INTRODUCTION

A total of 156 species of triatomines, vectors of Chagas disease, are known.^1-2 In Brazil, triatomines are known by the most different names: bicudo, chupa-pinto, bicho-de-parede preto, fincão, chupão, barbeiro, chupança, percevejão, percevejo-do-sertão, procotó, baratão, piolho-de-piaçava, bruxa, quiche do sertão, prorocotó, rondão vunvun, cascudo, percevejo gaudeiro, percevejo francês and percevejo grande.^3-5

The northeast caatinga is a region where there are a large number of these insects. They are insects of the Hemiptera, hematophagous order and the main transmitter of Chagas disease. Triatomines must feed on blood, they inhabit both wild environments and peridomiciles and homes⁶. They are found in cracks in the walls, in stables, pigsties, chicken coops, dovecotes, tree hollows and boulders.

The domiciliation process occurs when these insects leave their natural habitat due to destruction or modification and end up migrating to homes where domestic animals are raised, in the peridomicile, with precarious structures providing a source of shelter for the insect. Thus, this process directly influences the occurrence and transmission of Trypanosoma cruzi, the etiological agent of Chagas disease.^7-8

Chagas disease has been known for over 100 years, as it was described by Carlos Chagas in 1909. Even so, it is still considered a neglected disease, which victimizes millions of Brazilians⁶.

Studies on triatomine infestation at home have been conducted, including the assessment of the occurrence in household environments in the city of Aurora, Ceara, between 2012 and 2015;⁹ geographic distribution, household infestation and natural infection of triatomines in the state of Piaui, Brazil, 2008;¹⁰ home infestation by triatoma infestans and some epidemiological aspects of American trypanosomiasis in an area of the state of Sao Paulo, Brazil;¹¹ triatoma infestans in an area under entomological surveillance for Chagas disease, state of Sao Paulo, Brazil;¹² occurrence of triatomines in intra and peridomiciliary environments in the city of Campos Sales, Ceara,¹³ among other studies.

In the state of Ceara, between 2015 and 2019, about 28% (51) of the cities had triatomine infestation greater than 5%. This percentage of triatomine infestation is considered high. What draws attention is the dispersion of these cities throughout the state, showing the wide distribution of triatomines in the state, which in the same period, recorded 557 positive triatomines for T. cruzi in an indoor environment and about 3.4% of natural infection (557/16365), distributed in 66 (36%) of the cities.¹⁴

In 2013, a total of 1218 cases of CD were cataloged in people over 15 years old in the state of Ceara, and 22 cases (~1.7%) of this record were confirmed in the city of Taua⁶. The city has numerous locations with the presence of triatomines, which justifies the study. There is still insufficient information on the processes of triatomine domiciliation. Therefore, this study aimed to carry out an analysis of the infestation of triatomines in the countryside of Taua-Ce, in 2012.

METHODS

The survey was carried out in the city of Taua-Ce, in 2020. It is a descriptive/exploratory study of a quantitative nature, where secondary data were obtained from the Health Department (Endemic Nucleus) of the city, having as object of study the occurrence of triatomines in households in the city.

The city of Taua is located in the State of Ceara, northeast of Brazil, located in the Inhamuns Region. The city is located at a distance of approximately 357 km from the capital Fortaleza, with the geographical coordinates: latitude: 06º00'11"S, longitude: 40º17'34"W, altitude 402.7m, with an area of 4011 km², with a total of 59062 inhabitants. It has a hot, semi-arid tropical climate, with rains from February to April, with open shrubby caatinga vegetation and thorny deciduous forest with an average rainfall of 416.9 mm.^15-16

Since 1995, the city has been made up of 8 districts, including the district of Taua (Headquarters), Barra Nova, Carrapateiras, Inhamuns, Marrecas, Marruas, Santa Teresa and Trici.¹⁵

The city borders on the north with Pedra Branca and Independencia, on the south with Parambu and Arneiroz, on the east with Mombasa and Pedra Branca and on the west with Quiterianopolis and Parambu.¹⁶ (Figure 1)

Secondary data were obtained in January 2020 from the Health Department (Endemic Nucleus). The endemics nucleus is responsible for the surveillance of triatomines of the Chagas Disease Control Program (CDCPh).

As an inclusion criterion in the study, data collected from 06/05/2012 to 09/26/2012 in fifteen areas of the countryside of the city were selected and, as an exclusion criterion, the houses in which there was nobody at the time of the visit of the Endemic Combat Agents (ECAs).

The triatomines are captured in visits programmed during the PCDCh, by the ECAs of the center of endemic diseases of the city. A field visit was carried out along with the ECAs to capture the insects (triatomines).

The captured insects are placed in a container (five insects in each jar), with a label identifying the type of indoor environment (inside the house) or peridomiciliary environment (yard) and later taken to the Entomology Laboratory of Taua (LEM), where insect identification and parasitological analysis are carried out.¹⁷

The procedures for capturing and conserving live specimens follow the norms of the Manual of technical norms of the Chagas disease control campaign.¹⁷

In order to carry out intra and peridomiciliary capture, the following field materials were needed: bag, flashlight, large tweezers, batteries, containers to store the samples, GPS device, gloves, labels, manual sprayer, dislodging product for triatomines and a field sheet according to the Manual of technical standards.^17-18

Data were analyzed by descriptive statistical techniques using Excel Office 2013® software and presented in the form of absolute numbers, relative frequency (infestation index) and average percentage.

This study complies with the ethical principles of Resolution 466/12 of the National Health Council. The data used in this study do not address nominal data of the residents or any other that establish their identification. Thus, submission to the Research Ethics Committee (REC) was not necessary, according to Resolution No. 510 of the National Health Council, of April 7, 2016.¹⁹

RESULTS

Figure 2 shows the triatomine infestation rate in the locations: Sítio Central do Incra 50%, Fazenda Brôco 18.2%, Jordão 16.7%, Fazenda Bom Lugar 0%, Fazenda Riacho do Mato 40%, Fazenda Cearauai 37, 5%, Sítio Riacho do Mato 30%, Fazenda Cedro 17.4%, Cachoeirinha 27%, Fazenda Várzea do Feijão 24%, Cachoeira do Júlio 41.2%, Fazenda Mutuquinha 9.4%, Sítio Várzea Grande 33.3%, Iparana 9.1% and Cachoeira do Celso 16.7%. The average percentage of triatomine infestation was ≅24.7%.

In the analyzed period, a total of 15 locations with 732 residents were surveyed. Of these, only one home was not found to have triatomines. Of the 386 houses visited, 333 (86.3%) were evaluated, with 87 (26.1%) houses being positive for triatomines and 53 (13.7%) houses were not surveyed, as there was nobody in the house in the moment of the PCDCh campaign. (Table 1).

A total of 21 triatomines (Triatoma infestans) were captured during the field research carried out along with the ECAs and sent to the LEM for identification and parasitological analysis of the insects. Spraying was performed in all homes where the insects were found using the alpha-cypermethrin-based insecticide (ALFATEK 200 SC).

DISCUSSION

The triatomine infestation rate analyzed in this study was 26.1%. The value is compatible with that found by Candido and Collaborators in Campos Sales (CE), which was 20.4%. However, it differs greatly from the results found by Pinto and Collaborators in Aurora (CE), which was 80.97%.^9-13 Therefore, despite the low infestation rate found in Taua (CE), it can be observed in this work that there are areas of up to 50% infestation in the city, forming colonies of triatomines may occur in households and annexes, indicating considerable rates of infection by Trypanosoma cruzi.¹⁸

The invasion by triatomines inside homes and annexes is worrying, since these insects are potential sources of natural infection. In addition, it expresses the housing conditions that the populations live, in which the domicile of these insects took place.^9-13-18

It is also believed that this invasion of triatomines in homes is linked to the occurrence and transmission of the parasite, in addition to connecting the wild and domestic cycles of Chagas disease.^{8-13-18-20-22}

It is concluded that there is home colonization by triatomines in the city of Taua. Therefore, improvements are necessary in the epidemiological surveillance of the city and the adoption of prophylactic measures by the residents, such as: always keeping the house and surroundings clean, as well as the use of mosquito nets, protection screens on doors and windows, as well as educational work by authorities focused on the prevention of Chagas disease, aiming to raise awareness of the vector of the disease and its main shelters as a way of minimizing the risks to which they are exposed. In addition, a more frequent entomological control is suggested, going beyond the period of the campaigns for a better monitoring of the occurrence of these insects.

REFERENCES

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