Development & Aid, Headlines, Health, Latin America & the Caribbean

HEALTH-ARGENTINA: Chagas Disease – Science Progresses as Prevention Efforts Flag

Marcela Valente

BUENOS AIRES, Jul 12 2005 (IPS) - Researchers in Argentina and Brazil are making progress towards coming up with effective treatment for Chagas disease, a parasitic infection that threatens millions in Central and South America.

But in Argentina, the enthusiasm of researchers has been dampened by the fact that the number of people contracting the potentially deadly disease is growing again due to the neglect of basic prevention measures.

Without support from the pharmaceutical industry, which sees no lucrative market in developing drugs against a disease that affects mainly people from low-income strata, medical researchers have demonstrated that Chagas disease can be cured in children under 14 and in adults who have been recently infected.

Advances have also been achieved in treating chronically ill patients in Argentina and Brazil through transplants of the patient’s own stem cells – which divide and replace themselves – into severely damaged hearts.

But Argentina’s late 2001 economic and political meltdown and subsequent crisis led to the collapse of monitoring and prevention systems in the provinces, and the number of new cases is once again on the rise.

Experts also complain that early detection is no longer being practised among babies born to infected mothers, who can pass on the disease to their infants during pregnancy, delivery or breastfeeding.

Chagas disease has three stages: acute infection, in which symptoms occur soon after infection; an asymptomatic phase, which can last months or years; and chronic infection.

In the first stage, which only a small minority of patients suffer, symptoms include swelling of the eye on one side of the face, exhaustion, fever, enlarged liver or spleen, swollen lymph glands, a rash, loss of appetite, diarrhoea, and vomiting.

Symptoms in the chronic stage can appear years or even decades after infection. Health problems include serious, irreversible damage to the heart or intestinal tract.

The disease is transmitted by the reduviid bug (from the Reduviidae family and the Triatominae subfamily), also known as the vinchuca, assassin or kissing bug.

The insect lives in crevices and gaps in poor rural housing – such as thatch, mud or adobe huts – in 18 Latin American countries.

In Argentina, the bugs are found throughout the country, but are especially prevalent in northern, western and central provinces where the climate is warm or temperate but dry.

The infected reduviid bug transmits a protozoan parasite named Trypanosoma cruzi through its faeces, which human victims unwittingly rub into the bite wound left by the bug, or into their eyes, mouth or nose. The parasites thus enter the victim’s bloodstream and gradually invade most organs of the body, often causing severe damage to the heart, digestive tract or nervous system.

An estimated 32 percent of those infected die from organ damages during the chronic phase. Two of every 10 cases of severe damages to the heart caused by Chagas disease occur in people between the ages of 20 and 40.

Brazilian physician and infectologist Carlos Chagas (1879-1934) discovered the parasite before the disease itself was even identified. His work was unique in that he completely described a new infectious disease, including the pathogen, vector, host, clinical manifestations, and epidemiology.

In an interview with IPS, Dr. Andrés Ruiz, director of the “Dr. Mario Fatala Chabén” National Institute of Parasitology, said that despite the recent progress towards effective treatment and a cure for the illness, Argentina’s severe 2001-2002 economic crisis led to a major setback in the fight against the disease.

“Unfortunately inspections of housing have come to a halt in many provinces, and today we are seeing an increase in the number of people infected,” said Ruiz.

Some 2.3 million people in this country of 37 million were found to be infected with Chagas disease in 1993, when the last estimate was made based on testing of young people who were entering military service, which was compulsory at the time.

Throughout Latin America, an estimated 16 to 18 million people are infected, with around 50,000 dying of the disease each year.

Although most patients contract the disease after they are bitten by the reduviid bug, which comes out at night from cracks in the walls and roof to feast on its victims, infected women can also pass the parasite to their babies, and infection can be transmitted by blood transfusions or organ transplants.

As of yet there is no cure or vaccine, and in most cases only treatment of symptoms is possible. But while current medications can reduce the duration and severity of an acute infection, they are at best 50 percent effective in eliminating the parasites.

Argentina’s efforts to eradicate Chagas disease include a nationwide programme for spraying in homes to eliminate reduviid bugs.

But the programme, which involves inspections and close monitoring by health authorities in each province in order to prevent further infestations, was left without financing by the crisis, and the insects once again began to reproduce in poor housing in rural areas.

According to the Health Ministry, the number of new infections of Chagas disease in Argentina had plunged to just six in 2001. But since then the number has grown steadily, to 11 in 2002, 18 in 2003, 21 in 2004 and 24 so far this year.

Although infections transmitted by the bugs were never completely eliminated, the situation had improved markedly from the nearly 300 new cases registered annually in a single province in the 1960s, Ruiz noted.

With respect to infants infected by their mothers at birth, the increase in the number of new cases could be even greater, although there are no statistics because babies are no longer monitored.

The institute headed by Ruiz estimates that seven percent of the 600,000 annual births in Argentina are to women with Chagas disease. An average of four percent of these mothers pass the disease on to their babies.

These statistics indicate that some 1,700 children are born with Chagas disease every year. To diagnose the disease, infants born to infected mothers must be monitored for one year. If the disease appears during that time, they can be cured through 60 days of treatment with the currently available drugs.

However, only 400 children a year now receive this treatment. “That means we have 1,300 children who are not being treated although they are probably infected, and who could develop the disease when they reach adulthood,” said Ruiz.

He also pointed out that Chagas disease is one of the public health problems that are largely ignored by the pharmaceutical industry, which is not especially interested in developing drugs or vaccines for diseases that mainly attack the poor.

“If we detect the real number of children who should be receiving treatment and we show how effective the treatment can be in acute or chronic patients, the market would be more attractive for the industry, even if the client is the state,” he argued.

Laboratories in Argentina and Brazil have developed drugs that have been successfully tested in mice, but the researchers are now in need of financing to move on to clinical trials in human patients.

The “Dr. Mario Fatala Chabén” National Institute of Parasitology is developing new drugs for treating patients, while investigating the genome of the parasite and studying the effectiveness of treatment in patients who have suffered severe damage to their hearts.

“Up to six years ago, people said it was useless to treat either the recently infected or the chronically ill. But today we know that the disease can be cured in children under 14 and in recently infected adults, and that progress has been made in the treatment of chronic patients,” said Ruiz.

In Argentina and Brazil, medical researchers have made advances in treating chronic patients by transplanting stem cells from the patients’ own bone marrow into their severely damaged hearts.

Promising initial results were obtained in two patients in Argentina and 20 patients in Brazil, through a procedure that does not even require surgery, since the stem cells are delivered to the walls of the heart through a catheter.

“We are now going to test this on 50 patients,” Ruiz enthused. “Of course, after that we have to make sure the patient is not bitten again by the vinchuca bug,” he underlined.