Climate change futures: health, ecological and economic dimensions

Figure 2.4 Malaria and Floods in Mozambique
Malaria Cases
1000
900
800
700
600
500
400
300
200
100
0
1 13 25 37 49 61 73 85 97 109 121 133 145
Weeks weeks (Jan99-Dec01)
3.5
3
2.5
2
1.5
1
0.5
0
malaria cases
Maputo maputo precip
Malaria surged following six weeks of flooding
in southern Mozambique.
Source: Avaleigh Milne
36 | INFECTIOUS AND RESPIRATORY DISEASES
CASE STUDIES
FLOODING IN MOZAMBIQUE
In February and March of 2000, Mozambique experienced
a devastating series of three tropical cyclones
and heavy rains over a six-week period. Hundreds of
people were killed directly from drowning and hundreds
of thousands were displaced by the area’s worst
flooding on record. The post-flood propagation of mosquitoes,
coupled with increased risk factors among the
population (including malnutrition and destroyed houses
and infrastructure) led to a malaria epidemic.
Washed-out roads and bridges impeded emergency
relief and access to care.
In southern Mozambique, the area hit hardest by the
floods of 2000, records from regional health posts
and district hospitals before and during the flooding
demonstrated the impacts. Daily precipitation and
maximum temperatures from two regional observation
stations — Maputo (the capital) and Xai-Xai —
showed a four-to-five fold spike in malaria cases following
the flooding, compared with otherwise relatively
stable levels over three years (see figure 2.4).
DROUGHT IN BRAZIL
Three centuries of sugar plantations in northeast Brazil
drained water from the region’s aquifers to send as
rum across the Atlantic to fuel the “triangular trade.”
The altered microclimate and recurrent drought has left
the region impoverished. Recurrent crop failures and
hunger has driven job-seeking migration from rural to
urban areas, bringing with it a cohort of humans carrying
malaria (Confalonieri 2003). Sometimes uninfected
migrants move into heavily infected areas in the
Amazon and return to their home regions with heavy
burdens of disease.
During the El Niño-related intensified droughts of the
1980s and 1990s, many inhabitants of the state of
Maranhão migrated to the neighboring Amazon
region, which has a high rate of malaria. As the
drought abated, migrants returned to their homelands,
causing a sharp rise in imported malaria.
PROJECTIONS FOR ZIMBABWE
Roughly 45% of the population of Zimbabwe is currently
at risk for malaria (Freeman 1995). A variety of
model projections of the impacts of climate change on
the range and intensity of malaria transmission have
shown that changes in temperature and precipitation
could alter the transmission of malaria, with previously
unsuitable areas of dense human population becoming
suitable for transmission (Lindsay and Martens 1998;
Martens et al. 1999; Rogers and Randolph 2000).
Despite using different methods and reporting different
results, the various models reach similar conclusions:
The future spread of malaria is likely to occur at the
edges of its geographical distribution where current climate
limits transmission.
Notably all these analyses are based upon projected
changes in average temperatures, rather than the more
rapid increase in minimum temperatures being
observed; and thus may underestimate the actual biological
responses.
ECONOMIC DIMENSIONS
Good population health is critical to poverty reduction
and long-term economic development. Malaria
reduces the lifetime incomes of individuals, national
incomes and prospects for economic growth. With