Louis Westenra Sambon (original first name Luigi, 7 November 1867 – 30 August 1931[1]) was an Italian-English physician who played important roles in understanding the causes (etiology) of diseases.

He described many pathogenic protozoans, insects, and helminths including the name Schistosoma mansoni for a blood fluke.

[2] He was an authority on the classification of parasitic tongue worms called Pentastomida (Linguatulida),[3] and one of the genus Sambonia is named after him.

[1] His father was an Italian soldier Commendatore (Commander) Jules Sambon,[4] and her mother, Laura Elizabeth Day, was a distant relative of Charles Dickens.

He attended Hoddesdon (Hertfordshire) Grammar School, studied at the College Gaillard in Lausanne, and the Liceo Umberto in Naples.

[9] Sambon's theory was proved right in the 1890s when it was confirmed that yellow fever was caused by a virus and transmitted by mosquito.

[10] One of the co-discoverers and who helped eradicate yellow fever in Havana, William Gorgas told Sambon, saying, "My colleagues and I are pleased to have been able to prove that you were right.

Castellani discovered that patients with sleeping sickness had a protozoan parasite (Trypanosoma) in their cerebro-spinal fluid, and sometimes together with bacterial (Streptococcus) infection.

[14] Sambon introduced the parasitic theory at the meeting of the British Medical Association in 1905, in which he stated that pellagra was an infectious disease something like kala-azar (caused by a protozoan Leishmania) in India.

His theory was supported by the discovery of a cancer-causing roundworm (Gongylonema neoplasticum) by a Danish physician Johannes Fibiger in 1907.