1. Household Infestation Rates of Chagas Disease Vectors and Trypanosoma cruzi Prevalence in Southern Ecuador Stanton Jasicki Dr. Daniel Herman Dr. Mario Grijalva Sofía Ocaña Introduction Chagas disease affects an estimated 10 million people across its endemic regions in Central and South America (WHO, 2010). The disease is caused by the parasite Trypanosoma cruzi, and presents itself in two stages. The acute stage is marked by flu- like symptoms such as fever, headaches, and muscle pain. The chronic stage is when classic cardiac, digestive, and neurological disorders are observed. The most common vectors for transmission of T. cruzi, and thus Chagas disease, are members of the Triatominae subfamily. These beetles, collectively referred to as triatomines or commonly as kissing bugs, feed on vertebrate blood. Transmission of T. cruzi usually occurs when a triatomine bites an exposed area of skin and then defecates. The natural instinct to scratch a bite is all that is needed to allow the parasite present in the fecal matter to enter the body. Household rates of infestation are unknown in many rural areas of Chagas disease’s endemic areas. The purpose of this study was to detect the presence of triatomines within 13 rural communities of Loja Province in Ecuador as well as to determine the seropositivity for T. cruzi of residents within the communities. Methods Houses in each of the 13 communities were screened for the presence of triatomines. Screenings consisted of 2 individuals thoroughly examining the house and surroundings (chicken nests, woodpiles, bathrooms, etc.) for 30 minutes. If live triatomines were found, the home was considered infested. A total of 354 houses were searched. Screening for T. cruzi within the 13 communities was accomplished with the use of InBios and Stat-Pak rapid field tests, both of which are specific to antibodies produced to T. cruzi. Individuals whose blood reacted positively for either of the field tests were subjected to a second round of the same field tests. They were also were asked to give a blood sample so their serum could be tested with the same field tests for further confirmation Results Community First Stat-Pak Second Stat-Pak Stat-Pak Serum First InBios Second InBios InBios Serum JurupePositive Negative TuburoPositive Negative TuburoNegative Positive Negative TuburoPositive Negative TuburoNegative Positive Negative TunduramaPositive Negative Santa EsterPositiveNegativePositiveNegative Conclusions Of the 354 houses searched, 48 houses were found to be infested. Across the 13 communities, infestation indices ranged from 0- 32.1%, with an average infestation index of 13.56%. The highest infestation indices were seen in Tacoranga (32.1%), Coamine (25.0%), Jurupe (25.0%), Guara (24.0%), Chirimoyos (16.7%), and Chaquizhca (15.2%). Infestations were not observed in Galapagos and El Tingo. Of the total 949 individuals screened for Chagas disease using the rapid field tests, 7 positive results were obtained, corresponding to a prevalence of 0.74%. Positive field tests were obtained in Santa Ester, Jurupe, Tuburo, and Tundurama, with 4 out of 7 positive individuals residing in Tuburo. Reactive Stat-Pak field tests yielded negative results for InBios tests. Likewise, individuals who tested positive, using InBios, tested negative when using Stat-Pak. Left: Positive field tests. Right: Performing field tests. Table 2: Number of positive results obtained and prevalence by community and county. Table 3: Results from first, second and serum based field tests, as well as the community they were obtained from. Community County Individuals screened Positive results Prevalence (%) Ashimingo Paltas 6600 Coamine Paltas 8700 Tacoranga Paltas 6500 Santa Ester Gonzanamá 4312.33 Chirimoyos Gonzanamá 1100 Jurupe Gonzanamá 4812.08 Galapagos Quilanga 6500 Tuburo Quilanga 5547.27 Guara Calvas 6600 Chaquizcha Calvas 14200 Machay Espíndola 5500 Tundurama Espíndola 12910.78 El Tingo Espíndola 11700 Totals94970.74 Communities County Houses searched Infested houses Infestation index (%) Ashimingo Paltas 2015 Coamine Paltas 401025 Tacoranga Paltas 28932.1 Santa Ester Gonzanamá 1616.3 Chirimoyos Gonzanamá 6116.7 Jurupe Gonzanamá 28725 Galapagos Quilanga 2800 Tuburo Quilanga 3026.7 Guara Calvas 25624 Chaquizcha Calvas 33515.2 Machay Espíndola 2613.8 Tundurama Espíndola 5459.3 El Tingo Espíndola 2000 Totals3544813.56 Table 1: Total number houses searched and number of infested houses by community and county. Infestation indices are also given for each community. Left: Trypanosoma cruzi life-cycle. Right: Triatomine. Acknowledgments Special thanks to Dr. Daniel Herman, Dr. Mario Grijalva, Sofía Ocaña, and the Tropical Disease Institute of Ohio University. Also, thanks to the Office of Research and Sponsored Programs for providing funding. References Centers for Disease Control and Prevention. (2009). Trypanosomiasis, American. Retrieved October 17, 2010, from http://www.dpd.cdc.gov/dpdx/HTML/TrypanosomiasisAmerican.ht m. World Health Organization. (2010). Chagas disease (American trypanosomiasis). Retrieved October 15, 2010, from http://www.who.int/mediacentre/factsheets/fs340/en/index.html.