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Indigenous knowledge in seasonal rainfall prediction in Tanzania : a case of the South-western Highland of Tanzania

2010-01-01T00:00:00Z

Title: Indigenous knowledge in seasonal rainfall prediction in Tanzania : a case of the South-western Highland of Tanzania Authors: Chang’a, Ladislaus B.; Yanda, Pius Z.; Ngana, James Abstract: This paper describes how farmers in the South-western Highland of Tanzania predict rainfall using local environmental indicators and astronomical factors. The perceptions of the local communities on conventional weather and climate forecasts were also assessed. The study was conducted in Rungwe and Kilolo districts in Mbeya and Iringa regions respectively. Participatory rural appraisal methods, key informant interviews and focus group discussions were used in data collection and the collected data was analyzed using Statistical package for social science. It has been found that plant phenology is widely used by local communities in both districts in seasonal rainfall forecasting. Early and significant flowering of Mihemi (Erythrina abyssinica) and Mikwe (Brachystegia speciformis) trees from July to November has been identified to be one of the signals of good rainfall season. The behaviour of Dudumizi bird has been singled out as one of the best indicator for rainfall. Both Indigenous Knowledge specialists and TMA experts have predicted 2009/2010 rainfall season to feature normal to above normal rainfall. Systematic documentation and subsequent integration of indigenous knowledge into conventional weather forecasting system is recommended as one of the strategy that could help to improve the accuracy of seasonal rainfall forecasts under a changing climate.

Identification of malaria transmission and epidemic hotspots in the western Kenya highlands : its application to malaria epidemic prediction

2011-01-01T00:00:00Z

Title: Identification of malaria transmission and epidemic hotspots in the western Kenya highlands : its application to malaria epidemic prediction Authors: Wanjala, Christine L.; Waitumbi, John; Zhou, Guofa; Githeko, Andrew K. Abstract: Background: Malaria in the western Kenya highlands is characterized by unstable and high transmission variability which results in epidemics during periods of suitable climatic conditions. The sensitivity of a site to malaria epidemics depends on the level of immunity of the human population. This study examined how terrain in the highlands affects exposure and sensitivity of a site to malaria. Methods: The study was conducted in five sites in the western Kenya highlands, two U-shaped valleys (Iguhu, Emutete), two V-shaped valleys (Marani, Fort-Ternan) and one plateau (Shikondi) for 16 months among 6-15 years old children. Exposure to malaria was tested using circum-sporozoite protein (CSP) and merozoite surface protein (MSP) immunochromatographic antibody tests; malaria infections were tested by microscopic examination of thick and thin smears, the children’s homes were georeferenced using a global positioning system. Paired t-test was used to compare the mean prevalence rates of the sites, K-function was use to determine if the clustering of malaria infections was significant. Results and Discussion: The mean antibody prevalence was 22.6% in Iguhu, 24% in Emutete, 11.5% in Shikondi, 8.3% in Fort-Ternan and 9.3% in Marani. The mean malaria infection prevalence was 23.3% in Iguhu, 21.9% in Emutete, 4.7% in Shikondi, 2.9% in Fort-Ternan and 2.4% in Marani. There was a significant difference in the antibodies and malaria infection prevalence between the two valley systems, and between the two valley systems and the plateau (P < 0.05). There was no significant difference in the antibodies and malaria infection prevalence in the two U-shaped valleys (Iguhu and Emutete) and in the V-shaped valleys (Marani and Fort Ternan) (P > 0.05). There was 8.5- fold and a 2-fold greater parasite and antibody prevalence respectively, in the U-shaped compared to the V-shaped valleys. The plateau antibody and parasite prevalence was similar to that of the V-shaped valleys. There was clustering of malaria antibodies and infections around flat areas in the U-shaped valleys, the infections were randomly distributed in the V-shaped valleys and less clustered at the plateau. Conclusion: This study showed that the V-shaped ecosystems have very low malaria prevalence and few individuals with an immune response to two major malaria antigens and they can be considered as epidemic hotspots. These populations are at higher risk of severe forms of malaria during hyper-transmission seasons. The plateau ecosystem has a similar infection and immune response to the V-shaped ecosystems. The U-shaped ecosystems are transmission hotspots.

Surveillance of vector populations and malaria transmission during the 2009/10 El Niño event in the Western Kenya highlands : opportunities for early detection of malaria hyper-transmission

2011-01-01T00:00:00Z

Title: Surveillance of vector populations and malaria transmission during the 2009/10 El Niño event in the Western Kenya highlands : opportunities for early detection of malaria hyper-transmission Authors: Ototo, Ednah N.; Githeko, Andrew K.; Wanjala, Christine L.; Scott, Thomas W. Abstract: Background: Vector control in the highlands of western Kenya has resulted in a significant reduction of malaria transmission and a change in the vectorial system. Climate variability as a result of events such as El Niño increases the highlands suitability for malaria transmission. Surveillance and monitoring is an important component of early transmission risk identification and management. However, below certain disease transmission thresholds, traditional tools for surveillance such as entomological inoculation rates may become insensitive. A rapid diagnostic kit comprising Plasmodium falciparum circumsporozoite surface protein and merozoite surface protein antibodies in humans was tested for early detection of transmission surges in the western Kenya highlands during an El Niño event (October 2009-February 2010). Methods: Indoor resting female adult malaria vectors were collected in western Kenya highlands in four selected villages categorized into two valley systems, the U-shaped (Iguhu and Emutete) and the V-shaped valleys (Marani and Fort Ternan) for eight months. Members of the Anopheles gambiae complex were identified by PCR. Blood samples were collected from children 6-15 years old and exposure to malaria was tested using a circum-sporozoite protein and merozoite surface protein immunchromatographic rapid diagnostic test kit. Sporozoite ELISA was conducted to detect circum-sporozoite protein, later used for estimation of entomological inoculation rates. Results: Among the four villages studied, an upsurge in antibody levels was first observed in October 2009. Plasmodium falciparum sporozoites were then first observed in December 2009 at Iguhu village and February 2010 at Emutete. Despite the upsurge in Marani and Fort Ternan no sporozoites were detected throughout the eight month study period. The antibody-based assay had much earlier transmission detection ability than the sporozoitebased assay. The proportion of An. arabiensis among An. gambiae s.l. ranged from 2.9-66.7% indicating a rearrangement of the sibling species of the An. gambiae s.l complex. This is possibly an adaptation to insecticide interventions and climate change. Conclusion: The changing malaria transmission rates in the western Kenya highlands will lead to more unstable transmission, decreased immunity and a high vulnerability to epidemics unless surveillance tools are improved and effective vector control is sustained.

Assessing the impact of topography on malaria exposure and sensitivity in Western Kenya Highlands

2009-01-01T00:00:00Z

Title: Assessing the impact of topography on malaria exposure and sensitivity in Western Kenya Highlands Authors: Wanjala, Christine L. Description: Meeting: Multilateral Initiative on Malaria International Conference, 2-6 November 2009, Nairobi, KE,

Climate change challenge : implications for development in Southern and Eastern Africa

2008-01-01T00:00:00Z

Title: Climate change challenge : implications for development in Southern and Eastern Africa Authors: Odingo, Richard Description: Meeting: ESARO Seminar on Climate Change, 6 June 2008, Nairobi, KE; http://www.idrc.ca/en/ev-127079-201-1-DO_TOPIC.html