Health > Housing and malaria

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Alcock (1925) wrote thus :
“ There is no general concord of evidence that the insect [A. maculipennis)
prefers the blood of cattle to that of horses or pigs or rabbits or man, though
there would perhaps be more general agreement that it prefers a cattle-shed or
a stable even when empty to a well-constructed house, even when it is habited.”
Wesenberg-Lund (1920-21) assumes that, formerly, in Denmark, A. maculipennis
bit in the open by day. He attributes the disappearance of malaria in Denmark during
the last hundred years to the fact that animals are now housed and man’s working
time in the fields is much lessened by mechanisation ; and A. maculipennis has
followed the animals into their stables. It should, however, equally have followed
man to his house, if that were the complete explanation. There is no mention made
of what, on the evidence given above, is clearly of great importance—’the general
improvement in light and airiness of Northern European habitations during the last
hundred years, a change in which Denmark has certainly participated. It is, perhaps,
not going much too far to suggest that the type of cottage used in these latitudes by
man a hundred years ago was not far different in these respects from the type of
animal house now in use ; and it would seem, then, that the change in anopheline
habitat in Denmark is more reasonably attributable to better housing of man than
the housing at all of animals. That animals are more attractive to A. maculipennis
than is man is, then, a position which was practically receded from by Roubaud
when he insisted that, to be so, they must be stabled in a particular way. The practical
question which results seems to be this : As a malaria preventive, is it not better to
house man well than to house animals badly ?
It must, however, be noted that Missiroli and Hackett (1930) conclude, as
the result of their investigations in Italy, as follows :
“ We believe, therefore, that, in Southern Europe at least, it is not any
combination of attractive physical circumstances, such as darkness, warmth,
dampness and freedom from draughts, which impels maculipennis to enter
dwellings; but, instead, the presence of a certain kind of food-supply to which by
instinct it is drawn.”
9. EFFECT OF CERTAIN PREVENTIVE MEASURES.
It is clear that, if the house is the place where infection is ordinarily obtained
—the place, that is, where man is ordinarily bitten by infected anopheles—then
certain measures which effectively prevent infective anopheles from biting man in
the house will lessen or prevent malarial infection. Conversely, if malaria lessens or
disappears after such measures have been applied, this fact will be good evidence that
the house is a place, or the place, where infection is obtained. The effects of three such
measures will now be considered : {a) effects of detection and destruction of adult
anopheles in houses, (b) effects of screening houses, and (c) effects of house site.