Chagas - The Kissing Bug Disease

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Dogs and Scabies. Anderson Nascimento 2008

Chagas is a disease that doesn't get a lot of attention. But it's something we should know about. It has infected millions, probably at least 8 million, throughout Latin America. It's an infection that can come back years later to cause significant health problems after an unnoticed initial infection.

Chagas is in Texas.

The insect that spreads the infection can be in Texas - and in small numbers in other parts of the US, as north as Illinois.

There have been rare infections of people in Texas with Chagas - who have not traveled. One study of blood donors in Texas found 1 in 6500 had the infection in their blood. (It should be noted blood donors are screened for Chagas in the US since 2007). Another study of 17 Texans with the infection found that 6 had not traveled.

Kissing bugs, the insect which spreads the infection, are not common in the US. However, of Kissing Bugs found in Texas, many have been shown to have Trypanosoma cruzi (or T cruzi for short), the parasite that causes the disease. In one study in 10 counties in southern and central Texas found that of 40 Kissing Bugs, 73% had T cruzi and half of these had fed on humans.

A fair number of dogs have been infected; in one study, 9% of shelter dogs in every part of the state studied were positive for Chagas. In some parts of the world, having a dog is associated with increased chance of acquiring Chagas; in the US, however, the insect that spreads it is rare and so the risk is very low.

There are health officials that are concerned that this disease may become a risk for the people of Texas.

Most infections with Chagas were acquired elsewhere when individuals lived or traveled to parts of Central and South America. Medical care for these infections can be quite expensive. Each infection in the US is thought to cost over $90,000 in societal and healthcare costs.

It is thought Chagas medical bills and lost productivity total 800 million US dollars in the US alone. The disease is thought to cost the world 7 billion US dollars.

What are the symptoms?

There are 2 stages.

Acute Stage

  • immediately after infection
  • most do not have any notable symptoms; others with mild infection
  • last few weeks to months, usually 4-8 weeks without treatment
  • parasites can be found in the blood

Most symptoms are not very specific

  • tiredness
  • fever
  • swollen lymph nodes
  • enlarged liver or spleen
  • Others may have rash, loss of appetite, diarrhea, and vomiting. 

It is hard to distinguish this from other infections. There is, however, one sign that is very specific to Chagas. There may be swelling around the site where the parasite entered. Because this site is often on the face and infection often occurs through infected material entering into the eye, many develop one sided eye swelling in the acute infection stage. The one swollen eye - called Romaña's sign - is very much associated with the disease.

 

Very young children and infants may develop brain swelling. Pregnant mothers may lose their pregnancies. Most deaths in the acute phase occur in those who are youngest; mortality can be significant in congenital infection.

Chronic Stage

The chronic stage may become apparent years, often 10-20 years, after the initial infection. Some who are infected will have chronic symptoms. These can be serious, persist over years, and be life-threatening. This occurs in 20 - 30% of infected people. Early treatment can help, but is often not available or the infection is not recognized.

These complications can include heart, esophagus, or colon problems. Some may develop enlarged hearts that do not pump well and have abnormal rhythms, which may require electronic pacing or heart transplants. It may be an overlooked cause of heart disease. Others may have a dilated esophagus or colon which can lead to serious gastrointestinal problems.

Those with weak immune systems (from HIV, chemotherapy, or immunosuppressive drugs) are at more risk for reactivating the parasites.

Chronic infection in a pregnant mother does not lead to infection in infants.

What causes it?

The Kissing bug is to blame, actually. These bugs tend to bite faces - hence the name. These bites spread the parasite, Trypanosoma cruzi (T cruzi), which causes Chagas.

The triatomine bug - the kissing bug - becomes infected with T cruzi by feeding on infected blood from a person or animal. The bug then feeds on another person, spreading the infection through their bites. The bites alone don't create the infection, though. The bugs defecate near the site of their bite and bug excrement is what leads to the spread.  This is especially true if some scratches the wound or if the infected material enters mucus membranes on the face (such as the eyes, mouth, nose). These bites are usually on the faces of sleeping people. The bugs tend to come out at night when people are sleeping and hide in the roof or on the wall during the day.

The parasite once inside of a human being will then spread into cells. It then differentiates into a new form. The parasites subsequently are released into the blood, only to invade cells again.

What else causes it?

The parasite can also spread by other means

  • Blood Transfusions (The parasite can remain viable in blood at room temperature and down to 4 C. It is unclear whether transmission can occur from frozen blood)
  • Organ Transplantation
  • Breast Milk
  • Birth (and can lead to miscarriage and stillbirth)
  • Laboratory exposures
  • Food exposures have also occurred, through insects defecating on food or juice

Where is it found?

Those infected largely live in Mexico, Central America, and South America, where it is though 8 million have been infected. It's a disease of the housing of the poor. The Kissing Bigs hide in the adobe or mud walls and thatched roofs of those with fewer resources. Some areas, such as some parts of Bolivia where over 1 million are thought to have Chagas, have very high rates; as many as 30-40% of children are thought infected in some parts of Bolivia.

More than 300,000 people are presumed to be infected in the US. Very rarely does transmission occur in the US. Most infections occurred elsewhere and arrived through travel or immigration.

How is treated?

The medications for Chagas are very specific and not commonly used. In the US, these drugs need to be obtained through the CDC with special permission through a specialist consultation.

Not all practitioners will choose to treat all who've been infected; healthy adults with chronic infections are not always treated.

All with acute infection should be treated. Congenital infections and all infections in children should be treated. Those with weak immune systems and many other adults with chronic infections should be treated.

The symptoms of chronic infection may be severe. Heart transplants may be needed for the cardiac symptoms.

How is it diagnosed?

Chronic stages may be recognized by a doctor through recognition of the clinical signs and symptoms coupled with the risk factors involved.

Looking at blood under a microscope can identify T cruzi when it is in the blood, especially in initial infection. Many chronic infections do not have T cruzi in the blood and instead, the diagnosis is based on blood serologies

Can other animals be infected?

Yes, in fact, Chagas has been recognized in Texas through infections in pet dogs.

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