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# Triatomines (Rhodnius prolixus, Triatoma dimidiata)

- Parasite
- Exam priority: medium

Bugs that live in cracks of mud-walled houses and palm-thatch roofs. They bite at night and spread Chagas in their faeces.

Updated 2026-11-01

Also called: kissing bug, pito (Colombia), chipo

## Key points

- Transmits T. cruzi in its faeces, not its saliva.
- Incomplete metamorphosis: egg, five nymphal stages and adult; all bite.
- In Colombia, R. prolixus is the main household vector; T. dimidiata is second in importance.
- Control: better housing + residual spraying + community surveillance; there is no vaccine.

## At a glance

**Shape**
Elongated bug with a cone-shaped head, a straight proboscis folded under the head and spotted abdominal edges

**Family**
Reduviidae, subfamily Triatominae

**Type**
Blood-feeding hemipteran insect (vector)

**Size**
Adults from one to several centimetres, depending on species

## Morphology

- Elongated head with a straight three-segmented proboscis folded under the body.
- Wings cover the abdomen in adults; nymphs are wingless.
- All five nymphal stages and adults of both sexes feed on blood.

## Transmission

- Biting at night, it defecates near the wound; Trypanosoma cruzi leaves in the faeces and enters when the person scratches, or through the conjunctiva and mouth.
- Bug faeces contaminate juices and food and cause outbreaks of oral Chagas.
- Rhodnius also passes Trypanosoma rangeli in its saliva, without causing disease.

**Reservoir:** Opossums, rodents, dogs and other domestic and wild mammals; Humans

**Vector:** In Colombia, Rhodnius prolixus is the main household vector; Triatoma dimidiata, T. venosa, T. maculata and Panstrongylus geniculatus also matter.

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Life cycle

- The female lays eggs in cracks in walls, roofs, nests or palms.
- A wingless nymph hatches and already feeds on blood.
- It passes through five nymphal stages; each moult needs at least one blood meal.
- After the fifth moult the winged adult appears (incomplete metamorphosis, no pupa).
- The full cycle takes months; it hides by day and comes out at night to feed.

## Virulence factors

- Every stage bites and can become infected and transmit.
- Rapid defecation during or after feeding makes T. cruzi transmission efficient.
- Wild populations in palms can reinfest houses after spraying.

## Diseases it causes

- Chagas disease (Trypanosoma cruzi), including oral food-borne transmission [Chagas disease →](https://durgical.com/en/conditions/chagas-disease/)

## Diagnosis

- Species identification by the entomology lab from specimens handed in by the community.
- Search for T. cruzi in the bug's faeces or gut (direct exam or PCR) to measure natural infection.
- House infestation and village dispersion indices to prioritise spraying.

## Treatment

Does not apply to the insect. Control uses indoor residual spraying with pyrethroid insecticides, housing improvement and community entomological surveillance.

Drug class only; doses and regimens are set by the clinician from the current guideline.

## Prevention

- Improving housing: plastering walls, sealing cracks and replacing palm-thatch roofs.
- Indoor and peridomestic residual spraying.
- Keeping chicken coops and stores near the house tidy and using bed nets.
- Taking bugs found at home to the health department for identification.
- Hygiene in preparing juices and food to prevent oral Chagas; screening in blood banks and pregnant women.

## In Colombia

Colombia prioritised eliminating household R. prolixus: in 2013 PAHO certified the interruption of its indoor transmission in 10 municipalities of Casanare, Boyacá, Santander and Arauca, and more followed. Native secondary species, such as T. venosa and P. geniculatus in Boyacá, remain infected and keep the risk alive, along with oral outbreaks.

## Memory aid

The bug slips a letter under the door: it bites, leaves its faeces by the wound, and the person, scratching, opens the door to the parasite.

## Test yourself

Think of the answer, then tap the question to see it.

## How does the triatomine transmit Trypanosoma cruzi?

Through the faeces it leaves next to the bite; the parasite enters when the person scratches or through mucosa, not through saliva.

## What is the main household Chagas vector in Colombia?

Rhodnius prolixus; Triatoma dimidiata, T. venosa, T. maculata and Panstrongylus geniculatus also matter.

## Which triatomine stages can transmit Chagas?

All blood-feeding stages: the five nymphal stages and the adult, male and female.

## Why does improving housing prevent Chagas?

Because plastering walls and replacing palm roofs removes the cracks where the bug hides and breeds.

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## Related

- [Trypanosoma cruzi](https://durgical.com/en/microbiology/trypanosoma-cruzi/)
- [Trypanosoma rangeli](https://durgical.com/en/microbiology/trypanosoma-rangeli/)

## Related conditions

- [Chagas disease](https://durgical.com/en/conditions/chagas-disease/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

[← Back to the group: Arthropod vectors](https://durgical.com/en/microbiology/groups/arthropod-vectors/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Chagas disease (also known as American trypanosomiasis)](https://www.who.int/news-room/fact-sheets/detail/chagas-disease-(american-trypanosomiasis)) (WHO, 2025); [Chagas disease - PAHO/WHO | Pan American Health Organization](https://www.paho.org/en/topics/chagas-disease) (PAHO, 2024); [Triatoma venosa and Panstrongylus geniculatus challenge the certification of interruption of vectorial Trypanosoma cruzi transmission by Rhodnius prolixus in eastern Colombia](https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0012822) (PLoS Neglected Tropical Diseases, 2025).

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Representative model, for educational purposes only.

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