Rabies – prevention is safer, cheaper

Dogs and cats are the leading cause of rabies around the world.

Rabies is a viral disease transmitted trough saliva that causes acute encephalitis, or inflammation of the brain. It is almost always fatal if appropriate treatment is not provided in time.

Once the symptoms appear, the disease will always lead to death, in spite of intensive care, sedation and assisted respiration.

The disease kills 31,000 people every year in Asia, and Vietnam has the second highest rate of fatalities after Thailand. In Vietnam, 197 registered people died from rabies, but it is possible that more people were infected and wrongly diagnosed.

It is transmitted by many infected animals through bites, scratches, or even licks on broken skin. Most animals can be infected by the virus, particularly dogs, cats, bats, monkeys, cattle, farm animals and other wild carnivores. Dogs are the source of 95 percent of human rabies infections.

The virus is present in the nerves, brains and saliva of infected animals. After a bite or a scratch, the virus enters the peripheral nervous system and reaches the central nervous system. Vaccination at this stage – when it is in the peripheral nervous system and has not reached the brain yet – can still prevent rabies. Once the virus reaches the brain, it causes encephalitis and it is too late to prevent the disease.

In Vietnam, dogs remain the principal host, but other animals can also be dangerous.

When an animal is infected, it remains asymptomatic for a few days. Then, for four days, it becomes hyper reactive to external stimuli and might bite without apparent cause. Later, it becomes incoordinate, drools, experiences paralysis and will die after respiratory arrest due to paralysis of respiratory muscles.

Symptoms

Early symptoms of rabies are non-specific: fever, headache, weakness or discomfort, in short, flu-like symptoms. Then, the patient may experience anxiety, confusion, agitation, insomnia, paralysis, incontrollable excitement, hyper salivation and hydrophobia (fear of water): despite great thirst, the patient cannot swallow water because of paralysis of jaws and throat. Then the patient begins to go into convulsions, enters a coma and death occurs a few days after onset of symptoms, due to the paralysis of respiratory muscles.

The incubation period for the disease might be as short as two weeks – for wounds close to the head, and as long as two years – for mild wounds like scratches. The shorter the distance between the wound and the central nervous system, the shorter the incubation period.

There are two kinds of symptoms: furious rabies exhibits signs of hyperactivity, excitement and hydrophobia; while paralytic rabies (30 percent of human cases) runs a longer course. Muscles become gradually paralyzed, starting at the site of the wound and the patient slips slowly into a coma. One in every five people who have rabies experiences this rising paralysis.

Diagnosis

No test is available to diagnose rabies infection at the stage when treatment might be efficient. The blood test will only help in diagnosing the condition once serious symptoms have set in. The diagnosis is made by performing a PCR (polymerase chain reaction), which is a modern genetic analysis, or viral culture of the brain after death.

Analysis can also be performed from saliva, urine or cerebrospinal fluid samples.

Other virus might mimic rabies, including the herpes virus, enterovirus, arbovirus and the varicella-zooster virus. These are diseases not related to rabies, but they might mimic rabies. So doctors might perform other tests (serology), to make sure it is not one of those pathologies.

Quarantine

If a non-vaccinated animal bites a human, it must be isolated in a vet’s clinic for ten days and observed by a licensed vet periodically.

In case of a bite, scratch or lick on broken skin, wash the wound carefully with water and soap for at least fifteen minutes. Then apply alcohol solution or iodine solution to the wound. See your pediatrician as soon as possible for advice about antitetanus boosters and antibiotics. Post-exposure immunization will have to be performed if: the patient has not been vaccinated against rabies; has not completed the vaccination protocol; or is older than five years.

The patient will need to be given five shots: day 0, day 3, day 7, day 14 and day 28. For some serious wounds, immunoglobulines might be needed. Immunoglobuline is a passive protection: you provide the patient with antibodies that were synthesized by somebody else. It is very expensive and sometimes dangerous, but might be needed in case the patient does not have pre-exposure immunization.

The most dangerous areas are the face, the head and the neck as they are very close to central nervous system. There is no contraindication to post-exposure immunization.

Prevention

The best prevention is pre-exposure immunization: you need 3 shots at day 0 (first day of the injection), day 7 and day 8, a booster at one year and every five years. The immunization process is best started when the child might be at risk with animals, usually when she/he begins to walk.

The adverse effects are very benign, sometimes erythema, oedema or fever. The shot is no more painful than other vaccines. You can use it during lactation, and the contraindications to pre-exposure vaccine are very few: acute fever or infection, allergy to streptomycine, polymyxine, or neomycine.

Why should you prefer pre-exposure immunization than post-exposure? Because it is more secure, simpler and less expensive. You will be less stressed when travelling in remote areas.

The disease always leads to death, and considering the high prevalence of rabies amongst animals in Vietnam, everybody should be protected.

You need also to teach children not to play with unknown animals. They should not run towards unknown animals. Remember their hands and face are very close to animals and they are more at risk than adults.

Remember too, to consult your pediatrician so that they can help keep your children in good health.

By Dr. Stella Bookaul