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. 2014 Nov 18;9(11):e106359.
doi: 10.1371/journal.pone.0106359. eCollection 2014.

Time series analysis of trends in malaria cases and deaths at hospitals and the effect of antimalarial interventions, 2001-2011, Ethiopia

Maru Aregawi  1 , Michael Lynch  1 , Worku Bekele  2 , Henok Kebede  2 , Daddi Jima  3 , Hiwot Solomon Taffese  3 , Meseret Aseffa Yenehun  3 , Abraham Lilay  3 , Ryan Williams  1 , Madeleine Thomson  4 , Fatoumata Nafo-Traore  2 , Kesetebirhan Admasu  3 , Tedros Adhanom Gebreyesus  3 , Marc Coosemans  5
Affiliations

Time series analysis of trends in malaria cases and deaths at hospitals and the effect of antimalarial interventions, 2001-2011, Ethiopia

Maru Aregawi et al. PLoS One. .

Abstract

Background: The Government of Ethiopia and its partners have deployed artemisinin-based combination therapies (ACT) since 2004 and long-lasting insecticidal nets (LLINs) since 2005. Malaria interventions and trends in malaria cases and deaths were assessed at hospitals in malaria transmission areas during 2001-2011.

Methods: Regional LLINs distribution records were used to estimate the proportion of the population-at-risk protected by LLINs. Hospital records were reviewed to estimate ACT availability. Time-series analysis was applied to data from 41 hospitals in malaria risk areas to assess trends of malaria cases and deaths during pre-intervention (2001-2005) and post-interventions (2006-2011) periods.

Findings: The proportion of the population-at-risk potentially protected by LLINs increased to 51% in 2011. The proportion of facilities with ACTs in stock exceeded 87% during 2006-2011. Among all ages, confirmed malaria cases in 2011 declined by 66% (95% confidence interval [CI], 44-79%) and SPR by 37% (CI, 20%-51%) compared to the level predicted by pre-intervention trends. In children under 5 years of age, malaria admissions and deaths fell by 81% (CI, 47%-94%) and 73% (CI, 48%-86%) respectively. Optimal breakpoint of the trendlines occurred between January and June 2006, consistent with the timing of malaria interventions. Over the same period, non-malaria cases and deaths either increased or remained unchanged, the number of malaria diagnostic tests performed reflected the decline in malaria cases, and rainfall remained at levels supportive of malaria transmission.

Conclusions: Malaria cases and deaths in Ethiopian hospitals decreased substantially during 2006-2011 in conjunction with scale-up of malaria interventions. The decrease could not be accounted for by changes in hospital visits, malaria diagnostic testing or rainfall. However, given the history of variable malaria transmission in Ethiopia, more data would be required to exclude the possibility that the decrease is due to other factors.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Administrative regions and areas below and above 2000 meters elevation in Ethiopia.
Figure 2
Figure 2. Timeline of implementation of antimalarial interventions, 2001–2011, Ethiopia.
Figure 3
Figure 3. Percentage of population potentially protected with LLINs*, IRS and percentage of health facilities with stock of ACT available by year, 2001–2011, Ethiopia (*number of LLINs distributed during the 3 year period ×1.8/population).
Figure 4
Figure 4. Trends of confirmed malaria cases and non-malaria outpatient visits (a); slide positivity rate and number of microscopic slides examined (b); malaria admissions and non-malaria admissions (c); malaria deaths and non-malaria deaths in all ages (d) in 41 hospitals, Ethiopia 2001–2011.
Figure 5
Figure 5. Time series of monthly confirmed malaria cases, slide positivity rate, admissions and deaths extracted by use of a Hodrick-Prescott filter with monthly smoothing parameter λ = 14,400 (HP  =  Hodrick-Prescott filter; MAl-IPDAll Ages  =  Inpatient malaria cases in all ages; Mal-DeathsAll Ages  =  Malaria deaths in all ages, SPRAll Ages  =  Slide positivity rate in all ages; PositiveAll ages  =  Number of confirmed cases).
Figure 6
Figure 6. Monthly mean number of malaria confirmed cases, malaria inpatient cases, malaria deaths and slide positivity rate, 2001–2005 and 2006–2011, 41 hospitals, Ethiopia.
Figure 7
Figure 7. Trends of annually averaged rainfall (mm) in the major regions, 2001–2011, Ethiopia.
See this image and copyright information in PMC

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