communicable diseases in short form for mbbs students

communicable diseases in relation to NEXT exam

1. Chicken pox Case fatality rate : 3 per lakh cases In 2013;India: 28000 cases & 61 deaths Case fatality : 0.21 % Secondary attack rate: 90% Common among < 10 yrs of age Congenital varicella syndrome in 0.4 – 2% of children born to infected mothers

2. Incubation period: 7 -21 days If varicella develops within 5 days of delivery, newborn is potential to develop disseminated disease, Ig to be given Control: isolation of cases for 6 days after the onset of rash

3. Prevention: VZIG: within 72 hrs of exposure Immunosuppressed persons Should not be given together with vaccine

4. Vaccine Live attenuated monovalent vaccine Combined vaccine : MMRV Should not be given in immunocompromised persons, pregnant women Salicylates avoided for 6 weeks after vaccination Effective for 10 years Shift of disease to adult

5. Measles Occurs only in humans 2% under 5 mortality in India 2010- 2020 global measles strategic plan: achieve & maintain high levels of population immunity Establish effective surveillance Outbreak preparedness Engage public by communication Research & development

6. Challenges in measles elimination Weak immunisation systems High infectious nature Inaccessible population Refusal of immunisation by populations Changing epidemiology Need for catch up vaccinations in 130 million children Gaps in human & financial resources

7. Complications : Otitis media: 5- 15% of cases Pneumonia:20 – 80 % in developing countries most life threatening (90% of measles related deaths) Febrile convulsions Encephalitis

8. Sub acute sclerosing pan-encephalitis: 1 in 300000 Measles in pregnancy : not associated with abnormalities in foetus; associated with spon . Abortion & premature delivery

9. Rubella Enveloped RNA virus Isolated in 1962 No known carrier state Less communicable than measles Transplacental spread Usual age: 3 – 10 years 40% of reproductive age group female are susceptible Life long immunity

10. Incubation period: 2-3 weeks Furscheimers spots: petechial exanthem on soft palate Vaccine: live attenuates Strain: RA27/3 Priority groups: women of child bearing age, children 1- 14 years of age, all children at 1year CI: pregnancy; avoid pregnancy 3 months

11. Congenital rubella syndrome Most important factor: GA at the time of infection Greater damage : first trimester, 2 nd trimester: only deafness; infection after 16 weeks: no major abnormalities Triad: cataract, deafness, CHD IgM at birth at diagnostic, persistence of IgG after 6 months

12. Mumps RNA virus of paramyxoviridae Man : only natural host; Period of communicability: 4- 6 days before the onset of symptoms to a week thereafter Secondary attack rate: 86% Incubation period: 2-3 weeks (14-21 days) 30- 40 % cases are subclinical

13. Complications: orchitis is common postpubertal males, aseptic meningitis is most common complication May develop before, during or in the absence of parotitis Life long immunity

14. Mumps vaccine Live attenuated vaccine Jeryll lynn strain Others: L- Zagreb, Urabe strain. A single im dose : 95% efficacy 1 st dose- over 1 year 2 nd dose- before starting to school

15. Influenza RNA orthomyxovirus 3 types: A(all pandemics & most epidemics) Currently circulating: H1N1 (swine flu), H2N2, H3N2 & H5N1(bird flu); H7N9 (epidemic of avian influenza in China in 2013) & B cyclical trend: epidemic (2-3 yrs) & pandemic (~15 yrs)

16. Shift: sudden ; genetic recombination of human with avian virus Drift: slow; point mutation Major antigenic shifts- H2N2 (1957) & H3N2 (1968) Reservoir of infection- swine, horses, dogs, cats, domestic poultry, wild birds Source of infection- subclinical case Period of infectivity- 1 to 2 days

17. Incubation period- 18 to 72 hrs Laboratory diagnosis: virus isolation, Serology (HI & ELISA) Vaccines- 70- 90% effective Killed - 2 doses; revaccination on annual basis Live attenuated vaccine- 2 -49 years

18. Anti viral drug- Ostelamivir (75mg twice daily for 5 days); Zanamivir - 10mg inhaler twice daily Pandemic flu (swine flu); H1N1- 2009; case fatality – 23.2 Lab diagnosis- RT- PCR Infection control- hand hygiene, use of pariculate respirator (N95, FFP2 or equivalent) Duration of isolation- 7 days after onset

19. Diptheria Corynebacterium diptheriae False membrane- greyish or yellowish membrane over larynx, pharynx (or at site of implantation), cannot be wiped away

20. Shift in age distribution India - endemic disease; declining trend In 2013; 4090 cases and 64 deaths reported Source of infection- case or carrier; Carrier - common source of infection, ratio estimated is 95 carrier to 5 clinical cases Period of infectivity- 14 to 28 days Incubation period- 2 to 6 days

21. Detection of cases- active search among contacts; carriers detected by throat swab Isolation: suspected case isolated for 14 days; atleast 2 consecutive nose and throat swabs taken 24 hrs apart Treatment: Cases- diptheria antitoxin ; Penicillin or erythromycin

22. Contacts : Immunisation within 2 years- one booster dose of diptheria Non immunised contacts- prophylactic erythromycin or penicillin and 1000- 2000 units of diptheria antitoxin and active immunisation

23. DPT Vaccine: 2 types- plain adsorbed Storage- 2 to 8 degrees Optimum age- as early as 6 weeks of age Number of doses- 0.5 ml ; 3 doses Interval between doses- 4 weeks Booster- one and half year, 5 to 6 years Reactions- fever and mild local reaction; severe- encephalitis, encephalopathy, convulsions, infantile spasms, reyes syndrome

24. Pentavalent vaccine: 5 diseases- diptheria , pertussis , tetanus, hepatitis B HiB 0.5 ml anterolateral aspect of mid thigh, auto disabled syringe Freeze sensitive vaccine; storage- 2 to 8 degrees

25. Pertussis B. Pertussis Whoop- loud crowing inspiration Hundred day cough Age shift India: 2014- 61,417 cases reported

26. Source of infection- mild cases, no subclinical cases Infective period- a week after exposure to about 3 weeks after onset of paroxysmal stage No carrier state known Secondary attack rate- 90% Incubation period- 7 to 14 days

27. Clinical course Catarrhal stage- 10 days; Paroxysmal stage- 2- 4 weeks; rapid consecutive coughs followed by high pitched inspiration; cyanosis apnoea Convalescent stage- 1 to 2 weeks

28. Complications: 5-6% cases Bronchitis, bronchopneumonia, bronchiectasis ; subconjunctival hemorrhage , epistaxis , hemoptysis , punctate cerebral hemorrhages Pertussis associated encephalopathy -0.9 % cases Mortality in 3.9% in Infants; 1% in children

29. Management Cases – diagnosis, isolation, treatment & disinfection Drug of choice- erythromycin 30- 50 mg/ kg body weight in 4 divided doses for 10 days Contacts- Prophylactic antibiotic for 10 days & booster dose of vaccine

30. Vaccine efficacy for pertussis component- 70- 85% Reactions: serious reactions are rarely observed in newer vaccines. Local reactions, mild fever, irritability, persistent inconsolable screaming, seizures, hypnotic hypo responsive episodes, encephalopathy Contraindications- anaphylactic reaction, encephalopathy, family history of epilepsy CNS disorders

31. Meningococcal meningitis N. Meningitidis Case fatality rate of untreated cases – 80% African meningitis belt Meningococcal epidemic (WHO definition): >100 cases per 100000 population High: >10; moderate: 2-10; low: <2 Non epidemic zone: invasive disease India- endemic

32. N. Meningitidis - 12 serotypes Source: cases and carriers Mean duration of temporary carriers is 10 months Period of communicability- becomes uninfective within 24 hours of treatment Age : highest attack rate in infants aged 3 to 12 months Incubation period- 3 to 4 days

33. Fatal within 24 – 48 hours in 5 -10 % cases even after treatment 15- 20% permanent neurological sequele

34. Management: almost 95% survival if antibiotic started in first 2 day of illness; penicillin is drug of choice. Isolation is of limited use during epidemics Carriers: rifampicin Contacts: Antibiotics like rifampicin , ceftriaxone , ciprofloxacin or azithromycin within 72 hrs for 10 days

35. Mass chemoprophylaxis: closed & medically supervised communities; DOC: ciprofloxacin, minocycline , spiramycin and ceftriaxone Vaccine: Polysaccharide or conjugate vaccine against serogroup A, C, W135 and Y

36. Immunization to prevent acute respiratory infection Measles vaccine HIB vaccine: important cause of pneumonia and meningitis Pneumococcal pneumonia vaccine: PPV23 & PCV

37. SARS Viral disease by new strain of corona virus Symptoms: fever, malaise, chills, headache, myalgia , dizziness, cough, sore throat or running nose Some cases rapid deterioration with low oxygen saturation & acute respiratory distress requiring oxygen support Progressing over 1-2 days X ray- small patchy unilateral to bilateral, generalized, interstitial or confluent infiltration ARDS

38. Incubation period : 2 to 7 days Natural reservoir: horseshoebat Can survive upto 4 days outside human body & upto 24 hours in surface at room temperature and extended periods in cold

39. Clinical case definition A history of fever or documented fever & one or more symptoms of lower respiratory tract illness (cough, difficulty in breathing, shortness of breath) & Radiographic findings consistent of pneumonia or ARDS or autopsy findings& No alternate diagnosis for findings

40. Complications: viral pneumonia, pulmonary decompensation . ARDS in 16% Period of communicability: 10 days Treatment: Ribavarin , lopinavir , ritonavir interferon type 1, IvIg , systemic steroids Mortality rate: 14% Poor prognosis in old age, hepatitis B, high LDH secretion, DM, high neutophil count, acute kidney disease, low CD4 or Cd8