Tuesday, October 09, 2007 When rabies attack! By Henrylito D. Tacio Health 101
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. Mary Miranda, leader of the rabies research program at the Research Institute for Tropical Medicine, "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 World Health Organization (WHO), which said that that up to 60 per cent of rabies cases occur in people under 15 years of age.
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 10 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.
