Malaria as a Numbers Game

I just returned from my first trip to India and all of my friends wanted to know if I experienced any culture shock.  Since I’ve traveled a fair amount in developing countries, I tend to feel that life is life is life.  Overall, it’s food, it’s shelter, and it’s taking care of one’s family, the same here as the Sahara and the Andes and the streets of Delhi, it’s just different in the details.  So, not much really shocks me, and to their question, I’d say, “No, India wasn’t so shocking…  But…”

But there was one palpable difference in my experience in India than any other country I’ve visited—THERE ARE SO MANY PEOPLE.  Sure, I’ve read about the population growth of India and China and we talk about the how the epidemiological transition is going to hit there big time, but to visualize what was previously abstract provided a whole new perspective on ‘crowded’.

This brings me to my topic:  if you underestimate a burden of disease in India, you underestimate the burden globally, in a significant manner.   And that is what has been happening with malaria.  Because WHO statistics outside of Africa largely rely on data from health facility reporting, deaths and morbidity experienced outside of clinical settings go unrecorded. Dhingra et al conducted verbal autopsies for febrile deaths and physicians coded the results as malaria or not.  The authors found that only 13% of malaria deaths in India were recorded by WHO reporting systems.  Therefore, in contrast to the 15,000 deaths from malaria in India for 2006 estimated by the WHO, this study estimated that 205,000 deaths were directly due to malaria, with a range from 125,000-277,000.

Malaria Mortality, New Estimate vs WHO Estimate. From Dhingra et al, The Lancet. 20 November 2010.

This is a major deal, considering the estimated GLOBAL total of deaths for that year was 863,000.  Factoring in India’s new estimate puts global deaths over 1 million, with India alone accounting for 19% of all malaria deaths that year, surpassed only by the number of malaria deaths in Nigeria.

Now, I’m not saying that we should stop focusing on Africa and switch to Asia—an either/or approach will never work towards the goal of elimination, but what we should focus on is this:

  1. Numbers are not always accurate, especially coming from countries without strong health systems, and should always be taken with a grain of salt.
  2. Together China and India account for 40% of the world’s population, each country individually having more people than the entire continent of Africa.   Therefore, the sheer populations of countries such as India and China, mean that even if these countries have a lower prevalence of disease, they necessarily have a large, absolute burden of disease. For an example, check out these malaria maps compiled from Tatem et al in a recent Lancet article:
  3. Malaria maps showing absolute numbers of those at risk for malaria versus proportion of population.

    Comparison of numbers of people at risk for malaria versus proportion of population

The take home message is that malaria is much more widespread than we believe it is, and though we are making some great strides towards reducing global malaria incidence, we have a long way to go.

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