Protozoa

Infectious diseases are caused by prions, viruses, rickettsia, chlamydia, bacteria, pathogenic fungi and protozoa.

Roughly 253 scientists from 21 countries worked for five years to decipher the genetic blueprints of the single-cell parasites that cause sleeping sickness, leishmaniasis and Chagas disease. Experts say the disease-causing protozoa, which affect 500 million people in the tropics and sub-tropics at any one time, look identical under the microscope, but are spread by different flying insects.

The parasite is a one-cell protozoa like ones you might have seen under a classroom microscope, floating around in fluid.

The researcher's team chose to study 10 common species of the ciliated protist – or protozoa microorganisms – because of their ability to reproduce.

Unnamed protozoa has been discovered frozen inside the ice of Antartica.