Media playback is unsupported on your device Media caption A disease once confined to Latin America now has become global

A silent killer once confined to Latin America now has gone global. The "assassin bug" - which spreads Chagas disease - thrives in countries like Bolivia. But up to 80,000 migrants from Latin America are now living with the illness in Spain - and no one can predict who will get serious health complications.

Every time Briggitte Jordan remembers the first time she heard of Chagas she becomes tearful. When she was a teenager living in Bolivia, Briggitte's mother told her that she'd tested positive for Chagas.

"The doctors didn't give her much information, only that she was another statistic, and what was going to happen was that my mother might die young," she recalls now living in Madrid, nearly 20 years later.

Chagas is spread by the bite of an insect - the "assassin bug" - which infects people with a parasite. If untreated, this can cause organ damage and lead to premature death.

But in the early stages there are few or no symptoms, so getting the word out about the disease is essential.

Football is like a magnet for most Latin Americans, so today Briggitte is at a match at Villaverde sports centre in Madrid. She and her colleagues from Mundo Sano (Healthy World) give out balloons and ribbons to spectators.

Image copyright Mundo Sano Image caption Briggitte and her colleagues take every opportunity to talk about Chagas with their fellow Latin American expatriates.

As the whistle blows for half time, traditional Bolivian dance is performed on the pitch, while the talk on the touchline is all about Chagas. They hope myth-busting and accurate information will encourage people to get tested.

And so they should: the parasite Trypanosoma cruzi that causes the disease hides inside the muscle fibres of the heart, the digestive system or peripheral nervous system, gradually damaging organs.

By the time they notice symptoms, patients may have developed serious complications in the heart or digestive system.

Briggitte thought her mother would only live until her 40s or 50s. "That's what you hear in our country."

Dreaded result

Why is it called Chagas? Image copyright WIKI COMMONS Carlos Chagas was the Brazilian doctor who first described Chagas disease, also called American trypanosomiasis, in 1909. The son of coffee farmers, it was his uncle who persuaded him to study medicine. After graduating in 1902, he started working with the epidemiologist Oswaldo Cruz in Rio de Janeiro. In 1909 he was sent to a small town called Lassance to fight a malaria outbreak. It was there where he spotted a peculiar infestation of an insect in rural houses. He also observed that it bit people around their mouth and eyes - hence its nickname "the kissing bug". Chagas later discovered that the insect had a parasite that could be passed to other animals, such as monkeys, through its bites. He suspected it could also be causing disease in humans. On April 23rd that year he discovered the presence of the parasite Trypanosoma in the blood of a three-year-old girl. She became his first human case.

The nocturnal insect that spreads Chagas is widespread in the Americas. Officially called Triatoma infestans, its habit of biting humans around the mouth gave it another nickname - 'the kissing bug'.

Like another 2.3m Latin Americans who have moved abroad, Briggitte and her mother migrated to Spain, where they found out that treatment was available.

They also discovered there was a chance Briggitte could have Chagas, since a mother can pass it onto her child before birth.

In parts of the world where the kissing bug doesn't exist, the parasite can still be spread by infected people via blood transfusions, organ transplants, or in the womb.

Outside Latin America, the United States has the highest number of cases, followed by Spain. It is estimated that between 40,000 and 80,000 Latin Americans in Spain - mainly from Bolivia - have either the disease or the parasite. And around 90% of those do not know they have it.

It took Briggitte more than a year to overcome her fears and finally get tested.

"To be honest, I was afraid. I missed one or two appointments and I think it was at the third one that I finally decided to get screened."

After two weeks she got the news that she dreaded: she had tested positive.

Preventing transmission

Even though 70% of people with the Chagas parasite will never develop symptoms, they can still pass it on.

That's why preventing transmission from mother to child is a key challenge, according to Dr Miriam Navarro, a researcher from Mundo Sano, an organisation in Spain that helps to control and eliminate neglected diseases.

"It is compulsory to check blood transfusions and organ transplants, but we don't have a protocol to screen all pregnant women who are from Latin America.

Image caption Health workers from Mundo Sano give more in-depth talks to Latin Americans, mainly mothers and young women.

"Even though at the moment many doctors are aware of Chagas disease, there is still a lack of information."

Altagracia Prieto is another Bolivian woman who tested positive. She saw three specialists before the test was offered to her.

"I've always suspected that I had Chagas. We had the insect at home [in Bolivia], but because I never developed symptoms I wanted to believe I didn't have it."

Dr Navarro runs the awareness campaign Madres comprometidas con la enfermedad de Chagas (Mothers against Chagas disease), to get as many people diagnosed as possible.

"The main difficulty that we face is the lack of information from migrants coming from endemic areas."

"We have to let people know that a treatment is available for Chagas disease, a treatment that in many patients works well," adds Navarro.

There are just two drugs available to treat the parasite that causes the illness, benznidazole and nifurtimox.

Both medicines were developed in the 1970s. They have to be taken for two months and each can have strong side effects - such as allergic dermatitis with benznidazole and polyneuropathy - a disease affecting peripheral nerves - with nifurtimox.

"Relief"

Symptoms Image copyright SPL Acute phase : It usually passes unnoticed or it has mild ones that are not unique to Chagas, such as fever, fatigue, body aches, headache, rash, loss of appetite, diarrhoea and vomiting. The most recognised marker of this phase is the swelling of eyelids on the side of the face near the bite wound.

: It usually passes unnoticed or it has mild ones that are not unique to Chagas, such as fever, fatigue, body aches, headache, rash, loss of appetite, diarrhoea and vomiting. The most recognised marker of this phase is the swelling of eyelids on the side of the face near the bite wound. Chronic phase: After remaining silent for decades, some people develop cardiac and intestinal complications, which can include enlargement of the heart, heart failure, altered heart rhythm and cardiac arrest, or enlarged oesophagus or colon.

"However, this is what we currently have and they are effective," says Navarro, who also explains that the latest research shows that treatment before pregnancy prevents transmission to the child.

That is what motivated Briggitte to make up her mind to be treated. She was 25 and wanted to have a family, but didn't want to pass the parasite on to her future offspring.

Her body rejected benznidazole and she had to go for the second drug option. Five years after the treatment, the levels of antibodies show a significant reduction in the level of parasite infection in her body.

Currently there is no specific test for Chagas, so the only way to detect its presence is by checking the levels of specific antibodies. After the treatment, the patient has to be tested regularly for those levels.

Together with Altagracia and two other Bolivian mothers who have Chagas, Briggitte now takes every opportunity to talk to people in Spain - especially mothers or young women - about this silent killer.

They go to churches, football matches and pubs. They have a free help-line for people to call and even accompany them to hospital to get screened - because they know how difficult that first step can be for those fearing the worst.

As for her own condition, Briggitte has learned to be positive about it.

"I'm very calm, because watching my daughter and knowing that she doesn't have it is a relief."