The Triatomine or Kissing Bug

Mar 01, 2009 Features / Columnists, Interesting Creatures in Guyana

A kissing bug prepares to feed

The Triatomine is a bloodsucking arthropod vector which has the ability to transmit the Chagas parasite, Trypanosoma Cruzi (T Cruzi), to humans and wild mammals.
Chagas is a disease which the local Health Ministry is currently paying keen attention to and will soon make it mandatory that blood being utilised for medical purposes is thoroughly screened for it.

The members of Triatominae are also known as conenose bugs, kissing bugs, assassin bugs or triatomines.
Most of the 130 or more species of this subfamily are haematophagous – that is, they feed on vertebrate blood. Very few species feed on other invertebrates but they are mainly found and are widespread in the Americas, with a few species present in Asia, Africa and Australia.

According to reports from the local Ministry of Health, the presence of the bug in Guyana was first detected some five years ago when a patient was diagnosed with the Chagas disease following a laboratory test.
These bugs usually share shelter with nesting vertebrates, from which they suck blood. In areas where Chagas disease occurs, all triatomine species are potential vectors of the Chagas disease, parasite T. Cruzi.
It is said that domestic and sylvatic species are the ones that are able to carry the Chagas parasite to humans and wild mammals, however birds are immune to the parasite.

T. Cruzi transmission is carried mainly from human to human by the domestic kissing bugs; from the vertebrate to the bug by blood, and from the bug to the vertebrate by the insect’s faeces and not by its saliva as occurs in most bloodsucking arthropod vectors such as Malaria mosquitoes.
It was revealed during a workshop held by the Health Ministry last week that the triatomine bug is able to transmit the T. Cruzi parasite to humans if its faeces comes into contact with broken skin or if it enters an individual’s mouth.

The disease may also be spread through blood transfusion and organ transplantation, ingestion of food contaminated with parasites, and from a mother to her foetus.
The symptoms of the Chagas disease vary over the course of an infection. In the early, acute stage, symptoms are mild and usually produce no more than local swelling at the site of infection.
As the disease progresses, over the course of many years, serious chronic symptoms can appear, such as heart disease and malformation of the intestines. If untreated, the chronic disease is often fatal. Current drug treatments are generally unsatisfactory and available medications are said to be highly toxic and often ineffective, particularly those used to treat the chronic stage of the disease.

It was in the year 1909 that Brazilian doctor, Carlos Chagas, discovered that these insects were responsible for the transmission of T. Cruzi to many of his patients in Lassance, a village located on the banks of the São Francisco River in Minas Gerais, Brazil.

Poor people living there complained of some insects they called barbeiros that bite during the night.
Another Brazilian, Herman Lent, a former student of Carlos Chagas, became devoted to the research of the triatomines and together with Peter Wygodzinsky made a revision of the Triatominae, a summary of 40 years of studies on the triatomines up to 1989.

Triatomines undergo incomplete metamorphosis and are a wingless first instar nymph that hatches from an egg and is about the size of the tip of a fork. It usually passes through second, third, fourth and fifth instars at which point it turns into an adult, acquiring two pairs of wings.
It is said that adults produce a pungent odour when disturbed, and are also capable of producing a particular sound by rubbing the rostrum over a stridulatory sulcus under the head.
All triatomine nymph instars and adults are haematophagous and require the stability of a sheltered environment where they aggregate.

Most triatomines aggregate in refuges during the day and search for blood during the night when the host is asleep and the air is cooler. Odours as well as heat guide these insects to the host. Carbon dioxide emanating from breath, as well as ammonia, short chain amines and carboxylic acids from skin, hair and exocrine glands from vertebrate animals, are among the volatiles that attract triatomines. During the night, adults of diverse species fly to houses attracted by light.