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Husein et al. One Health Implement Res 2023;3:16-29 https://dx.doi.org/10.20517/ohir.2022.32 Page 26

bait not accepted was retrieved by the vaccinators. Furthermore, all discarded sachets were also collected,
thus reducing potential human contact with the bait considerably [41-42] . Another bait distribution system
proposed is handing out baits to dog owners at temporary bait delivery sites. During a field study, it was
shown that this method resulted in a high number of unintentional contacts with the baits; 1.7% of all
inhabitants claimed to have had contact with the baits during a subsequent survey, including a child putting
[43]
the bait in its mouth . In another study, baits were placed along transects to be located by dogs themselves,
similar to the approach used for wildlife. Here, 1.4% of the inhabitants claimed to have had contact with
[44]
vaccine baits, whereby most contacts involved children . These contacts do not necessarily lead to true
exposure to the vaccine virus. With the hand-out and retrieve system, this kind of direct contact with the
vaccine bait is almost completely excluded, although sometimes the owners offer the baits to the dogs.
However, indirect human contact with the vaccine virus cannot be excluded as there is a possibility that a
dog orally vaccinated will bite or lick someone in the hours following bait consumption. Depending on the
vaccine construct used, the viable virus will sometimes remain present in the oral cavity for several hours
after bait consumption, and thus the dog can transmit the virus during this period . However, as oral
[45]
vaccination is targeted at dogs that cannot be restrained and handled without special effort, these animals
cannot be marked and are thus not identifiable post-vaccination. Hence, it is difficult to determine the risk
of potential human exposure to the vaccine as a result of contact with orally vaccinated dogs. The sachets
used in this study contained a blue dye that visibly stained the oral cavity for a period similar to the
persistence of viable vaccine virus in the oral cavity after oral vaccination . Hence, during the bait
[36]
acceptance study and the follow-up survey, it could be estimated that 6.1% of the households providing bait
to dogs had direct contact with the dog, as the dye also stains clothes and human skin. All 23 contacts
reported were considered Type I according to the WHO categorization for contacts with rabies virus, i.e.
touching an animal or licking on intact skin, which is not considered rabies exposures . This underscores
[46]
the low risk of human exposure to the vaccine-dosed virus using this distribution system. It must be stated
here that when using oral rabies vaccines meeting the safety requirements as recommended by WHO and
WOAH [39,45] , the probability that “true” exposures to the vaccine bait would lead to serious adverse events is
rd
negligible, as shown for the 3 generation oral rabies vaccine, SPBN GASGAS, a candidate for further ORV
studies in Bali .
[41]
CONCLUSIONS
A locally-made intestine bait and an industrially manufactured egg-flavored bait were readily taken up by
local dogs in Bali. This ready acceptance of trial baits offers a unique opportunity to deliver effective ORV to
dogs that cannot be easily caught and restrained for parenteral vaccination. Most field workers consider
ORV to be better suited than CVR for vaccinating these free-roaming dogs. The human risk assessment
indicated that in Bali, there is a risk, albeit small, that people can come in contact with the vaccine through
direct contact with dogs previously offered a bait. Hence, only vaccines with a high safety profile should be
used.

RECOMMENDATION
ORV should replace the presently used method of CVR for free-roaming dogs as a complementary tool to
increase vaccination coverage and thus to effectively interrupt rabies transmission among dogs. This will
support the elimination of dog-mediated rabies from Bali, and potentially from other areas of Indonesia.

DECLARATIONS
Acknowledgments
Special thanks to Steffen Ortmann (CEVA SA), who prepared the manufacturer’s fishmeal and egg-flavored
baits. Appreciation for Denni Rajagukguk and Ni Wayan Wardani (AIHSP), who assisted in the preparation