an epidemic of canine rabies in central java, indonesia

Preventive Veterinary Medicine, 8 (1990) 295-303 295 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

Short C o m m u n i c a t i o n

An Epidemic of Canine Rabies in Central Java, Indonesia

D. WALTNER-TOEWS*, A. MARYONO, B.T. AKOSO, S. WISYNU and D.H.A. UNRUH

Yogyakarta Disease Investigation Centre, P.O. Box 79, Yogyakarta (Indonesia)

{Accepted for publication 1 June 1989)

ABSTRACT

Waltner-Toews, D., Maryono, A., Akoso, B.T., Wisynu, S. and Unruh, D.H.A., 1990. An epidemic of canine rabies in Central Java, Indonesia. Prey. Vet. Med., 8: 295-303.

An epidemic of rabies in the province of Central Java, Indonesia, in 1985-1986 was investigated. Eighty-nine percent of confirmed cases occurred in dogs, 70% of which were domestically owned. While the number of cases clearly exceeded that normally expected and thus constituted an epidemic, the actual risk of human exposure to a rabid animal bite during the peak epidemic period was only 1.5 per million for females and 3.4 per million for males. Males between the ages of 5 and 14 years were the group at greatest risk of being exposed to the bite of a rabid dog. In the most seriously affected district, the risk of a dog contracting rabies was estimated to be 105 per 100 000 during the epidemic period. No cases were reported in wildlife. The results of the investigation suggest methods by which rabies could be eradicated from Java.

INTRODUCTION

Indonesia consists of some 13 000 islands, of which ~ 1000 are inhabited. In general, islands to the east of the central island of Java, including the resort island of Bali, are considered to be free of rabies, while those to the north and west of Java are endemically infected. Java itself, with a human population of nearly 100 million people and a very dense domestic animal population, is not only geographically and demographically central to Indonesia, but is a micro- cosm of the rabies situation overall (see Fig. 1 ). The province of West Java is endemically plagued with rabies in both dogs and people, with ~ 10 canine cases being reported per month. Central Java and the District of Yogyakarta are usually free, but have, in the past, suffered periodic "invasions" from the

*Present address: Department of Population Medicine, University of Guelph, Guelph, Ont. N 1G 2Wl, Canada.

0167-5877/90/$03.50 © 1990 Elsevier Science Publishers B.V.

296 D. WALTNER-TOEWS ET AL.

west. East Java, within sight of Bali, is free of the disease. This is fortunate, since the primarily Hindu population of Bali is generally less open to government dog control measures than that of the primarily Muslim island of Java.

There was therefore great concern when, in September of 1985, cases of dogs biting humans, unexpectedly and without provocation, were reported from Wonogiri district in Central Java. Some of these dogs were killed and the brains submitted to the Yogyakarta Disease Investigation Centre (for histopathology) and/or to the Bio Farina laboratory in Bandung (for fluorescent antibody testing) (FAT) with a suspected diagnosis of rabies. This diagnosis was confirmed. The Yogyakarta laboratory also confirmed rabies, by histopathology, in one person who died after being bitten. Since no cases of rabies had been seen in this area for at least 10 years (Anon., 1975-1985 ), the number of cases seen was clearly in excess of normal expectancy and an epidemic was declared to be in progress.

M A T E R I A L S AND M E T H O D S

Members of the Yogyakarta Disease Investigation Centre in Central Java visited the offices of the provincial Department of Livestock Services in Cen- tral Java, the District of Yogyakarta, West Java, the District of Jakarta and East Java. Data were collected on animals suspected of being rabid and on the nature of human exposure, if this was reported. The staff also visited eight district offices in Central Java, two in East Java and one in Yogyakarta, which were considered to be high risk areas, either because they had reported confirmed cases or were in close proximity to areas which had reported confirmed cases, in order to collect data in more detail.

In the epidemic description and discussion which follows, we have focused on Central Java. However, in some instances the information from West Java is instructive when used as a comparison and is also presented. The investigation considered only those cases of rabies in animals that were confirmed by histopathology and/or FAT. We were unable to obtain data on the occurrence of human rabies for public presentation or on the vaccination status of the affected animals.

R E S U L T S

Of the 56 confirmed cases of rabies in Central Java between September 1985 and March 1986, 47 occurred in four contiguous districts in the eastern part of the province - - a day's travelling time by motor vehicle from the border with West Java (Fig. 1 ). Four cases of rabid dogs were reported in Cilacap, a port city near the border of West Java, three in a district adjacent to Cilacap and one each from the northern port cities of Tegal and Semarang.

Within the districts reporting cases in the eastern part of the province, the epidemic appeared to be moving north and west, in the valleys between the

CANINE RABIES IN CENTRAL JAVA 297

Primary focus of epidemic (47 cases)

Spi11-over from endemic area (7 cases)

One case also reported in Semarang, and in Tegal

Rabies-endemic

~ ~ ~ ~ Free

. . . . . . . " I> , . . ,~=~+:"~/ / / /~) E~st Java

Fig. 1. Geographic distribution of animal rabies cases in Central Java, 1985-1986.

mountains along the coast and on the border with East Java. Beginning in late November and early December, cases were reported from areas closer to the major city of Yogyakarta, capital of the District of Yogyakarta. In December, there was one confirmed case within the city limits. There was no evidence that the epidemic would either bypass the city and/or move into the country- side west of the city.

The epidemic started in mid-September 1985 and peaked in late November/ early December (Fig. 2). The government responded with a programme of control and containment which included the control of domestic dog, cat and monkey traffic on roads at the borders of affected districts, vaccination of domestic pets and elimination of stray animals. The Department of Livestock Services defined a domestic dog as one which had an identifiable owner; by exclusion, all other dogs were considered strays. Vaccination was provided to owners free of charge. All vaccinated pets were tagged. Shops which sold dog meat were closed. The programme for a particular district was continued until no cases of rabies in animals or people had been reported there for at least 4 months.

Any animal reported to have bitten humans or animals and suspected of being rabid was held in quarantine for 14 days before being released to the owner. If no owner could be identified at the time of capture, the animal was killed and the brain submitted to the Yogyakarta Disease Investigation Centre. Although no cases of rabies were reported in domestically owned monkeys in Central Java, such animals had been diagnosed as being rabid in West Java and were therefore included in the government control programme.

During the next 12 months, in Central Java, 210 425 domestic dogs, cats and monkeys were vaccinated; although an exact breakdown by species was not available to us, most ( > 90% ) of the vaccinates were reported to be dogs. At

298

8

4

Sept Oct Nov Dec Jan Feb Mar

D. WALTNER-TOEWS ET AL.

] Other

] Canine

CASES PER WEEK, SEPTEMBER i 1985 - MARCH 31 1986

Fig. 2. Animal rabies in Central Java, 1985-1986.

the same time, 61 048 dogs, cats and monkeys (again primarily dogs) were destroyed using rifles and strychnine. By January of 1986, the epidemic appeared to have abated. However, a few cases continued to be reported more than a year later. The question was raised: what more could the government do to stop the epidemic? The survey undertaken by the Yogyakarta Disease Investigation Centre was in part designed to answer this question.

Of the 56 confirmed rabid cases of animal rabies in Central Java, 89% were in dogs (50 animals), with the rest consisting of cats (1 animal) and cattle (5 animals).

Animal populations, including all domestically owned cats, dogs and monkeys, as well as all farm livestock, are enumerated for each village by the village head. These figures are then aggregated at the sub-district, district, provincial and national levels by the Department of Livestock Services. Estimates of dog populations arrived at in this manner were used to calculate the risk of a dog contracting rabies for the districts involved in the epidemic (Table 1). No cases in wildlife were reported from Central Java during the epidemic, nor is there any record of naturally occurring sylvatic rabies in that area. In fact, wildlife other than small rodents is rare in Central Java, due in part to the high human population density which, in some rural areas, is reported to be as high as 2000 people per square kilometre.

Among the dogs confirmed rabid, 70% were domestic dogs and 30% were stray dogs (Table 2). In the rabies-endemic area of West Java, 68% of con-


TABLE1

Districts in Central Java which reported confirmed cases of rabies in dogs, March 1985-March 19861

District Confirmed rabies cases Estimated dog populations

Wonogiri 21 ( 105 ) 20 000 Tegal 1 (83) 1 200 Sukoharjo 14 (56) 25 000 Karanganyar 5 (52) 9 569 Cilacap 4 (50) 8 000 Banyumas 3 (24) 12 751 Klaten 1 (5) 20 000 Semarang 1 (?) (?)

1Twenty-seven of the 35 districts and special areas of Central Java were not affected by the epidemic. Numbers in parentheses are prevalences in cases per 100 000 of the population. See text for how estimates of dog populations were obtained.

TABLE 2

Rabies status of stray vs. domestic biting dogs in Central and West Java, 1985-1986

Rabid Non-rabid 1 Total

Central Java Stray 15 (41%)2 22 37 Domestic 35 (14%) 221 256

Total 50 243 293

West Java Stray 28 (34%) 55 83 Domestic 13 (9%) 126 139

Total 41 181 222

1Non-rabid biting dogs were those that were reported for biting animals and/or humans, and were either held for the 14-day quarantine period and released to the owner, or died or were killed and tested negative by histopathology and FAT. 2Percent of row total. Mantel-Haenszel~ = 34.9, P<0.0001; odds ratio=4.7 (95% C.I., 2.8-7.7).

f i rmed cases were s t rays dur ing the same t ime period. In bo th the epidemic and endemic areas, if a s t ray dog behaved s t range ly and bit someone, it was 4-5 t imes more likely to be rabid t h a n if a domest ic dog bit someone (Table 2 ).

In the epidemic area, -~ 85% of cases in an imals involved h u m a n exposure; in the endemic area, this figure was 99.6%. I f h u m a n exposure was involved, a dog t h a t bit more t h a n one pe r son was 3.5 t imes more likely to be rabid t h a n if the dog only bi t one pe r son (Table 3).

N i n e t y pe rcen t of rabid dogs died wi th in the first week af ter first showing


TABLE 3

Relationship between the number of people bitten and the probability of a dog being rabid in Central Java, 1985-1986

No. ofpeople bi~en Rabid Non-rabid Total

> 1 12 21 33 1 31 188 219

Total 43 209 252

f f=8.5 , P<0.005, odds ratio=3.5 (95% C.I.,1.4-8.3).

TABLE 4

Association of the sex of human victims and exposure to rabid animal bites in Central Java, 1985- 1986

Exposed to rabid animal Population totals

Males 45 (0.34) 1 13 047 577

Females 24 (0.15) 15 573 373

1Numbers in parentheses are cases per 100 000 of the population.

TABLE 5

Attack rates, by age and sex, of human bite victims of rabid animals in Central Java, 1985-1986

Age group (years) Number reported bitten Population totals

Males 0-4 5-9

10-14 15-24 25-49

>~50

Females 0-4 5-9

10-14 15-24 25-49

>150

4 (0.20) 1 2 041 594 8 (0.47) 1 712 976 9 (0.57) 1 582 017 5 (0.20) 2 525 168

11 {0.30) 3 653 048 6 (0.39) 1 532 774

2 (0.10) 2 064 349 4 (0.23) 1 733 359 4 (0.25) 1 573 490 3 (0.11) 2 668 762 5 (0.13) 3 891 127 2 (0.06) 3 175 060

1Cases per 100 000 of the population.


clinical signs. However, a few dogs lived 14 days after first showing clinical signs and at least one dog which had bitten someone, but which was not reported to show any other clinical signs, was killed after 14 days and was found to be positive for rabies.

Males were more likely to be bitten than females, and children between the ages of 5 and 14 years were at higher risk than either infants or adults (Tables 4 and 5). In practically all age groups, males were twice as likely to be bitten by rabid dogs than females; in both males and females, the highest risk age group was between 5 and 14 years. The only exception to this was among people over 50 years, where males were more than 6 times more likely to be bitten than females (Table 5).

DISCUSSION

Given the usual incubation period for canine rabies (between 2 and 6 weeks; Kaplan, 1985), the shape of the epidemic curve and the geographic starting point, we hypothesize that a rabid dog was brought or came into Wonogiri district, near the East Java border, in late August or early September. It probably came from the endemic area of West Java. The index case probably bit several others - - enough to sustain animal-to-animal spread among the dog population where unvaccinated domestic dogs mix freely with strays. The direction of spread of the epidemic seemed to follow the main movement of animal and human traffic - - away from the mountains and toward the major market city of Yogyakarta. For this reason (the direction of animal move- ments) and because a number of rivers, some of them quite large, flow down from the central mountain range dividing the landscape west of Yogyakarta north to south, the epidemic was not expected to, and in fact did not, spill over into the area west of Yogyakarta. The cases which did occur in the western end of the province probably came from the adjacent endemic area in West Java, although we did not have data complete enough to establish this with certainty.

School-aged children, especially boys, were at greatest risk because they had both the time and the inclination to play with or tease dogs. Older men may have been involved in trying to capture suspect dogs, or may in fact be more inclined to play with dogs in their leisure time than older women.

A few previous reports have suggested that a dog can be rabid without showing any obvious clinical signs, or may develop some clinical signs and then recover (Bell et al., 1971; Kaplan, 1985). The dog reported in this study, which was killed after 14 days in quarantine and which was positive for rabies based on histology FAT, may have been such a case. Nevertheless, such cases, if they are indeed bona fide, are very rare and would be unlikely to affect the overall course of the epidemic or epidemic control programme. In any case, several factors need to be considered in making decisions on the fate of dogs in quarantine, including human exposure (How many were bitten? Were the bites provoked?) and the type of dog involved (stray or domestic), as well as the incidence of rabies in the area from which the dog was taken. We were unable


to determine in this study why the authorities finally decided to kill that particular dog or if indeed it represented a reporting error.

The data from this study suggest that schoolchildren, particularly boys, between the ages of 5 and 14 years might be an appropriate focus of a public education programme about rabies. This is consistent with other reports from Indonesia and elsewhere (Lakhanpal and Sharma, 1985; Soenardi, 1985). Older men in the village could perhaps be involved in this programme as well. One option would be to train the older men first and then use them as teachers in the school programmes.

In most parts of Indonesia, when rabies is seen, it is of the urban rather than the sylvatic type, i.e. the dog is the main animal involved in transmitt ing the infection to people and other animals. This is in keeping with what is seen in tropical countries throughout the world (Khan et al., 1986).

The island of Bali, which accounts for a large proportion of Indonesia's tour- ism-derived foreign exchange, is within sight of eastern Java. If rabies were to enter Bali, where a large dog population is allowed to run freely, the effect on the tourist industry, not to mention the effect on the populace, could be cata- strophic. The elimination of rabies from Java would drastically decrease the chance of this ever happening.

The results of this investigation emphasize that although an epidemic may be real and serious, the risk of any particular person or animal contracting disease may not be high and certainly not a cause for panic. For dogs, the risk of contracting rabies in the district most seriously affected was estimated to be about 1:1000 (Table 1). For humans, the risk was between i and 4:106 for exposure to a rabid dog (Table 4).

In both Central and West Java, domestic (owned) dogs far outnumber stray dogs. However, in West Java, there has long been a vaccination programme for domestic dogs because rabies is known to be endemic. Hence, most of the confirmed cases of rabies there occurred in stray dogs. The reverse is true for Central Java, where no ongoing vaccination programme is actively pursued and the majority of the confirmed cases occurred in domestic dogs.

Given the small actual numbers of stray dogs involved in the epidemic, vaccination of domestic dogs with a sufficiently potent vaccine could well be suf- ficent action to control the epidemic.

The very low level of rabies in Java, the apparent lack of a sylvatic reservoir and the involvement of dogs as the main source make the elimination of rabies, first from the epidemic zones and then from all of Java, a realistic goal. Obsta- cles to the realization of this goal are concerned with finances (lack of money to purchase or produce a high quality vaccine), and with political and social will.


ACKNOWLEDGEMENTS

Specia l t h a n k s go to t he en t i r e s t a f f o f t he Y o g y a k a r t a Disease I n v e s t i g a t i o n Cen t re , who ca r r i ed ou t t he w o r k for th i s s tudy, a n d to t he G o v e r n m e n t s of I n d o n e s i a a n d C anada , who p r o v i d e d t echn ica l a n d f inanc ia l suppor t .

REFERENCES

Anonymous, 1975-1985. Bulletin Epidemiologi Veteriner, Direktorat Kesehatan Hewan, Direk- torat Jendral Peternakan, Departemen Pertanian, Jakarta, Indonesia.

Bell, J.F., Gonzalez, M.A., Diaz, A.M. and Moore, G.J., 1971. Nonfatal rabies in dogs: Experimen- tal studies and results of a survey. Am. J. Vet. Res., 32: 2049-2058.

Kaplan, C., 1985. Rabies: a worldwide disease. In: P.J. Bacon (Editor), Population Dynamics of Rabies in Wildlife. Academic Press, London, pp. 1-21.

Khan, M.A., Diesch, S.L. and Goyal, S.M., 1986. Current status of rabies. Int. J. Zoon., 13: 215- 229.

Lakhanpal, U. and Sharma, R.C., 1985. An epidemiological study of 177 cases of human rabies. Int. J. Epidemiol., 14: 614-617.

Soenardi, 1985. A retrospective epidemiological study of rabies in animals and man in Central Sumatera, Indonesia. Fourth International Symposium on Veterinary Epidemiology and Eco- nomics, 18-22 November 1985, Singapore. Singapore Veterinary Association, 1986, pp. 220- 223.

an epidemic of canine rabies in central java, indonesia

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