The most vulnerable are persons with no or little immunity against the disease. In areas with high transmission (such as Africa south of the Sahara), the most vulnerable groups are:
- Young children, who have not yet developed partial immunity to malaria
- Pregnant women, whose immunity is decreased by pregnancy, especially during the first and second pregnancies
- Travelers or migrants coming from areas with little or no malaria transmission, who lack immunity.
In areas with lower transmission (such as Latin America and Asia), residents are less frequently infected. Many persons may reach adult age without having built protective immunity and are thus susceptible to the disease, including severe and fatal illness.
Social and Economic Toll
Malaria imposes substantial costs to both individuals and governments.
Costs to individuals and their families include purchase of drugs for treating malaria at home; expenses for travel to, and treatment at, dispensaries and clinics; lost days of work; absence from school; expenses for preventive measures; expenses for burial in case of deaths.
Costs to governments include maintenance, supply and staffing of health facilities; purchase of drugs and supplies; public health interventions against malaria, such as insecticide spraying or distribution of insecticide-treated bed nets; lost days of work with resulting loss of income; and lost opportunities for joint economic ventures and tourism.
Direct costs (for example, illness, treatment, premature death) have been estimated to be at least US$ 12 billion per year. The cost in lost economic growth is many times more than that.