West Nile virus frightens many parents because it can cause a type of infection called encephalitis.
What is encephalitis?
Meningitis is primarily an inflammation of the lining of the brain and spinal cord, and sometimes of the brain itself. Encephalitis is primarily an inflammation of the brain.
Most of the time, the inflammation is caused by viral infections. West Nile virus rapidly spread across the United States at the turn of the 21st century as a cause of encephalitis, but enteroviruses are far and away the most common cause. Arboviruses and herpes are also common. West Nile virus is an arbovirus.
Measles, mumps, chickenpox, rubella, CMV, EBV, and rabies are other noteworthy causes. For example, before vaccination, mumps encephalitis was a common cause of deafness.
Most children with viral encephalitis recover completely with no complications, but sometimes the results are devastating. Some viruses, such as herpes, tend to cause more severe illness than others.
Who gets it?
Anyone can get encephalitis. It tends to be more common in the summer and fall. Some types are found in those who are bitten by infected mosquitoes or other insects. Some types are found in those who get infected stool particles in their mouths. Some types are found in those who just spend time in the same room as someone infected with the virus.
What are the symptoms?
The symptoms can vary quite a bit, from those of a very mild illness to coma or sudden death. A severe headache is usually the central symptom. Often there is sensitivity to light. There may be a fever, vomiting, fatigue, and/or irritability. With some viruses there is a characteristic rash. Neck pain, back pain, and leg pain are common.
In some, there are severe seizures, hallucinations, and loss of bowel or bladder control. Even these children may recover completely with no lasting problems.
Is it contagious?
Some types of encephalitis, such as that caused by West Nile virus, do not spread easily from person to person, although they can be spread by transfusion or organ transplant. Other encephalitis viruses, such as measles, spread very easily among unvaccinated people.
How long does it last?
These infections may be brief or prolonged. Children may recover completely or suffer lifelong consequences.
How is it diagnosed?
The diagnosis is suspected based on the history and physical examination. Lab tests of the spinal fluid or blood may be helpful. EEGs or imaging studies of the brain may help in making the diagnosis and evaluating the severity of the disease. Sometimes specific viral studies are helpful.
How is it treated?
Encephalitis may be so mild as to require only rest, fluids, and something for the headache — or it may require intensive care and full life-support.
Some types, such as that caused by herpes, require specific antiviral therapy.
How can it be prevented?
Measles, mumps, rubella, chickenpox, and even rabies encephalitis may be prevented by appropriately timed vaccines. Other types of encephalitis may be prevented by avoiding mosquito bites.
Fecal-oral transmission precautions are the best way to prevent enteroviral infections, the most common cause of encephalitis in places where vaccines are commonly used. Careful hand washing before eating and after toileting or diaper changes is essential. This is an important hygiene lesson to teach our children.
Meningoencephalitis, Viral encephalitis, West Nile encephalitis.