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Theml, Color Atlas of Hematology - part 9

Trong số các bệnh ký sinh trùng, có lẽ chỉ sốt rét phù hợp chẩn đoán thực tế ở Bắc bán cầu, trong khi tại cùng một thời gian sốt rét tham gia của hồng cầu có thể nhầm lẫn giữa việc giải thích các hình thái hồng cầu. Đối với những lý do này, một kiến thức của các hình thức khác nhau chủ yếu hình thái học của sốt rét plasmodia được khuyến khích. | 158 Erythrocyte and Thrombocyte Abnormalities Hematological Diagnosis of Malaria Various parasites may be found in the blood stream e.g. trypanosomes and filariae. Among the parasitic diseases probably only malaria is of practical diagnostic relevance in the northern hemisphere while at the same time malarial involvement of erythrocytes may confuse the interpretation of erythrocyte morphology. For these reasons a knowledge of the principal different morphological forms of malarial plasmodia is advisable. Recurrent fever and influenza-like symptoms after a stay in tropical regions suggest malaria. The diagnosis may be confirmed from normal blood smears or thick smears in the latter the erythrocytes have been hemolyzed and the pathogens exposed. Depending on the stage in the life cycle of the plasmodia a variety of morphologically completely different forms may be found in the erythrocytes sometimes even next to each other. The different types of pathogens show subtle specific differences that once the referring physician suspects malaria are best left to the specialist in tropical medicine who will determine which of the following is the causative organism Plasmodium vivax tertian malaria Plasmodiumfalciparum falciparum or malignant tertian malaria and Plasmodium malariae quartan malaria Table 27 Fig.56 . Most cases of malaria are caused by P vivax 42 and P. falciparum 43 . The key morphological characteristics in all forms of malaria can be summarized as the following basic forms The first developmental stage of the pathogen generally found in quite large erythrocytes appears as small ring-shaped bodies with a central vacuole called trophozoites or the signet-ring stage Fig. 57 . The point-like center is usually most noticeable as it is reminiscent of a Howell-Jolly body and only a very careful search for the delicate ring form will supply the diagnosis. Occasionally there are several signet-ring entities in one erythrocyte. All invaded cells may show reddish .