Importancia de la viruela, gastroenteritis aguda y paludismo ... - Oulu

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6.4 Malaria
− Malaria was endemic in Finland during the period under study, mainly in the coastal
areas. There were also some cases inland, but they were rarer. The clearly endemic
zones were located in the southwest of the country, especially the Åland Islands, but
also the regions of Uusimaa, Itä-Uusimaa and Varsinais-Suomi.
− Malaria was an important modulating factor of the health state of the population, as it
could act weakening and predisposing people to suffer from other diseases. It caused
less than one per cent of all deaths during the period under study, but considering the
low case-fatality rate of Plasmodium vivax, the prevalent parasite in Finland, the
actual proportion of sick people must have been quite large.
− The importance of malaria varied from year to year, not following a pre-determined
trend or external perturbations of the population such as wars or famines. Those
periods of higher malaria incidence were probably a reaction to environmental
changes in terms of temperature or humidity. Temperature was probably an important
limiting factor: low temperatures implied low incidence of malaria but not necessarily
the other way round.
− The most affected age groups were children 1 to 4 years old and old people, which
reinforces the idea of endemic malaria in the country.
− Most of the malaria deaths took place in spring, which is common in areas infected
with the hibernans strain of Plasmodium vivax. In the coastal areas a slightly different
seasonality can be observed, with a minor sub-peak in autumn. This autumnal portion
of malaria mortality could be the consequence of infections with P. malariae but it is
more plausibly related to more subtropical strains of P. vivax.
− During the period under study it can be observed a gradual process of stabilization of
malaria in specific areas: during the last half of the 18th century there were peaks of
the disease in a larger number of areas than during the first half of the 19th century.
There is also a gradual reduction of the mean age of malaria deaths, even if the general
average age at death tends to increase gradually.