Role of mass drug administration in elimination of Plasmodium falciparum malaria: a consensus modelling study

Abstract

SummaryBackgroundMass drug administration for elimination of Plasmodium falciparum malaria is recommended by WHO in some settings. We used consensus modelling to understand how to optimise the effects of mass drug administration in areas with low malaria transmission.MethodsWe collaborated with researchers doing field trials to establish a standard intervention scenario and standard transmission setting, and we input these parameters into four previously published models. We then varied the number of rounds of mass drug administration, coverage, duration, timing, importation of infection, and pre-administration transmission levels. The outcome of interest was the percentage reduction in annual mean prevalence of P falciparum parasite rate as measured by PCR in the third year after the final round of mass drug administration.FindingsThe models predicted differing magnitude of the effects of mass drug administration, but consensus answers were reached for several factors. Mass drug administration was predicted to reduce transmission over a longer timescale than accounted for by the prophylactic effect alone. Percentage reduction in transmission was predicted to be higher and last longer at lower baseline transmission levels. Reduction in transmission resulting from mass drug administration was predicted to be temporary, and in the absence of scale-up of other interventions, such as vector control, transmission would return to pre-administration levels. The proportion of the population treated in a year was a key determinant of simulated effectiveness, irrespective of whether people are treated through high coverage in a single round or new individuals are reached by implementation of several rounds. Mass drug administration was predicted to be more effective if continued over 2 years rather than 1 year, and if done at the time of year when transmission is lowest.InterpretationMass drug administration has the potential to reduce transmission for a limited time, but is not an effective replacement for existing vector control. Unless elimination is achieved, mass drug administration has to be repeated regularly for sustained effect.FundingBill & Melinda Gates Foundation.

Not all MDAs should be created equal – determinants of MDA impact and designing MDAs towards malaria elimination

“…The theoretically best timing of MDA campaigns relative to the malaria season peak have been investigated in (32). Critically, those models do not incorporate implementation logistics in a detailed manner, either simulating instantaneous MDA deployment in all villages, or having a synchronously increasing global coverage until a target coverage is reached.…”

Toward Health Management of Major Labour Force Generation by Using Infection Control Countermeasures for Haematobium Schistosomiasis –assumed to be related to occupational risk- in the Republic of Malawi

“…These results showed that MDA of praziquantel could certainly reduce egg positive prevalence of haematobium schistosomiasis. Although MDA is not an effective replacement for the existing vector control, MDA has the potential to reduce transmission for a limited time and has to be repeated regularly for sustained effect [38]. However, the egg positive prevalence in August 2013 was reduced from 3.8% to 0.9% two months after MDA (p=0.050).…”

Modelling microbial infection to address global health challenges

“…In a consortium, several modelling groups develop their models independently, each applying their particular expertise and perspective. For example, consortia of malaria modellers were convened to predict the effectiveness of interventions, including a vaccine candidate 101 and mass drug administration 102 . Congruence of output among models engenders confidence that model results are robust.…”