Based on the morphology, distribution and development of the rash, combined with the epidemiological situation, the diagnosis of typical cases is not difficult, but the diagnosis of difficult cases depends on the virus and serum immunological examination. The total number of leukocytes in the prodromal phase is slightly low, while the number of lymphocytes is relatively high, and the total number of leukocytes and neutrophils in the pustular phase are increased. 2, pathogenic examination (1) direct smear examination smallpox virus inclusion body: take herpes fluid, or herpes ulcer bottom swab coated on a slide, dried with hematoxylin-eosin (H-E) staining, under the light microscope to observe the cytoplasm of epithelial cells, if the smallpox patients, smallpox virus eosinophilic inclusion body can be found in them, but, smear negative can not exclude smallpox. (2) Electron microscopic examination: from the lesion part of the material, observed by electron microscopy, smallpox virus is brick-shaped, the diagnosis can be confirmed within a few hours. (3) chicken embryo inoculation or cell culture: take herpes fluid, scab suspension, blood or nasopharyngeal secretions, inoculated in chicken embryo chorionic vesicle membrane isolated virus, or inoculated monkey kidney cells or amniotic cells for culture, 12h can see most of the tiny inclusion body, 48h after the inclusion body significantly increased, sometimes visible in the nuclear inclusion body. 3, serological examination available complement binding test, erythrocyte agglutination inhibition test, neutralization test to detect the presence of specific antibodies in the patient’s serum to help diagnose smallpox patients as early as day 4 of the disease, the serum can appear smallpox virus antibodies. On the 7th day after the disease, the majority of patients have a positive complement binding test, and the potency can reach 1:640 on the 10th to 11th day, while the potency rarely exceeds 1:40 in non-smallpox patients with a history of the pox; however, if a suspected patient with a history of the pox has a 4-fold increase in serum antibody potency later in the course of the disease compared to the early stage, it is of diagnostic value. 4, pathological changes epidermis with reticular degeneration, ballooning degeneration or coagulative necrosis, because the reticular degeneration is more obvious, so most of the multi-room blisters, early involvement of the cytoplasm can be found in Guamieri vesicles, round or ovoid, eosinophilic and Feulgen-positive, often surrounded by uncolored transparent area, in addition, in the old lesions commonly found in the nucleus eosinophilic inclusions, dermis In addition to mild inflammatory reactions, hemorrhage is sometimes seen in the dermis.