Independently of Demarquay (No. 5344.3) and Wucherer (No. 5344.6), Lewis found microfilariae in the urine and blood in chyluria. He was first to use the term Filaria sanguinis hominis for the parasite.

 The first quantitative study of leprosy in India. Leprosy first appeared in India at least 2,000 years ago and continued to exist throughout the subcontinent over the succeeding centuries. Upon the establishment of the Indian Raj in 1858, the colonial authorities began to assume a more professional and scientific attitude towards public health. The severity and geographic distribution of leprosy in India was unknown until it was surveyed in the British Indian Census of 1872, the statistics of which prominently feature in this report. Includes two chromolithographed disease maps. Digital facsimile from the Internet Archive at this link.

Lewis made the critical connection/association of the worm, Filaria sanguinis,(Wuchereria bancrofti ) to Elephantiasis. This brief account appears to be a third person account summarizing Lewis's work written by an editor of the Indian Medical Gazette. Digital facsimile from PubMedCentral at this link.

Lewis published a formal paper in Lancet: "Filaria sanguinis hominis (mature form), found in a blood clot in Naevoid Elephantiasis of the scrotum," Lancet, II (1877) 453-455.

(Thanks for Juan Weiss for these references.)

First description of a trypanosome (T. lewisi) in a mammal. Seoarate edition in book form with the same title: Calcutta: Office of the Superintendent of Government Printing, 1879.