Blood-sucking assassin bugs that cause Chagas disease can also transfer parasite DNA to humans. Once the DNA enters a person, they may pass it on to their children. Therefore, thousands of people today may have DNA delivered by insects in their permanent genetic makeup.
However, the assassin bug, or kissing bug, is not the only case where a parasite or virus shares its DNA with people.
The “human population may be a patchwork of all the organisms to which it has ever been exposed,” says scientist Mariana Hecht.
When an assassin bug infects a person, a microscopic sing-cell parasite, Trypanosome cruzi, enters the bloodstream. From there, the tiny parasite can infiltrate our genome, inserting its DNA into the host via horizontal gene transfer. These DNA segments, called transposons, can replicate themselves and move around within the genome.
“Once inside, the parasite genes can hop around, hitchhiking from one chromosome to another and leaving genetic chaos in their wake. They can even be passed on from one generation to the next. Hitching a ride aboard sperm and eggs, they can add themselves to the genomes of children, who’ve never been in direct contact with trypanosomes,” reported National Geographic.
After studying three Brazilian families with members suffering from Chagas, Hecht found 29 descendants had had trypanosome DNA in their genomes. Even so, the insects had never bitten the children.
DNA Delivered by Assassin ‘Kissing Bugs’
Assassin bugs, also called triatomine bugs or kissing bugs, invaded Latin America, infecting 8 million people with Chagas, caused by a parasite, Trypanosoma cruzi.
“The kissing bug usually feeds around a person’s face when the person is sleeping, which is how the insect got its name. After feeding, the bug defecates near the wound. People normally become infected when they rub that fecal matter into the wound or near the eye,” reports USA Today.
Up to 60% of kissing bugs may carry the parasite versus 0.1% of mosquitos. Fortunately, the bugs may need hundreds or more bites before they deliver the parasite to humans. Like bed bugs, assassin bugs may establish a colony in a home, allowing more opportunities to bite.
Unfortunately, Chagas disease affects the heart and digestive system and, like insect DNA, can pass from mother to child. In chronic cases, symptoms can last a lifetime, but they will respond to treatment if caught early.
According to the CDC, around 300,000 people in the United States live with the chronic, painful, and sometimes deadly disease. Notably, only a very few of the cases in the US come from Kissing bug bites that happened inside the country. Mostly, the bites happen in impoverished tropical areas.
Often, people are unaware of any infection, and it can take decades for symptoms to show.
On the other hand, according to USA Today, the sightings of the kissing bugs are going up in some states.
“Kissing bugs are commonly found in South and Central America, and Mexico, but doctors are starting to count cases in states like Texas, Arizona, Arkansas, Louisiana, Mississippi, Tennessee, Utah, and California, according to a Texas A&M University program studying Chagas disease.”
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Sandflies and Another Deadly Parasite
Recent research in Brazil indicates that sandflies are attracted to the smell of dogs infected with another parasite called Leishmania infantum. Somehow, it appears the parasite can change the odor of its host to appeal specifically to female flies. Notably, only the females feed on the blood of dogs and humans.
Once the sandfly bites the infected dog, it can carry the parasite to other hosts, like people. From there, a potentially deadly disease called Visceral leishmaniasis causes skin sores and can infect organs. Each year, hundreds of Brazilians die from the disease. Worldwide, the disease may kill between 20,000 to 40,000 people each year.