by Daniel Ooko and Zhao Zhuoyun
NAIROBI, Nov. 5 (Xinhua) -- Scientists gathered at the world's largest malaria conference are debating on Thursday the challenge of malaria drug and insecticide resistance and call on researchers and policymakers to act urgently to contain the problem.
The experts said the threat of the failure of frontline tools for malaria control and treatment, treated bednets, insecticides, and artemisinin combination therapies (ACTs), could leave millions of people vulnerable to the disease, with little recourse for prevention or effective treatment.
This could reverse the massive gains achieved with these tools over the last five years.
Staying one step ahead of the malaria parasite, which constantly evolves to become resistant to malaria drugs, will require redoubling the efforts to develop new classes of effective medicines.
Speaking on the sidelines of the Pan-African Malaria Conference, Head of Disease Prevention and Control at the Kenyan Ministry of Public Health Dr. Willis Akhwale requires about 7.5 billion shillings (100 million U.S. dollars) annually to eliminate the killer disease in the next seven years.
He however said that even if resources were made available, there would be need to change the strategies used.
"We are at a place where we are controlling the disease and we now want to move to the next phase," Akhwale said, "Now we know the tools that work (but) the access to these tools have remained limited."
"For example with bed nets we have just been targeting children and pregnant women. In the next phase we want to have universal coverage; we want every household to have at least two nets," he added.
Researchers said artemisinin is the most effective front-line drug against malaria in the world today. It was recommended as the first-line therapy by the World Health Organization (WHO) in 2002 and has saved millions of lives since then.
However, resistance to this life-saving drug is emerging. Some studies published in 2008-2009 reported a doubling of the time to clear the parasite from the blood in some malaria patients in the western region of Cambodia.
However, efficacy at 28 days was maintained, and the patients were still cured with the ACTs they had been given.
This "resistance", first observed in West Cambodia, has now also been reported in the west of Thailand and in eastern Myanmar.
But it has not yet been possible to ascertain if this additional "resistance" is due to the Cambodian strains or to different strains.
DHA/PQP (Eurartesim), a new ACT developed by Sigma Tau and Medicines for Malaria Venture (MMV), and recently submitted to the European Agency EMEA, will also be submitted to the regulatory authorities of Cambodia.
The drug could be used for the containment of the strains resistant to artemisinin, if requested by the WHO and the government of Cambodia.
In addition, a new generation of drug combinations is under development that could one day replace ACTs.
Bednets and indoor spraying are the cornerstones of malaria control, having saved millions of lives, and yet they are entirely dependent on mosquito populations remaining susceptible to insecticides.
Bednets are especially vulnerable, as pyrethroids are the only class of insecticides currently available for bednets. If pyrethroid resistance becomes widespread, this vital barrier against infection will be lost.
The ramping up of control programs will increase pesticide use, and the spread of resistance to all classes of insecticides could become inevitable.
High levels of pyrethroid resistance have already been detected in west and southern Africa, and it appeared that this is already having an impact of the effectiveness of bednets.
Akhwale said they were in the process of reviewing a policy where the Artemisinin based combination treatment (ACT) which is currently only available on prescription can now be accessed at community level.
He said the ministry would then target at the locations with limited transmission, but with large geographical areas.
"For example in the semi-arid north we will start thinking of where transmission is highly seasonal and we may think of mass drug administration as one particular strategy that we may employ," Akhwale said.
"But in Coastal and Western parts of this country where the prevalence is still very high, we believe that by 2017 we will have moved to the pre-elimination phase," he said.
The insecticide research and development pipeline will likewise need to be filled with new active ingredients that malaria-carrying mosquitoes have not yet learned to tolerate.
New insecticides that work in an entirely different way to current classes are therefore urgently needed to ensure that the expansion of control efforts does not result in a total failure of one of the only weapons against mosquitoes.
The International Vector Control Consortium (IVCC) is working in partnership with major chemical companies to develop new active ingredients.
Their partners were using data mining programs to find development candidates for these new active ingredients within their extensive chemical libraries.
Developing entirely new insecticides takes a great deal of time and hundreds of millions of dollars, but it is crucial that the global community act now to prevent the failure of control programs and avert a new public health catastrophe in the developing world. In the meantime, careful and judicious use of the current insecticides is strongly advised.
Prof. Pedro Luis Alonso, chairman of the Board of Governors of Manhica Health Research Center in Mozambique, said although Africa was geared towards malaria eradication, the present strategies like the use of treated bednets and ACT drugs may not be adequate because of the cases of resistance.
"When we say eradication, I am not sure we have been able to get across the concept and the history. There is just one disease in the history of mankind that has been eradicated and this was small (which) a reasonably easy disease is, and we had a phenomenon tool which was a vaccine," Alonso said.
He said malaria is much more difficult and complex than any of these other diseases.
