En Strålande Utsikt

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Forgotten Disease: Chagas | (part 2/13)

So, I am going to try to convey some of the more common among the ‘forgotten diseases’ in the world in a manner that I myself can understand them. They are the tropical diseases that e.g. Médecins Sans Frontières and the WHO fight, but where there is no money to gain and hence no Big Business is to find treating them. Today, I present the forgotten disease Chagas Disease.

Chagas Disease: Trypanosoma cruzi

Chagas is caused by the parasite (protozoa) Trypanosoma cruzi which is transferred by the blood-sucking reduviid bug (T. cruzi is related to the trypanosome parasite that causes sleeping sickness [a topic for another day] in Africa), found primarily in South and Central America, but lately it has spread to the US (once again showing the importance that the minority world starts treating majority-world ills). The bug bites the skin and leaves infected ‘waste’ that spreads the protozoa from the bug to the human and infects tissues and the blood when one e.g. rubs eye, nose or scratches the wound. It is also communicated via food, blood, or mother-to-child during pregnancy. Note: the bug is a vector, i.e. it carries the protozoa but does not per se cause the disease.

Sickness

The progress is mainly two-fold, one acute and one chronic. The acute phase lasts for two months, and has few or none, but could be varied, symptoms e.g. oedema in lower limbs and face, headache, diarrhoea or chest pain and even heart failure (depends on the inoculation site). The chronic phase is induced as the parasites targets tissues and stay there, according to the WHO especially the heart and digestive smooth muscles. Most patients will be asymptomatic (have no signs of the disease), but in 30% of the cases it is signalled by cardiac symptoms e.g. arrhythmia, heart failure and thromboembolism (thrombocytes/blood platelets clog up artery) although these symptoms might take up to 20 years to develop. In 10% of the cases, digestive symptoms or mixed (e.g. digestive and cardiac) show as e.g. enlargement of colon or oesophagus, leading to difficulties swallowing and thus malnutrition. Mortality is higher for children, older people, immunocompromised, or where the parasite inoculum (number of bacteria) was high. The disease might take many years to show if the bacteria stay latent until it develops into symptoms (reactivation, as AIDS).

Detection

Physical examination may reveal symptoms. Examples of signs: enlarged liver, spleen, and lymph nodes, arrhythmia (irregular heartbeat) or tachycardia (rapid heartbeat). Testing may include: blood culture, chest x-ray, ECG (electrocardiogram) or peripheral blood smear (when in acute phase, highest number of parasites; can use malaria films).

Prevention

There is no vaccine, but some factors can be controlled. Improved housing, insecticide spraying, and personal hygiene reduce the risk of infection. Congenitally, one screens pregnant women for the disease and screen their babies at 8 months of age, and the use of gloves, laboratory coats and even face masks, or at least glasses, can stop spreading in the hospitals. Since improving housing and hygiene often are not available options for people living in extreme poverty, eliminating the disease is today virtually impossible.

Treatment

Chagas is treatable and treatment is needed especially in the acute phase due to the disease’s immunosuppressing ability – if untreated, the parasite will live on in the patient’s body. An anti-parasite treatment cure about 100% of the patients . However, side effects could be severe, so one must weigh the possibility that an infected patient might not develop the disease against the risk for uncomfortable or dangerous side-effects. Two drugs are used in particular: benznidazole and nifurtimox, having e.g. renal failure and miscarriage as side-effects. Nifurtimox also has neurological effects, either psychiatric or disorders (disorders being normally headaches or dizziness, appetite loss, and skin rashes but more severely e.g. seizures and neuropathy). Screening of donated blood prevents spread through donation. The older the person, the worse the side effects.

Why dangerous?

  • 30% of the patients get cardiac symptoms, hence potentially deadly, and overall the disease is affecting many of the body’s  most vital systems (digestive,cardiac, central nervous).
  • Is spread by bugs, hence very difficult to stop (think malaria…) and there is no vaccine.
  • Overall: you do not want to get bit because there is a 10% risk you will have problems eating, 30% of developing heart problems or neurological problems, and the 60% chance that you will not develop Chagas immediately still means the parasite remains in your body for 20 years…
  • …and even if you treat the disease the drugs have severe side effects that make you tired, cause your liver to fail or might even cause seizures.
  • It has been called the new AIDS, which is an inaccurate description because we can treat Chagas Disease – that is the main point, here: Chagas Disease is treatable.

***

Sources

http://www.who.int/neglected_diseases/diseases/chagas/en/index.html

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002348/

http://www.nlm.nih.gov/medlineplus/chagasdisease.html

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