Rabies

Rabies is a severe disease, which almost always leads to death if not treated immediately.

Causes
The rabies virus is present in the saliva of infected animals, and is spread when the saliva gets into the skin through a bite or a scratch. The majority of cases of rabies are caused by dogs, but other animals that can spread rabies include cats, bats and monkeys.

A bite through clothing is less risky, as the clothing absorbs some of the saliva. High risk exposures are bites or scratches on the face or neck, large or deep wounds or multiple bites. Bites that bleed indicate a deep wound. Licks on broken skin are also considered high risk.

Signs and Symptoms
Initially there is an incubation period that usually lasts one to three months, however longer or shorter incubation periods are possible.

In the early stages of the disease there may be a low grade fever, fatigue, weakness, muscle ache and headache. The bite wound often has altered sensation, such as tingling, itching, burning, tenderness or numbness.

Some patients will develop discomfort in the throat and difficulty swallowing. As the disease progresses the muscle in the throat begin to spasm when water is swallowed. This causes an intense fear of water, and even the mention of water can trigger these spasms.

There may be confusion, hallucinations, seizures and an increased production of saliva and increased sweating. Agitation and aggression is also common, with thrashing and biting. However, there might also be occasional episodes of calmness.

The muscles can tense, including the muscles in the face. As the disease progresses further, the muscles become weak and voluntary movement is not possible. As neurological functioning declines, coma follows. Eventually, the respiratory muscles also weaken, leading to respiratory arrest and death. 

Investigations
Patients that present without symptoms do not need investigations, only immediate treatment with vaccines.

Only advanced investigations can confirm the diagnosis of rabies (such as biopsy from the neck), which is reserved for patients that present with advanced disease (such as neurological dysfunction).

A blood glucose must be checked on anyone with altered mental status.

If the animal has been captured, then it should be sent to a veterinarian for investigations.

Treatment
The rabies vaccine must be given before any symptoms occur. The vaccine must be administered into the deltoid muscle immediately (this is known as day 0). The vaccine must then be repeated on days 3, 7 and 14. An additional dose is given on day 28 for those that have impaired immunity. Rabies is usually prevented when the regime is followed correctly and commenced before symptoms appear. A reduced regime is required for patients who have had completed a pre-exposure prophylaxis regime within the last 5 years.

High risk bites also require immunoglobulin to be administered. Immunoglobulin must be administered around and underneath the bite wound. Any immunoglobulin remaining must be administered into the gluteus.

The rabies vaccine regime can be discontinued if the animal remains healthy for a period of 10 days, or if the animal is found to be negative for rabies after reliable laboratory investigations. If the animal was not caught, then the full treatment regime must be followed.

The wound should be cleaned immediately, with thorough flushing with povidone iodine (or soap and water) for 15 minutes. Suturing is generally avoided, however if unavoidable then the wound should first be infiltrated with immunoglobulin and suturing delayed several hours. As with any wound, careful exploration for foreign objects is required and dead tissue debrided. Antibiotics and tetanus vaccination may also be required depending on the wound. 

If the patient presents with advanced disease then they must be cared for in a quiet room. Palliative care must include sedation and pain control. Staff and people in close contact with the patient must wear personal protection, such as gloves, masks and eye protection.

If the patient is unconscious then an open airway must be maintained, and oxygen administered as required.