Are Tetanus and Rabies Related?

Overview

You probably have a vague idea about two diseases (Rabies and tetanus) whose symptoms include very strange behaviour/mannerisms. And you're wondering if they are closely related. To be concise, they are not! 

While both tetanus and rabies are infectious diseases that cause muscle spasms (among other things), they are quite dissimilar. We will look into the things they have in common and how they differ below.

Are tetanus and rabies rare diseases?

The rabies virus is found on all continents except Antarctica, and the organism that causes tetanus is commonly found in soil, on rusty objects like nails, and in human and animal feces.^1,2

Both diseases can therefore occur in most parts of the world. As to whether they are rare, the answer is yes (in part). Yes, they are rare in developed countries; but they occur more often in developing countries where vaccination rates are lower.^1,2

Rabies cause 59,000 deaths (worldwide) every year, and more than 29 million people receive the rabies vaccine after an animal bite. Similarly, there were about 73,000 reported cases of tetanus globally in 2019^.2,3

What is tetanus and how do you get it

Tetanus is caused by a bacterium called Clostridium tetani which is commonly found in the environment. You can get the infection when an open wound comes in contact with the organism, which releases a toxin (tetanus toxin) that is carried to the brain and spinal cord via blood.

Here, the toxin interferes with chemicals that prevent continuous muscle contractions. This results in repeated muscle spasms, which could begin anytime between 3-21 days after infection - on average about 8 days.⁴ 

Common symptoms of tetanus include:

• Lockjaw/trismus - which results from spasm of jaw muscles
• Repeated, painful muscle spasms throughout the body which could be triggered by noise or light, and could result in difficulty breathing or swallowing
• Fever
• Sweating
• Fast heartbeat

What is rabies and how do you get it

Rabies is caused by a Lyssavirus. It results from the bite or scratch of an infected animal - which in 99% of cases, is a dog. In developed countries, because of widespread dog vaccinations, other animals like bats are responsible. The disease is uncommon in developed countires;  95% of human rabies occurs in Africa and Asia.²

Once the virus is introduced into the body, it travels to the brain where it multiplies and causes inflammation (swelling), leading to disease symptoms. It also travels to other parts of the body - like the salivary glands - through the nerves. Rabies often (almost 100% of the time) result in death once symptoms begin.^2,5

It presents in two distinct forms:

1. Encephalitic/furious rabies - about 80% of rabies patients show symptoms that are in keeping with this form of rabies.² These include:
   • Initial non-specific symptoms - fever, feeling unwell, headache
   • Tingling at the site of the animal bite
   • Painful throat spasms - these occur initially on attempts to drink water, leading to a fear of water (hydrophobia). As the disease progresses, the thought or sight of water can trigger these spasms. A draft of air in the patient’s face can also cause spasms - leading to the fear of air (aerophobia)
   • Foaming at the mouth - from increased salivation
   • Spasms of other muscles in the body
   • Confusion and aggressive behavior
   • Seeing or hearing things that aren't there (hallucinations)

2. Paralytic/dumb rabies - only about 20% of rabies cases present like this. Paralysis begins - usually from the bite site - and gradually spreads to other parts of the body, leading to a coma. The dramatic symptoms of encephalitic rabies are absent here²

What are the similarities between tetanus and rabies

What are the differences between tetanus and rabies

Are tetanus and/or rabies vaccinations required after a dog bite?

Yes, the World Health Organization (WHO) recommends a rabies vaccine after an animal bite or any contact between an open wound and a dog’s body fluids - like saliva. As there is no effective treatment for rabies, prevention is paramount; seek medical attention immediately after any animal bite or possible animal contact with broken skin. 

The WHO also recommends tetanus vaccination after animal bites in some cases because of the risk of a tetanus infection. Your healthcare provider will assess your risk of tetanus and determine if you need the vaccine.⁶

About Vaccinations

The best time to start the rabies vaccination series (post exposure prophylaxis (PEP)) is as soon as possible after exposure. PEP administration is only too late once the symptoms of rabies begin.⁷

In certain groups - like people who work closely with animals - the rabies vaccine can be given to protect against rabies in the absence of rabies exposure. This is called pre-exposure prophylaxis (PrEP). If you believe you need rabies PrEP, speak to your healthcare provider about your eligibility for the vaccine.

Unlike the rabies vaccine, the tetanus vaccine is given routinely in the childhood immunization schedule - this is the reason why tetanus is rarely seen in the developed world. Booster doses of the vaccine may be required after possible exposure to tetanus as post-exposure prophylaxis. Again, this will be decided by your treating physician; and it is best given as soon as possible after an injury.

In some cases, you might be given both vaccines at the same time, at separate body sites. You are also likely to be given rabies immune globulin and tetanus immunoglobulin.

Other Important Information

Dogs are responsible for a vast number of cases of human rabies; mass dog vaccination in the developed world has played a large role in containing the disease in these parts. However, rabies can also be transmitted from the bites of other domestic animals like cats, and wild animals like bats, foxes, and skunks.^8,9

Tetanus can also be acquired in:

• People who inject drugs - due to drug contamination with the bacteria¹⁰
• Babies (neonatal tetanus) - from non-sterile practices around care of the umbilical cord like cutting it with contaminated instruments, or using contaminated material(s) to care for the cord stump. Women of reproductive age should be immunized to prevent this since maternal protection also protects the baby; good cord care practices are also important^1,11
• Diabetic patients with wounds (diabetic ulcers)

Summary

Tetanus and rabies are two life-threatening infectious diseases. While they share some similarities, their differences are significant enough to warrant their consideration as separate disease entities. They are both difficult to treat and prevention remains the cornerstone of management for both. Speak to your healthcare provider as soon as you believe you have been exposed to either one!