Use of Climate Information in Malaria Stratification/Early Warning Systems/Impact Assessment for Malaria Interventions

A report on the training workshop and stakeholder meeting hosted by the Tanzania Meteorological Agency in Dar es Salaam, Tanzania October 16th-18th 2013

Climate variability and satellite : observed vegetation responses in Tanzania

Climate and vegetation growth of an area are interrelated processes; both take place on small to global scales. However, climate change and variability impacts on vegetation in most places in the world including Tanzania is of great concern since vegetation supports many socio-economic sectors, and plays a crucial role in atmospheric greenhouse gas moderation. This study aims at investigating the changes in satellite observed vegetation greenness through the use of Normalized Difference Vegetation Index (NDVI) and its relationship with the climatic factors, mainly rainfall and sea surface temperatures (SST) in Tanzania. Advanced Very High Resolution Radiometer (AVHRR)-NDVI data from 1982 to 2008 (27 years) were used in this study. These data have been proved to be useful in studying vegetation-climate relationships in various places including East Africa and Tanzania. Correlation and simple linear regression analyses were employed to reveal the nature and magnitude of the relationship as well as trends in both rainfall and NDVI data. This study found on average decreasing trends for both NDVI and rainfall for most part of the country during the study period. Despite these trends being statistically significant, they are weak ones. The coefficients of explanation obtained from the relationship between NDVI, rainfall and SST were improved (between 50% and 80%) with the use of noise filtering technique and time lagging of the datasets. This improvement is in comparison with the weak and less than 50% before filtering and lagging of the data. These results suggest that variability in rainfall or SST, especially the Niño 3.4 SST can explain only half of the variability in vegetation amidst other environmental and human factors. Rainfall variability was found to explain more of the vegetation variability in the unimodal than in the bimodal areas while Niño 3.4 SST explains more of the vegetation variability in the bimodal than in the unimodal areas. This study has improved the current understanding of the vegetation and rainfall trends together with their relationships. The study also forms a basis for future studies in climate-vegetation relationship studies

Trends of Plasmodium falciparum prevalence in two communities of Muheza district North-eastern Tanzania: correlation between parasite prevalence, malaria interventions and rainfall in the context of re-emergence of malaria after two decades of progressively declining transmission

Abstract Background Although the recent decline of malaria burden in some African countries has been attributed to a scale-up of interventions, such as bed nets (insecticide-treated bed nets, ITNs/long-lasting insecticidal nets, LLINs), the contribution of other factors to these changes has not been rigorously assessed. This study assessed the trends of Plasmodium falciparum prevalence in Magoda (1992–2017) and Mpapayu (1998–2017) villages of Muheza district, North-eastern Tanzania, in relation to changes in the levels of different interventions and rainfall patterns. Methods Individuals aged 0–19 years were recruited in cross-sectional surveys to determine the prevalence of P. falciparum infections in relation to different malaria interventions deployed, particularly bed nets and anti-malarial drugs. Trends and patterns of rainfall in Muheza for 35 years (from 1981 to 2016) were assessed to determine changes in the amount and pattern of rainfall and their possible impacts on P. falciparum prevalence besides of those ascribed to interventions. Results High prevalence (84–54%) was reported between 1992 and 2000 in Magoda, and 1998 and 2000 in Mpapayu, but it declined sharply from 2001 to 2004 (from 52.0 to 25.0%), followed by a progressive decline between 2008 and 2012 (to ≤ 7% in both villages). However, the prevalence increased significantly from 2013 to 2016 reaching ≥ 20.0% in 2016 (both villages), but declined in the two villages to ≤ 13% in 2017. Overall and age specific P. falciparum prevalence decreased in both villages over the years but with a peak prevalence shifting from children aged 5–9 years to those aged 10–19 years from 2008 onwards. Bed net coverage increased from  98% in 2001 and was ≥ 85.0% in 2004 in both villages; followed by fluctuations with coverage ranging from 35.0 to ≤ 98% between 2008 and 2017. The 12-month weighted anomaly standardized precipitation index showed a marked rainfall deficit in 1990–1996 and 1999–2010 coinciding with declining prevalence and despite relatively high bed net coverage from 2000. From 1992, the risk of infection decreased steadily up to 2013 when the lowest risk was observed (RR = 0.07; 95% CI 0.06–0.08, P < 0.001), but it was significantly higher during periods with positive rainfall anomalies (RR = 2.79; 95% CI 2.23–3.50, P < 0.001). The risk was lower among individuals not owning bed nets compared to those with nets (RR = 1.35; 95% CI 1.22–1.49, P < 0.001). Conclusions A decline in prevalence up to 2012 and resurgence thereafter was likely associated with changes in monthly rainfall, offset against changing malaria interventions. A sustained surveillance covering multiple factors needs to be undertaken and climate must be taken into consideration when relating control interventions to malaria prevalence

MOESM2 of Trends of Plasmodium falciparum prevalence in two communities of Muheza district North-eastern Tanzania: correlation between parasite prevalence, malaria interventions and rainfall in the context of re-emergence of malaria after two decades of progressively declining transmission

Additional file 2. Overall and age specific prevalence of Plasmodium falciparum detected by microscopy in the two villages of Magoda (1992–2017) and Mpapayu (1998 to 2017) in Muheza district north-eastern Tanzania

MOESM1 of Trends of Plasmodium falciparum prevalence in two communities of Muheza district North-eastern Tanzania: correlation between parasite prevalence, malaria interventions and rainfall in the context of re-emergence of malaria after two decades of progressively declining transmission

Additional file 1. Number of individuals sampled in CSS which were conducted in Magoda and Mpapayu between 1998 and 2016