Encephalitis is an inflammation of the brain. The most common cause is a virus, but it can also be caused by bacteria and fungi. The condition is called primary encephalitis if the virus attacks the brain directly, and secondary if the virus first attacked another part of the body and spread to the brain. The virus can also attack the spinal cord and the meninges. Meninges are the membranes that enclose the brain.
Encephalitis strikes both sexes and can happen at any age, but it most often attacks the very old, the very young and people with weakened immune systems. People who live in areas that are heavily infested by mosquitoes are also at higher risk. Enccephalitis can be caused by different viruses, and in the United States the most common virus that causes the disease is the herpes simplex virus. People can also get the disease through arboviruses spread through ticks and mosquitoes. The viruses that cause measles, mumps and chickenpox can also be causes of encephalitis. In extremely rare cases, the virus that causes rabies can lead to the disease.
Clearly, encephalitis can be a dangerous disease, but deaths and complications such as coma and brain damage are rare. Diagnostic tools include imaging tests such as CT and MRI scans and tests of blood and spinal fluid. In some cases, the doctor will perform a brain biopsy, which takes a small piece of the patient’s brain and has it studied under a microscope.
Most people with encephalitis need to be hospitalized though a patient with a mild case may be asymptomatic or have such mild symptoms that they do not take notice of them. For other patients, their symptoms last three to five days. Otherwise healthy people who get encephalitis usually recover completely, but this can take some months.
1. Muscle Pain
A person with encephalitis may feel pain or aches in their muscles. This is also called myalgia. In the case of encephalitis, the pain and aches are systemic, which means they occur throughout the patient’s body, including muscles in the head, which can lead to headache, and in the neck, shoulders, arms and legs. This is often what happens when the muscle pain is the result of an infection and not a result of overuse. In some patients, the pain is mild enough to be ignored while in others it is excruciating.
2. Body Fatigue
Fatigue is another symptom that is often caused by disease, including encephalitis. It is different from tiredness or drowsiness, which makes a person want to go to sleep. When a person feels bodily fatigue they feel an unremitting sense of tiredness. The fatigue makes it difficult for the person to start an activity in the first place and makes it difficult to finish it once it has started. They also have trouble concentrating and have problems with their memory. Added to the other symptoms and signs of encephalitis, body fatigue can leave a patient truly debilitated.
3. Fever
Fever is often the body’s reaction to an infection. Fever happens because the hypothalamus resets the body temperature when the person is sick. A baby who is less than three months old is feverish if their rectal temperature is 100.4 degrees Fahrenheit or higher. Such a temperature is considered a medical emergency, and the baby needs to be seen by a doctor right away. This also true of child who has a fever higher than 100 degrees F. Babies and young children who have such high temperatures are at risk for seizures. The other signs and symptoms that accompany encephalitis will most likely prompt a parent to take their child to the hospital anyway. An adult is considered to be feverish if they have a temperature of 100 degrees F when measured by an oral thermometer.
4. Loss of Appetite
People who are sick often suffer from loss of appetite. Some researchers believe that this lack of appetite ramps up a process called autophagy, which is when old, damaged cells and their debris are recycled to be reused by the body. Autophagy is speeded up when the body doesn’t receive its usual nutrients. Moreover, the body not only rids itself of debris from its old cells more quickly, but gets rid of pathogens as well.
5. Nausea
Nausea is the sensation that a person is about to throw up. It gets its name from the seasickness many people experience when they are on a boat. Nausea works much like the loss of appetite when a person has an infection. In this case, the person is not just uninterested in eating but is actually sickened by the idea. This in turn helps the cells and the immune system remove debris as well as viruses and bacteria from the system. Nausea can be bad enough for the person to not want to move much at all, which helps them to rest.
6. Irritability
Irritability is another common symptom when people are sick for any reason. People who are usually competent when they are healthy dislike being laid low and may react by being cranky. This is even true of young children. In the case of encephalitis, the fact that the brain is actually under attack can cause sometimes severe changes in personality or behavior. The patient may even become confused. Though it is not common, encephalitis can cause damage to the brain in a way that affects the personality. Fortunately, there are types of behavioral therapy that can help.
7. Headache
The headache of encephalitis can be mild or very severe or crippling. Since the brain has no pain receptors, pain is actually felt in the muscles, blood vessels and nerves in the person’s head and neck. The pain comes as these structures tighten up, dilate or respond to pressure. The headache is caused when the body releases cytokines, proteins which are part of the immune system and released to fight the virus that has cause the illness. They include lymphokines, which are remade by white blood cells called lymphocytes; monokines, which are made by blood cells called monocytes and interleukin, which are made by white blood cells called leukocytes and regulate the action of other types of leukocytes. Cytokines also influence the cells that secrete them, cells that are nearby and cells that are distant.
8. Light Sensitivity
This symptom is when light hurts the eyes of the patient with encephalitis. It is also called photophobia. Scientists are still not certain what causes light sensitivity, but many believe it has something to do with the trigeminal nerve, or the fifth cranial nerve. This large nerve regulates the sensations that come into the eye, the orbit around the eye, the patient’s head and the meninges. It may be that the inflammation of the meninges can cause the patient not to be able to tolerate too much light.
