plasmodium parasite Archives

October 18, 2011

Malaria Deaths Fall over 20% Worldwide in Last Decade

There has been a fall of just over 20% in the number of deaths from malaria worldwide in the past decade, the World Health Organization says.

A new report said that one-third of the 108 countries where malaria was endemic were on course to eradicate the disease within 10 years.

Experts said if targets continued to be met, a further three million lives could be saved by 2015.

Malaria is one of the deadliest global diseases, particularly in Africa.

In 2009, 781,000 people died from malaria. The mosquito-borne disease is most prevalent in sub-Saharan Africa, where 85% of deaths occurred, most of them children under five.

An earlier report here incorrectly referred to a 40% drop in deaths.

It has been eradicated from three countries since 2007 – Morocco, Turkmenistan and Armenia.

The Roll Back Malaria Partnership aims to eliminate malaria in another eight to 10 countries by the end of 2015, including the entire WHO European Region.

Robert Newman, director of the WHO’s Global Malaria Programme, said “remarkable progress” had been made.

“Better diagnostic testing and surveillance has provided a clearer picture of where we are on the ground – and has shown that there are countries eliminating malaria in all endemic regions of the world,” he told an international Malaria Forum conference in Seattle.

“We know that we can save lives with today’s tools.”

Global eradication

A global malaria eradication campaign, launched by WHO in 1955, succeeded in eliminating the disease in 16 countries and territories.

But after less than two decades, the WHO decided to concentrate instead on the less ambitious goal of malaria control.

However, another eight nations were declared malaria-free up until 1987, when certification was abandoned for 20 years.

In recent years, interest in malaria eradication as a long-term goal has re-emerged.

The WHO estimates that malaria causes significant economic losses, and can decrease gross domestic product (GDP) by as much as 1.3% in countries with high levels of transmission.

In the worst-affected countries, the disease accounts for: Up to 40% of public health expenditures; 30% to 50% of inpatient hospital admissions; and up to 60% of outpatient health clinic visits.

September 23, 2011October 7, 2011

Malaria Vaccine Trial Raises Hope

By Matt McGrat, Science reporter

Researchers are to expand a clinical trial of a new malaria vaccine after promising results in a preliminary study in Burkina Faso.

The trial was designed to test safety, but researchers found that vaccinated children had high levels of protection.

Described as a “most encouraging” result, a larger study involving 800 children is now to take place in Mali.

The scientists involved say they are hopeful that the vaccine will ultimately be very cheap to produce.

Around a hundred different malaria vaccine candidates have been developed to date but the MSP3 vaccine tested in Burkina Faso is only the second one to show a substantial level of protection against the illness.

The randomised, double blind study involved 45 children. It set out to test the safety of the vaccine but this follow up study found that children who received it had an incidence of the disease three to four times lower than children who did not.

Initially the children were split into three groups, with two of them receiving the experimental malaria vaccine developed by Dr Pierre Druilhe at the Pasteur Institute in Paris.

“Those two groups had very similar types of immune response, elicited by the vaccine, and the protection is almost identical, so it reinforces the confidence despite the fact that we are still dealing with a small group,” he said.

The vaccine is based on the fact that some adults in Africa acquire immunity because they are constantly exposed to the disease.

Early days

Dr Druilhe and his team discovered a key protein, MSP3, which provokes the body into producing antibodies that kill the parasite.

He said the protein is unique as it does not change much between different strains of the plasmodium parasite that causes malaria. This is believed to be a critical factor in developing an efficient vaccine.

He added: “We performed a large number of epidemiological studies that confirm that there was an association between that vaccine candidate and acquired protection, so when you immunise with this molecule you indeed induce protection.”

Another scientist involved with the Burkina Faso study was Dr Louis Miller, the former head of the Malaria Vaccine Branch of the US National Institutes of Health.

He said: “I was always in favour of this approach as it offered a chance in a field with few successes. I found the results of this preliminary study in Burkina Faso to be most encouraging.”

High transmission

Encouraged by the early results, Dr Druilhe said the trial has now been expanded to 800 children in Mali. But he remains cautious.

“There have been too many claims of effective vaccines so we have to remain very cautious. It has to be confirmed and we have started on work to do that confirmation. Essentially the trial in Mali is about 20 times larger, in extremely high transmission conditions, so it should yield very clear cut results – this will be black and white.”

The other vaccine candidate that has shown success against malaria is called RTS, S. It has been funded by the Bill and Melinda Gates Foundation and is set to go into production with pharmaceutical giant, GlaxoSmithKline.

But there are concerns that it could be expensive, especially for people in Africa and other regions affected by the disease.

Dr Druilhe says his vaccine could be a lot cheaper – perhaps half a dollar or less a bottle.

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The results of the Burkina Faso trial were published in The New England Journal of Medicine.

April 25, 2011April 28, 2011

Using Mosquitoes To ‘Vaccinate’ Against Malaria

Joanne Silberner,NPR

The parasite responsible for the intense fevers, chills, and headaches of malaria is very skilled at hiding in the in the body. That means vaccines don’t work all that well to prevent the disease.

So Dutch researchers are trying a new approach — “vaccinating” people by having them get bitten by mosquitoes carrying the malaria parasite, which is similar to how people get infected in the real world. And it seems that this technique may keep people safe from the disease more than two years later.

The Dutch way is different than the conventional vaccine approach of injecting people with bits and pieces of the malaria parasite, or a parasite that’s been weakened in the lab.

Those traditional approaches haven’t been working all that well in clinical trials. The Plasmodium parasite is notoriously tough to manipulate because it spends most of its time hiding inside red blood cells and liver cells, out of sight of the immune system. That’s one reason why it was able to kill 781,000 people in 2009. Most of those were children in developing countries.

In the Dutch experiment, 10 volunteers were bitten multiple times by malarious mosquitoes. The researchers then gave the volunteers an anti-malaria drug, chloroquine. (And yes, the researchers were very careful to pick a malaria type that can be vanquished by chloroquine, not a variety resistant to the drug.)

A couple of years ago, the researchers reported that this process works in the short run to protect against malaria. But that’s not such a big deal. People naturally infected by malaria build up an immunity that holds for several months.

What’s new is that the researchers went back to six of the volunteers 28 months later. Once again the volunteers allowed themselves to be bitten by malarious mosquitoes. Four of the six did not get infected. And the immune systems of the remaining two put up a fight – their infections were delayed (and quickly treated). The results were published online in The Lancet.

Wondering who would volunteer to be bitten by a malarious mosquito? Study author Robert Sauerwein of Radboud University in the Netherlands says most were university students. And the trial was designed pretty carefully.

A lot more work needs to be done to test this approach. This study was very small – only six people. And the researchers note that they may have stacked the deck a little – they used the exact same strain of malaria to infect, and to re-infect. And they worked with adults with mature immune systems, rather than children.

It’s not clear yet why the experimental vaccination protected longer than infection by mosquito in the field. The anti-malarial drug could have helped. Or maybe it was the intense exposure to multiple bites at the same time. Whatever the reason, they say, it’s worth investigating given how well the malaria parasite has been at outsmarting attempts to get rid of it.

October 11, 2010January 21, 2011

A Breakthrough in Malaria Research

Scientists from Scotland have reported a major breakthrough in fight against malaria.

The team from Edinburgh University in collaboration with a team in Portugal have discovered a gene that offers the drug resistance trait to the parasite. Drug-resistant plasmodium falciparum parasites are a major hindrance in the battle against the deadly disease. Chloroquine, the most commonly prescribed medicine against malaria has lost its effectiveness due to the proliferation of chloroquine resistant parasites.

Scientists think this is a major development in malaria research. Malarial kills one to three million people annually, mostly children. These findings may pave a way for a new class of anti-malarials.

The study has been published in Biomedical Central (Sept 2010)