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Why does Rabies Cause Hydrophobia?

We’re all familiar with the disease rabies – whose most widespread symptom is fear of water or hydrophobia. So, what are the causes and symptoms of rabies, and how does rabies cause hydrophobia?

Table of Contents

1. What is Rabies?

Rabies is a fatal (deadly) but preventable viral disease from the rhabdovirus family. The rabies virus belongs to the genus Lyssavirus and is mostly transmitted through the saliva of infected animals, from their bites and scratches. The rabies virus attacks a person’s central nervous system (CNS), eventually causing coma and death.

why does rabies cause hydrophobia
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In North America, this virus is typically found in wild animals such as bats, foxes, and raccoons, whereas dogs are the most common carriers in other parts of the world. Rabies causes tens of thousands of deaths each year, mainly in Asia and Africa.

2. What are the Types of Rabies?

There are approximately six types of rabies.

2.1. Furious Rabies (Classical Rabies)

Furious rabies is an aggressive kind of rabies and is found in both animals and humans. This type of rabies is characterized by acute symptoms like extreme agitation, aggression, and, of course, hydrophobia (extreme and irrational fear of water), which is the most widespread symptom of rabies infection. Let us look at how furious rabies progresses with time.

cats and dogs
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2.1.1. The Prodromal stage

This is the initial stage of furious rabies. This stage may last between 2 to 10 days after the rabies virus has infected a human or an animal. The symptoms typical of this stage of rabies include fever, malaise, and discomfort at the area of the bite or scratch wound.

2.1.2. The Furious Stage

At this stage, patients (both humans and animals) start showing severe restlessness, hyperactivity, and aggression. Victims become agitated very quickly and may even bite or attack others. As the disease progresses, the infected animal or human starts suffering from hallucinations and delirium, thus losing touch with reality. The furious stage may sometimes manifest as photophobia (extreme fear and sensitivity to light) and phono phobia (extreme fear and sensitivity to sound).

aggressive cat
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2.1.3. Hydrophobia

Hydrophobia, i.e., extreme and irrational fear of water, is the most popular and key symptom of furious rabies. This happens because of painful throat spasms that victims suffer from; these spasms are triggered by attempting to swallow liquids, thus causing hydrophobia in the infected being. Even the sight or sound of water could trigger severe anxiety and convulsions in rabies patients at this stage.

2.1.4. Seizures & Paralysis

At this stage of the disease, patients often experience seizures and spasms paired with progressive paralysis. In most cases, paralysis leads to respiratory failure and, eventually, coma and death.

Preventive measures include Pre-Exposure Vaccination, Post-Exposure Prophylaxis (PEP), and Animal Vaccination and Control.

angry cats
Photo by Marián Šicko, pexels

2.2. Dumb Rabies (Paralytic Rabies)

This is the second clinical form of rabies and is also called Guillain-Barré-like rabies. The dumb or paralytic form of rabies is characterised by progressive paralysis without an initial furious phase in patients. Animals with dumb rabies typically appear to be depressed and lethargic and show muscle weakness and a lack of coordination. This kind of rabies is found in about 20 to 30 percent of the cases.

2.3. Bat Rabies

Bat rabies is a variant of the rabies virus that primarily affects bats. The bats, in these cases, act as natural reservoirs for the multiplying rabies virus; this results in a unique and challenging case of rabies infection and transmission.

Some species of bats, such as the Eptesicus fuscus or Big Brown Bat, Lasionycteris noctivagans or Silver-Haired Bat, and Lasiurus borealis or Red Bat, are the most common carriers of bat rabies.

Areas where bat rabies is prevalent include North America (mostly in certain areas of the United States and Canada), Latin America, Africa, Asia (India has reported several cases of bat rabies) and Australia.

bats
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2.4. Wild Animal Rabies

Wild animal rabies is an umbrella term for the forms of rabies that primarily affect mammals in the wild; this type is most commonly found in raccoons, foxes, skunks, and bats. Wild animals are more likely to carry the disease without displaying obvious symptoms of it which makes it extremely difficult to detect rabies in them at early stages. Pet animals, if come in contact with wild animals, are at a higher risk of rabies exposure.

2.5. Domestic Animal Rabies

As the name suggests, this refers to rabies infection in domestic animals or pets. This type of rabies infection is primarily found in dogs, cats, and livestock (cattle, horses, and goats), commonly owned and kept by people. Domestic animals are at a high risk of exposure to rabies if they roam around freely or come in contact with other animals (whether pets, strays, or wild animals).

Therefore, you must keep your animals vaccinated at all times. Regular vaccinations and medical check-ups will ensure your pets aren’t infected with rabies.

2.6. Human Rabies

Rabies infection in humans is rare compared to its prevalence in animals, but the number of cases of human rabies isn’t meager. Rabies is fatal in human beings as well, though a tiny percentage of patients manage to survive with severe neurological problems for the rest of their lives.

3. How is Rabies Infection Transmitted?

Rabies is spread mainly through one’s contact with the saliva of an infected animal. Here are some ways this virus is transmitted in:

3.1. Bite or Scratch

bite
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These are the most common ways of transmission of the rabies virus. When a rabid animal bites or scratches another animal or human being, the saliva that contains the virus is introduced into the bite or scratch wound and infects the victim.

3.2. Mucous Membranes

Rabies infection can also spread if an infected animal’s saliva somehow comes in contact with mucous membranes or open wounds on someone else’s body. Mucus membranes in your body refer to moist surfaces of the eyes, nose and mouth. A rabid animal’s saliva contains the rabies virus, so if it comes in contact with another animal/human’s mucous membranes, the disease is transmitted to them.

3.3. Inhalation

Though extremely rare, inhalation of aerosolized rabies virus is a potential non-bite route exposure. But this only happens to laboratory workers and researchers as laymen wouldn’t even encounter an aerosol of rabies virus.

4. What are the Stages of Rabies Infection?

Rabies infection is a fatal disease that generally progresses in stages and becomes more and more severe with time. The stages of rabies infection are stated and explained below:

4.1. The Incubation Period

The duration of the incubation stage of rabies infection typically ranges from anywhere between weeks to months. No visible symptoms of rabies is found in this initial stage. Still, the virus in the bite or scratch wound is continuously multiplying and travelling along the peripheral nervous system to reach the central nervous system (CNS) ultimately.

4.2. The Prodromal Stage

The prodromal stage of rabies generally lasts for about 2 to 10 days, and the symptoms at this stage are not specific and may resemble other illnesses such as flu. Some such symptoms include fever, headache, fatigue, muscle aches and weakness, irritability and pain or tingling at the site of the wound.

4.3. The Acute Neurological Stage (Furious Rabies)

This stage lasts for about a few days to a week and is characterized by severe neurological symptoms that are key symptoms of rabies. The symptoms found in patients at this acute stage of rabies are as follows:

4.3.1. Hydrophobia

Rabies causes hydrophobia, which is a term used to describe a condition where a patient has extreme and irrational fear of water. This happens due to painful throat spasms in rabies patients.

4.3.2. Difficulty Swallowing

Rabies causes paralysis of the infected animal/human’s throat muscles. This make it difficult for the infected animals or humans to swallow.

4.3.3. Hallucinations

Vivid hallucinations also characterize rabies infection in the acute stage. Patients lose touch with reality, and this leads to feelings of agitation as well as confusion.

4.3.4. Agitation & Restlessness

Rabies patients show severe agitation and restlessness quite often. This happens mainly because they experience vivid hallucinations, lose touch with reality and display erratic behaviour from time to time.

4.3.5. Muscle Spasms

In rabies patients, muscle spasms are very common. Muscles throughout the patient’s body often goes into spasms or convulsions.

4.3.6. Paralysis

Rabies causes paralysis, which gets more and more acute with time as the disease progresses and eventually causes respiratory failure in patients.

4.4. Paralytic Stage (Dumb Rabies)

The duration of this stage is variable, and it may follow the furious rabies stage. The paralytic stage of rabies infection is characterized by severe and progressive paralysis, muscle weakness and a loss of co-ordination in victims. This stage is different from the furious rabies stage because hydrophobia and agitation are less common here.

4.5. Coma and Death

These are the last stages of the fatal disease. Rabies virus causes severe damage to the CNS which ultimately causes coma in patients and death eventually occurs primarily due to respiratory failure.

5. How do we know if an Animal has Rabies?

Unless tested, there is no such sure way of knowing if an animal has a deadly rabies infection. But certain common symptoms are generally seen in rabid animals. Some common and well-known symptoms that rabies-infected animals show include:

5.1. Unprovoked Aggression

Rabid animals often become extremely aggressive without any provocation at all. They show hostility and aggression towards people as well as other animals. This is one of the most apparent signs that the rabies virus has infected an animal.

5.2. Disorientation

Animals infected by rabies may sometimes show signs of disorientation and confusion. Stumbling, walking in circles, and having difficulty coordinating their movements are signs that an animal is quite possibly rabid.

5.3. Drooling and Difficulty Swallowing

Rabies causes paralysis of throat muscles, which makes it difficult for victims to swallow anything. As a result, they may drool and show difficulty in eating or drinking. This is another apparent sign that an animal has a deadly rabies infection.

5.4. Unusual Vocalizations

Rabid animals make strange noises that are uncharacteristic of them. Unusual whining, howling, or growling, which are not typical of its species, may mean the animal is rabid. These are signs to look out for to determine whether an animal is rabies-infected.

5.5. Paralysis

Rabies virus causes paralysis, especially in the hind legs. So, if an animal is seen suddenly dragging its rear legs or unable to stand or walk, it is likely to be rabid. Though these signs could be the consequences of a physical injury, if you see them in addition to other signs that align with symptoms of rabies infection, it is best to maintain distance from the animal as the animal is possibly infected with the fatal or deadly virus.

5.6. Excessive Salivation

This is another well-known symptom of rabies and is seen in almost all cases, especially in rabid animals. This increased salivation leads to ‘foaming of the mouth’; this symptom is typical and common in animals with rabies infection.

5.7. Nocturnal Animals Activity During the Day

Rabies affects normal behaviour of infected animals. Nocturnal animals such as bats and raccoons may be active even during the daylight if they are infected with the fatal rabies virus.

5.8. Erratic Behavior

As mentioned earlier, rabies alters the infected animals’ normal behaviour and thought processes. This causes rabid animals to show erratic behaviour quite often.
In case you notice any or some of these symptoms in stray animals, it is best to keep a safe distance. Please do not approach them or try to touch or handle them in any way, as the animal may attack you and infect you with this deadly virus.

6. Can Human Beings Get Rabies?

Though rabies is a zoonotic disease (i.e., it is mainly found in animals), it can also be transmitted to human beings and is equally deadly for them. Every year, rabies causes around 59,000 human deaths worldwide. Rabies in humans is relatively lower when compared to infection in animals, yet the number of human deaths it causes every year is not very low. Also, rabies in human beings is 99% fatal.

7. Symptoms of Rabies in Humans

rabies symptoms in humans
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The initial symptoms of this fatal disease are almost the same as that of the flu. Symptoms are the same as having flu, like fever, headache, and general weakness, and can last for a few days. Besides these symptoms, the site of the bite or scratch of the rabid animal will be uncomfortable as well as cause a pricking or an itchy sensation.

Once the disease progresses, victims start experiencing more severe symptoms, such as delirium, hallucinations, insomnia, and hydrophobia. These are the clinical symptoms of rabies infection, and after they appear, the condition of the patient gets worse and they eventually enter a comatose state and die.

8. Has anybody ever Survived Rabies?

Up to January 2023, there have been 30 well-documented cases of human rabies survivors. These patients did not receive timely administration of a full course of a recommended post-exposure rabies prophylaxis regimen, and only a minority received rabies immune globulin. Also, these cases do not include patients who had atypical features of the rabies infection without the development of rabies virus-neutralizing antibodies (as they were likely not cases of rabies), and reports that did not have sufficient documentation.

9. Why is Rabies Difficult to Treat?

Generally, viral infections can be easily treated using anti-viral drugs, which inhibit virus development in the body. But in case of the rabies virus, this is not quite possible because it uses many strategies to avoid the victim’s immune system and hide itself from the anti-viral drugs.

10. What is Hydrophobia?

The word Hydrophobia refers to the extreme and irrational fear of water. This condition is typical to rabies patients and is considered a hallmark symptom of rabies. Hydrophobia occurs when the rabies infection is at its acute stage due to severe throat spasms and difficulty in swallowing.

11. Why does Rabies cause Hydrophobia?

Rabies causes severe throat spasms in the infected animals/humans and, eventually paralysis of the throat muscles. These spasms make it difficult for victims to swallow even liquids. This reaches to a point where even the thought of drinking water may trigger convulsions in infected beings. This is how rabies infection leads to hydrophobia.

12. How to Prevent Rabies Infection?

As rabies is fatal, prevention of this infection is absolutely necessary. Stated below is a list if things that we should do in order to prevent rabies infection in animals as well as humans.

12.1. Vaccination of Domestic Animals

vaccination of pets
Photo by Karolina Grabowska, pexels

Vaccinating your pets is one of the most effective ways to prevent rabies infection in domestic animals. Domestic dogs are often infected with this deadly virus, so regular vaccination of pets is necessary; regular vaccinations will ensure your pet doesn’t get the infection even if it is somehow exposed to the rabies virus.

12.2. Responsible Pet Ownership

Please ensure your pets are under control and do not let them roam outside freely. This will help in preventing contact with stray animals who are generally carriers of rabies virus. Also, if other stray/wild animals bite your pet or show unusual behaviour and have an unexplained illness, you need to seek medical help immediately.

12.3. Wildlife Management

In the areas where the rabies virus is prevalent amongst wild animals, wildlife management needs to take action to prevent the spread of this virus. Certain measures must be implemented, including vaccinating wild animals to avoid infection and to removing rabid animals in a way considered humane.

12.4. Pre-Exposure Prophylaxis (PrEP)

People who are at higher risk of rabies infection, for example, veterinary doctors, and animal control workers and researchers, should be vaccinated beforehand to make sure they are protected. Pre-exposure prophylaxis (PrEP) consists of a series of rabies vaccinations that provide a person with added protection in case of potential exposure to the virus.

12.5. Avoiding Contact with Wild Animals

Wild animals in numerous parts of the world carry the rabies virus, with some species being at a higher risk of spreading it to others. Thus, it is best not to contact wild or stray animals at all. Bats, raccoons and stray dogs are some of the most common carriers of this deadly virus.

12.6. Prompt Medical Attention

In case you are bitten or scratched by an animal or feel you have been exposed to the virus in any way, seek medical help as soon as possible. This will help prevent the manifestation of this fatal disease.

12.7. Public Health Education

Public health education campaigns would be a great way to raise awareness regarding dangers of rabies exposure. Also, these campaigns will help promote responsible behaviour around animals. Moreover, with the help of these campaigns, people will be able to recognize the risks regarding the rabies virus and take appropriate steps if exposed to it.

12.8. Safe Handling of Bats

Bats, the only flying mammals, often act as reservoirs for the fatal rabies virus in various parts of the world (mentioned earlier); therefore, safe handling of bats is a crucial step to take in order to prevent the spread of rabies. In case you find a bat inside your house, it is best not to handle it yourself. You need to call for local animal control or wildlife removal experts to get rid of the bat.

12.9. Travel Precautions

If you plan on visiting places where rabies is prevalent or areas where medical assistance is hard to find, it is best to get your vaccines before the trip to be safe. Also, do your best to avoid contact with animals in those regions.

12.10. Global Efforts

The government can play a crucial role in controlling and eliminating rabies through introduction and implementation of mass vaccination campaigns for pet animals, and other public health initiatives.

13. What to do if a rabid animal bites you?

Here are the steps that you need to follow if a rabid animal bites or scratches you.

13.1. Step 1: Safety is the First Priority; Protect Yourself

First, prioritize moving away from the infected animal as quickly and safely as possible. You must not try to touch, capture or handle the animal in any way, as the rabid animal may attack you again and cause more severe infection. Moreover, if possible, put a barrier between yourself and the animal, such as a vehicle or a closed door, in order to avoid further contact with the animal.

wound on nose
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13.2. Step 2: Clean the Wound Thoroughly

Wash the scratch or bite wound thoroughly with soap and water to minimize your chances of infection. If available, you can also use an antiseptic solution such as hydrogen peroxide or iodine. It is best not to apply alcohol on the wounded area or other substances that may irritate the bite or scratch wound.

13.3. Step 3: Seek Immediate Medical Attention

You need to go to a hospital or emergency room or contact a healthcare provider immediately after you’ve been bitten.

Inform your healthcare provider that you have been bitten by a potentially rabid animal and provide as much information as you can about the infected animal, such as its species, colour, behaviour, etc. The rabies vaccine PEP (post-exposure prophylaxis) needs to be administered immediately in order to prevent the onset of symptoms of rabies infection.

13.4. Step 4: Rabies Vaccination and Rabies Immune Globulin (RIG)

The post-exposure prophylaxis, or PEP in short, involves a series of rabies vaccines. This series of vaccinations are administered to stimulate the patient’s immune system in order to trigger the production of antibodies to fight the deadly rabies virus.

13.5. Step 5: Report The Incident

It is very important to report such incidents to animal control and public health authorities. Once you report the incident, the animal will be spotted and captured by the authorities and tested for rabies. Make sure you provide accurate details regarding the animal’s appearance and behaviour.

13.6. Step 6: Follow Medical Advice

medical advice
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Follow the treatment plan that your health provider has prescribed; the treatment plan may involve a series of rabies vaccinations over the course of a few weeks. Even if the animal that bit you isn’t rabid, completing the rabies vaccination course is important. So, please do not drop it midway.

14. Conclusion

Rabies infection, to date, continues to be a serious public health concern worldwide. Though the spread of this disease is at a minimum in developed countries, developing nations are more often the victims of this fatal infection.

This write-up has highlighted the importance of responsible pet ownership, proper behaviour around animals, and steps to take in case you have been exposed to this deadly virus. With proper vaccination programmes, precautions and awareness worldwide, alleviating rabies infection, both among animals and humans, will become much easier.

Last Updated on December 19, 2023 by soubhik92@gmail.com