Caused by protozoa, a class of single-cell parasites, protozoal infections are common in rural areas of underdeveloped countries in Africa, Asia, and South America. They are relatively rare in the United States and other industrialized nations, but do occur among Western travelers to Third World countries.
Such infections include:
Amebiasis, which can infect the skin, intestines, liver, lungs, and chest cavity, it is caused by Entamoeba histolytica.
Babesiosis, an infection of the red blood cells that can lead to hemolytic anemia; it is caused by Babesia organisms that are transmitted by ticks.
Cryptosporidiosis, an intestinal infection that is usually self limiting, but can be life-threatening to an AIDS patient; its cause is Cryptosporidium.
Giardiasis, an intestinal infection that often produces diarrhea; it is caused by Ciardia lomhlia, an organism contracted by drinking water contaminated with animal and human waste.
Leishmaniasis, an infection of the skin, mucous membranes, or internal organs, depending on the cause; it is brought on by any of several Leish-mania protozoa carried by sand flies.
Kala-Azar, which produces recurrent fever and severe weight loss, and cutaneous leishmaniasis, which causes boils and skin ulcers, are among the more common types of this illness.
Trypanosomiasis, or African sleeping sickness, an often fatal disease; its cause is Trypanosoma, which is spread by tsetse flies. A South American variation, called Chagas disease, is spread by assassin, or kissing reduviid, bugs and is generally milder.
Diagnostic Studies and Procedures
Characteristic symptoms and recent travel to a developing country may lead a doctor to suspect a protozoal infection, but identifying the organism is often difficult. Analyses of blood, urine, stool, and perhaps stomach juices and other body fluids are needed.
Treatment will depend on the infecting organism. Metronidazole (Flagyl) is usually the first choice for an uncomplicated case of amebiasis or giardiasis. This drug, which is given orally or by injection for 5 to 10 days, often causes nausea, loss of appetite, abdominal pain, and dark urine. It is important to abstain from alcohol while taking it.
Giardiasis may also be treated with quinacrine (Atabrine). a drug used to treat malaria. Babesiosis is usually treated with intravenous clindamycin, an antibiotic, and quinine, an antimalaria drug.
Cryptosporidiosis can be difficult to treat, especially if a patients immune system is weakened by other diseases or drugs. Sometimes, strenguhening the immune system by stopping immunosuppressive drugs and correcting any nutritional deficiencies aids healing.
African trypanosomiasis is treated with intravenous eflornithine (DFMO), an antiprotozoal drug. An alternative is melarsoprol, which is more potent but also more dangerous because it contains arsenic and can damage the kidneys. Suramin and pentamidine, an antiprotozoal drug, may be prescribed to treat leishmaniasis.
Other treatments are directed to controlling symptoms and manifestations of the disease, and may include blood transfusions and intravenous fluids.
No alternative therapy can cure a protozoal infection, but when used alongside the appropriate medical treatment, some can alleviate symptoms.
Herbal Medicine. Meadowsweet is commonly recommended to control all types of diarrhea. For acute attacks, herbalists prescribe a tea made with a mixture of equal parts meadowsweet, American cranesbill, and bayberry, to be consumed hourly until the symptoms subside, and then before meals until the digestive system returns to normal. A glass of unsweetened black currant juice three times a day is an alternative remedy. Other herbs used to treat diarrhea include teas made from raspberry leaves or chamomile.
A poultice of echinacea root may be used to lower a fever. Other treatments for fever include a lea made from a mixture of hyssop, licorice root, thyme, and yarrow, and tea made with blackthorn, fenugreek seed, feverfew, ginger, poke root, or echinacea.
Homeopathy. Practitioners use podophyllum, several times a day, to treat severe chronic diarrhea.
Naturopathy and Nutrition Therapy. Extra fluids are advised, especially distilled water and vegetable juices, to protect against dehydration caused by diarrhea and fever. In severe cases, rehydration fluids or Gatorade may be needed to restore the electrolyte balance. As the diarrhea subsides, a patient can resume solid foods with the BRAT diet of bananas, rice, applesauce, and toast. Coffee, alcohol, milk, and spicy or fatty foods should be avoided.
Prevention is the best approach. If you are spending time outdoors or sleeping in infested places, wear clothing with long sleeves and pants legs, and cover your sleeping area with mosquito netting. Drink, cook with, and brush teeth with bottled or boiled water, wash your hands often, and always before meals.
Other Causes of Protozoal Infections
Other protozoal infections that occur in the United States include toxoplasmosis, which is transmitted by eating undercooked meat or by contact with cat feces; trichinosis, from eating infected pork; and trichomoniasis, a sexually transmitted disease.