• Rabies is a viral infection of mammals. It is transmitted from animal to animal or from animal to human. Human infection usually occurs as a result of a transdermal bite or scratch from an infected animal.
• Dogs are the principal vector causing transmission of rabies to humans in Asia, parts of Latin America and large parts of Africa - although all mammals are potential hosts for rabies virus.
• There are no immediate clinical symptoms following exposure to rabies virus. Once infection occurs the virus multiplies and then spreads to the central nervous system. The incubation period in humans averages between 20 and 90 days.
• Once the rabies virus reaches the brain, the first clinical symptoms appear. These are generally non-specific and flu-like. In addition, pain or paresthesia (tingling sensations and/or itching) at the wound site is common.
• The disease quickly progresses to an acute neurologic phase. There is no treatment and death follows rapidly.
• Rabies has the highest case fatality rate of any known infectious disease and is virtually 100% fatal following the onset of clinical symptoms. The only way to prevent clinical rabies after exposure and infection is by vaccination.

Yes, modern safe effective vaccines can prevent the disease.
There are two active immunization strategies available to prevent rabies in humans:

• pre-exposure vaccination protects against potential exposure to rabies and is particularly valuable for individuals who live in or travel to high-risk areas or work in high-risk occupations
• post-exposure prophylaxis (PEP) is administered following contact with a suspected or confirmed rabid animal.

The WHO provides guidelines for both strategies.

The rabies virus belongs to the family Rhabdoviridae, genus Lyssavirus.
Viruses in the family Rhabdoviridae are characterized by their distinct ‘bullet’ shape. There are two main structural components of the virus:

• a phospholipid envelop with surface glycoprotein spikes
  (G-protein) - fusion of the rabies virus envelop with the host cell membrane initiates the infection process
• a helical ribonucleoprotein (RNP) core and N-protein - encases genomic, negative, non-segmented, single-stranded RNA What does the rabies virus look like?

The rabies virus has a distinct ‘bullet’ shape, characteristic of the family Rhabdoviridae to which it belongs.

Rabies occurs worldwide, with very few countries or regions being considered 'rabies free'. Rabies virus circulates in a variety of mammalian hosts or 'reservoirs' depending on the geographic location. In North America, wild animal reservoirs include raccoons, skunks, foxes and bats, whereas in Europe, foxes and bats are the main reservoirs. In developing countries, rabies mainly circulates in the dog population and thousands of human fatalities are caused every year by bites from rabid dogs. Additionally, rabies can transfer or 'spill over' from infected wildlife reservoirs to non-reservoir animals (e.g. cats, monkeys, horses, cattle, sheep and goats).

In about 100 countries worldwide, rabies is enzootic in wild and/or domestic animals and poses a threat to more than 3 billion people living in these areas. Rabies exposure is reported most frequently in cities, where there are large populations of both dogs and humans. However, this may be due to the fact that victims exposed to potentially rabid animals generally travel to large anti-rabies clinics located in cities to seek PEP (Post-exposure prophylaxis).

In many industrialized countries, animal rabies has been brought under control through the use of oral rabies vaccination programs in wildlife and/or mandatory parenteral vaccination of domestic animals. The implementation of these animal vaccination programs, along with the advent of modern tissue culture-derived human rabies vaccines, has resulted in a dramatic decrease in the number of human rabies deaths reported in industrialized countries.

The WHO considers some island countries such as the UK, Iceland and Japan to be free of terrestrial rabies, as well as some European countries including Spain, Portugal, Greece, Sweden, Finland and Norway.

The administration of rabies vaccine invokes a cellular and humoral immune response in the patient (active immunity). Circulating RVNA (Rabies virus neutralizing antibodies) are usually detectable within 7 to 10 days after administration of the first injection of vaccine and persist for 2 or more years. In addition, rabies vaccines induce an anamnestic response (i.e. fast production of RVNA due to the presence of immune memory cells) when they are administered to individuals who have been vaccinated previously.

Presently, a number of different types of rabies vaccines are available for use. Cell-culture rabies vaccines are used in North America and western Europe and their use is increasing in popularity in South East Asia, and the Middle East. Unfortunately, many countries in Asia, Africa and Latin America that have a high-risk status for contracting rabies, and would benefit significantly from modern rabies vaccines, are still relying on crude nerve-tissue vaccines for PEP.

Countries in North America and western Europe only use modern cell-culture rabies vaccines. The use of cell-culture rabies vaccines is increasing throughout South East Asia, Middle East and Latin America. Unfortunately, countries in Asia, Africa and Latin America, where rabies is enzootic, still rely heavily on nerve-tissue vaccines.

Louis Pasteur developed the first human rabies vaccine over 100 years ago. The first vaccines were crude by today’s standards, but were the first successful means of providing protection against the disease. Since then the development of rabies vaccines has progressed significantly. Modern cell-culture rabies vaccines are highly efficacious, pure and have excellent safety profiles.