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TIPS ON MALARIA

  • HOW CAN MOSQUITOES BE CONTROLLED?

    Mosquitoes around the home can be reduced significantly by minimizing the amount of standing water available for mosquito breeding. Residents are urged to reduce standing water around the home in a variety of ways.

  • HOW CAN I PROTECT MYSELF FROM MOSQUITO-BORN DISEASES?

    The best way is to avoid being bitten by mosquitoes.This can be accomplished using personal protecting  while outdoors when mosquitoes are present. Treated bed nets should be used sleeping. Mosquito repellent should be used when outdoor.

  • WHO ARE AT RISK?


    Nearly half of the world’s population is at risk of getting malaria. Pregnant women are particularly at risk of malaria. Children under 5 years are at high risk of malaria.
     

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The last parasite standing

Malaria fighters have labelled Plasmodium vivax, “the last parasite standing” due to its persistent survival in the face of a massive global campaign to eliminate it.

With its unique ability to relapse by hiding in the liver for months or even years, vivax is harder to detect and cure and there is mounting evidence that vivax malaria may be killing far more people than previously thought.
 
Researchers unveiled a new malaria map that was the first to identify on a global scale the long-lasting and potentially deadly vivax which has a firm foothold in large parts of South Asia and parts of Latin America.

“This map helps us understand just how difficult it is going to be to eradicate malaria” said Peter Gething who led the University of Oxford’s Malaria Atlas Project (MAP) team that produced the study of the vivax burden.

“It shows that in substantial parts of the world, vivax malaria is endemic and transmission is significant. Unfortunately, the tools for fighting this type of malaria range from the ineffective to non-existent”, Gething added.

While not as deadly as the Plasmodium falciparum malaria parasite that is predominant in Africa, vivax is more common throughout the world with an estimated 2.85 billion people at risk of infection.

Meanwhile, bed nets and indoor spraying together with Artemisinin combination therapies (ACTs) which have helped reduce malaria deaths in Africa appear to have had little impact on vivax.

One reason is that the mosquitoes that transmit vivax typically bite outdoors, rather than indoors in the home.

This has caused some concern among experts about the fact RTS,S malaria vaccine candidate which will be available soon, offers no protection against vivax.

Disturbing data
Dr J. Kevin Baird, who works with the Eijkman-Oxford Clinical Research Unit in Jakarta, Indonesia, said identifying hotspots for vivax infections was crucial because it is becoming increasingly clear that vivax malaria was more of a threat than previously believed.
 
Just a few years ago, he said, the prevailing view of vivax was that it routinely gave patients soaring fevers and severe chills but was rarely fatal.

“We are beginning to suspect that plasmodium vivax is killing people at far higher rates than anyone, including malariologists, thought even remotely possible, Baird said.

“We still have very little data on this issue, but what data we do have worries me a great deal”.

For instance, Dr Baird presented a new study at the ASTMH that examined the outcome of patients admitted to a hospital in eastern Indonesia with a diagnosis of malaria.

He and his colleagues at Jakarta Eijkman Institute found vivax malaria to be the likely cause of both severe illness and deaths. Also for malaria patients classified as severely ill, the risk of death was the same regardless of whether they had vivax or falciparum malaria.

Another study conducted in Indonesia reported similar findings. Researchers at Australia’s Menzies School of Health Research investigated 65 deaths at a single hospital over a five-year-period that was linked to vivax malaria. They found that in this group of patients, vivax was more often a contributing factor to the deaths rather than the sole cause. But the scientists believe it is important to consider how infections with the vivax parasite may be an ‘important indirect cause of death” in patients already suffering from debilitating conditions such as malnutrition, sepsis and HIV, which are all common in malaria-endemic regions.

Ric Price, a malaria researcher at Menzies and a co-author of the study said, it was difficult to state with confidence how many people are dying of vivax because so many malaria patients also have other illnesses.

Hotspots of vivax
Hotspots for vivax malaria highlighted by MAP include substantial parts of India. Rates are high even in urban areas like Mumbai, where malaria once thought of largely as a disease of rural areas, was previously uncommon. Papua New Guinea also has a high rate of infections and transmissions, as do significant parts of Indonesia and Myanmar (including Yangon). In the Americas, the area of greatest concern is a large but sparsely populated portion of the Northern Amazon, most of which is in Brazil. But the hotspot also includes parts of Peru, Colombia and Venezuela. In Central America, almost all of Nicaragua is a hotspot for vivax malaria, as are parts of Honduras and Guatemala.

In Africa, Dr Gething said while vivax is known to exist, infection rates appear to be “very, very low” for most of the continent, though the map indicates a moderate but stable level of vivax transmission in parts of the Horn of Africa and throughout Madagascar.

Large reservoir of vivax infections
Researchers considered an area to be a vivax hotspot if the data analysis yielded infection rates that exceeded seven per cent.

Dr Gething noted that this threshold might be considered relatively low for falciparum infections. But he said it is high for vivax in part because the figure accounts only for parasites that are detectable in the blood, and also because vivax disease rates have proven hard to reduce.

He noted that in areas where vivax was endemic, at any given time, there were many people carrying vivax parasites only in their liver, from which they periodically emerge to cause new infections in the bloodstream. But he said, this ‘large reservoir’ of vivax is difficult to quantify with existing surveillance tools, chiefly because there is currently no simple test for detecting the liver parasites.

“One person with vivax actually can represent multiple malaria infections over many years in a single community and each time the parasite moves from the liver to the blood, it contributes anew to disease burden and transmission” Dr Gething said.

According to him, the disease burden caused by vivax relapse is exacerbated by a lack of treatment options. Medicines such as the ACTs that are used to cure falciparum infections can help treat acute bloodstream vivax infections. But only one drug – primaquine – can clear vivax parasites from the liver and thus provide a long term cure to this type of malaria.
Genetic twist of fate However, in a cruel twist of evolution, a hereditary condition that may have evolved in response to malaria exposures can make the drug toxic, sometimes fatally so, to some people who live in vivax-endemic areas.

Alternatives for primaquine
Researchers agree that controlling vivax in areas where it remains endemic requires vastly improved interventions.

Researchers at the meeting presented efforts to find alternatives to primaquine i.e. drugs that can kill liver-stage parasites without the toxic side effects.

Also discussed were the efforts to develop a vaccine against vivax malaria. The first vivax vaccine candidate supported by the PATH. Vaccine experts note that vivax poses a  particular challenge because it has parasites that exist in the bloodstream and in a dormant phase in the liver.

Protection for travellers
One important issue arising from the discussion of vivax prevalence and severity is the extent to which travellers should take precautions when visiting areas where vivax malaria is known to exist at any level.

Travellers heading for regions where vivax transmission occurs should consider taking primaquine as long as they are not pregnant and do not carry the genetic trait that can render the drug toxic.
 
Call to action
Malaria experts say even though vivax still appears to be less deadly than falciparum, growing evidence of its link to fatalities warrant giving it a higher profile in the global malaria eradication campaign.

-By Rebecca Kwei, Ghana

Editions: 
Tenth Edition