What Is Protozoa?

Protozoa are one of the three main classes of parasites that cause diseases in humans. They are single-celled organism, and can only be seen under a microscope. When they invade a human they are able to multiply easily, which causes them to be at a great advantage and puts humans at a disadvantage. This helps them survive in the human body and causes a serious infection even with the arrival of a single protozoon.

Infections caused by protozoa are contagious. Those protozoa that have inhabited the human intestine can be transmitted from one human to the other via the fecal-oral route, such as through sharing food the infected person has touched and through direct person to person contact. Protozoa living in the blood or tissue can be transmitted through a third source such as a mosquito. Infections are easily transmitted and persons carrying this parasite should avoid interactions with others, especially those with compromised and weakened immune systems.

There are four main groups of protozoa that cause infection in humans. They have been grouped according to how they move: the sarcodina (ameba), mastigophora (flagellates), ciliophora (ciliates) and the Sporozoa.

Protozoan Diseases

1. Amoebiasis

This disease is caused by the sarcodina group of protozoa. They secrete enzymes that are then absorbed by the tissue of the host. Amoebiasis is transmitted through contact with infected feces. Food and water contaminated by feces is the most common route of transmission, however, oral contact with fecal matter can also cause infection. Sometimes there are no visible symptoms but some common ones include loose stools with varying amounts of blood and an inflamed colon.

2. Giardiasis

This disease is also transmitted through oral contact of feces as the parasite is found in fecal matter. If hands are not properly washed after using the bathroom or changing a diaper, it is easy to come into contact with this parasite. Drinking water which has been contaminated by this parasite or even ingesting contaminated swimming water can cause giardiasis. Symptoms include mucusy stools, diarrhea, nausea, abdominal pain and upset stomach.

3. African Sleeping Sickness

African sleeping sickness is a disease caused by the protozoa, which are carried by the tsetse fly and are transmitted to humans through tsetse fly bites. This disease is fairly damaging to the human body and can cause serious illness. Symptoms of this disease include confusion, seizures, insomnia, personality changes, weight loss, slurred speech and trouble talking or walking.

4. Leishmaniasis

This disease is caused by the Leishmania parasite. These parasites are found mainly in southern Europe, the tropics and subtropics. The most common form of this disease being spread is through the bite of a sand fly, which carries the parasite. External leishmaniasis will affect the skin and internal leshmaniasis affects the inner organs such as the spleen and liver. Those parasites that affect the skin cause sores, which will enlarge and become deeper as the disease progresses without treatment. Internal infection will cause weight loss, organ enlargement, fever and extremely high or low blood levels.

5. Toxoplasmosis

Toxoplasmosis is caused by one of the most common parasites in the world, according to the Mayo Clinic. Many of the people infected by this disease do not have any symptoms. However, for those who have weak immune systems such as infants and people suffering from chronic illnesses, this parasite can cause serious illness. Infants who are born to mothers who carry the infection can experience complications at birth. Other symptoms include body aches, fatigue, fever, sore throat and swollen lymph nodes. Symptoms are very similar to flu like symptoms and this disease can sometimes be mistaken for the flu.

6. Malaria

Malaria is a very common disease in some countries and is spread through mosquito bites of mosquitoes that have been infected by one of the many different malaria-causing parasites. In the United States, there are more than 1300 cases of malaria reported. This is mainly reported by individuals travelling to or coming from the South Asian subcontinent or the sub-Saharan Africa who may be carrying the parasite. Malaria symptoms include headache, chills, tremors, aches and shaking.

7. Babesiosis

This disease is caused by the Babesia parasite that is transmitted through ticks. It can also be transmitted through blood transfusions of donors who carry the Babesia parasite. This parasite is common throughout the United States, in cities such as New England, New Jersey, New York, Wisconsin and Minnesota. Those individuals infected with the Babesia parasite may not experience any symptoms. However, common signs and symptoms include nausea, body aches, fatigue, fever, chills, weight loss and a decreased appetite. For those who are already suffering from health problems and those who have a compromised immune system, this disease can be life threatening and cause serious health problems.

8. Trichomoniasis

This disease is caused by the protozoan parasite, Trichomonas vaginalis. This disease is most commonly transmitted sexually. It is a dangerous parasite as it can also help along HIV transmission. Symptoms of this disease differ per gender. In woman, vaginitis may occur which will cause white discharge. Men may experience a burning while urinating. This disease is treatable with an antibiotic such as metronidazole.