Himeidan Yousif E, Kweka Eliningaya J
Entomology Unit, Faculty of Agriculture and Natural Resources, University of Kassala New Halfa, Sudan.
Front Physiol. 2012 Aug 2;3:315. doi: 10.3389/fphys.2012.00315. eCollection 2012.
East African highlands are one of the most populated regions in Africa. The population densities in the highlands ranged between 158 persons/km(2) in Ethiopia and 410 persons/km(2) in Rwanda. According to the United Nations Population Fund, the region has the world's highest population growth rate. These factors are likely behind the high rates of poverty among the populations. As there were no employment opportunities other than agricultural, this demographic pressure of poor populations have included in an extensive unprecedented land use and land cover changes such as modification of bushland, woodland, and grassland on hillsides to farmland and transformation of papyrus swamps in valley bottoms to dairy pastures and cropland and changing of fallows on hillsides from short or seasonal to longer or perennial. Areas harvested for food crops were therefore increased by more than 100% in most of the highlands. The lost of forest areas, mainly due to subsistence agriculture, between 1990 and 2010 ranged between 8000 ha in Rwanda and 2,838,000 ha in Ethiopia. These unmitigated environmental changes in the highlands led to rise temperature and optimizing the spread and survival of malaria vectors and development of malaria parasites. Malaria in highlands was initially governed by low ambient temperature, trend of malaria transmission was therefore increased and several epidemics were observed in late 1980s and early 2000s. Although, malaria is decreasing through intensified interventions since mid 2000s onwards, these environmental changes might expose population in the highlands of east Africa to an increase risk of malaria and its epidemic particularly if the current interventions are not sustained.
东非高地是非洲人口最密集的地区之一。高地的人口密度在埃塞俄比亚为每平方公里158人，在卢旺达为每平方公里410人。根据联合国人口基金的数据，该地区是世界上人口增长率最高的地区。这些因素可能是当地人口贫困率高的原因。由于除了农业之外没有其他就业机会，贫困人口的这种人口压力导致了前所未有的广泛土地利用和土地覆盖变化，比如将山坡上的灌木丛、林地和草地改造成农田，将谷底的纸莎草沼泽改造成奶牛牧场和农田，以及将山坡上的休耕期从短期或季节性改为长期或多年生。因此，大多数高地的粮食作物收获面积增加了100%以上。1990年至2010年期间，主要由于自给农业导致的森林面积损失在卢旺达为8000公顷，在埃塞俄比亚为283.8万公顷。高地这些未得到缓解的环境变化导致气温上升，有利于疟蚊的传播和存活以及疟原虫的发育。高地疟疾最初受环境温度较低的控制，因此疟疾传播趋势增加，在20世纪80年代末和21世纪初出现了几次疫情。尽管自21世纪中叶以来通过强化干预疟疾发病率在下降，但这些环境变化可能使东非高地的人口面临疟疾及其流行风险增加的情况，特别是如果当前的干预措施不能持续下去的话。
