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Geography in the News: Chagas Coming

By Neal Lineback and Mandy Lineback Gritzner, Geography in the NewsTM

CHAGAS: THE KISSING BUG’S DISEASE

Recent news releases have highlighted some of the exotic animals infesting the United States. These include fire ants in the Southeastern United States, African “killer” bees in the Southern border states, the snakehead fish in Maryland and 10-foot (3 meter) Burmese pythons in the Florida Everglades. Each of these is non-native to the United States, making it an exotic species in this country. There is, however, an exotic South American bug now present in this country that carries a dangerous disease called Chagas.

Chagas (SHA-gus) disease, first described by Brazilian physician Carlos Chagas in 1909, is caused by a microscopic parasite called Trypanosoma cruzi (T. cruzi), carried by a tiny beetle vector, which transmits the disease to humans. This beetle’s name is vinchuca, but in parts of South and Central America it is known as “the kissing bug.” Vinchucas may bite rodents and dogs which serve as reservoirs of the protozoan T. cruzi. Then humans may be infected when the vinchucas bite them.

811_NGS_Chagas

Generally, vinchucas are drawn to sources of carbon dioxide released from sleeping humans’ mouths and noses-hence the name “kissing bug.” When vinchucas bite humans around the mouth, they can leave feces infected with T. cruzi which may enter the skin through any open wound. Although the kissing bug is the primary cause of infection within most of the native ranges of T. cruzi, transmission is also possible through other means, including blood transfusions, organ transplants, breastfeeding and by congenital transmission. In Bolivia in 1992, for example, more than 17 percent of a group of blood donors were found to have serological markers for T. cruzi, which meant that they currently had Chagas disease or had been infected with the disease in the past.

Chagas infection may result in little or no early symptoms, with only a small percentage of the infected persons showing mild fever and slight swellings around the infection site. Severe heart and intestinal problems may not show up for 10-40 years, but then can be deadly. This gradual onslaught of the disease may cause those infected to believe their disabilities simply to be the normal aging of their bodies.

There is treatment for infected individuals, but it should be administered early in the disease’s development. This drug can totally eliminate the Chagas parasites in about 60 percent of the cases, but the best success comes in treating children. In the developing countries, the blood tests necessary to diagnose Chagas disease, however, are not often available. An estimated 16 to 18 million people worldwide are infected, virtually all in the Western Hemisphere. There is currently no vaccine available to prevent Chagas disease.

Most preventive efforts include heavy insecticide spraying of houses, particularly in poor rural areas. Recommendations to most travelers to infected areas are to avoid sleeping in buildings or outside in endemic areas without the use of fully enclosable, insecticide-impregnated bed nets.

Currently, Chagas disease is endemic in Argentina, Belize, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname and Venezuela. Keeping detrimental exotic species, such as the vinchuca, out of the United States is a near impossible task. One vinchuca was even found in a child’s crib in Tennessee in 1998, giving credence to the fact that the vector for Chagas disease is already here. At least five indigenous cases of Chagas disease have been diagnosed in humans, with at least three reported deaths from the disease. There may be many more unsuspecting victims with the disease.

Americans are much more aware of the impacts of exotic species recently, thanks largely to the media and to scientific analysis of worldwide data. Now that the vinchucas are here, scientists hypothesize that climate variability and other conditions may expand the vector’s range within North America.

Although little is specifically known about the sources of the vinchuca in the United States, immigration and imported goods from South and Central America are suspected original sources. As we have learned from a myriad of transplanted exotic animals and plants in the United States, political borders are no barriers to the movements of animals or diseases.

And that is Geography in the NewsTM

Sources: GITN 637, “The Snakehead Fish: Exotic on the Move,” August 16. 2002; Centers for Disease Control website, Health Information for International Travel, 2005-2006, “American Typanosomiasis (Chagas’ Disease)”; http://www.nationmaster.com/graph-t/mor_cha_dis; and http://www.cdc.gov/parasites/chagas/gen_info/index.html

Co-authors are Neal Lineback, Appalachian State University Professor Emeritus of Geography, and Geographer Mandy Lineback Gritzner. University News Director Jane Nicholson serves as technical editor. Geography in the NewsTM  is solely owned and operated by Neal Lineback for the purpose of providing geographic education to readers worldwide.

 

Comments

  1. James Ricci
    United States
    September 13, 2013, 1:25 pm

    Great article! Few people recognize that Chagas is as serious a threat as it is, and fewer realize that it is found in the United States, Just a few points of clarification:

    -Kissing bugs are not beetles, but true bugs (Hemiptera: Reduviidae) in the Triatominae.

    -Kissing bugs do not transmit T. cruzi by biting humans. Instead, the bug defecates while feeding, and the feces is laden with infective T. cruzi. The human is only infected once the infective feces is rubbed into the bite or other break in the skin (usually by scratching).

    -Chagas has been endemic to the southern US for as long as I am aware, but the reason it is not transmitted between humans here is due to the bugs themselves. The US kissing bugs that carry Chagas defecate after they have left the host, not while feeding, so the infective feces is not rubbed into human host. The only way a human is infected, then, is by eating something with the feces on it or somehow coming into contact with the feces. That being said, Chagas does pop up in other US animals occasionally, usually due to the animal eating an infected kissing bug.

  2. Dr. Stephen E. Hawthorne
    Potosí, Bolivia
    August 25, 2013, 5:38 pm

    I’ve been working since 1989 as a Family Physician in Bolivia where Chagas’ is endemic – sorry to see no data from here was available for your map! Just one correction: the vinchucas don’t locate humans by their carbon dioxide but by their body temperature. Their antennae have sensitive heat sensors. Because they are photophobic, the insects emerge at night from the cracks in walls or roofs where they hide during the day. They locate people in the dark when they are sleeping with covers up to the neck, which is why bites are usually on the face.

  3. Neal Lineback
    August 19, 2013, 4:12 pm

    Yes, but CDC has listed Chagas as one of five neglected parasitic diseases in the United States, targeted as priorities for public health action based on the number of people infected, severity of the illnesses, and our ability to prevent and treat them. Indeed, chagas may not be technically endemic in the United States, but the number of cases appears to be on the rise. Having spent a small amount of time in a rural village in Bolivia with my daughter and son-in-law when they were Peace Corp Volunteers, my advice is to pay attention to this disease even in this country and particularly in the poorest neighborhoods where sanitation is the lowest. The vinchuca beetle carrying the parasite T. cruzi is “secretive” and only comes out at night to do its damage, then retreats out of sight.

  4. Rick Tarleton
    United States
    August 19, 2013, 1:59 pm

    Chagas disease and the bugs that carry the parasite Trypanosoma cruzi that causes the disease have been endemic to the southern US for centuries – these are not new arrivals nor particularly exotic. Many animals besides humans are infected by T. cruzi – and this is the case in the US as well where domestic dogs but also many non-domesticated species (racoons, opposums, rodents, etc.). Humans are less often infected in the US because houses in the US are rarely infested by the insects.