Rabies on the move in Indonesia – incursion into Bali and response

Putra, AAG (1), Gunata, I (2), Dharma, D (1), Scott-Orr, H (3) (1) Disease Investigation Centre, Denpasar, Bali, Indonesia (2) Livestock Service Badung District, Bali, Indonesia (2) NSW Department of Primary Industries, Orange, Australia

Abstract: Canine rabies was confirmed in Bali in late November 2008, following several months of reported outbreaks of unusual dog biting episodes and several human deaths with clinical signs of rabies. Bali had been historically free of rabies although the disease is endemic in other parts of Indonesia. Local veterinary authorities had a pre-prepared high level national disease control strategy for a rabies incursion into an uninfected island but many practical requirements for rapid response to the outbreak were unavailable and had to be assembled at short notice. These included laboratory diagnostic capacity, vaccination of people engaged in dog vaccination and elimination activities, an effective local control centre structure integrating human and veterinary surveillance and control activities, a public awareness program to gain community involvement, and an information management system allowing epidemiological assessment of progress.

Despite limited initial resources, there was a speedy response to the outbreak, with about 42,000 dogs vaccinated and 2,000 strays eliminated in the target area near confirmed outbreaks by May 2009. However, Bali has 3.5 million people, an estimated 700,000 dogs and 45 sacred monkey colonies, so a well resourced program underpinned by sound epidemiology will be needed to eradicate the disease from the island. An integrated strategy of surveillance, vaccination and elimination supported by a broad public awareness program, emergency management principles and epidemiological assessment has been developed and will be fine-tuned in the coming months in the light of surveillance of both the human and animal populations, subject to available funding.

Keywords: Rabies eradication, dog population dynamics and control, Indonesia, Bali.

Introduction: Bali is an Indonesian island, 140 by 80 km, with a human population of 3.5 million, mainly of Hindu religion, a roughly estimated dog population of 700,000, and about 45 sacred colonies of monkeys. Most of the local dogs are unrestrained and are semi scavengers and semi wild, while loosely regarded as being owned by different families. Many expatriates and wealthy Indonesians living in Bali have pet dogs which are better controlled. As a prime tourist destination, Bali is a market for goods and food from all over Indonesia, and there is very high movement of people, some with dogs, in and out of the island. Historically, rabies was present in Indonesia in the large islands of Java, Sumatra, Sulawesi and Kalimantan, but many smaller islands including Bali were free. However, rabies has been on the move eastwards and southwards in Indonesia, entering Flores island in 1997, Maluku province in 2003, and North Maluku province in 2004. In Bali, rabies was confirmed in human and dog cases on 23 and 28 November 2008 respectively, triggering a major response from Indonesian government services.

Spread and possible entry of rabies into Bali: The initial cases were detected in people on the southern Bukit peninsula of Bali, and rapid investigation revealed a history of outbreaks of unusual dog biting in several villages on this peninsula, back to June 2008. All human cases found so far were detected (most identified by clinical signs and history) on the Bukit peninsula as shown in Table 1. The earliest reported dog bite of a human rabies case was on 10.6.08, indicating a likely rabies entry time into Bali of early 2008.

The Bukit peninsula is a rocky, hilly outcrop connected to the rest of Bali by a narrow low lying isthmus of land, which is almost bisected by Bali’s international airport, although a main road traverses it. The peninsula has tourist complexes around the shore, a major university campus, and many villages in the centre recently built for workers from other parts of Indonesia, especially the Eastern Islands. Unggasan, where the first rabies cases occurred, is one such village. Bali’s major southern port, Benoa harbour, is on the eastern side of the isthmus south of the airport, while on the west is Jimbaran beach, a tourist area famed for its seafood restaurants, and served by a busy seaside market where fish catches from all over Indonesia are unloaded daily. It is likely that an infected dog from either Sulawesi or Flores entered either by fishing boat or cargo ship at Jimbaran or Benoa and that local spread on the Bukit peninsula occurred from June onwards, with some spillovers north of the airport by movements of pet dogs with their owners and possibly some straying of rabies affected dogs. Preliminary phylogenetic analysis of the virus supports this.

An intensive program of rabies post-exposure prophylaxis (PEP) of people bitten by dogs in Bali was instituted from early December 2008 which, with a large public awareness program, has so far prevented further human deaths but may be masking further spread of the virus in dogs. By mid May 2009, 4,853 people had reported dog bites and 4,609 had been given a full course of PEP.

Table1: Suspect or confirmed human rabies cases in Bali to March 2009 Location Dog bite Human death Days bite Dog status Dog survival (days Diagnosis date date to death after biting) Unggasan 19.10.08 21.11.08 33 Killed 19.10.08 0 Suspect rabies Unggasan 16.09.08 23.11.08 38 Dead 23.09.08 7 Laboratory Bit other dogs confirmed rabies Jimbaran 10.7.08 12.10.08 93 Bit 4 people ? Suspect rabies Disappeared Unggasan ..8.08 29.1.09 151 Disappeared ? Suspect rabies Unggasan 10.6.08 16.1.09 220 Disappeared ? Suspect rabies Unggasan ..10.08 27.1.09 88 Disappeared ? Lab. confirmed Pecatu 27.11.08 23.03.09 116 Disappeared ? Suspect rabies Unggasan ..10.08 26.03.09 146 Disappeared ? Suspect rabies

Up to early June 2009, 21 dogs were confirmed positive for rabies by direct immunofluorescence testing of brain tissue. 17 of these cases also occurred on the Bukit peninsula, but worryingly 5 cases were to the north in the main part of Bali. These cases were largely detected by investigation of dogs which bit people or shown other clinical signs of rabies, although 3 of the 21 were in stray dogs which were eliminated in May as part of control efforts in infected villages. However, overall surveillance of dog brains was very low up to this time, due to limited resources.

Table 2: Laboratory confirmed rabies cases in dogs in Bali to early June 2009 Month Nov Dec Jan Feb Mar Apr May Jun Dogs confirmed 1 9 2 - 2 1 5 1 rabies positive

Response: Indonesian veterinary and health authorities had a pre-prepared high level national disease control strategy for a rabies incursion into an uninfected island but many practical requirements for rapid response to the outbreak were unavailable and had to be assembled at short notice. These included laboratory diagnostic capacity, vaccination of people engaged in dog vaccination and elimination activities, an effective local control centre structure integrating human and veterinary surveillance and control activities, a public awareness program to gain community involvement, and an information management system allowing epidemiological assessment of progress. Above all, there were no pre-existing arrangements for rapid local program development, decision making and cost-sharing. The initial diagnosis was near the end of Indonesia’s financial year in December, making access to local funds more difficult. Despite this, there was an immediate response by Indonesia’s central, provincial and local district governments, through their veterinary, health and quarantine services, with extra Indonesian funding by January 2009 to the equivalent of AUD$400,000, as well as $100,000 emergency support from Australia, through an ACIAR project (“Improving veterinary service delivery in a decentralised Indonesia”).

The overall strategy adopted (following WHO guidelines) was of mass vaccination of dogs (and pet cats and monkeys) in villages and districts within 10km of a confirmed infected case, as well as selective elimination of stray dogs unwanted by the local community. Mass vaccination drives were held at weekends, to maximise the number of dog owners who would be at home, and were preceded by intensive public awareness activity including district and village meetings, TV, radio and print media campaigns and banner signage. This initial intensive program ran for over two months from late December 2008, with local official manpower augmented by volunteer veterinarians and veterinary students from Bali and Java. Coordination and information compilation and analysis was managed through an Incident Control System structure at the regional veterinary laboratory (Disease Investigation Centre) Denpasar and district veterinary services.

By May 2009, about 42,000 dogs had received a primary vaccination, and about 2,000 had received a booster dose (a 3-month booster is required for the locally produced inactivated canine rabies vaccine to provide a subsequent 12 months’ immunity). A further 2,000 stray dogs had been eliminated. However, this massive effort only achieved an approximate 40% vaccination coverage of the estimated total dog population in the target area. This is well below the minimum 70% needed to break the rabies virus transmission cycle. Since the mass vaccination campaign, there has been a birth pulse in the Bali dog population, which has a seasonal peak in March, further increasing the proportion of susceptible animals in the population. Two of the 21 confirmed positive dogs were 3 month old puppies, both detected in May 2009.

Discussion: A detailed study in six infected villages on the Bukit peninsula shows that the December to February mass vaccination program reduced but did not stop the rabies attack rate in these areas, meaning that there was still an ongoing risk of escapes from the area (Figure 1). With a rabies attack rate of 0.87% in March 2009, the risk of rabies infection (MacDiarmid and Corrin, 1999) was 0.87 x 60 days / 365 = 0.14 or 14 per 100 dogs or 1 of 10 dogs that move or relocate outside of the infected sub-district. Considering the mean observed incubation period of rabies in dogs in this outbreak of 1-2 months, the risk of new infections in May and June 2009 can be assessed. This correlates with the increase in rabies positive dogs detected in May.

Figure 1: Rabies Attack Rate (%) on Dogs in 6 infected villages in Bukit peninsula, Bali

2.5 Estimated Dog Population, May = 8,512 2 (Dog : Human Ratio = 1 : 8.27

1.5 First case: in human (23 Nov) and dog (28 Nov) 1 Human bitten by dog on 16-09-2008

0.5

0 May Jun Jul Aug Sep Okt Nov Dec Jan Feb Mar

True estimates of the dog population and its ecology and dynamics are needed to be able to plan and predict the effectiveness of further rabies eradication efforts in Bali. Past variation in estimates over time, all based on ratios of dogs to humans, is shown in Table 3. These estimates do not take account of the seasonal variation in dog population due to breeding seasons.

Table 3: Estimated Dog Population in Bali Dog : human ratio Est. dog pop’n Study area Source of Information 1 : 16 220,000 Asia WHO, 1984 1 : 4 875,000 Bali Teken Temadja, DGLS, 1984 1 : 25 140,000 Indonesia Sofyan Sudradjat, DGLS, 1992 1 : 6.5 540,000 Bali Yudhistira Foundation, Bali 1 : 8.27 425,000 Badung Badung Livestock Service, Feb 2009

Conclusion: An increase of effort by an order of magnitude will be needed in order to break the rabies transmission cycle and allow rabies to be eradicated from Bali. This will not happen without a major increase in resources, especially devoted to longer lasting dog vaccines and their application, reliable identification of vaccinated dogs, dog population ecology and population studies and control, and coordinated data analysis and control centre management between health and veterinary authorities. Without a further major and rapid response, rabies could become endemic in Bali, as it is elsewhere in most of Asia. This would lead to high ongoing control costs, potential damage to Bali’s tourism, human misery and deaths especially in poor children, and diversion of scarce resources from other high priority health and veterinary programs.

References: MacDiarmid, S.C. and Corrin, K.C. (1999) Case study: the risk of introducing rabies through the importation of dogs. Ministry of Agriculture, PO Box 2526 Wellington, New Zealand. Mahardika, IGNK (2009) Veterinary Faculty, Udayana University, (pers. comm). Putra, AAG, Dharma, DMN, Mahardika, IGNK,, Rompis, ALT, Muditha, IDM,, Asrama, IG, Sudarmono and Windarto, W. (2008). Rabies Eradication Strategy in South Kuta and Kuta Sub-Districts, Badung District, Bali Province. Bali Rabies Workshop, Directorate General of Livestock Services, Denpasar 2008. Sudradjat, S (1992) Applied Veterinary Epidemiology. Indonesian Ministry of Agriculture, pp 257-259. Teken,Temadja, IGN (1984) Rabies Policy on prevention, control and eradication of rabies in animals in Indonesia). WHO Rabies National Symposium, Denpasar, September 1984, pp 29-62.

Acknowledgments: Support and funding for this response is being provided by the Indonesian Ministry of Agriculture, Ministry of Health and relevant provincial and district governments for Bali, and the Australian Government.