In many parts of the world, a mosquito bite is just an annoying itch. But in tropical areas, it can lead to something much more serious: malaria. Malaria is a deadly disease that affects about half of the world’s population. It’s not the mosquito itself that causes malaria; instead, mosquitoes act as carriers, or vectors, for a tiny organism called Plasmodium. This parasite lives in the mosquito’s saliva and can cause symptoms like weakness, aches, high fever, and even death if not treated.
There are five types of Plasmodium that can infect humans, but the most dangerous one is Plasmodium falciparum, responsible for 90% of malaria deaths. The process begins when a mosquito bites someone who already has the parasite in their blood. Later, the mosquito bites another person, passing the parasite through its saliva. Once inside the human body, the parasite invades red blood cells, causing them to burst.
Not all mosquitoes can carry malaria. Only mosquitoes from the Anopheles genus can transmit the disease, and even then, only the females feed on human blood. These mosquitoes are found worldwide, except in Antarctica. However, malaria isn’t present everywhere because Plasmodium parasites can’t survive in cold temperatures. They thrive in warm climates, especially around 27 degrees Celsius.
Malaria is more common in areas with warm, humid climates. Mosquitoes lay their eggs in stagnant water, so they need moisture to breed. This is why malaria is prevalent in about 90 countries near the equator, where conditions are perfect for both mosquitoes and Plasmodium to thrive.
As the world gets warmer, the areas where mosquitoes can live and breed might expand. This means malaria could spread to new regions. In developed countries, people have found ways to control malaria, like avoiding swampy areas and using mosquito control methods.
Human activities can either help control or spread malaria. For example, clearing wetlands and improving sanitation can reduce mosquito breeding. However, activities like mining, poor waste management, and rapid urbanization can create ideal conditions for mosquitoes. When people move into new areas, they might bring the parasite with them, increasing the risk of malaria.
Controlling malaria requires cooperation between governments, organizations, and communities. Better sanitation, waste disposal, and land management can help reduce mosquito populations. Wealthier countries can afford treatments to eliminate the disease, but poorer nations often struggle with limited resources.
To effectively combat malaria, a global effort is needed. Partnerships between countries and organizations are crucial to reducing malaria in the most affected areas. By working together, we can make progress in controlling and eventually eradicating this deadly disease.
Using craft materials, create a model of the mosquito lifecycle. Include stages such as egg, larva, pupa, and adult. This will help you understand how mosquitoes develop and why stagnant water is crucial for their breeding. Present your model to the class and explain each stage.
Participate in a role-playing game where you act as either a mosquito, a human, or the Plasmodium parasite. Through this game, you’ll simulate how malaria is transmitted and discuss strategies to prevent its spread. Reflect on what you learned about the roles each plays in malaria transmission.
Research how climate change might affect the spread of malaria. Create a presentation to share your findings with the class, focusing on how warmer temperatures could expand mosquito habitats and increase malaria risk in new regions.
Work in groups to design a campaign aimed at preventing malaria in a specific region. Consider factors like local climate, mosquito control methods, and community education. Present your campaign to the class, highlighting key strategies for reducing malaria risk.
Create an interactive map showing regions where malaria is prevalent. Use data to highlight environmental factors that contribute to malaria spread, such as temperature and humidity. Share your map with the class and discuss how these factors influence malaria distribution.
**Sanitized Transcript:**
[Music] Across the developed world today, the bite of a mosquito might at worst mean an irritating interruption to a warm summer’s evening on the porch. However, if you happen to live in a more tropical climate, that itch could be the start of something far worse. In fact, as much as half of the world’s population is at risk of a deadly infection called malaria due to the bite of this blood-sucking insect. The disease isn’t actually caused by the mosquitoes; they are what we call a vector. These buzzing little insects are the vehicles for the actual killer lurking inside their saliva glands: a microscopic single-celled organism called Plasmodium, which is responsible for symptoms like weakness, aches, intense fever, and, for an unlucky percentage who don’t receive treatment, even death.
There are five species of Plasmodium that infect humans, but the most dangerous is called Plasmodium falciparum, which causes 90% of all malaria deaths. All these parasite species spread the same way: mosquitoes pick up Plasmodium by biting a previously infected person who has the parasite in their blood. Later, the same mosquito delivers the parasite to another host through its saliva. The dangerous microbes quickly find their way inside red blood cells, where they breed in such numbers that the cells swell up and eventually explode.
Fortunately, not all mosquitoes are suitable carriers; in fact, just one genus will do for this picky parasite: a type of mosquito called Anopheles. Even then, it’s only the female mosquito that feeds on human blood to nourish her young; males prefer to dine on nectar. There are more than 40 species of this particular mosquito across the world, found on every continent except Antarctica. They are all capable of carrying malarial parasites, yet not all countries have cases of malaria. Why not? Plasmodium microbes have no tolerance for the cold. The deadliest species, for example, can’t reproduce if the temperature falls too far below 20 degrees Celsius. On the other hand, at 27 degrees, the microorganisms thrive and multiply with staggering speed.
Colin Sutherland, a professor of parasitology at the London School of Hygiene and Tropical Medicine, explains that this speed makes a tremendous difference. After a mosquito picks up the parasite by feeding on the blood of an infected person, it needs 15 to 20 days for the parasite to fully mature inside and expand within the mosquito. If you think about the lifespan of the average mosquito, 20 days is pushing it. The mosquito has to survive that period of time, and in colder regions, the parasite develops slower. So it’s a race between the parasite getting ready to go to another person and the mosquito dying in colder places.
We used to have some malaria in southern England, but it’s much easier to control because it’s right on the edge of the temperature required. Mosquitoes also need moisture, and a lot of it. These insects lay their eggs in pools of stagnant or slow-moving water, where they hatch into larvae. The adults’ delicate bodies are also susceptible to drying out, meaning they prefer humid atmospheres. These conditions tend to rule out dry countries, but for about 90 countries spread around the equator, both Anopheles and Plasmodium have the perfect conditions to thrive: warm enough for the parasite to grow quickly and wet enough for the mosquito to spread it.
You might not want to get too comfortable, though, as the world continues to warm and climates change. This tropical humid zone could expand, opening the way for Anopheles mosquitoes to breed in more environments, and perhaps malaria will move with it. If you’re lucky enough to live in a more developed part of the world, there are already ways to keep malaria at bay. We’ve known about some of them for centuries. Ancient texts on urban planning describe the importance of avoiding noxious wetland areas such as swamps and marshes. The word malaria itself comes from the old Italian words meaning “bad air.”
Before people knew much about the transmission of parasites, foul air near stagnant pools was considered responsible for causing illness. While the smell might be relatively harmless, stagnating warm water makes for the perfect mosquito breeding ground. In many parts of the world, humans have done a good job of eradicating mosquitoes by fumigating, clearing away rubbish, and draining wetlands. However, in other areas, human activities encourage mosquitoes to breed, from digging up the earth for mines to leaving buildings to crumble, abandoning tires and other rubbish, and having inadequate drainage where predator-free puddles form, allowing mosquito eggs to hatch in peace.
Moving populations can also create the right conditions for malaria to spread, not just by carrying the parasite with them but by changing the landscape to suit breeding mosquitoes. Caroline Maxwell works with a charity group, Malaria No More. According to her, as people are forced to move into unplanned settlements, the environment can change with them. One of the biggest challenges around malaria control is urbanization or people moving into spontaneous settlements such as shantytowns. When this is done rapidly and without control, it can lead to poor drainage systems and stagnant water, which can increase mosquito breeding.
It’s crucial for governments and town planners to work together to ensure that drainage and other projects are done in a systematic way to reduce exposure to mosquitoes that carry malaria. Destroying natural environments is also increasing the risk of bringing more people into contact with this deadly disease. Dr. Sutherland describes another example where humans moving into new areas can increase the risk of disease. There’s a kind of malaria that is at home in the monkeys of Southeast Asia, who mainly live in the forests and rarely interact with humans. However, as the environment is being changed and forests are cleared for plantations and human habitation, the monkeys are forced to live closer to humans. Now, the mosquitoes that bite those monkeys are also biting humans, leading to an increase in this type of malaria.
With enough funding, countries might be able to afford better sanitation and efficient waste disposal programs to keep their environment free of standing water, wiping out mosquitoes before they can breed. Governments can designate land as national reserves, preventing it from being cleared. Wealthier nations can also afford treatments to eliminate the illness from human populations, driving Plasmodium to extinction with preventative medications. Unfortunately, not all nations have such resources. In less economically developed countries, individuals’ poverty may mean they can’t afford these treatments or don’t complete their prescriptions, which increases the parasites’ resistance to medication.
If we are to ever have hope of controlling and wiping out malaria, we need to consider how to work together in this fight. There’s an acceptance that it takes a global level of effort from partnerships between many countries and organizations to make a difference. It has taken that level of effort to push back this disease, locality by locality, step by step, reducing malaria in the most vulnerable places first and then moving on. [Music]
Malaria – A disease caused by a parasite transmitted to humans through the bites of infected mosquitoes. – Malaria is a serious health issue in tropical regions where mosquitoes are prevalent.
Mosquito – A small flying insect that feeds on the blood of animals and humans, often spreading diseases. – Mosquitoes are known to transmit diseases like malaria and dengue fever.
Plasmodium – A genus of parasites that cause malaria in humans and other animals. – The Plasmodium parasite undergoes part of its life cycle in the mosquito before infecting humans.
Anopheles – A genus of mosquitoes that are known to transmit malaria. – The Anopheles mosquito is the primary vector responsible for spreading malaria in many parts of the world.
Climate – The long-term pattern of weather conditions in a particular area. – Changes in climate can affect the distribution of species, including mosquitoes that carry diseases.
Environment – The surrounding conditions in which an organism lives, including air, water, and land. – Protecting the environment is crucial for maintaining biodiversity and human health.
Breeding – The process by which animals produce offspring, often influenced by environmental conditions. – Stagnant water provides ideal breeding grounds for mosquitoes.
Sanitation – The practice of maintaining cleanliness to prevent disease and promote health. – Improving sanitation can help reduce the spread of diseases like malaria.
Humidity – The amount of moisture in the air, which can affect living organisms and their habitats. – High humidity levels can increase the survival rate of mosquitoes, leading to more cases of malaria.
Control – The management or regulation of a process or activity, often to prevent harm. – Effective mosquito control measures are essential to reduce the incidence of malaria.
