Dogs on the move: Estimating the risk of rabies in imported dogs in the United States, 2015-2022

Abstract

Background: Dog-mediated rabies virus variant (DMRVV), a zoonotic pathogen that causes a deadly disease in animals and humans, is present in more than 100 countries worldwide but has been eliminated from the United States since 2007. In the United States, the U.S. Centers for Disease Control and Prevention has recorded four instances of rabies in dogs imported from DMRVV-enzootic countries since 2015. However, it remains uncertain whether the incidence of DMRVV among imported dogs from these countries significantly surpasses that of domestically acquired variants among domestic U.S. dogs.

Aim: This evaluation aimed to estimate the number of dogs imported from DMRVV-enzootic countries and compare the risk of rabies between imported dogs and the U.S. domestic dog population.

Materials and methods: Data from the CDC's dog import permit system (implemented during 2021 under a temporary suspension of dog importation from DMRVV-enzootic countries) and U.S. Customs and Border Protection's Automated Commercial Environment system, each of which records a segment of dogs entering the U.S. from DMRVV-enzootic countries, was analysed. Additionally, we estimated the incidence rate of rabies in dogs imported from DMRVV-enzootic countries and compared it to the incidence rate within the general U.S. dog population, due to domestically acquired rabies variants, over the eight-year period (2015-2022).

Results: An estimated 72,589 (range, 62,660-86,258) dogs were imported into the United States annually between 2015 and 2022 from DMRVV-enzootic countries. The estimated incidence rate of rabies was 16 times higher (range, 13.2-19.4) in dogs imported from DMRVV-enzootic countries than that estimated for domestically acquired rabies in the general U.S. dog population.

Conclusions: Preventing human exposure to dogs with DMRVV is a public health priority. The higher risk of rabies in dogs imported from DMRVV-enzootic countries supports the need for importation requirements aimed at preventing the reintroduction of DMRVV into the United States.

Keywords: dogs; public health; rabies incidence; rabies virus; zoonoses.

FIGURE 1

Diagram of data availability for the number of dogs imported from DMRVV-enzootic countries via CBP’s Automated Commercial Environment system and CDC’s dog import permit system, 2022. The CBP’s Automated Commercial Environment system records the number of dogs imported via cargo from DMRVV-enzootic countries but does not include information on rabies vaccination certificates. While all dogs imported from DMRVV-enzootic countries with foreign-issued rabies vaccination certificates were required to be registered in the CDC’s dog import permit system during 2022, the transport method was an optional component to report. Thus, some dogs in the missing category (i.e., dogs in the orange dotted circle) from the CDC’s dog import permit system may have been imported via cargo, and their information may be included in CBP’s Automated Commercial Environment system. The CDC’s dog import permit system was implemented on August 1, 2021, and we only report data from the calendar year 2022. Data from CBP’s Automated Commercial Environment system is available for multiple years, and we focused on the period from 2015 through 2022. For the period from 2015 through 2022, we assumed the fraction of dogs imported as cargo each year would be similar to the estimated fraction of foreign-vaccinated dogs from DMRVV-enzootic countries imported as cargo during 2022. CBP, U.S. Customs and Border Protection; CDC, Centers for Disease Control and Prevention; DMRVV, Dog-mediated rabies virus variant.