This is an excerpt from a letter to Nature published in 1870, written by E. L. Layard, an English naturalist living in South Africa.
Permit me to add my mite to Mr. Horace Waller’s theory respecting the utility of mosquito curtains in warding off fever, generated by the miasma of decaying vegetation.
When the body is relaxed in sleep and the pores of the skin act freely, then is the time that the deadly miasma, cold and damp, even in the tropics, seizes on its victim. What jungle traveller does not know the feeling of the air an hour and a half or two hours before daylight? But the warmth from the body and breath within a well-secured mosquito net, I think effectually protects the sleeper.
Layard was right about mosquito nets providing protection from malaria, but wrong about the reason. He thought – along with many others – that diseases were caused by miasma, a type of foul air. The word “malaria” itself reflects this misconception: mal (bad) + aria (air). The real reason why mosquito nets are effective is, of course, because they keep out mosquitos, which spread the parasites that cause malaria.
I mention this because researchers are apparently on the brink of developing a malaria vaccine, having seen extremely promising results from early trials. This could be huge – malaria causes around a million deaths a year, and many times this number of people fall sick.
It also highlights how science, perhaps more so than any other human endeavour, is truly progressive. In less than 150 years we have gone from believing malaria was caused by noxious air to discovering its real cause (infection by Plasmodium, a protist parasite); elucidating the fascinating co-evolutionary history of humans and malarial parasites; and now, apparently, developing a promising vaccine. Perhaps one day we’ll add malaria to smallpox, polio, measles and rubella in the graveyard of eradicated (or nearly eradicated) diseases.
Scientists: what other group does so much for human welfare, and receives so little thanks?