Assassin bugs, also known as kissing bugs, are a group of insects that can transmit a potentially fatal parasitic disease called Chagas disease to humans. Chagas disease is a major public health concern in many parts of Central and South America. This article provides an overview of assassin bugs and examines data on how many people have died from Chagas disease transmitted by these insects.
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What are Assassin Bugs?
Assassin bugs are true bugs that belong to the family Reduviidae. There are over 7,000 species of assassin bugs, most of which are predatory and feed on other insects or arthropods. However, some species, known as kissing bugs, feed on the blood of mammals, including humans. Kissing bugs get their name from their tendency to bite humans on the face or lips while they are sleeping.
The most common kissing bug species that transmit Chagas disease include:
- Triatoma infestans
- Triatoma dimidiata
- Triatoma protracta
- Triatoma sanguisuga
- Panstrongylus megistus
- Rhodnius prolixus
Kissing bugs require animal blood to survive and reproduce. They typically feed at night when humans and other mammals are sleeping. Using their piercing-sucking mouthparts, they bite the victim and ingest blood.
How Do Kissing Bugs Spread Chagas Disease?
Kissing bugs are able to transmit a parasitic protozoan called Trypanosoma cruzi to humans through their feces. This single-celled parasite causes Chagas disease (also called American trypanosomiasis).
Here is how transmission occurs:
- The kissing bug bites a human or animal and ingests blood.
- As it feeds, it simultaneously defecates near the bite wound.
- The feces contain the infectious form of T. cruzi parasites.
- The victim unintentionally rubs the feces into the bite wound or other open cuts.
- The parasites enter the bloodstream and infect the human.
Chagas disease can also be spread through:
- Congenital transmission (infected mother to baby)
- Blood transfusions
- Organ transplants
- Consumption of food contaminated with kissing bug feces
However, vector transmission via kissing bugs accounts for the vast majority of cases in endemic areas.
What is Chagas Disease?
Chagas disease, caused by the T. cruzi parasite, is a neglected tropical disease endemic to parts of Latin America. An estimated 6-7 million people worldwide are infected.
The acute phase of Chagas disease often goes unnoticed, as symptoms are usually mild and nonspecific, such as fever, fatigue, body aches, headache, rash, loss of appetite, and vomiting. Without treatment, the disease progresses to a chronic phase.
Over the course of decades, 20-30% of those infected develop potentially life-threatening complications such as:
- Cardiomyopathy – enlargement of the heart
- Gastrointestinal problems such as megacolon and megaesophagus
- Heart rhythm abnormalities
- Congestive heart failure
- Strokes and sudden death due to heart complications
There are some prescription drugs that can treat Chagas disease, such as benznidazole and nifurtimox. However, they are often ineffective at curing the chronic phase. Treatment is more likely to be successful if given soon after infection.
Where are Kissing Bugs Found?
Kissing bugs are primarily found in rural areas of Mexico, Central America, and South America. Areas with more primitive housing, such as those with thatched roofs, mud walls, and dirt floors, tend to have higher infestation rates.
Some species have expanded their range to parts of the southern United States. Triatoma sanguisuga and Triatoma protracta are native to the US and can be found in states like Texas, New Mexico, and Arizona. Two introduced species, Triatoma rubida and Triatoma gerstaekeri, have also been found in southern states.
However, the risk of vector-borne transmission remains very low in the US. Higher incomes, better housing conditions, and modern vector control practices help prevent kissing bug infestations and Chagas disease outbreaks compared to poorer regions of Latin America.
How Many People Die from Chagas Disease Each Year?
According to data from the World Health Organization, Chagas disease causes around 10,000 deaths per year worldwide. The vast majority of fatalities occur in poorer regions of Mexico, Central America, and South America that lack adequate prevention and treatment resources.
Below is a table showing the estimated number of Chagas disease deaths by region in 2016, the most recent global data available:
| Region | Estimated Deaths from Chagas Disease |
|---|---|
| Mexico, Central & South America | 9,722 |
| Rest of the World | 142 |
| Total | 9,864 |
A few key points:
- Over 98% of Chagas deaths occur in Latin American countries where the disease is endemic.
- Brazil sees the highest number of fatalities, followed by Mexico and Argentina.
- Bolivia has the highest mortality rate, with over 6 Chagas deaths per 100,000 population.
- Fatalities outside Latin America mostly occur due to chronic Chagas reactivating in immigrants.
The number of annual deaths has decreased in recent decades thanks to vector control programs and improved housing in urban areas. But Chagas remains a significant public health problem in poorer rural communities of Latin America.
Chagas Mortality Data in Select Endemic Countries
Here is a breakdown of the annual Chagas disease death toll in some of the hardest hit countries based on 2016 estimates from the WHO:
| Country | Estimated Annual Deaths from Chagas |
|---|---|
| Brazil | 3,000 |
| Mexico | 1,500 |
| Argentina | 1,300 |
| Colombia | 500 |
| Bolivia | 400 |
| Peru | 300 |
| Ecuador | 200 |
| Venezuela | 200 |
| Guatemala | 200 |
Brazil consistently has the most Chagas deaths because it has the largest overall population infected. Other populous countries like Mexico, Argentina, and Colombia also see high numbers of fatalities.
On a per capita basis, smaller countries like Bolivia and Paraguay are typically hit hardest. Rural communities in these countries have higher poverty rates, more primitive housing, and less access to healthcare.
Chagas Disease Deaths in the United States
In the US, vector-borne transmission of Chagas is extremely rare. The US sees less than 30 cases per year acquired locally through kissing bugs. And US cases virtually never progress to the fatal chronic stage due to access to healthcare and treatment.
However, there are some Chagas deaths each year in the US due to reactivation of chronic infections among immigrants from Latin America. The CDC estimates 300,000 or more people in the US may have chronic Chagas but many are undiagnosed. When their immune system is compromised, the dormant infection can reactivate.
A study published in The Lancet Infectious Disease journal estimated the annual number of Chagas deaths in the US at around 63. Most fatal reactivations occurred among older immigrants who acquired Chagas decades ago before coming to the US.
With more awareness and screening, timely treatment could prevent many of these deaths. But the death toll from chronic Chagas among Latino immigrants in the US remains significant.
Prevention and Control Strategies
Preventing vector-borne transmission of Chagas requires controlling kissing bug populations and avoiding contact with them in infested areas. Some key strategies include:
- Improving rural housing by fully plastering walls, screening windows/doors, and removing thatched roofs.
- Spraying insecticides inside houses and surrounding areas to kill bugs.
- Using bed nets and screens to provide a physical barrier.
- Keeping outdoor lights off at night to avoid attracting the nocturnal kissing bugs.
- Sealing cracks in floors, walls, and roofs to block entry points.
- Removing wood, rock, and garbage piles near houses that provide refuge for bugs.
In endemic areas, routine screening of blood donors, organ donors, and pregnant women can identify infections early and prevent transmission. Developing safer blood supplies has also reduced transfusions as a source of infection.
Treatment with antiparasitic drugs can cure acute Chagas disease and stop progression to the chronic phase. Increased access to healthcare and Chagas treatment programs are needed, especially in poor rural communities.
Conclusion
Chagas disease remains a highly neglected tropical illness afflicting millions in Latin America. Transmission most often occurs when triatomine kissing bugs infected with T. cruzi parasites bite humans. An estimated 10,000 people die from Chagas annually, predominantly in endemic countries like Brazil, Mexico, and Argentina.
Mortality is concentrated in poorer rural areas of Latin America where housing conditions, lack of vector control, and healthcare access perpetuate transmission. Expanding vector control programs, early detection, and access to antiparasitic treatment could significantly reduce Chagas deaths in coming decades.
In the US, the threat is mainly from reactivation in older immigrants with previously acquired infections. But locally-acquired vector transmission and deaths remain extremely rare due to higher living standards and modern housing.