Treating Rabies: An Introduction
There is no treatment for rabies that can cure the disease once symptoms appear. Any treatment at that point involves managing symptoms and making the person comfortable (this is called supportive care). Death is almost certain once the rabies symptoms begin.
However, two decades ago, research scientists developed an extremely effective new rabies treatment regimen that provides protection from the disease when administered after an exposure (post-exposure prophylaxis). The treatment can also be used for protection before an exposure occurs (pre-exposure prophylaxis).
Post-Exposure Rabies Treatment
If a person is bitten by an animal, one of the most effective methods to decrease the chances for infection involves thoroughly washing the wound and scratches with soap and water.
In the United States, post-exposure treatment for rabies consists of a regimen of one dose of rabies immune globulin and five doses of the rabies vaccine over a 28-day period. Doctors administer the rabies immune globulin and the first dose of the vaccine as soon as possible after exposure. Normally, additional doses of rabies vaccine follow on days 3, 7, 14, and 28 after the first vaccination.
Rabies immune globulin contains antibodies from blood donors who were given rabies vaccine. The antibodies provide interim protection until an exposed person's own antibodies develop in response to the vaccine. In addition, injecting rabies immune globulin at the site of injury reduces the amount of virus that is able to enter the nerve cells and potentially initiate an active infection.
The rabies vaccine works by stimulating a person's immune system to produce antibodies that neutralize the virus. The person develops a protective immune response before the virus reaches the brain and begins to actively replicate.
Older rabies vaccines required painful, daily injections in the abdomen (stomach) for up to three weeks, and they could produce severe side effects. Current vaccines are relatively painless and are given in your arm, like a flu or tetanus vaccine.
Beginning post-exposure rabies treatment is a medical urgency, not a medical emergency. Physicians should evaluate each possible exposure to rabies and, as necessary, consult with local or state public health officials regarding the need for rabies prophylaxis.
Pre-Exposure Rabies Treatment
Healthcare providers often recommend pre-exposure treatment for rabies for
people in high-risk groups. These groups include:
• Veterinarians, animal handlers, and certain laboratory workers
• Other people whose activities bring them into frequent contact with the rabies virus or potentially rabid bats, raccoons, skunks, cats, dogs, or other species at risk of having rabies
• International travelers likely to come in contact with animals in areas of enzootic (affecting animals in a specific geographic area) dog rabies, which lack immediate access to appropriate medical care.
People who work with live rabies virus in research laboratories or vaccine production facilities are at the highest risk of unapparent exposures. Such people should have a serum (blood) sample tested for antibody every six months and receive a booster vaccine when necessary. In most circumstances, doctors do not recommend routine pre-exposure prophylaxis with the rabies vaccine.
Pre-exposure rabies treatment consists of three doses of the rabies vaccine given on days 0, 7, and 21 or 28.
Prognosis for Rabies with TreatmentNo one in the United States has developed rabies when the post-exposure treatment regimen discussed in this article was followed. Therefore, as long as treatment for rabies is begun prior to the appearance of symptoms, the prognosis is excellent. When treatment is started after rabies symptoms begin, the prognosis is poor. Death is almost certain to occur within one to two weeks.
Rabies in Animals: An Overview
Although all species of mammals can become infected with the rabies virus, only a few species are best able to spread the virus to other mammals. The animals that most commonly transmit rabies to other animals include:
- Raccoons Skunks
Wild Animals with RabiesWild animals accounted for 93 percent of reported cases of rabies in 2001. The wild animals in which infection was reported included:
- Raccoons -- 37.2 percent of all animal cases during 2001
- Skunks -- 30.7 percent
- Bats -- 17.2 percent
- Foxes -- 5.9 percent
Other wild animals, including rodents and lagomorphs (e.g., rabbits and
hares) -- 0.7 percent.
Outbreaks of infections in terrestrial mammals, such as raccoons, skunks, foxes, and coyotes, are found in broad geographic regions across the United States.
Small rodents (such as squirrels, rats, mice, hamsters, guinea pigs, gerbils, and chipmunks) and lagomorphs (such as rabbits and hares) are almost never found to be infected with rabies and have not been known to cause rabies among humans in the United States. Bites by these animals are usually not considered a risk of infection, unless the animal was sick or behaving in any unusual manner and rabies is widespread in your area.
However, from 1985 through 1994, woodchucks accounted for 86 percent of the 368 cases of rabies among rodents reported to the Centers for Disease Control and Prevention (CDC). Woodchucks or groundhogs (Marmota monax) are often the only rodents that may be frequently submitted to state health departments because of a suspicion of rabies.
In all cases involving rodents, the state or local health department should be consulted before a decision is made to begin rabies treatment.
Rabies Transmission: An Introduction
Rabies transmission can occur in one of a few ways, including: 1) Bites 2)
Non-bite exposure 3) Human-to-human transmission.
A bite from a rabid animal (an animal infected with the rabies virus) is the most common form of rabies transmission. Non-bite exposure and human-to-human exposure are both rare.
Rabies Transmission From Bites
Rabies transmission usually begins when infected saliva of an animal is passed to an uninfected animal, through a bite. From the saliva's point of entry, the rabies virus travels along nerve cells to the brain. It multiplies there and moves to the salivary glands. In a rabid animal, the cycle is repeated when the animal bites a person or another animal.
Rabies Transmission Through Non-Bite Exposure
Rabies transmission from non-bite exposures is rare. Scratches, abrasions,
open wounds, or mucous membranes contaminated with saliva or other
potentially infectious material (such as brain tissue) from a rabid animal,
constitute non-bite exposures. Occasionally reports of non-bite exposure are
such that post-exposure prophylaxis is given.
Inhalation of aerosolized rabies virus is also a potential non-bite route of exposure, but with the exception of laboratory workers, most people are unlikely to encounter an aerosol version of the rabies virus.
Other contact, such as petting a rabid animal, or contact with the blood, urine, or feces (e.g., guano) of a rabid animal, does not constitute an exposure and is not an indication for prophylaxis.
Human-to-Human Rabies Transmission
Rabies transmission between humans is also extremely rare. The only
well-documented cases of rabies caused by human-to-human transmission
occurred among eight recipients of transplanted corneas, and recently among
three recipients of solid organs. Guidelines for acceptance of suitable
cornea and organ donations, as well as the rarity of human rabies in the
United States, have reduced the risk of rabies transmission occurring
through transplanted organs.
In addition to rabies transmission from cornea and organ transplants, bite and non-bite exposures inflicted by infected humans could theoretically transmit rabies, but no such cases have been documented.
Rabies transmission cannot occur through casual contact, such as touching a person with rabies or contact with non-infectious fluid or tissue (e.g., urine, blood, or faeces). In addition, contact with someone who is receiving the rabies vaccination does not constitute rabies exposure and does not require post-exposure prophylaxis.
Rabies in India
Rozario Menezes, MD
Chief Medical Officer (retired), Mormugao Port Authority; Consultant, Pediatrics, Dr. M.M. Mesquita Hospital, Vasco-da-Gama, India
This article has been cited by other articles in PMC.
Rabies is one of the oldest recognized diseases affecting humans and one of the most important zoonotic diseases in India. It has been recognized in India since the Vedic period (1500–500 BC) and is described in the ancient Indian scripture Atharvaveda, wherein Yama, the mythical God of Death, has been depicted as attended by 2 dogs as his constant companions, the emissaries of death.1 Rabies is endemic in India, a vast country with a population exceeding 1.02 billion and a land area of 3.2 million km2.2 Rabies is primarily a disease of terrestrial and airborne mammals, including dogs, wolves, foxes, coyotes, jackals, cats, bobcats, lions, mongooses, skunks, badgers, bats, monkeys and humans. The dog has been, and still is, the main reservoir of rabies in India.3 Other animals, such as monkeys, jackals, horses, cattle and rodents, seem to bite incidentally on provocation, and the fear of rabies leads the victim to seek postexposure prophylaxis. The number of cases involving monkey bites has been increasing in the last few years. Monkeys are susceptible to rabies, and their bites necessitate postexposure prophylaxis.
Incidence of human rabies
Human rabies has been eradicated in some developed countries, but it is still present in many others, including those in Southeast Asia (Figure 1).4
Figure 1: Presence and absence of rabies worldwide, 2006.4 Reproduced with permission from the World Health Organization.
In India, about 15 million people are bitten by animals, mostly dogs, every year and need postexposure prophylaxis. Since 1985, India has reported an estimated 25 000–30 000 human deaths from rabies annually (the lower estimate is based on projected statistics from isolation hospitals in 1985).2 The majority of people who die of rabies are people of poor or low-income socioeconomic status.3 The incidence of death from rabies in Asia is given in Figure 2.5 Because rabies is not a notifiable disease in India and there is no organized surveillance system of human or animal cases, the actual number of deaths may be much higher. The latest figure projected from the National Multicentric Rabies Survey, conducted in 2004 by the Association for Prevention and Control of Rabies in India in collaboration with the World Health Organization,1 is 20 565 deaths from rabies per year.
Figure 2: Incidence of human deaths from rabies in Asia, 2004.5 Reproduced with permission from the World Health Organization.
Most animal bites in India (91.5%) are by dogs, of which about 60% are strays and 40% pets. The incidence of animal bites is 17.4 per 1000 population. A person is bitten every 2 seconds, and someone dies from rabies every 30 minutes. The annual number of person-days lost because of animal bites is 38 million, and the cost of post-bite treatment is about $25 million.2 The steady increase in the number of cases involving dog bites and an ever-increasing demand for postexposure vaccination poses the question of whether India is in the midst of an epidemic of rabies in dogs or whether these increases merely reflect uncontrolled growth in the dog population and greater number of humans exposed to them.
Management of stray dog population
India has approximately 25 million dogs, with an estimated dog:man ratio of
1:36.2 The dogs fall into 4 broad categories: pets (restricted and
supervised); family dogs (partially restricted, wholly dependent); community
dogs (unrestricted, partially dependent); and feral dogs (unrestricted,
independent). Most dogs in India, perhaps 80%, would fall into the last 3
Until 1998 the population of stray dogs in India was kept under check by civic authorities, by impounding and euthanizing unclaimed dogs. Because of pressure from animal welfare activists, this approach was replaced by a policy of animal birth control, also referred to as the ABC Programme. In this program, stray dogs are impounded, surgically sterilized and released back into the area from where they were picked up. The success of this program hinges on the sterilization of 70% of the strays in a given geographic area within 6 months, before the next reproductive cycle begins, otherwise the entire effort is negated. This target is difficult to achieve, given the large number of strays and the limited resources. Hence the success of the animal birth control program in controlling the stray dog population is a subject of dispute and doubt.6 Diagnosis of rabies
In most cases, human rabies is diagnosed primarily on the basis of clinical symptoms and signs, and a corroborative history of or evidence of an animal bite, death of an animal, and incomplete or no vaccination following exposure.2 The facility for laboratory diagnosis and confirmation of rabies, be it in humans or in animals, is available premortem in only a few institutions in India. The standard premortem test is a fluorescent antibody test to demonstrate the presence of viral antigen. The standard postmortem test is biopsy of the patient's brain and examination for Negri bodies. Autopsies are rarely performed.
Use of vaccines and immune globulin
Twelve institutions in India were producing the nerve-tissue (Semple) vaccine in quantities necessary for use in humans (40 million mL) and animals (90 million mL) annually until 2003/04. Since then, the use of the nerve-tissue vaccine has been phased out and, as of 2008, replaced by modern tissue-culture vaccine.7 Most people received the vaccine at government and municipal anti-rabies clinics. Each case required a mean of 4.4 visits for treatment, at a cost of at least Can$50 (for the vaccine and other medicines) and a loss of 2.2 days of work.2
In the past, a large proportion of rabies patients did not receive any vaccination, and of those who did, many did not complete the full course. In the latest survey, in 2004, only 39.5% of bite victims washed the wounds with soap and water, and about 46.9% received rabies vaccination. The survey revealed that the use of tissue-culture vaccine was higher than that of nerve-tissue vaccine, and compliance to the full course was about 40.5%. However, the use of human rabies immune globulin was low (2.1%).
The 2004 survey also revealed that about 60% of infected people resort to indigenous treatment, with local applications to the wound (36.8%) and indigenous remedies (45.3%) being popular.2 Realizing that even at the dawn of 21st century thousands of people in India are dying from rabies, some of the medical professional bodies such as the Indian Academy of Pediatrics and the Association for the Prevention and Control of Rabies have taken action. They have collaborated to create awareness, develop strategies suitable to the Indian situation, popularize the use of intradermal vaccination, with a view to reduce the high cost of treatment and cooperate with the government to reduce the incidence of death from rabies, with the ultimate goal of eradicating rabies from the country.
To first reduce then eradicate deaths from rabies, collaborative efforts
will be required from multiple stakeholders, including veterinarians, public
health officials, legal authorities and other health care services (Box 1).
There must be strict implementation of the legal provisions for licensing and regular vaccination of pet dogs. At the same time, dedicated efforts are needed to control the population of stray dogs, through animal birth control programs and mass vaccination, and to eliminate suspected infected animals.
Public health educational programs are needed to create awareness both in the medical community and in the public regarding the dangers of inadequately managed animal bites. The importance of proper wound care, postexposure vaccination with modern tissue-culture vaccine and the administration of human rabies immune globulin, where indicated, must be reinforced.
Modern tissue-culture vaccines, which are currently administered intramuscularly, must be made more widely and easily accessible. Efforts are needed to lower the prohibitive costs of postexposure vaccination by introducing and popularizing the intradermal route of rabies vaccination, which requires just one-tenth of the intramuscular dose. The possibility of adding pre-exposure vaccination to the routine childhood immunization schedule should be considered.
The facilities for the surveillance and diagnosis of animal rabies must be improved in quality and offer wider coverage, and human rabies must be made a mandatory reportable disease. Rozario Menezes MD Chief Medical Officer (retired) Mormugao Port Authority Consultant, Pediatrics Dr. M.M. Mesquita Hospital Vasco-da-Gama, India