MENVSC (Geography) / Department of Geography and Geo-Information Sciences / Semi-arid regions of Africa are prone to epidemics of malaria. Epidemic malaria occurs along the
geographical margins of endemic regions, when the equilibrium between the human, parasite and
mosquito vector populations are occasionally disturbed by changes in one or more meteorological
factors and a sharp but temporary increase in disease incidence results. Monthly rainfall and
temperature data from the South African Weather Service and malaria incidence data from
Department of Health were used to determine the influence of meteorological variables on malaria
transmission in Limpopo from 1998-2014. Meteorological influences on malaria transmission
were analyzed using time series analysis techniques. Climate suitability for malaria transmission
was determined using MARA distribution model. There are three distinct modes of rainfall
variability over Limpopo which can be associated with land falling tropical cyclones, cloud bands
and intensity of the Botswana upper high. ENSO and ENSO-Modoki explains about 58% of this
variability. Malaria epidemics were identified using a standardized index, where cases greater
than two standard deviations from the mean are identified as epidemics. Significant positive
correlations between meteorological variables and monthly malaria incidence is observed at least
one month lag time, except for rainfall which shows positive correlation at three months lag time.
Malaria transmission appears to be strongly influenced by minimum temperature and relative
humidity (R = 0.52, p<0.001). A SARIMA (2, 1, 2) (1, 0, 0)12 model fitted with only malaria cases
has prediction performance of about 53%. Warm SSTs of the SWIO and Benguela Niño region
west of Angola are the dominant predictors of malaria epidemics in Limpopo in the absence of La
Niña. Warm SSTs over the equatorial Atlantic and Benguela Niño region results in the relaxation
of the St. Helena high thus shifting the rainy weather to south-east Africa. La Niña have been
linked with increased malaria cases in south-east Africa. During El Niño when rain bearing
systems have migrated east of Madagascar ridging of the St. Helena high may produce conducive
conditions for malaria transmission. Anomalously warmer and moist winters preceding the
malaria transmission season are likely to allow for high mosquito survival and the availability of
the breeding sites thus high population in the beginning of the transmission season hence
resulting in increased epidemics. / NRF
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:univen/oai:univendspace.univen.ac.za:11602/1463 |
| Date | 20 September 2019 |
| Creators | Ngwenya, Sandile Blessing |
| Contributors | Nethengwe, N. S., Chikoore, H., Bopape, M. M. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | 1 online (xvii, 132 leaves : color illustrations, color maps), Department of Geography and Geo-Information Sciences |
| Rights | University of Venda |
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