An introduction to Rabies (Hydrophobia)
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Dr Asem Suresh Kumar Meitei
Contd from previous issue
The diagnosis of rabies is based entirely on the demonstration of Negri bodies in the central nervous system and on the results of small animal inoculations. The histological examination of the central nervous system is obviously the method of choice as it can be carried out in a matter of few hours. When Negri bodies can be demonstrated, ther is no doubt about the presence of rabies, but a negative or doubtful histological examination is much less reliable. Unless small animal inoculations are performed many negative diagnosis are liable to be made in animals that are definitely infected. Intra-cerebral inoculation of Swiss mice with suspected brain material is a much more reliable method of diagnosis rabies than the demonstration of Negri bodies. Paralytic symptoms of infected mice are usually manifested in about seven days. When Negri bodies are present in sufficient numbers they can be readily demonstrated in smears or impressions of Ammon’s horn and can be stained with Seller’s carbolFuchsin or methylene blue. Fluorescent antibody test is the one which gives very quick and reliable diagnosis of rabies. For this one needs the specific test reagent and an access to a fluorescent microscope.
Once the symptoms of rabies develop, treatment of ant form is useless. Until now, treatment of rabies means treatment of exposed individuals with a course of suitable antirabies vaccine. Recently, drugs like Doxuridine, Vidarabine and Acyclovir are reported to be useful in the treatment of exposed cases of rabies before development of clinical symptoms. These drugs are not yet available in India.
In an enzootic country like India, every case or individual bitten by a carnivorous animal should be treated for rabies without any doubt. Treatment should commence within seven days of exposure. Even, anti-rabies vaccinated (prophylactically) dog has been bitten by a suspected rabid dog, it should also be treated for rabies.
Treatment
1) No treatment should be attempted after clinical signs are evident. Immediately after exposure irrigation of the wound with 20% soap solutions or a solution of Zephiran (bezalkonium chloride) may prevent the establishment of the infections. Post–exposure vaccination is unlikely to be of value in animals, as death usually occurs before appreciable immunity has had time to develop.
2) Euthanasia of suspect animals must be prevented, particularly if human exposure has occurred, since the development of the disease in the animals is necessary to establish a diagnosis.
3) For the treatment of animals, phenol or beta-propiolactone inactivated five percent sheep brain tissue anti rabies vaccine made with the classical Pasteur (Paris) or Flury or Kelev strain is used.
4) The Pasteur (Paris) strain of virus is the one which was originally used by Pasteur and his co-workers for preparation of ARV.
5) Flury strain of rabies virus was isolated from a girl, Flury, who died of rabies after exposure to the licks in a wound by a rabid dog.
6) Kelev strain was isolated from a rabid dog.
These are fixed virus and suitable for production of ARV.
The same vaccine is used in humans. Use of brain tissue vaccine in human has a disadvantage in the form of post-vaccinalneuro—paralytic reaction. A human diploid cell inactivated rabies vaccine is available for treatment of man exposed to rabies.
While treating individuals, especially man, with brain tissue ARV, special attention should be given for a reaction, known as post–vaccinalneuro-paralytic paralytic reaction. The symptoms provoked are of the nature of allergic responses. Acute urticarial, syncope and oedema may occur soon after an injection in individuals who have been sensitized by a previous injection. But in those who have not been treated before, symptoms of erythema a, oedema, pruritus and pain may develop around the site in about a week.
Prophylactic anti rabies vaccination is used in India usually in dogs, cats and other carnivorous pet animals. In some countries of the Latin America and Islands of the Caribbean sea cattle as well as humans are prophylactically vaccinated with ARV. This has to be done in these places due to prevalence of a blood sucking bat, known as vampire bat, which acts as a vector and reservoir of rabies.
For prophylactic vaccination ARV of 20 percent strength of sheep brain tissue is used. First vaccination should be done at the age of six months. The second dose vaccine after six months of the first vaccination and then annually to be done.
Prevention & Control
The complete details of programmes for rabies control include control of the disease in dogs, other domestic animals, wildlife and bats, etc.
1) Vaccination against rabies and registration of cats and dogs.
2) Promotion of responsible animal ownership
3) Management of stray animal populations
4) Oral vaccination of wildlife reservoirs, if possible where there is a high risk of the disease.
5) Mass Education to avoid exposure to suspect rabid animals
(To be contd)
Contd from previous issue
The diagnosis of rabies is based entirely on the demonstration of Negri bodies in the central nervous system and on the results of small animal inoculations. The histological examination of the central nervous system is obviously the method of choice as it can be carried out in a matter of few hours. When Negri bodies can be demonstrated, ther is no doubt about the presence of rabies, but a negative or doubtful histological examination is much less reliable. Unless small animal inoculations are performed many negative diagnosis are liable to be made in animals that are definitely infected. Intra-cerebral inoculation of Swiss mice with suspected brain material is a much more reliable method of diagnosis rabies than the demonstration of Negri bodies. Paralytic symptoms of infected mice are usually manifested in about seven days. When Negri bodies are present in sufficient numbers they can be readily demonstrated in smears or impressions of Ammon’s horn and can be stained with Seller’s carbolFuchsin or methylene blue. Fluorescent antibody test is the one which gives very quick and reliable diagnosis of rabies. For this one needs the specific test reagent and an access to a fluorescent microscope.
Once the symptoms of rabies develop, treatment of ant form is useless. Until now, treatment of rabies means treatment of exposed individuals with a course of suitable antirabies vaccine. Recently, drugs like Doxuridine, Vidarabine and Acyclovir are reported to be useful in the treatment of exposed cases of rabies before development of clinical symptoms. These drugs are not yet available in India.
In an enzootic country like India, every case or individual bitten by a carnivorous animal should be treated for rabies without any doubt. Treatment should commence within seven days of exposure. Even, anti-rabies vaccinated (prophylactically) dog has been bitten by a suspected rabid dog, it should also be treated for rabies.
Treatment
1) No treatment should be attempted after clinical signs are evident. Immediately after exposure irrigation of the wound with 20% soap solutions or a solution of Zephiran (bezalkonium chloride) may prevent the establishment of the infections. Post–exposure vaccination is unlikely to be of value in animals, as death usually occurs before appreciable immunity has had time to develop.
2) Euthanasia of suspect animals must be prevented, particularly if human exposure has occurred, since the development of the disease in the animals is necessary to establish a diagnosis.
3) For the treatment of animals, phenol or beta-propiolactone inactivated five percent sheep brain tissue anti rabies vaccine made with the classical Pasteur (Paris) or Flury or Kelev strain is used.
4) The Pasteur (Paris) strain of virus is the one which was originally used by Pasteur and his co-workers for preparation of ARV.
5) Flury strain of rabies virus was isolated from a girl, Flury, who died of rabies after exposure to the licks in a wound by a rabid dog.
6) Kelev strain was isolated from a rabid dog.
These are fixed virus and suitable for production of ARV.
The same vaccine is used in humans. Use of brain tissue vaccine in human has a disadvantage in the form of post-vaccinalneuro—paralytic reaction. A human diploid cell inactivated rabies vaccine is available for treatment of man exposed to rabies.
While treating individuals, especially man, with brain tissue ARV, special attention should be given for a reaction, known as post–vaccinalneuro-paralytic paralytic reaction. The symptoms provoked are of the nature of allergic responses. Acute urticarial, syncope and oedema may occur soon after an injection in individuals who have been sensitized by a previous injection. But in those who have not been treated before, symptoms of erythema a, oedema, pruritus and pain may develop around the site in about a week.
Prophylactic anti rabies vaccination is used in India usually in dogs, cats and other carnivorous pet animals. In some countries of the Latin America and Islands of the Caribbean sea cattle as well as humans are prophylactically vaccinated with ARV. This has to be done in these places due to prevalence of a blood sucking bat, known as vampire bat, which acts as a vector and reservoir of rabies.
For prophylactic vaccination ARV of 20 percent strength of sheep brain tissue is used. First vaccination should be done at the age of six months. The second dose vaccine after six months of the first vaccination and then annually to be done.
Prevention & Control
The complete details of programmes for rabies control include control of the disease in dogs, other domestic animals, wildlife and bats, etc.
1) Vaccination against rabies and registration of cats and dogs.
2) Promotion of responsible animal ownership
3) Management of stray animal populations
4) Oral vaccination of wildlife reservoirs, if possible where there is a high risk of the disease.
5) Mass Education to avoid exposure to suspect rabid animals
(To be contd)