When Is Mosquito Day?
For those who don't know, August 20th was named Mosquito Day by Ronald Ross.
On this day in 1897, in Secunderabad, India, Ross dissected anopheline mosquitoes which had fed on a malarious patient called Husein Khan on August 16th: From August 17th-21st, Ross dissected the mosquitoes, and on Aug 19th identified some 'peculiar vacuolated cells' on the stomach of the mosquito. The next day (20th) he dissected another mosquito, and found many of these cells on the stomach wall of the mosquito. He concluded that these were the malaria parasite stages in the mosquito (we now know them as oocysts).
The significance of this is that until then, no-one had any idea of how parasites in the blood of malarious patients was transmitted via mosquitoes. There were many theories - for example that infected water carried the parasite from drowned mosquitoes into people when they drank it. Further experiments by Ross showed that the oocysts contained sporozoites, which later on appeared in the salivary glands, and that these salivary gland parasites were able to produce malaria infection (in this case, of birds). It is for this work that Ross was awarded the Nobel Prize for Medicine in 1902. There is a plaque commemorating the discovery in Secunderabad.
You can find out more about Ronald Ross in the biography written by Ted Nye and Mary Gibson: Ronald Ross: Malariologist and Polymath, pubd. 1997 (Macmillan Press, UK).
Lisa Ranford-Cartwright, Ph.D.
University of Edinburgh
Institute of Cell, Animal and Population Biology,
West Mains Road,
Edinburgh, EH9 3JT, Scotland,
UK Tel: (UK)131-650-8662 Fax: (UK)131-668-3861