Another Approach to Detect Malaria Epidemics and to Evaluate the Impact of their Control Measures in Situation of Lack of Information

Abstract

The purpose of this study is to establish a theoretical epidemiologic threshold for the rate of
reported malaria cases in order to detect epidemics and evaluate the impact of control measures.
To create this epidemiologic threshold it has been used an multiple cross-over time series
autoregressive integrated moving average forecasting model that reflects the dependence of the
magnitude of the rate of malaria reports on the past levels of rain, temperature and vegetation
density according to factors related with malaria transmission described by the MacDonald’s
theory. Information available for the model derivation and accuracy testing was obtained
from Médecins Sans Frontières in Karuzi, a Burundi’s province, with a health network of a
100-bed hospital and 11 health centers, that consists in the monthly malaria incidence rate
estimated from clinical diagnostics in medical consultations with a 5-20% of clinical cases
with microbiological confirmation in non-epidemic periods and less than 2% during outbreaks,
the cumulative monthly level of precipitation and the minimum and maximum mean monthly
temperature recorded by the local meteorological stations, as well as the NDVI provided by the
National Oceanographic and Atmospheric Administration satellites. This available information
covers the 1997-2003 period. The obtained model makes it possible to create a curve of expected
non-epidemic case reports with a reliability of 95%. This model identified four epidemics in the
7-year study period and detected the impact of a malaria control campaign in the last year. The
application of this methodological tool permits the timely detection of malaria epidemics and
the evaluation of the impact of measures for its control.