Rabies is a viral disease that affects the central nervous system and is almost always fatal once symptoms appear. It is spread through the bite or scratch of an infected animal, most commonly dogs. Rabies has an incubation period that can last anywhere from 1-3 months before symptoms start to show. There is no cure for rabies once symptoms begin, but it can be prevented through vaccination either before or immediately after exposure. So can a person ever become immune to rabies if they receive the vaccine? Let’s take a closer look.
What is rabies?
Rabies is caused by the rabies virus, which is an RNA virus in the family Rhabdoviridae, genus Lyssavirus. While rabies symptoms in humans are distinctive, animals can display a range of symptoms including behavior changes, increased aggression, problems swallowing, paralysis, and fear of water. Left untreated, rabies has a mortality rate of nearly 100%.
The rabies virus is primarily passed from infected mammals through their saliva, most often through a bite. Infected saliva enters the body of the bitten animal or human, travels through the nerves to the spinal cord and brain where it causes inflammation (encephalitis). From there, the virus spreads through the rest of the body.
How is rabies transmitted?
The rabies virus is most commonly transmitted through:
– Bites from infected animals – This is the most common mode of rabies transmission to humans. Bites can introduce the virus directly into the bloodstream. Dogs are the most likely animal to transmit rabies through bites worldwide, but many other mammals can also spread the disease like this.
– Scratches from infected animals – Scratches can also transmit the rabies virus if saliva from an infected animal enters the wound.
– Contact with mucous membranes – If the saliva or nerve tissue from an infected animal makes contact with mucous membranes like the eyes, mouth, or nose, transmission is possible.
– Airborne transmission through bat caves – While rare, inhaling airborne rabies virus in an enclosed space heavily contaminated with infected bats is also a potential source of transmission.
– Rare transmissions – In very rare cases, rabies has been transmitted through organ transplants, exposure in laboratories, and contact with infected animal corneas.
What are the symptoms of rabies?
The initial symptoms of rabies can be similar to the flu including:
– Fever
– Headache
– General weakness or discomfort
– Sore throat
– Fatigue
– Loss of appetite
As the disease progresses and the virus spreads to the central nervous system, more specific symptoms set in such as:
– Tingling or itching sensation at the site of the bite
– Hallucinations
– Agitation
– Excess saliva production
– Muscle spasms
– Difficulty swallowing
– Hydrophobia (fear of water)
– Insomnia
Ultimately, in the disease’s final stages paralysis sets in, followed soon after by respiratory failure and death. The time from the initial flu-like symptoms to death is generally 2-10 days.
Is there a cure for rabies?
Unfortunately there is no effective cure for rabies once symptoms set in. For the small handful of people who have survived clinical rabies, intensive and lengthy medical intervention was required. Most rabies related deaths occur within days of symptoms appearing.
However, the disease is preventable if the rabies vaccine and immunoglobulin treatment are administered immediately after exposure and before symptoms start. The rabies vaccine works very effectively in preventing the disease before it takes hold in the body.
Can you become immune to rabies?
Yes, it is possible to become immune to the rabies virus by receiving vaccinations before exposure. Here is how rabies immunity works:
Pre-exposure vaccinations
Pre-exposure rabies vaccinations are recommended for anyone with a higher risk of contracting the diseases, such as:
– Veterinarians
– Animal control officers
– Laboratory workers who handle samples containing the virus
– Travelers going to countries where rabies is more common
The rabies vaccine is administered as a series of 3-4 shots over the span of a month. The initial dose primes the immune system, followed by subsequent doses to strengthen the antibody response over time.
This allows people’s bodies to develop immunity to rabies before any exposure occurs. If a pre-vaccinated person is later exposed to rabies, they still require two vaccine boosters but do not need the rabies immunoglobulin shot.
Post-exposure treatment
Those who have not received pre-exposure vaccinations can still develop immunity after potential rabies exposure. This post-exposure treatment consists of:
– A dose of human rabies immunoglobulin (HRIG) – This provides some immediate antibodies until the vaccine has time to build up immunity. The HRIG is injected at the exposure site to provide faster protection to the central nervous system.
– A series of 4 rabies vaccine doses over 14 days – This triggers the immune system to start producing its own antibodies against the rabies virus. The vaccines are effective in preventing the virus from progressing if administered promptly after exposure.
How long does rabies immunity last?
The rabies antibodies created after vaccination provide immunity that lasts for years. On average, the rabies vaccine protects for:
– Pre-exposure – Immunization with the 3-4 dose series typically protects for 2-3 years initially. Booster shots are recommended after that time to maintain immunity.
– Post-exposure – The 4 dose vaccine series along with HRIG after an exposure provides immunity for at least 6-12 months. Additional boosters may be suggested after a year.
Can you get rabies if vaccinated?
It is extremely rare for someone who completed the full course of pre- or post-exposure rabies vaccinations to still contract the disease. However, no vaccine is 100% effective.
According to the CDC, there have been at least 15 documented cases of vaccine failures worldwide, most due to improper vaccine administration. It’s estimated that the rabies vaccine confers immunity in over 99% of those vaccinated. Prompt administration and completion of the vaccine regimen offers the best protection.
Who is at higher risk of rabies?
While any mammal can contract and transmit rabies, the level of risk depends on several factors:
Geographical location
Rabies risk is higher in certain regions of the world:
| Region | Estimated rabies deaths per year |
|---|---|
| Africa | 24,000 |
| Asia | 35,000 |
| Americas | 2,500 |
| Europe | 2,900 |
Rabies is considered endemic in many parts of Asia, Africa, and Central and South America. Certain countries like India and China see thousands of rabies deaths annually. Travelers to these higher risk areas have a greater chance of exposure.
Occupational exposure
People who frequently come in contact with animals like veterinarians, wildlife specialists, and animal control personnel have higher occupational exposure risks. Animal shelters, kennels, and laboratories handling rabies also pose more risk.
Lack of animal vaccinations
In areas where routine pet vaccination is less common, stray dog populations are larger, or wild animals like foxes and raccoons harbor more rabies, human transmission is more likely. Vaccination of domestic dogs and cats is key to reducing this risk.
Age and inability to communicate
Younger children who cannot effectively communicate and report exposures are at increased risk. Bites and scratches can go unnoticed and unreported more easily with small children.
Conclusion
While a rabies infection often leads to a tragic outcome, there are preventive steps that can be taken:
– Pre-exposure vaccination if at higher risk
– Avoiding contact with wild animals
– Promptly washing bite and scratch wounds
– Reporting any potential exposure to medical professionals
– Receiving post-exposure treatment if exposed
Vaccination continues to be the most effective strategy we have to prevent rabies virus from taking hold in the body after an exposure. While not 100% protective, today’s modern rabies vaccines confer immunity and protection from this dangerous disease in nearly all who receive them. Being proactive and avoiding high risk situations remains our best defense against rabies.
