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Hydrophobia is characterised by painful and involuntary throat spasms caused by the rabies virus. These throat spasms can make it painful and extremely difficult to swallow water. Even though it is a physiological condition, the symptoms of hydrophobia can make it appear that an individual is experiencing a phobia of water.
Hydrophobia only occurs in late-stage rabies and is almost always followed by death. Today, we are going to look at hydrophobia in more detail, including the common characteristics, causes, symptoms and diagnosis.
What is hydrophobia?
Hydrophobia is so named because it appears to be characterised by a fear of water. However, unlike other phobias, hydrophobia doesn’t actually involve the usual psychological symptoms, such as fear, anxiety or panic. Instead, hydrophobia is symptomatic of the rabies infection. It occurs during the later stages of the virus and results in involuntary and painful spasms in the throat that occur when drinking or thinking about drinking water. Hydrophobia usually develops because of the physical symptoms associated with rabies; it is therefore a physiological condition, rather than a psychological condition.
Rabies is a potentially fatal viral infection of the brain and nerves. It can be spread through the bite or scratch of an infected animal. It affects warm-blooded animals (commonly dogs, bats, foxes and humans). The rabies virus often stays dormant for between one and three months, before beginning to attack the central nervous system and symptoms begin to manifest, such as aggression or abnormal behaviour, fluctuating consciousness, frothing at the mouth and hydrophobia. Once this happens, treatment is ineffective, and death is almost inevitable.
Although rabies occurs in a number of warm-blooded animals, hydrophobia is a symptom that primarily occurs in humans. Hydrophobia develops during the advanced stages of rabies. It most frequently develops when a person has furious rabies – a type of rabies that results in inflammation of the brain, known as encephalitis. Furious rabies is the most common type of rabies, occurring in 80% of cases. In furious rabies, encephalitis destroys the nerve cells in the brainstem that control a person’s breathing. This can then lead to pharyngeal spasms, which are constrictions in the tube that connects your nose and throat to your oesophagus. The spasms can make it extremely difficult to swallow and can be triggered or worsened by drinking water.
A rabies-based phobia of water is characterised by physical symptoms that can result in difficulties swallowing or pain when swallowing. These painful and involuntary throat spasms can result in extreme fear, dread or panic when the person sees, feels, tastes or hears water. The anticipation of pain and the inability to swallow will likely cause the person to refuse to drink water, no matter how thirsty they are or how vital it is to their survival.
Because water is crucial to our health and survival, a fear of water can be extremely detrimental to your health, your well-being and your quality of life. Humans can only survive for approximately three days without water. However, because someone experiencing hydrophobia also has the rabies virus, their body is already likely to be weakened, meaning their survival time will be lower.
How does hydrophobia differ from aquaphobia?
Hydrophobia differs from aquaphobia because aquaphobia is a true phobia of water that is not connected to rabies and usually develops following a traumatic experience involving water. Aquaphobia is a type of specific phobia that is characterised by an extreme, irrational and overwhelming fear of water. Someone with aquaphobia will likely experience severe fear, anxiety or panic when faced with water.
They will also likely experience:
- Feelings of intense fear, panic or anxiety that are difficult to manage.
- Fear or anxiety that is out of proportion to the true risk.
- A fear of water that lasts for at least six months.
- Avoidance behaviours to prevent encounters with water.
- A fear of water that interferes with their day-to-day life, overall well-being or sense of safety.
Aquaphobia is an irrational fear of water that results in negative psychological and behavioural responses. However, unlike aquaphobia, which is a psychological condition connected to anxiety disorder, hydrophobia is a physical condition connected to the rabies virus. Hydrophobia is a clinical characteristic of rabies and is so closely connected with rabies that the rabies virus was historically referred to as hydrophobia. It occurs as a result of the physical effect the rabies infection has on your central nervous system.
Although aquaphobia and hydrophobia may share some similar signs and symptoms, they are both very different medical conditions that doctors can easily differentiate between. They both have different causes, prognoses and treatments.
How common is hydrophobia?
Hydrophobia rarely occurs in the UK, where cases of rabies are very low. Rabies has not been identified in animals in the UK, except for in a very small number of wild bats. However, cases do occur more frequently in other parts of the world, particularly in Asia, Africa, Central America and South America. The most concentrated cases of rabies occur in India, with 20,000 people dying from rabies every year, predominantly as a result of bites from stray, infected dogs. Approximately 59,000 rabies-related deaths occur every year worldwide.
Only 25 cases of hydrophobia, and therefore severe rabies that results in death, have occurred in the UK in the last 75 years. All of these cases were imported, meaning the individual caught the infection abroad and travelled back to the UK with it. There has only been one recorded case of someone contracting rabies in the UK and this occurred because of contact with an infected bat.
Who is at risk of hydrophobia?
Because rabies is extremely rare in the UK, people who live in the UK are considered to be at extremely low risk of hydrophobia. The majority of cases of hydrophobia and rabies occur in the continents of Asia and Africa.
Children are at greater risk than adults of contracting rabies, primarily because they are more likely to be bitten by dogs and other animals and are more likely to receive multiple bites and for the bites to puncture their skin. Children may also be more at risk because they may be unable to tell you or may forget if they receive a small, non-painful bite or scratch from an animal. This means that the rabies virus is more likely to progress to the stage in which hydrophobia develops.
Some people who are at higher risk of contracting hydrophobia are:
- Someone who lives or travels in areas where rabies is common.
- Someone who does a lot of outdoor activities that could put them in contact with animals that have rabies.
- Someone who lives in or travels to areas without quick access to healthcare.
- Someone who handles imported animals (for example, at an animal quarantine centre).
- Someone who works with or has contact with animals who are infected with the virus.
- Someone who works with or has contact with stray animals or injured or ill animals, particularly in countries with higher incidences of rabies.
- Someone who has had contact with an animal that is acting strangely.
- Someone who has had contact with a dead animal.
- Someone who regularly handles bats.
- Someone who has been bitten by a bat or had close contact with a dead bat.
- Someone who works at a laboratory handling rabies samples, particularly if effective protection measures are not in place.
If you were bitten or scratched by an animal or there is any possibility that you have come into contact with the rabies virus, particularly in the last three months, there is a possibility that the virus is active in your body and symptoms of rabies will develop, including hydrophobia.
The incubation period for rabies can range anywhere from five days to three months. In some cases, it is possible for you to contract rabies without showing symptoms for several years. The longest recorded period of dormancy is seven years. Approximately 1%-3% of recorded rabies cases have an incubation period that is longer than six months. If you had contact with an animal that potentially had rabies and you did not seek treatment, you may begin to experience symptoms that are consistent with rabies, including hydrophobia.
Who causes hydrophobia?
Hydrophobia is triggered during the advanced stages of furious rabies. It occurs after rabies spreads from the initial wound to the central nervous system and brain. The rabies virus is most commonly spread by a bite or scratch from an infected animal. It can also be spread if an infected animal licks an open wound or its saliva gets into your eyes or mouth, for example, if they spit in your face or lick inside your mouth.
Rabies is most commonly found in warm-blooded animals such as:
Rabies doesn’t spread between people, nor does it spread through unbroken skin. The only recorded cases of rabies spreading between humans were as a result of infected donor organs, although this is extraordinarily rare and has never occurred in the UK.
Once the rabies virus enters your body, it spreads into the central nervous system, the brain and the nerve endings. The virus then spreads into the salivary glands and your organs, including your lungs and kidneys.
Not everyone who is infected with rabies will develop hydrophobia, as hydrophobia is a symptom of the virus that only develops during the later stages of infection. If you receive effective treatment that successfully treats the infection, you shouldn’t develop hydrophobia.
Hydrophobia usually develops during the excitation phase of rabies, which is the stage characterised by hyperactivity, unusual or excitable behaviour and aggression.
What are the symptoms of hydrophobia?
Because hydrophobia is connected to the rabies virus, it is often present in conjunction with other common symptoms of rabies, such as:
- Agitation, aggression or confusion.
- A modified mental state.
- Difficulties breathing.
- Visual or auditory hallucinations (such as seeing or hearing something that no one else can).
- Muscle spasms.
- Producing excessive saliva (hypersalivation), frothing at the mouth or drooling.
- Fluctuating consciousness (going in and out of consciousness).
The rabies virus flourishes in saliva and swallowing actually reduces the spread of the virus. One of the main symptoms of rabies is therefore connected to the virus’s desire to spread. Rabies alters saliva production, causing your body to produce more saliva (this is why a frothing mouth or drooling is a commonly recognised sign of rabies).
Hydrophobia then develops to prevent the individual from swallowing the excess saliva. Painful spasms prevent swallowing and cause the individual to appear to fear or refuse water. The excess saliva they produce cannot be swallowed or washed down by drinking water, so it stays in their mouth or is spread to their surroundings, increasing the likelihood that the rabies virus will spread.
Someone with hydrophobia may also experience symptoms of aerophobia, an extreme fear of fresh air. This is because breathing air can result in the same pain or discomfort caused by hydrophobia.
How is hydrophobia diagnosed?
If you think you or someone else might be experiencing hydrophobia, particularly if you have any concerning symptoms, you should seek medical help immediately. Because hydrophobia is classed as an emergency, you should go to your local hospital or call 999 immediately. Ensure the ambulance or hospital is informed in advance that you are possibly experiencing hydrophobia so that they can prepare your care in advance and ensure that both you and other people are protected.
Even if you aren’t experiencing any hydrophobia symptoms but you have recently (in the last three months) been bitten or scratched by a warm-blooded animal, such as a dog, a fox, a racoon or a bat, it is still recommended that you visit your nearest hospital or medical centre or your GP as soon as possible, even if the bite or scratch occurred in another country. This is because post-exposure treatment can be extremely effective and prevent rabies from progressing to the stage where hydrophobia develops.
Sometimes, people who have been bitten or scratched by an animal don’t seek medical help as they think they may be catastrophising and that the chances of them actually contracting rabies are very low. However, you should always seek medical help, particularly if you were bitten or scratched by a high-risk animal or in a high-risk area.
Rabies is diagnosed using a direct fluorescent antibody (DFA) test. The test detects antigens of the rabies virus in your brain tissue.
Other diagnostic tests that can be used include:
- A skin biopsy – A small sample of your skin will be removed and examined to see if the virus is present.
- A saliva test – A sample of your saliva will be taken and examined to see if the virus is present.
- A lumbar puncture – A small sample of cerebrospinal fluid (CSF) is removed using a needle and checked for rabies antibodies.
- A blood test – A blood sample will be taken and checked for rabies antibodies.
However, in some cases, these antibodies do not occur until the later stages of rabies. Although these would be effective in diagnosing rabies once a person is exhibiting symptoms of hydrophobia, they may not be effective in the beginning stages of infection. In the majority of cases of suspected rabies, treatment will be administered before a diagnosis is confirmed. However, this will be judged on a case-by-case basis, for example, if you were bitten by a pet dog in the UK, rabies is extremely unlikely. On the other hand, if you were bitten by a stray dog in India, rabies is much more likely.
How is hydrophobia treated?
The treatment for rabies depends on whether you have started to show any signs or symptoms of infection. By the time the rabies virus progresses enough to cause hydrophobia, it is almost always fatal, and treatment is likely to be ineffective. A person or animal who contracts furious rabies will likely die within six days of showing symptoms and within a few days of showing symptoms of hydrophobia.
However, if the infection is treated quickly, ideally on the day of infection, the individual can have a good prognosis. Unfortunately, rabies has an incubation period of one to three months, meaning that by the time someone shows symptoms, the disease may have progressed too far, and treatment will be ineffective.
If you have recently been bitten and potentially exposed to rabies, your treatment may include:
- Cleaning and disinfecting the area.
- Four doses of the rabies vaccine over the course of a month if you haven’t been vaccinated or two doses if you have been vaccinated.
- Immunoglobin (most likely by injection) to the bitten or scratched area to provide immediate antibodies and short-term protection if you cannot immediately get the vaccine or before the vaccine begins to work.
The infection can be treated with a combination of the rabies vaccine and rabies immunoglobin, which help you to produce the antibodies that are required to fight the rabies virus. However, if treatment is not administered until the symptoms of hydrophobia have already manifested, it is highly unlikely that the treatment will be effective. It is therefore imperative that medical treatment is sought as soon as an animal bite occurs.
Once physiological and neurological symptoms of rabies manifest, such as hydrophobia, treatment will likely be ineffective and instead the individual will be given treatments to make them comfortable and protect them and other people. Once a person has developed hydrophobia, this means their brain and nerves have become infected. The blood-brain barrier (BBB), which is the network of blood vessels and tissue that prevents harmful substances from entering the brain but allows substances such as water, oxygen and antibodies into the brain, locks down. The BBB prevents anything from entering the brain, including antibodies and antiviral drugs. This makes rabies, and hydrophobia, impossible to treat and enables the virus to continue attacking the central nervous system.
If someone is showing symptoms of hydrophobia and a diagnosis of rabies is confirmed or highly suspected, treatment will focus on making them as comfortable as possible, rather than curing the infection. In many cases, a diagnosis of rabies is considered to be established if a person has hydrophobia and/or is showing other symptoms. In this situation, doctors will try to make them as comfortable as possible by using sedatives or tranquillisers. Because an individual with hydrophobia cannot drink water, they may be given intravenous fluids via a drip. Once symptoms of hydrophobia have developed, death usually occurs within a few days, usually because of cardio-respiratory arrest.