Currently recommended tools for measuring progress of malaria control involve large, logistically and financially demanding population-based household surveys that provide national and provincial level estimates at intervals of 2 – 5 years. Sampling in planned or spontaneous aggregations of sub-groups representative of the population, the so-called Easy Access Groups (EAGs), offers the prospect of a less resource intensive method of deriving accurate estimates of control progress.
Children >4 months presenting at the EPI vaccination clinic at Chikwawa District Hospital, any accompanying older sibling(s) aged <15 years, and their parents/guardians were surveyed monthly from May 2011 to April 2012. The derived estimates of burden of disease and uptake of control interventions were compared to that of a ‘gold-standard’ household sample of a continuous Malaria Indicator Survey (rMIS) in the same population.
When adjusted for age and controlled for confounding factors, EAG coverage and impact indicator estimates were generally comparable to those from household level estimates. A significant difference in estimates of IRS coverage remained after adjusting for known confounding factors, and is being explored in more detail.
EPI surveys are a promising tool for malaria surveillance. A hybrid sampling approach with a combination of household and EAG sampling based on geospatial modelling is being explored to assess and correct for potential remaining bias of EAG estimates where needed.