Preventing And Detecting RabiesPosted On:2016-02-19 Category:
Major facts On Rabies
- Rabies is a vaccine-preventable viral disease which occurs in more than 150 countries and territories.
- Dogs are the source of the vast majority of human rabies deaths.
- Rabies elimination is feasible by vaccinating dogs.
- Infection causes tens of thousands of deaths every year, mostly in Asia and Africa.
- 40% of people who are bitten by suspect rabid animals are children under 15 years of age.
- Immediate wound cleansing with soap and water after contact with a suspect rabid animal can be life-saving.
- Every year, more than 15 million people worldwide receive a post-bite vaccination to prevent the disease; this is estimated to prevent hundreds of thousands of rabies deaths annually.
Rabies is an infectious viral disease that is almost always fatal following the onset of clinical signs. In more than 99% of human cases, the rabies virus is transmitted by domestic dogs. Rabies affects domestic and wild animals, and is spread to people through bites or scratches, usually via saliva.
Rabies is present on all continents with the exception of Antarctica, but more than 95% of human deaths occur in Asia and Africa.
Rabies is a neglected disease of poor and vulnerable populations whose deaths are rarely reported and where human vaccines and immunoglobulin are not readily available or accessible. It occurs mainly in remote rural communities where children between the age of 5–14 years are the most frequent victims.
The average cost of rabies post-exposure prophylaxis (PEP) can be the cost of catastrophic expenses for poor populations, since a course of PEP can cost US$ 40 in Africa and US$ 49 in Asia, where the average daily income is about US$ 1–2 per person.
Eliminating rabies in dogs
Rabies is a vaccine-preventable disease. Vaccinating dogs is the most cost-effective strategy for preventing rabies in people. Dog vaccination will drive down not only the deaths attributable to rabies but also the need for PEP as a part of dogbite patient care.
Preventive immunization in people
The same safe and effective vaccines can be used for pre-exposure immunization. This is recommended for travellers spending a lot of time outdoors, especially in rural areas, involved in activities such as bicycling, camping, or hiking as well as for long-term travellers and expatriates living in areas with a significant risk of exposure.
Pre-exposure immunization is also recommended for people in certain high-risk occupations such as laboratory workers dealing with live rabies virus and other rabies-related viruses (lyssaviruses), and people involved in any activities that might bring them professionally or otherwise into direct contact with bats, carnivores, and other mammals in rabies-affected areas. As children are considered at higher risk because they tend to play with animals, may receive more severe bites, or may not report bites, their immunization could be considered if living in or visiting high-risk areas.
The incubation period for rabies is typically 1–3 months, but may vary from <1 week to >1 year. The initial symptoms of rabies are fever and often pain or an unusual or unexplained tingling, pricking or burning sensation (paraesthesia) at the wound site. As the virus spreads through the central nervous system, progressive, fatal inflammation of the brain and spinal cord develops.
Two forms of the disease can follow. People with furious rabies exhibit signs of hyperactivity, excited behaviour, hydrophobia and sometimes aerophobia. After a few days, death occurs by cardiorespiratory arrest.
Paralytic rabies accounts for about 30% of the total number of human cases. This form of rabies runs a less dramatic and usually longer course than the furious form. The muscles gradually become paralyzed, starting at the site of the bite or scratch. A coma slowly develops, and eventually death occurs. The paralytic form of rabies is often misdiagnosed, contributing to the under-reporting of the disease.
No tests are available to diagnose rabies infection in humans before the onset of clinical disease, and unless the rabies-specific signs of hydrophobia or aerophobia are present, the clinical diagnosis may be difficult. Human rabies can be confirmed intra-vitam and post mortem by various diagnostic techniques aimed at detecting whole virus, viral antigens or nucleic acids in infected tissues (brain, skin, urine or saliva).
People are usually infected following a deep bite or scratch by an infected animal. Dogs are the main host and transmitter of rabies. They are the cause of human rabies deaths in Asia and Africa.
Bats are the source of most human rabies deaths in the Americas. Bat rabies has also recently emerged as a public health threat in Australia and western Europe. Human deaths following exposure to foxes, raccoons, skunks, jackals, mongooses and other wild carnivore host species are very rare.
Transmission can also occur when infectious material – usually saliva – comes into direct contact with human mucosa or fresh skin wounds. Human-to-human transmission by bite is theoretically possible but has never been confirmed.
Rarely, rabies may be contracted by inhalation of virus-containing aerosol or via transplantation of an infected organ. Ingestion of raw meat or other tissues from animals infected with rabies is not a source of human infection.
Post-exposure prophylaxis (PEP)
Post-exposure prophylaxis (PEP) means the treatment of a bite victim that is started immediately after exposure to rabies in order to prevent rabies infection. This consists of:
- local treatment of the wound, initiated as soon as possible after exposure;
- a course of potent and effective rabies vaccine that meets WHO standards; and
- the administration of rabies immunoglobulin, if indicated.
Effective treatment soon after exposure to rabies can prevent the onset of symptoms and death.
Local treatment of the wound
This involves first-aid of the wound that includes immediate and thorough flushing and washing of the wound for a minimum of 15 minutes with soap and water, detergent, povidone iodine or other substances that kill the rabies virus.
Depending on the severity of the contact administering with the suspected rabid animal, administration of PEP is recommended as follows.
All category II and III exposures assessed as carrying a risk of developing rabies require PEP. This risk is increased if:
- the biting mammal is a known rabies reservoir or vector species;
- the animal looks sick or displays an abnormal behaviour;
- a wound or mucous membrane was contaminated by the animal’s saliva;
- the bite was unprovoked; and
- the animal has not been vaccinated.
In developing countries, the vaccination status of the suspected animal alone should not be considered when deciding whether to initiate prophylaxis or not.
The Organization continues to promote human rabies prevention through the elimination of rabies in dogs as well as a wider use of the intradermal route for PEP which reduces volume and thereby the cost of cell-cultured vaccine by 60% to 80%.
WHO, in close collaboration with the Food and Agriculture Organization of the United Nations (FAO), the World Organisation for Animal Health (OIE) and the Global Alliance for Rabies Control, is raising awareness of and commitment to overcoming this persistent zoonosis in endemic countries.
Great strides have been made in the Philippines, South Africa and Tanzania where a project is underway as part of a Bill & Melinda Gates Foundation project led by WHO. The key towards sustaining and expanding the rabies programmes to new territories and countries has been to start small, demonstrate success and cost-effectiveness, and ensure community engagement.
Stockpiles of dog and human rabies vaccine have had a catalytic effect on rabies elimination efforts in countries.
Rabies transmitted by dogs has been eliminated in many Latin American countries, including Chile, Costa Rica, Panama, Uruguay, most of Argentina, the states of São Paulo and Rio de Janeiro in Brazil, and large parts of Mexico and Peru.
Many countries in the WHO South-East Asia Region have embarked on elimination campaigns in line with the target of regional elimination by 2020. Bangladesh launched an elimination programme in 2010 and, through the management of dog bites, mass dog vaccination and increased availability of vaccines free of charge, human rabies deaths decreased by 50% during 2010–2013......
Reference:World Health Organisation Report 2015