WHAT'S NEW THIS SUNDAY: THREE ON MALARIA

Saturday, 28th of July 2012

• THREE ON MALARIA
• AFRICA MONEY--WAKING UP TO THE MATHS OF MALARIA

By Ed Cropley

JOHANNESBURG, June 21 (Reuters) - To the minerals and mobiles underpinning Africa's pacy growth over the last decade, you may soon be able to add malaria - or at least its absence.

Besides the huge human cost imposed on the continent - 90 percent of the 655,000 deaths estimated worldwide in 2010 - the mosquito-borne disease is an economic millstone, draining public and private resources and hammering productivity.

According to a 2001 study co-authored by U.S. economist Jeffrey Sachs, the disease imposes an annual "growth penalty" of 1.3 percentage points on afflicted states, which includes most of those south of the Sahara apart from South Africa.

In Nigeria, Africa's most populous nation and its biggest oil producer, malaria is responsible for up to 25 worker days lost per person per year, or two a month, due to direct infection or the need to stay at home to nurse a sick family member, often for a week or more.

In Zambia, it is the leading cause of absenteeism, accounting for more than twice as many days off as HIV/AIDS, and can consume up to 40 percent of the public health budget in cash-strapped frontline states.

It may not always be thus.

The number of malaria deaths has fallen dramatically in the last decade due to increased aid spending on basic items such as insecticide-treated bed nets and drugs, the World Health Organization (WHO) says.

More excitingly, the holy grail of a vaccine against a notoriously adaptable parasite no longer appears unobtainable after an experimental vaccine from GlaxoSmithKline was shown last year to halve the risk of African children getting the disease.

Even before the prospect of a vaccine, companies across Africa were waking up to the commercial sense of investing in a malaria-free workforce - and the results are encouraging governments to get in on the act.

Faced with endemic malaria in the 240,000 population town around its Obuasi gold mine in Ghana, AngloGold Ashanti , the world's third largest bullion producer, launched a multi-pronged campaign of bed-nets, indoor insecticide spraying and drugs that cut infections from 79,237 in 2005 to fewer than 16,000 in 2008.

The programme cost the Johannesburg-based firm $1.3 million a year, but over that time the malaria drug bill at the mine's hospital dropped from $55,000 to $9,800 a month, while work days lost each month fell from 6,983 to just 282.

"It really made economic sense because of the absenteeism and the cost of medication," said Steve Knowles, the head of AngloGold's anti-malaria operations.

The Ghana model is now being extended to commmunities around its mines in Democratic Republic of Congo, Tanzania, Mali and Guinea, bringing as many as 500,000 people under its umbrella.

Europe's financial crisis and relatively sluggish rich-world growth have left a question mark over cash pools such as the Global Fund to Fight AIDS, Tuberculosis and Malaria that have been complementing state and private sector efforts, threatening to unravel the gains made.

But Knowles said many governments were becoming increasingly aware of the mathematics of beating malaria and starting to put their own programmes in place.

The prospect of an affordable vaccine is only going to increase the power of that argument for a region forecast to grow at 5.4 percent this year - even with malaria. Without it, that figure could be knocking on 7 percent.

"Now that they're seeing the aid funding may not be there, it's a bit of a wake-up call and governments are looking to do it themselves," Knowles said. "What difference will a vaccine make? If it comes through, it's going to be huge." (Editing by Ed Stoddard and Ron Askew)

• IDENTIFICATION OF A NEW CHEMICAL CLASS OF ANTIMALARIALS

Abstract below; full text available to J Infect Dis subscribers

J Infect Dis. (2012)

First published online: June 25, 2012

Identification of a New Chemical Class of Antimalarials

Ralf Brunnera,b, Hamed Aissaouic, Christoph Bossc, Zbynek Bozdechd, Reto Bruna,b,

Olivier Corminboeufc, Stephane Delahayec, Christoph Fischlia,b, Bibia Heidmannc, Marcel Kaisera,b,

Jolanda Kambera,b, Solange Meyerc, Petros Papastogiannidisa,b, Romain Siegristc, Till Vossa,b,

Richard Welfordc, Sergio Wittlina,b and Christoph Binkertc

- Author Affiliations

1.    ^aMolecular Parasitology & Infection Biology, Swiss Tropical and Public Health Institute, CH-4002 Basel, Switzerland

2.    ^bUniversity of Basel, CH-4003 Basel, Switzerland

3.    ^cDrug Discovery Chemistry & Biology, Actelion Pharmaceuticals Ltd, CH-4123 Allschwil, Switzerland

4.    ^dSchool of Biological Sciences, Nanyang Technological University, 637551 Singapore

1.    Correspondence: Christoph Binkert, E-mail: christoph.binkert@ext.actelion.com, Telephone: +41 61 565 6541, Fax: +41 61 565 8902

Abstract below, also at http://jid.oxfordjournals.org/content/early/2012/06/23/infdis.jis418.abstract?etoc

The increasing spread of drug-resistant malaria strains underscores the need for new antimalarial agents with novel modes of action (MOAs). Here, we describe a compound representative of a new class of antimalarials. This molecule, ACT-213615, potently inhibits in vitro erythrocytic growth of all tested Plasmodium falciparum strains, irrespective of their drug resistance properties, with IC₅₀ values in the low single-digit nanomolar range. Like the clinically used artemisinins, the compound equally and very rapidly affects all three asexual erythrocytic parasite stages. In contrast, microarray studies suggest that the MOA of ACT-213615 is different from that of the artemisinins and other known antimalarials.

ACT-213615 is orally bioavailable in mice, exhibits activity in the murine P. berghei model and efficacy comparable to that of the reference drug chloroquine in the recently established P. falciparum SCID mouse model.

ACT-213615 represents a new class of potent antimalarials that merits further investigation for its clinical potential.

• AIR FLOW AND BED NET USE

‘Thermal discomfort is a factor limiting bednet use.’

Airflow attenuation and bed net utilization: Observations from Africa and Asia

Lorenz von Seidlein, Ikonomedis Konstantin, Rasmus Bruun, Musa Jawara, Margaret Pinder, Bart GJ Knols and Jakob B Knudsen 

Malaria Journal 2012, 11:200 doi:10.1186/1475-2875-11-200

Published: 15 June 2012

Abstract (provisional)

Background/Methods Qualitative studies suggest that bed nets affect the thermal comfort of users. To understand and reduce this discomfort the effect of bed nets on temperature, humidity, and airflow was measured in rural homes in Asia and Africa, as well as in an experimental wind tunnel. Two investigators with architectural training selected 60 houses in The Gambia, Tanzania, Philippines, and Thailand. Data-loggers were used to measure indoor temperatures in hourly intervals over a 12 months period. In a subgroup of 20 houses airflow, temperature and humidity were measured at five-minute intervals for one night from 21.00 to 6.00 hrs inside and outside of bed nets using sensors and omni-directional thermo-anemometers. An investigator set up a bed net with a mesh size of 220 holes per inch2 in each study household and slept under the bed net to simulate a realistic environment. The attenuation of airflow caused by bed nets of different mesh sizes was also measured in an experimental wind tunnel.

Results

The highest indoor temperatures (49.0 C) were measured in The Gambia. During the hottest months of the year the mean temperature at night (9 pm) was between 33.1 C (The Gambia) and 26.2 C (Thailand). The bed net attenuated the airflow from a minimum of 27% (Philippines) to a maximum of 71% (The Gambia). Overall the bed nets reduced airflow compared to un-attenuated airflow from 9 to 4 cm sec-1or 52% (p < 0.001). In all sites, no statistically significant difference in temperature or humidity was detected between the inside and outside of the bed net. Wind tunnel experiments with 11 different mesh-sized bed nets showed an overall reduction in airflow of 64% (range 55 - 71%) compared to un-attenuated airflow. As expected, airflow decreased with increasing net mesh size. Nets with a mesh of 136 holes inch-2 reduced airflow by 55% (mean; range 51 - 73%). A denser net (200 holes inch-2) attenuated airflow by 59% (mean; range 56 - 74%).

Discussion

Despite concerted efforts to increase the uptake of this intervention in many areas uptake remains poor. Bed nets reduce airflow, but have no influence on temperature and humidity. The discomfort associated with bed nets is likely to be most intolerable during the hottest and most humid period of the year, which frequently coincides with the peak of malaria vector densities and the force of pathogen transmission.

Conclusions

These observations suggest thermal discomfort is a factor limiting bed net use and open a range of architectural possibilities to overcome this limitation.

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