What's Causing Florida's Leprosy Cases?
Armadillos can transmit the disease to humans, but the Florida Department of Health hasn't tested the strains in the nine patients to see whether they match those found in area armadillos.
Leprosy is often thought to be an ancient disease, but leprosy-causing bacteria continue to infect people in the southern United States, including in Florida, where nine people have been diagnosed with the disease so far this year.
What's to blame? It could be the nine-banded armadillo (Dasypus novemcinctus) that roams wild across much of the Southeast, experts say.
"Keep your distance from armadillos," said Dr. William Schaffner, an infectious-disease specialist at the Vanderbilt University Medical Center in Nashville, Tennessee, who wasn't involved in the Florida cases. "Don't play with them, don't eat them and don't keep them as pets." [10 Deadly Diseases That Hopped Across Species]
The cause of the Florida cases is still unknown. Researchers know that armadillos can transmit the disease to humans, but the Florida Department of Health hasn't tested the strains in the nine patients to see whether they match those found in area armadillos, said Mara Burger, a spokesperson for the Florida Department of Health.
Every year, between two and 10 people in Florida are diagnosed with leprosy, also known as Hansen's disease, Burger said. This year's cases aren't clustered, and because "the incubation period [the time between exposure and the appearance of symptoms] for Hansen's disease is 2 to 10 years," it can be "difficult to identify the exposure source," Burger told Live Science in an email.
"The disease itself is challenging to diagnose, as many doctors have not come in contact with it before," she said.
Cases of leprosy are also seen in Texas, where between 10 and 25 people were diagnosed each year from 2010 to 2014, said Chris Van Deusen, a spokesperson for the Texas Department of State Health Services. (Texas doesn't have leprosy stats yet for 2015, Van Deusen said.) In Louisiana, health officials recorded eight leprosy diagnoses in 2011 and six a year from 2012 to 2014, said Ashley Lewis, a spokesperson for the Louisiana Department of Health and Hospitals. The state has eight cases reported so far this year, she added.
However, leprosy is relatively difficult to catch. It spreads by prolonged contact with an infected person or animal, and the bacteria are likely dispersed via sneezing or coughing, Schaffner said.
Leprosy primer The disease, which began infecting humans at least 4,000 years ago, is a chronic condition caused by the bacterium Mycobacterium leprae. It primarily affects the peripheral nerves, skin, upper respiratory tract, eyes and the soft inner lining of the nose, according to the National Institute of Allergy and Infectious Diseases.
People may experience some loss of feeling because the bacteria attack their nerves.
"The nerve can be a little bit swollen," Schaffner said. "If you biopsy the nerve, you can see the leprosy bacteria there."
This lack of sensation, as well as muscle weakness and paralysis, can lead to injuries, and sometimes, people get their fingers, toes and even nose amputated if the disease has progressed too far, Schaffner said.
People can also get leprosy as a blood disease. When that happens, the bacterium slowly infiltrates the tissues under the skin, and causes disfiguring bumps and pouching skin on the face. This can lead to lionlike facial features, in which infected people develop an exaggerated brow and strong cheekbone features, Schaffner said.
"That was part of what made leprosy so offensive or reprehensible to society," Schaffner said. "These people looked fierce and strange."
Many societies ostracized people with leprosy, but successful treatments began in the 1940s, and now the disease is treatable with long-term antibiotic use, Schaffner said. Moreover, approximately 95 percent of people appear to be resistant to infection, Burger added.
An estimated 2 million people around the world are permanently disfigured by leprosy, according to the Centers for Disease Control and Prevention. In the U.S., the National Hansen's Disease Program receives federal money to run 11 clinics in seven states and Puerto Rico that treat the disease, according to the CDC.
Original article on Live Science.
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Don't touch the armadillo!
In just 10 steps, a person can become infected with a virus originating in an animal that the individual may not even have had direct contact with, suggests a new study. While fruit bats are necessary pollinators, they could also harbor deadly viruses, according to the study, which is published in the latest issue of the Proceedings of the Royal Society B. "Viruses that originate in bats may be the most notorious emerging zoonoses that spill over from wildlife into domestic animals and humans," wrote lead author Raina Plowright of the Pennsylvania State University Center for Infectious Disease Dynamics and her team. Zoonoses are diseases that can jump from non-human animals to humans, and vice versa. Fruit bats may harbor Ebola, Hendra, Nipah and Marburg viruses, in addition to others. Plowright and other researchers continue to investigate why this is the case, but it appears that bats have superior immune systems that perhaps arose due to an indirect effect of evolutionary adaptions for sustained flight. "As a consequence," Plowright and her colleagues explained, "bats may be tolerant of infection and thus may be exceptionally hospitable reservoir hosts."
Although many viruses have been around for hundreds of years, zoonotic diseases are posing more health threats now. Some viruses mutate over time. Land use changes tied to human population growth are also critical to the spread of these viruses. In certain parts of Australia, for example, areas that were once relatively unpopulated are now being used to raise animals, like horses and cattle. The researchers explain that "when nectar flows are diminished due to seasonal conditions, habitat loss or climate change, bats seek alternative food sources in urban" and other populated regions. In some locations, the fruit bat population has increased fourfold since bats, with diminished natural resources, crowd into the remaining places where they can feed.
The researchers found that an increasing number of bats are skipping migrations and switching to "consistently available, but poorer quality" food sources, including "fruiting trees planted in horse paddocks. These resident bats become particularly susceptible to winter and spring food shortages." While a fruit bat may show no signs of being ill, it might still harbor a virus that could shed on partially eaten fruit via saliva.
As multiple bats feed on fruit in a tree, the virus could easily spread from bat to bat, such as when a bat eats off of a fruit that another virus-harboring bat fed on.
"Bats spend little time on the ground," Plowright and her team point out. This means that a virus is most likely to be transmitted from bats to other animals by particles they shed in their waste. This can occur when bats foraging or roosting in a tree defecate, and the urine and feces fall at the base of a tree.
Assuming bats are healthy and are free to forage without human intervention, having waste collect at the base of trees can actually be a perk to an ecosystem. Seeds in the waste are well fertilized. They land in shade provided by the tree that allows for greater moisture retention. With sunshine and over time, the seeds may sprout and lead to new healthy fruit trees that can support not only bats, but also other animals. This ideal scenario can turn into something more sinister when human land use changes, global warming, disease-carrying bats, and limited bat food sources are all factored in. These factors put horses, released into areas where bats feed, at greater risk.
In places where horses are raised, the horses may choose to feed at the base of trees, where grass is plentiful. In doing so, they can become exposed to certain viruses shed by the bats. This has proven to be especially common in the spread of Hendra virus, which has a 50 percent mortality rate in humans, according to the Australian Veterinary Association (AVA). An AVA fact sheet mentions that Hendra virus "is an emerging disease that was first identified in 1994." So far, it has only been found in Australia, but since it is a zoonotic disease, health officials continue to monitor it closely.
In addition to grazing on virus-contaminated plants, horses may contract a bat-harbored virus by drinking contaminated water, or even just by sniffing a contaminated surface, the study reports. Discarded fruit pulp that bats have fed upon is also thought to be a route of transmission. In Malaysia, the Nipah virus has spread to pigs via such discarded pulp. In Central Africa, apes are believed to have contracted Ebola after consuming contaminated fruit pulp. Once an animal, such as a horse, contracts a zoonosis, it likely lacks the protective immunity of bats and may become visibly ill. Horses, often kept in close contact within barns, pens and other structures, can then spread the virus to each other.
"Some horses may eliminate infection in the mucus membranes of the upper respiratory tract," while others may harbor the virus, but show no signs of infection. A person in close contact with a sick horse, either dead or alive, could then be at risk for the zoonosis. It should also be mentioned that humans could contract a zoonotic disease directly from its original animal source. Fruit bats are commonly eaten in certain parts of Africa, with health experts noting that some Ebola victims either ate bat meat or otherwise came into close contact with fruit bats.
Once a person contracts a zoonosis, it can then spread from person to person, as has been very evident with Ebola. At first it might seem like killing fruit bats would lessen risk. But this could prove disastrous. Not only would the ecosystem lose essential pollinators, throwing the food chain into a tailspin, but also "disrupting (bat) colonies may increase the amplitude of viral shedding events." As for humans, it's believed that stress facilitates virus shedding, so it's possible that the problem would only escalate. Instead, "conservation and restoration of critical bat feeding habitat should reduce the risk of nutritional stress and reduce urban colonization by bats," the scientists propose. They add that, in the virus spread scenario involving horses, healthy horses with ample food are at less risk for zoonosis. Finally, the researchers mention, "Vaccination is the standard intervention to modify host susceptibility." Developing vaccines to prevent all zoonotic diseases is essential to safeguarding humans as well as other animals. Fruit bats might even prove to be our saviors, since studies on their unique immune systems could lead to better treatments for many diseases.