American Medical Association Family Medical Guide - American Medical Association [649]
Treatment
To treat chigger bites, your doctor may prescribe medication such as antihistamines to relieve itching, corticosteroid creams to reduce irritation and allergic reactions, or antibacterials applied directly to the affected area to prevent bacterial infection.
Toxoplasmosis
Toxoplasmosis is a rare infection caused by the parasite Toxoplasma gondii. Found throughout the world, the parasite can infect virtually all warm-blooded animals, including livestock, birds, household pets, and humans, but cats are the major host and source of infection. Eating raw or undercooked meat is a less common source of infection. In the United States, about one of five people has been exposed to the parasite that causes toxoplasmosis, but most people have no symptoms because their immune system keeps the infection in check. The parasite remains in an inactive state inside muscle or brain tissue and usually causes no health problems.
Two groups of people—pregnant women and people who have a weakened immune system—have especially important reasons for avoiding infection with the parasite. A pregnant woman who contracts toxoplasmosis has a 40 percent chance of passing the infection to her fetus, a serious condition called congenital toxoplasmosis, which affects one or two babies of every 1,000 born in the United States each year. In people who have a weakened immune system (such as from an HIV infection or cancer or from taking immune-suppressing drugs), toxoplasmosis can cause life-threatening symptoms affecting the central nervous system and brain.
Cats, both domestic and wild, are the only hosts that produce the oocyst, the sexually mature and most infectious (to humans) stage of the parasite’s life cycle. The parasite multiplies in the cat’s intestine, and the oocyst is excreted in the cat’s feces. Cats become infected when they eat contaminated rodents or birds, but infected cats have no symptoms.
Symptoms
Most healthy people who are infected with toxoplasmosis have no symptoms. Others experience swollen glands, muscle aches, and flulike symptoms that last for a few days to several weeks. Once you have been exposed to toxoplasmosis, you cannot get it again.
Women who develop toxoplasmosis more than 6 months before becoming pregnant are immune to the infection and cannot pass it on to their fetus. Women who contract toxoplasmosis during pregnancy have a higher-than-normal risk of having a miscarriage or stillbirth and can transmit the infection to the fetus. Infants born with congenital toxoplasmosis often appear normal at birth but develop symptoms such as blindness, deafness, seizures, and mental retardation months or even years later.
People who have a weakened immune system (such as those who are infected with HIV) cannot fight the infection and will experience headaches, confusion, fever, seizures, poor coordination, and nausea. Dormant toxoplasmosis infections can reactivate in people who have a weakened immune system, causing the same symptoms as those of a new infection.
Diagnosis
A blood test can detect the antibodies (infection-fighting proteins) that the body produces after infection by the toxoplasma parasite. If you plan to become pregnant, consider being tested for toxoplasmosis. If the test result is positive (meaning that you have been infected), there is no need to worry about passing the infection to a fetus during pregnancy. If the test result is negative, take precautions to avoid infection (see below). To find out whether a fetus is infected, doctors perform prenatal tests, including amniocentesis (see page 510) and an ultrasound scan (see page 509).
Treatment
Most people who are infected with toxoplasmosis need no treatment. Doctors treat infected people who have weakened immune systems with two antiparasitic drugs, pyrimethamine and sulfadiazine; pregnant women who have toxoplasmosis are treated with spiramycin. These drugs also lessen the severity of an infected infant’s symptoms both at birth and later in life.
Prevention
If you are pregnant or have a weakened