Malaria
什麼是Malaria
Malaria is a complex tropical disease caused by infection with one of several types of malaria parasites, known as Plasmodia. Some of the types cause more serious illness than others. Although these parasites can be found in many different animals, four types infect humans causing mild to severe illness. They are called falciparum, vivax, ovale and malariae. A fifth type called knowlesi that is known to infect monkeys and was previously confused with the malariae type is now recognized as a serious infection in humans. The most dangerous of the strains is falciparum.
The incubation period depends on the type of parasite. For the falciparum strain, the incubation period is generally 7-14 days; for the vivax and ovale strains, 8-14 days; for the malariae strain, 7-30 days; for the knowlesi strain, 10-12 days. Because of the somewhat lengthy incubation period for all strains, many travellers do not develop clinical illness until they return to their home country. Because the early manifestation of the infection is marked by spiking fevers, it is often difficult to distinguish malaria from other infectious diseases. Where malaria is not commonly seen, physicians are not well versed in the diagnosis and treatment of this illness.
Malaria parasites are found in many tropical and subtropical areas. Malaria is no longer a problem in countries with temperate climates.
Many of the parasites have developed resistance to commonly used anti-malaria medications, especially in Southeast Asia and sub-Saharan Africa. Recently, high levels of resistance to the most effective drug combination (artemisinin-mefloquine) for treating malaria has been found along the Thai-Myanmar border.
您如何獲得Malaria？
Malaria is transmitted by the bite of an infected female mosquito. Transmission occasionally occurs through blood transfusions, organ transplants, needle sharing and from mother to the unborn child.
易感性和抵抗力
Humans are universally susceptible to malaria infection. Persons who live in malarious regions and who are infected repeatedly, develop some degree of immunity and tolerance to the clinical effects of the disease.
有哪些症狀？
It is often difficult to distinguish the initial symptoms of malaria from any other infectious disease that begins with fever. Laboratory tests are essential to identify the presence of the parasites in the blood.
Falciparum malaria can cause a varied clinical picture, but in general, the patient develops sudden onset of fever, chills, sweats, cough, diarrhoea, difficulty breathing and headaches. The severe form of the illness may include jaundice, shock, liver and kidney failure, acute inflammation of the brain, swelling of the brain, coma and death. Prompt treatment is essential, even for mild cases, since the disease may progress suddenly and rapidly to severe consequences and death.
The vivax and ovale strains usually do not cause life threatening illness. The illness is characterized by fatigue and a rising fever, followed by shaking chills, headache and nausea. The fever ends with severe sweating. After an interval of 1, 2 or 3 days, the fever cycle is repeated for a week or a month or longer. Relapses occur over a period as long as 5 years. Gradual development of immunity reduces the frequency of attacks. and a low grade life-long infection may occur without symptoms.
The knowlesi strain causes peak fevers every 24 hours. Although infection with this strain can be fatal, the outcome may also be quite variable, including self-cure or chronic illness.
預防措施
瘧疾的預防在很大程度上取決於一年中的季節，旅行者的目的地國家，該國計劃的活動以及住宿的類型。主要預防措施有兩個：（1）避免蚊子接觸；（2）服用藥物預防感染。由於藥物可能有副作用，因此重要的是平衡藥物治療和防蚊措施。在某些情況下，僅避免蚊子就足夠了。在其他情況下，將需要避免蚊子和抗瘧疾藥物。由於傳播瘧疾的蚊子通常在黃昏和黎明之間咬人，因此在這段時間內留在經過良好檢查的區域，使用驅蟲劑並穿防護服很重要。如果在未經遮擋的住所中睡覺，請使用氯菊酯浸漬的蚊帳來驅除蚊子。前往瘧疾地區旅行之前，期間和之後必須服用抗瘧疾藥物。藥物的選擇取決於瘧疾的類型和目的地國家的耐藥性。常用的抗瘧疾藥物包括Atovaquone-Proguanil，氯喹和羥氯喹，強力黴素，甲氟喹，Primaquine等。該選擇應諮詢有關瘧疾預防知識的醫生。
治療
Treatment depends on the type of malaria parasite. Prompt treatment with appropriate anti-malarial medication is essential since delays in diagnosis and treatment are associated with increased mortality, especially for the falciparum strain. Treatment has become more complicated for this strain due to the development of serious drug resistance. There are, however, effective anti-malarial medications that should be taken under the care of a physician who is knowledgeable about malaria therapy.
驗證
通常在哪裡發生？
瘧疾在世界熱帶地區最為普遍，常年傳播。在其他地區，如亞熱帶和溫帶地區，傳播可能只發生在提供最佳氣候以支援蚊子生長髮育的季節。瘧疾在撒哈拉以南非洲和新幾內亞大部分地區流行（即不斷發生）;南亞、東南亞、大洋洲、海地、中南美洲的廣大地區;以及墨西哥、多明尼加共和國、北非和中東的部分地區。
在東南亞許多國家的森林地區，特別是在農民、獵人和伐木者之間，或人類、蚊子和猴子交往的地方，都發現了這種病菌菌株。
局部傳播可能因降雨量、溫度和海拔等影響當地蚊子數量的因素而異。
