Small Bite, Huge Risk. What Do You Need To Know About Malaria? | Respiratory tract disorders and diseases articles | Body & Health Conditions center

We've all heard of malaria — but how many of us really know much about this mosquito-borne infection that kills hundreds of thousands of people a year?

It's World Malaria Day. The theme, "zero malaria starts with me", first requires you to have all the right info. That's what we're equipping you with today.

Malaria is a parasitic disease caused by one of four microorganisms belonging to the Plasmodium group. It is most commonly spread via the bite of an infected female mosquito from the Anopheles genus. Because the parasites invade red blood cells, malaria can also be transmitted through blood transfusions (if the blood happens to contain the parasites), organ transplant, and from mother to child prior to or during birth, although these routes of transmission are relatively rare.

A (not so) brief history of malaria

Humanity has been struggling with this disease since ancient times, with the first descriptions documented in 2700 BC China, while the first recorded symptoms date back to ancient Greece, mainly thanks to Hippocrates. It has even been widely debated that malaria was possibly one of the more important reasons for the fall of ancient Roman and Greek civilizations.

The name comes from the medieval Italian mal aria, which translates as “bad air”. Before discovering the true nature of malaria, people used to think that this disease was caused by “bad fumes in the swamps”.

Things drastically changed near the end of 19^th century, when parasitic microorganisms in red blood cells were first seen under the microscope. This made the subsequent discovery that malaria was transmitted by mosquito bites possible, paving the way for new methods of fighting the disease.

Throughout history, malaria has found its way from tropical zones to almost every corner of the world, usually with the help of soldiers, merchants and colonists, who even introduced malaria to the New World by unknowingly carrying microorganisms along on their journeys. Malaria has since reigned all the way up to the middle of the 20^th century, when new developments in treatment (the discovery of chloroquine) and prevention (mass insecticide use against mosquitoes) helped eradicate the disease in most of the developed world, where only imported cases are diagnosed.

Today, malaria presents an important public health concern in the poorest regions of sub-Saharan Africa, southeast Asia, and South America. Overall, about 40 percent of the world’s population still live in territories where malaria is transmitted, counting more than 200 million new cases, as well as almost half of million deaths each year — most of them children. That’s almost as many casualties as AIDS.

What causes malaria?

Four Plasmodium species are known to cause malaria in humans: P. falciparum, being the most serious, and P. vivax, P. ovale and P. malariae, which cause a milder form of the disease.

The source of infection is the infected human itself, but the mosquito as a vector is necessary for the parasite to complete its complex reproduction cycle. Because of that, malaria can’t be contracted via direct human-to-human transmission.

The first part of the Plasmodium life cycle takes part in the human body, after a host was bitten by a mosquito carrying the parasite (sporozoite) in its saliva.
When the parasites get into the blood stream, they enter the liver cells where they multiply, producing merozoites. When their host cells die, merozoites get into the blood stream, enter red blood cells and multiply again, infecting new red blood cells in the process.
Meanwhile, some of the merozoites in the blood stream develop into gametocytes, which (after the mosquito bites the infected human again) continue the reproduction cycle inside the mosquito’s digestive tract, by forming an ookinete.
The ookinetes finally develop into new sporozoites, and migrate to the mosquito’s salivary glands, now ready to repeat the entire process again.

What are the symptoms of malaria?

After the mosquito bite, the first symptoms usually appear after one or two weeks. Sometimes it may even take longer than a year, depending on the type of the parasite and its concentration in the blood, as well as the patient's immune status. The first symptoms mostly resemble flu, with patients complaining of fever, sweating, headache, weakness, muscle and joint pain.

As malaria progresses, the patients develop a specific clinical picture, called a malaria paroxysm, which involves three distinct stages:

1. Cold stage, where the patient feels cold and is shivering, while the skin is pale. This may last up one hour, when the rise of body temperature marks the beginning of the second stage.

2. Hot stage, which lasts up to six hours. Besides fever (up to 41°C), muscle pain and headaches are more intense, and the skin is dry. Other symptoms may include:

Lower blood pressure
Increased heart rate
Nausea and vomiting
Irritability and confusion
Enlarged spleen and liver

3. Sweating stage, where the temperature drops, and the patient sweats profusely, feels a little bit better, needs sleep. This lasts up to four hours.

Depending on the type of parasite, this process repeats itself every three or four days, a specific characteristic of malaria. However, in everyday practice, the only positive finding tends to be fever, because other symptoms, such as enlarged spleen, although specific, are rarely diagnosed in early malaria.

Based on the symptoms, malaria can be classified as uncomplicated or severe. An array of complications has been documented, such as:

Cerebral malaria, affecting the nervous system, ranging from confusion to coma
Kidney failure
Low blood sugar levels
Ruptured spleen
Impaired lung function

As you see, malaria can appear in different forms, mimicking all kinds of diseases. Certain populations, such as children, pregnant women, and people living in countries with malaria are more vulnerable, making both the diagnosis and the treatment process more problematic.

How is malaria diagnosed?

The symptoms are rarely clear enough for a diagnosis, so epidemiological data, such as travel history and blood analysis, are used whenever any type of fever of unknown origin appears. However, malaria is typically confirmed under the microscope, where the parasite can be seen inside red blood cells. Quick tests are also available, although they aren’t as precise.

How is malaria treated?

Due to the complicated life cycle of Plasmodium, as well as the variance of parasites and many forms of malaria, there are different groups of medication, called antimalarials. They are used against parasites in the blood (most commonly) or the liver, or to prevent the parasite from infecting the mosquito, thereby blocking further transmission.

Most uncomplicated malaria cases can be treated with quinine, or its synthetic form chloroquine, now in the public eye as a potential therapy for COVID-19. Derived from the cinchona tree and used against malaria as far back as the 16^th century, long before the mechanism of the disease was known, quinine was finally isolated in the 19^th century. It’s highly concentrated in red blood cells, and disrupts the parasites' metabolism by increasing the pH value of the cell.

Another ancient antimalarial, artemisinin, isolated from the Artemisia plant in 1970, is proven to be quick and effective against the parasite in all stages. Numerous other antimalarials, such as Primaquine (useful against liver parasites), atovaquone, proguanil, among many others, can also be used in the fight against malaria.

Treatment depends on several factors, such as the type of Plasmodium, the patient’s age, clinical stability, as well as potential side effects of the drug. Another problem is that in particular areas, parasites have become resistant to some of these drugs. Therefore, treatment demands combination therapy, which your doctor will prescribe according to the situation.

Can malaria be prevented?

Unfortunately, no effective vaccines against malaria currently exist, although some of them are reportedly underway. Arguably, the most effective way to fight malaria is to prevent insect bites, either by using repellents, adequate clothes, or by using mosquito nets. The disease was eradicated in the New World with the help of mass insecticide spraying, smart environmental engineering, hygiene, and drug therapy.

Individuals can prevent malaria by taking antimalarial drugs before and after traveling to a high-risk zone. Institutions should give you more advice on prevention, as well as help you in choosing the right medication. When you return home, you are required to undergo certain heath checks, both because of your own health, and to prevent introducing other infectious diseases often found in tropical climates.

Current status of malaria and possible eradication

Since 2000, there has been a significant decline of malaria deaths, with a rising number of countries reporting fewer cases, although this progress seems to be slowing down. Besides financial issues, growing problems are drug resistance, as well as mosquito resistance to frequently used insecticides. Some scientists have predicted that malaria will be completely eradicated in as quickly as 30 years. However, ongoing funding problems present a huge barrier when it comes to researching new drugs and developing an effective vaccine.

The current COVID-19 pandemic presents yet another challenge, resulting in disruptions related to travel bans, fewer available doctors, lockdowns, lack of drugs, funding, and the general shift of focus from malaria to COVID-19. Unfortunately, we saw something similar during the Ebola crisis a few years ago. Furthermore, there is a concern that the potentially increasing demand for chloroquine may lead to shortages for its original use, rendering those who need it for malaria helpless.

Emerging problems like global warming and mass migration of both humans and animals (including birds and insects) present massive obstacles for the creation of a malaria-free world. Investing into health systems, engineering, and entire health systems is an ambitious idea. Even the World Health Organization argued that it is currently not worth pursuing, because the goals are said to be unrealistic, leading to the conclusion that the whole idea may backfire, resulting only in frustration and astronomical bills.

The presence of well-organized and stable financial and strategic partnering is the key to achieve the goal of eradicating malaria, meaning that the current strategies and principles will have to be changed, especially in a world where every two minutes, a child dies from malaria, and almost half of the entire human population is under direct threat from this horrible disease.