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Practicality of rabies postexposure prophylaxis guidelines questioned
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Current recommendations to vaccinate individuals who were possibly exposed to a bat without direct physical evidence are too costly to justify, according to findings from a new study by Canadian researchers.
Bedroom bat exposure without recognized physical contact accounted for one case of human rabies per 2.7 billion person-years in Canada and the United States, data from the risk analysis study indicated. Based on these estimates, the researchers projected that it would be necessary to vaccinate 314,000 to 2.7 million people to prevent a single case of human rabies acquired in this manner.
With the complete course of vaccines and immunoglobulins required for full rabies postexposure prophylaxis (RPEP) estimated at c$1,000, it would cost about c$2 billion annually to provide the biological products and virological analyses necessary to comply with current recommendations, according to the researchers.
Additionally, the numbers of full-time health care personnel needed to investigate rabies exposure and to administer RPEP would range from 293 to 2,500.
“The associated resources required to prevent a single case of human rabies through RPEP for bedroom exposure appears to be overwhelming,” and would “exceed what even the most conscientious physician could consider to be reasonable,” the researchers wrote.
Furthermore, data indicated that less than 5% of participants who were eligible for treatment actually received postexposure prophylaxis as recommended.
The researchers projected that 20- to 30-fold greater resources would be needed to reach full compliance with current recommendations. “A recommendation that is known to be sustainable only if ignored by most eligible people is of doubtful usefulness and questionable ethics,” they wrote. – by Nicole Blazek
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Clearly decisions to administer RPEP are complex, not cavalier, and such suggestions are not new to many of us who grapple with these issues on a daily basis and have done so for quite some time (and not lightly, especially after conversations with individuals who have lost family members to rabies.)
Current recommendations are based in part upon U.S. public health data, current biology and common sense.
Obviously the epidemiology of bat rabies between the United States and Canada are quite different. For example, exposure to bats is much longer, due to a pronounced frost-free season, in the southern latitudes; bat species biodiversity and abundance are exceptionally decreased up north, where few people live by comparison with most of the United States.
The current recommendations do not state to administer RPEP with a bat in a room with a person, but rather are formed on the basis of a probabilistic algorithm of outcomes related to the opportunity of perception of a stimulus and the ability to detect a lesion when an animal is present. In the vast majority of cases, when in reasonable doubt, testing the suspect animal will result in a negative outcome (about greater than 95% of the time).
Moreover, after the fact, I am sure that once a rabid bat is found in the bedroom with a crying baby, the last thing that most concerned parents will wish to discuss is the wisdom or ethics of an opinion generated solely in an economic analysis!
– Charles E. Rupprecht, VMD, PhD
Chief of the CDC’s Rabies Program
This paper contains some assumptions that will make it very difficult to use it to change public health practices regarding the recommendations for and use of RPEP following potential exposure to bat rabies. The biggest problem is the calculation of the denominator of those seeking RPEP following potential exposure to a bat.
In effect, the authors have assumed that anybody who has been “in the presence of a bat” will turn up at a physician’s office or emergency room and ask to be given RPEP, hence their very high estimate of numbers-needed-to-treat.
Whilst it is true that there have been increases in numbers of RPEP related to bat exposures, such increases have never been on the magnitude of those calculated by DeSerres et al.
What would have been useful to read in the paper is a set of sensitivity analyses examining the impact of different percentages of persons who were in the presence of a bat who actually requested RPEP.
In a paper we published last year we estimated that the cost effectiveness of RPEP following “possible bat bite exposure” is $2.9 million per life saved.
– Martin I. Meltzer, MS, PhD
Senior Health Economist and Distinguished Consultant at the CDC
*DISCLAIMER: The opinions expressed in these perspectives are those of the individuals and do not necessarily represent the official views and policies of the U.S. Centers for Disease Control and Prevention (CDC).