Verity Bowman

Sometime in the next decade, a woman in Buenos Aires will go to her cardiologist complaining of breathlessness and fatigue. 

She will be told she is in heart failure. 

The damage, her doctor will explain, is irreversible. 

What nobody will tell her – because nobody will know – is that she has been infected since childhood, carrying a parasite that spent thirty years quietly destroying her heart muscle while she felt completely well.

She is one of an estimated six million people across Latin America living with Chagas disease, which experts describe as a “ticking time bomb” in the region’s cities.

“People often acquire the infection as children while living in rural areas, and then they carry the infection for life unless they receive treatment,” David Moore, a Professor of Infectious Disease and Tropical Medicine at LSHTM, told The Telegraph. 

“As a result, some of them have what is essentially a ticking time bomb, developing cardiac disease many years later.”

Chagas disease is caused by the parasite Trypanosoma cruzi, which is carried by the triatomine bug, a blood-sucking insect that lives in the cracks and mud walls of rural housing across Latin America.

For centuries, that kept Chagas rooted in rural areas, but mass migration across Latin America changed that.

The movement of people into cities has opened up new routes of transmission, including contaminated food and drink, blood transfusions, and mothers unknowingly passing the parasite to their children in the womb.

Of those infected with Chagas, around 30 per cent will go on to develop serious cardiac complications, including stroke, arrhythmia, heart failure, typically decades after infection, as the heart muscle slowly enlarges and weakens.

Both available treatments, benznidazole and nifurtimox, are nearly 100 per cent effective if given early, but this rarely happens, as around 70 per cent of those infected have no idea they carry the parasite.

“After infection, there can be a very long silent period. People can feel completely fine, actually perfectly healthy, so they don’t really see the value in seeking testing,” said Professor Hany Elsheikha of the University of Nottingham. “Many doctors are not very aware of it either, so they don’t suspect it.”

Infections of Chagas are most common in Brazil, Argentina, Bolivia, and Venezuela, with Bolivia having the highest national prevalence as high as 80 to 115 new cases per 100,000 people per year. 

Professor Elsheikha explained that the disease’s movement from rural areas was a “silent introduction”, driven largely by migration. 

As a result, in Brazil, the consumption of acai juice has become a focal point of transmission.

Triatomine bugs, or their faeces, contaminate the fruit during harvesting or processing, and the parasite survives in the juice unless it is pasteurised.

“You’re not being bitten,” explained Professor Moore. “You’re ingesting something that may be contaminated: a crushed insect, or fruit contaminated with insect faeces that hasn’t been properly washed or processed.” 

Oral transmission is now the most common type of transmission in Brazil, accounting for more than half of all recorded acute cases in the country, according to the United States’ National Institutes of Health (NIH).

Diagnosis usually happens almost accidentally, usually in blood donation screening, pregnancy tests, or organ transplant checks.

In many countries, fewer than one in ten infected people are ever diagnosed, and in some, fewer than one in a hundred, the World Health Organization has found.

“In Latin America at the moment, maybe only 10 to 20 per cent of people are actually diagnosed, which basically means that around 80 to 90 per cent may not even know whether they are infected or not,” said Professor Elsheikha. 

But the most significant transmission route of all requires no bug, no contaminated food, and no medical procedure – just a mother who does not know she is infected.

When a pregnant woman carries the parasite, it can cross the placenta and infect the unborn child. 

Around five to ten per cent of pregnancies where the mother is infected result in congenital transmission.

As most infected women have no symptoms and no diagnosis, the vast majority of those pregnancies go undetected and unmonitored.

Programmes to interrupt this are now running in several Latin American countries, but coverage is far from universal.

“Among such a large number of women of childbearing age, congenital transmission has become the principal mode of transmission,” said Professor Moore. “More new infections now occur this way than through any other route.”

He added that in order to interrupt this, a system in which pregnant women at risk are tested is vital, but that this is still very poorly implemented across the region.

“There are multiple factors involved… You’re also talking about poor resources, limited healthcare capacity, lack of awareness, and socioeconomic barriers,” added Professor Elsheikha.

“Many of the people affected are migrants or come from lower-income backgrounds, so they often have limited access to healthcare, which creates additional constraints.”

Treatment, when it does happen, is far from straightforward. 

The available drugs must be taken for weeks or months and carry significant side effects, including fatigue, rashes, and nerve damage, which lead many patients to abandon the course before it is complete. 

Even when someone is diagnosed, Professor Elsheikha said, treatment completion rates are very low.

So, for the millions living with Chagas disease who will never be treated and tested, irreversible damage will arrive without warning – just as it will for the woman in Buenos Aires.

Professor Moore said: “By that stage, it’s often quite late, because the damage is already done.”

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