6 o5
RABIES IN NEW YORK CITY, WITH NEW GUIDELINES FOR PROPHYLAXIS
JOHN S. MARR, M.D., M.P.H. Director, Bureau of Preventable Diseases
ALAN M. BECK, Sc.D. Director, Bureau of Animal Affairs Department of Health, City of New York New York, N.Y.
INCEthe early part of this century the Department of Health of the City of New York has collected a variety of information concerning animal bites and rabies. The data include case reports and statistics of animal bites, rabies in animals, and rabies in man; the numbers of animals examined for rabies; and the number of individuals per year given prophylactic treatment with antirabies immunizations. These data were reviewed recently in order to determine whether the present national recommendations for prophylaxis of rabies should be modified for persons bitten by indigenous animals in New York City. An analysis was made as to the frequency and type of animal bite, the number of documented rabid animals, the number of animal brains routinely examined for rabies, and the number of individuals receiving immunizations against rabies at the Department of Health's immunization clinics -from 1935 to the present. This information was presented to an Expert Advisory Committee on Rabies convened by the Commissioner of Health in September 1974. The committee confirmed the observation of Department of Health officials that terrestrial rabies has ceased to exist within the city of New York and that recommendations for rabies prophylaxis in bitten persons be changed accordingly. A summary of these findings has been published.' RESULTS Animal bites. Since i908 the Department of Health has kept accurate records of the number of animal bites in New York City during each year. These records were recently summarized.2 The number of reported bite episodes has averaged 32,735 per year during the last two Vol. 52, No. 5, June 1976
6o6
J. S. MARR AND A. M. BECK
CASES 40000
35000
30000
25000
J
20000 1960
1965
1975
1970
YEAR
Fig. 1. Reported cases of dog bite in New York City, 1960 to 1975.
Bull. N. Y. Acad. Med.
6 07
RABIES IN NEW YORK CITY YORK
607
CITY
500
400
0
Dogs
a
Other Animals One horse - 1913 Cats - 1913-1948 Bats - 1959-1975
300
w
200
0 '4
w
0.
ACd
I.[00
I-'
'1
1
[1 H
11
Ii
'4
.0
75
-
50
-
-
25
-
0
I 1. 1" .AX
1910
I
1920
I
I
I
1930
I
I
I
_
1 1940 YEAR
* X A-L
I bd rr l
1950
r--
I 1960
1
_l-
1970
Fig. 2. Number of rabid animals reported in New York City, 1908 to 1975.
decades. The majority of these bites have been from dogs, and the number of dog bites has remained relatively stable in the last five years (Figure i). Rabies in animals. The history of rabies in animals in New York City was summarized by Asedo in I 966.3 He noted that the last case of rabies to be found in a terrestrial animal indigenous to the city occurred in 1954. Since i966 no new rabid terrestrial animals have been Vol. 52, No. 5, June 1976
60o8
15
.
14
-
l-In|ZSz-*Heb|*=w J. S.
13 -
MARR AND A. M. BECK BECK MARR
AND
A.
M.
Case acquired in the City
12
-
11
-
10
-
Case acquired out of town
9sP% 8
-
7
-
'4
a 0
a 6-
5432I-
I,IIIII a
0 --
TI
1905 1910
I
I
1915
I
4I
tihl
I.
SoI III
I
II
I
I
I
1920
1925
1930
.I
1935
1940
I
I
I
I
I,
I
1945
1950
1955
1960
1965
1970
YEAR
Fig. 3. Reported
cases
of human rabies in New York City, 1905 to 1970.
identified within the city, although nine rabid bats have been reported in the city since I959 (Figure 2). Human rabies. Since I905 a total of 98 cases of human rabies has been reported in New York City. Eighty-nine of these were acquired from animals within the city, and the remaining nine resulted from animal bites incurred outside the city. The last case of human rabies acquired from the bite of an indigenous city animal occurred in I944. Bull. N. Y. Acad. Med.
609
RABIES IN NEW YORK CITY
800
-
700
-
600
-
4
A
500-
a
0
.44
21 400
-
'.4
*
Af
One Positive Bat
-
NYC
+ One Positive Animal - Outside
of NYC
300
*
m
*
*
*
*
*
-
*
I-
200 -
100 -
*
+I
+
+
*
*
+
+
*
* *
*
+
*
I
0
1959
1961
1963
1965
1967
1969
1971
1973
1975
YEAR
Fig. 4. Animal brains examined for rabies in New York City (NYC), 1959 to 1975.
Vol. 52, No. 5, June 1976
6 io
J. S. MARR AND A. M. BECK
3500
3000
2500-
2000
15000-
100
1500
1935
1940
1945
1950
1955
1960
1965
1970
1975
YEAR
Fig. 5. Persons receiving antirabies prophylactic treatment in New York City, 1935 to 1975.
The last instance of human rabies resulting from a bite occurring outside the city was in I967 (Figure 3). Examnation of animals for rabies. Since 1959 an average of 634 animal brains has been examined yearly for rabies virus. With the exception of the rabid bats mentioned above and the brains of nonurban animals, there have been no positive brain preparations in city animals during this period (Figure 4). In the same period a total of 250,000 animals has been examined by city veterinarians for clinical signs compatible with rabies; no positive findings resulted. Bull. N. Y. Acad. Med.
RABIES IN NEW YORK CITY
RABIES
6I I
6i
i
Antirabies treatments. The number of persons receiving antirabies prophylactic treatment in New York City has been recorded regularly since I935. The number of persons receiving antirabies prophylaxis has averaged 437 per year during the past to years (Figure 5). DISCUSSION Records of the number of animal bites have demonstrated a large number of incidents in each year (Figure i). The fact that only a fraction of bite victims receive antirabies immunization is indirect evidence of the absence of the disease in animals indigenous to the city. Direct evidence of the absence of rabies virus in city animals is provided by specific brain examinations in animals destroyed by shelters and forwarded to the Department of Health's Bureau of Laboratories for routine examination. The reliability and sensitivity of the testing procedure, which employs fluorescent antibody techniques, has been substantiated by the occasional positive finding in the brains of bats and extra-urban animals (Figure 4). In New York City, as in the rest of the country, the animal responsible for most bites is the dog. This problem appears to be increasing.2' "4'5 Most of the dogs identified as biters within the city are owned animals. In 1975 almost 33,ooo dog bites were reported; 62% were contracted from dogs that were owned and observable. Approximately i9% of the remaining dogs were owned but were not observable because of noncompliance with the procedure of reporting or because of denied ownership. The remaining i9% of bites were from dogs which did not have an identified owner or were ownerless strays. Most owned dogs either are born within the city or are acquired as puppies from pet shops or kennels where vaccination against rabies is a common practice. These owned dogs are not exposed to potentially rabid animals within the city or in kennels which may be outside the city. The likelihood of an owned dog acquiring rabies is small. Although there are an estimated 200,000 stray dogs in New York City, most of these animals were owned at one time or were bred by other dogs within the city. Stray and loose domestic animals have little contact with the few wild animals resident within the city. In addition, the city is virtually isolated from the continental land mass, Bronx County being the city's only land connection. During the past IO years there have been no documented cases of animal rabies within ioo miles of Vol. 52, No. 5, June 1976
6I2
J.
J.
MARR AND AND A. M. BECK S. MARR S.
the upstate counties which are contiguous with the city or within 50 miles of the city in the states which are separated from the city by bodies of water. Ongoing surveillance for the presence of rabies in local animal populations of adjoining states is reviewed quarterly. It would appear from these facts that the city of New York and surrounding territories are free of terrestrial rabies. Importation of the disease by migratory animals is improbable; if it occurred, it would be detected early. In a later paragraph we suggest that recommendations for bite victims be changed accordingly. Although more than 3,000 rabid dogs have been reported in New York City since i908, there have been only 52 confirmed rabid cats and one rabid horse (Figure 2). The last rabid cat was discovered in the borough of Richmond in 1948. The rabid horse was reported in Manhattan in 1913. The peak years for rabies in cats (1913, I926-i930, 1938-i940) were also times in which the rabid dog populations had increased, hence the feline rabies probably represented a result of infections from dogs. With the disappearance of rabies in the canine population, the likelihood of rabies occurring in either the feline or small livestock populations within the city appears to be small. Bites from such animals are now being treated by the methods used for dog bites. Rabies has never been recorded in any rodents, lagomorphs, or insectivores within the city. Although a tiny percentage of rodents in the western portions of the United States may harbor rabies virus, these animals are not considered a source of infection in any part of the eastern United States.7 Our recommendations reflect this. Judging from reports of bites, there are many unusual, wild, or exotic pet animals in the city of New York. Many of these animals belong to public and private zoos which allow human and animal contact. Others are owned by private citizens, legally or illegally. The New York City Health Code proscribes ownership of "an animal of species which is wild, ferocious, fierce, dangerous or naturally inclined to do harm."8 Nevertheless, it is apparent through yearly reviews of bites by exotic animals that man's desire to own unusual animals is limited only by the number of genera available for purchase. In I974 there were i i I bites by wild or exotic animals. Most of these were from monkeys. Since the efficacy of rabies vaccine in animals other than dogs, cats, and livestock is questionable, and since the origin of many owned exotic mammals is often unknown, animals within this category should be Bull. N. Y. Acad. Med.
RABIES IN NEW YORK CITY
RABIES
IN
NEW
YORK
6I3
6i
3
observed closely for Io days for signs compatible with rabies. If signs of the disease develop or brain examination is positive, antirabies prophylaxis should be instituted immediately. If the biting animal escapes or is not available for observation, the treatment should begin as soon as possible. It should be recalled that in the entire experience of the Department of Health's records of rabid animals, -there have never been reports of rabies in animals other than dogs, cats, bats, and one horse. Since I959, when the Department of Health initiated brain examination of all captured bats, only nine bats were found to be positive out of a total of 689 examined (Figure 2). All positive findings in bats were made in late July through early September, and mostly in migratory species, e.g., Lasiurus borealis and L. cinereus. Even with this low frequency, all bat bites should be treated immediately unless the animal is captured and is shown to be free of rabies by fluorescent antibody examination within 24 hours. In cases in which the bat has escaped, prophylactic treatment should be given immediately. The fear of rabies usually has created anxiety in persons bitten by almost any animal. On many occasions laymen and physicians have queried the Department of Health as to the presence of rabies in nonmammalian vertebrates, such as birds, reptiles, and fish. There is no evidence that rabies has ever been contracted from the bite of a nonmammalian animal. Therefore, we do not recommend prophylactic treatment for their bites nor do we examine any of these animals for rabies. As a result of the above analyses, the Department of Health has developed specific guidelines for the management of bites incurred from indigenous animals. These guidelines have recently been issued to physicians in the rabies clinic of the Department of Health. In the past these physicians have used their knowledge of the incidence of the disease in urban animals in counseling bitten persons as to the need for prophylactic treatment. However, since the Department of Health's former guidelines were based on national guidelines, many patients continued to receive prophylaxis. This is evident from an analysis of the records of treatment given in I975. In the first six months of the year I92 persons received prophylactic treatment. In early July 1975 a joint directive from the Bureau of Preventable Diseases and the Bureau of Animal Affairs informed clinic physicians that patients bitten by domestic terrestrial animals within the city need not receive antirabies prophylaxis. In the second six months of 1975 the number of persons Vol. 52, No. 5, June 1976
6 I4
J. S. MARR
AND A. M. BECK
TABLE I. GUIDELINES FOR PROPHYLAXIS OF RABIES IN NEW YORK CITY
Animal
Special Prophylactic recommendation considerations
1) Dog, cat, livestock,
rodent, lagomorph, rp insectivore a) Owned b) Unowned or escaped 2) Wild or exotic mammal a) Owned b) Unowned or escaped 3) Bats 4) Nonmammalian vertebrate
None None
Note 1 Note 2
None Treat Treat None
Note 1 Note 3 Note 3 None
Note 1-Unless the animal has arrived recently from an area in which rabies is endemic or the animal demonstrates behavior compatible with rabies within 10 days after the bite. Note 2-Unless the animal clearly demonstrated behavior compatible with rabies at the time of the bite. Note 3-If the animal was captured, prophylactic treatment can await the results of brain examination but prophylaxis should not be postponed more than 24 hours after the bite.
receiving it totalled only i8, although in past years a greater number would have been expected in the second half of the year. Of the i8 persons who received prophylaxis, nine had been bitten by animals outside the city or country. National guidelines were followed in these cases.9 The remaining persons received prophylaxis as a result of unusual circumstances accompanying the bite or through failure of clinic physicians to follow the new guidelines of the city. Probably no more than a few dozen bitten persons will really need antirabies prophylaxis in any future year. These will be persons bitten by bats or other exotic animals within the city or bitten by animals outside the city or country. The new recommendations for antirabies prophylaxis of bitten persons are outlined below (Table I). A schedule also is presented which is similar to that recommended by the Center for Disease Control (Table II).9 SUMMARY AND RECOMMENDATIONS A review of records of animal rabies and human rabies in New York City has revealed an absence of this disease in terrestrial animals for more than 20 years. Ongoing surveillance of captured and killed aniBull. N. Y. Acad. Med.
RABIES IN NEW YORK CITY
6I5
TABLE II. SCHEDULE OF PROPHYLACTIC TREATMENT Day 1 1) Human rabies immune globulin 20 I.U./kg. of body weight intramuscularly (ideally, 1/2 dose should be injected in and around the site of the bite) 2) Duck embryo vaccine-first dose subcutaneously in arm, leg, buttock, or abdomen
Days 2 to Duck Day 31 Duck Day 41 Duck
21 embryo vaccine-first booster subcutaneously, rotating injection sites
embryo vaccine-first booster subcutaneously
embryo vaccine-second booster subcutaneously
mals has shown that the bat is the only continuing source of the infection within the city, although the potential of imported rabies among exotic animals kept as pets has been recognized. Antirabies prophylaxis after dog and cat bites may have been necessary in previous years. However, with the disappearance of the disease in terrestrial animals within the city new recommendations are needed. These recommendations have been based on careful analysis of the history of rabies in New York City and are summarized below: i) Owned, domesticated city animals such as dogs, cats, and livestock which have bitten human beings pose no threat of rabies; prophylactic treatment should not be given unless the incident has been attended by very unusual circumstances. 2) After bites by owned but unidentifiable animals or stray animals, no prophylactic treatment should be given unless the incident has been attended by very unusual circumstances. 3) After bites inflicted by rodents, lagomorphs, insectivores, and nonmammalian vertebrates, prophylactic treatment should not be given. 4) After bites inflicted by exotic animals kept as pets, prophylactic treatment should be given only if the animal demonstrates signs compatible with rabies within io days. If the exotic pet has escaped or is unavailable for observation or if the bite was inflicted by a wild animal which escaped, prophylactic treatment is indicated. 5) After all bat bites prophylactic treatment should be given immediately unless laboratory examination of the bat shows it to be free of rabies. Vol. 52, No. 5, June 1976
6 i 6
J. S. MARR AND A. M. BECK
It is anticipated that the new recommendations will markedly reduce the number of antirabies prophylactic treatments. In past years prophylactic treatment was justified, since rabies continued to occur occasionally in terrestrial animals in the city. More recently such treatments continued to be given since guidelines were based on national recommendations. Since New York City is rabies-free, special local recommendations are justified. ACKNOWLEDGMENTS We thank Dr. Pascal J. Imperato and Mr. Jean B. Cropper for their reading of the manuscript, Ms. Florence Giordano for assisting with the tabulation of data, Mr. Chih Hwa for preparing the figures, and Ms. Sally Koch for typing the manuscript. REFERENCES 1. Imperato, P. J., Marr, J. S., and Beck, A.: Changes in rabies control-New York City. Morb. Mort. Weekly Rep. 24:82, 1975. 2. Harris, D., Imperato, P. J., and Oken, B.: Dog bites-An unrecognized epidemic. Bull. N.Y. A cad. Med. 50:9811000, 1974. 3. Asedo, J.: Discussion-Urban rabies control. Proc. Nat. Rabies Symp., May 1966. Atlanta, U.S. Public Health Serv., 1966. 4. Beck, A. M.: The public health implication of urban dogs. Am. J. Public Health 65:1315-18, 1975. 5. Beck, A. M., Loring, H., and Lock-
6.
7.
8. 9.
wood, R.: The ecology of dog bite injury in St. Louis, Missouri. Public Health Rep. 90:262-67, 1975. Abelseth, M. K., director, Laboratory for Veterinary Science, New York State Department of Health. Personal communication. Winkler, W. G.: Rodent rabies in the United States. J. Infect. Dis. 126:56567, 1972. The New York City Health Code: Title IV, Part B, Section 161.01, enacted March 23, 1959. Corey, L. and Hattwick, M. A. W.: Treatment of persons exposed to rabies. J.A.M.A. 232:272-76, 1975.
Bull. N. Y. Acad. Med.
RABIES IN NEW YORK CITY, WITH NEW GUIDELINES FOR PROPHYLAXIS
JOHN S. MARR, M.D., M.P.H. Director, Bureau of Preventable Diseases
ALAN M. BECK, Sc.D. Director, Bureau of Animal Affairs Department of Health, City of New York New York, N.Y.
INCEthe early part of this century the Department of Health of the City of New York has collected a variety of information concerning animal bites and rabies. The data include case reports and statistics of animal bites, rabies in animals, and rabies in man; the numbers of animals examined for rabies; and the number of individuals per year given prophylactic treatment with antirabies immunizations. These data were reviewed recently in order to determine whether the present national recommendations for prophylaxis of rabies should be modified for persons bitten by indigenous animals in New York City. An analysis was made as to the frequency and type of animal bite, the number of documented rabid animals, the number of animal brains routinely examined for rabies, and the number of individuals receiving immunizations against rabies at the Department of Health's immunization clinics -from 1935 to the present. This information was presented to an Expert Advisory Committee on Rabies convened by the Commissioner of Health in September 1974. The committee confirmed the observation of Department of Health officials that terrestrial rabies has ceased to exist within the city of New York and that recommendations for rabies prophylaxis in bitten persons be changed accordingly. A summary of these findings has been published.' RESULTS Animal bites. Since i908 the Department of Health has kept accurate records of the number of animal bites in New York City during each year. These records were recently summarized.2 The number of reported bite episodes has averaged 32,735 per year during the last two Vol. 52, No. 5, June 1976
6o6
J. S. MARR AND A. M. BECK
CASES 40000
35000
30000
25000
J
20000 1960
1965
1975
1970
YEAR
Fig. 1. Reported cases of dog bite in New York City, 1960 to 1975.
Bull. N. Y. Acad. Med.
6 07
RABIES IN NEW YORK CITY YORK
607
CITY
500
400
0
Dogs
a
Other Animals One horse - 1913 Cats - 1913-1948 Bats - 1959-1975
300
w
200
0 '4
w
0.
ACd
I.[00
I-'
'1
1
[1 H
11
Ii
'4
.0
75
-
50
-
-
25
-
0
I 1. 1" .AX
1910
I
1920
I
I
I
1930
I
I
I
_
1 1940 YEAR
* X A-L
I bd rr l
1950
r--
I 1960
1
_l-
1970
Fig. 2. Number of rabid animals reported in New York City, 1908 to 1975.
decades. The majority of these bites have been from dogs, and the number of dog bites has remained relatively stable in the last five years (Figure i). Rabies in animals. The history of rabies in animals in New York City was summarized by Asedo in I 966.3 He noted that the last case of rabies to be found in a terrestrial animal indigenous to the city occurred in 1954. Since i966 no new rabid terrestrial animals have been Vol. 52, No. 5, June 1976
60o8
15
.
14
-
l-In|ZSz-*Heb|*=w J. S.
13 -
MARR AND A. M. BECK BECK MARR
AND
A.
M.
Case acquired in the City
12
-
11
-
10
-
Case acquired out of town
9sP% 8
-
7
-
'4
a 0
a 6-
5432I-
I,IIIII a
0 --
TI
1905 1910
I
I
1915
I
4I
tihl
I.
SoI III
I
II
I
I
I
1920
1925
1930
.I
1935
1940
I
I
I
I
I,
I
1945
1950
1955
1960
1965
1970
YEAR
Fig. 3. Reported
cases
of human rabies in New York City, 1905 to 1970.
identified within the city, although nine rabid bats have been reported in the city since I959 (Figure 2). Human rabies. Since I905 a total of 98 cases of human rabies has been reported in New York City. Eighty-nine of these were acquired from animals within the city, and the remaining nine resulted from animal bites incurred outside the city. The last case of human rabies acquired from the bite of an indigenous city animal occurred in I944. Bull. N. Y. Acad. Med.
609
RABIES IN NEW YORK CITY
800
-
700
-
600
-
4
A
500-
a
0
.44
21 400
-
'.4
*
Af
One Positive Bat
-
NYC
+ One Positive Animal - Outside
of NYC
300
*
m
*
*
*
*
*
-
*
I-
200 -
100 -
*
+I
+
+
*
*
+
+
*
* *
*
+
*
I
0
1959
1961
1963
1965
1967
1969
1971
1973
1975
YEAR
Fig. 4. Animal brains examined for rabies in New York City (NYC), 1959 to 1975.
Vol. 52, No. 5, June 1976
6 io
J. S. MARR AND A. M. BECK
3500
3000
2500-
2000
15000-
100
1500
1935
1940
1945
1950
1955
1960
1965
1970
1975
YEAR
Fig. 5. Persons receiving antirabies prophylactic treatment in New York City, 1935 to 1975.
The last instance of human rabies resulting from a bite occurring outside the city was in I967 (Figure 3). Examnation of animals for rabies. Since 1959 an average of 634 animal brains has been examined yearly for rabies virus. With the exception of the rabid bats mentioned above and the brains of nonurban animals, there have been no positive brain preparations in city animals during this period (Figure 4). In the same period a total of 250,000 animals has been examined by city veterinarians for clinical signs compatible with rabies; no positive findings resulted. Bull. N. Y. Acad. Med.
RABIES IN NEW YORK CITY
RABIES
6I I
6i
i
Antirabies treatments. The number of persons receiving antirabies prophylactic treatment in New York City has been recorded regularly since I935. The number of persons receiving antirabies prophylaxis has averaged 437 per year during the past to years (Figure 5). DISCUSSION Records of the number of animal bites have demonstrated a large number of incidents in each year (Figure i). The fact that only a fraction of bite victims receive antirabies immunization is indirect evidence of the absence of the disease in animals indigenous to the city. Direct evidence of the absence of rabies virus in city animals is provided by specific brain examinations in animals destroyed by shelters and forwarded to the Department of Health's Bureau of Laboratories for routine examination. The reliability and sensitivity of the testing procedure, which employs fluorescent antibody techniques, has been substantiated by the occasional positive finding in the brains of bats and extra-urban animals (Figure 4). In New York City, as in the rest of the country, the animal responsible for most bites is the dog. This problem appears to be increasing.2' "4'5 Most of the dogs identified as biters within the city are owned animals. In 1975 almost 33,ooo dog bites were reported; 62% were contracted from dogs that were owned and observable. Approximately i9% of the remaining dogs were owned but were not observable because of noncompliance with the procedure of reporting or because of denied ownership. The remaining i9% of bites were from dogs which did not have an identified owner or were ownerless strays. Most owned dogs either are born within the city or are acquired as puppies from pet shops or kennels where vaccination against rabies is a common practice. These owned dogs are not exposed to potentially rabid animals within the city or in kennels which may be outside the city. The likelihood of an owned dog acquiring rabies is small. Although there are an estimated 200,000 stray dogs in New York City, most of these animals were owned at one time or were bred by other dogs within the city. Stray and loose domestic animals have little contact with the few wild animals resident within the city. In addition, the city is virtually isolated from the continental land mass, Bronx County being the city's only land connection. During the past IO years there have been no documented cases of animal rabies within ioo miles of Vol. 52, No. 5, June 1976
6I2
J.
J.
MARR AND AND A. M. BECK S. MARR S.
the upstate counties which are contiguous with the city or within 50 miles of the city in the states which are separated from the city by bodies of water. Ongoing surveillance for the presence of rabies in local animal populations of adjoining states is reviewed quarterly. It would appear from these facts that the city of New York and surrounding territories are free of terrestrial rabies. Importation of the disease by migratory animals is improbable; if it occurred, it would be detected early. In a later paragraph we suggest that recommendations for bite victims be changed accordingly. Although more than 3,000 rabid dogs have been reported in New York City since i908, there have been only 52 confirmed rabid cats and one rabid horse (Figure 2). The last rabid cat was discovered in the borough of Richmond in 1948. The rabid horse was reported in Manhattan in 1913. The peak years for rabies in cats (1913, I926-i930, 1938-i940) were also times in which the rabid dog populations had increased, hence the feline rabies probably represented a result of infections from dogs. With the disappearance of rabies in the canine population, the likelihood of rabies occurring in either the feline or small livestock populations within the city appears to be small. Bites from such animals are now being treated by the methods used for dog bites. Rabies has never been recorded in any rodents, lagomorphs, or insectivores within the city. Although a tiny percentage of rodents in the western portions of the United States may harbor rabies virus, these animals are not considered a source of infection in any part of the eastern United States.7 Our recommendations reflect this. Judging from reports of bites, there are many unusual, wild, or exotic pet animals in the city of New York. Many of these animals belong to public and private zoos which allow human and animal contact. Others are owned by private citizens, legally or illegally. The New York City Health Code proscribes ownership of "an animal of species which is wild, ferocious, fierce, dangerous or naturally inclined to do harm."8 Nevertheless, it is apparent through yearly reviews of bites by exotic animals that man's desire to own unusual animals is limited only by the number of genera available for purchase. In I974 there were i i I bites by wild or exotic animals. Most of these were from monkeys. Since the efficacy of rabies vaccine in animals other than dogs, cats, and livestock is questionable, and since the origin of many owned exotic mammals is often unknown, animals within this category should be Bull. N. Y. Acad. Med.
RABIES IN NEW YORK CITY
RABIES
IN
NEW
YORK
6I3
6i
3
observed closely for Io days for signs compatible with rabies. If signs of the disease develop or brain examination is positive, antirabies prophylaxis should be instituted immediately. If the biting animal escapes or is not available for observation, the treatment should begin as soon as possible. It should be recalled that in the entire experience of the Department of Health's records of rabid animals, -there have never been reports of rabies in animals other than dogs, cats, bats, and one horse. Since I959, when the Department of Health initiated brain examination of all captured bats, only nine bats were found to be positive out of a total of 689 examined (Figure 2). All positive findings in bats were made in late July through early September, and mostly in migratory species, e.g., Lasiurus borealis and L. cinereus. Even with this low frequency, all bat bites should be treated immediately unless the animal is captured and is shown to be free of rabies by fluorescent antibody examination within 24 hours. In cases in which the bat has escaped, prophylactic treatment should be given immediately. The fear of rabies usually has created anxiety in persons bitten by almost any animal. On many occasions laymen and physicians have queried the Department of Health as to the presence of rabies in nonmammalian vertebrates, such as birds, reptiles, and fish. There is no evidence that rabies has ever been contracted from the bite of a nonmammalian animal. Therefore, we do not recommend prophylactic treatment for their bites nor do we examine any of these animals for rabies. As a result of the above analyses, the Department of Health has developed specific guidelines for the management of bites incurred from indigenous animals. These guidelines have recently been issued to physicians in the rabies clinic of the Department of Health. In the past these physicians have used their knowledge of the incidence of the disease in urban animals in counseling bitten persons as to the need for prophylactic treatment. However, since the Department of Health's former guidelines were based on national guidelines, many patients continued to receive prophylaxis. This is evident from an analysis of the records of treatment given in I975. In the first six months of the year I92 persons received prophylactic treatment. In early July 1975 a joint directive from the Bureau of Preventable Diseases and the Bureau of Animal Affairs informed clinic physicians that patients bitten by domestic terrestrial animals within the city need not receive antirabies prophylaxis. In the second six months of 1975 the number of persons Vol. 52, No. 5, June 1976
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J. S. MARR
AND A. M. BECK
TABLE I. GUIDELINES FOR PROPHYLAXIS OF RABIES IN NEW YORK CITY
Animal
Special Prophylactic recommendation considerations
1) Dog, cat, livestock,
rodent, lagomorph, rp insectivore a) Owned b) Unowned or escaped 2) Wild or exotic mammal a) Owned b) Unowned or escaped 3) Bats 4) Nonmammalian vertebrate
None None
Note 1 Note 2
None Treat Treat None
Note 1 Note 3 Note 3 None
Note 1-Unless the animal has arrived recently from an area in which rabies is endemic or the animal demonstrates behavior compatible with rabies within 10 days after the bite. Note 2-Unless the animal clearly demonstrated behavior compatible with rabies at the time of the bite. Note 3-If the animal was captured, prophylactic treatment can await the results of brain examination but prophylaxis should not be postponed more than 24 hours after the bite.
receiving it totalled only i8, although in past years a greater number would have been expected in the second half of the year. Of the i8 persons who received prophylaxis, nine had been bitten by animals outside the city or country. National guidelines were followed in these cases.9 The remaining persons received prophylaxis as a result of unusual circumstances accompanying the bite or through failure of clinic physicians to follow the new guidelines of the city. Probably no more than a few dozen bitten persons will really need antirabies prophylaxis in any future year. These will be persons bitten by bats or other exotic animals within the city or bitten by animals outside the city or country. The new recommendations for antirabies prophylaxis of bitten persons are outlined below (Table I). A schedule also is presented which is similar to that recommended by the Center for Disease Control (Table II).9 SUMMARY AND RECOMMENDATIONS A review of records of animal rabies and human rabies in New York City has revealed an absence of this disease in terrestrial animals for more than 20 years. Ongoing surveillance of captured and killed aniBull. N. Y. Acad. Med.
RABIES IN NEW YORK CITY
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TABLE II. SCHEDULE OF PROPHYLACTIC TREATMENT Day 1 1) Human rabies immune globulin 20 I.U./kg. of body weight intramuscularly (ideally, 1/2 dose should be injected in and around the site of the bite) 2) Duck embryo vaccine-first dose subcutaneously in arm, leg, buttock, or abdomen
Days 2 to Duck Day 31 Duck Day 41 Duck
21 embryo vaccine-first booster subcutaneously, rotating injection sites
embryo vaccine-first booster subcutaneously
embryo vaccine-second booster subcutaneously
mals has shown that the bat is the only continuing source of the infection within the city, although the potential of imported rabies among exotic animals kept as pets has been recognized. Antirabies prophylaxis after dog and cat bites may have been necessary in previous years. However, with the disappearance of the disease in terrestrial animals within the city new recommendations are needed. These recommendations have been based on careful analysis of the history of rabies in New York City and are summarized below: i) Owned, domesticated city animals such as dogs, cats, and livestock which have bitten human beings pose no threat of rabies; prophylactic treatment should not be given unless the incident has been attended by very unusual circumstances. 2) After bites by owned but unidentifiable animals or stray animals, no prophylactic treatment should be given unless the incident has been attended by very unusual circumstances. 3) After bites inflicted by rodents, lagomorphs, insectivores, and nonmammalian vertebrates, prophylactic treatment should not be given. 4) After bites inflicted by exotic animals kept as pets, prophylactic treatment should be given only if the animal demonstrates signs compatible with rabies within io days. If the exotic pet has escaped or is unavailable for observation or if the bite was inflicted by a wild animal which escaped, prophylactic treatment is indicated. 5) After all bat bites prophylactic treatment should be given immediately unless laboratory examination of the bat shows it to be free of rabies. Vol. 52, No. 5, June 1976
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J. S. MARR AND A. M. BECK
It is anticipated that the new recommendations will markedly reduce the number of antirabies prophylactic treatments. In past years prophylactic treatment was justified, since rabies continued to occur occasionally in terrestrial animals in the city. More recently such treatments continued to be given since guidelines were based on national recommendations. Since New York City is rabies-free, special local recommendations are justified. ACKNOWLEDGMENTS We thank Dr. Pascal J. Imperato and Mr. Jean B. Cropper for their reading of the manuscript, Ms. Florence Giordano for assisting with the tabulation of data, Mr. Chih Hwa for preparing the figures, and Ms. Sally Koch for typing the manuscript. REFERENCES 1. Imperato, P. J., Marr, J. S., and Beck, A.: Changes in rabies control-New York City. Morb. Mort. Weekly Rep. 24:82, 1975. 2. Harris, D., Imperato, P. J., and Oken, B.: Dog bites-An unrecognized epidemic. Bull. N.Y. A cad. Med. 50:9811000, 1974. 3. Asedo, J.: Discussion-Urban rabies control. Proc. Nat. Rabies Symp., May 1966. Atlanta, U.S. Public Health Serv., 1966. 4. Beck, A. M.: The public health implication of urban dogs. Am. J. Public Health 65:1315-18, 1975. 5. Beck, A. M., Loring, H., and Lock-
6.
7.
8. 9.
wood, R.: The ecology of dog bite injury in St. Louis, Missouri. Public Health Rep. 90:262-67, 1975. Abelseth, M. K., director, Laboratory for Veterinary Science, New York State Department of Health. Personal communication. Winkler, W. G.: Rodent rabies in the United States. J. Infect. Dis. 126:56567, 1972. The New York City Health Code: Title IV, Part B, Section 161.01, enacted March 23, 1959. Corey, L. and Hattwick, M. A. W.: Treatment of persons exposed to rabies. J.A.M.A. 232:272-76, 1975.
Bull. N. Y. Acad. Med.
