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1、疟 疾 malaria,汕头大学医学院第一附属医院感染科 李涛,概 述, 疟疾是由疟原虫感染引起的寄生虫病，主要由雌性按蚊叮咬传播。广泛流行于热带、亚热带及温带地区。全世界每年约有300万人死于本病。 临床上反复发作的间歇性寒战、高热、继之以大汗后缓解为特征。,病 原 学,人疟原虫虫种 间日疟 P.v 三日疟 P.m 恶性疟 P.f 卵型疟 P.o 间日疟和卵形疟可出现复发，恶性疟发热不规则，病情较重，并可引起脑型疟。,Species Infecting Humans,Plasmodium falciparum Malignant tertian (Cerebral) Plasmodium v
2、ivax Tertian Plasmodium ovale Tertian Plasmodium malariae Quartan,Common & SevereRare & Mild,Species Infecting Humans,Plasmodium falciparum Tropical Africa, Asia, Latin America Plasmodium vivax Worldwide Plasmodium ovale Tropical West Africa Plasmodium malariae Worldwide but very patchy,Relapses Fev
3、ers No 24-48Yes 48Yes 48No 72,Morphology and Life Cycle,Two hosts are required in the life cycle of human Plasmodia: human and mosquitoes,Human is the intermediate host, the asexual reproduction occur in liver and RBCs of the human host;,Mosquito is the final host, the sexual reproduction takes plac
4、e in the stomach of mosquito.,Life cycle and Morphology,Asexual reproduction in man,Development in RBCs (erythrocytic stage),Development in liver (exo-erythrocytic stage),Sexual and asexual reproduction in mosquito,Development in human body,The infective form is the sporozoite (子孢子）,a small, spindle
5、-shaped cell with a single nucleus, which developed in mosquito, and is introduced into man by the bite of an infected mosquito.,exo-erythrocytic stage(红外期),The sporozoites was injected into human body with the saliva,The sporozoite quickly leaves the blood stream and enters a parenchyma cell of the
6、 liver where it undergoes a cycle of growth and reproduction by schizogony.,Schizont 裂殖体,schizont mature in 6-14 days, the liberation merozoites enter the blood stream.,exo-erythrocytic schizont in liver.,The schizonts become mature,The schizonts contain thousands of merozoites,The infected liver pa
7、renchyma cell is broken,merozoites,Some of merozoites are eaten by macrophages,Some of merozoites pene-trate into the red blood cells to start their developmentin RBC,The sporozoites that establish in the liver cells are proved of two genetic forms,Tachysporozoite (速发型子孢子).,Those developing into tro
8、phozoites and undergoes EE schizogony immediately after they enter the liver,Bradysporozoite (迟发型子孢子) or Hypnozoites.,They will remain in the liver without further development in a latent period,Bradysporozoite (迟发型子孢子),They may be activated under certain conditions and begin to develop, and multipl
9、y in the way that tachysporozoite did.,The latent period of hypnozoite is more than 3 months to 2 years when the primary attack have subsided.,The reentrance of the merozoites derived from the hypnozoites into the circulation therefore cause a secondary attack. This is considered to be mechanism of
10、relapse(复发).,在人体内的发育:红细胞外期,Erythrocytic stage(红内期),The merozoites release from the liver cells and penetrate red cells , undergo repeated cycles of growth and reproduction by schizogony.,The ring form (环状体）,merozoites,The ring form (the early stage (Trophozoite),RBC,Nucleus,The delicate blue stained
11、 ring of cytoplasm,vacuole,Malaria - Merozoite,Malaria Red blood cell invasion,Malaria Red blood cell invasion,P.vivax thin smear, showing early trophozoites. The infected red cells are enlarged and show some stippling.,early trophozoites of Plasmodium,The entire organism looks like a ruby-ring, whi
12、ch is about 1/3 that diameter of the infected RBC. (In P. vivax),The ring form (环状体）,The ring forms of P. falciparum are about 1/5 that diameter of the infected RBC; some appear to have two nuclei,P. vivax,P. falciparum,疟原虫环状体 或裂殖子,环状体Annular body,The trophozoite (滋养体）,The ring form,Trophozoite,8-10
13、 hours development in RBC, cytoplasm with the nucleus begin to enlarge while the ring forms become irregular in shape, some times projects pseudopodia, exhibits activities,Malarial pigment,Nucleus,Cytoplasm (pseudopodia),Hemozoin,The granules of dark malarial pigment, the metabolite of Plasmodium in
14、 digestion of hemoglobin now appears.,The infected RBC might show somewhat enlarged and the orange-pink spots known as Schuffners dots will appear on the surface of the infected RBC.,In Plasmodium falcipanum, The ring form trophozoites grow more than 10 hours in peripheral blood, gradually hide in t
15、he internal organ, and develop into trophozoites.,P.vivax thin smear. Showing late trophozoites (amoeboid stage).,Schizont (裂殖体）,The late trophozoite,Erythrocytic Schizont,The trophozoite becomes oval or round body, and its nucleus begins to segment. the infected RBC enlarges up to two times of the
16、normal size, and becomes pale in colour,The number of the nucleus in the mature schizont is 1224, usually 16. When it matures, its cytoplasm segments to surround every nucleus of it, and the malarial pigment becomes compact,The compact malarial pigments,P. vivax thin smear. Merozoites lying free. Malarial pigment is seen as a clump on one side.,
