Identification of Trypanosoma cruzi lineages in Triatoma dimidiata (Hemiptera: Reduviidae), the vector of Chagas disease in Yucatán, México

Abstract Chagas disease is caused by Trypanosoma cruzi , a parasite with seven lineages, or discrete typing units (DTUs). Six of these lineages (DTU‐I to DTU‐VI) can cause acute or chronic clinical symptoms in humans infected with the parasite. Triatoma dimidiata sensu lato (Latreille, 1811) is the main vector of T. cruzi in Yucatán State, México. Epidemiologically, it is important to determine the most prevalent lineages in this vector. Between April 2022 and May 2023, we examined 231 T. dimidiata adults from 10 municipalities using microscopy to detect trypanosomatids, real‐time PCR to detect T. cruzi and multilocus conventional PCR to identify DTU. In three municipalities, 94.81% (219/231) of triatomines were tested, with most coming from Tixkokob ( n = 146), Mérida ( n = 46) and Muna ( n = 27). Overall T. cruzi prevalence was 33.33% (77/231), with Mérida having the highest prevalence at 54.35%, followed by Tixkokob at 26.71%. We identified T. cruzi lineages in 29.87% (23/77) of infected T. dimidiata . These included TcI ( n = 7), TcIII ( n = 7) and TcIV ( n = 5), as well as mixed TcI/TcIII ( n = 2) and TcI/TcIV ( n = 2) infections. In addition to the previously documented lineages (TcI, TcII, TcV and TcVI), we report the TcIII and TcIV lineages for the first time in T. dimidiata from Yucatán. TcIV had been reported in the spider monkey Ateles geoffroyi , but not in T. dimidiata . These findings confirm that Yucatán is an endemic area for Chagas disease, as all six T. cruzi lineages are present, and they underscore the need to strengthen prevention measures and control of the vector T. dimidiata .