Chagas disease

Content

Introduction

Introduction

Chagas disease (also known as American trypanosomiasis) is an infectious disease caused by the protozoan Trypanosoma cruzi. The disease is widespread in Central and South America and is not present in Italy and Europe, the ascertained cases were people from Central and South America, or tourists who had visited those areas.

It is mainly transmitted by the bite of bed bug-like insects and is the third most frequent parasitic disease in the world. After the infection, the infected person may not have any trouble for years, even for decades, but the parasite in the body can cause damage to the nervous system, heart and intestines. Due to the absence of ailments (symptoms), many people do not know they are sick and do not cure themselves for a long time, facing very serious consequences that can even lead to death.

Insects that transmit the protozoan Trypanosoma cruzi are theTriatominae, very similar to bedbugs and widespread only in Central and South America. THE Triatominae they are between 1 and 4 centimeters long and feed on blood. They are active only at night and during sleep they can prick the skin on uncovered parts (especially the face) to feed themselves. During the blood meal they release feces containing the parasite and humans become infected by scratching or putting hands contaminated with the parasite's feces in their mouth or eyes.

Other rarer causes of contagion can be transfusions or transplants from infected people (risk that in Italy is excluded due to strict controls in the selection of the donor), transmission from mother to child during pregnancy or childbirth and the ingestion of contaminated food .

Symptoms

Symptoms

The incubation of the disease is about one or two weeks from the bite of the bug, it can be longer if it is an infection following a transfusion or transplant. After the incubation period, on the area where the insect bite took place (usually the face, near the eyes or lips) a swollen, red lump may appear and fever may occur.

Subsequently, the local disturbances (symptoms) and the fever disappear and the disease may not cause any disturbance for years. In this phase, the disease can only be identified by carrying out a specific search for antibodies against the parasite or for protozoa in the blood.

After years, about 20-30% of people who have contracted the infection can develop the chronic form, following the severe damage caused by the parasite to the nervous system, heart, intestine or esophagus.

Causes

Causes

The main cause of transmission to humans of the disease is the bite of the bedbug Triatominae. This insect is widespread only in Central and South America and lives mainly in the cracks and crevices of the walls, in the thatched roofs of "adobe" houses (brick made from a mixture of clay, straw and sand), in farm buildings, in piles of stones or wood, in chicken coops and dog kennels. The bedbug is active only at night and during sleep it can sting the skin on uncovered parts (especially the face) to feed itself. During the blood meal it releases feces containing the protozoan Trypanosoma cruzi on the skin. The insect bite causes intense itching and humans become infected by scratching or bringing hands contaminated with the parasite's feces to the mouth or eyes.

Other rarer causes of contagion can be transfusions or transplants from infected people (risk which in Italy is excluded due to strict controls in the selection of the donor), transmission from mother to child during pregnancy or childbirth and the ingestion of contaminated food.

Diagnosis

Diagnosis

The ascertainment of the disease (diagnosis) usually occurs through the search in the blood for antibodies produced by the body's defense system against the protozoan. It is also possible to determine the presence of the protozoan by directly observing a blood sample under a microscope.

In a more advanced stage, it is possible to detect the presence of the protozoan also by examining a sample from an infected organ.

If the disease is ascertained, investigations are performed on the conditions of the heart, esophagus and intestine (electrocardiogram and CT scan).

Therapy

Therapy

The therapy is basically pharmacological and is especially effective if started during the first weeks after infection. In this phase the drugs rapidly lower the number of protozoa present in the blood and shorten the duration of the disturbances (symptoms). When the infection becomes chronic, instead, drugs decrease the risk of death.

There are two drugs used to kill the parasite:

  • benznidazole
  • nifurtimox

However, their effectiveness is limited. To these can be added a generic therapy for the treatment of ailments.

For the moment there is no vaccine against the disease, the most effective method is to protect yourself from the bites of triatomine bugs by using insect repellents and periodically disinfecting the rooms, and to observe basic hygiene rules (wash your hands often with soap and water).

Bibliography

Bibliography

AILMAC Onlus. Italian Association for the Fight against Chagas Disease

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