Science for Brazil (Reino Unido)

Tropical “Kiss of Death” goes global

Publicado em 21 março 2013

The cockroach-like Kissing Bug (Triatoma infestans) has the ability to feed on human blood and may attack the face or lips while its human victims are asleep, infecting them with a trypanosome parasite  (Tripanossoma cruzi ) that causes heart enlargement, cardiac disease, intestinal damage, lethargy and even death.

In fact, they’re already calling it “the new AIDS” – a disease that’s associated with poverty, degraded habitations, poor sanitation and all the attributes of what was once called the ‘Third World.’ Only Chagas Disease isn’t making a name for itself in Burundi, Bhutan or Burkina Faso.

It’s a neglected tropical disease that’s now spreading rapidly within the warmer parts of the United States and wherever pockets of poverty, inequality and economic migrant misery are found in other developed nations. The Center for Disease Control says some 20,000 people a year die of this disease worldwide, and scientists quoted by Forbes magazine believe there may be up to one million potential sufferers in the US alone.

In fact, experts say that although it’s still almost unknown, Chagas Disease now poses a greater economic burden to the American healthcare system than Cholera, cervical cancer or Lyme Disease. A 2012 report in the New York Times  put the annual Chagas-related bill globally at US$ 7 billion and US$900 million in the United States.

Another report in the same newspaper, authored by Peter Hotez, dean of the National School of Tropical Medicine at Baylor College, firmly linked the rise of this neglected tropical disease in the United States to a decline in sanitary vigilance,  budget cuts in epidemiological services  and the rise of social inequality. It is particularly prevalent in US Gulf Coast states of Louisiana, Mississippi and Alabama,  where poverty rates are near 20 percent.  An estimated 2.8 million children are living in households with incomes of less than $2 per person per day, and are under greatest threat.

Tropical Diseases: The New Plague of Poverty

The US is not alone.  Research by Tsutomu Takeuchi, director of the Institute of Tropical  Medicine at the  University of Nagasaki in Japan, showed that Chagas Diseases is fast becoming a global menace. In recent decades, a combination of economic stagnation and  political repression in Latin America, combined with  the forces of globalisation, have led to unprecedented flows of economic migrants who have helped spread the disease.

Dr Takeuchi’s research was presented at a joint conference of Japanese and Brazilian researchers held in Tokyo in March and sponsored by the Japan Society for the Promotion of Science. The Japan-Brazil symposium on research collaboration  held 15-16 March, was jointly sponsored by  the São Paulo Research Foundation. Sharing scientific data between Japan and Brazil is important because during the last century there was a traditional flow of  migrants  into Latin America, which has been partly reversed in recent decades.

Dr Takeuchi showed that in 2006, almost 4% of immigrants to Australia were carriers of the Tripanossoma cruzi parasite. Likewise in Spain an estimated 5.2% of all the 1.68 million immigrants from Latin America were carriers, with some  17,000 developing the disease in 2008. In the city of Barcelona alone, Dr Takeuchi’s research showed, there were 22 cases during that year, 21 of them originating from Bolivia.

Bolivia is also a source for the spread of Chagas Disease into the US, Dr Takeuchi’s research found. Among the more than 20 million Latin Americans living in the US,   an estimated 6.75% of Bolivian migrants and  4.13% of Argentinian migrants, were carriers of the disease.

Just how could this disease have burst out of control, where does it come from, and  what do we know about it?

Chagas, named after the Brazilian doctor who discovered it in 1909, is also known as American trypanosomiasis. It was believed to be endemic only in the Americas.

As a first stage, Chagas or the parasite Trypanosoma cruzi, is transmitted to animals and people by insect vectors that are found only in the Americas. These blood-sucking triatomine bugs get infected by biting an infected animal or person. Once infected, the bugs pass T. cruzi parasites in their faeces. However, secondary infections are caused by blood transfusion, organ transplantation, and mother-to-baby (congenital transmission). These secondary infections, of course, could happen anywhere on the planet.

One of the few countries where Chagas infections and disease control is going in the right direction, is Brazil. About 2 to 3 million people are estimated to have been infected in Brazil, 600,000 of them with chronic heart or digestive complications, causing death in about 5,000 individuals each year. However, these are mostly old infections, In 2008, the Brazilian government  was recognised by the World Health Organisation as having sucessfully eliminated primary infections from the Kissing Bug.

Data published in the Public Library of Science (PLOS)  cites the epidemiology of mortality rates  linked to Chagas disease in Brazil, as declining significantly in the period  1999 – 2007. However, said the PLOS report’s authors, “Despite the decline of mortality associated with Chagas’ disease in Brazil, the disease remains a serious public health problem with marked regional differences.”

In fact, Brazil may have much to teach developed nations now battling this new disease.  For almost a century, rural extension public health teams travelled the Brazilian backlands in pursuit of the “barbeiro” or Kissing Bug, using insecticide to eradicate the insect from its habitat in the walls of daub-and-wattle mud buildings. Even in remote places and at times when the state held almost no sway, the  “Man from SUCAM”, the rural disease-fighting agency,  was a familiar and respected figure.

Lately, Brazil has been busy sharing its knowledge through conferences and academic exchanges such as the Brazil-Japan symposium. The country’s experience may yet provide vital clues to stopping this gruesome  and neglected tropical disease, from going  global.