign-born populations could be both lifesaving and cost effective.