Read the Article in JPHMP
Rabies is fatal almost 100% of the time. When a person is exposed to a potentially rabid animal, we can test the animal to determine its rabies status: if it’s negative, we rule out rabies, and if it’s positive, the patient needs to receive rabies post-exposure prophylaxis (PEP), which is lifesaving but very expensive and time consuming. When a test is neither negative nor positive (ie, “unsuccessful”), however, we must assume that the animal was rabid and recommend PEP for the exposed person. Many unsuccessful tests occur when the animal specimen is desiccated, deteriorated, decomposed, or damaged—the “4 Ds.” Unsuccessful tests often lead to PEP that could have been avoided if the test was successful. In this study, we wanted to figure out which animal species and which submitters were most likely to be involved in unsuccessful test situations in Utah so we could take steps to decrease them.
In our new article in the Journal of Public Health Management & Practice, we analyzed the records of 2,806 tests performed for rabies at the Utah Public Health Laboratory during 2014–2023.
What we found
We found 113 unsuccessful tests (4% of submissions). Among these, bats, raccoons, skunks, dogs, and cats were the most common animal types. Here’s the breakdown of the percentage of unsuccessful tests per number submitted for those animal types:
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- Skunks: 10.3 (6 of 58)
- Raccoons: 6.9% (17 of 246)
- Bats: 5.6% (64 of 1,144)
- Cats: 2.0% (12 of 598)
- Dogs: 1.1% (7 of 631)
Frequent submitters were animal control entities (AC), local health departments (LHD), the Utah Veterinary Diagnostic Laboratory (UVDL), veterinarians, the Utah Division of Wildlife Resources (DWR), and citizens. Here’s the breakdown of the percentage of unsuccessful tests per number submitted by submitter type:
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- Citizens: 10.8% (16 of 148)
- LHD: 4.7% (28 of 595)
- DWR: 3.7% (6 of 163)
- UVDL: 3.5% (10 of 286)
- AC: 3.2% (42 of 1,320)
- Veterinarians: 3.2% (8 of 249)
Citizens had the highest unsuccessful test rate—statistically higher than any other submitter type. Within the AC and LHD submitter types, performance varied widely by individual submitting entity; unsuccessful test rate ranges were 0.9–14% (AC) and 2–17% (LHD).
We performed several statistical tests to try to determine which factors helped explain what we observed. In particular, we were curious to know whether animal type or submitter type explained our results. Here’s what we found consistently in statistical analysis:
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- Bats, raccoons, and skunks (when compared with other animal types) had statistically higher unsuccessful test rates across submitter types, suggesting that these animal types may be more prone to unsuccessful submission.
- Citizens (when compared with other submitter types) had statistically higher unsuccessful test rates across animal types, suggesting that citizens are not an ideal choice for submission.
Recommendations
Based on these findings, we recommend the following:
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- Conduct focus groups with most successful submitters to identify model practices and share them with other submitters.
- Train submitters on proper screening and submission of animal specimens, especially of wildlife.
- Encourage submission through the most successful submitter types, including animal control entities and local health departments; in particular, citizens should not submit directly, but should submit through trained submitters.
To our knowledge, this is the first report of this type of analysis. Other jurisdictions may consider similar analyses to help decrease unsuccessful submission of animal specimens for rabies testing. Strengthening collaboration between all rabies response partners can help facilitate more successful testing, which can lead to fewer administrations of avoidable, costly PEP and better public health outcomes.
Acknowledgements
We gratefully acknowledge all the manuscript co-authors: Clarissa Keisling, Will Boyd, Hannah Rettler, Heather Oltjen, Kacy Nowak, Kaona Ayres, Kim Kinnick-Hansen, Jesse Harbour, and Willy Lanier
We also would like to give a shout out to the many partners in Utah’s rabies surveillance, response, and prevention system who help keep rabies at bay!
