American Medical Association Family Medical Guide - American Medical Association [653]
Symptoms
Symptoms of a West Nile virus infection usually develop from 3 to 14 days after the infecting mosquito bite. A mild case, called West Nile fever, is characterized by flulike symptoms such as fever, headache, body aches, and, sometimes, a rash on the trunk and swollen lymph nodes. The symptoms in mild cases usually last only a few days and don’t cause any long-term health effects. Infection with West Nile virus may provide lifelong immunity to the virus.
The symptoms of more severe infections—West Nile encephalitis (inflammation of the brain), meningitis (inflammation of the membranes surrounding the brain and spinal cord), and meningoencephalitis (inflammation of the brain and the membrane surrounding it)—include headache, a high fever, a stiff neck, disorientation, muscle weakness, tremors, seizures, coma, and paralysis. These symptoms can last several weeks and their effects on the brain can be permanent or fatal.
Diagnosis
To diagnose a West Nile virus infection, a doctor will take a detailed health history to evaluate a person’s risk of infection, such as being in an area where the virus has been detected. If your doctor thinks you may be infected or if you have symptoms, he or she will take a sample of blood and send it to a laboratory for microscopic examination to detect the virus.
Treatment
There is no specific treatment for a West Nile virus infection. Mild cases generally clear up on their own. For severe infections, people are usually hospitalized and given intravenous fluids and antibiotics (to prevent or treat secondary bacterial infections such as pneumonia). If breathing is affected, a person may need to use a ventilator to temporarily assist breathing.
Babesiosis
Babesiosis is a rare, potentially life-threatening disease caused by the Babesia microti parasite, which is spread to people through the bites of infected ticks that live on animals such as deer and mice. Babesiosis also can be transmitted through blood transfusions. The parasite that causes babesiosis attacks red blood cells.
Babesiosis can be mild or severe. Most people who are infected do not become sick. However, older people and people who have an impaired immune system or who have had their spleen removed (splenectomy) are at increased risk of developing a severe infection. If not treated, babesiosis can cause extremely low blood pressure, hemolytic anemia (see page 616), liver problems, and kidney failure in high-risk people.
Although babesiosis usually occurs in the coastal areas of the northeastern United States, cases have been reported on the West Coast and in the Midwest. The tick that carries Lyme disease (see page 942) and ehrlichiosis (see below) can also carry babesiosis, and a person can be infected with a combination of the diseases at the same time. If you find a tick embedded in your skin, remove it as soon as possible (see page 943).
Symptoms
Symptoms of infection with babesiosis may develop from 1 week to a month after a bite by an infected tick. Symptoms can include fatigue and a general sense of feeling ill. Later symptoms may include headache, fever, muscle and joint aches, and drenching sweats.
Diagnosis and Treatment
To diagnose babesiosis, your doctor will take a detailed health history and perform blood tests to check for antibodies (proteins the body produces to fight the parasite) or for the parasite itself. The disease can be difficult to diagnose in older people and in people who have other health problems.
Although most people do not need treatment for an infection with babesiosis, a doctor may prescribe a combination of antiparasitic medications for those at risk of severe illness or complications.
Ehrlichiosis
Ehrlichiosis is an infection caused by ehrlichia bacteria, which can be transmitted to people in tick bites. The infection has two forms—monocytic and granulocytic. Human monocytic ehrlichiosis is caused by a type of ehrlichia bacterium that attacks the infection-fighting white blood cells called monocytes. The bacterium that causes the granulocytic