Malaria life cycle_Visser-Berenschot_2012 : 無料・フリー素材/写真
Malaria life cycle_Visser-Berenschot_2012 / jellevisser.photography
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
|---|---|
| 説明 | Malaria life cycle:Malaria in humans is caused by five different Plasmodium species (Plasmodium falciparum, Plasmodium vivax, Plasmodiumovale, Plasmodium malariae and the zoonotic Plasmodium knowlesi), all of which share similar life cycles. Infection begins when, via a biteand blood meal, sporozoites enter the blood stream from the salivary glands of an infected female Anopheles mosquito (1) and travel to theliver where they invade hepatocytes (liver cells) (2). There they undergo asexual multiplication resulting in thousands of daughter merozoites(new parasites) released into the bloodstream (3). This process, exoerythrocytic schizogony, is asymptomatic. Some sporozoites develop into‘‘hypnozoites’’ (Plasmodium vivax and Plasmodium ovale only) which are dormant forms that may resume replication after a period ofmonths or years to cause relapses of malaria. In the bloodstream, the sporozoites invade red blood cells where they initiate a second phase ofasexual multiplication (4). This results in the production of new merozoites which invade other red blood cells (5). This stage of ‘‘erythrocyticschizogony’’ (from Greek ‘‘schizein’’—to divide), is repeated continuously and is responsible for the disease, malaria. During the infection, thegametocytes, male (microgametocytes) and female (macrogametocytes) are produced (6) which are ingested during a subsequent mosquitoblood meal. The parasites’ sexual multiplication in the female Anopheles mosquito’s stomach (midgut) is known as the sporogonic cycle. themicrogametes penetrate the macrogametes in the mosquito’s stomach cavity, generating zygotes by fusion and meiosis (7). The zygotes becomemotile and enlarged (ookinetes) and this form penetrates the midgut wall (8) of the mosquito where it develops into oocysts. The oocysts grow,burst, and release numerous sporozoites into the coelomic cavity of the mosquito (9). The sporozoites then make their way to the mosquito’ssalivary glands awaiting the mosquito to start feeding on another human host. |
| 撮影日 | 2014-12-21 22:49:35 |
| 撮影者 | jellevisser.photography |
| タグ | |
| 撮影地 |