"In people who are not vaccinated against measles due to health issues -- like severe immune-compromised people, for example, cancer patients -- this drug could provide protection in case they were exposed to measles," said lead researcher Richard Plemper, a professor at Georgia State University's Institute for Biomedical Sciences, in Atlanta.
Plemper said the drug could also be used in children whose parents object to vaccination. "If there is a measles outbreak, then this drug provides a new opportunity to control this outbreak and protect unvaccinated people," he said.
When the pill was tested on ferrets infected with a virus similar to measles, it kept the virus from growing and killing the animals, the researchers found. The virus tested was more dangerous than the measles virus.
Measles is not a benign disease, Plemper said. Even after the illness is over, children have a suppressed immune response that can last for several months, leaving them at risk for bacterial infections, he said.
"This drug is not an alternative to vaccination, rather it gives us an additional weapon against the virus," Plemper said. "We think that combined with vaccination, a drug that can rapidly silence an outbreak can help us eradicate this disease."
The new pill is known as ERDRP-0519. In the first animal trials, Plemper said, when it was given to ferrets "with a measles-like disease, which normally kills these animals within 20 to 40 days, they did not develop any symptoms. They all survived."
The researchers infected the ferrets again with another dose of the deadly virus, but because the animals had been treated with the drug before, they were immune, Plemper said.
He said the researchers used ferrets because they had to test the drug in animals before testing it in humans, but animals don't get measles.
"Therefore, we used a virus close to measles -- canine distemper virus -- which infects ferrets and has the same symptoms as measles in humans," Plemper said. "The only difference is that canine distemper virus is much more lethal. Untreated animals always die from the disease."
The study disclosed that three authors, including Plemper, are inventors on a patent for ERDRP-0519.
While the study results appear promising, scientists noted that research with animals often fails to provide similar results in humans.
The report was published April 16 in the journal Science Translational Medicine.
Measles, which spreads through the air by breathing, sneezing or coughing, is extremely infectious in children who are not immune, according to the U.S. Centers for Disease Control and Prevention. After infection, it takes about two weeks for symptoms such as skin rash, runny nose and fever to appear.
Although there has been progress in controlling measles around the world, some 150,000 people die from it each year -- a rate that has remained constant since 2007, the researchers noted.
Moreover, measles is making a renewed appearance in Europe, where it had previously been controlled. This resurgence has been attributed, in part, to reluctance of parents to have their children vaccinated and to the highly contagious nature of measles.
Measles may be rising in the United States as well. While about 60 people are usually reported to have measles annually, 189 cases were reported last year, according to the U.S. Centers for Disease Control and Prevention.
Dr. Marcelo Laufer, an infectious diseases specialist at Miami Children's Hospital, said that with measles vaccine, the condition is preventable, but there isn't enough vaccine coverage to eradicate it.
Laufer added that for this new drug to be effective, it has to be used as soon as measles is diagnosed. That might not be a simple task, since most doctors in the United States don't see measles cases, he said.
"If you show one of my residents somebody with measles, most probably the patient is not going to be diagnosed correctly," Laufer said. "So there needs to be a test to help us diagnose measles."
Meanwhile, the new pill has a long way to go before it can be used to treat human patients, if ever.
The pill, study author Plemper said, won't be ready for years, because it must first go through safety and effectiveness testing in people.
As with many antiviral drugs, the virus can become resistant. But Plemper's team found the strains of the virus that became resistant were in most cases milder.
Moreover, the ability of the drug-resistant virus to go from animal to animal was greatly reduced, compared to the original canine distemper virus. These findings are reassuring in that it is doubtful that a drug-resistant type of measles could become widespread, the researchers say.
To learn more about measles, visit the U.S. Centers for Disease Control and Prevention.