ACTs may achieve malaria transmission reductions comparable to insecticide treated nets

November 24, 2008

In low-transmission areas, if widely used, artemisinin combination therapy (ACT) may reduce malaria transmission as effectively as the widespread use of insecticide-treated bed nets, says a new study published in next week's PLoS Medicine. The study also finds that the use of longer-acting anti-malarial regimens with or without artemisinin components may be an effective way to reduce transmission in high-transmission areas, provided the development of parasite resistance can be avoided. Lucy Okell and colleagues from the London School of Hygiene & Tropical Medicine present a mathematical model that predicts the impact on Plasmodium falciparum malaria transmission of the introduction of ACT and alternative first-line treatments for malaria in six regions of Tanzania with different levels of malaria transmission.

Using data from a survey of 5700 residents in Tanzania prior to the introduction of ACT, the model predicts that the relative reduction in malaria prevalence and incidence associated with a 100% switch to a short-acting ACT would be greater in areas with low initial transmission rates than in areas with high transmission rates. For example, in the area with the lowest initial transmission rates, the model predicted that the prevalence of infection would drop by 53%, but in the area with the highest initial transmission rate, the drop would be only 11%. However, because more people get malaria in high-transmission areas, the total number of malaria illness episodes prevented would be ten times higher in the area with highest transmission than in the area with lowest transmission. Using a long-acting ACT is predicted to have more effect on transmission than using a short-acting ACT, particularly in the high transmission areas. For example, the drop in the prevalence of infection in the area with highest initial transmission rates is estimated to be 36% with a long-acting ACT.

The authors say that with the renewed interest in minimizing transmission and moving toward malaria elimination, "it is increasingly important to evaluate the ability of antimalarial treatments not only to cure disease, but also to reduce transmission," as well as to maximize available resources. Their findings suggest that best public health control measures should take the properties of anti-malarial drugs into account together with the levels of transmission in the area when designing treatment policies in order to achieve the highest impact on malaria transmission.

In a related Perspective article, Maciej Boni from Oxford University and colleagues (not involved in the research) describe the importance of mathematical modeling for long-term planning of malaria control and elimination, but caution that future predictive models must take account of the potential for drug resistance. "If we can secure sustained adequate funding, and overcome all the political and operational obstacles," the authors say, "then the evolution of mosquito resistance to current insecticides and parasite resistance to current ACTs are the greatest dangers we face in our current attempts to control malaria. Mathematical modeling is an important tool for developing strategies to contain the threat of resistance."
-end-
Citation: Okell LC, Drakeley CJ, Bousema T, Whitty CJM, Ghani AC (2008) Modelling the impact of artemisinin and long-acting therapies on malaria transmission intensity. PLoS Med 5(11): e226. doi:10.1371/journal.pmed.0050226

IN YOUR COVERAGE PLEASE USE THIS URL TO PROVIDE ACCESS TO THE FREELY AVAILABLE PAPER: http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0050226

PRESS-ONLY PREVIEW OF THE ARTICLE:http://www.plos.org/press/plme-05-11-okell.pdf

READ THE EDITORS' SUMMARY OF THE PAPER: http://www.plos.org/press/plme-05-11-okell-summary.pdf

CONTACT:
Lucy Okell
London School of Hygiene and Tropical Medicine
Department of Epidemiology and Population Health
Infectious Disease Epidemiology Unit
London, London N4 1HT
United Kingdom
+44 (0)20 7927 2294
Lucy.Okell@lshtm.ac.uk

Related PLoS Medicine Perspective

Citation: Boni MF, Buckee CO, White NJ (2008)Mathematical models for a new era of malaria eradication. PLoS Med 5(11): e231. doi:10.1371/journal.pmed.0050231

IN YOUR COVERAGE PLEASE USE THIS URL TO PROVIDE ACCESS TO THE FREELY AVAILABLE PAPER: http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0050231

PRESS-ONLY PREVIEW OF THE ARTICLE:http://www.plos.org/press/plme-05-11-boni.pdf

CONTACT:
Maciej Boni
University of Oxford
Oxford University Clinical Research Unit
Hospital for Tropical Diseases
190 Ben Ham Tu
Ho Chi Minh CIty, District 5
Viet Nam
mboni@oucru.org

PLOS

Related Malaria Articles from Brightsurf:

Clocking in with malaria parasites
Discovery of a malaria parasite's internal clock could lead to new treatment strategies.

Breakthrough in malaria research
An international scientific consortium led by the cell biologists Volker Heussler from the University of Bern and Oliver Billker from the UmeƄ University in Sweden has for the first time systematically investigated the genome of the malaria parasite Plasmodium throughout its life cycle in a large-scale experiment.

Scientists close in on malaria vaccine
Scientists have taken another big step forward towards developing a vaccine that's effective against the most severe forms of malaria.

New tool in fight against malaria
Modifying a class of molecules originally developed to treat the skin disease psoriasis could lead to a new malaria drug that is effective against malaria parasites resistant to currently available drugs.

Malaria expert warns of need for malaria drug to treat severe cases in US
The US each year sees more than 1,500 cases of malaria, and currently there is limited access to an intravenously administered (IV) drug needed for the more serious cases.

Monkey malaria breakthrough offers cure for relapsing malaria
A breakthrough in monkey malaria research by two University of Otago scientists could help scientists diagnose and treat a relapsing form of human malaria.

Getting to zero malaria cases in zanzibar
New research led by the Johns Hopkins Center for Communication Programs, Ifakara Health Institute and the Zanzibar Malaria Elimination Program suggests that a better understanding of human behavior at night -- when malaria mosquitoes are biting -- could be key to preventing lingering cases.

Widely used malaria treatment to prevent malaria in pregnant women
A global team of researchers, led by a research team at the Liverpool School of Tropical Medicine (LSTM), are calling for a review of drug-based strategies used to prevent malaria infections in pregnant women, in areas where there is widespread resistance to existing antimalarial medicines.

Protection against Malaria: A matter of balance
A balanced production of pro and anti-inflammatory cytokines at two years of age protects against clinical malaria in early childhood, according to a study led by ISGlobal, an institution supported by ''la Caixa'' Foundation.

The math of malaria
A new mathematical model for malaria shows how competition between parasite strains within a human host reduces the odds of drug resistance developing in a high-transmission setting.

Read More: Malaria News and Malaria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.