September 15, 2012

 

 Villagers had rabies antibodies without vaccination


  A vampire bat captured in Peru
  Courtesy of Dr. Daniel Streicker

  A village in Santa Marta, Peru
  Courtesy of Dr. Amy Gilbert
 
Posted on September 5, 2012
 
Some villagers in Peru have survived exposure to rabies virus and developed antibodies without vaccination, a recently published article states.

Researchers with the Centers for Disease Control and Prevention found rabies virus neutralizing antibodies in six unvaccinated people and one previously vaccinated person after taking sera from 63 residents of the Amazonian villages of Truenocha and Santa Marta, according to an article published in the August 2012 issue of the American Journal of Tropical Medicine and Hygiene.

A CDC announcement indicates the six who had antibodies but no known history of vaccination were unlikely to have received medical care following previous bat bites.

“It could not be determined when the virus exposures occurred or which animals were responsible, but the history of repeated bat bites reported among persons in this area strongly suggests vampire bats as the source of rabies virus exposure,” the announcement states.

The report is available at www.ajtmh.org/content/87/2/206.full.

Using an indirect fluorescent antibody assay, the researchers also found rabies virus binding antibodies in four of the 63 people from whom samples were taken, two of whom also had virus neutralizing antibodies. Including the five others who had virus neutralizing antibodies, all nine individuals seropositive for anti-rabies antibodies said they had been ex-posed to bats, the report states.

Amy Gilbert, PhD, lead author for the report, said in the CDC announcement that the study results support the idea that some populations regularly exposed to rabies virus could have an enhanced immune response that would prevent clinical illness.

In the same issue of the journal, Rodney E. Willoughby, MD, said in an editorial that the CDC officials’ article “challenges the orthodoxy that rabies is untreatable and universally fatal.” Dr. Willoughby led the team that improvised the Milwaukee Protocol first used to save a 15-year-old girl infected with rabies in 2004, and he supports medical teams using the protocol to treat patients with rabies. He works as a professor of pediatrics at Medical College of Wisconsin and is a staff member at Children’s Hospital of Wisconsin.

“Careful, respectful genetic study of these genetically unique populations may provide information on which pathways in human biochemistry and physiology promote resistance to human rabies,” Dr. Willoughby wrote.

“Equally important, knowing that there is a continuum of disease, even for infectious diseases like rabies, should push us harder to try for cures when confronted by so-called untreatable infectious diseases or intoxications.”

Dr. Willoughby’s article is available at www.ajtmh.org/content/87/2/205.full.