What is Chagas-Mazza disease
Chagas disease has been included by the WHO among the 17 diseases designated as “neglected diseases”. They bear this denomination in view of the low concern by the governments and the health systems. This disease afflicts the poorest populations, living in rural areas and urban centers of developing countries as well as in developed countries. These diseases generate many disabilities and a high mortality rate.
Chagas disease is the main parasitic disease in the Americas, produced by a single-celled parasite called Trypanosoma cruzi. It is strongly associated with poverty and poor socioeconomic conditions.
The endemic area (where there is a vector) extends from the South of the USA, to the parallel 42 in South America, approximately. According to the WHO, there are currently 8 million patients worldwide, 30% of which develop heart or digestive disease with high mortality rate.
Up to 30 years ago, patients were mainly detected in rural areas, housed in mud houses where the vector lives. In recent years, there has been an important migratory flow worldwide; people abandon their rural homes and migrate to urban centers. This has determined a new epidemiological situation: the disease has been urbanized, generating new cases in cities of America and other continents. As a consequence, people with Chagas disease live in many countries outside the endemic area; for example, in the USA over 300,000 people are estimated to be affected, and in Spain, approximately 80,000.
Although actions to fight the vector have been taken in the last decades, in Argentina, estimates indicate that there are 1,500,000 infected people, 1,300 children are born with this disease and 10 people die each week.
An action plan against this disease should consider:
- Reduce the rate of new cases by:
- Spraying the rural houses in endemic areas with insecticides.
- Adequate control at Blood Banks.
- Treating infected girls, adolescent girls and women of child-bearing age; those who receive parasiticide treatment do not give birth to children with this pathology.
- Care for the infected patients.
The parasite spreads to humans through the following routes:
- Vectorial, through the dejection produced during the sting of the vector.
- Vertical, a mother with Chagas disease can transmit the parasite.
- Blood Transfusion, when the blood of a donor with Chagas disease is not discarded.
- Oral, due to ingestion of contaminated food by the protozoan.
- Organ Transplantation or laboratory accident. Less frequent.
There are basically two criteria to describe the phases of this disease; in Argentina they are the following:
- Acute phase, which are the two first months of the infection, independent of the route of transmission. Diagnosis must be carried out only through direct parasitological methods.
- Chronic phase without demonstrable pathology, these are patients presenting two reactive serological techniques with normal complementary examinations (ECG, chest Rx, Echocardiogram).
- Chronic phase with demonstrable pathology, cthese are patients presenting cardiac and/or digestive clinical manifestations, ECG, Echocardiogram, digestive tract Rx alterations.
- Reactivation, presented by patients with chronic Chagas disease who through immunosuppression (HIV, oncological treatment, organ transplantation) reactivate the disease. Usually, these are serious clinical conditions.
There are now efficient tools to make the diagnosis.
- Parasitological techniques, useful for the acute phase: Microhematocrit, Microtube, Fresh Drop, Xenodiagnosis.
- Serological techniques, used for the chronic phase, to evaluate parasitological cure, for the study of blood donors, for population studies. The most frequent techniques with ELISA, IFI, HAI, WB.
- PCR, - which enables the detection of parasite DNA in different fluids and tissues, is used at present only for research works.
Today, it is estimated that only 1% of the patients received parasiticide treatment, partly due to the difficulty in accesing to medicines.
So far, there are two medicines for the treatment of Chagas disease: Benznidazole and Nifurtimox, both developed in the ‘70s. Drugs for other diseases have been tested, but they have not proven effective for this disease. The disadvantage with Benznidazole resides in its higher rate of adverse events, which turn out to be more significant the greater the age of the patient.
The best response - either with nifurtimox or with benznidazole - is obtained when used in patients in an acute phase, and they have lower efficacy in the chronic phase.
Patients with Chagas disease are part of the population with fewer resources; many of them ignore they have this disease, nor do they know that they are entitled to be treated.
This disease requires a strong commitment of those responsible for health, to establish actions geared towards the prevention as well as the treatment of already infected patients.