A parasite pioneer

The concept that infectious biological agents were responsible for many diseases was controversial in the midnineteenth century. But key experiments by famed scientists such as Louis Pasteur and Robert Koch eventually won over sceptics. However, some other researchers, equally convinced by this notion, and who also carried our convincing experiments in its support at the same time, have failed to win the recognition they deserve. One such scientist is Griffith Evans. Born in west Wales in 1835, he trained at the Royal Veterinary College in London after which he obtained a post as a veterinary officer in the British Army. He went first to Canada and was stationed in Montreal in 1861. He registered with the medical faculty at McGill University and graduated as an MD there in 1864. In his graduation thesis on tuberculosis he expressed his views that it was an infection. Although he received challenges to this notion he was not deflected from his belief. “Microscopy was my hobby since my earliest student days. I had kept myself informed of Pasteur’s investigations and discoveries of pathogenetic bacteria, and was deeply impressed with the conviction that a new door was opened for great developments in medical science,” he revealed. Griffith Evans was eventually despatched by the army to India to investigate the cause of a serious epidemic among horses at Sialkot, about 50 miles north of Lahore. He made two important observations. He noted the leucocytosis and the appearance of the large granular white cells. He also identified Bacillus anthracis as the cause of the disease. This was its first observation in India and went against a strong body of opinion that it was not pathogenic. In August 1880 he went to Dera Ismael Khan on the North West Frontier to investigate the disease of horses known as ‘surra’. He was convinced the disease resulted from an infectious agent and demanded several conditions before tackling the problem. I “stated that I could not undertake to investigate the disease unless I was fully authorised to kill as many patients as I wished in any stage of the disease for examination post-mortem; and to make any experiment I might wish to transfer the disease to any healthy animal I would select for the purpose, so that I might know that it is transferrable, and, if so, that I might be able with certainty to study it from its earliest stage onward.” Strong objections were made to giving the authorisation requested but the issue was eventually referred to the Lieutenant Governor of the Punjab personally, who decided entirely in Evans’ favour. Surra is a disease characterised in the horse by an insidious onset and in the late stages by the marked wasting accompanied by a hearty appetite. Griffith Evans wrote in his report: “Some cases at last drop down, and die suddenly, perhaps when they are eating and enjoying food; others become delirious and struggle on the ground as if in pain; while other cases linger for days after they are down, too weak to rise or stand, after they are helped up, Feature