Group of Peruvian Amazon people 'resistant to rabies'

[Shiloh]

Source: http://www.theaustralian.com.au/new...istant-to-rabies/story-e6frg6so-1226441240742

Amazon people 'resistant to rabies'

From: AFP
August 02, 2012 11:07AM

SCIENTISTS said that a rare group of people in the Peruvian Amazon appears to have some natural resistance to rabies, which is widely considered fatal if not immediately treated.

The research reported in the American Journal of Tropical Medicine and Hygiene is based on blood samples from six people who said they had never been vaccinated against rabies.

But the group showed "rabies virus-neutralizing antibodies," indicating for the first time that some people may develop an immune response that scientists could study in order to find new paths to treatment....

 

[Giuseppe]

Re: Group of Peruvian Amazon people 'resistant to rabies'

[Source: US Centers for Disease Control and Prevention, full page: (LINK).]

CDC: Amazon study finds routine rabies exposures

Some people living in two Amazon communities in Peru survived being exposed to rabies virus without receiving vaccination, according to researchers from the U.S. Centers for Disease Control and Prevention, in collaboration with the Peruvian Ministry of Health. While avoiding rabid animal exposures, and receiving injections administered after a person is exposed to rabies virus remain the best ways to protect against acquisition of this fatal disease, there is strong evidence that an immune response may occur in certain communities where people are regularly exposed to the virus, according to a study published today.

The study, ?Evidence of Rabies Virus Exposure among Humans in the Peruvian Amazon,? is in the August issue of the American Journal of Tropical Medicine and Hygiene. The researchers conducted a survey in two communities in a remote section of the Peruvian Amazon where outbreaks of human rabies infections caused by vampire bat bites have occurred regularly over the past two decades. Several of these people who were previously exposed to rabies virus survived without vaccination, although the study cannot determine whether they ever experienced clinical disease.

The study consisted of 92 people, 50 of whom reported previous bat bites. Blood samples were taken from 63 people, and 7 (11 percent) were found to have ?rabies virus neutralizing antibodies,? evidence that they had been previously exposed to the rabies virus. Although one person with antibodies reported receiving vaccine previously, the other people with antibodies are unlikely to have received medical care following prior 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 suggest vampire bats as the source of rabies virus exposure.

?Nearly all rabies virus exposures that proceed to clinical infections are fatal. Our results support the idea that under very unique circumstances there may be some type of enhanced immune response in certain populations regularly exposed to the virus, which could prevent onset of clinical illness,? said Amy Gilbert, PhD, of CDC?s National Center for Emerging and Zoonotic Infectious Diseases and lead author of the study. ?However, a series of injections following an exposure remains the best way to protect people against rabies.?

Although few studies have ever looked, the findings in this paper may not be unique among persons at high risk for rabies virus exposure, such as persons experiencing high levels of bat or carnivore contact in areas where rabies is endemic.

Rabies is a preventable viral disease most often transmitted through the bite of a rabid animal. In the United States, the vast majority of rabies cases reported to CDC each year occur in wild animals like raccoons, skunks, bats, and foxes. Rabies virus infects the central nervous system, ultimately causing disease in the brain and death. More than 55,000 people worldwide are estimated to die of rabies each year.

Early symptoms of rabies include fever, headache, and general weakness or discomfort. As the disease progresses, more specific symptoms appear and may include insomnia, anxiety, confusion, slight or partial paralysis, excitation, hallucinations, agitation, hypersalivation (increase in saliva), difficulty swallowing, and hydrophobia (fear of water). Death usually occurs within days of the onset of these symptoms.

In the United States, human deaths from rabies have declined over the past century from more than 100 annually to an average of two per year because of aggressive campaigns to vaccinate domestic animals against the disease. Recent human rabies cases are primarily due to bat bite exposures. Human and domestic animal contact with bats should be avoided. People who may have had contact with bats should seek medical advice, and such exposures should be promptly reported to local public health authorities.

For more information on rabies, visit CDC?s rabies Web site at http://www.cdc.gov/rabies/. For general information about this study, visit the ASTMH site at http://www.astmh.org/ .

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[mixin]

Re: Group of Peruvian Amazon people 'resistant to rabies'

Published Date: 2012-08-05 09:36:07
Subject: PRO/AH> Rabies - Peru, comment
Archive Number: 20120805.1228965
RABIES - PERU, COMMENT
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A ProMED-mail post
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Date: Fri 3 Aug 2012

From: Steven Van Gucht [edited]


I would like to comment on the posting about the apparent abortive rabies virus infections observed in Peru [ProMED-mail archive no. 20120802.1226037].

The occurrence of such abortive infections is indeed a very interesting observation. I would like to add that there are some older reports that describe the occurrence of seropositive individuals in some populations at risk, which seem to have seroconverted without the development of brain disease:

T.C. Doege, R.L. Northrop, Evidence for inapparent rabies infection, Lancet 2 (1974) 826-829.

D. Black, T.J. Wiktor, Survey of raccoon hunters for rabies antibody titers: pilot study, J Fla Med Assoc 73 (1986) 517-520.

Actually, very little is known about the behaviour of the rabies virus in peripheral tissues before entry in the central nervous system. In mice, we observed that infection of macrophages might enhance the antibody response to the rabies virus, results are described in a paper that we recently submitted for publication.
--

Communicated by:

Steven Van Gucht

Head of Scientific Service
Viral Diseases | Communicable and Infectious Diseases
Scientific Institute of Public Health
Rue Engelandstraat 642 | 1180 Brussels, Belgium

[ProMED thanks Steven Van Gucht for his comments and the references about rabies antibodies in unvaccinated people. The biological significance of antibodies in the individuals remains to be determined, but one hopes that reports such as these will stimulate further research.

http://www.promedmail.org/direct.php?id=20120805.1228965

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Link to the open access full text article:
http://www.ajtmh.org/content/87/2/206.full

Abstract:

Evidence of Rabies Virus Exposure among Humans in the Peruvian Amazon

Amy T. Gilbert*,?, Brett W. Petersen?, Sergio Recuenco, Michael Niezgoda, Jorge G?mez, V. Alberto Laguna-Torres and Charles Rupprecht

In May of 2010, two communities (Truenococha and Santa Marta) reported to be at risk of vampire bat depredation were surveyed in the Province Datem del Mara??n in the Loreto Department of Per?. Risk factors for bat exposure included age less than or equal to 25 years and owning animals that had been bitten by bats. Rabies virus neutralizing antibodies (rVNAs) were detected in 11% (7 of 63) of human sera tested. Rabies virus ribonucleoprotein (RNP) immunoglobulin G (IgG) antibodies were detected in the sera of three individuals, two of whom were also seropositive for rVNA. Rabies virus RNP IgM antibodies were detected in one respondent with no evidence of rVNA or RNP IgG antibodies. Because one respondent with positive rVNA results reported prior vaccination and 86% (six of seven) of rVNA-positive respondents reported being bitten by bats, these data suggest nonfatal exposure of persons to rabies virus, which is likely associated with vampire bat depredation.

+ Author Affiliations
National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; Direcci?n General de Epidemiolog?a, Ministerio de Salud, Lima, Per?; Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, Georgia; Virology Department, US Naval Medical Research Unit 6, Lima, Per?

+ Author Notes

Authors' addresses: Amy Gilbert, Brett Petersen, Sergio Recuenco, Michael Niezgoda, and Charles Rupprecht, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, E-mails: fcj6@cdc.gov, ige3@cdc.gov, fni9@cdc.gov, man6@cdc.gov, and cyr5@cdc.gov. Jorge G?mez, Direcci?n General de Epidemiolog?a, Ministerio de Salud, Lima, Per?, E-mail: jgomez@dge.gob.pe. V. Alberto Laguna-Torres, Virology Department, US Naval Medical Research Unit 6, Lima, Per?, E-mail: alberto.laguna@med.navy.mil.
↵*Address correspondence to Amy Gilbert, Centers for Disease Control and Prevention, 1600 Clifton Rd, NE, Mailstop G33, Atlanta, GA 30333. E-mail: fcj6@cdc.gov
↵?These authors contributed equally.