Above: Map showing countries (in red) where there is a risk of malaria infection (USCDC, Wikimedia Commons)

Imagine you’re the leader of a country with less financial wealth and a lower life expectancy than Canada. Your government has a limited budget, but you still have a lot to do. For example, you have to build schools and maintain roads. But you also have to manage diseases. How do you decide where to spend the money you have at your disposal?

Managing diseases is more expensive than you might think. Take the example of malaria. In many countries, this deadly infection is a thing of the past. For example, the United States was declared malaria-free in 1949. Dozens of other countries are aiming to eradicate (get rid of) malaria by 2020. Still, as of 2016, over three billion people around the world are still at risk of getting malaria. They mainly live in Africa, Asia and South America.

Communities at risk for diseases like malaria need doctors, nurses, clinics, and medication to help with treatment and prevention. These are examples of direct costs associated with a disease. According to the US Centers for Disease Control and Prevention, the world spends up to 12 billion US dollars on malaria every year.

But did you know that diseases also have less obvious, indirect costs? Here are two examples of the silent costs of malaria.

Did you know? Malaria means “bad air” in medieval Italian.

Malaria can make you more vulnerable to Salmonella

Scientists think that malaria parasites interfere with the human immune system. That’s why people with malaria are more susceptible to infections.

For example, if you have malaria, you’re more likely to get infected by bacteria called Salmonella. These bacteria could enter your body if you accidentally ate food contaminated with animal feces. People infected with Salmonella can experience vomiting, stomach cramps and fever. In the most severe cases, Salmonella can kill.

Malaria parasites spread through the human body through blood vessels. As they spread, they burst open red blood cells, searching for more blood cells to infect. When malaria parasites burst open a red blood cell, the cell releases chemicals. In turn, these chemicals make the body release immune cells called neutrophils.

Neutrophils target and destroy bacterial invaders. But sometimes, burst red blood cells release neutrophils before they are ready for action. These premature neutrophils cannot kill Salmonella effectively. This is how malaria weakens your immune system, making it harder for your body to fight off a Salmonella infection.

Did you know? Typical malaria symptoms are similar to flu symptoms: fever and chills.

Malaria can make you a bad student

Here’s another silent cost: children infected with malaria have trouble in school. Not only that, but malaria-infected kids show symptoms of attention deficit hyperactivity disorder (ADHD). These behaviours can make it harder for children to learn in the first place.

About one percent of all malaria cases end up infecting the patient’s brain. This condition is called cerebral malaria. Its consequences can last a long time. Studies have found that patients still have trouble with speaking, hearing, behaviour and other cognitive (thinking) functions even after they have been cured of their malaria infection.

Did you know? Malaria is caused by several different species of parasites in the genus Plasmodium. These parasites are carried and spread by mosquitoes.

Why does malaria affect how kids perform at school? Scientists think there are many reasons. Some of them are pretty obvious. For example, if you were up all night with a fever, would you be able to concentrate the next day? How about if you had a condition that made you tired all the time? Well, that’s what happens when you have anemia, another malaria symptom. For millions of school kids infected with malaria, simply getting up and going to school—let alone acing exams—is a huge challenge!

Some young people infected with malaria don’t show any symptoms of malaria. However, researchers have found that these students still have the same problems in school. This is a big challenge for scientists who study malaria’s impacts on education!

Did you know? Treatments that prevent a disease or infection are called prophylaxis.

Dealing with the silent costs of malaria

There are ways to minimize these silent costs. For example, when doctors treat malaria in a high-risk area, they can also prescribe drugs that target Salmonella. Also, the results of clinical trials suggest that some drugs may help prevent malaria in school children. So rather than deal with the effects of malaria, it may be possible to prevent children from being infected in the first place.

Controlling diseases is important work. But for leaders of countries with limited resources, disease control is difficult because it takes money and resources away from other important things. But think of the silent costs of malaria, like the increased risk of other infections and poorer student performance. Can you see how a malaria-free world would be great for the health of both people and economies around the world?

Learn More!

About malaria in general:

Impact of malaria (2016)
US Centers for Disease Control and Prevention

Cerebral malaria: Mechanisms of brain injury and strategies for improved Neurocognitive outcome (2010)
R. Idro, K. Marsh, C.C. John and C.R.J. Newton, Pediatric Research 68(4)

About malaria and other infections:

Malaria impairs resistance to Salmonella through heme—and heme oxygenase—dependent dysfunctional granulocyte mobilization (2011)
A.J. Cunnington, J.B. de Souza, M. Walther and E.M. Riley, Nature Medicine 18
Link to abstract. Free registration required to view the full article

WHO guidelines for antimicrobial treatment in children admitted to hospital in an area of intense plasmodium falciparum transmission: Prospective study (2010)
B. Nadjm et al., British Medical Journal 340

Tsukushi Kamiya

I’m originally from Tokyo, but science has allowed be to become a citizen of the world. I did an undergraduate degree in ecology at the University of Otago, New Zealand. A project on parasitic flatworms kindled my enthusiasm for science, especially ecology and the evolution of parasitic organisms. Craving new experiences, I moved to Europe where I completed an international master’s programme in evolutionary biology. I took courses and conducted research projects at three different universities in Sweden (Uppsala), France (Montpellier) and the Netherlands (Groningen). Now I’m a PhD student at University of Toronto. Using computer simulations, my project explores how infectious diseases spread and evolve in the face of public health interventions. I love dogs! I also like playing and watching football (or soccer, as they call it in Canada).







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