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Published Date: 2012-09-12 23:45:01
Subject: PRO/AH/EDR> Rabies - USA (19): (CA) bat
Archive Number: 20120912.1291986

RABIES - USA (19): (CALIFORNIA), BAT
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Date: Mon 10 Sep 2012
Source: L.A. Times [edited]
http://latimesblogs.latimes.com/lanow/2012/09/record-number-rabid-bats.html

45 rabid bats have been discovered in Los Angeles County so far this year [2012], the highest number in modern history, authorities said Monday [10 Sep 2012].

The previous high for a single year was 38 in 2011, and it is unclear what factors led to the increase.

13 of the rabid bats were found in the Santa Clarita area, according to a map of all the cases compiled by the Los Angeles County Department of Public Health. There are usually only 10 positive rabid bat reports a year.

Authorities warned the public to avoid handling bats and to report any found in homes or other places frequented by people to local animal control, especially if the animals are seen during the day.

Healthy bats tend to stay away from humans and are most active at night, authorities said.

[Byline: Jason Song]

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[It would be interesting to know whether the surveillance effort carried out during the last years was similar in order to assess whether the apparent rise in the number of rabid bats is real. A recent study (Vector-borne & Zoon Dis 12: 666-673) examined trends in bat rabies surveillance data in the USA and showed that bats submitted for diagnosis that originated in the southwest had increased odds of being rabid.

It would also be very useful to know what the bat population trends have been for the last few years in the southwestern USA.

Genetic evidence suggests that rabies is an old disease for bats in the New World. Bats from most of the estimated 41 bat species in the United States, when sampled in sufficient numbers, have been found to be infected with rabies virus. Rabies viruses recovered from bats were shown to be distinct from rabies viruses recovered from terrestrial mammals, suggesting that these viruses evolved within their bat hosts. Bat rabies viruses are genetically diverse, exhibiting mutations characteristic to each host bat species. These data suggest that rabies viruses are maintained in animal populations predominantly through intra-specific transmission. That is, transmission rarely occurs between species, such as when a rabid bat infects a human. These "spillover events" generally are not perpetuated in the recipient species.

A HealthMap of the affected area can be accessed at http://healthmap.org/r/27gI.

Portions of this comment were extracted from http://cid.oxfordjournals.org/content/35/6/738.short. - Mod.PMB]

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