Can Rabies virus turn you into zombies?

Rabies Virus: Everything you need to know

Rabies virus belongs to the order Mononegavirales, viruses with a nonsegmented, negative-stranded RNA genomes. Within this group, viruses with a distinct “bullet” shape are classified in the Rhabdoviridae family, which includes at least three genera of animal viruses, Lyssavirus, Ephemerovirus, and Vesiculovirus.

rabies virus

The genus Lyssavirus includes rabies virus, Lagos bat, Mokola virus, Duvenhage virus, European bat virus 1 & 2 and Australian bat virus.

A. Structure:

Rhabdoviruses are approximately 180 nm long and 75 nm wide. The rabies genome encodes five proteins: nucleoprotein , phosphoprotein (P), matrix protein (M), glycoprotein (G) and polymerase (L).

All rhabdoviruses have two major structural components: a helical ribonucleoprotein core (RNP) and a surrounding envelope. In the RNP, genomic RNA is tightly encased by the nucleoprotein. Two other viral proteins, the phospo-protein and the large protein (L-protein or polymerase) are associated with the RNP.

The glycoprotein forms approximately 400 trimeric spikes which are tightly arranged on the surface of the virus. The M protein is associated both with the envelope and the RNP and may be the central protein of rhabdovirus assembly.

The basic structure and composition of rabies virus is depicted in the longitudinal diagram below.

Rabies is an RNA virus. The genome encodes 5 proteins designated as N, P, M, G, and L.

The order and relative size of the genes in the genome are shown in the figure below. The arrangement of these proteins and the RNA genome determine the structure of the rabies virus.

B. Transmission:

Rabies virus is transmitted through direct contact (such as through broken skin or mucous membranes in the eyes, nose, or mouth) with saliva or brain/nervous system tissue from an infected animal.

People usually get rabies from the bite of a rabid animal. It is also possible, but rare, for people to get rabies from non-bite exposures, which can include scratches, abrasions, or open wounds that are exposed to saliva or other potentially infectious material from a rabid animal.

Other types of contact, such as petting a rabid animal or contact with the blood, urine or feces of a rabid animal, are not associated with risk for infection and are not considered to be exposures of concern for rabies.

Other modes of transmission—aside from bites and scratches—are uncommon. Inhalation of aerosolized rabies virus is one potential non-bite route of exposure, but except for laboratory workers, most people won’t encounter an aerosol of rabies virus.

Rabies transmission through corneal and solid organ transplants have been recorded, but they are also very rare.

Bite and non-bite exposures from an infected person could theoretically transmit rabies, but no such cases have been documented.

Casual contact, such as touching a person with rabies or contact with non-infectious fluid or tissue (urine, blood, feces), is not associated with risk for infection. Contact with someone who is receiving rabies vaccination does not constitute rabies exposure, does not pose a risk for infection, and does not require postexposure prophylaxis.

Rabies virus becomes noninfectious when it dries out and when it is exposed to sunlight. Different environmental conditions affect the rate at which the virus becomes inactive, but in general, if the material containing the virus is dry, the virus can be considered noninfectious.

C. Sign and symptoms

After a bite or other rabies exposure, the rabies virus has to travel through the body to the brain before it can cause symptoms. This time between the exposure and the appearance of symptoms is called the incubation period, and it may last for weeks to months.

The incubation period may vary based on the location of the exposure site (how far away it is from the brain), the type of rabies virus, and any existing immunity.

The first symptoms of rabies may be very similar to those of the flu including general weakness or discomfort, fever, or headache. These symptoms may last for days.

There may be also discomfort or a prickling or itching sensation at the site of the bite, progressing within days to acute symptoms of cerebral dysfunction, anxiety, confusion, and agitation. As the disease progresses, the person may experience delirium, abnormal behavior, hallucinations, hydrophobia (fear of water), and insomnia.

The acute period of disease typically ends after 2 to 10 days. Once clinical signs of rabies appear, the disease is nearly always fatal, and treatment is typically supportive. To date less than 20 cases of human survival from clinical rabies have been documented, and only a few survivors had no history of pre- or postexposure prophylaxis.

The signs, symptoms, and outcome of rabies in animals can vary, but are often similar to those in humans, including early nonspecific symptoms, acute neurologic symptoms, and ultimately death.

D. Diagnosis:

In animals, rabies is diagnosed using the direct fluorescent antibody (DFA) test, which looks for the presence of rabies virus antigens in brain tissue. In humans, several tests are required.

Rapid and accurate laboratory diagnosis of rabies in humans and other animals is essential for timely administration of postexposure prophylaxis.

Within a few hours, a diagnostic laboratory can determine whether or not an animal is rabid and inform the responsible medical personnel.

The laboratory results may save a patient from unnecessary physical and psychological trauma, and financial burdens, if the animal is not rabid.

In addition, laboratory identification of positive rabies cases may aid in defining current epidemiologic patterns of disease and provide appropriate information for the development of rabies control programs.

The nature of rabies disease dictates that laboratory tests be standardized, rapid, sensitive, specific, economical, and reliable.

E. Prevention:

There are several things you can do to protect your pet from rabies.

#First, visit your veterinarian with your pet on a regular basis and keep rabies vaccinations up-to-date for all cats, ferrets, and dogs.

#Second, maintain control of your pets by keeping cats and ferrets indoors and keeping dogs under direct supervision.

#Third, spay or neuter your pets to help reduce the number of unwanted pets that may not be properly cared for or vaccinated regularly.

#Finally, call animal control to remove all stray animals from your neighborhood since these animals may be unvaccinated or ill.

The importance of vaccinating your pet:

While wildlife are much more likely to be rabid than are domestic animals in the United States, people have much more contact with domestic animals than with wildlife.

Your pets and other domestic animals can be infected when they are bitten by rabid wild animals, and this type of “spillover” increases the risk to people.

Keeping your pets up to date on their rabies vaccination will prevent them from acquiring the disease from wildlife, and thereby prevent possible transmission to your family or other people.