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What is Chagas disease?

Chagas disease is caused by infection with a parasite called Trypanosoma cruzi. It affects
around 7 million people worldwide. The parasite is found throughout Mexico, Central and South America and the disease affects people from these countries, particularly those who live or have lived in rural areas.

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The insect that spreads the disease is not found outside Latin America. However, once a person has the infection, they remain infected for decades, often with no signs or symptoms of illness. As there are now large numbers of people who were born or grew up in Latin America and who are now living in other countries around the world, there are many people with Chagas disease who may be unaware of their infection.

London has a large Latin American population. The total number of people with Chagas disease in London is not known, but it is thought that there may several thousand. Most of these people do not realise that they are at risk and so might never have been tested.
Testing for Chagas disease is readily available at the Hospital for Tropical Diseases.

In Latin America Chagas disease is spread by insects called triatomine bugs (also known locally as ‘vinchuca’ or ‘chirimacha’). They live in cracks in walls and in thatched roofs and usually bite at night. Less commonly, Chagas disease can be spread by drinking contaminated fruit juice, or by blood transfusion or organ transplantation. All blood products and donated organs are tested in the UK to reduce this risk. In a small proportion of pregnancies, the parasite can be passed to the baby by infected mothers. This is called congenital infection.

Immediately after becoming infected, a small number of people experience a mild illness with fever which gets better by itself. Most people have no symptoms at all and so do not know that they are infected.

The infection can then remain silent and most people experience no illness during their lifetime. However, one in three people can develop problems – with either their heart or their digestive system or both - after years or decades, and this is why detection and treatment of infection is important. The heart rhythm and pump strength might be affected. Symptoms can include breathlessness, ankle swelling, dizziness or collapse. Problems with the digestion such as difficulty swallowing or constipation can also occur.

The only way to know for sure whether you are infected is by having a blood test. Blood tests can be organised at the Hospital for Tropical Diseases, through GPs or the UK Chagas Hub’s community screening events.

If you come from Latin America, we advise you to inform your doctor:

  • If you arrive with Chagas disease already diagnosed. Your doctor will send you for specialist follow-up in a clinic.
  • If you have never had a Chagas test. You may have the infection and be well, so it is important to detect it before it causes harm.
  • If you are a woman and plan to have children. It is advisable to know beforehand if you have the disease to avoid transmitting it to your children as much as possible. If you are already pregnant and your baby gets the infection, it can be cured with the current treatment.

In the UK we treat Chagas disease with a drug called benznidazole. This is a tablet taken daily for a course of up to 60 days. Benznidazole can have side effects. These are usually mild and get better by themselves. They may include: 

  • Rashes
  • Nerve problems
  • Poor appetite and weight loss
  • Nausea and vomiting
  • Headache or dizziness
  • Problems sleeping

If your doctor wishes to prescribe benznidazole you will be given more information about possible side effects before you start treatment. You will also be closely monitored during your treatment so that any problems can be dealt with early.

The UK Chagas Hub has resources on their website and social media platforms:

Facebook/Twitter/Youtube: @UKChagasHub

Have you travelled to a tropical country in the last six to 12 months and are you acutely unwell? You can be seen in our emergency walk-in clinic Monday to Friday 9am-4pm.

Our travel medicine service offers specialist travel advice including for individuals with complex health conditions. We offer this on a privately and via NHS referral basis.

Please contact: or 020 3447 7999 for more information about our services.