Sốt rét là một bệnh nhiễm trùng gan và các tế bào máu đỏ gây ra bởi các ký sinh trùng đơn bào của Plasmodium chi. Sốt rét là một trong những vấn đề sức khỏe nghiêm trọng nhất đối với con người ngày nay, ảnh hưởng đến người trên toàn thế giới và gây ra 2 triệu người chết mỗi năm. | M E D I C A L MICROBIOLOGY Malaria Malaria is an infection of liver and red blood cells caused by protozoan parasites of the genus Plasmodium. Malaria is one of the most serious health problems facing humanity today affecting four hundred million people world-wide and causing 2 million deaths each year. Four species infect man P. falciparum the most common and dangerous P. malariae P ovate and P. vivax. Life cycle Malaria is spread by the bite of an infected Anopheles mosquito. Only females of the species bite humans and transmit the disease. The parasite has a complex life cycle involving sexual reproduction in the mosquito and asexual reproduction in liver parenchymal cells and erythrocytes red blood cells in humans Fig. 1. In the a Male and female gametocytes from an infected human are ingested when mosquito feeds. b Gametocytes undergo sexual reproduction in stomach to form an oocyst containing sporozoites. c Oocyst penetrates the gut wall and the sporozoites enter salivary glands. d Sporozoites infect human when mosquito next feeds. 2. In humans e Sporozoites enter the blood and infect parenchymal liver cells. f Asexual reproduction schizogony forms schizonts in which thousands of merozoites develop. g Merozoites rupture from the liver schizonts and enter erythrocytes. h Ring-form trophozoites then sporozoites and finally merozoites develop. i Merozoites rupture from the cells to invade other erythrocytes. j Some merozoites form gametocytes that infect the female mosquito at next feed and continue life cycle. In P. ovate and P. vivax infection some sporozoites remain dormant as hypnozoites in the parenchymal cells only starting the process of schizogony months or years later. Epidemiology In spite of intensive control measures malaria remains widely distributed in the tropics and subtropics of Africa Asia and Latin America Fig. . P. falciparum and P. vivax account for 95 of all malaria cases and 80 of these occur in tropical Africa. P. .
