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Indiana State Department of Health

Epidemiology Resource Center Home > Surveillance and Investigation > Surveillance and Investigation Division > Newsletters > Indiana Epidemiology Archived Newsletters > Epi_Newsletter_April_2007-HumanRabies Human Rabies Case in Indiana

Indiana Epidemology Newsletter
April 2007

Jim Howell, DVM
Veterinary Epidemiologist

On November 2, 2006, a 10-year-old girl from Marshall County, Indiana, died from rabies. This is the first known human rabies case in Indiana since 1959, when a Sullivan County boy died from rabies. Historically, human rabies cases have not been so rare. Between 1900 and 1949, there were 120 recorded deaths; and between 1950 and 2006, there were 10 recorded deaths, most of which occurred in the 1950s. Figure 1 shows the distribution of cases by decade. The good news is that the risk of rabies to Hoosiers has greatly decreased over time, however, the risk remains for rabies transmission from reservoir species to both our pets and ourselves.

Bar chart depicting the distribution of rabies cases in Indiana from 1900 to 2006.

The Marshall County girl was bitten by a bat in her home in late June. At the time, the exposure was not considered significant; therefore, she did not receive medical assistance. On September 30, while visiting her father in the Chicago area, she complained about her arm hurting and was given an over-the-counter pain medication. Over the next 5-6 days, she complained of non-specific symptoms and was seen twice by health care providers. By October 7, she was dehydrated and admitted to a local hospital. On October 8, she showed increasing signs of neurological illness and was transferred to an Indianapolis tertiary hospital for additional evaluation and care. During the next week, the history of the bat exposure resurfaced, and biopsy material, saliva, and spinal fluid were submitted to the Centers for Disease Control and Prevention (CDC) for testing. The tests were positive for rabies virus, and the virus was identified as the silver-haired bat strain. In spite of extensive medical care, the child died on November 2.

Rabies has long been an issue for the citizens of Indiana. The Bacteriological Laboratory of the Indiana State Board of Health identified the first laboratory-confirmed rabid animal using Negri bodies as criteria on December 1, 1906. As laboratory methods improved, knowledge of the lab’s capability became widespread, and the logistics of transporting an animal’s head to Indianapolis became easier, the number of animals tested and the number of rabies positives increased. In the late 1950s, the direct fluorescent antibody test became available, and the Indiana State Board of Health Rabies Laboratory adopted this much improved method of testing. Table 1 provides the number of positive specimens examined in the first seven years of laboratory testing.

Table 1. Rabies-positive Animals Identified at the Indiana State Board of Health Laboratory

Year

1907

1908

1909

1910

1911

1912

1913

Number Positive

4

73

69

66

115

166

198

In 1912, testing for rabies in wildlife would not have been a high priority and was overshadowed by the concern for rabies in domestic animals and human exposure from those animals. Humans exposed to rabid animals were treated with the Pasteur treatment, a series of injections of rabbit spinal cord dried for varying lengths of time. In 1911, the Indiana General Assembly adopted rules that required the Indiana State Board of Health to provide the Pasteur treatment free for indigents, and the Indianapolis Pasteur Institute suggested its availability to provide such treatment for $50 per treatment.

Table 2. Test Results for 320 Animals Examined for Rabies at the Indiana State Board of Health Laboratory, 1912

Species

Dog

Cat

Hog

Cow

Horse

Human

Rabbit

Positive

146

1

1

9

1

 

 

Negative

133

1

1

 

1

1

1

Unsatisfactory

6

 

 

 

 

 

 

In 1932, the Indiana State Board of Health Annual Report listed both the number of animal heads found positive for rabies and the number of anti-rabies treatments given to people. This listing illustrates the increasing use of the Board of Health Laboratory and demand for anti-rabies treatments over time. The number of anti-rabies treatments given is a reflection of the number of animals determined to be rabies positive by the Laboratory.

Figure 2: Patients receiving anti-rabies treatment from the Indiana State Board of Health, 1917-1932.

In 1923, the Indiana General Assembly declared that dogs were considered private property and could be taxed as private property. In 1937, the Indiana General Assembly declared that the personal property tax on dogs would go into the township dog fund and be used for payment to individuals for damage to livestock by free roaming dogs or “for the taking of the Pasteur treatment for hydrophobia incurred by any person by reason of a person being bitten by, or exposed to, a dog known to have hydrophobia, within any township of Indiana.”

The 1943 Indiana State Board of Health Annual Report states that 123 individuals received free rabies antitoxin that year. These individuals represented 21 counties, with the number of individuals receiving vaccine ranging from 1 to 30. Counties with the most recipients were Vanderburgh (30), Jackson (25), Greene (16), and Lake (10). This statement only referred to those who received free treatment and did not include those who received treatment at their own expense.

During the 1920s, national efforts to prevent rabies in people transitioned to preventing and eliminating rabies in dogs, the most frequent source of rabies in people. This included leash laws, area-wide quarantines, and the introduction of rabies vaccines for dogs. In 1921, phenolized inactivated virus vaccine was first used to immunize dogs. In 1938, a human rabies isolate was grown in day-old chicks and embryonating chicken eggs to develop an attenuated live virus vaccine for animals. In 1948, the Flurry strain virus was used to develop another day-old chick and embryonating chick egg attenuated live virus animal rabies vaccine. The last two vaccines were majorly responsible for the reduction of canine rabies in this country.

In 1938, rabies in both humans and animals became nationally reportable. There were 9,412 cases that year, with 47 human deaths. It is certain that cases were underreported, as there was limited surveillance and the laboratory testing was not as sensitive as what is used today. Nationally, in 2005, there was a total of 6,419 reported cases of rabies, which included only 494 domestic animal cases and 1 human case. Of the 494 domestic animals, only 76 occurred in dogs. Recently, the CDC announced that the canine rabies virus variant has been eliminated from the United States—a profound success for rabies control programs. Dogs continue to contract rabies, mainly from exposure to wildlife reservoirs, and it is essential that dogs continue to be vaccinated against rabies. Rabies in cats has been more frequently reported for a number of years in part due to the failure to vaccinate cats that have access to the outdoors and to reservoir animals.

Statistics for animals testing positive for rabies in Indiana are available from 1945-2006 and are used for the rest of this article (Table 3).

Table 3. Number of Animals Identified as Rabies Positive by Species, Indiana, 1945-2006

Species

Number

Species

Number

Dogs

5,404

Skunks

908

Cats

468

Bovines

322

Bats

284

Foxes

242

Horses

15

Pigs

4

Raccoons

4

Woodchucks

2

Goats

1

Mouse

1

Opossum

1

Sheep

1

 

 

Other

94

Indiana’s experience with rabies follows the national experience. The number of dogs with rabies markedly decreased after the introduction of the improved rabies vaccine and especially after the introduction of the Flurry strain vaccine in 1948. Rabies vaccination for dogs was first legally required in Indiana in 1958 and for cats in 1994. The impact of leash laws and voluntary vaccination had already made an impact on the number of rabid dogs by that time. Figure 3 illustrates the tremendous drop in the number of rabies cases per year in domestic animals (mostly dogs) in the late 1940s to the early 1960s.

Figure 3: Animal Rabies in Indiana from 1945-2006 as described in the previous paragraph.

Reports of rabies in cattle in Indiana during this time period have increased or decreased in relationship to the number of reported skunks with rabies. Figure 4 illustrates the epidemic of skunk rabies in Indiana from 1960 to 1985. Without knowing the number of skunks being submitted for rabies testing from 1945 to 1960, the positives reported here may represent testing selection in favor of domestic animals in a passive surveillance system. The number of skunks submitted for rabies testing from the 1980s to the present has decreased significantly, with only four skunks submitted in 2005. The relationship between the number of skunks being submitted and the number of positives is shown in Figure 5.

Figure 4: Rabies in selected species in Indiana as described in the previous paragraph.

Figure5: Skunks submitted for rabies testing in Indiana, 1966-2006

Rabies in bats, the source of rabies infection for the 2006 Marshall County human rabies case, was first recognized as a source of rabies for human infection in 1956 when a boy from Florida died after being infected by a bat bite. The state Rabies Laboratory identified the first confirmed rabies positive bat in 1965. Although the number of bats submitted to the Laboratory has increased, the number of bats testing positive for rabies has never exceeded 32 per year and has averaged 7.6 positive bats per year. From 1966 to 2006, 5 percent of the bats submitted for testing have been rabies positive. The percentage of positive bats has ranged from 1.3 percent to 15.3 percent positive, but from 1966-2006, 5.1 percent of the bats submitted have been rabies positive. Counties that have submitted positive bats since 1965 are shown in Figure 6.

Figure 6: Map showing Indana counties with rabid bats from 1965 through 2006

While not every county has submitted a positive bat to the Laboratory, most counties have at some time during this time period. Marshall County, the residence of the 2006 human rabies case, has submitted three positive bats, the last in 1989. All counties should assume that there are rabies-positive bats present. When evaluating individuals who have been exposed to a bat, one should assume the bat is rabies positive until proven negative by the Laboratory. Figure 7 shows the species and the number of cases of rabies in Indiana in 2006.

Figure 7: Map of Indiana couties with rabies cases in 2006.

The Indiana State Department of Health (ISDH) Rabies Laboratory continues to test a large number of animals for rabies and, in 2006, tested almost 1,800. Testing still primarily includes dog and cats, as these species have more contact with humans and bite individuals more frequently than other animals. The ISDH Rabies Laboratory also conducts rabies testing diagnostically for veterinarians to eliminate rabies as a cause of death for animals with a neurological disease. Figure 8 illustrates the range and number of species that are submitted to the Laboratory each year.

Figure 8: Bar chart indicating the species and number tested for rabies in Indiana in 2006

Much has changed during the 100 years since the state Rabies Laboratory starting using the Negri body as a diagnostic test for the presence of rabies—new er and better diagnostic testing; the capability to do molecular testing to determine source of virus; better immune globulin and rabies vaccine to prevent the disease in people; and the change from dog, to skunk, to bat as the primary reservoir of rabies virus in Indiana. While the impact of rabies on people has been greatly reduced due to a number of factors, it is important to appreciate the importance of proper animal bite management as a public health message.

 This article is dedicated to the current and former Indiana State Rabies Laboratory workforce for 100 years of service in handling potentially highly infectious animals to enable important medical decisions to protect the health of Indiana citizens.