Dengue fever is a febrile illness found throughout the tropics that, in severe cases, can be deadly. The most rapidly spreading of any mosquito-borne disease, dengue is re-emerging as an illness of great concern in Latin America and around the globe. The CDC estimates that as many as 400 million cases of dengue occur each year. The pathogenesis of dengue virus is complicated and acts through modulation of the host immune system. Dengue polarizes the immune system balance of T helper 1 (Th1) and T helper 2 (Th2) cells towards a Th1 inflammatory response. Parasitic infections have also been shown to affect the Th1/Th2 balance of the immune response, although how these immunological changes alter the severity of dengue during possible coinfections has yet to be explored. One of the most common parasitic infections in Latin America is Trypanosoma cruzi, the etiological agent of Chagas disease. Like dengue, T. cruzi polarizes the Th1/Th2 balance of its host. By triggering a Th2 response, Chagas disease may counteract the Th1 response caused by dengue thereby masking dengue symptoms, increasing the frequency of asymptomatic infections and leading to underreporting of dengue in regions where Chagas is common. In order to begin to examine the effect of parasites on dengue pathogenesis, this study examined the incidence of Chagas disease and T. cruzi/DENV coinfections in Machala, Ecuador. The sample set used for this study was collected as part of a larger dengue study in Machala by SUNY Upstate Medical University. The incidence of Chagas was 3.1% (n=360) and that of T. cruzi/DENV coinfections was 0.6%. The average age of Chagas positive individuals was 50 and 81.8% were female. As this study was a preliminary screening, a larger study should be undertaken in order to better access the T. cruzi/dengue situation in Machala and to further the knowledge base of the immune response to dengue via analysis of the effects of coinfections on disease progression