【正文】 . ⑶ Fingers, utensils (contact infection): . shigellosis, influenza. 45 ⑷ Arthropods: A. Biologic: intermediate hosts, . mosquitoes in malaria, chiggers in scrub typhus. B. Mechanical: passive transfer. . flies in amebiasis 46 ⑸ Blood, body liquid transmission Such as HBV,HIV ⑹ Vertical transmission: mother to baby ⑺ Horizontal transmission: others 47 ? Susceptible person 48 二、 Factors Influencing Epidemiological Process 49 1. Natural factors: . Climatic: season, rain, humidity. . Geographic: endemicity, schistosomiasis clonorchiasis sinensis: fresh fish 2. Social factors: Social system, socialeconomic condition, cultural background 50 Characteristics of Infectious Diseases 51 1. Basic characteristics: (1) Presence of pathogens. (2) Infectivity: duration of infection, chronic carrier. (3) Epidemiological features: age, sex, season。 especially in children ? Shock ? Hemorrhage: hemolytic anemia, intravascular coagulation ? Organ failure: kidneys, liver, lung, heart, brain, necrosis of skin 78 Chronic ? Weight loss and musclewasting ? Malnutrition: especially associated with diarrhea ? Retardation of growth and intellect in children ? Anemia: iron sequestration ? Tissue destruction: e. g. lung in pneumonia or tuberculosis, liver in hepatitis B ? Postinfective syndromes: :postviral fatigue syndrome 79 Diagnosis of Infectious Diseases 80 1. Clinical manifestations (1) Mode of onset (2) Type of fever (3) Acpanying symptoms: headache, myalgia, arthalgia etc. (4) Signs: Consciousness, jaundice, skin rash, Koplik spot, eschar, subcutaneous hemorrhage, liver, spleen, lymph nodes. 81 Pathoghomonic signs ? Measles: Koplik spots ? Mumps: swelling of parotid gland ? Scrub typhus: eschar ? Leptospirosis: myalgia, calf muscle ? Typhoid: rose spots ? Cysticercosis: subcutaneous nodules ? Hepatoencephalopathy: flapping tremor ? Shigellosis: mucuspusbloody stool ? Amebic dysentery: strawberry jamlike stool ? Rabies: hydrophobia 82 2. Epidemiological Data: (1) History of contact with similar cases. (2) Occupation, living environment and life style. (3) History of vaccination. (4) History of transfusion of blood or blood products. 83 三、 Laboratory Examinations: (1) Routine examinations: blood, urine, stool. Leukocytosis, leukopenia, eosinopenia, eosinophilia. liver functions kidney functions, etc. 84 Leukocytosis: ? Infection with virus: ? epidemic hemorrhagic fever ? Japanese B encephalitis ? infectious mononucleosis ? rabies ? Infection with bacteria, etc. 85 (2) Detection and isolation of pathogens: A. Direct examination: – malaria in blood slides, cholerae in stool, diphtheria in throat swab, – Entamoeba in rectal scrape, schistosome ova in rectal snip, rickettsia in rash aspirate, fungi in skin scrapings, pneumococci in purulent sputum, leprosy bacilli in slit skin smear – By electron microscopy: viruses in stool。 ? 95% in developing country ? Maximal nation :Africa, infection rate about 10% ? for World AIDS Day 12 Emerging infectious diseases ? SARS （ SARS—CoV） ? From to ， SARS spreaded 6 continent, 32 countries， cases of 8437，death of 916 ? In china, cases of 5327， death of 349 ? SARS: most serious emerging infectious diseases in 21 century 13 Emerging infectious diseases Avian influenza H5N1 virus H1N1 VIRUS 14 Antibiotics ? Antibiotics, within the last 60 years, ? Resulted in the cure of many previously lethal infections ? Only several years , drugresistant emerged. pathogenic staphylococci were