[Biology Class Notes] on Protozoal Disease Pdf for Exam

Protozoa is a phylum or a grouping of phyla that consists of many unicellular eukaryotic organisms which belong to the kingdom Protista. Protozoa can be of several types such as amoebas, flagellates, ciliates, sporozoans, and lots more. Protozoal diseases are diseases that are caused by protozoal infections. Protozoans are responsible for various infections and diseases which affect different types of organisms including plants, animals, and some marine life. Protozoans also cause some deadly diseases in human beings. These organisms are mostly parasitic. They mostly thrive on the human host for their entire life cycle whereas some carry out the reproductive part in insects or other hosts.

Protozoal Infections 

Protozoal infections have an enormous impact on the health economic and social sectors mostly in the tropical and subtropical regions. Protozoan parasites that are infectious to human beings pose a significant threat to health. These protozoal infections claim almost 1.1 million lives annually. The diseases caused by protozoa are not only limited to humans but also affect plants and other organisms. Some of the most prevalent and deadly protozoan diseases in humans include malaria, African Sleeping sickness, Chagas disease, amoebic dysentery, Leishmaniasis, Toxoplasmosis, Giardiasis, and Cryptosporidiosis. The burden of human protozoan infections has been magnified by the lack of licensed and effective vaccines for some of the diseases these parasitic protozoans cause.

Protozoan Diseases in Humans 

Malaria is caused by a single-celled eukaryotic microorganism called protozoa. Specifically, the parasitic Plasmodium genus is responsible for this disease. Mainly Plasmodium falciparum and Plasmodium vivax are responsible for malaria in humans out of the six Plasmodium species. Malaria leads to significant morbidity and economic downfall. Pregnant women, children, and old-aged people are more prone to malaria. The symptoms of malaria include fever and flu-like sickness accompanied by shaking chills, muscle pain, headache, and tiredness. Nausea, vomiting, and diarrhoea may also occur alongside. Malaria may also cause anaemia and jaundice because of the heavy loss in the RBC count. The patient should be treated with proper antimalarial drugs such as Chloroquine, Doxycycline, and lots more.

African sleeping sickness is the other name of African trypanosomiasis. This disease is caused by the parasitic protozoan of the Trypanosoma genus. It has two forms namely West African and East African trypanosomiasis. These protozoal infectious diseases are caused by Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. Trypanosoma brucei gambiense accounts for about 95% of the cases. This parasitic protozoan causes a chronic infection which may emerge as a severe disease years later. Its symptoms include fever clubbed together with severe headaches, irritability, and extreme fatigue. Swollen lymph nodes and aching muscles and joints are also some of the common symptoms. Some typical neurological problems may occur if the disease has spread into the central nervous system.

Chagas disease is also known as American trypanosomiasis. It is an emerging health concern in Latin America. It is caused by infection with Trypanosoma cruzi.  Leishmaniasis is a group of complex diseases caused by different species of the Leishmania genus. There are different clinical forms of Leishmaniasis such as visceral leishmaniasis (VL), cutaneous leishmaniasis (CL), and mucocutaneous leishmaniasis (MCL). Giardiasis is a disease caused by a flagellated protozoa named Giardia. Toxoplasma gondii causes a protozoan infectious disease known as toxoplasmosis. It has world-wide epidemiology. Toxoplasmosis infects about 25-30% of the world population.

Did You Know? 

“Protozoa” means “first animals” in Greek. 

Ford and Dutton detected Trypanosoma as the cause of Gambian fever which later turned into African Sleeping sickness in 1992.

The transmigration of Entamoeba histolytica remains for about 30-40 years in human beings. This protozoan parasite can invade the intestinal mucosa and spread to other organs like the liver, etc.