Friday, September 30, 2016

The not-so-loving kissing bug

As fall approaches and the weather begins to cool from the stifling heat of summer, we all like to spend a bit more time outside enjoying the air. Unfortunately, this is the perfect time for insects who like to feed on our blood and potentially carry disease to come out and join us. Most people think of ticks and mosquitoes when they think of insects that carry disease, but there is another major player in the Americas: the Triatominae, also known as the kissing bug. This little creature can carry a parasite known as Trypanosoma cruzi, which causes Chagas disease.

Image result for the kissing bug
The Triatominae insect, aka the kissing bug, that
can carry the Trypanosoma cruzi parasite that
causes Chagas disease.
Image from
Chagas disease is a major global health threat, with 70 million people at risk of exposure and approximately 5.7 million people becoming infected each year. The disease mainly affects Latin America, but thanks to population flows and increases in vector populations, the disease has been spreading to the north, with cases reported in the US in Texas, in Canada, and even in Europe. The disease exists in two phases, the acute phase and the chronic phase. During acute infection, there are large numbers of parasites in the blood, but symptoms are few and non-specific. There can be fever, headache, swollen lymph nodes, or even completely asymptomatic cases. As the disease transitions into the chronic phase, the parasites sequester into the muscle of the heart and digestive tract. This can result in severe cardiac and digestive disorders, which can last for years after the original infection began. Most dangerously, heart failure can result, causing death.

Treatment for Chagas disease remains a major issue. There are very effective treatments for the acute phase, with almost 100% efficacy, but these treatments are underutilized. Treatment requires rapid diagnosis of the disease, which is often difficult due to the non-descript or non-existent symptoms. Also, the drugs need to be administered over a very long duration, 60-90 days, leading to low follow-through rates for treatment to completion. Unfortunately, there are currently no treatments for the chronic phase.

Current work being done at the University of Georgia is working to address one of these problems. They are focused on developing affordable diagnostic tests that can be used anywhere to diagnose Chagas disease in the acute phase. Their efforts focus on increasing the number of T. cruzi antibodies being detected in the test in order to allow for a more sensitive test. Not only will the test help identify people who have the disease, but it will also improve the ability to monitor how well a person is responding to treatment, hopefully allowing for decreases in treatment times.

Beyond the work at the University of Georgia focusing on improving diagnostics, there has also been a lot of effort into developing new treatments for Chagas disease. The Drugs for Neglected Diseases Initiative has chosen Chagas as one of their focus diseases and has been working on new therapeutics to treat both the acute and chronic phases of disease. Their goal is to develop an orally administrated treatment that will require less than 30 days of administration by 2020. They have moved into a Phase II proof of concept study with two different treatment options, with results expected late this year and early next year.

While advances are being made in detection and treatment of Chagas in humans, there are also many animals that are threatened by this disease. Chagas disease can also affect both wild and domestic animals, making elimination of the parasite reservoir impossible. Notably, Chagas disease in dogs is known to be frequently fatal, causing the same heart failure and cardiac symptoms seen in humans with chronic Chagas disease. For dogs, there is currently no available treatment for the disease. 

The best way to deal with Chagas for the time being is the prevent it. Insecticide spraying is encouraged by the World Health Organization and has been shown to decrease the incidence of disease. Also, being able to identify the Triatominae insects when they are seen can help people avoid areas where they could become susceptible to being bitten. These bugs are known to enjoy living in hay, woodpiles, and under porches, so avoiding these areas can help reduce transmission of the parasite. 

To protect yourself and your furry friends this fall, be sure to be on the lookout for the kissing bug. One kiss from this little love bug may just be your worst first date ever.  

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