# Dangerous appetite: The impact of Trypanosoma cruzi infection on the feeding and defecation behaviors of Triatoma dimidiata sensu lato (Latreille, 1811)

## TL;DR

This study shows that T. cruzi infection makes the bug Triatoma dimidiata feed and defecate faster, which could increase the spread of Chagas disease.

## Contribution

The study reveals that T. cruzi infection alters the feeding and defecation behaviors of T. dimidiata to potentially enhance transmission.

## Key findings

- Infected bugs reached their host four times faster and defecated twice as quickly as uninfected ones.
- A higher proportion of infected bugs defecated during feeding and within 10 minutes of starting to feed.
- Infected bugs consumed more blood and fed at a faster rate than uninfected bugs.

## Abstract

Trypanosoma cruzi, the causative agent of Chagas disease, is primarily transmitted through the infected feces of blood-sucking bugs known as triatomines. As a result, its transmission is closely linked to the feeding and defecation behaviors of these insects. T. cruzi can alter various physiological processes in its vectors, including those involved in parasite acquisition, development, and excretion. This study aimed to assess the feeding and defecation behaviors of Triatoma dimidiata sensu lato (Latreille,1811), one of the main vectors, in relation to its T. cruzi infection status.

Using both T. cruzi-infected and uninfected T. dimidiata, we measured various variables related to feeding and defecation behaviors. Notably, infected insects reached their host four times faster and began defecating twice as quickly as uninfected ones (282 ± 58 s vs. 1132 ± 198 s; 580 ± 120 s vs. 1220 ± 166 s, respectively), and these differences were significant. Among the bugs that defecated, 89% (16/18) of infected insects and 70% (14/20) of uninfected insects defecated during feeding. Moreover, among the bugs that defecated, a significantly higher proportion of infected insects defecated within the first 10 minutes after the start of feeding (11/18 = 61%) compared to uninfected insects, in which this behavior was less frequent (5/20 = 25%) and occurred later. Additionally, infected insects presented a significantly greater blood meal intake and feeding rate.

Overall, these findings suggest that T. cruzi alters the feeding and defecation behaviors of T. dimidiata in a way that could enhance its transmission potential.

Chagas disease is a major public health concern in Latin America. It is caused by the parasite Trypanosoma cruzi, which is primarily transmitted when infected triatomine bugs defecate during or shortly after feeding on a host, depositing the parasite-laden feces on the host’s skin. The parasite can then enter the host’s organism through mucous membranes or skin lesions. This kind of transmission is known as stectorarian transmission. As such, certain aspects of feeding and defecation behaviors of triatomines, such as the elapsed time between the start of feeding and the start of defecation, play a crucial role in transmission. A vector that defecates on the host during or immediately after feeding increases the likelihood of parasite deposition on the skin, facilitating infection, compared to a vector that defecates after it left the vicinity of the host. Additionally, it is well known that some pathogens can manipulate their vectors by modifying various of their behaviors to enhance transmission likelihood. In this study, we investigated whether T. cruzi infection influences the feeding and defecation behaviors of Triatoma dimidiata, the major vector of Chagas disease in Southeastern Mexico, in a way that could enhance its transmission potential. Our results show that infected bugs detect their feeding host more quickly, feed more efficiently, and defecate sooner than uninfected bugs. These behavioral changes may enhance parasite transmission, suggesting a potential case of parasite-driven manipulation. Understanding these effects could help refine vector control strategies and improve Chagas disease prevention efforts.