Thursday, June 14, 2012

A Kiss to Avoid

Conenose bug- MObugs- Shelly Cox
Merrill Dubach sent me a picture of a smashed bug which had bitten his granddaughter's leg.  He suspected the bug, now dead, was a "kissing bug" and asked if it could infect her.  The pictures he sent weren't enough to identify the bug, but it certainly was in the Reduviid family as are kissing bugs.  If you Google "kissing bug disease" you quickly find more than enough to scare you about Chagas disease, but understanding the meaning to us in Missouri takes a little more time.

Kissing bugs are members of the Reduviid family of insects, commonly known as assassin bugs.  Most assassin bugs shove their proboscis into insects, inject their digestive juices and then suck up their predigested dinner.  When handled they may use these this as a weapon of self defense, but they otherwise aren't interested in mammals.

One species of kissing bug- Wikimedia
The "kissing bugs" belong to the same family but the Triatominae subfamily live by sucking mammal's blood.  They get their name from the habit of biting sleeping victims around the lips and eyes.  Their reputation is greatly enhanced by the transmission of Chagas disease.  This is a very common disease in rural areas of Central and South America.  After initial symptoms, it remains dormant in most patients, providing a pool of the parasite for other kissing bugs to feed on and spread it further.  A portion of the infected people go on to develop fatal complications.

Scary stuff, but not a big concern in the United States so far.  There have only been seven documented cases of Chagas disease acquired within our borders.  It is most common in the southern states, but according to new research it may become a greater problem in the future.  A study recently reported by the National Science Foundation suggests that climate change may increase our exposure to the parasite.
"A new study finds that 38 percent of kissing bugs collected in Arizona and California contained human blood, and that more than 50 percent of the bugs also carried the parasite that causes this life-threatening disease. This upends the view that U.S. kissing bug species don't regularly feed on people and suggests that Chagas could spread, driven north by climate change."
The risk of increasing Chagas disease exposure could come from a northern movement of kissing bug populations.  As they infect more vectors, i.e. humans and other mammals, that then provides an expanding pool of the parasites for the next generation for kissing bugs to feed upon.  We don't have a large population of people sleeping in jungle huts that are exposed to nighttime feeding bugs so the frequency is unlikely to reach high levels.

The odds of increased cases of Chagas disease in the US are unknown at the present.  The risks from an individual kissing bug bite in Missouri are relatively low, but just as your momma said, be careful who you kiss.


You can see pictures of some of the many species of Triatominae at bugguide.net.
See also this MOBugs link.

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