INTRODUCTION

Chagas disease (CD), also known as American Trypanosomiasis, is an acute and chronic infectious condition caused by the protozoan Trypanosoma cruzi^1,2. This illness is endemic in low-income populations in the Americas^3,4 and is considered the fourth most prevalent parasitic disease worldwide, with approximately 300,000 new cases reported annually⁵.

The infection presents various transmission mechanisms, including the vectorial route^6,7, oral^6,8,9, maternal-fetal, blood transfusion, organ transplantation, laboratory accidents^1,2,10,11, and even the sexual route^10,11.

The vectors of CD are hematophagous hemipteran insects, belonging to the family Reduviidae and subfamily Triatominae¹², predominantly found in regions with tropical and subtropical climates, comprising 159 species (including five fossils) described^13-20.

Of the more than 30 species of hematophagous insects present in the Amazon, 22 occur in the Brazilian Amazon^21,22. In the state of Amazonas, 13 species are described^23-26.

In the state of Amazonas, the form of transmission that has generated the largest number of cases, with great epidemiological and social impact, is oral, directly related to the consumption of traditional drinks such as açaí (Eutherpe oleraceae; E. precatoria) and patoá (Oenocarpus bataua)²⁷. The first outbreak of the disease by oral transmission was recorded in 2004, in nine people in the municipality of Tefé, after consumption of contaminated açaí²⁸. In the last two decades, numerous acute cases related to oral transmission have been recorded, with six outbreaks in the state of Amazonas^29-33.

Because it is a disease mainly transmitted by vectors and has a wide geographical distribution³⁴, knowledge of the diversity of triatomines occurring in a region is importance for disease prophylaxis, as these insects are the “link” of this illness³⁵. Thus, providing monitoring of these vectors and improving the information system for the community regarding the prevention of CD may eventually decrease the transmission of the infection³⁶.

One of the strategies used to monitor a population is the application of questionnaires to assess people’s knowledge and perception, providing a view of the current situation of health surveillance and local knowledge, which is a cheap and effective strategy. The present study aimed to describe the knowledge of residents of the city of Guajará, AM, Brazil, about Chagas disease and its vectors.

METHODS

The research was conducted in the municipality of Guajará, located in the interior of the state of Amazonas and belonging to the Northern Region of Brazil. It has a territorial area of a little over 7,583.534 km², is located on the left bank of the Juruá River and is approximately 1,600 kilometers in a straight line from Manaus, the capital of the state³⁷.

Data collection took place from May to July 2023. The data collection instrument used was a semi-structured form containing both objective and subjective questions, aiming to gather information about the population characteristics (age, sex, skin color, education level, and estimated monthly income), as well as questions about the “Triatomine” insect (correct identification of them); actions taken when encountering the insect; whether they identify such insect as a potential disease transmitter; knowledge about Chagas disease (signs, symptoms, transmission methods, and prevention).

During the interview, participants were shown a board containing color photographs of 10 insects to assess whether they correctly recognized the triatomines (supplementary material 1). The exemplified groups are insects that are usually confused with triatomines. Letters A, B, and C are beetles, D and I are predatory bugs, E and J are plant-feeding bugs, and F, G, and H are triatomines.

Supplementary Material 1 : Examples of insects used for the identification of Triatomines. Photos: Jader Oliveira 

The form was applied to residents in urban areas, with one participant per household. The approach was through home visits, where researchers went to the household (randomly selected by convenience sampling), and the individual (over 18 years old) present in the residence was invited to participate.

The sample size calculation was based on the number of inhabitants of the municipality (which, according to the Brazilian Institute of Geography and Statistics (IBGE), is 17,193 inhabitants)³⁷, with a confidence level of 95% and a margin of error of 5%, resulting in a sample composed of 376 individuals.

In multiple-choice questions, the frequency of response for each statement was evaluated. To compare the frequency of categories, the Chi-square test was adopted, using IBM SPSS Statistics²⁵ software. In questions where there were response categories with a value of zero, the test could not be employed. The analyses were performed considering gender, type of housing, and level of education.

This work followed the ethical terms agreed in Resolution nº 466/12 and Resolution nº 510/16 and was subject to the approval of the Research Ethics Committee (CEP) of the Federal University of Acre - UFAC, for the research to be carried out, as it involved human beings. The collection was carried out after approval by the Research Ethics Committee - CEP (CAAE: 66209422.3.0000.5010).

RESULTS

Most of the interviewees were female, aged 27 to 35, of mixed race, and native to Guajará - Amazonas, followed by Cruzeiro do Sul - Acre. The majority reside in mixed residences (masonry and wood) and have completed high school. Regarding occupation, the majority were public servants, followed by homemakers and self-employed individuals, with a monthly income mainly ranging from 1 to 3 minimum wages (table 1).

Regarding knowledge about vectors (table 2), 80.75% of the interviewees reported having heard about triatomines, with the main sources of knowledge being mentioned as Radio/TV/Internet, community, and educational institution/school/technical course. It is worth mentioning that this question could have multiple options marked, so an individual could have heard about the insect on the radio, but also in a healthcare facility, for example.

Statistical analysis showed that there are more men who have heard about the insect (p=0.003). The test also revealed significance between the level of education and having heard about the vector at some point in life (p=0.001), with those who had completed/incomplete high school and completed higher education standing out.

Among the interviewees, 3.25% reported finding triatomines inside the home and 5.25% in the peridomicile, with no relationship found between the type of housing and encountering the suspected insect inside the home (p=0.496).

The places where triatomines were found inside the homes were: living room, balcony, kitchen, bedroom, laundry area, and entrance of the house. It’s worth noting that one individual reported two encounters in their home, one in the kitchen and another at the entrance. As for the peridomicile, they were found near dense vegetation, acai bunch, vegetables, buriti bunch, and on the ground near an acai tree.

Regarding the actions taken after encountering the vector, the majority reported killing the insect (65.38%). It’s important to mention that for this specific topic, the individuals who mentioned encountering the insects both inside the home and in the peridomicile were not summed up, as 8 individuals found the suspected insects in both locations and took the same action; thus, the action couldn’t be counted twice.

Interviewees were asked if they knew where to send a suspected insect if found inside or outside the home. The majority (91.25%) didn’t know where the triatomine should be sent. Among those who answered affirmatively, knowing where to send the triatomine, the following responses were given: Health Unit, Health Surveillance Foundation, sanitary surveillance, educational and research institutions, and Municipal Health Secretaria, but none mentioned taking actions to bring a suspected insect to the appropriate institutions.

Regarding the action taken upon finding a triatomine, as well as knowledge of where the insect should be taken, the test showed no significance between men and women.

Regarding fear of the vector, 52.25% responded no and 47.75% responded yes, mentioning the following reasons: causes diseases, can kill, bites humans, dangerous, venomous, frightening, contaminates acai, attacks the heart, and causes spots/wounds.

The survey inquired whether participants had experienced a bite from a suspected triatomine insect. About 2.5% confirmed having been bitten themselves, while 3% reported knowing someone who had encountered such bites, including friends, acquaintances, and family members like cousins and aunts.

Regarding preventative measures at home, 32% of respondents acknowledged taking action. Their strategies included maintaining cleanliness within the home and surrounding areas, employing insecticides, repellents, or incense, and ensuring the house remained closed during the night.

Individuals were asked if they knew if triatomines transmit any diseases, with the majority (81%) responding yes and mentioning the following names: Chagas disease, “barbeiro” disease, acai disease, heart problems disease, dengue, malaria, disease presenting lumps/wounds/itching on the body, and corona.

For the question about the identification of triatomines (table 3), the results showed that only 40.25% of individuals correctly identified the triatomines, with 22.75% choosing R. montenegrensis, followed by 10.5% E. mucronatus and 7% P. geniculatus. Regarding those who answered incorrectly, the majority chose a type of bug, with 23% choosing a predatory bug and 8.5% choosing a plant-eating bug.

Regarding the knowledge block about Chagas disease (Table 4), participants were asked if they knew someone who has or had Chagas disease, where 10% responded yes, mainly mentioning friends/acquaintances and family members.

They were also asked if they knew what health problems/situations Chagas disease could cause in humans, where 29.75% responded yes. Among these, many gave responses associated with clinical manifestations of Chagas disease (such as heart problems, tachycardia, cardiomegaly, megacolon, and Romaña’s sign), but a large number of responses were not associated with the disease, and some are also associated with other diseases in the region like malaria, making it difficult to assess the population’s knowledge regarding this question.

Regarding those who answered correctly, it was found that having completed higher education significantly influenced (p=0.002) compared to other groups.

Participants were asked if they knew if Chagas disease is curable, with the majority responding yes (58%), 21% said the disease is incurable, and 21% could not answer this question.

The interviewees were asked if they knew how Chagas disease (CD) is transmitted, where only 47.25% responded affirmatively and described the transmission process. In this study, no alternatives were suggested to the interviewees; their responses were transcribed as mentioned by them and grouped into similar answers. Additionally, for this question, participants could provide more than one response.

The study revealed that insect bites were the most suggested mode of transmission by the interviewees. A good representation of transmission through triatomine feces/urine and ingestion of contaminated food was also obtained, mentioned by some of the participants.

Regarding knowledge of how to prevent CD, 30.5% responded positively. The majority listed environmental cleanliness and food hygiene as ways to prevent the disease.

Participants were asked if they had ever engaged in any educational activities related to CD at any point in their lives, with 93% responding that they had never participated in such educational activities.

Regarding dietary habits (data not presented in a table), it was reported that 93% consume acai (Euterpe oleracea), 88.75% consume buriti (Mauritia flexuosa), 65.5% consume sugar cane (Saccharum sp.), 50.5% consume bacaba (Oenocarpus bacaba), 50.25% consume patoá (Oenocarpus bataua), and 75.75% reported consuming game meat. It is worth mentioning that for this question, individuals could indicate more than one option, so the same individual could report consuming all the foods in question.

Individuals who reported consuming game meat were asked about the type and preparation of game consumed. Regarding the type of game, various animals were mentioned, including paca (Cuniculus paca), collared peccary (Tayassu pecari), white-lipped peccary (Tayassu tajacu), armadillo (Dasypus spp. and Priodontes maximus), deer (Mazama spp.), capybara (Hydrochoerus hydrochaeris), monkey (Cebus sp.) agouti (Dasyprocta spp.), tapir (Tapirus terrestris), quatipuru (Urosciurus sp.), quati (Nasua sp.), jaguar (Panthera onca and Puma concolor), turtle (Chelonoidis sp.), caiman jacaré (Caiman sp. Melanosuchus sp.), tinamou (Crypturellus sp.), guan (Penelope sp.), mutum (Pauxi sp.), curassow (Aburria sp.), stingray (Potamotrygon sp.) and electric eel (Electrophorus sp.). Regarding the type of preparation, the most commonly cited methods were boiled, roasted, and fried.

They were also asked about the use of mosquito nets/curtains, with the majority (60.25%) stating that they use these devices.

DISCUSSION

The majority of respondents having heard about Triatomines is considered a positive point, and the way they received this knowledge resembles other studies, where television³⁸, school, and local media were mentioned as the main sources of knowledge acquisition³⁹. This demonstrates the role of educational institutions and journalism in knowledge acquisition.

Some authors mention that the sustainability of actions for prevention and control of Chagas disease (CD) necessarily depends on information and participation of the population, however, the Ministry of Health, as well as State Health Departments, do not have well-structured and active teams in the educational field, and there are also no structured actions in formal education prioritizing educational activities related to these diseases^38,40. This was also observed in the present study, where there was little involvement of health units and health professionals in the daily service regarding the topic.

The percentage of people finding Triatomines inside their homes, approximately 3%, is much lower than those found in other states such as Rio Grande do Sul with 31.8%³⁸, Minas Gerais with 43.28%⁴¹, and Bahia with 35.5%⁴². The states of Minas Gerais, Rio Grande do Sul, and Bahia are states where domiciliation and vector transmission of Chagas disease (CD) occur, which explains the observed percentage of Triatomines in households^42-45.

Rosenthal et al.³⁸ described an association with variables such as living or having lived in houses made of mud, adobe, or clay as a significant factor for encountering vectors, and living in masonry houses as a protective factor, unlike the present study where no such relationship with the type of housing was observed.

Regarding what to do when encountering a Triatomine, one of the worst attitudes is killing the insect (the most common response obtained in the present study), as this increases the possibility of direct contact with feces, urine, and hemolymph, consequently increasing the risk of contamination.

Other studies have also shown that killing the insect is one of the main attitudes of people and have indicated that this practice hinders surveillance efforts because the insects should be sent alive for parasitological examinations, and this information should be communicated to residents by Endemic Disease Control Agents (ACE), who should guide them on safety procedures when collecting these insects^40,46.

Villela et al.⁴⁰ also mentioned that some residents collected the insect in a container, a behavior that was not evidenced in the present study. This author also revealed that the majority of respondents either took the insects to Triatomine Information Posts (TIP) or handed them to an agent of the Chagas Disease Control Program (CDCP). Similar to what was described by Dias et al.⁴¹, where the most indicated locations by respondents were health services and schools, which in rural areas often function as TIPs.

Novais et al.⁴² described in their study that although the municipality had TIPs, none of the interviewees mentioned this support point, thus demonstrating the inadequacy in the dissemination and information of this service, which is not provided by the state of Amazonas and its municipalities.

The lack of information among residents about the correct procedure for collecting and the proper destination of captured Triatomines in households may be related to the absence or misinformation about the Chagas disease control servicee⁴². Such observations prompt reflection on the need for greater dissemination about the correct handling of insects, which is essential to feed the system, thus reducing cases of underreporting of Triatomines and Chagas disease in the municipality⁴¹. It is worth mentioning that in conversations with professionals working at the Health Surveillance Foundation of the municipality of Guajará, they reported that there is no established flow for receiving suspected insects, nor are there specific posts for receiving them.

The number of respondents who reported being bitten by Triatomines themselves or knowing someone who has been bitten is lower than that reported by Dias et al.⁴¹, which was 25.04%. Nonetheless, the data from the present study is concerning because if indeed these approximately 3% of respondents were bitten by Triatomines, it is noteworthy, particularly considering the Amazon region, where there are few records of vector transmission cases47.

Diverse studies demonstrate that a significant portion of the studied population is aware that Triatomines transmit Chagas disease (CD), with percentages of 85%⁴⁶, 92%39, and 100%⁴². Although the respondents in the present study mentioned other diseases or, in the majority, couldn’t specify the name of the transmitted disease, this fact informs us that the study population recognizes the insect as a vector of some disease satisfactorily. However, health education actions regarding CD need to be strengthened in the focus municipality of the study to contribute to the effectiveness of entomological surveillance actions.

The species of Triatomines most recognized by the respondents belong to the genus Rhodnius, which has a broad geographic distribution in South and Central America⁴⁸. In Amazonas, there are records of six species of this genus: R. amazonicus⁴⁹, R. brethesi^50,51, R. montenegrensis²⁵, R. paraensis²³, R. pictipes^52,53, and R. robustus⁵³. Being the most representative genus for the state of Amazonas, this could explain the participants’ accuracy in identifying the species indicated as a Triatomine.

Regarding those who responded by indicating predatory and phytophagous bugs, this can also be seen as positive because it demonstrates that these people have some notion, given that these species have similar morphology to Triatomines.

Regarding knowing people with CD, studies in Minas Gerais and Brasilia revealed that 59.18% and 51.2% responded affirmatively^41,46. In both studies, friends and family members were reported among the groups of known individuals. The areas of the mentioned studies are considered areas of higher prevalence for CD; thus, it is expected that respondents know more people diagnosed with the disease, unlike what was observed in the present study.

Nearly 60% of the respondents stated that CD is curable, unlike other studies where the majority of respondents mentioned that there is no cure for CD^42,46.

The study revealed a deficit in knowledge among part of the population regarding the transmission of CD, but some demonstrated knowledge of transmission through contact with Triatomine feces/urine, as well as oral transmission.

Regarding how to prevent the disease and the entry of vectors into the residence, studies also reported cleanliness and organization of the environment as a preventive measure indicated by the respondents^40,41,46. Although such actions are also applicable to other vector-borne diseases or diseases transmitted by improperly handled food, this information holds significant value since if such actions are indeed executed, they have an important potential for prevention.

A majority of the respondents also reported using mosquito nets, contrary to what was evidenced by Novais et al.⁴², where only 25.8% of the studied population used this measure. The use of mosquito nets/curtains constitutes a preventive measure against vector transmission not only for Chagas disease (CD) but also for other vector-borne diseases such as malaria and dengue, for example. Although the population’s use of this item may not be specifically directed towards CD prevention, it has a positive impact on it.

Considering that Triatomines are nocturnal and people are unprotected during this period, studies demonstrate that the use of mosquito nets/curtains contributes to reducing contact with the vector, thus reducing the possibility of blood meals and consequently transmission⁵⁴.

Regarding the dietary habits of the respondents, it is important to highlight that the mentioned fruits do not pose a primary risk, but rather their inadequate preparation with serious hygienic, manufacturing, and conservation deficiencies⁵⁵. This statement is particularly important to avoid stigmatizing the production and/or consumption of foods that are important sources of calories and nutrients for the population that consumes them, as well as sources of work, income for regional gastronomy, and tourism in various areas⁵⁵.

In Brazil, the most common form of oral contamination reported by studies is through the ingestion of acai juice and sugarcane juice^56-58. Recent cases reported in Brazil of acute CD are related to the consumption of acai juice (the main food mentioned in the present study), considered an essential food in the diet of the population in the Northern region of Brazil and highly appreciated in other states and countries^59,60.

A study reported 19 occurrences of oral CD between 2009 and 2019, distributed among the states of Acre, Amapá, Amazonas, Pará, Maranhão, and Tocantins⁶¹. The study also revealed that the state with the highest number of cases was Pará, and the main contaminated food involved was artisanal acai, but there were also records of contamination through the ingestion of bacaba juice⁶¹.

Regarding the wild game meats consumed by the respondents, they are considered intermediate hosts of T. cruzi: paca, collared peccary, white-lipped peccary, armadillo, deer, agouti, tapir, capybara, monkey, agouti, and coati²³. A study revealed that although acquiring CD through the consumption of meat from infected animals is a rare event, it should always be considered as a transmission hypothesis, particularly when other routes are ruled out, since hunting, handling of carcasses, and consumption of wild mammals (reservoirs) are common among rural populations in Brazil and Latin America⁶².

CONCLUSION

The research revealed that the majority of the interviewees reported having heard of the vector at some point in their lives, with the main sources of knowledge being educational institutions and media outlets. There was little involvement from healthcare units and professionals in addressing the issue in their daily service.

Regarding transmission and preventive measures, knowledge among the study population is satisfactory for the most part, with over half using mosquito nets/curtains as a preventive measure. However, there was limited understanding of the signs and symptoms of the disease. Less than half of the interviewees correctly identified Triatomines, with R. montenegrensis being the most mentioned species as the vector.

Concerning dietary habits, the majority consume fruits considered risky for oral transmission of CD, and there is a relatively high consumption of game meat. Although some aspects were satisfactory, educational efforts need to be intensified to fill gaps and promote disease prevention.