Seasonality of confirmed malaria cases from 2008 to 2017 in Togo: a time series analysis by health district and target group

Abstract

Background This study aimed to assess the seasonality of confirmed malaria cases in Togo and to provide new indicators of malaria seasonality to the National Malaria Control Programme (NMCP). Methods Aggregated data of confirmed malaria cases were collected monthly from 2008 to 2017 by the Togo’s NMCP and stratified by health district and according to three target groups: children < 5 years old, children ≥ 5 years old and adults, and pregnant women. Time series analysis was carried out for each target group and health district. Seasonal decomposition was used to assess the seasonality of confirmed malaria cases. Maximum and minimum seasonal indices, their corresponding months, and the ratio of maximum/minimum seasonal indices reflecting the importance of malaria transmission, were provided by health district and target group. Results From 2008 to 2017, 7,951,757 malaria cases were reported in Togo. Children < 5 years old, children ≥ 5 years old and adults, and pregnant women represented 37.1%, 57.7% and 5.2% of the confirmed malaria cases, respectively. The maximum seasonal indices were observed during or shortly after a rainy season and the minimum seasonal indices during the dry season between January and April in particular. In children < 5 years old, the ratio of maximum/minimum seasonal indices was higher in the north, suggesting a higher seasonal malaria transmission, than in the south of Togo. This is also observed in the other two groups but to a lesser extent. Conclusions This study contributes to a better understanding of malaria seasonality in Togo. The indicators of malaria seasonality could allow for more accurate forecasting in malaria interventions and supply planning throughout the year.

Exploring malaria prediction models in Togo: a time series forecasting by health district and target group

“…The time series of confirmed malaria cases showed the presence of an artificial peak in September 2016, as described elsewhere 3. A spline interpolation imputation was performed to replace the values of this peak.…”

“…The time series of confirmed malaria cases showed the presence of an artificial peak in September 2016, as described elsewhere. 3 A spline interpolation imputation was performed to replace the values of this peak. Two health districts (Kpendjal and Oti) had no monthly confirmed malaria cases reported in 2016, but the total number of cases for that year was not used for analysis.…”

“…Seasonal and geographical variations of malaria have been identified in Togo, with an increase in confirmed malaria cases during or shortly after a rainy season and greater seasonal variations of malaria in the northern health districts, particularly in children <5 years old 3. Several studies in sub-Saharan Africa showed the association between meteorological and environmental factors and malaria cases 4–10.…”

“…2 Seasonal and geographical variations of malaria have been identified in Togo, with an increase in confirmed malaria cases during or shortly after a rainy season and greater seasonal variations of malaria in the northern health districts, particularly in children <5 years old. 3 Several studies in sub-Saharan Africa showed the association between meteorological and environmental factors and malaria cases. [4][5][6][7][8][9][10] A systematic review published by Reiner et al showed that temperature and rainfall were often found to be significant predictors of malaria seasonality, along with vegetation indices such as the normalised difference vegetation index (NDVI).…”

Climate Change-Related Disaster Risk Events in Togo: A Systematic Review

“…The seasonality of malaria cases in Togo increases during or after the rainy season and is more intense in the northern health districts, especially in children under 5 years old (Expédit Evariste et al, 2005;Agbossou et al, 2022). Factors like rainfall, temperature, and topography should be considered in malaria control activities when analysing malaria seasonality (Thomas et al, 2021). Potential adaptation strategies include improving water-related issues, such as sanitation and hygiene standards, and implementing mosquito control measures.…”