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Different Types of Malaria, Geographic Dispersal, Risk Assessment, and How Travelers Can Prepare

Plasmodium vivax malaria prevalence worldwide
Plasmodium vivax malaria prevalence worldwide
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There are four types of malaria that humans can acquire — Plasmodium falciparum, P. vivax, P. ovale, and P. malariae — which carry their own levels of severity, illness, and fatality rates. Plasmodium falciparum is the most dangerous type, and is often the reason why people mutter the word “malaria” with fear. The others are very rarely life threatening, but can cause rather severe illness and some have the possibility of relapse. As there are different risks inherent to each form of malaria, travelers should know what types of malaria are present in the regions they are going to. All forms of malaria often get lumped together with P. falciparum — the worst type — under a single broad banner. Vagabondjourney.com believes this is an error, and travelers should view the various types of malaria as similar but separate afflictions, and decide on taking a prophylaxis, just carrying a supply of meds designed to combat the disease, or not preparing medically at all accordingly.

Plasmodium vivax is the most prevalent type of malaria worldwide, and is the most common cause of recurring (tertian) malaria, but its fatality rate is extremely low. As research and prevention of the more deadly P. falciparum type of malaria often receives up to 97% of available funding for this disease, the other types of malaria have been kept on the medical back burner so to speak. Researchers at the Malaria Atlas Project say that this is a huge mistake, and have recently put together data from around 8,000 surveys of infection prevalence to construct a map of the world which shows the areas where people are at highest risk of catching the P. vivax type of malaria.

Like the more dangerous Plasmodium falciparum, Plasmodium vivax is transmitted from the bite of a female anopheles mosquito. As she feeds, parasitic sporozoites (spores) are injected into the body along with blood clot inhibiting saliva. Within a half an hour the parasite sporozoites are received by the liver, where they make camp and asexually reproduce in hepatic cells. Thousands of malarial parasites are soon created and passed around the liver and circulatory system where they grow and mature. Eventually, P. vivax penetrates immature red blood cells, which causes them to double in size and become severely disfigured. The parasite will then begin to reproduce sexually inside the cell. The incubation period is generally 10 to 17 days, but sometimes takes up to a year. Relapses can occur up to five years later.

Like other types of malaria, symptoms of P. vivax include fevers, chills, headaches, vomiting, and diarrhea. One of the biggest complications of this type of malaria is that it can enlarge the spleen, but, in the end, it is rarely ever fatal. Chloroquine and primaquine are usually applied in tandem get rid of the parasite and decrease the chances of recurrence, but one major problem with P. vivax is that it is becoming increasingly resistant to these drug treatments and prophylaxis.

Maps of P. falciparum and P. vivax worldwide prevalence

Plasmodium falciparum (potentially fatal) malaria map

Plasmodium vivax prevalence worldwide

As you can see from the maps, P. falciparum, the deadly form of malaria is concentrated in highest amounts in Africa, India, and select strips of Southeast Asia, while P. vivax has highest prevalence in Central America, the Amazon, India, and Southeast Asia.

How this information helps travelers

Popularly proscribed malaria prophylaxis, such as Mefloquine and Doxycycline, are harsh drugs with their own particular blend of side effects. From experience, taking these drugs regularly over long periods of time carry their own risks.

Doxycycline is an antibiotic that is often proscribed for infections involving the skin and eyes. It also works as a cheap malaria prophylaxis. The problem is that it makes the skin of the user severely photo-sensitive, resulting in chemical burns if exposed to too much sunlight. There is a sever conflict of interests here as many malaria areas of the world typically have hot climates with high amounts of direct sunshine. From our experience, it is not too comfortable going around on 100+ degree days in the tropics in a long sleeve shirt, hat, and pants.

Though the effects of Doxycycline may be preferable to those of Mefloquine, which seems to be the American doctor’s first string malaria prophylaxis. This is a very expensive drug — $10+ per pill — which can cause neuropsychiatric disorders and other mental health problems, such as anxiety, depression, hallucinations, vivid dreams, dizziness, insomnia, suicidal tendencies, and unusual behavior in 11-25% of users. This is a harsh drug that is often used to cure malaria, and taking it for long periods of time — such as in extended bouts of tropical travel or when living in these regions — can tip the benefit/ risk ratio as to whether it should be used or not.

Malaria is often spoken of as a singular affliction in doctor/ patient consultations. In our experience it is rare that a doctor — even one at a travel clinic — explains to patients that there are actually multiple forms of Malaria in different parts of the world with varying levels of prevalence and risk, and then advises their patients accordingly as to whether or not they should take a prophylaxis. No, from the experience of vagabondjourney.com and that of many other travelers who have reported to us, doctors at travel clinics simply say, “There is malaria where you’re going, you need a  prophylaxis,” and then proscribe meds which could have harsh side effects and are often incredibly expensive.

In point, P. falciparum, the deadly form of malaria, is only highly prevalent in pockets of Africa, India, and SE Asia. Even in the heart of Africa, 85% of the people who acquire this form of malaria are under 5 years of age. While it is true that the other non-lethal forms of malaria — namely P. vivax — are not a cakewalk to recover from by any means, whether or not to regularly take a harsh medication to prevent against catching them is a matter that should be considered by each individual traveler. It is the traveler’s personal decision as to whether or not to take a prophylaxis when in malarial regions — not a doctor’s or a travel clinic nurse who just repeats verbatim CDC recommendations — and the true risks involved can easily be assessed.

Superimpose your projected travel itinerary over maps which show the prevalence rates for the various types of malaria, decide if taking a potentially harsh prophylaxis outweighs the potential risks associated with the type of malaria you may be exposed to, and take action accordingly. Not all malaria is the same, and the bulk of medical research and prevention strategies are set up for the most deadly variant, P. falciparum — which is only highly prevalent in certain parts of the malarial world. Keep this in mind when making your decision.

For more information on the global dispersal of malaria visit the Malaria Atlas Project. For more on the various types of Malaria and their inherent risks access the vast array of resources available online.

*This article omits the P. ovale and P. malariae types of malaria as they are comparatively rare and more mild than their cousins, and treatment is similar.

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Filed under: Health

About the Author:

Wade Shepard is the founder and editor of Vagabond Journey. He has been traveling the world since 1999, through 76 countries. He is the author of the book, Ghost Cities of China, and contributes to Forbes, The Diplomat, the South China Morning Post, and other publications. has written 3054 posts on Vagabond Journey. Contact the author.

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