Malaria's association with climatic variables and an epidemic early warning system using historical data from Gezira State, Sudan

Abstract

Malaria is a major public health problem in Sudan. Climatic variability is the main risk factor for seasonal and secular patterns of P. falciparum malaria transmission in Gezira state. The purposes of this study is to (1) develop thresholds for action in a malaria epidemic early warning system using three traditional statistical methods including the mean number of malaria cases + 2 standard deviations (SD), percentiles over the median (medium + upper third quartile), and the cumulative sum over prior 10 years (C-SUM) and (2) explore to what extent the climate variability affects malaria transmission. Pearson's correlation coefficient for malaria incidence and rainfall, maximum temperature, relative humidity, and the Blue Nile River level was statistically significant (p < 0.05). However, there was an insignificant correlation between the number of malaria cases and the minimum temperature. Furthermore, the number of cases in 2015 was significantly higher than expected. An evaluation and comparison of the statistical methods for the early detection of malaria showed that there was a considerable variation in the number of cases exceeding an epidemic alert threshold.

Description of malaria epidemics and normal transmissions using rainfall variability in Gondar Zuria highland District, Ethiopia

“…A positive correlation between the previous month's rainfalls (one month lagged) or before the previous month's rainfall (two months lagged) and malaria case counts were reported across all the districts in Limpopo province (South Africa) [25]. A major role of rainfall compared to the minor role of temperature in malaria transmission was also indicated in stable malaria-endemic lowland areas of Sudan [23] and South Africa [26]. Heavy summer rain could also affect malaria transmission due to its killing effect of the aquatic immature mosquito stages.…”

“…In Gezira state (agricultural area in Sudan), linear positive correlations among the number of malaria cases and the relative humidity, the amount of rainfall, and the Blue Nile's level (p < 0.05) were observed compared to a non-linear relationship with the minimum temperature [23].…”

“…The rainfalls in March -June were responsible for malaria counts in the Bulg season with a peak in May/June.During the study period, the highest mean maximum temperature (31C o ) was found in March and April while the lowest temperature (11 C o ) was recorded in December and followed by January (12 C o ). Mean ± SD (range)) for monthly maximum, average and minimum temperature were 24.58 ± 2.4 (15 -31), 20.2 ± 2.3(16 -25), and 15.2 ± 2.3(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) respectively for the study period.…”

The Phylodynamic and Spread of the Invasive Asian Malaria Vectors, Anopheles stephensi, in Sudan

“…stephensi [35]. More importantly, local and international studies have reported that climate change is a major driver for the increase in the transmission of malaria and other vector-borne diseases [36,37]. As a sub-Saharan country where most of the environment throughout the country constitutes deserts and semi-deserts, the survival of diseases vectors is mainly limited to microenvironments surrounding water bodies with grassy covers such as banks of rivers [3].…”

Epidemiological Descriptive Analysis of Disease Outbreaks in 2019 in Sudan

“…The occurrence of these diseases is mostly attributed to the limited access to and coverage of clean drinking water, sanitation, and environmental protection as well as the low rate of immunization in the country [8]. Malaria remains endemic in the country, and severe outbreaks occurred as epidemics in 1990, 1993-1994, 1995, and 2003-2004 because of the high degree of malaria transmission [9].…”