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Chagas
The "Kissing Bug" Disease
Chagas disease (T. cruzi) was named after a Brazilian physician, Carlos Chagas, who first discovered the disease (1909). It is caused by the parasite Trypanosoma cruzi. Chagas disease is transmitted to humans and animals by insects and is mainly found in the Americas. The State of Virginia has been testing residents and finding an increasing number of people are infected.
It is estimated that as many as 8 million people in Mexico, Central America, and South America have Chagas disease, with most not knowing they are infected. Infection is lifelong and can be life threatening. The CDC estimates over 300,000 people in the U.S are infected. The World Health Organization reports 11,000 people die each year from Chagas disease.
In the United States and in other regions where Chagas disease is now found, control strategies are focusing on preventing transmission from blood transfusion, organ transplantation, and mother-to-baby (congenital transmission).
THE KISSING BUG- People can become infected in various ways. The main way is through vectorborne transmission. The insect vectors known to carry Chagas are called triatomine bugs. These blood-sucking bugs get infected by biting an infected animal or person.
Once infected, the bugs pass T. cruzi parasites in their feces. Bugs are found in houses made from various materials, including wood, straw and mud. During the day bugs often hide in small crevices in the walls and roofs. At night, when people are normally sleeping, the bugs emerge.
The triatomine bugs tend to feed on people's faces, which is why they are also known as "kissing bugs." After they bite and ingest blood, they defecate on the person.
A person can become infected if T. cruzi parasites in the bug feces enter the body through mucous membranes or breaks in the skin. The unsuspecting, sleeping person may accidentally scratch or rub the feces into the bite wound, eyes, or mouth.
People also can become infected through:
- congenital transmission (from a pregnant woman to her baby);
- blood transfusion;
- organ transplantation;
- consumption of uncooked food contaminated with feces from infected bugs; and
- accidental laboratory exposure.
It may not be safe to breastfeed if the mother has Chagas disease. However, Chagas disease is currently not known to be transmitted from person-to-person, or through casual contact with infected people or animals.
PREVENTION- Improved housing conditions and spraying insecticide inside to eliminate triatomine bugs has significantly decreased the spread of Chagas disease. Screening of blood donations for Chagas is another way to help prevent transfusion-acquired disease. Early detection and treatment of new cases, including mother-to-baby (congenital) cases will also help.
SYMPTOMS- Chagas disease has two phases, an acute and chronic phase. Both phases can be symptom free or life threatening.
EARLY STAGE- The acute phase lasts for the first few weeks or months of infection. It may not be noticed if the patient is symptom free or exhibits only mild symptoms and signs. Symptoms can include fever, fatigue, body aches, headache, rash, loss of appetite, diarrhea, and vomiting.
Physical exams may show mild enlargement of the liver or spleen, swollen glands, and local swelling (a chagoma) where the parasite entered the body. The most recognized marker of acute Chagas disease is called Romaña's sign, which includes swelling of the eyelids on the side of the face near the bite wound or where the bug feces were deposited or accidentally rubbed into the eye.
When symptoms develop during the acute phase, they may fade within a few weeks or months. If untreated, or when not successfully treated, the infection persists. Young children (<5%) can die from severe inflammation/infection of the heart muscle (myocarditis) or brain (meningoencephalitis).
The acute phase can be severe in people with weakened immune systems.
CHRONIC STAGE- The infection may remain silent for decades or even for life. However, some people develop:
- cardiac complications, which can include an enlarged heart (cardiomyopathy), heart failure, altered heart rate or rhythm, and cardiac arrest (sudden death); and/or
- intestinal complications, which can include an enlarged esophagus (megaesophagus) or colon (megacolon) and can lead to difficulties with eating or with passing stool.
TREATMENT-
Although treatment can be administered, it is not always successful. Approximately 1/3 of those infected can develop heart disease or megacolon, and can die from what appears to be sudden heart attacks.
Treatment includes antiparasitic treatment, to kill the parasite; and symptomatic treatment, to manage the symptoms and signs of infection.
Antiparasitic treatment is most effective early in the course of infection but is not limited to cases in the acute phase. In the United States, this type of treatment is available through CDC. Your health care provider can talk with CDC staff about whether and how you should be treated. Most people do not need to be hospitalized during treatment.
Symptomatic treatment may help people who have cardiac or intestinal problems from Chagas disease. For example, pacemakers and medications for irregular heartbeats may be life saving for some patients with chronic cardiac disease.
*In the U.S., medication for Chagas is available only through CDC. Your health care provider can talk with CDC staff about whether and how you should be treated.
The two drugs used to treat infection with Trypanosoma cruzi are nifurtimox and benznidazole. In the United States, these drugs are not FDA approved and are available only from CDC under investigational protocols. For both drugs, side effects are fairly common, and tend to be more frequent and more severe with increasing age.
Common side effects of benznidazole treatment include:
- allergic dermatitis
- peripheral neuropathy
- anorexia and weight loss
- insomnia
The most common side effects of nifurtimox are:
- anorexia and weight loss
- polyneuropathy
- nausea
- vomiting
- headache
- dizziness or vertigo
Contraindications for treatment include severe hepatic and/or renal disease. As safety for infants exposed through breastfeeding has not been documented, withholding treatment while breastfeeding is also recommended. The following table outlines recommended dosage regimens by age group:
Questions regarding treatment should be directed to Parasitic Diseases Public Inquiries (404-718-4745; e-mail chagas@cdc.gov).
For emergencies (for example, acute Chagas disease with severe manifestations, Chagas disease in a newborn, or Chagas disease in an immunocompromised person) outside of regular business hours, call the CDC Emergency Operations Center (770-488-7100) and ask for the person on call for Parasitic Diseases. More information here.
Kissing Bug
Triatomine
All triatomine species are potential vectors of the Chagas disease parasite.
"Most triatomines aggregate in refuges during day and search for blood during night when the host is asleep and the air is cooler. Odors as well as heat guide these insects to the host. Carbon dioxide emanating from breath, as well as ammonia, short chain amines and carboxylic acids from skin, hair, and exocrine glands from vertebrate animals, are among the volatiles that attract triatomines. Vision also serves triatomines for orientation. During night, adults of diverse species fly to houses attracted by light.
Adults produce a pungent odour (isobutyric acid) when disturbed, and are also capable of producing a particular sound by rubbing the rostrum over a stridulatory sulcus under its head (stridulation)." [Source- WIKI]
For more information, July 2014, click here.
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