Rabies (Animal and Human)

Primary reference(s)

WHO, 2018. WHO Expert Consultation on Rabies. Third report. WHO Technical Report Series, No. 1012. World Health Organization (WHO). Accessed 12 October 2020.

WHO, 2020. United Against Rabies collaboration: First annual progress report. World Health Organization (WHO). Accessed 30 October 2020.

Additional scientific description

Rabies is a zoonotic disease (a disease that is transmitted from animals to humans), caused by the rabies virus, of the Lyssavirus genus, within the family Rhabdoviridae. Domestic dogs are the most common reservoir of the virus, with more than 99% of human deaths caused by dog-mediated rabies. Human infection occurs from bites of infected animals (usually dogs) and occasionally via penetrating scratches or licking of broken skin and mucosa. Domestic dogs, wild carnivore species and bats (Carnivora and Chiroptera) present a higher risk for rabies transmission than other mammals, as they are the reservoirs of the virus. Although monkeys, like any other mammal, are susceptible to rabies, the risk of rabies transmission from monkeys is extremely low. Infected animals may not appear rabid (NHS, no date).

Rabies is an acute, invariably fatal viral encephalitis. Initial signs include apprehension, headache, fever, malaise and sensory changes around the bite area. Excitability, hallucinations and abnormal fear of drafts of air (aerophobia) are common, followed in some cases by fear of water (hydrophobia) due to spasms of the swallowing muscles. Days after onset, the disease progresses to delirium, convulsions and death. Paralytic rabies is less common and is characterised by paralysis and loss of sensation, weakness and pain. Once clinical symptoms appear, rabies is virtually 100% fatal (WHO, 2018).

Rabies is present on all continents, except Antarctica, with over 95% of human deaths occurring in the Asia and Africa regions (WHO, 2021).

Although effective human vaccines and immunoglobulins exist for rabies, they are not readily available or accessible to those in need (WHO, 2020). Metrics and numeric limits Not applicable.

Metrics and numeric limits

Not applicable.

Examples of drivers, outcomes and risk management

Rabies has the highest case fatality rate of any currently recognised infectious disease. Rabies is present in mammals in most parts of the world. It is one of the Neglected Tropical Diseases (NTD) that predominantly affect poor and vulnerable populations who live in remote rural locations. The large majority of the estimated 59,000 human deaths from rabies per year occurs in Africa and Asia, with 80% in rural areas (WHO, 2019).

Children in regions of low-income countries enzootic for rabies have a higher risk of contracting rabies because of their size and behaviour (e.g., playing with animals, not reporting exposure) (WHO, 2019).

Vaccination against rabies is used to protect those at high risk of rabies exposure and prevent development of clinical rabies after suspected exposure, in conjunction with rabies immunoglobulin (postexposure prophylaxis) (WHO, 2019).

Assessment of individual risk of exposure to rabies virus is recommended for travellers. It should take into consideration: the remoteness of the destination, the prevailing rabies epidemiology and the cumulative duration of the stay(s) in endemic setting(s). In both no- and low-risk areas, proper medical care, rabies vaccine and immunoglobulins should be accessible in a timely manner, and reliable, laboratory-based surveillance of domestic, reservoir and wild species should be available. The level of risk is based on: the presence of animal species in which lyssaviruses are maintained (e.g., dogs, bats or other wildlife); the availability of reliable laboratory-based surveillance data on these species; access to proper medical care; and the availability of modern rabies vaccines (WHO, 2019).

Pre-exposure prophylaxis: Every country has rabies risk levels. These are (WHO 2019):

• Level 1: no risk. No pre-exposure prophylaxis required.
• Level 2: low risk. In both, no- and low-risk areas, proper medical care, rabies vaccine and immunoglobulins should be accessible in a timely manner, and reliable, laboratory-based surveillance of domestic, reservoir and wild species should be available. In countries in category 2 (low risk), pre-exposure prophylaxis should be offered to travellers involved in activities that are likely to bring them into direct contact with bats and wild carnivores. Such travellers include wildlife professionals, cavers, spelunkers, researchers, veterinarians and those visiting areas where bats and wild carnivores are commonly found. For people who regularly visit caves inhabited by bats, casual exposure to cave air is not a concern, but cavers should be warned not to handle bats.
• Levels 3 and 4: medium and high risk. In medium- and high-risk areas, access to proper medical care, rabies vaccines and immunoglobulins depends on the local setting. Timely access is not guaranteed everywhere because of a short supply of recent rabies vaccines or the local availability of older-generation rabies vaccines, which are no longer recommended by the WHO. Partial laboratory-based surveillance data may be available but may not cover all reservoir species or geographical settings in the country. Pre-exposure prophylaxis should therefore be considered for travellers who will undertake considerable outdoor activities in remote rural areas or activities that lead to probable contact with bats. Pre-exposure prophylaxis is also recommended for people with occupational risks, such as veterinarians, dog vaccinators and laboratory staff, and for expatriates living in remote areas with a significant risk of exposure to rabid domestic animals, particularly dogs, bats and wild carnivores.

Post-exposure prophylaxis: Every year, more than 29 million people worldwide receive a post-bite vaccination. This is estimated to prevent hundreds of thousands of rabies deaths annually. Globally, the economic burden of dog-mediated rabies is estimated at USD 8.6 billion per year (WHO, 2019).

Indications for post exposure prophylaxis depend on the type of contact with the confirmed or suspected rabid animal. Strict adherence to the WHO-recommended guidelines for optimal post exposure prophylaxis virtually guarantees protection from the disease. Administration of vaccine, and immunoglobulin if required, must be conducted by, or under the direct supervision of, a physician (WHO, 2019). Rabies immunoglobulin is not required for patients who have previously received two vaccine doses on different days.

Suspected contact in areas at risk of rabies may require post exposure prophylaxis. In this situation, immediate medical advice should be obtained. The category of exposure determines the indicated post-exposure prophylaxis procedure (WHO, 2019):

• Category I: touching or feeding animals, animal licks on intact skin (no exposure).
• Category II: nibbling of uncovered skin, minor scratches or abrasions without bleeding (exposure).
• Category III: single or multiple transdermal bites or scratches, contamination of mucous membrane or broken skin with saliva from animal licks, exposures due to direct contact with bats (severe exposure).

Controlling rabies in dogs: what to do - what to avoid doing? In brief, dog destruction alone is not effective in rabies control. There is no evidence that removal of dogs alone has ever had a significant impact on dog population densities or the spread of rabies. In addition, dog removal may be unacceptable to local communities. However, the targeted and humane removal of unvaccinated, ownerless dogs may be effective when used as a supplementary measure to mass vaccination. Mass canine vaccination campaigns have been the most effective measure for controlling canine rabies. High vaccination coverage (70% or higher) can be attained through comprehensive strategies consisting among others of well-designed educational campaigns, intersectoral cooperation, community participation and local commitment in planning and execution (WHO, no date).