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Rabies exposures in Thai children
Wilderness and Environmental Medicine, 12, 239 243 (2001)
ORIGINAL RESEARCH
Rabies exposures in Thai children CHITSANU PANCHAROEN, MD; USA THISYAKORN, MD; WEERASAK LAWTONGKUM, MD; HENRY WILDE, MD Department of Pediatrics, Chulalongkorn University Hospital (Drs Pancharoen, Thisyakorn, and Lawtongkum), and Queen Saovabha Memorial Institute, Thai Red Cross Society, Bangkok, Thailand (Dr Wilde).
Objective.—To determine the epidemiology of potential rabies exposures in Thai children. Methods.—The study was carried out at the Queen Saovabha Memorial Institute of the Thai Red Cross Society during 1 calendar year. All charts of victims aged 0 to 14 years with possible rabies exposures were retrospectively reviewed. Results.—Subjects were 2622 children, with a male to female ratio of 1.6:1 and a mean age of 6.7 years (range, 2 months to 14 years). Most exposures (86.3%) were related to dogs. The most common site of exposure was the lower extremity. The majority of exposures occurred in or around the home and as the consequence of unprovoked attacks rather than provoked attacks. Antirabies vaccines were given in all cases: 68.4% using the Thai Red Cross intradermal route, and 31.6% using the intramuscular route. Rabies immunoglobulin (RIG) was prescribed in 57.5% of children; 35.2% received human RIG (HRIG), and 22.3% received purified equine RIG (ERIG). Conclusions.—This study confirms that rabies exposures, especially in children, are an important public health problem in Thailand. The reduced-dose, multiple-site intradermal rabies vaccine method and ERIG in place of HRIG reduce the cost of treatment. Key words: rabies exposure, animal bites, dog bites, children
Introduction
Methods
Animal rabies and animal bites are serious public health problems in Thailand. As in the United States, reported cases of human rabies deaths are rare, but the number of rabies-exposed victims who received rabies vaccines and immunoglobulin remains high.1,2 The Queen Saovabha Memorial Institute (QSMI) operates as the principal rabies prevention clinic for the Bangkok metropolitan area. The majority of patients who attend QSMI are poor and are probably representative of those who attend public health institutions throughout Thailand and other developing countries where canine rabies is prevalent. Children are a population group at high risk of rabies exposure and rabies. Approximately one-third of Thai children are bitten by dogs at least once by the age of 15.3 This study was conducted to delineate the epidemiology of potential rabies exposures in Thai children.
This study was carried out retrospectively from January 1 to December 31, 1994. All victims aged 0 to 14 years who visited QSMI with potential exposure to rabies were enrolled. Data collection was by chart review. Information collected included age, sex, month of exposure, number of days before presenting, site of exposure, wound characteristics, type and characteristics of involved animal, location where exposure took place, circumstances of animal attack, antirabies vaccine and route of injection, use of rabies immunoglobulin (RIG), adverse reactions, and outcome.
Corresponding author: Chitsanu Pancharoen, MD, Department of Pediatrics, Chulalongkorn Hospital, Rama IV Rd, Bangkok 10330, Thailand ([email protected]).
Results Of 9829 possible rabies-exposed victims treated at QSMI in 1994, 2622 cases (26.7%) were children. There were 1622 males and 1000 females, with a male to female ratio of 1.6:1. Ages ranged from 2 months to 14 years, with a mean of 6.7 years and peaks of 2 to 3 and 3 to 4 years (Figure 1). There were 2 peak incidences during the school holidays (March–April and October–
240
Pancharoen et al
Figure 1. Victims, classified by age.
November) (Figure 2). Seventy-six percent of the victims visited QSMI within 5 days after the exposure. Common sites of exposures were the lower (39.8%) and upper (20.2%) extremities (Table 1). Wound characteristics were mostly lacerations (26.8%) and abrasions (26.1%) (Table 2). The most common responsible mammals were dogs (86.3%) (Table 3). Four-hundred sixty-seven tested animals were found to have rabies at necropsy by fluorescent antibody testing: 440 dogs, 17 cats, 2 squirrels, 2 rabbits, and 6 humans. However, most of the responsible
Figure 2. Victims, classified by month of exposure.
dogs and cats were stray and, therefore, not available for observation or laboratory examination. Locations where exposures took place were mostly in the house compound (35.5%) or around the home (27.1%) (Figure 3). Unprovoked attacks were approximately 4 times more common than provoked attacks. It was often difficult to define what was provoked. For example, walking close to a hidden nest with puppies may have been a provoked event to the mother dog but was not recognized as such by the patient.4 Antirabies vaccinations were offered in all cases, even
Rabies exposures in Thai children
241
Table 1. Sites of exposures (in order of frequency)
Table 2. Wound characteristic (in order of frequency)
Sites of exposures
No.
Percentage
Characteristics
Lower extremity Upper extremity No sites Head-face-neck ⬎1 site Trunk—back Buttock—genitalia Not mentioned Total
1043 530 402 310 105 99 92 41 2622
39.8 20.2 15.3 11.8 4.0 3.8 3.5 1.6 100.0
for those who were not considered World Health Organization Category II or III exposures.5 They were often given ‘‘preexposure’’ vaccine series when the source of the exposure turned out to be petting the animal (Category I). We thus administered 89.3% postexposure, 5.5% preexposure, and 5.2% booster regimens (in subjects who had a prior rabies vaccine history). Vaccinations were administered using the intradermal (68.4%) and intramuscular (31.6%) routes. In 1510 victims (57.5%), RIG was used. Equine RIG (ERIG) was given to 586 victims and human RIG (HRIG) to 924 victims. The HRIG used was manufactured by the National Blood Center of the Thai Red Cross Society. The RIG was injected into or around wounds, and, if any remained, it was injected intramuscularly elsewhere. Adverse reactions from vaccines and RIG included 3 cases of local erythema from intramuscular vaccine (1), HRIG (1), and ERIG (1) and 1 case of generalized erythema from ERIG (minor serum sickness-like reaction). There were no reports of fever, serum sickness, or other serious adverse effects from vaccines or RIG. This study thus also documented serum sickness after purified ERIG as a very rare event in children under 14 years (1:586). There were no rabies deaths in this group of patients. Discussion This study revealed that 26.7% of all rabies-exposed victims were children, which approximates the figure of 25.8% reported in Australia in 1980.6 The victims were predominately male and 2 to 4 years of age. This may be attributed to increased risk-taking behavior in boys. Children aged 2 to 4 years are able to reach animals but unable to protect themselves well from bites. The 2 peak incidences from March through April and from October through November are school holidays for Thai children. The majority of victims visited the clinic within a few
Laceration Abrasion ⬎1 type Puncture No wound Bite, no wound Scratch Mucous contact with saliva Lick on intact skin Lick on broken skin Not mentioned Total
No.
Percentage
704 684 331 322 291 108 64 35 33 26 24 2,622
26.8 26.1 12.6 12.3 11.1 4.1 2.4 1.3 1.2 1.0 0.9 100.0
days after the attack. This suggests an awareness on the part of patients/families of rabies and availability of postexposure treatment and was also found in a previous study.7 Previous studies7–9 and our study found the lower extremity to be the most common site of exposure. Lacerations were the most common forms of wounds and represent the more severe form of bite injuries. Our study disclosed that dogs, cats, and rats were the 3 most common mammals responsible for bites in Thai children with potential rabies exposure. Dogs were the most common mammals found to have rabies. Dogs and cats are pets with which children often play. Rats, however, are inappropriate animals in the environment for children. They are extremely unlikely to be rabid; nevertheless, we have encountered large rats with confirmed rabies in Bangkok. Previous studies from other countries10–12 and our study showed that potential rabies exposure occurred Table 3. Sources of potential rabies exposure Type of mammals
No.
Percentage
Dogs Cats Rats Monkeys Humans* Squirrels Gibbons Rabbits Others Total
2263 255 41 26 13 10 5 3 6 2622
86.3 9.7 1.6 1.0 0.5 0.4 0.2 0.1 0.2 100.0
* Close contacts with human rabies patients and possible mucous membrane exposure.
242
Pancharoen et al
Figure 3. Victims, classified by location where exposed.
mostly in or around the house and less commonly at school or on the street. However, Bhanganada et al8 found that 45% of victims received injuries on streets. Those differences in locations may be due to the fact that the enrolled victims in the latter report included more adults who had gone to work. Intradermal rabies postexposure vaccination results in adequate neutralizing antibody and is at least as effective as the intramuscular route.13 The expense of the former route is 2.5 times less than that of the latter. This study suggests that purified ERIG can be administered safely and effectively, particularly in children. It is also more economical than HRIG. We would have spent 7.8 times more funds (16 US$ for 5 mL of ERIG and 65 US$ for 2 mL of HRIG) on cases receiving ERIG if HRIG had been used instead.
References 1. Annual Epidemiological Surveillance Report, Division of Epidemiology. Ministry of Public Health, Thailand; 1989– 1998. 2. Centers for Disease Control and Prevention. Human rabies prevention—United States, 1999: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR. 1999;48(RR-1):1–2. 3. Wilde H, Chutivongse S, Tepsumethanon W, Choomkasien P, Polsuwan C, Lumlertdacha B. Rabies in Thailand: 1990. Rev Infect Dis. 1991;13:644–652. 4. Siwasontiwat D, Lumlertdacha B, Polsuwan C, Hemachudha T, Chutivongse S, Wilde H. Rabies: is provocation of the biting dog relevant for risk assessment? Trans Roy Soc Trop Med Hyg. 1992;86:443. 5. World Health Organization Expert Committee on Rabies.
Rabies exposures in Thai children
6.
7.
8.
9.
Eighth report. WHO Technique Report Series 824. Geneva: World Health Organization; 1998. Nixon J, Pearn J, McGarn F. Dog bite injuries to children: potential rabies threat to Australia. Med J Aust. 1980;1: 175–176. Swaddiwuthipong W, Chutivongse S, Kulganchavin C, et al. Epidemiology of human rabies post-exposure prophylaxis, Bangkok 1984. Commun Dis J. 1986;12:159–176. Bhanganada K, Wilde H, Sakolsataydorn P, Oonsambat P. Dog-bite injuries at a Bangkok teaching hospital. Acta Trop. 1993;55:249–255. Beck AM, Loring H, Lockwood R. The ecology of dog
243
10.
11. 12. 13.
bite injury in St Louis, Missouri. Public Health Rep. 1975; 90:262–267. Lauer EA, White WC, Lauer BA. Dog bites. A neglected problem in accident prevention. Am J Dis Child. 1982; 136:202–204. Avner JR, Baker MD. Dog bites in urban children. Pediatrics. 1991;88:55–57. Kizer KW. Epidemiologic and clinical aspects of animal bite injuries. JACEP. 1979;8:134–141. World Health Organization. Recommendations on Rabies Postexposure Treatment and the Correct Technique of Intradermal Immunization against Rabies. Geneva: WHO/ EMC/Zoo 96.6; 1996.
ORIGINAL RESEARCH
Rabies exposures in Thai children CHITSANU PANCHAROEN, MD; USA THISYAKORN, MD; WEERASAK LAWTONGKUM, MD; HENRY WILDE, MD Department of Pediatrics, Chulalongkorn University Hospital (Drs Pancharoen, Thisyakorn, and Lawtongkum), and Queen Saovabha Memorial Institute, Thai Red Cross Society, Bangkok, Thailand (Dr Wilde).
Objective.—To determine the epidemiology of potential rabies exposures in Thai children. Methods.—The study was carried out at the Queen Saovabha Memorial Institute of the Thai Red Cross Society during 1 calendar year. All charts of victims aged 0 to 14 years with possible rabies exposures were retrospectively reviewed. Results.—Subjects were 2622 children, with a male to female ratio of 1.6:1 and a mean age of 6.7 years (range, 2 months to 14 years). Most exposures (86.3%) were related to dogs. The most common site of exposure was the lower extremity. The majority of exposures occurred in or around the home and as the consequence of unprovoked attacks rather than provoked attacks. Antirabies vaccines were given in all cases: 68.4% using the Thai Red Cross intradermal route, and 31.6% using the intramuscular route. Rabies immunoglobulin (RIG) was prescribed in 57.5% of children; 35.2% received human RIG (HRIG), and 22.3% received purified equine RIG (ERIG). Conclusions.—This study confirms that rabies exposures, especially in children, are an important public health problem in Thailand. The reduced-dose, multiple-site intradermal rabies vaccine method and ERIG in place of HRIG reduce the cost of treatment. Key words: rabies exposure, animal bites, dog bites, children
Introduction
Methods
Animal rabies and animal bites are serious public health problems in Thailand. As in the United States, reported cases of human rabies deaths are rare, but the number of rabies-exposed victims who received rabies vaccines and immunoglobulin remains high.1,2 The Queen Saovabha Memorial Institute (QSMI) operates as the principal rabies prevention clinic for the Bangkok metropolitan area. The majority of patients who attend QSMI are poor and are probably representative of those who attend public health institutions throughout Thailand and other developing countries where canine rabies is prevalent. Children are a population group at high risk of rabies exposure and rabies. Approximately one-third of Thai children are bitten by dogs at least once by the age of 15.3 This study was conducted to delineate the epidemiology of potential rabies exposures in Thai children.
This study was carried out retrospectively from January 1 to December 31, 1994. All victims aged 0 to 14 years who visited QSMI with potential exposure to rabies were enrolled. Data collection was by chart review. Information collected included age, sex, month of exposure, number of days before presenting, site of exposure, wound characteristics, type and characteristics of involved animal, location where exposure took place, circumstances of animal attack, antirabies vaccine and route of injection, use of rabies immunoglobulin (RIG), adverse reactions, and outcome.
Corresponding author: Chitsanu Pancharoen, MD, Department of Pediatrics, Chulalongkorn Hospital, Rama IV Rd, Bangkok 10330, Thailand ([email protected]).
Results Of 9829 possible rabies-exposed victims treated at QSMI in 1994, 2622 cases (26.7%) were children. There were 1622 males and 1000 females, with a male to female ratio of 1.6:1. Ages ranged from 2 months to 14 years, with a mean of 6.7 years and peaks of 2 to 3 and 3 to 4 years (Figure 1). There were 2 peak incidences during the school holidays (March–April and October–
240
Pancharoen et al
Figure 1. Victims, classified by age.
November) (Figure 2). Seventy-six percent of the victims visited QSMI within 5 days after the exposure. Common sites of exposures were the lower (39.8%) and upper (20.2%) extremities (Table 1). Wound characteristics were mostly lacerations (26.8%) and abrasions (26.1%) (Table 2). The most common responsible mammals were dogs (86.3%) (Table 3). Four-hundred sixty-seven tested animals were found to have rabies at necropsy by fluorescent antibody testing: 440 dogs, 17 cats, 2 squirrels, 2 rabbits, and 6 humans. However, most of the responsible
Figure 2. Victims, classified by month of exposure.
dogs and cats were stray and, therefore, not available for observation or laboratory examination. Locations where exposures took place were mostly in the house compound (35.5%) or around the home (27.1%) (Figure 3). Unprovoked attacks were approximately 4 times more common than provoked attacks. It was often difficult to define what was provoked. For example, walking close to a hidden nest with puppies may have been a provoked event to the mother dog but was not recognized as such by the patient.4 Antirabies vaccinations were offered in all cases, even
Rabies exposures in Thai children
241
Table 1. Sites of exposures (in order of frequency)
Table 2. Wound characteristic (in order of frequency)
Sites of exposures
No.
Percentage
Characteristics
Lower extremity Upper extremity No sites Head-face-neck ⬎1 site Trunk—back Buttock—genitalia Not mentioned Total
1043 530 402 310 105 99 92 41 2622
39.8 20.2 15.3 11.8 4.0 3.8 3.5 1.6 100.0
for those who were not considered World Health Organization Category II or III exposures.5 They were often given ‘‘preexposure’’ vaccine series when the source of the exposure turned out to be petting the animal (Category I). We thus administered 89.3% postexposure, 5.5% preexposure, and 5.2% booster regimens (in subjects who had a prior rabies vaccine history). Vaccinations were administered using the intradermal (68.4%) and intramuscular (31.6%) routes. In 1510 victims (57.5%), RIG was used. Equine RIG (ERIG) was given to 586 victims and human RIG (HRIG) to 924 victims. The HRIG used was manufactured by the National Blood Center of the Thai Red Cross Society. The RIG was injected into or around wounds, and, if any remained, it was injected intramuscularly elsewhere. Adverse reactions from vaccines and RIG included 3 cases of local erythema from intramuscular vaccine (1), HRIG (1), and ERIG (1) and 1 case of generalized erythema from ERIG (minor serum sickness-like reaction). There were no reports of fever, serum sickness, or other serious adverse effects from vaccines or RIG. This study thus also documented serum sickness after purified ERIG as a very rare event in children under 14 years (1:586). There were no rabies deaths in this group of patients. Discussion This study revealed that 26.7% of all rabies-exposed victims were children, which approximates the figure of 25.8% reported in Australia in 1980.6 The victims were predominately male and 2 to 4 years of age. This may be attributed to increased risk-taking behavior in boys. Children aged 2 to 4 years are able to reach animals but unable to protect themselves well from bites. The 2 peak incidences from March through April and from October through November are school holidays for Thai children. The majority of victims visited the clinic within a few
Laceration Abrasion ⬎1 type Puncture No wound Bite, no wound Scratch Mucous contact with saliva Lick on intact skin Lick on broken skin Not mentioned Total
No.
Percentage
704 684 331 322 291 108 64 35 33 26 24 2,622
26.8 26.1 12.6 12.3 11.1 4.1 2.4 1.3 1.2 1.0 0.9 100.0
days after the attack. This suggests an awareness on the part of patients/families of rabies and availability of postexposure treatment and was also found in a previous study.7 Previous studies7–9 and our study found the lower extremity to be the most common site of exposure. Lacerations were the most common forms of wounds and represent the more severe form of bite injuries. Our study disclosed that dogs, cats, and rats were the 3 most common mammals responsible for bites in Thai children with potential rabies exposure. Dogs were the most common mammals found to have rabies. Dogs and cats are pets with which children often play. Rats, however, are inappropriate animals in the environment for children. They are extremely unlikely to be rabid; nevertheless, we have encountered large rats with confirmed rabies in Bangkok. Previous studies from other countries10–12 and our study showed that potential rabies exposure occurred Table 3. Sources of potential rabies exposure Type of mammals
No.
Percentage
Dogs Cats Rats Monkeys Humans* Squirrels Gibbons Rabbits Others Total
2263 255 41 26 13 10 5 3 6 2622
86.3 9.7 1.6 1.0 0.5 0.4 0.2 0.1 0.2 100.0
* Close contacts with human rabies patients and possible mucous membrane exposure.
242
Pancharoen et al
Figure 3. Victims, classified by location where exposed.
mostly in or around the house and less commonly at school or on the street. However, Bhanganada et al8 found that 45% of victims received injuries on streets. Those differences in locations may be due to the fact that the enrolled victims in the latter report included more adults who had gone to work. Intradermal rabies postexposure vaccination results in adequate neutralizing antibody and is at least as effective as the intramuscular route.13 The expense of the former route is 2.5 times less than that of the latter. This study suggests that purified ERIG can be administered safely and effectively, particularly in children. It is also more economical than HRIG. We would have spent 7.8 times more funds (16 US$ for 5 mL of ERIG and 65 US$ for 2 mL of HRIG) on cases receiving ERIG if HRIG had been used instead.
References 1. Annual Epidemiological Surveillance Report, Division of Epidemiology. Ministry of Public Health, Thailand; 1989– 1998. 2. Centers for Disease Control and Prevention. Human rabies prevention—United States, 1999: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR. 1999;48(RR-1):1–2. 3. Wilde H, Chutivongse S, Tepsumethanon W, Choomkasien P, Polsuwan C, Lumlertdacha B. Rabies in Thailand: 1990. Rev Infect Dis. 1991;13:644–652. 4. Siwasontiwat D, Lumlertdacha B, Polsuwan C, Hemachudha T, Chutivongse S, Wilde H. Rabies: is provocation of the biting dog relevant for risk assessment? Trans Roy Soc Trop Med Hyg. 1992;86:443. 5. World Health Organization Expert Committee on Rabies.
Rabies exposures in Thai children
6.
7.
8.
9.
Eighth report. WHO Technique Report Series 824. Geneva: World Health Organization; 1998. Nixon J, Pearn J, McGarn F. Dog bite injuries to children: potential rabies threat to Australia. Med J Aust. 1980;1: 175–176. Swaddiwuthipong W, Chutivongse S, Kulganchavin C, et al. Epidemiology of human rabies post-exposure prophylaxis, Bangkok 1984. Commun Dis J. 1986;12:159–176. Bhanganada K, Wilde H, Sakolsataydorn P, Oonsambat P. Dog-bite injuries at a Bangkok teaching hospital. Acta Trop. 1993;55:249–255. Beck AM, Loring H, Lockwood R. The ecology of dog
243
10.
11. 12. 13.
bite injury in St Louis, Missouri. Public Health Rep. 1975; 90:262–267. Lauer EA, White WC, Lauer BA. Dog bites. A neglected problem in accident prevention. Am J Dis Child. 1982; 136:202–204. Avner JR, Baker MD. Dog bites in urban children. Pediatrics. 1991;88:55–57. Kizer KW. Epidemiologic and clinical aspects of animal bite injuries. JACEP. 1979;8:134–141. World Health Organization. Recommendations on Rabies Postexposure Treatment and the Correct Technique of Intradermal Immunization against Rabies. Geneva: WHO/ EMC/Zoo 96.6; 1996.