Rabies
Name(s):
Hydrophobia
Lyssa
Nature
Rabies is an acute viral infection of the central nervous system which affects virtually all mammals, including man, and occasionally occurs in birds. The final stage of rabies infection is coma, cardiac or respiratory failure. In humans the disease is almost always fatal. There have been only 3 reported rabies survivors.
In the western countries, the principal vectors (transmitters) are wild animals - especially bats, foxes, skunks, raccoons and the like, but due to a lack of dog vaccination and control programmes, dogs remain the major vector in Third World countries. Other common vectors are domestic cats, jackals, mongooses and, particularly in countries in western Asia, wolves. However, the range of infected animals in Third World countries is so wide (including livestock and rodents) that rabies should be suspect in any animal bite.
Although in terms of the traditional measures of incidence and mortality in man, rabies cannot be considered an important disease in comparison with many other conditions, the economic costs of rabies cannot be neglected. First, even where incidence is zero, significant and continuing costs are incurred for the surveillance and prevention of outbreaks, such as quarantine regulations, publicity campaigns and the investigation of persons exposed outside the country. Second, sizeable resources are committed in many countries to control the incidence and spread of infection among animals, both domestic and wild. Third, in infected areas there may be significant indirect costs, whereby the presence of rabies lowers the national income from tourism and various forms of agriculture, because of fear of infection.
Background
One of the oldest recorded infectious diseases, rabies was first described by Democritus (500 BC). It was first noted in Asia and Europe, the first case being recorded in the USA in 1812, in Brazil in 1911.
Rabies is characterized by nervous derangement with paralysis in the final, and sometimes in the intermediate stages, resulting in death. The virus is present in the saliva of affected animals, and is transmitted by biting. The average incubation period is 2-12 weeks, rarely less than 10 days, rarely more than 6 months; the incubation period is shorter for young animals. There are two distinct forms; dumb and furious rabies. Dumb rabies symptoms are: apathy; nervousness; lack of coordination, finally paralysis, especially of the lower jaw and hind quarters in dogs; ultimate death. In furious rabies, the excitation period (which also occurs in dumb rabies) is more pronounced, manifesting restlessness, viciousness, difficulty in chewing and swallowing; the apathy period at the start is less pronounced, equally the final stage of paralysis may be shorter.
Incidence
This disease is of great importance to livestock in the South and Central American zones where paralytic rabies is transmitted by blood-lapping bats. Thousands of cattle die annually of the disease and expenditure on vaccination and other control measures is high. In central Europe, wildlife rabies is the predominant form of the disease: foxes are the main victims and at the same time also the main vectors of the infection in this region. But canine rabies is the prevailing source of the disease. Dogs, particularly stray dogs, are an important reservoir of infection in Africa, Central and South America, Asia and also in Greece. Bites by rabid dogs are responsible for the vast majority of all human cases of rabies - 90% or more - and a similar proportion of post-exposure treatment occurs in countries affected with canine rabies. Increased urbanization, the more widespread practice of camping, and increased international travel by man and transfer of animals, increase the rabies risk. Organ transplants, particularly corneal transplants, have also been a concealed means of transmission of rabies to man.
Rabies has almost been eradicated within the European Union and future efforts will concentrate on vaccination of foxes in the few remaining infected areas. The success of the campaign can be judged, for example, from the fact that in the most infected Member State (Germany) only 108 cases have been reported in 1998 compared to 855 in 1995 and 3534 in 1991. The objective of the campaign is to eliminate the threat to humans and animals and to allow people to have a more intimate safer contact with nature. It will also contribute to dismantling quarantine for pets when they and their owners travel to the United Kingdom or Ireland (the pilot pet passport scheme began in January 2000). It can be confidentially expected that rabies will be eliminated from the EU within the not too distant future. The year 2000 programmes include 2.9 million euro towards the continuation of this campaign.
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Reference(s)
Type
(E) Emanations of other problems