SCIENCE LITERACY WORKING WITH DATA

Accurate estimates of deaths due to malaria are important for many reasons, including decisions regarding vector control and health interventions, and also to direct charitable donations effectively. A recent analysis estimated much higher annual death rates from malaria than did previous studies, with the majority of the increase coming from victims over age 5. The table below shows the annual number of deaths from malaria in different world regions, estimated by the Institute for Health Metrics and Evaluation (IHME) and the World Health Organization (WHO).

Comparison of IHME and WHO Estimates of Malaria Deaths by WHO Region

Interpretation

Question 5.15

Describe in one sentence what the table shows about the total number of deaths due to malaria.

IHME estimates 1.2 million deaths, almost double the WHO estimate of 655,000 deaths.

Question 5.16

What region of the world has the highest mortality due to malaria? What proportion of the world total comes from this region?

Most malaria deaths are from Africa, and they account for 88.8% (IHME) or 91% (WHO) of total deaths due to malaria in the world.

Question 5.17

What percentage and what number of malaria deaths do IHME and WHO estimate are of children under age 5?

IHME estimates 58% or 717,736 children under the age of 5; WHO estimates 86% or 563,300.

Advance Your Thinking

Question 5.18

In which region are the new mortality estimates most enlarged? Why do you think this might be the case?

The new estimates for both Southeast Asia and Africa are double previous estimates, although actual numbers are much higher in Africa. Probably those regions have poor reporting of cause of death compared to the other regions.

Question 5.19

It is often extremely difficult to estimate the cause of death in a developing country; health workers rely on a “verbal autopsy,” in which they ask surviving family members a series of questions about the deceased’s symptoms. If it were possible to confirm that a person who died was or was not infected by malaria, rather than relying on verbal autopsies, would you predict that the estimates of mortality from malaria would increase or decrease? Explain your reasoning.

Possible answer: Lower, because people could be infected with malaria but die of other causes. Furthermore malaria could make them more vulnerable to other diseases or conditions and so make them more likely to die (but not be the true cause of death). Alternatively, mortality estimates could be higher, because older people might have been assumed to die of old age but because they have weaker immune systems they might have died of a malaria infection.