Rabies is a deadly but vaccine preventable viral disease of mammals, mostly transmitted from rabid animal’s saliva that enters the body through a bite or broken skin. Rabies virus infects the central nervous system and if untreated, rabies can lead to coma and death.
Rabies causes acute inflammation of the brain in warm-blooded animals. The disease can be transmitted from one species to another, such as from infected dogs to humans of all age groups. For human, rabies is almost invariably fatal if post exposure prophylaxis is not administered prior to the onset of severe symptoms. The rabies virus infects the central nervous system, ultimately causing disease in the brain. Rabies may also inflame the spinal cord, producing transverse myelitis. In many cases, the infected animal is exceptionally aggressive, may attack unprovoked and exhibits uncharacteristic behaviour. Rabies is an example of viral pathogen modifying the behaviour of its host to facilitate its transmission to other hosts. After a typical human infection by bite, the virus travels fast along the neural pathways into the central nervous system and other organs.
The incubation period of the disease is usually a few months in humans, depending on the distance the virus must travel to reach the central nervous system. Once the rabies virus reaches the central nervous system and symptoms begin to show, the infection is virtually untreatable and usually fatal within days. The rabies virus travels to the brain by following the peripheral nerves. Also the salivary glands of the rabid animal harbour high concentrations of the virus, thus promoting further transmission.
Globally rabies causes about 55,000 human deaths (95% in Asia and Africa) annually. Roughly 97% of human rabies cases result from dog bites. Death almost invariably results within 2 to 10 days after first symptoms. Once a patient becomes symptomatic, survival is rare and mortality is over 99%, even with the administration of proper and intensive care.
Rabies is a neglected disease of poor and vulnerable populations whose deaths are rarely reported. It occurs mainly in remote rural communities where measures to prevent dog to human transmission are hardly implemented. Under-reporting of rabies cases also militates against mobilization of resources and intervention programmes from the international community for the elimination of human dog-mediated rabies.
We must interrupt rabies disease progression by partnering in its control and management. This is why this public document is supporting the rabies awareness campaign.
WHAT IS RABIES
Rabies is an acute viral infection that affects the central nervous system of all warm-blooded animals and it is principally transmitted to man through bites from infected dogs. Rabies symptoms appear after an incubation period of 10 days to over a year and death occurs in about 5 days of infection. It is a vaccine preventable viral disease often transmitted to mammal from rabid animal’s saliva that enters the body through a bite or wound. The virus travels from the entry port to the brain where it causes virulent swelling or inflammation. The inflammation provokes the symptoms of the disease which may finally result to death especially in children.
Rabies is known to be present in all continents except Antarctica. It infects domestic and wild animals. Infected animals can spread the virus by biting another animal or human. In rare cases, rabies can be spread when infected saliva gets into the mucous membranes such as the mouth or eyes. Rabies infection is possible if an infected animal licks open wound or cut on the skin including the anus. Although it is a vaccine-preventable disease, rabies still poses a significant public health problem in many countries in Asia and Africa where 95% of human deaths occur even with the available safe and effective vaccines for both human and veterinary use.
STAGES OF RABIES ATTACK
Rabies is infectious to mammals and essentially manifests in three stages. The first is a 1-3 days period which is characterized by behavioural changes and is known as the prodromal stage. The second is the excitative stage which lasts for 3-4 days. This is often known as “furious rabies” stage where the affected animal is hyper-reactive to external stimuli and can bite anything in close contact. The third is the paralytic stage which is associated with damage to motor neurons in the brain and other organs; and lasts beyond 4 days.
DIAGNOSIS OF RABIES
It is crucial to emphasize that the early stages of rabies before death can be difficult to diagnose. Epidemiologic factors such as season, geographic location, patient’s age, travel history and possible exposure to bites, rodents and ticks, may help direct the diagnosis. However, it is very important to note that no tests are currently available to diagnose rabies infection in humans before the onset of the clinical stage of the infection. And unless the rabies-specific signs of hydrophobia or aerophobia are present, the clinical diagnosis may be difficult.
SIGNS AND SYMPTOMS OF RABIES
Rabies signs and symptoms are progressive and vary with the stage of the infection. The signs and symptoms may include convulsions, unusual or unexplained tingling, pricking, burning or itching sensation at the bite site, low-grade fever (102o F or lower) and muscle spasms. Acute pain at the site of the bite, restlessness or abnormal behaviour, swallowing difficulty (drinking causes spasms of the voice box) due to paralysis of throat muscles and lack of coordination owing to rear limb paralysis are commonly observed. Other signs and symptoms are drooling or hyper salivation caused by paralysis of facial muscles, headache, general weakness or discomfort, insomnia, anxiety and confusion. There are presentations of slight or partial paralysis in an area of the body, agitation, hydrophobia (fear of water), delirium and aerophobia (abnormal and persistent fear of flying following severe anxiety).
COMPLICATIONS OF RABIES
Rabies presents some vital complications that bring it to the fore as a critical disease affecting humanity and other mammals. The complications include depression or periods of mania, lethargy, fatal inflammation of the brain and spinal cord, coma and death (caused by cardio-respiratory arrest) within days of the onset of severe symptoms.
MODE OF TRANSMISSION OF RABIES
Transmission of rabies virus usually begins when infected saliva of a host is passed to an uninfected animal. The most common mode of rabies virus transmission is through the bite and exchange of virus-containing saliva of an infected host. Transmission can also occur when infected material, usually saliva, comes into direct contact with human mucosa or fresh skin wounds. Human-to-human transmission by bite can be possible. Transmission through other routes such as contaminated mucous membranes (eyes, nose, mouth), aerosol and organ transplantations are rarely documented.
ANIMALS THAT CAN TRANSMIT RABIES
Most animals can be infected by rabies virus and can transmit the disease to humans and other animals. The vectors which most likely transmit the rabies virus include:
- Pets and farm animals which are cats, cows, dogs, ferrets, goats, horses, cattle and rabbits.
- Wild animals which are insectivorous bats, beavers, coyotes, weasels, bears, foxes, monkeys, wolves, raccoons, skunks, yellow mongoose and woodchucks.
- Principal rabies hosts: Generally, the principal rabies hosts and transmitters today are dogs, wild carnivores and bats. In Asia and parts of the Americas and Africa, dogs remain the principal host. The rabies virus survives in widespread rural fauna reservoirs. It is present in the animal populations of almost every country in the world.
VACCINATION AGAINST RABIES
Vaccines to prevent human rabies have been available for over one hundred years. Most deaths from rabies occur in countries with inadequate public health resources and limited access to preventive treatment. These countries also have few diagnostic facilities and almost no rabies surveillance. There is no specific treatment for rabies infection. Though a small number of people have survived rabies, the disease is usually fatal. For that reason, anyone thought to have been exposed to rabies receives series of shots of rabies vaccines to prevent the infection from taking hold and spreading to vital organs of the body.
Safe and effective vaccines can be used for pre-exposure vaccination. This is recommended for travelers who spend a lot of time outdoors, especially in rural areas, riding bicycle, camping or hiking as well as expatriates living in areas with significant risk of exposure to rabies. Pre-exposure vaccination is also recommended for people in certain high-risk occupations such as laboratory workers dealing with live rabies virus and other rabies-related viruses; and people involved in activities that might bring them professionally or otherwise into direct contact with rabid animals in rabies-infested areas. Children under 15 years of age, living in or visiting high risk areas are at higher risk and need to be vaccinated because they do play with animals and may receive more severe bites without reporting.
The most cost-effective strategy for preventing rabies in people is by eliminating rabies in dogs and other rabies prone animals through vaccination. Vaccination of animals, mostly dogs has decimated the number of human and animal rabies cases in several countries. However, recent increases in human rabies deaths in parts of Africa, Asia and Latin America suggest that rabies is re-emerging as a serious public health concern.
HOW TO STAY AWAY FROM RABIES INFECTION
It is important to avoid contact with biting mammals known to be rabies reservoir or vector species, and animals that look sick or has an abnormal behaviour. Wounds or mucous membranes contaminated with rabid animal’s saliva, unprovoked bite by an unvaccinated animal, unnecessary close contact with animals you are not familiar with and traveling or living in developing countries where rabies is more common including countries in Africa and Southeast Asia without adequate medical protection should be avoided.
Other things that need to be avoided are activities that are likely to put you in contact with wild animals that may harbour rabies virus, such as exploring caves where bats live or camping without taking precautions to keep wild animals away from campsite. Avoid working in a laboratory with the rabies virus without sufficient protection. Avoid wounds on the head or neck as much as possible so as to prevent rabies virus from rabid animals migrating to the brain more quickly. Handling wild animals or strays without adequate protection and the practice of allowing dogs to lick feces from the anus of children should be disallowed.
NECESSARY SAFETY PRECAUTIONS AGAINST RABIES VECTORS
Quickly go to the medical emergency room or promptly visit any health care provider if any animal bites you. Get vaccinated if you work in a high-risk occupation or travel to countries with high rate of rabies; and ensure your pets receive the proper vaccinations from qualified veterinarian. Follow quarantine regulations on importing dogs and other mammals into disease-free countries. Treat local wound or bite or scratch as soon as possible to prevent the onset of rabies and death. Wash the wound from an animal bite immediately with soap and water for 10 to 15 minutes and apply antiseptic such as povidone-iodine, iodine tincture, aqueous iodine solution or alcohol (ethanol) before contacting a healthcare provider to determine if post-exposure prophylaxis is needed. If any animal bites you, try to gather as much information about the animal as possible, call local animal control authorities to safely capture the animal and observe it for signs of rabies so as to guide appropriate medical action on you. If mucous membranes such as eyes, nose or mouth are exposed to rabies they should be flushed well with water immediately. Get within 10 days of infection, a course of potent and effective rabies vaccine or rabies immunoglobulin that meets WHO recommendations and keep pets under supervision.
Contact an animal control officer upon observing a wild or stray animal, especially if the animal is acting strangely. If you awake to find a bat in your room, assume that it have bitten you because a bat that flies into your room while you are sleeping may bite you without waking you. Also, if you find a bat near a person who cannot report a bite such as a small child or a person with disability, assume that the person has been bitten, so report such cases for immediate medical attention.
Keep your pets confined and supervise them when outside. This will help to keep your pets from coming in contact with wild animals especially rabid animals. Protect small pets like rabbits and guinea pigs from predators by keeping them inside or in protected cages so that they are safe from wild or rabid animals. Do not come into close contact with wild animals with rabies especially when they are unusually unafraid of people. Keep bats out of your home by sealing any cracks and gaps where bats can enter your home or seek help from local experts to keep bats out.