A Qualitative Risk Assessment of Rabies Reintroduction Into the Rabies Low-Risk Zone of Bhutan

Abstract

In Bhutan, dog-mediated rabies has been successfully eliminated from most regions of the country but remains endemic in the Southern region and sporadic incursions are also reported in the East. Elimination of rabies from the southern part of Bhutan is challenged by the porous border with the neighboring states of India which facilitates free and unregulated movement of animals. Around 17 outbreaks of rabies are reported annually in dogs and other domestic animals, posing continuous public health risks and economic losses. Furthermore, due to anthropogenic factors, such as increasing human settlements along highways, increased animal transportation, and the complex and changing human-pet relationship, there is potential to reintroduce rabies from rabies highrisk zone to rabies low-risk zone. This study was undertaken to estimate the risk of rabies re-introduction to the rabies low-risk zone by performing a qualitative risk assessment. The assessment was conducted for three risk pathways (stray dog-pathway, pet dogpathway and cattle-pathway) under two scenarios: (1) no risk mitigation measures in place and (2) current risk mitigation measures in place. The current control measures include Government led programs, such as mass dog vaccination and dog population management, regulation of the movment of animals through pre-travel checkup and health certification, regular awareness education and rabies surveillance in the rabies endemic areas. The probability of an event occurring was assigned using the data from the available literature. Where gaps in knowledge existed, expert opinion, elicited through modified Delphi method, was used. Under the scenario in which no risk mitigation measures were in place, the risk of rabies re-introduction was estimated to be medium for the stray-dog pathway with a low level of uncertainty, low for pet-dog pathway with a low level of uncertainty, and very low for the cattle-pathway with a medium level of uncertainty. When current risk-mitigation measures were included, the risk of rabies reintroduction was estimated to be very low for the stray-dog pathway with a medium level of uncertainty, low for the pet dog-pathway with a low level of uncertainty, and extremely low for the cattle-pathway with a medium level of uncertainty. The risk of rabies re-introduction through all the pathways was greater than negligible. These findings highlight the importance of maintaining and enhancing current risk mitigation measures to prevent re-introduction of rabies into rabies low-risk zone.

A review of qualitative risk assessment in animal health: Suggestions for best practice

“…Published matrices using a multiplicative risk framework varied in the RAs reviewed here. One of the most commonly used adheres to the principle that the product of two probabilities is always equal to the lowest probability ( Table 3 ) ( 6 , 9 , 30 , 40 , 42 , 46 ). This matrix defines a likelihood estimate for any binary combination of conditional events but does not allow for the product of multiple conditional probabilities to be lower than the lowest value of the individual probabilities.…”

“…The use of expert opinion was described by some authors to reduce the uncertainty surrounding parameters where data were scarce ( 7 , 30 , 39 , 41 , 42 , 52 ). Some studies used workshops involving experts from a range of relevant backgrounds to confirm risk parameters, risk pathways and numerical weightings for risk factors reaching a final consensus of agreement ( 7 , 52 ).…”

“…Some studies used workshops involving experts from a range of relevant backgrounds to confirm risk parameters, risk pathways and numerical weightings for risk factors reaching a final consensus of agreement ( 7 , 52 ). Additional studies employed the Delphi technique ( 39 , 42 ) to reach consensus. One study used the level of disagreement between different experts as an indicator of the level of uncertainty ( 39 ).…”

Impact of COVID-19 pandemic on the burden of dog bite cases at the National Referral Hospital in Bhutan

“…In the year 2019 and 2020 Bhutan reported total of 7083 and 6430 dog bites respectively 6,7 . Though rabies has been eliminated from the northern and central parts of Bhutan, there are risks of importing it from the south and eastern parts, as country shares border with India where several canine rabies outbreaks were reported in the past 8 . Thirteen human deaths were reported due to rabies following dog bites from 2009 to 2017 9 .…”