Last week we defined rabies, and discussed the death of the 8-year-old son of the Gambian President – Habibu Adama who died of a dog-bite. Let us now discuss the clinical features, diagnosis and treatment and prevention of rabies.
What are the clinical features of rabies?
- a) Incubation period – 10 days to one year. The closer the dog bite is to the brain the earlier symptoms occur.
- b) Early symptoms of rabies include – systemic infection : fever, respiratory distress and gut disorders like diarrhoea or constipation.
- c) Local symptoms at the bite-site; pain, numbness, redness and generalised swelling, sore throat, difficulty in swallowing and pharyngeal spasms.
- d) Paralysis starts from the lower legs, then moves up through the spinal cord. There could be a short period of mental depression.
- e) There could also be neuropsychiatric disease, acute encephalitis or an upper respiratory tract infection.
- f) Speech is altered and there is profuse salivation. Patient is terrified, in agony, and may be hallucinated or maniacal.
- g) An attempt to drink water, can induce spasm of the throat – thus a person with rabies can’t drink water – hydrophobia.
- h) A patient with rabies eventually develops fits, becomes unconscious and dies within few days.
How do we diagnose rabies?
1) This is more difficult, than is commonly described. Often the child has forgotten his encounter with a dog, and because of long incubation period of rabies, the wound has healed.
2) Rabies is often misdiagnosed as psychiatric disease, upper respiratory tract infection or other mental illnesses, because everyone has forgotten the dog-bite.
3) One method is confinement and observation of the dog for 10 days. If the dog remains healthy after 10 days, then it has no rabies.
4) Cerebrospinal fluid – may help in diagnosis. Or demonstration of the virus by corneal impression smears, or spinning of concentrated saliva.
5) After death it is usually necessary to do post mortem to confirm the cause of death so as to vaccinate family members left behind.
How do we treat rabies?
1) People bitten by rabid dogs rarely develop rabies if appropriate preventive measures are taken, a) Bite area is immediately and vigorously washed with water and soap. b) Deep puncture bites are also flushed with soap water, and the surrounding area properly irrigated.
2) The principles of treatment are to relieve painful spasms and anxiety – barbiturates and chlorpromazine are effective, unfortunately patients usually die after 3 or 4 days. Patients put in ultra-intensive-care-units are known to survive.
3) Medical attendants and relatives must be protected from saliva and other and secretions by wearing masks, goggles, gowns and gloves. Patients should be barrier-nursed. All contaminated materials should be burned or treated with chlorine solution(bleaching powder).
Prevention of rabies.
The prognosis of rabies infection in man is so appalling and frightening, that every community must attempt to eliminate the animal reservoir and to give effective protection to those particularly at risk, and to those who have been bitten by dogs.
What are the general control measures of rabies.
1) Educate the population, including small children about rabies.
2) Reduce the urban animal reservoir by killing stray dogs and cats, encourage reduction in numbers of domestic animals, enforce vaccination of dogs, cats and cattle(a single yearly injection of live-attended virus is used). And discourage dog owners from allowing their dogs to roam around. For mass vaccination to be effective, at least 70% of the total dog population must be vaccinated.
3) Reduce the rural and sylvatic animal reservoir by keeping down the numbers of important species, such as hyanas , especially in the Northern part of Nigeria, where they are known as “kura”, and used in circuit exhibitions. The hyanas should be reduced to below those required to sustain the epizootic. Discourage people from keeping reservoir species as pets, such as meercats in South Africa, and kura in Northern Nigeria.
4) Prevent infected animals from being imported, if possible, by insisting on vaccination and quarantine.
5) Government is through this medium, being asked to improve diagnostic services for human and animal tissue so that the local problem can be fully appreciated.
6) All parents, guardians, uncles and aunts must educate their children aged 5 to 15 years, to report immediately, any encounter with dogs, no matter how minor, for immediate preventive and remedial treatment.
7) People at particular risk from rabies, such as veterinary workers and dog-catchers, can be protected by vaccination. The only vaccine safe enough to be used in this is “duck-embryo-vaccine. The quickest recommended course is three-weekly-injections.
Always be medically guided.
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