Introduction of Communicable Diseases

1. Introduction of Communicable Diseases RUAN Bing Department of Infectious Diseases, First Affiliated Hospital, School of Medicine

2. Introduce myself • Professor; Doctoral advisor; Vice-Director of Infectious Diseases Department • Office: 87236585; Mobile：13858182230 • Email: ruanbing@zjwst.gov.cn M.D. & Ph.D RUAN Bing 阮 冰

3. 传染病学科简介 传染病诊治 国家重点 实验室 55年前艰难创业，近年蓬勃发展 浙江省传染病 重点实验室 卫生部传染病 重点实验室 国家重点学科 内科学 （传染病） 2007年 2006年 卫生部 病毒性传染病 重点实验室 学科整体 水平进一 步提升！ 2002年 传染病科和 传染病研究所 创建 2001年 1996年 1956年

4. 1956 1956 2006 1997

5. Conception Communicable diseases: caused by various pathogens, transmitted to others, spread in the population Infectious diseases: caused by infection

6. Why we learn? In histry, many pestilences were rampant. plague, cholera, smallpox, influenza, malaria, schistosomiasis, kala-azar

7. Why we learn? Achievements Controlled and eradicated: smallpox, poliomyelitis, plague, cholera, measles

8. Why we learn? Many diseases are still popular. — viral hepatitis, HFRS, infectious diarrhea — zoonoses (foot and mouth disease, plague, anthrax, rabies, tuberculosis)

9. Why we learn? Some “old” diseases are re-emerging — Tuberculosis — Schistosomiasis — Cholera — Syphilis — Measles

10. Why we learn? Some “new” diseases are emerging — Pathogens found in some non-infectious diseases Helicobacter pyloyi — Pathogens found in some infectious diseases hepatitis C/E, lyme disease, legionellosis — New appeared disease AIDS, SARS, human avian influenza, resistant mutants

11. Why we learn? bioterrorism — Pathogens may be used as biological weapon (anthrax, plague, smallpox, Ebola)

12. Communicable diseases Infection & immunity Epidemic process Characteristics Diagnosis Treatment Prevention

13. Section1 Infection and immunity 13

14. Conception of infection Infection：interaction between pathogen and host Infectious disease：biochemical, physiologic, metabolic and immunologic manifestation of the interaction How infection occur? — pathogenic organisms — human reactions "opportunistic infection" environmental factors

15. Infection spectrum Pathogen is eliminated or eradicated Covert infection Overt infection Carrier state Latent infection

16. (1) Pathogen is eliminated or eradicated Non-specific immunity barrier Specific immunity — active immunity — passive immunity

17. (2) Covert infection Only make the host producing specific immune response Not having histomorphological damage — no symptoms and signs — no any biochemical changes — only discovered by immunological examinations Pathogens can be eradicated or carried

18. (3) Overt infection Make the host producing specific immune response Having pathological changes Immunity can be consolidated or temporary

19. (4) Carrier state No clinical manifestation but microorganism excreted Various forms: — virus or bacteria carrier — convalescent, healthy or incubatory carrier — acute or chronic carrier

20. (5) latent infection Locates the pathogen but can not wipes it out Can latently for a long time Can occurs overt infection What is the different point between latent infection and carrier state ?

21. The role of pathogen in the infectious process Invasiveness Virulence Amount of the pathogen Variability

22. (1) Invasiveness Invade directly — Leptospira, Filariform larva of Ancylostoma Adhere, colonize and produce enterotoxin — Vibrio cholera Promote spread — Vi antigen ofSalmonella typhi

23. (2) Virulence Toxins — Exotoxin(Vibrio cholera，Corynebacterium diphtheriae, Clostridium tetani) — Endotoxin(S. typhi, Sh. dysentery) Enzymes (Entamoeba histolytica)

24. (3) Quantity of pathogens Positive relation with pathogenicity Least number differ greatly

25. (4) Variability Factors: — environmental, drug and hereditary Various forms: — pathogenicity variation — antigenic variation — drug-resistant variation

26. The role of individual immunity in the infectious process Non-specific immunity (natural immunity) —anatomic barriers, phagocytosis, humoral effects Specific immunity (acquired, adaptive, or postinfection immunity) — cell-mediated immunity, humoral immunity

27. Section2 Epidemic process & influenced factors 27

28. Essential conditions of epidemic process Sources of infection Routes of transmission Susceptibility of the population

29. (1) Sources of infection Patients — measles Persons of covert infection — poliomyelitis, epidemic cerebrospinal meningitis Pathogen carriers — typhoid fever, bacillary dysentery Infected animals — rabies, plague, leptospirosis, scrub typhus

30. (2) Routes of transmission Air transmission Water and food transmission Contagious transmission Arthropod-bone transmission (blood-sucking arthropods: mosquito, lice, flea, sandfly, mite, tick) Blood, blood products and body fluid Mother to infant (vertical transmission)

31. (3) Susceptibility of the population The ratio of susceptible persons decide the crowd susceptibility The crowd susceptibility is relation to periodicity of an epidemic The periodicity of an epidemic may be prevented by artificial active immunization

32. Influenced factors of epidemic process Natural factors — geography;climate; ecology — focus of infection — zoonosis(plague, leptospirosis, human avian influenza) Social factors — social background; economical condition; cultural level; anti-epidemic measures

33. Section3 Characteristics of communicable diseases 33

34. Basic characteristics Pathogens Infectivity Epidemiologic feature Postinfection immunity

35. (1) Pathogens Specific Be found with natural science advancements

36. (2) Infectivity As main distinction “Infective period”

37. (3) Epidemiologic feature Endemic(sporadic occurrence, epidemic, pandemic & epidemic outbreak) Seasonal(distribution in time) Regional(distribution in space) Exotic

38. (4) Postinfection immunity Specific, active, protective Can transfer to newborns through placenta Lasting time varies with the diseases “Concomitant immunity”(helminthiasis)

39. The phase in the development of clinical course Incubation period Prodromal period Period of apparent manifestation Convalescent period

40. (1) Incubation period Normal distribution(quarantine evidence) Related with: — invading quantity of pathogens — time of the toxin (bacterial food poisoning) — wound location (rabies)

41. (2) Prodromal period Non-specific — headache, fever, fatigue, anorexia, and myalgia Coexist in many infectious diseases Usually persist one to three days even miss (sudden onset)

42. (3) Period of apparent manifestation • Special symptoms and signs presented enough — rashes, jaundice, heptomegaly, splenomegaly, meningeal irritation signs • Especially in some acute diseases — measles & varicella • Abortive type — poliomyelitis, epidemic encephalitis

43. (4) Convalescent period Immunity increases to a certain level — appetite and physical strength recovered — residual pathologic & biochemical change — infectivity may persist (convalescent carrier) Relapse & recrudescence — the symptoms repeatedly and fever rise again

44. Common symptoms and signs Fever Rash (eruption) Toxemic symptoms Mononuclear phagocyte system (MPS)

45. Fever Three phases — effervescence, fastigium, defervescence Fever types — sustained — remittent — intermittent — irregular

46. Rash (eruption) Exanthem and enanthem Appearing, distribution, order, shape Four groups: (a) mocule & papule (b) petechia & ecchymosis; (c) vesicle & pustule; (d) urticaria

47. Toxemic symptoms A lot of non-specific symptoms — fever, fatigue, general malaise, anorexia, headache, myalgia, arthralgia, skeletal pain In severe patients: — disturbance of consciousness, delirium, meningeal irritation, toxic encephalopathy, respiratory and circulatory failure (septic shock)

48. Reactions of MPS Liver Spleen Lymph nodes enlarged

49. Section4 Diagnosis of communicable diseases 49

50. Clinical data Detailed history — way of an onset — symptoms, accompanied ones Careful physical examination — specific signs (rose spot, eschar, Kopliks spots)