One-Health Approach – Prevention and Control of Rabies
M.Nithya Quintoil1, A.Varun1, M.Vigneswari1, M.Hariharan2 and N.Balamurugan2
1Assistant Professor, Rajiv Gandhi Institute of Veterinary Education and Research
2Field Veterinarian, Puducherry
Introduction:
Louis Pasteur, a renowned microbiologist, played an important role in the development of the rabies vaccine. He collaborated with many researchers and physicians to develop the vaccine for rabies. In 1885, Louis Pasteur succeeded against rabies by administering the experimental rabies vaccine to a 9-year-old boy named Joseph Meister who was bitten by a rabid dog and Pasteur immunized 50 dogs with the vaccine he developed against rabies. In 1884, Pasteur asked Dom Pedro II to authorize anti-rabies vaccine trials for the prisoners sentenced to death in South America. Rabies is a zoonotic, acute, progressive, and fatal viral disease of the central nervous system (CNS) caused by a enveloped bullet-shaped RNA virus. The disease is transmitted to humans and animals through close contact with saliva from infected animals. Pasteur’s work significantly contributed to the development of the rabies vaccine and its potential for combating the disease.
Epidemiology:
All warm-blooded animals are susceptible to rabies. In European countries, wildlife rabies has long been a serious problem since there is no effective diagnosis, isolation, animal management, or human treatment. Despite this, the number of recorded cases of rabies in wildlife has grown while canine rabies is declining in developed nations. Using attenuated and recombinant vaccines, oral vaccination techniques have eliminated rabies in several Western European nations and eastern Canada. In underdeveloped countries like Asia (India, Indonesia, Bangladesh, Bhutan, Myanmar, Nepal, Sri Lanka, and Thailand.), Africa (Nigeria, Liberia, Guinea, and Sierra Leone) where rabid dogs nearly invariably transmit human rabies cases. India is one of the countries with the largest number of cases reported, with 20,000 human deaths annually. The Association of the Prevention and Control of Rabies in India (APCRI) reported that Andaman, Nicobar, and Lakshadweep islands are free of the disease, while other parts of the country are highly affected. Over 99% of rabies cases globally are caused by the RABV that is prevalent in dogs. The international RABV lineage of dogs is said to have spread around the globe. The following nations are recognized as rabies-free: Fiji, Sweden, Caledonia, Scotland, Malta, Hawaii, England, Antigua, Singapore, Nevis, New Zealand, Vatican City, Guam, Grenadines, Turks, Lucia, Belgium, Aruba, Barbados, Australia, Ireland, Samoa, Bermuda, Ireland, Jamaica, Japan, and UK.
Pathogenesis:
Unlike other virus, the mechanism of action of virus on the host cell remains different. In the case of dog mediated transmission via the infected bite, the virus may multiply at the site of entry for a mean time, then the virus starts propagate into the peripheral nervous system slowly till it reaches the brain cells where it multiplies in enormous numbers. This period of time from the entry of virus to the exhibit of clinical signs from the animal or humans is known as incubation period of rabies. This incubation period varies from animal to animal depending on the site of bite. The closer the bite to the brain the incubation period will be very short. Similarly, the incubation period increases as the distance from the bite site or site of entry of virus the incubation period also increases. Once the virus gain entry into the nervous system then no vaccine or treatment works since the antibodies cannot attack nerve cells easily. These virus slowly move through the PNS and reach the brain cells where they multiply especially in purkinjee cells, thalamus, brain stem and spinal cord. They preferably multiply in almost all regions of the brain then they disseminate to all other organs after complete incubation period. The virus start to appear in all secretions of the human of the body especially saliva and they affect the peripheral and central nervous system combinely resulting in various nervous signs.
Clinical signs:
Clinical signs of rabies in humans and animals are almost same since they affect exactly same organs and cells in all species. After the virus multiply in the brain cells they propagate to to the PNS through the nerve cells and neuromuscular junctions reaching the target organs then exhibiting the clinical signs. The signs mostly of nervous form like seizures, hyper excitability, hallucinations, spasms and paralysis. Additionally they cause pain the muscles, dizziness, hydrophobia, fatigue, nausea, vomiting, aggression and irritability, dilated pupils, difficulty in swallowing, excess salvation, mental confusion and stiff neck. The death may occur due to brain death, self-starving due to inability to take food because of masticatory muscle paralysis. The three phases in clical rabies include Prodormal phase, Excitation phase, Paralytic phase. In the Prodormal phase the clinical signs start to appear and last for short days followed by the excitation phase where all the clinical aggrevate and finally leads to death. In certain dogs paralytic phase follows the excitation phase without progressing to death where in hydrophobia start to disappear and swallowing becomes possible, but the secretion still contain the viruses. The diagnosis is possible only after some clinical exhibit, since some nervous form diseases also have similar symptoms it is very mandatory to distinguish rabies and other diseases by proper diagnostic methods.
Transmission:
Rabies is caused by the lyssavirus family Rhabdoviridae which enters the salivary glands via cranial nerves during infection and is excreted in saliva. The most common way of transmission is through bites of infected animals which account for 85% – 95% of rabies cases in humans. Mortality depends on the virulence of the strain, location of the dog-bite wound, and amount of virus present in the saliva. Non-bite exposures include inhalation of aerosolized virus, or by contamination of open wounds, abrasions, mucous membranes with infected saliva. It is dangerous to handle rabid infected carcasses in butcher shops and slaughterhouses. Slaughtering of dog and the eating of dog meat are all thought to be significant factors in the prevalence of rabies in dog slaughterhouses.
Comprehensive One-Health Approach to Rabies
Fragmented approaches to rabies control result in a lack of coordination among government, NGOs, and private sector. A “One Health approach” based on cross-departmental collaboration is more effective. Collecting the required data and sharing the data between professional sectors can help in identifying the problematic areas and helps in the development of new management strategies, and overcoming the problems in lack of coordination between the sectors. World Health organization’s One Health Initiative, is in collaboration with global alliances, and focuses on a comprehensive approach that includes improved researches on medical interventions like vaccination, wound cleaning, post-exposure prophylaxis, and rabies prevention strategies to reduce the burden of rabies in humans. WHO is working towards achieving zero human deaths from rabies by 2030. The most effective short-term option is an integrated managemental strategy that links the veterinary and public health sectors. Long-term combining the measures at the local, national, and international levels, helps in permanent control can be achieved.
Prevention and control of rabies:
The control of rabies in developing countries is only possible by prevention of occurrence by proper pre exposure and post exposure for both humans and animals. The vaccine is cell cultured killed vaccine using beta- propiolactone which is completely safe for vaccination for both pre and post exposure. Pre- exposure vaccinations should be carried out to all dogs and cats which could have a human contact. In case of human’s people who are likely to handle dogs, cats and rabid animals, persons who handle viruses, Veterinary professionals should take pre exposure vaccinations. The post bite vaccinations are given to neutralize the viral antigen which could cause a disease. Species-specific Immunoglobulins can be given at the site of infection or bite which will neutralize the viral antigen at the site of bite itself, so that the possibility of infection can be further reduced. In case of dog bite, the site should be completely washed with soap or disinfectant, no suturing should be done unless it is long laceration and the bite wound should be treated only as an open wound. Mass vaccination by the government or NGOs of stray dogs can help in prevalence of the disease. Prevention is the only method to make an area or country free from rabies. Strict guidelines for vaccination, birth control and euthanasia of rabid animals can pave the way for the rabies free world.
