Geoscience Reference
In-Depth Information
risks here, too: for example, long-term pesticide use encourages the breeding of resistant
strains, while killing many natural predators of pests.
The most important vector-borne disease is malaria, with currently 500 million infected
people worldwide.
Plasmodium vivax
, which is carried by the
Anopheles
mosquito, is the
organism that causes malaria. The main climate factors that have a bearing on the malarial
transmission potential of the mosquito population are temperature and precipitation.
Assessments of the potential impact of global climate change on the incidence of malaria
suggest a widespread increase of risk because of the expansion of the areas suitable for
malaria transmission. Mathematical models mapping out the suitable temperature zones
for mosquitoes suggest that by the 2080s the potential exposure of people could increase
by 2-4 per cent (260-320 million people). The predicted increase is most pronounced at
the borders of endemic malarial areas and at higher altitudes within malarial areas. The
changes in malaria risk must be interpreted on the basis of local environmental conditions,
the effects of socioeconomic development, and malaria control programmes or capabilit-
ies. The incidence of infection is most sensitive to climate changes in areas of South-East
Asia, South America, and parts of Africa. Climate change will also provide excellent con-
ditions for
Anopheles
mosquitoes to breed in southern England, continental Europe, and
the northern USA.
It should, however, be noted that the occurrence of most tropical diseases is related to de-
velopment. As recently as the 1940s, malaria was endemic in Finland, Poland, Russia, and
36 states in the USA including Washington, Oregon, Idaho, Montana, North Dakota, New
York, Pennsylvania, and New Jersey. So although global warming has the potential to in-
crease the range of many of these tropical diseases, the experience of Europe and the USA
suggests that combating malaria is strongly linked to development and resources: develop-
ment to ensure efficient monitoring of the disease and resources to secure a strong effort
to eradicate the mosquitoes and their breeding grounds.
