Risk for Rabies Transmission from Encounters with Bats, Colorado, 1977-1996
1999

Risk of Rabies from Bat Encounters in Colorado

Sample size: 4470 publication Evidence: moderate

Author Information

Author(s): W. John Pape, Thomas D. Fitzsimmons, Richard E. Hoffman

Primary Institution: Colorado Department of Public Health and Environment

Hypothesis

What is the risk for rabies transmission to humans from encounters with bats?

Conclusion

Bats that interact with humans are more likely to have rabies, especially those that bite.

Supporting Evidence

  • Rabies was diagnosed in 685 (15%) of 4,470 bats tested.
  • The prevalence of rabies in bats that bit humans was 2.1 times higher than in bats that did not bite humans.
  • None of the persons bitten by bats got rabies.
  • At least a third of the encounters were preventable.

Takeaway

If you see a bat, be careful! Bats that bite people are more likely to have rabies, which can make you very sick.

Methodology

The study analyzed rabies prevalence in bats submitted for testing and characterized bat-human encounters over a 20-year period.

Potential Biases

The passive surveillance system may have missed unreported encounters and rabies cases.

Limitations

The study may not represent all bats that encounter humans, and not all encounters were documented.

Participant Demographics

Of the 240 persons who encountered bats, 59% were male and 41% were female, with ages ranging from 10 months to 81 years.

Statistical Information

Confidence Interval

95% confidence interval 1.7 to 2.5

Statistical Significance

p<0.001

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