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Bolivia's bug killers: Preventing the spread of Chagas

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Two young men, equipped with a flashlight and an iron rod and carrying some small boxes in their pockets, are looking for insects in each and every one of the 72 houses within the San Simón community. In this village, these youngsters are known as "vinchuqueros" - a play on the words "racheros" (ranchers) and "vinchucas", the name locally given to the bug that carries the Chagas disease. The hunters are working for Médecins Sans Frontières (MSF) as part of its struggle against one of Bolivia's most deadly diseases.

The vinchucas is about 5cms long when fully grown. It climbs high on the clay walls inside the houses and then jumps and glides until it lands on exposed arms of sleeping children. The disease spreads when the bug bites the flesh, defecates and the victim unknowingly scratches minute parasites into the blood system. Then it can linger for years before symptoms start to appear - sometimes 10 or 15 years later

These two 'vinchuqueros' are Félix and Raúl and they sometimes have to walk up to seven hours before reaching a house where they will then search high and low to spot the deadly bug: among the onions, firewood or in untidy farmyards. Children follow them everywhere. "They are our helpers", says Félix.

Félix and Raúl, along with a third member, Jesús, are all of Guarani origin - an ethnic group that makes up one third of the population here - and are in charge of registering the number of children under 15 in each household. That is part of their job as one of the search and kill 'wings' of the Chagas prevention and treatment programme that MSF opened one year ago in Entre Ríos, in O'Connor province, southern Bolivia. In this area, the disease affects 30% of all children under 14. The other "wing" in the MSF programme is treatment.

The search and kill wing is methodical. The team inspects the rooves, walls, rooms, floorboards, checks in the food supplies, in the beds, parcels, wardrobes, cracks and crannies in the mud walls for any sign. It is a thorough inspection for the bugs and their nests. The team checks the area to better target the bugs that may rest there, hidden from view during the inspection. A Government programme does necessary spraying to kill off the bugs.

The eradication is essential for the treatment to be effective. Because, no matter how well an area is cleared of the bug, if it returns, people who have been given treatment can be re-infected. The odds are only barely in the patients favour. The problem is that there is no effective treatment for Chagas. Eradication and treatment are constant companions with Chagas.

"One wing cannot exist without the other", explains Francisco Román, field coordinator in the Entre Ríos municipality, "The treatment is not a vaccine. Children can get infected again that very evening, while sleeping at home. This is why being on the alert for the presence of the vector (the bug) is a must, followed by administering the appropriate treatment".

Recovery is not guaranteed

"Children only have a 60-80% chance to recover. As they get older, though, the side effects of the medicines needed increase while their efficacy decreases", explains Dr Fernando Parreño, the paediatrician in the project.

Bolivia holds the unfortunate record for Chagas infections in Latin America. The disease is endemic in 60% of the country. Half of the population - some 3.5 million people - are at risk. Chagas is said to be the fourth highest cause of disease and responsible for 13% of the total deaths in the country.

In the developed western world, these figures would have long ago motivated pharmaceutical companies to develop a cure - or at least an effective treatment or vaccine. But Chagas is also known as a 'disease of the poor' and this is reason why, for 30 years now, there has only been one treatment, already obsolete: and still the side effects, resistance or incompatibilities are not yet known.

At first, the symptoms are no cause for concern: tiredness and a stomach ache. But later on fatigue extends, takes root in the person, preventing the affected from going to work, raising horses or performing the slightest task. Heart failure is the usual cause of death.

When MSF arrived in Entre Ríos a year ago, the infestation rate for Chagas was 19%. By then the situation as so severe that the most immediate need was to try and eradicate the bug.

"Starting treatment was out of the question", said Román. "However, by fumigating and repairing each and every household as part of the government programme, the chance of infection has decreased considerably."

Filling cracks and repairing roofs reduces the hiding places for the bugs. Entomological search helps determine whether a community is free of "vinchucas" and only when reaching an infestation rate lower than 3% can treatment be started, otherwise it is overwhelmed by re-infection. Currently, MSF is the only organisation offering treatment to children under 14, the age group for whom treatment is most effective.

Community by community, MSF has already visited the six of the most populated communities surrounding Entre Ríos, with the objective of treating 2,000 children in three years and covering the 103 communities within the O'Connor department. The project started in September 2003 and is scheduled to last until September 2005.

Treatment is long

The procedure for treatment is long. First of all, children have blood samples taken and tested; "the use of filter paper for the tests is an achievement as it allows to take samples en masse in rural areas", explains the field coordinator.

Once the laboratory results are ready, the MSF team visits the parents of those children who have tested positive - there have been 606 so far in this community alone - and offers them free treatment. If MSF did not pay for the medicines needed, the affected families, who could get to the pharmacy, would have to pay 50USD per child, a prohibitive amount in such a context.

The only condition to enter the MSF programme is that patients must commit themselves to complete the whole treatment cycle.

"Despite this, the number of defaulters reaches 3% as some leave the place or forget to take the tablets", adds the field coordinator.

In the Buenavista school, several children are already waiting for the Médecins Sans Frontières vehicle. The paediatrician Fernando Parreño shakes their hands with each patient and, after finding their surname on a list, gives each of them a small bag with their nametag attached containing the pills broken into quarter pieces that they will have to take in one week. The method is two quarter pieces per day for a whole week. This means Parreño must break up the pieces per child split as best he can.

"The treatment is complicated but, to top it all off, the main users are children and no formula adapted to children, such as a syrup, has ever been developed", he complained. "MSF administers benzinadol (Roche), a drug which started being used in cattle in the 1970s. Even though Chagas was discovered at the beginning of the century, we know hardly anything about it".

Lack of medical data

There are basic gaps in medical knowledge - information that would seem standard given the extended time the diseases has been known. For instance, the length of a treatment course. As there are no studies on it, MSF has decided to administer it during 60 days, although at the San Juan de Dios Hospital in Tarija, pioneer in the discovery of mother-to-child transmission, only a one-month treatment is given to new born children.

The re-infestation percentage is also unknown, emphasizing the urgent need for long-term studies. However, MSF has stored 600 samples, available for testing by any laboratory who wishes to take on the challenge of this disease and study the prevalence of the disease in children under 14.

"I think nobody has ever stored so many samples", asserts Román at the Entre Ríos hospital. "The idea is to influence on the national protocols and see Chagas addressed as a public health hazard in Bolivia".

The MSF teams take special care of their small patients and keep a watchful eye on any possible adverse reaction. A few days ago, the MSF 4-wheel drive drove for three hours along the road full of bends between Entre Rios and Tarija to refer a Guarani child, Grecia, to the hospital there. Due to an adverse reaction, little Grecia's skin was suffering from a chemical burn - an adverse reaction to the treatment. But even this reaction was a surprise to the MSF staff.

"She is OK now. This is the first time we have seen something like this, but it means we must be very careful", explains Parreño.

Informing the public

MSF has been trying to increase awareness of Chagas in their community through a series of radio commercials. They spots are two to three minutes long and are short radio-theatre style pieces designed to inform people of the diseases and what they can do to prevent it or be treated.

The "actors" speak in their local accent and pretend to be two neighbours meeting each other. One of the neighbours tells the other one that her children should be tested if she wants to prevent "their getting tired and finally die" when they grow older.

Children are most likely to absorb the information. Señor Reinaldo, from the San Simón community, says that his children are very certainly playing their part in the eradication of the vinchuca.

"They grab the bug, separating its head from its body and giving it to the hens to eat". But he also admits not that he did not know how harmful these insects were: "My father died of Chagas, I think. A heart attack".

And like him, so many others have died without knowing why. Now they do know why, but for most of them there is not effective treatment.

MSF Chagas activities

MSF runs a Chagas programe in Bolivia and also runs programmes in Nicaragua, Guatemala and, in the near future, Mexico.

The Bolivia program is titled 'Tarija' , opened in October 2002, and covers the O'Connor province. The team is based in Entre Rios, three hours from the province capital of Tarija, where the Bolivia team is based. MSF staff covers the entire region from this base.

The goal is to diminish prevalence among the 8,300 children under 14 living in the area while organising education, diagnosis and treatment activities.