Day: 09/27/2010

Gorillas spread malaria to humans, say scientists

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gorilla_Flickr_nouQraz.jpgMalaria culprit? Gorillas — rather than bonobos or chimpanzees — may have spread the disease to humans

Flickr/nouQraz

Gorillas are likely to have been the original source of malaria in humans, and the parasite probably jumped across the species about 5,000 years ago, say scientists, who will begin screening humans living near gorillas to see if the parasite is still moving between the populations today.

An international team of scientists working in Cameroon, Central African Republic and the Democratic Republic of Congo (DRC), has shown that the parasite Plasmodium falciparum, which causes the most dangerous form of malaria, probably made a single jump from gorillas — not bonobos or chimpanzees as previously thought.

The discovery could influence the understanding of malaria in the same way that comparisons of the biology of HIV with its equivalents in apes have given scientists greater insight into the mechanisms behind the disease.

The team, whose work is published in Nature today (23 September), collected thousands of samples of ape faeces to screen for malaria parasites.

“By studying the closest relative to human P. falciparum in gorillas, I cannot imagine that this would not give important clues as to why the human parasite is so pathogenic [disease-causing],” lead researcher Beatrice Hahn, a professor at the University of Alabama at Birmingham (UAB), United States, told SciDev.Net.

Jean-Bosco N. Ngona, co-author of the study and a scientist at the University of Kisangani, DRC, said that more work is needed to understand whether there are malaria interactions between gorillas and humans today.

“It would give you a heads-up of what there might be to come,” said Hahn. “As future eradication efforts bear fruit, you could generate a niche for a new parasite to move in.”

Nathan Wolfe, director of the Global Viral Forecasting Initiative (GVFI), said the work was a “great finding … we need to think about the possibility that some of these parasites might be entering the human population”.

Such movements could go undetected in the developing world, he said, where diagnosing the presence of the malaria parasite is done by looking at its structure and shape rather than its genes.

“It’s very likely if any of these other parasites was found in a human it would be misdiagnosed as P. falciparum,” he said.

source:Nature

TB vaccine likely to be five years late, says review

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[TALLIINN, ESTONIA] A vaccine for tuberculosis (TB) is unlikely to be ready until 2020, say scientists, who will revise the original target from 2015 in a report to be published next month.

A mid-term review of the ‘Global Plan to Stop TB 2006–2015’, which will be released after a meeting in Johannesburg, South Africa, next month (14-15 October) says that the 2015 goal was “optimistic”, and predicts a bottleneck when it comes to carrying out later stage clinical trials.

The global plan was drawn up by the Stop TB Partnership and various stakeholders in 2006, and outlines a ‘big picture’ approach to tackling TB worldwide.

“It was unreasonable to claim to have the TB vaccine by 2015,” said Michel Greco, chair of the Stop TB Partnership Working Group on New TB Vaccines. “If we have a valid vaccine produced by 2020 that will be a feat.”

“2015 was too optimistic,” Hassan Mahomed, clinical director of the South African TB Vaccine Initiative, told SciDev.Net, adding that “somewhere between 2016 and 2020 is a bit more realistic”.

The scientists were speaking on the sidelines of the Second Global Forum on TB Vaccines, in Tallinn, Estonia this week (21-24 September), where they are putting together a detailed blueprint for the development of vaccines against the disease.

TB research has yielded 13 new vaccines, the most advanced of which will be ready for phase III trials in 2013. But scientists fear it will be difficult to find sites for these trials where the incidence of TB is high enough for the trials to be executed quickly.

Although TB is one of the most serious diseases in the world, with over nine million new cases each year and 1.8 million deaths, it is widely spread. This makes it hard to find a site where there are sufficient infections occurring for the protective effects of a vaccine to be easily detected.

Helen McShane, vaccinologist at Oxford University, United Kingdom, whose team is working on the most advanced vaccine candidate so far, told SciDev.Net that the highest incidence they have found at potential trial sites has been three per cent over a period of two years — the equivalent of only three people infected per 100 tested during a whole two-year trial.

Such an incidence would require a trial of about 40,000 people in order to adequately compare vaccinated and placebo groups.

McShane added that Phase III trials on TB vaccines, in their current form, may never be possible, and new approaches may be needed, such as modelling a trial instead.

A second impediment will be the lack of skilled capacity for conducting large-scale trials, and the lack of basic infrastructure, said Greco.

Keeping that capacity going between trials will be an even bigger challenge, he added.

FDA OKs Combination Contraceptive with Folate

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The FDA has approved Beyaz, a combination oral contraceptive containing a folate to prevent neural tube defects.

Beyaz will contain the same doses of progestin and estrogen as the oral contraceptive Yaz. Both are made by Bayer.

Like Yaz, Beyaz is approved to prevent pregnancy, treat symptoms of premenstrual dysphoric disorder, and treat moderate acne. In addition, it is indicated to raise folate levels in women taking oral contraceptives. A clinical trial found that women’s folate levels stayed elevated several weeks after they stopped taking the drug. The efficacy and side effects were essentially unchanged compared with Yaz.