The History of Malaria in Finland
Hulden, L. and Hulden, L. 2009. The decline of malaria in Finland -- the impact of the vector and social variables. Malaria Journal 8: 10.1186/1475-2875-8-94.
In a test of this hypothesis, Hulden and Hulden (2009) analyzed malaria statistics that were collected in Finland from 1750 to 2008 via correlation analyses between malaria frequency per million people and all variables that have been used in similar studies throughout other parts of Europe," including temperature data, animal husbandry, consolidation of land by redistribution and household size.
Hulden and Hulden report that "malaria was a common endemic disease in Finland in the 18th and 19th centuries and prevalent in the whole country," and they say that "mortality during malaria epidemics usually varied between 0.85 and 3%." Thereafter, however, they found that "malaria declined slowly in Finland without any deliberate counter-measures," such that "the last epidemic in Helsinki occurred in 1902" and "during the 1930s malaria was close to extinction." Over the entire period, in fact, they report that "malaria frequency decreased from about 20,000-50,000 per 1,000,000 people to less than 1 per 1,000,000 people."
When malaria was still common in the country, however, they did find that "high peaks in malaria followed high temperatures in June-July," but they also found that overriding this within-year temperature response over the long term, "both highs and lows in malaria frequency [were] declining independently of temperature trends."
The two Finnish researchers state that "indigenous malaria in Finland faded out evenly in the whole country during 200 years with limited or no counter measures or medication," making that situation "one of the very few opportunities where natural malaria dynamics can be studied in detail." And their study of that unique situation indicated that "malaria in Finland basically was a sociological disease and that malaria trends were strongly linked to changes in the human household size and housing standard," which changes were clearly strong enough to overcome what climate alarmists look upon as a sure enhancer of malaria, i.e., rising temperatures.