Effectiveness of malaria control during changing climate conditions in Eritrea, 1998-2003.
OBJECTIVE
To assess the effectiveness of impregnated mosquito nets, indoor residual spraying and larval control relative to the impacts of climate variability in the decline of malaria cases in Eritrea.


METHODS
Monthly data on clinical malaria cases by subzoba (district) in three zobas (zones) of Eritrea for 1998-2003 were used in Poisson regression models to determine whether there is statistical evidence for reduction in cases by DDT, malathion, impregnated nets and larval control used over the period, while analysing the effects of satellite-derived climate variables in the same geographic areas.


RESULTS
Both indoor residual spraying (with DDT or malathion) and impregnated nets were independently and significantly negatively associated with reduction in malaria cases, as was larval control in one zoba. Malaria cases were significantly positively related to differences in current and previous months' vegetation (NDVI) anomalies. The relationship to rainfall differences 2 and 3 months previously was also significant, but the direction of the effect varied by zoba. Standardized regression coefficients indicated a greater effect of climate in the zoba with less intense malaria transmission.


CONCLUSIONS
The results support the view that both indoor residual spraying and impregnated nets have been independently effective against malaria, and that larval control was also effective in one area. Thus climate, while significant, is not the only explanation for the recent decline in malaria cases in Eritrea. If appropriate statistical approaches are used, routine surveillance data from cases attending health facilities can be useful for assessing control programme success and providing estimates of the effectiveness of individual control measures. Effectiveness estimates suitable for use in cost-effectiveness analysis have been obtained.
Graves
Patricia M
PM
EpiVec Consulting, Atlanta, GA, USA. pgraves@cdc.gov
Osgood
Daniel E
DE
Thomson
Madeleine C
MC
Sereke
Kiros
K
Araia
Afwerki
A
Zerom
Mehari
M
Ceccato
Pietro
P
Bell
Michael
M
Del Corral
John
J
Ghebreselassie
Shashu
S
Brantly
Eugene P
EP
Ghebremeskel
Tewolde
T
D000293:Adolescent; D000818:Animals; D001512:Bedding and Linens; D002648:Child; D002675:Child, Preschool; D002980:Climate; D003634:DDT / Q000008:administration & dosage; D019017:Eritrea / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007306:Insecticides / Q000008:administration & dosage; D008288:Malaria / Q000453:epidemiology*; D008294:Malathion / Q000008:administration & dosage; D009032:Mosquito Control / Q000379:methods*; D009313:National Health Programs; D017063:Outcome Assessment, Health Care; D016012:Poisson Distribution; D011891:Rain; D012621:Seasons
D007306:Insecticides; D003634:DDT; D008294:Malathion