Updated: Thursday November 26, 2015 : 10:43 EST
Abstract:
There has been a recent surge in news related to Chagas Disease and the Kissing Bug, most referring to recent reports by the CDC. CDC has not issued a press release on this topic and its information pages on Chagas disease and the Triatomine Bug have not been updated since 2013. We will update this article if and when new information becomes available.
Main Article:
A disease that was previously seen primarily in Latin America is making its way north. Chagas Disease (American trypanosomiasis) is a parasitic infection that, untreated, can lead to cardiac, digestive and neurological disorders and death.
Chagas disease is caused by the Trypanosoma cruzi (T. cruzi) parasite, which is found in the feces of a species of insects called Triatomine. This nocturnal bug is sometimes called the “kissing bug”, because it usually bites its sleeping victim around the mouth or neck. After the bug bites and ingests blood, it defecates on the person, potentially leaving behind the T. cruziparasites. The parasites can then enter the host through an open wound or through the any of the mucous membranes (e.g., nose, eyes, mouth).
AFTER THE BUG BITES AND INGESTS BLOOD, IT DEFECATES ON THE PERSON, POTENTIALLY LEAVING BEHIND THE T. CRUZI PARASITES
Transmission of the parasite can also occur during childbirth, blood transfusions and organ transplants where the donor is infected. Animals can also be infected.
Many people who carry the parasite may do so for years without any symptoms. In about half of all cases, the first sign of infection will be a swollen eyelid, sometimes accompanied by fever, headache, swollen glands and abdominal pain. During this “acute” phase of the disease, a high number of parasites are circulating in the blood. In the second, “chronic” phase, the parasites are found mainly in the heart and digestive muscles. This phase can be fatal. It is important to note, however, that not all infected people get sick. In fact, according to the University of Arizona Kissing Bug Project, only 10% of infected people will get sick after 30 years of initial contact.
Treatment for Chagas disease is typically treated with the antiparasitic drugs benznidazole and nifurtimox. Both drugs can cure Chagas disease, if the infection is treated early. The efficacy of the treatments diminishes the longer the patient has been infected.
Prevention measures are focussed on avoiding getting bitten by the kissing bug and avoiding transmission through blood, organ and tissue donations. There are currently no vaccines or drugs that will prevent the disease. The World Health Organization recommends spraying kissing bug-infested homes with a residual insecticide, sleeping with bed nets and doing home improvements, such as installing window screens and sealing of cracks and holes that could let the bugs inside. In addition, blood screening for the T. cruzi parasite should be performed on all blood, organ and tissue donors, as well as on pregnant women and newborn infants to ensure early diagnosis and treatment.
Chagas disease is endemic in Latin America and the WHO estimates that 6 to 7 million people are infected worldwide. It is considered to be a “disease of poverty”, due to the fact that impoverished housing conditions make kissing bug infestations difficult to control, and those who have typically become ill with the disease do not have adequate access to healthcare.
The Centers for Disease Control and Prevention is reporting that the kissing bug has been spotted in at least 28 states in the US and that more than 300,000 people in the country are infected with Chagas disease.
References:
Centers for Disease Control and Prevention (2013, November 29). “American Trypanosomiasis”. Retrieved from http://www.cdc.gov/dpdx/trypanosomiasisAmerican/
Centers for Disease Control and Prevention (2013, July 19). Triatomine Bug FAQs. Retrieved from http://www.cdc.gov/parasites/chagas/gen_info/vectors/
Univerisity of Arizona. “Basic Kissing Bug Facts”. Retrieved from http://neurosci.arizona.edu/kissingbugs/basicfacts
World Health Organization (2015, March). “Chagas Disease” [Fact Sheet]. Retrieved fromhttp://www.who.int/mediacentre/factsheets/fs340/en/
Raymond Whitham, DrMéd, DrMédVét, MPH
The insect vectors for Trypanosoma cruzi are many (approximately 100). They all are members of the sub-family Triatominae of the Reduviidae family of insects. Only some of them are major vectors for humans.
Trypanosoma cruzi infects mammals. Chagas’ disease has been in the Americas for millions of years, including North America. It is present in wildlife throughout South, Central, and the USA, and Mexico.
It is transmitted via Triatominae contaminated feces as described in the article but also by mouth via contaminated food with contaminated Triatominae feces, mother to fetus, and blood transfusions. The inflammation of the eyelid described in the article occurs when contaminated Triatominae feces get into the eyes.
Human transmission usually occurs in dwellings with a large infestation of Triatominae in poor rural areas of South and Central America and Mexico. The infestation is worsened by wild and peridomestic mammals (opossums +++) and their Triatominae that feed on them in hidden places of the house. People in the USA are less tolerant of wild animals and insects in their house.
My veterinary thesis/dissertation provides an in depth account of the epidemiology of Chagas’ disease (in French). Anyone who would like a copy can download it at:
http://theses.vet-alfort.fr/telecharger.php?id=1158
Corrected version of my post
The insect vectors for Trypanosoma cruzi are many (approximately 100). They all are members of the sub-family Triatominae of the Reduviidae family of insects. Only some of them are major vectors for humans.
Trypanosoma cruzi infects mammals. Chagas’ disease has been in the Americas for millions of years, including North America. It is present in wildlife throughout South & Central America, the USA, and Mexico.
It is transmitted via contaminated Triatomine feces as described in the article but also by mouth via contaminated food with contaminated Triatomine feces, mother to fetus, and blood transfusions. The inflammation of the eyelid described in the article occurs when contaminated Triatomine feces get into the eyes.
Human transmission usually occurs in dwellings with a large infestation of Triatominae in poor rural areas of South and Central America and Mexico. The infestation is worsened by wild and peridomestic mammals (opossums +++) and their Triatomines, that live in hidden places of the house, feed on them. People in the USA are less tolerant of wild animals and insects in their houses.
My veterinary thesis/dissertation provides an in depth account of the epidemiology of Chagas’ disease (in French). Anyone who would like a copy can download it at:
http://theses.vet-alfort.fr/telecharger.php?id=1158