Rabies Treatments

Post-exposure prophylaxis

Treatment after exposure, known as post-exposure prophylaxis or “P.E.P.”, is highly successful in preventing the disease if administered promptly, generally within ten days of infection. Thoroughly washing the wound as soon as possible with soap and water for approximately five minutes is very effective at reducing the number of viral particles. “If available, a virucidal antiseptic such as povidone-iodine, iodine tincture, aqueous iodine solution or alcohol (ethanol) should be applied after washing...Exposed mucous membranes such as eyes, nose or mouth should be flushed well with water.” In the United States, patients receive one dose of ''human rabies immunoglobulin'' (HRIG) and four doses of rabies vaccine over a fourteen day period. The immunoglobulin dose should not exceed 20 units per kilogram body weight. HRIG is very expensive and constitutes the vast majority of the cost of post-exposure treatment, ranging as high as several thousand dollars. As much as possible of this dose should be infiltrated around the bites, with the remainder being given by deep intramuscular injection at a site distant from the vaccination site. The first dose of rabies vaccine is given as soon as possible after exposure, with additional doses on days three, seven and fourteen after the first. Patients that have previously received pre-exposure vaccination do not receive the immunoglobulin, only the post-exposure vaccinations on day 0 and 3.

Modern cell-based vaccines are similar to flu shots in terms of pain and side effects. The old nerve-tissue-based vaccinations require multiple painful injections into the abdomen with a large needle, are cheap, and are now used only in remote poor areas in India, but are being phased out and replaced by affordable WHO ID (intradermal) vaccination regimens.

Intramuscular vaccination should be given into the deltoid, not gluteal area which has been associated with vaccination failure due to injection into fat rather than muscle. In infants the lateral thigh is used as for routine childhood vaccinations.

Finding a bat in the room of a sleeping infant is regarded as an indication for post-exposure prophylaxis. The recommendation for the precautionary use of post-exposure prophylaxis in occult bat encounters where there is no recognized contact has been questioned in the medical literature based on a cost-benefit analysis. However, recent studies have further confirmed the wisdom of maintaining the current protocol of precautionary administering of P.E.P. in cases where a child or mentally compromised individual has been left alone with a bat, especially in sleep areas (where a bite/or exposure may occur while the victim is asleep and unaware or awake and unaware that a bite occurred). This is illustrated by the case of a nine-year old boy from Quebec who died an agonizing death (over a 14 day period) from rabies 4 weeks after being in the presence of a sick bat, even though there was no apparent report of a bite; as shown in the following conclusion made by the doctors involved in the case:

Despite recent criticism (45), the dramatic circumstances surrounding our patient's history, as well as increasingly frequent reports of human rabies contracted in North America, support the current Canadian guidelines which state that RPEP is appropriate in cases where a significant contact with a bat cannot be excluded (46). The notion that a bite or an overt break in the skin needs to be seen or felt for rabies to be transmitted by a bat is a myth in many cases.

It is highly recommended that P.E.P. be administered as soon as possible. Begun without delay, or with very little delay, P.E.P. is 100% effective against rabies. In the case in which there has been a significant delay in administering P.E.P., the treatment should be administered regardless of that delay, as it may still be effective if it is not too late. If there has been a delay between exposure and attempts at treatment, such that the possibility exists that the virus has already penetrated the nervous system, the possibility exists that amputation of the affected limb might thwart rabies, if the bite or exposure was on an arm or leg. This treatment should be combined with an intensive PEP regimen.

Blood-brain barrier

Some recent works have shown that during lethal rabies infection, the blood-brain barrier (BBB) does not allow anti-viral immune cells to enter the brain, the primary site of rabies virus replication. This aspect contributes to the pathogenicity of the virus and artificially increasing BBB permeability promotes viral clearance. Opening the BBB during rabies infection has been suggested as a possible novel approach to treat the disease, even though no attempts have yet been made to determine whether or not this treatment could be successful.

Induced coma

In 2005, American teenager Jeanna Giese survived an infection of rabies unvaccinated. She was placed into an induced coma upon onset of symptoms and given ketamine, midazolam, ribavirin, and amantadine. Her doctors administered treatment based on the hypothesis that detrimental effects of rabies were caused by temporary dysfunctions in the brain and could be avoided by inducing a temporary partial halt in brain function that would protect the brain from damage while giving the immune system time to defeat the virus. After thirty-one days of isolation and seventy-six days of hospitalization, Giese was released from the hospital.

Giese's treatment regimen became known as the "Milwaukee protocol". To date only one other patient has survived under the protocol, despite numerous attempts at the treatment. Rodney Willoughby Jr., Giese's primary care physician, has asserted that subsequent failures occurred because patients were not given the same combination of drugs used in the initial incident.

On April 10, 2008 in Cali, Colombia, an eleven year-old boy was reported to survive rabies and the induced coma without noticeable brain damage.

Ketamine

The anesthetic drug ketamine has shown the potential for rabies virus inhibition in rats.

Further Reading


This article is licensed under the Creative Commons Attribution-ShareAlike License. It uses material from the Wikipedia article on "Rabies" All material adapted used from Wikipedia is available under the terms of the Creative Commons Attribution-ShareAlike License. Wikipedia® itself is a registered trademark of the Wikimedia Foundation, Inc.

Last Updated: Feb 1, 2011

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