A-Level Biology: Malaria – Pathogen, Transmission and Control | A-Level 生物：疟疾的病原体、传播与防控

📚 A-Level Biology: Malaria – Pathogen, Transmission and Control | A-Level 生物：疟疾的病原体、传播与防控

Malaria is one of the most devastating infectious diseases in human history, responsible for over 200 million clinical cases and approximately 600,000 deaths every year, with the greatest burden falling on children under five in sub-Saharan Africa. In the CIE A-Level Biology syllabus, malaria serves as the classic case study for understanding host-pathogen relationships, vector-borne transmission and the scientific rationale behind disease control programmes. This article provides a comprehensive yet exam-focused walkthrough of the causative organism, its life cycle, transmission dynamics, disease mechanism, and the full range of preventive and therapeutic measures.

疟疾是人类历史上最具破坏性的传染病之一，每年导致超过两亿临床病例和约六十万人死亡，其中负担最重的是撒哈拉以南非洲的五岁以下儿童。在 CIE A-Level 生物教学大纲中，疟疾是理解宿主-病原体关系、媒介传播疾病以及疾病防控项目科学原理的经典案例。本文将全面但紧扣考点地讲解致病生物体、其生命周期、传播动态、致病机制以及各类预防和治疗措施。

1. The Pathogen: Plasmodium | 病原体：疟原虫

Malaria is caused by eukaryotic, single-celled parasites of the genus Plasmodium, classified within the phylum Apicomplexa. These protozoans possess a characteristic apical complex, a group of organelles used to invade host cells. Five species infect humans: P. falciparum (most lethal), P. vivax (most common), P. ovale, P. malariae and P. knowlesi.

疟疾由顶复门原生动物门下的单细胞真核寄生虫——疟原虫属引起。这些原虫具有特征性的尖复体（apical complex），即一组用于入侵宿主细胞的细胞器。共有五种疟原虫可感染人类：恶性疟原虫（致死性最强）、间日疟原虫（最常见）、卵形疟原虫、三日疟原虫和诺氏疟原虫。

P. falciparum is particularly dangerous because it can infect red blood cells (RBCs) of all ages, leading to very high parasite densities in the blood. It also causes infected RBCs to express adhesive proteins on their surface, making them stick to blood vessel walls — a mechanism that leads to cerebral malaria. In contrast, P. vivax mainly invades young RBCs, resulting in lower parasite loads

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