Kissing bug on map of Latin America

Chagas Disease: Are We Winning the War Against the Kissing Bug?

Jordan Keane in Health & Wellness August 2025 • 4 min read.

"New research sheds light on insecticide resistance in Triatoma sordida, a key vector of Chagas disease, and what it means for disease control."

Chagas disease, a potentially life-threatening illness caused by the parasite Trypanosoma cruzi, affects millions worldwide, particularly in Latin America. The disease is primarily transmitted through 'kissing bugs' (triatomines), which become infected by feeding on infected animals or people. Control efforts largely rely on insecticides to reduce bug populations, but insecticide resistance poses a significant threat.

One of the primary vectors of Chagas disease, Triatoma sordida, has shown resistance to commonly used insecticides. Understanding the extent and impact of this resistance is crucial for designing effective control strategies. While laboratory tests can indicate resistance, their real-world impact needs confirmation through field studies.

Recent research published in the Revista da Sociedade Brasileira de Medicina Tropical investigates the susceptibility of Triatoma sordida to alpha-cypermethrin, a pyrethroid insecticide, under natural climatic conditions. This study bridges the gap between laboratory findings and field effectiveness, providing valuable insights for vector control programs.

The Insecticide Resistance Puzzle: What Does It Mean in the Field?

Insecticide resistance occurs when a population of insects develops the ability to tolerate doses of insecticide that would normally be lethal. This phenomenon arises due to genetic variability within the population and is exacerbated by continuous exposure to insecticides, which creates a selection pressure favoring resistant individuals.

Until recently, insecticide resistance in triatomines was not considered a major threat. However, studies have shown that resistance is more widespread than previously thought. This highlights the urgent need for characterization and careful monitoring of resistance patterns.

High resistance ratios (RR50 > 50) have been reported in Triatoma infestans populations in Bolivia and Argentina.
Studies in Venezuela, Colombia, and Paraguay focus on vector control of Rhodnius prolixus, Triatoma infestans, and other species.
In Brazil, research is increasing on Triatoma brasiliensis, Triatoma sordida, and other species collected from areas with persistent infestations (RR50<8).

Two main criteria guide the interpretation of resistance ratios. According to Zerba & Picollo, populations with an RR50 > 2 are considered resistant, while the Pan-American Health Organization (PAHO) considers populations with an RR50 ≥ 5 as resistant. Based on these classifications, researchers propose investigating operational failures in vector control, replacing insecticides with different modes of action, and conducting ongoing susceptibility monitoring.

Looking Ahead: The Future of Chagas Disease Control

While this study indicates that the tested populations of Triatoma sordida remain susceptible to alpha-cypermethrin in the field, it also underscores the complexity of insecticide resistance. Continuous monitoring and adaptive strategies are essential for effective Chagas disease control. Future research should focus on integrating laboratory and field bioassays, exploring alternative control methods, and addressing socioeconomic factors that contribute to disease transmission to safeguard vulnerable communities.

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Everything You Need To Know

What is Chagas disease, and how is it primarily transmitted?

Chagas disease is a potentially life-threatening illness caused by the parasite Trypanosoma cruzi. It is primarily transmitted through 'kissing bugs' (triatomines). These bugs become infected by feeding on infected animals or people and then transmit the parasite when they feed on another host. The disease is prevalent in Latin America and affects millions worldwide.

Why is insecticide resistance in Triatoma sordida a concern, and what are the implications?

Insecticide resistance in Triatoma sordida, a key vector of Chagas disease, is a significant concern because it threatens the effectiveness of control efforts. Triatoma sordida has shown resistance to commonly used insecticides like alpha-cypermethrin. This resistance can lead to increased bug populations, potentially increasing disease transmission rates. The implications include the need for characterization and careful monitoring of resistance patterns, the investigation of operational failures in vector control, and the exploration of alternative control methods.

How is insecticide resistance determined, and what resistance levels are considered significant?

Insecticide resistance is determined through laboratory tests and field studies. Researchers measure the susceptibility of insect populations to insecticides. Resistance ratios (RR50) are used to quantify resistance levels. According to Zerba & Picollo, populations with an RR50 > 2 are considered resistant. The Pan-American Health Organization (PAHO) considers populations with an RR50 ≥ 5 as resistant. These criteria guide the interpretation of resistance patterns, helping researchers understand the impact of insecticide resistance in different triatomine species, such as Triatoma infestans, Rhodnius prolixus, Triatoma brasiliensis, and Triatoma sordida.

What are some of the strategies to combat Chagas disease, and why are field studies important?

Strategies to combat Chagas disease include using insecticides to reduce bug populations. Field studies are crucial because they bridge the gap between laboratory findings and real-world effectiveness. The recent research published in the Revista da Sociedade Brasileira de Medicina Tropical investigates the susceptibility of Triatoma sordida to alpha-cypermethrin under natural climatic conditions. Understanding the real-world impact of insecticide resistance is essential for designing effective control strategies. Additionally, investigating operational failures in vector control, replacing insecticides with different modes of action, and conducting ongoing susceptibility monitoring are important.

What are the future directions for Chagas disease control, and what factors need to be addressed?

Future research should focus on integrating laboratory and field bioassays, exploring alternative control methods, and addressing socioeconomic factors that contribute to disease transmission. Continuous monitoring and adaptive strategies are essential for effective Chagas disease control. Understanding the complexities of insecticide resistance in vectors like Triatoma sordida is crucial. Replacing insecticides with different modes of action, conducting ongoing susceptibility monitoring, and addressing socioeconomic factors are important steps for safeguarding vulnerable communities.