The risk of rabies spread in Japan: a mathematical modelling assessment

Abstract

Rabies was eliminated from Japan in 1957. In the 60 years since elimination, vaccination coverage has declined and dog ownership habits have changed. The purpose of this study was to assess the current risk of rabies spread in Japan. A spatially explicit transmission model was developed at the 1 km2 grid scale for Hokkaido and Ibaraki Prefectures. Parameters associated with dog movement and bite injuries were estimated using historical records from Japan, and were used with previously published epidemiological parameters. The final epidemic size, efficacy of rabies contingency plans and the influence of dog owner responses to incursions were assessed by the model. Average outbreak sizes for dog rabies were 3.1 and 4.7 dogs in Hokkaido and Ibaraki Prefectures, respectively. Average number of bite injury cases were 4.4 and 6.7 persons in Hokkaido and Ibaraki Prefectures, respectively. Discontinuation of mandatory vaccination increased outbreak sizes in these prefectures. Sensitivity analyses showed that higher chance of unintentional release of rabid dogs by their owners (from 0.5 to 0.9 probability) increased outbreak size twofolds. Our model outputs suggested that at present, incursions of rabies into Japan are very unlikely to cause large outbreaks. Critically, the reaction of dog owners to their dogs developing rabies considerably impacts the course of outbreaks. Contingency measures should therefore include sensitisation of dog owners.

Evaluating the contact rate between companion dogs during dog walking and the practices towards potential cases of rabies among dog owners in Japan

“…From the current survey results, it can be deduced that the probability of a Japanese dog owner following the best practice mentioned above would be approximately 0.75 (based on the average score in Construct #1 which is 3 out of 4). According to the simulation model by Kadowaki et al (), if the probability of an owner releasing a rabid dog increased from 0.5 to 0.9 (corresponding to a decrease in the probability of best practice from 0.5 to 0.1), the number of rabies cases in an outbreak would increase 2.4‐fold from 4.7 to 11.3. In addition, it would be beneficial to conduct further research to assess the KAP of doctors and veterinarians in Japan towards rabies, thus identifying any gaps and areas of concern that should be addressed in future continuous professional training (Hennenfent, Iyengar, & Davies‐Cole, ).…”

“…In 2008, France experienced a rabies outbreak involving three pet dogs where the primary case was illegally introduced from Morocco by a dog owner and eventually led to two local secondary cases (Allibert et al, ). Thus, one can reasonably anticipate that a rabies incursion into Japan would follow the above scenario and the behaviour of local dog owners would play an important role in influencing how the disease might spread in the domestic dog population (Kadowaki, Hampson, Tojinbara, Yamada, & Makita, ).…”

A Comparative Review of Prevention of Rabies Incursion between Japan and Other Rabies-Free Countries or Regions

“…We also estimated the potential size of any outbreak of rabies among dogs, including owned dogs and strays, using two different prefectures as models in Japan. These results have been published elsewhere (12) and are summarized below.…”

“…We selected two prefectures, namely, Hokkaido and Ibaraki, as models with different demographics and environments. The mean outbreak size for Hokkaido was 22.8 dogs (95 CI: 1-142) in the absence of vaccination of pets, whereas that for Ibaraki was estimated to be 21.7 dogs (95 CI: 1-110) (12). With current vaccination coverage, the outbreak sizes were 3.1 dogs (95 CI: 1-14) and 4.7 dogs (95 CI: 1-37) for the respective prefectures.…”

Benefit-cost analysis of the policy of mandatory annual rabies vaccination of domestic dogs in rabies-free Japan

“…The number of human victims bitten or injured by a rabid dog was based on Kadowaki et al [6]. It was assumed that all victims suffer either a Category II or III exposure requiring PEP under WHO recommendations and all of them can receive timely complete PEP given the fact that Japan is a developed country with a very high human development index of 0.903 [15, 18, Human Development Report 2015 data].…”