First Rabies patient to survive

Rabies is caused by a rhabdovirus which infects the central nervous tissue and salivary glands of a wide range of mammals, and is usually conveyed, by saliva, through bites or licks on abrasions or on intact mucous membranes. Man is most frequently infected from dogs. In Europe the maintenance host is the fox and in recent years the zoonosis has spread from Poland westwards through Germany and France.

The incubation period, during which the virus is spreading centripetally along axons to the brain, varies in man from a minimum of 9 days to many months but is usually between 4 and 8 weeks. Severe bites, especially on head or neck are associated with short incubation period.

Clinical Features

Only a proportion of people bitten by rabid animal develop the disease, but once menifest it is almost always fatal. At the onset there may be fever and paraesthesia at athe sit of the bite. Prodromal period of 1 to 10 days during which the patient is increasingly anxious, leads to characteristic fear of water, "Hydrophobia". Although the patient is thirsty attempts to drink water lead to violent contraction of muscles of diaphragm and other inspiratory muscles and thereafter even the sight or sound of water may provoke distressing spasms and attacks of panic. Delusions, hallucination may develop with spitting biting and mania. Cranial nerve lesions develop with terminal hyperpyrexia. Death occurs within a week of the onset of symptoms. In some ascending paralysis is seen without mental excitment, and these patients servive on average 12 days.

Investigation

Diagmnosis is usually on clinical grounds.

Immunofluoroscent techneques can detect antigen in the corneal smear impression and skin biopsies.

Management

Only a few patients with rabies have survived, and all of them had received some form of prophylaxis and needed intensive care to control respiratory and cardiaac failure. Once symptoms appear only palliative measures cn be taken.

Prevention

Pre-exposure prophylaxis is a must for those at a risk with antirabies vaccination.

Post-exposure prophylaxis

* Thorough cleaning of the wound with detergents or soap.

* Damaged tissue to be excised and wound left unsutured.

* Antirabies vaccine: The safest vaccine is the Human Diploid Cell Strain Vaccine. 1.0 ml given in the deltoid region days 0,3,7,14,30,90

* Human rabies Immunoglobulin 20 I.U. / Kg bwt. Half of the dose is infiltrated around the wound and the remaining half is given I.M. Hyperimmune animal serum 40 I.U. / Kg bwt.may also be used.

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Rabies Transmission by Oral and Other Non-bite Routes

Rabies transmission by oral route is a queer mode of infection. Reports of oral transmission are infrequent and hence need elaborate discussion. Evidences of such transmission have been well documented in men. Transmission of rabies virus to humans by ingestion of milk from a rabid mother has been reported. A woman in early stage of rabies transmitted the disease to her nursing baby.

Transplacental transmission is another unique mode of spread of this disease. Transplacental transmission was observed in an infant born of a Turkish woman who died of rabies following dog bite. Authentic reports of airborne infection are available. In 1956 an entomologist who frequently visited bat infested caves in USA for research studies developed laboratory proven rabies after aerosol inhalation. Out of two instances of rabies transmitted to laboratory workers by aerosol inhalation, one recovered after intensive therapy but the other died.

Rabies virus has been isolated from several body fluids like saliva, tracheal and nasal secretions, tear, CSF, urinary sediment, etc, from laboratory proved case of human rabies. None the less rabies transmission from human patients to healthy contacts is extremely rare.One important mode of non-bite transmission from man to man is by corneal transplantation from unrecognised infected donor. Several cases have been observed since the first case was reported in 1979. Public health importance of oral and other non-bite routes of infection is worth considering. Consumption of infected milk from a rabid cow is not uncommon because consumers become aware of disease in an animal only after using milk for several days. However, reported instances of rabies among cow milk consumers are rare because boiling of milk is a common practice in endemic countries, which is adequate to destroy the virus. None the less under certain circumstances such as wrestlers in the Northern India and for worship purpose in Eastern States only raw milk is used when comsumers are exposed to the risk of infection. In such a situation rabies prophylaxis is mandatory.

Under no circumstances should a cornea be transplanted from a donor, who died of an undiagnosed neurological disorder. Medical, nursing personnels, laboratory workers, and other attendants should use gowns, gloves, goggles for personal protection. In the event of unavoidable exposure immunisation against rabies must not be omitted.

-- Dr. JK Dutta