Rabies: If bites could kill

by Henrylito D. Tacio

After two of its men contracted rabies from dog bites in the Philippines recently, the Japan’s Health Ministry immediately urges its citizens to stay away from dogs while on trips abroad. Rabies is rare in land of the rising sun, where pet dogs are required to be vaccinated and stray dogs are rounded up by health authorities.

Be careful not to be bitten by dogs,” says the warning posters, which are placed at all international airport quarantine offices in Japan. “Once developed, rabies almost certainly kills you.” The poster shows a map of infected areas around the world and a photograph of a dog bearing its teeth.

While Japan and other Asian countries like Hong Kong, Singapore, and Taiwan are considered rabies-free, the disease is a serious threat elsewhere on the continent. According to the World Health Organization (WHO), rabies claims 400 and 2000 lives in the Philippines and Pakistan respectively each year. But India is hit hardest – rabies kills a staggering 30,000 Indians annually.

Health experts, however, fear the real toll may be much higher. “We believe the death toll could be higher because of the many deaths that go unreported in remote parts of the country,” says Dr. Mary Miranda, leader of the rabies research program at the Research Institute for Tropical Medicine. “In most parts of the region, surveillance of rabies is inadequate and not given priority compared with other infectious diseases like tuberculosis and malaria. Also, there are not too many laboratories doing rabies diagnosis.”

People almost always contract rabies from the saliva of rabid animals. Any warm-blooded animal can be infected, but dogs are by far the commonest source. In the Philippines, dogs are responsible for over 90 percent of rabies deaths. “The usual pattern of transmission is dog to dog,” explains Dr. Miranda, “and then from dog to human.”

Children are at greatest risk, because they’re most likely to play with dogs. This has been confirmed by the United Nations health agency, which said that that up to 60 per cent of rabies cases occur in people under 15 years of age.

Take the case of Edward. The lively eight-year-old was bitten by a puppy dog on his hand while playing with the three-month pet. The parents did not give any significance to the small tooth mark (as a result of the bite) and just cleaned the wound with antiseptic. They forgot the whole incidence and never bothered to consult a doctor even when the puppy died five days after Edward was bitten.

Ten days after the biting incident, the boy developed fever and it was then that the parents brought the child to a doctor who prescribed some medicine. Two more days passed and the boy started talking irrelevantly, looked confused and became sleepless. The next day, he refused to take any water and even food. At this time, the parents brought him back to the hospital where both the mother and father were interrogated. They told the biting incident.

The attending physician suspected rabies and offered the boy a glass of water. Just by looking at the glass of water, the boy went into spasms and looked terrified. “I feel pity staring at the little boy who’s suffering from an incurable malady just because he had played with a puppy,” the doctor lamented.

Though bites are the usual form of transmission, rabies can also be contracted if open wounds or mucous membranes in the eyes, nose and mouth come into contact with saliva from a rabid animal, or if an infected person kisses a partner. In rare cases, victims contract it from inhaling the air-borne virus – in caves inhabited by rabid bats, for example – or by drinking unpasteurized milk from a rabid animal.

But how can you tell if an animal is rabid? “A common clue is a sudden change of behavior, like drooling, unprovoked aggression, biting, aimless running and difficulty breathing,” informs Dr. Silvius Alon, a veterinarian. However, some infected animals may become paralyzed or die suddenly without showing signs of illness.

Dr. Alon shared the story of one of his neighbors. Jose, the owner, noticed his dog named “Bantay” was acting strange. This was three days after a stray dog bit “Bantay.” The once-tame pet has become fierce. The dog attacked anything or anyone that comes its way. Jose put him in a cage and consulted Dr. Alon. Jose told him about the animal’s changed personality. After hearing and by observing the dog’s behavior, the veterinarian diagnosed rabies.

In humans, rabies symptoms can take weeks or months to appear. This presents a real problem when treating the disease because by the time symptoms have developed it may be too late to prevent death. When an infected animal bites a person, the virus travels along the nerves to the central nervous system where it incubates for up to three months. In this period the victim shows no signs of illness.

At the end of the incubation period, the virus multiplies rapidly, spreading to the brain and throughout the body, even to the eyes and extremities like hair follicles. Initial symptoms, in what doctors refer to as the “prodromal stage” of the disease, may be mild. They last from two to ten days and include a slight fever, headache, nausea and persistent loose cough. There may be pain, itching, tingling or a sensation of cold at the bite site.

Then, in the “acute neurological stage,” symptoms become more and more frightening. For the next two to seven days, the patient becomes nervous, agitated, restless and irritable, and may salivate excessively. As the virus replicates in the brain, the victim experiences eye problems (like enlargement of the pupils), weakness of the facial muscles and hoarseness.

In one out of six cases, there’s hydrophobia – a fear of water. “In this stage, there is forceful, painful muscle spasms of the throat, which expel liquids administered orally,” says Dr. S.N. Madhusudana, associate professor of the Department of Neurovirology at the National Institute of Mental Health and Neuroscience in Bangalore, India.

Finally, the virus overwhelms the brain and central nervous system. The patient falls into a coma, becomes paralyzed and dies.

What should you do if you’re bitten by a rabid animal? First, attend to the wound immediately. “Wash it with plenty of soap and running tap water,” instructs Dr. Madhusudana. “Then apply an antiseptic like iodine or betadine to kill the virus.”

As soon as the wound has been cleaned, seek medical help. Victims must be immunized as soon as possible so that antibodies can develop before the virus incubates. Injection must be done into the bite sites to neutralize the virus. “Once the virus reaches the brain, the antibodies are no longer effective,” says Dr. Miranda.

Patients should receive “active” and “passive” immunization, whether the animal turns out to be infected or not. In the active form, a vaccine is injected daily for 14 to 30 days and the patient’s immune system responds by producing antibodies. When the course is finished, booster doses should be given after 10 and 20 days.

In “passive” immunization, rabies immunoglobulin or antiserum should be administered to provide “ready-made” antibodies and another weapon to fight the infection. Antiserum can either be of human (human rabies immunoglobulin – HRIG) or horse (equine rabies immunoglobulin – ERIG) origin.

HRIG, produced from human blood products, is expensive. That’s why ERIG is recommended and used in Asia as a first line of defense. It’s just as safe and effective as the former, but costs a tenth as much.

Serious allergic reactions to the rabies vaccine are rare during the series of five injections. However, doctors some adverse reactions that a person may experience after receiving the vaccine include abdominal pain, itching, muscle aches, dizziness, and inflammation. These adverse reactions, however, can be managed with anti-inflammatory and antipyretic drugs.

If possible, any dog that bites a person should be confined and observed. “If the dog remains healthy for ten to 14 days, it’s safe to assume it’s rabies-free,” says Dr. Miranda. If the animal does show symptoms, the owner should contact the local health department or a vet immediately and the dog should be humanely put down.

Recently, Senator Pia Cayetano filed a bill that seeks to eradicate rabies in the country by 2020. Her bill consolidates several that have been filed by other legislators in the Senate and the House of Representatives aiming to establish a national rabies control program. “It is more than time that we legislate a program that would protect both man’s best friend and the hand that feeds them,” she said in a speech at the Senate.

As in all illnesses, prevention is the best defense. To that end, one of the most effective weapons in areas where the disease is endemic is pre-exposure vaccination, especially for children. “In my country, or in other parts of Asia, where rabies is still a big problem, I highly recommend pre-exposure vaccination, particularly among children living in areas where stray dog menace is rampant,” says Dr. Madhusudana.

The vaccination consists of three low-dose injections over a month. According to medical experts, if you’re bitten by a rabid animal after that, the only treatment you may need is two booster doses of vaccine three days apart.

Vaccinating pets and livestock can help prevent rabies too, says Dr Thavatchai Kamoltham, an expert in preventive medicine in Thailand’s Phetchabun province. In Thailand, which set up an animal-vaccination program, rabies deaths dropped from 400 in 1991 to 70 in 2000, the years when the program was carried out. In Malaysia, mass vaccination and culling the stray dog population has checked the rabies problem. In 1953, the Malaysian government started implementing the program that by April 1954, the country was declared rabies-free.

The public, particularly parents, have a vital role in any educational campaign. “Parents must remind children NEVER to touch or feed stray dogs or cats,” advises Dr Alon. — ###

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