title: The potential contribution of mass treatment to the control of Plasmodium falciparum malaria.
abstract: Mass treatment as a means to reducing P. falciparum malaria transmission was used during the first global malaria eradication campaign and is increasingly being considered for current control programmes. We used a previously developed mathematical transmission model to explore both the short and long-term impact of possible mass treatment strategies in different scenarios of endemic transmission. Mass treatment is predicted to provide a longer-term benefit in areas with lower malaria transmission, with reduced transmission levels for at least 2 years after mass treatment is ended in a scenario where the baseline slide-prevalence is 5%, compared to less than one year in a scenario with baseline slide-prevalence at 50%. However, repeated annual mass treatment at 80% coverage could achieve around 25% reduction in infectious bites in moderate-to-high transmission settings if sustained. Using vector control could reduce transmission to levels at which mass treatment has a longer-term impact. In a limited number of settings (which have isolated transmission in small populations of 1000-10,000 with low-to-medium levels of baseline transmission) we find that five closely spaced rounds of mass treatment combined with vector control could make at least temporary elimination a feasible goal. We also estimate the effects of using gametocytocidal treatments such as primaquine and of restricting treatment to parasite-positive individuals. In conclusion, mass treatment needs to be repeated or combined with other interventions for long-term impact in many endemic settings. The benefits of mass treatment need to be carefully weighed against the risks of increasing drug selection pressure.
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis and Modeling, Imperial College London, London, United Kingdom. l.okell@imperial.ac.uk
authors.forename: Lucy C
authors.initials: LC
authors.lastname: Okell
authors.forename: Jamie T
authors.initials: JT
authors.lastname: Griffin
authors.forename: Immo
authors.initials: I
authors.lastname: Kleinschmidt
authors.forename: T Déirdre
authors.initials: TD
authors.lastname: Hollingsworth
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Churcher
authors.forename: Michael J
authors.initials: MJ
authors.lastname: White
authors.forename: Teun
authors.initials: T
authors.lastname: Bousema
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Drakeley
authors.forename: Azra C
authors.initials: AC
authors.lastname: Ghani
mesh_terms: D000962:Antimalarials / Q000627:therapeutic use; D006801:Humans; D057148:Insecticide-Treated Bednets; D016778:Malaria, Falciparum / Q000188:drug therapy* / Q000453:epidemiology / Q000517:prevention & control*; D011319:Primaquine / Q000627:therapeutic use
chemical_list: D000962:Antimalarials; D011319:Primaquine