Amebiasis is a parasitic disease of worldwide public health importance. Approximately 100,000 people throughout the world die annually from amebiasis infection, making this infection the second leading cause of death from parasitic diseases. It is caused by a one-celled parasite, Entamoeba histolytica. Amebiasis occurs mainly in developing countries having poor sanitary conditions and is more severe among the young and old and in patients receiving corticosteroids. In the United States, it is found in immigrants, travelers to developing countries, people living in institutions with poor sanitary conditions and male homosexuals.
Cause of amebiasis
Amebiasis is a protozoan infection of the lower GI tract. The causal parasite, E. histolytica, exists in two forms: the trophozoite and the cyst. Infection ensues with the ingestion of viable cysts in fecally contaminated food and water. The cyst passes through the stomach and small intestine and excystation occurs in the bowel lumen. Sexual transmission of E. histolytica results in enteric infection with possible dissemination of venereal infection in males and females.
Symptoms of amebiasis
Most people (90%) infected with E. histolytica remain asymptomatic, while a varied array of clinical syndromes ranging from diarrhea, dysentery and colitis to abscesses of the liver, spleen and brain develop in the remaining 10%.
The most common symptoms of infection include:
- Intermittent diarrhea and constipation
- Flatulence
- Cramping
- Abdominal pain
- Stools may contain mucus and blood
The incubation period for infection is 7-28 days.
Incidence and prevalence of E. histolytica infection
The prevalence of infection with E. histolytica worldwide is estimated to be 50 million cases each year, with about 10 times as many cases of E. dispar, a non-pathogenic organism recently discovered to be genetically distinct from the pathogenic E. histolytica. Prevalence is highest in Central and South America, Africa and Asia.
In the United States and other developed countries, the infection is rare, but when found tends to be more common among persons with a history of travel or residence in developing countries. In 1993, approximately 3,000 cases were recorded in the US, with most of the cases arising in immigrants from Mexico, Central and South America (33%), and from Asia or the Pacific Islands (17%).
Diagnosis of amebiasis
The diagnosis of amebiasis is based on detection of cysts or trophozoites in the feces. Methods for diagnosis include microscopy; stool culture; antigen detection; serology; and molecular probes, such as polymerase chain reaction. The use of diagnostic tools with high diagnostic efficacy is important to separate E. histolytica (pathogenic) from Entamoeba dispar (nonpathogenic).
Prior to more sensitive tests becoming available, E. histolytica diagnosis had been based primarily on examinations of stool for ova and parasites which resulted in not differentiating the commonly occurring, nonpathogenic species, E. dispar.
Treatment of amebiasis
Tindamax® (tinidazole) is a well-tolerated, highly effective treatment for amebiasis. Tinidazole's average cure rates are 92% for intestinal amebiasis and 93% for amebic liver abscess.1,8-16
Cure rates with Tindamax® in GI-related infections1
† 8 randomized, comparative studies. Cure rates ranged from 80%-100%.
‡ 4 randomized, comparative studies. Cure rates ranged from 86%-93%.
§ 7 randomized, comparative studies; 4 studies utilized at least 3 days of tinidazole. Cure rates ranged from 81%-100%.
Important Safety Information
WARNING: POTENTIAL RISK FOR CARCINOGENICITY
Carcinogenicity has been seen in mice and rats treated chronically with metronidazole, another nitroimidazole agent. Although such data have not been reported for tinidazole, the two drugs are structurally related and have similar biologic effects. Its use should be reserved for the conditions described in INDICATIONS AND USAGE.
Tindamax® is a prescription antibiotic used to treat certain infections caused by bacteria and parasites. It is approved for treating trichomoniasis, also known as "trich," and bacterial vaginosis, or "BV" (in non-pregnant, adult women). It is also approved for treating giardiasis, also known as "giardia," amebiasis, and amebic liver abscess in patients age 3 and older.
Important Safety Information
Tindamax® is not for everyone. You should not take Tindamax® if you are in the first trimester of pregnancy. If you are nursing, Tindamax® can pass through your breast milk, so you should not take it unless you stop breastfeeding during your prescription and for 3 days after your last dose.
Tindamax® can lead to a temporary reduction in your white blood cells, so if you have been diagnosed with a blood disorder, talk to your doctor before starting a prescription.
Do not take Tindamax® if you have a history of sensitivity to tinidazole or related drugs in the nitroimidazole family. Reactions can range from mild itching, hives, or fever to Stevens-Johnson syndrome, which is a rare, life-threatening skin condition.
Certain drugs may interact with Tindamax®, so always tell your doctor about the medications you're taking before you start a prescription.
Take each dose of Tindamax® with food to lessen the risk of stomach upset and other GI side effects. Avoid any alcoholic beverages while taking Tindamax® and for 3 days afterward.
If you are undergoing hemodialysis while taking Tindamax® on the same day, consult your doctor for the appropriate dose of Tindamax®. An additional half-dose of Tindamax® at the end of dialysis may be recommended.
Antibacterial drugs, including Tindamax®, do not treat viral infections such as the common cold. When taking Tindamax® to treat a bacterial infection, it is very common to feel better early in your prescription; however, you should keep taking the medication as directed and for as long as directed by your doctor. Skipping doses or not taking all of your medication can make Tindamax® less effective. It can also allow the bacteria to build up resistance to the drug, so that it won't be treatable with Tindamax® or similar drugs in the future.
The most common side effects of Tindamax® are a metallic or bitter taste, nausea, weakness, fatigue, discomfort, indigestion, cramps, vomiting, loss of appetite, headache, dizziness, and constipation.
Some patients taking Tindamax® may also develop a yeast infection, which can require treatment with an anti-fungal drug. Talk to your doctor if you notice any unusual symptoms.
Certain patients taking Tindamax® have experienced seizures or nerve problems, with symptoms such as numbness or tingling of the hands or feet. Other side effects included vertigo, unsteady movements, insomnia, or drowsiness. Stop taking Tindamax® if you develop any abnormal symptoms.
Tinidazole, the key ingredient in Tindamax®, is related to a drug called metronidazole, which has been linked to cancer in lab rats and mice that received the drug over long periods of time. Although these effects have not been reported for tinidazole, the two drugs are chemically related and have similar effects on the body. Therefore, Tindamax® should only be used to treat infections it has been approved to treat.
To report negative side effects, contact Mission Pharmacal Company at 1-800-298-1087 or the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
- Data on file. Mission Pharmacal Company.
