Nebraska woman finds parasitic cattle worms in her eyes after running through swarm of flies
Living in the vicinity of cattle or running face-first into a swarm of flies in a rural area could put people at risk of contracting the parasite, says the report
Holidaying in California, a 68-year-old woman from Nebraska ran through a swarm of flies and little did she know that the encounter would turn into a nightmare. Her right eye became a breeding ground for parasitic worms called Thelazia gulosa, making it only the second such infection by the species in humans, according to the Centers for Disease Control and Prevention (CDC) report.
The eye worm, which spreads by flies and feeds on tears, is no stranger to the US. Found throughout Northern US and Southern Canada, it has shown to infect cattle but infections in humans were unheard of until a little over two years ago.
"This is only the 11th time a person has been infected by eye worms in North America," explained lead author Richard Bradbury, who is the team lead for the CDC's Parasite Diagnostics and Biology Laboratory. "But what was really exciting it that it is a new species that has never infected people before. It's a cattle worm that somehow jumped into a human," says Bradbury.
The first case
The first victim of the cattle worm was a woman from Oregon, who pulled out a translucent, wiggling worm — nearly a half-inch-long — from her eye. She complained of an irritated and red eye, with bouts of migraine too.
As the victim received treatment, some of the worms were parcelled to CDC for identification. "We immediately thought it could be Thelazia californiensis because that is the only species that was known to infect humans in the US. It was only after we looked more carefully that we realized some differences in anatomy that meant it could not be Thelazia californiensis. We had to go back to papers published in German back in 1928 to help identify this worm as Thelazia gulosa." says Bradbury.
After further analysis, the CDC realized that the worm belonged to a species that had never been reported in humans before. It was a species of the Thelazia eye worm. "Previously, it was thought that there were only two different species of these (Thelazia) eye worms that infected humans worldwide. Now, we have to add Thelazia gulosa, a third one to the list," says Bradbury.
This infection called thelaziasis can be caused by all the three species and it presents itself as conjunctivitis in humans, says the CDC report. The cattle eye worm is endemic to Europe, Asia, and Australia, as per the report. Previously, they say, the worm was once seen in California, when it caused an infection in a giraffe imported from Namibia in 1970.
The woman's eye hosted 14 worms, totally. She was not put on anti-parasitic treatment because doctors worried that her eye could end up lodging dead parasites, reports CNN. Only after she got rid of the 14 worms, her nightmare was over. Her vision remains good, with no other complications, as per CNN.
According to Bradbury, symptoms typically resolve after the worms are removed. But the worms could cause scarring of the eye and even blindness if they manage to move across the surface of the eye.
The next victim
After two years, these worm found another victim — but this time in California. The woman removed four worms from her eyes and was put on antibiotics.
Like the previous time, this was brought to CDC's notice. Analysis revealed that the same cattle worm behind the attack. In the report, the researchers warn that people should get immediate medical help if they find these worms squiggling around in the eye.
"In reported cases where the infesting nematodes have been removed from the eye within one to two months of first observation, the associated conjunctivitis has resolved and no long term clinical effects have been observed," says the report.
So far, the researchers know that living in the vicinity of cattle or running face-first into a swarm of flies in a rural area — as seen in the first and the second patients — could put people at risk of contracting the parasite.
What we don't know yet?
While it is known that the worm spreads between animals through flies, the research team does not yet understand why the cattle-infecting worms have taken an interest in humans.
"Monitoring of thelaziasis in cattle does not occur, and therefore it cannot be determined if there is an increasing prevalence of T. gulosa infections among domestic cattle which is resulting in zoonotic spillover events into humans and other unusual hosts. Renewed surveillance studies on domestic and wild ruminants would assist in better elucidating the situation in those hosts and would indicate what regions of the United States further human infections might occur in," says the report.