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Dog bites and rabies - II



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By Vidyajyothi Dr. Wijaya Godakumbura


Consultant Surgeon


Continued from yesterday


Around 90% of cases of rabies e are the result of dog bites in countries where dogs commonly have rabies, while in the Americas less than 5% of cases are due to dogs, with bats being responsible for most of the cases. Animal control and vaccination programmes have decreased the risk of rabies from dogs in a number of regions of the world. In Switzerland, the disease has been virtually eradicated after scientists placed chicken heads laced with live attenuated, i.e. deactivated, vaccine in the Swiss Alps. The foxes of Switzerland, proven to be the main source of rabies ate the chicken heads and got immunized !


In many cases, the infected animal is exceptionally aggressive, may attack without provocation, and exhibits, otherwise uncharacteristic behaviour. This is caused by a micro organism modifying the behaviour of its host to facilitate its transmission. Once the patient becomes symptomatic, treatment is almost never effective and mortality is over 99%.


All over the world, 50 million dogs are vaccinated against rabies every year. Some countries such as China, Iran and Thailand have achieved very good results through the vaccination of dogs and humans bitten by animals. In Morocco, Tunisia and Sri Lanka, the disease has been controlled to some extent. There are 2.5 million dogs in Sri Lanka, and 70% of the dogs in Colombo have been sterilized and vaccinated. In some African and Asian countries, only 30-50% of the dogs population has been vaccinated, and this is not sufficient to control the disease.


Dogs have to be vaccinated annually against rabies and certain other diseases. In some countries a microchip is inserted under the skin of pet dogs, which is similar to the SIM card. A few decades ago, stray dogs were exterminated in Sri Lanka to reduce the dog population, but it is not done now. Instead they are now sterilized.


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The rabies virus is present in the saliva of infected animals. When it bites another animal or human, the viruses enter the body of the victim. The chances of contracting the disease depend on certain factors. If it was just an abrasion, or the bite occurred through clothes, the chances of enough viruses entering the body to cause the disease are low. If the wound is deep, or the bites are multiple, the opposite holds. The viruses travel along the nervous system toward the brain, multiply rapidly and start destroying nerve cells. When the brain of an infected animal is examined under a microscope, the viruses are seen packed together in large numbers inside cells like bees in a hive. These are called Negri bodies.


Symptoms in the rabid dog


Three stages of rabies in mammals are recognized. The readers should be familiar with them to suspect when they see a dog which may be rabid and take precautions. The first stage is a one- to three-day period characterized by behavioural changes. It starts to snarl, growl and eat soil, leaves, sand, etc. The second is the excitative stage, which lasts three to four days. This stage is often known as ‘furious rabies’ because the affected animal tends to be hyperactive and bites at anything nearby. The third is the paralytic stage caused by damage to nerve cells. Inco-ordination is seen owing to paralysis of rear limbs. Paralysis of facial and throat muscles cause drooling of saliva and difficulty in swallowing, and death is caused by respiratory arrest.


Symptoms of human rabies


The rabies virus can enter through a bite of a rabid animal, or through the person’s nose, mouth, eye or an old wound in the skin. It takes 25-100 days for the disease to manifest itself. This period is known as the incubation period, and the virus multiplies rapidly during this time and there will be millions in the brain. The period between the date of the bite and the appearance of the symptoms varies according to the distance from the site of entry of the virus to the brain. If bitten on the head or neck, the disease appears in 20-30 days, if on a hand, 40-50 days and if on a leg, 80-90 days.


First, there will be pain in the bitten region, with depression and insomnia. There will be tightness in the throat when drinking is attempted. Due to the paralysis of muscles used in breathing, he will have difficulty in breathing. He panics when given liquids to drink. Even the mere thought or suggestion of drinking may cause painful spasms of the muscles in the throat. He will also develop fever, vomiting and salivation. Later, the whole body will be paralysed and death follows.


For obvious reasons, the chances of getting rabies are greater when the wounds are large, multiple and in upper parts of the body. If the dog has been vaccinated every year for two years, and if it had no chance of mingling with other animals, it cannot carry the virus. Therefore, vaccination is not necessary. However, this decision is to be taken by a doctor, and not the bitten person or a family member. Only very few persons have survived after contracting rabies. A person dies of this disease every 10 minutes in the world, and half of them are children under 15 years of age. In 2011, 43 people died in Sri Lanka.


Quote from the World report on child injury prevention:


"Dog-bite injury is a widespread and hitherto poorly-documented global problem, disproportionately affecting children and adolescents. Good data collection systems are vital for identifying the characteristics of injuries such as dog bites. Only when good data become available can the extent and nature of such injuries be appreciated and proper prevention measures set up". September 28 is World Rabies Day, which promotes information, prevention, and elimination of the disease.


Code of behaviour to prevent dog bites Courtesy World report on child injury prevention


* Dogs sniff as a means of communication.


Before petting a dog, let it sniff you.


* Dogs like to chase moving objects.


Do not run past dogs.


* Dogs run faster than humans.


Do not try to outrun a dog.


* Screaming may incite predatory behaviour.


Remain calm if a dog approaches.


* Dogs may regard infants as intruders or as subordinate when born to a family in to which the dog feels integrated.


Be mindful of this when a new baby arrives.


* Direct eye contact may be interpreted as aggression.


* Avoid direct eye contact.


* Dogs tend to attack extremities, face and neck.


* If attacked, stand still with feet together. Children should protect neck and face with hands.


* Lying on the ground provokes attacks.


Stand up. If attacked while lying, keep face down and cover the ears with the hands. Do not move.


* Fighting dogs bite at anybody that is near.


* Do not try to stop fighting dogs.


* In addition, never annoy them, and never try to take anything from their mouth even if it is something valuable. Do not disturb a dog when it is eating, sleeping or with pups. Avoid talking aloud near dogs or make sudden movements.


After a bite


Wash the wound quickly with soap and flowing water for 10 - 15 minutes. Do not apply anything on the wound. If possible, tie the dog for observation. If it was a stray dog, remember its features for later identification. Go to a doctor without delay, same day if possible, if not next morning. Many people will advise about things to do. Ignore them and do not take ‘medicines’ from people who have no medical qualifications. The Health Ministry spends Rs. 600 million every year to vaccinate people who are bitten by animals. It is tragic that some go to quacks taking a very big risk. If the dog dies, take the head to a government hospital for further examination, but be very careful when you handle it.


Remember. Rabies is a fatal disease. Don’t take any chances when bitten by an animal. If everybody is careful, the disease could be eradicated from our country. (safelam@sltnet.lk).


(Concluded)


 
 
 
 
 
 
 
 
 
 
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