The SARS - CoV - 2 pandemic of 2019 first started in Wuhan China and spread across the world. Had an unexpected worldwide impact in 2020. However in 1681, Antonie Van Leeuwenhoek of Holland was observed Giardia in his stool. In 1870, Louis Pasteur a studied silkworm disease was firstly published a research - based study on protozoa diseases to its primary control and prevention in South Africa. In 1878, Patrick Manson has discovered the role of mosquitoes in filariasis. This was the first confirmation of vector transmission. In 1880, Laveran a French physician who discovered malarial parasites.