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A brief primer on malaria
Malaria is an infectious disease that occurs mainly in the tropical and subtropical countries of Middle America, Sub-Saharan Africa and Southeast Asia. Both residents and tourists are at permanent risk of contracting it. The Malaria causing parasite is transmitted to humans by the Anopheles mosquito. The infection leads to flu-like symptoms – high fever, headaches, joint pain and sometimes vomiting and diarrhea in addition. Three types of Malaria are known. The most feared is Malaria tropica, which is often linked to severe complications, organ failure and death. The others are Malaria tertian and Malaria quartana, which typically exhibit less severe disease progression. However, in patients with weak immune systems, even they can become life-threatening.
Roughly 1,200 people die from Malaria each day. That equates to more than 400,000 deaths per year. Even though Malaria fatalities have stagnated since 2013, the number of infections rose by five million to a total of 216 million in 2016.
A mosquito is the disease carrier – the true culprits are others…
Malaria is induced by Plasmodium parasites which use Anopheles mosquitoes as a host. When biting a human, the mosquito transmits thousands of parasites with its saliva. Plasmodium colonizes liver and red blood cells in the human body for asexual propagation via cell maturation and division. As soon as another mosquito bites the infected person, the Plasmodium back-infects the Anopheles via the human blood. In the mosquito’s digestive track, sexual propagation gametocytes develop from the up-taken Plasmodium cells. Recent studies have even shown that perspiration from Malaria victims includes a special volatile component that attracts further mosquitoes – a quite effective way of supporting the Plasmodium development lifecycle. There are five well understood Plasmodium species that are dangerous for humans, P. falciparum, P. malariae, P. ovale, P. vivax and P. knowlesi. Depending on the Plasmodium species, the disease brakes out after an incubation period of 7 to 50 days.
However, a mysterious Malaria outbreak was reported in Brazil between 2015 and 2016. More than two dozen people were infected with P. simium, a Plasmodium species that usually attacks New World monkeys only. Malaria experts now fear a sixth human pathogenic species.
How to heal
One of the most common medicines for treating Malaria is quinine, which was already used in the 17th century. According to tradition, colonists in British Africa used to drink tonic water containing quinine as a Malaria prophylaxis. To cover the very bitter taste of quinine, they mixed it with gin, thus giving birth to the still-popular gin & tonic cocktail. The second class of Malaria drugs contains artemisinin, a plant component of the mugwort. To address the high demand for artemisinin to cure Malaria, scientists around the world are working on new breeds and transgenic solutions to create mugwort with higher drug content. Plasmodium can adapt rapidly however. Increasing resistance to medications is hampering the fight against this tropical disease.
There is currently no vaccination available against Malaria. After decades of research and development, only a few candidates are in clinical testing. The only way to protect against infection is to take proper prophylactic measures. Apart from medicines for chemoprophylaxis, the best way to ward off Malaria infections is the use of mosquito nets, insect repellents and protective clothing.
The great unknown
Although Malaria has been known for hundreds of years, it is still not fully understood. Even today, new correlations are being uncovered and changing characteristics are being identified. Several weeks ago for instance, a study was published by scientists who discovered that Plasmodium vivax accumulates in the bone marrow, a completely new finding. The markers they used for detection could be a blueprint for advanced Malaria diagnostic tools. Meanwhile, physicians in Germany, Italy, Spain and Greece have observed a new method of transmission. At least six people were infected with Malaria without any contact with a mosquito. The only logical explanation is that the infection was passed between humans since all of the victims were in contact with Malaria patients. No comparable form of transmission has been described to date.
Malaria experts agree that there is still much to be learned and done, but the battle has not been lost. The bottom line is, the efforts will continue to eradicate Malaria by 2030, much like has already been done in Sri Lanka and Vietnam.