Amebiasis
(Entamoeba histolytica infection or E. histolytica infection)
| Amebiasis is caused by the protozoan parasite. |
Protozoan infections include amebiasis, toxoplasmosis, and trypanosomiasis. Protozoa can produce malaria, amebiasis, leishmaniasis and trypanosomiasis. There is no immunization to protect against gastrointestinal amebiasis.
The parasite that causes sleeping sickness is called the trypanosome, a vector-borne parasitic disease. Trypanosomes manage to evade the immune system by modifying their surface membrane, a process known as antigenic variation. The trypanosome can express thousands of variants, multiplying with each new surface change. Gradually, the immune defence mechanisms and the patient's resistance are exhausted. As the parasite develops in the lymph and blood of the patient, the initial symptoms become more pronounced and other manifestations such as anaemia, cardiovascular and endocrine disorders, abortion, oedema and kidney disorders appear. Trypanosomiasis, a sleeping sickness, is a serious parasitic disease marked by extreme tiredness that is always fatal without treatment. If left untreated, the illness becomes worse, and death occurs within several weeks to months.
In advanced stages of disease, the parasite invades the central nervous system. The patient's behaviour changes; they can no longer concentrate and become indifferent to their environment. Sudden and unpredictable mood changes become increasingly frequent, giving rise to lethargy with bouts of aggressiveness. Patients are overcome by such extreme torpor that eating, speaking, walking or even opening the eyes call for an unsurmountable effort. At night they suffer insomnia and during the day are exhausted by periods of sleep-like unconsciousness. Finally, patients fall into a deep sleep from which they may not recover.
American trypanosomiasis (Chagas' disease) is caused by a protozoan parasite that is usually transmitted by contact with the feces of an infected reduviid bug. Transmission may also occur through blood transfusion or via transplacental infection. Acute infection may be asymptomatic or accompanied by a fever with inflammation of the heart muscle or the lining of the brain or spinal cord. Tourists are at greatest risk for this illness.
Mexico is a hotbed for amebiasis; In Mexico City the incidence of amebiasis is exceedingly high and a large percentage of the people who visit there
Clinical Presentation
A local area of swelling may occur at the site of inoculation. Acute infection can be asymptomatic or accompanied by a febrile illness with meningoencephalitis or myocarditis, or both. Manifestations of chronic infection include cardiomyopathy and intestinal "mega" syndromes (e.g., megaesophagus and megacolon).
Diagnosis of amebiasis can be very difficult. One problem is that other parasites and cells can look very similar to E. histolytica when seen under a microscope. Therefore, sometimes people
are told that they are infected with E. histolytica even though they are not. Entamoeba histolytica and another amoeba, Entamoeba dispar, which is about 10 times more common, look the same when seen under a microscope. Unlike infection with E. histolytica, which sometimes makes people sick, infection with E. dispar never makes people sick and therefore does not need
to be treated.
Illness occurs usually 1 to 4 weeks following contact but sometimes more quickly or more slowly.
International Travel Medicine Clinic - Other Infectious Diseases
Amebic (cysts) dysentery is a severe form of amebiasis associated with stomach pain, bloody stools, and fever. Rarely, E. histolytica invades the liver and forms an abscess. Even less commonly, it spreads to other parts of the body, such as the lungs or brain.
In the Canada and the United States, amebiasis is most often found in immigrants from developing countries. It also is found in people who have traveled to (or who have come into contact with) developing countries and in people who live in institutions that have poor sanitary conditions which pose health issues for travelers.
Sleeping sickness (trypanosomiasis), neurological
Protozoal causes associated with meningitis include toxoplasmosis and trypanosomiasis
http://www.oocities.org/target_index/AmebiasisClues.HTMhttp://www.medscape.com/viewarticle/491437_2