TriatoDex, an electronic identification key to the Triatominae (Hemiptera: Reduviidae), vectors of Chagas disease: Development, description, and performance

Automated identification of Chagas disease vectors using AlexNet pre-trained convolutional neural networks

The 158 bug species that make up the subfamily Triatominae are the potential vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. Despite recent progress in developing a picture-based automated system for identification of triatomines, an extensive and diverse image database is required for a broadly useful automated application for identifying these vectors. We evaluated performance of a deep-learning network (AlexNet) for identifying triatomine species from a database of dorsal images of adult insects. We used a sample of photos of 6397 triatomines belonging to seven genera and 65 species from 27 countries. AlexNet had an accuracy of ~0.93 (95% confidence interval [CI], 0.91-0.94) for identifying triatomine species from pictures of varying resolutions. Highest specific accuracy was observed for 21 species in the genera Rhodnius and Panstrongylus. AlexNet performance improved to ~0.95 (95% CI, 0.93-0.96) when only the species with highest vectorial capacity were considered. These results show that AlexNet, when trained with a large, diverse, and well-structured picture set, exhibits excellent performance for identifying triatomine species. This study contributed to the development of an automated Chagas disease vector identification system.

Triatomines in the city: A study of Rhodnius neglectus in Jaboticabal, São Paulo, Brazil, and its epidemiological implications

BACKGROUND

Chagas disease, a significant global health concern rooted in social inequalities and political oversights, remains a challenging public health issue impacting millions worldwide. The increasing detection of triatomines, the vectors of Chagas disease, in urban areas complicates the situation.

METHODS

This study investigated the incidence of Rhodnius neglectus in the urban areas of Jaboticabal, São Paulo, Brazil, following several reports and previous collections of triatomines in the city. An educational approach was adopted, distributing informational materials and engaging the community through social networks to generate notifications that would enable the identification of triatomines. Specimens were collected using various methods, including passive surveillance actions, light traps, and active searches in palm trees.

RESULTS

Rhodnius neglectus was found in urban areas, invading homes in Jaboticabal, and was identified in palm trees. The educational approach led to the collection of 93 triatomines. Colonization was observed in a residence, with eggs, nymphs, and a concerning record of blood-feeding on a resident child. The houses where specimens were captured often had nearby palm trees with birds and nests, facilitating the passive transport of these insects and increasing the risk of invasion due to light attraction. No triatomines infected with Trypanosoma cruzi were identified.

CONCLUSIONS

These findings emphasize the need for preventive measures to reduce the prevalence of R. neglectus in urban environments. The data elucidate the occurrence of R. neglectus in the city of Jaboticabal, associated with its potential behavioral adaptation in urban environments, underscoring the need for innovative control strategies.

Trapping Triatominae Bugs Using Mice-Baited Traps along the Peninsula of Baja California, Mexico

During an exploratory fieldtrip along the peninsula of Baja California, Mexico, we used mice-baited traps in search of Triatominae, the vectors of Chagas disease. A total of 433 traps were set in five localities following a latitude gradient along the peninsula. Triatominae were caught in rocky ecotopes in two localities. The specimens were identified as Paratriatoma hirsuta in the first locality, and Dipetalogaster maxima in the second, in accordance with the reported distributions of these species. The overall trap success was 3.1%, with an average of 1.3 bugs per positive trap. In the site with most bugs collected, trap success was 26.8%. To the best of our knowledge, this is the first time that mice-baited traps have been used in this geographic area to collect Triatominae bugs. This short report confirms the usefulness of this trapping system when standardized protocols are needed.

Trypanosoma cruzi Parasite Burdens of Several Triatomine Species in Colombia

Trypanosoma cruzi, the causal agent of Chagas disease, is mainly transmitted by insects of the Triatominae subfamily. In Colombia, there are 26 triatomine species, and 16 of them are naturally infected with the parasite. The parasite loads of naturally infected vectors can be significant in targeting specific species that can affect the epidemiology of the disease. Studying their ecology and behavior is vital to understand their role in T. cruzi transmission dynamics. We evaluated the parasite loads of 182 field-collected triatomines corresponding to 10 species in 13 departments across Colombia. We standardized a methodology to quantify T. cruzi DNA in these insects. We obtained a LOD (limit of detection) of 3.05 p-eq/mL. The 82% of triatomines we evaluated were positive for T. cruzi infection, with loads ranging from hundreds to millions of equivalent parasites per milliliter. Panstrongylus geniculatus, Rhodnius prolixus, and Triatoma dimidiata were the species with the highest loads of T. cruzi; however, other species whose role as vectors is still unknown were also found with high loads of parasites. Our results suggest the relevance of secondary species for T. cruzi transmission in Colombia. We hope our data can help improve entomological surveillance and vector control programs in the country and the region.

Triatoma costalimai, a neglected vector of Trypanosoma cruzi in the Cerrado savannas of South America: A comprehensive review

Triatoma costalimai is a little-known triatomine-bug species whose role as a vector of Chagas disease remains poorly understood. To address this gap, we conducted a comprehensive review of the literature and assessed the evidence base from a public-health perspective. We found 89 individual documents/resources with information about T. costalimai. DNA-sequence and cytogenetic data indicate that T. costalimai belongs, together with Triatoma jatai, in a distinct clade within the 'pseudomaculata group' of South American Triatoma. Triatoma costalimai is probably a narrow endemic of the Cerrado on the upper Tocantins River Basin and associated ranges/plateaus; there, the species thrives in the sandstone/limestone outcrops typical of the "Cerrado rupestre" (rocky-soil savanna) and "mata seca decídua calcária" (limestone-soil dry forest) phytophysiognomies. Wild T. costalimai appear to feed on whatever vertebrates are available in rocky outcrops, with lizards and rodents being most common. There is persuasive evidence that house invasion/infestation by T. costalimai has increased in frequency since the 1990s. The bugs often carry Trypanosoma cruzi, often defecate while feeding, have high fecundity/fertility, and, under overtly favorable conditions, can produce two generations per year. Current knowledge suggests that T. costalimai can transmit human Chagas disease in the upper Tocantins Basin; control-surveillance systems should 'tag' the species as a potentially important local vector in the Brazilian states of Goiás and Tocantins. Further research is needed to clarify (i) the drivers and dynamics of house invasion, infestation, and reinfestation by T. costalimai and (ii) the genetic structuring and vector capacity of the species, including its wild and non-wild populations.

Coleção de Vetores de Tripanosomatídeos (Fiocruz/COLVET) held at the institution Fiocruz Minas in Brazil: diversity of Triatominae (Hemiptera, Reduviidae) and relevance for research, education, and entomological surveillance

The Coleção de Vetores de Tripanosomatídeos (Fiocruz/COLVET), Minas Gerais, Brazil, stands out as one of the most important collections of blood-sucking triatomines, the vectors of Trypanosomacruzi that causes Chagas disease. The aim is to describe the collection and the services it provides to support scientific research, educational activities, and entomological surveillance between 2013-2019.The data associated with the specimens held in Fiocruz/COLVET is available from the Sistema de Informação sobre a Biodiversidade Brasileira (SiBBr). These specimen metadata were analyzed and either tabulated or plotted on graph and maps. The records of services provided by the collection between 2013-2019 were also categorized and analyzed. There are 12,568 triatomine specimens deposited in the collection that belong to 77 species and 11 genera, from 15 American countries. Of the ~ 65 species of triatomines found in Brazil, 38 (57.6%) are present in the collection, including specimens from all biomes and all but three Brazilian states. The occurrence of Triatomacostalimai, Triatomalenti, Rhodniusnasutus, and Panstrongyluslenti apparently collected beyond their known distribution ranges are reported and discussed. The collection provided 168 services, supporting educational activities (41.7%), scientific research (35.7%), and regional/national entomological surveillance of triatomines (22.6%). Between the years 2014 and 2020, the number of biological specimens deposited in the Fiocruz/COLVET repository increased from 4,778 to 12,568 triatomine specimens. In addition to its great value to biodiversity conservation, the collection is of great importance because of its support of research and educational activities, and contributions to entomological surveillance, and, therefore, to public health.