Chagas disease

The disease caused by this protozoan, related to others such as those that cause sleeping sickness in Africa (African trypanosomiasis) or leishmaniasis, is called American trypanosomiasis or Chagas disease in honor of the Brazilian physician Carlos Ribeiro Justiniano Chagas, who described it in 1909.

It is a disease that is endemic in much of South America but it has also spread to Central and North America, as well as to the European continent due to the migratory flows of people from these areas.

Causes

Chagas disease is caused by a protozoan, Trypanosoma cruzi, which is transmitted to man by the bite of various types of blood-feeding insects. The main transmitter vector of Trypanosoma cruzi is a species of bedbug that lives in South America and is called vichunca.

The natural reservoir of this protozoan are marsupials, rodents, primates and bats. When the insects are bitten, they absorb the protozoan with the blood and can inoculate it to man by stinging him in turn.

The Trypanosoma cruzi cycle is divided into two phases, the one that takes place within the insect and the one that occurs within man, which is when Chagas disease manifests itself.

When the insect acquires blood contaminated with Trypanosoma cruzi by biting an infected animal or person, the protozoan multiplies within the insect's stomach and passes into the intestines, where it matures and becomes infective. To the biting the insect to the man contaminates with his feces filled with these protozoa the wound from the bite that causes it and the Trypanosoma cruzi enter the body of the human being.

They enter the cells in the area of ​​the bite and multiply there until the cells that contain them break, thus accessing other cells and also the bloodstream, so that they spread to other parts of the body, especially muscle cells, heart, liver, spleen, and intestines. By circulating through the blood, if an insect bites this infected person, it can absorb these protozoa and the cycle begins again.

Other less frequent forms of transmission are contact with food containing the parasite, bites or wounds caused by animals contaminated with Trypanosoma cruzi, infected blood transfusions or what is known as vertical transmission, from the infected mother to the fetus.

Symptoms

Chagas disease has an evolution in different phases, an acute and a chronic one.

In the acute phase, after the bite, a lesion occurs in the area of ​​the inoculation, a skin bulge called chagoma. Often the sting occurs in the conjunctiva, which is why it usually appears, edema around the eyes and inflammation of the lymph nodes in that region, symptoms that are known as the Romagna sign. This phase usually lasts about two months.

From there there may be secondary symptoms to the proliferation of parasites in the different tissues of the body, being common to present:

• Fever
• Tiredness and lack of appetite
• Enlargement of the liver (hepatomegaly) and spleen (splenomegaly)
• Lymph node swelling
•  

In severe cases of the disease, meningoencephalitis can occur, which usually has a poor prognosis.

In 30-40% of cases that have not received treatment during the acute phase, the disease becomes chronic. Years and decades may go by without new symptoms appearing, but then it is seen that these patients suffer one due to the involvement of the cardiac walls by Trypanosoma cruzi, which in the long run leads to heart failure, which when established usually causes heart failure. death in a few years.

Likewise, approximately 10% of these patients suffer from alterations of the digestive system, in general dilations of the esophagus or colon, which alters the absorption of food, produces reflux, abdominal pain and an increased risk of intestinal perforation.

Some of these patients also suffer from central nervous system involvement, which can lead to a state of progressive and irreversible dementia.

Diagnosis

The diagnosis of Chagas disease should be suspected in people who have been in areas where the disease is endemic and who have been bitten by an insect. The patient should be questioned about the history of these bites, the existence of the initial chagoma, and the symptoms of the acute phase described above.

The best method of detecting the acute form is by looking for parasites in a fresh blood sample.

It is advisable to perform a, a chest x-ray and a to assess possible cardiac involvement, as well as an abdominal ultrasound to assess the liver and spleen.

In the chronic form, IgG antibodies against the parasite can be detected in the blood, which is not possible in the acute form of the disease.

Treatment

Treatment of the acute form is based on the use of two drugs, nifurtimox and benzinidazole. With these treatments, a cure is achieved in approximately 70% of cases and the disease is prevented from becoming chronic in more than 90% of patients.

These two drugs, however, are effective in less than half of patients in their chronic form. Obviously, it will be necessary to apply the necessary medical and surgical treatments to treat heart failure and the possible digestive and neurological alterations of the chronic form of Chagas disease.

Trials are underway with a new drug that appears to be capable of killing Trypanosoma cruzi. It is posaconazole, which is an antifungal drug for hospital use, but whose use for the treatment of Chagas disease is still under study.

Precautionary measures

Chagas disease lacks a preventive vaccine. The best way to protect yourself from its contagion is to avoid the bites of the insects that can transmit it if you have to visit regions where it is endemic. When traveling to these areas it is advisable to always wear long sleeves and long pants, cover your feet and head, wear sunglasses and spray yourself with insect repellants.

It is also important to be careful with wild animals, food, water and possible contact with contaminated blood (tattoos or wounds). In case of suspicion of having been infected with the disease, it is important to approach a hospital center as soon as possible.

Relevant data

The World Health Organization (WHO) ranks Chagas disease as one of the 13 most neglected diseases in the world and is a poverty-related disease. It is estimated that around the world there are about 10 million people infected with Trypanosoma cruzi, while about 25 million people are at risk of contracting it. In 2008 it was the cause of the death of about 10,000 people according to WHO estimates.