PSM Quick Revision Notes (PDF)

PSM / COMMUNITY MEDICINE QUICK REVISION NOTES Strength of Association in a Cohort Study Q...

PSM / COMMUNITY MEDICINE QUICK REVISION NOTES Strength of Association in a Cohort Study Q Relative Risk (Risk Ratio) (RR) - Ie/Ine Clinician Ie - Incidence in Exposed UNIT 1 Ine - Incidence in Non-exposed EPIDEMIOLOGY It - Incidence in Total Study of diseases among people 3 parts; Distribution, Determinates, Frequency RR > 1 - Association + Distribution - Time, Place, Person RR = 1 - No Association Determinates - Causative agent RR < 1 - Negative/Inverse Association Q Frequency - How the disease is increasing Attributable Risk (AR) - Ie-Ine/ Ie x 100 or decreasing among the population through incidence & prevalence “Epidemiologist” Definition was first presented by Sir John M. Synonyms of AR Last Absolute Risk Compromises of finding the causative agent or determinant of a disease by formulating a Excess Risk hypothesis with Risk Difference 1) Descriptive Epidemiology 2) Analytical Epidemiology Population Attributable Risk (PAR) - It-Ine/ It x 100 3) Experimental/ Interventional Epidemiology “PH Prog. Manager” Types of Study Major Problem - Time, Money, Ethical, Hawthorne 1) COHORT STUDY- Forward/ Prospective/ Cause- Bias Effect/Exposure to Outcome/Risk Factor to Disease/ Advantage - More accurate Incidence/ Follow-up StudyQ 2) CASE CONTROL STUDY- Backward/ Retrospective/ Effect-Cause/Disease to Risk/ Outcome to Exposure/ Case Reference StudyQ TROHOC Study Fig 1: Cohort Study design 2 Cerebellum Quick Revision Notes ODDS Ratio - ad/bc OR > 1, Association +Q OR = 1, No Association OR 99%, AMMRS( Diluent used - Normal SalineQ Accelerated Measles Mortality Reduction Used within 21 yrs - 2 doses Immunocompromised - 3 doses COLD CHAIN of Vaccine Maintenance of temp of vaccine from manufacture to administrationQ Fig 20: Dial Thermometer –– All vaccines - +2°↔+8°C Based on the principle of Thermocouple –– Exception OPV required for long term storage Temperature is monitored twice a day. = -15°C to 25°C, YF = -30°↔+5°C Alcohol stem thermometer is more sensitive Instrument - but Dial thermometer is more easy to use. 1. ILR(Ice Lined Refrigerator)Q Fig 19: ILR 16 Cerebellum Quick Revision Notes Fig 21: ILR 2. Vaccine Carrier Uses four fully frozen ice packs on each side, 16-20 vaccine vials, upto 24-48hrsQ Fig 23: Ice pack Open Vial PolicyQ If vaccine is maintained well under required temp while administration, transporting and such it can Fig 22: Vaccine Carrier used upto 28 days 3. Ice Pack Applicable - OPV, DPT, DT, Td, TT, Hep B, Pentavalent Vaccine, iPV, PCV Smallest component for cold chain.Q Not Applicable - BCG, M/MR/MMR, JE. RVV, Covid-19 2 vaccines are kept in two holes inside the ice vaccine pack. Horozontal marks indicates water filling level.  17 PSM / Community Medicine AEFI (Adverse effects following Immunization) 30 mins observation after child is vaccinated –– Paralysis - OPV –– HS/Anaphylaxis/Shock - Hep B –– Persistent crying - PertussisQ –– HHE - Pertussis A. Disease Onset –– TSS - MeaslesQ –– Intesusception - RVVQ B. First Possible Detection –– GBS - Killed Influenza vaccineQ C. Critical Point –– Thrombocytopenia - MMR & Hep B D. Visual Time of Diagnosis Contraindications to vaccination E. Final Outcome of The Disease Pregnancy - All Live vaccine except YF Point A & B : Screening test is not possible Lactation - YF is C/I Point C & D : Critical point is already passed HIV+ - All Live vaccine C/I so no benefit Epilepsy - Pertussis C/IQ If screening test is applied it should be btw C.palsy - No C/IQ point B & C to be effective Epidemics - All vaccines C/I except measles There is a possibility to alter the final outcome of the disease to F Post Disaster - All vaccines C/I except measles Lead TimeQ UNIT 4 Without using screening tests , when will the disease be diagnosed later and by using screening test , how much earlier a disease can be detected in early stages , i.e Leading the time for detection of diseases - It is an Advantage gained by screening. A. Screening Test for Cervical Cancer 1. VIA (Visual Inspection with 5% Acetic Acid) (Cost-effective) 2. Pap Smear 3. VILI (Visual Inspection with Lugol’s Iodine) Positive then Dx. confirmed by Colposcopic Screening of Disease Punch Biopsy (Diagnosis) Early/Rapid detection of disease in apparently healthy individuals by using –– Rapidly Applied Tests 18 Cerebellum Quick Revision Notes B. Screening Test for Breast Cancer 1. Mammography best test but, not used in females aged < 40 years (Due to high breast tissue density)Q 2. Ideal test in young females - MRI Fig 3. Mammography 3. Ultrasonography C. Screening Test for Diabetes Mellitus I. RBS 4. Thermography 3. Diagnostic tests: 5. Palpitation by physician 1. FBS - > 126 mmd/dL 2. HbA1C - > 6.5 6. BSE (Breast Self Examination) 3. OGTT (Oral Glucose Tolerance Test)- > 200 mg/dL (75g Oral glucose given)(Venous Plasma Glucose level at 2 hrs) Fig 4: OGTT  19 PSM / Community Medicine D. Screening Test for Tuberculosis –– Positive out of Disease - Sens I. Clinical History (Cough > 2 wks) –– Disease out of Positive - PPV Diagnostic test: –– Positive+Diseased – TP 1. Sputum Smear Examination (ZN Stain) - 3. PPV (Positive Predictive Value) - Diagnostic Limitation - Minimum bacillary load of 10,000 PowerQ bacilli/ml sputum PPV = a/(a+b) x 100 = TP/(TP+FP) x 100 2. LED-FM Microscopy TP - True Postive 3. Automated Liquid Culture TN - True Negative 4. CBNAAT (Cartridge based Nucleic Acid Amplification Test) FP - False Positive 5. Line Probe Assay FN - False Negative 6. Tuberculin Skin Testing 4. NPV (Negative Predictive Value) 7. CxR NPV = d/(c+d) x 100 = TN/(TN+FN) x 100 8. LF-LAM Test –– Most serious error – FN 9. c-TB Test –– Most useful property : Test with highest sensitivity ROC (Receiver Operator Characteristic) CurveQ Trade off btw sensitivity & specificity Z line : no use Y line : Fair Fig 5: MTB X line : Good Uppermost line is taken as a cutoff for detection E. Screening Tests for HIV ERS battery of a disease in a population. 1. ELISA Test Upper the line , better the test. 2. Rapid Test 3. Simple Test Diagnosis: Western Block Assay Properties of Screening Test Disease present Disease Absent ST +ve TP (a) FP (b) ST –ve FN (c) TN (d) - Cases: a + c Controls: b + d 1. Sensitivity - Most UsefulQ Sens = a/(a+c) x 100= TP/(TP+FN) x 100 Fig 6: ROC 2. Specificity Spec = d/(b+d) x 100 = TN/(TN+FP) x 100 20 Cerebellum Quick Revision Notes Survival Analysis Measles - 10-14 days (10 days single best answer)Q Generally used for chronic disease like cancer Influenza - 18-72 hrs Kaplan Meiyer CurveQ Diphtheria - 2-6 days Upper curve : with treatment Cholera - 1-2 days Lower curve : without treatment Typhoid - 10-14 days Cancer with highest 5 – year survival post- screening is colonic cancer. Poliomyelitis - 4-33 days It has > 90 – 95 % survival if its pre-cancerous Hep A - 15-45 days stage FAP (Familial Adenomatous Polyposis) is Hep B - 45-180 days detected early & treatment is given. Staph FP - 1-6 hrs Dengue - 3-10 days F. Malaria - 12 daya Yellow Fever - 2-6 days JE - 5-15 days Trachoma(Rough eye) - 5-12 days Tetanus - 6-10 days (NNT 8th Day disease)Q HIV - 10 years Ebola - 2-21 days Fig 7: KM Curve Covid - 5-6 days Precision - ReliabililtyQ Periods of Communicability Repeatability/ Consistency/Reproducibility Measles (45) - 4 days prior to rash & 5 days Accuracy - Validity (Levy Jennings Chart)Q laterQ Close to true or actual value Chickenpox (25) - 2 days prior to rash & 5 days later UNIT 5 Diphtheria - 14-28 days from onsetQ TB - As long as not on Tx HIV - Lifelong Tetanus - None Covid - 3-5 days prior to symptoms & 8-10 days laterQ ICEBERG PHENOMENONQ 1. Tip : Cases Detected by – Diagnosis ( 2° level of prevention) Responsibility of clinicians COMMUNICABLE DISEASES AND NCDS 2. Hidden or submerged : Carriers / Subclinical/ Incubation Periods Preclinical / asymptomatic  21 PSM / Community Medicine Detected by – Screening ( 2°) Measles Responsibility of Epidemiologist –– Cause - RNA Paramyxovirus –– Pathological feature - Koplik spots –– IP - 10-14 days –– SAR - >90% –– Vaccine - Live attenuated Edmonston Zagreb strain ƒƒ Route - Subcutaneous 0.5ml ƒƒ 2 doses - 9 months & 16-24 months Fig 1: Iceberg Phenomenon –– Highest mortality among VPDs Line of demarcation – is in between Apparent and –– M/C Complication - Serous Otitis MediaQ inapparent –– Late complication - SSPE (Subacute No carriers – no Iceburg phenomenaQ Sclerosing Panencephalitis)Q eg ; Measles / Rubella / Rabies / Tetanus / Pertussis Respiratory Diseases Distribution of Rash on Body Smallpox –– Cause - Variola Major –– Centrifugal –– Eradicated - 8th May 1980 Fig 3: Koplik Spots Mumps –– Cause - Myxovirus Parotitis –– Affects commonly in children 5-9 years –– M/C complication - Aseptic Meningitis (overall) –– Adolescents - Orchitis(Males), Oophoritis(Female) –– Adult - Meningoencephalitis Fig 2: S.Pox, C.Pox Rash Chicken Pox aka Varicella –– Cause - HHV-3(→) –– Centripetal –– Pleomorphic Fig 4: Mumps –– Dew drop on rose petal Congenital Rubella Syndrome (CRS) –– Vaccine – live “OKA” strain 22 Cerebellum Quick Revision Notes Fig 5: CRS Microcephaly Diphtheria Sensory Neural Deafness Cause – Corynebacterium diphtheriae Patent Ductus Arteriosis (PDA) (Albert Stain)(Cuneiform appearance)Q Cataract Vaccine - DPT(Wks 6,10,14) –– Measles - Rubeola 1st booster - 16-24 mths, 2nd - 5 years –– Mumps - Rubula –– German Measles - Rubella German Measles (Rubella) Mode of Transmission 1. Resp (Air Droplets) 2. Trans Vaccine - Live Attenuated RA 27/3 Priority Group - Non-pregnant, Non-Lactating 15-49 years females Characteristic - Blueberry Muffin lesions Influenza Fig 7: Diphtheria Vaccine - Live - Intranasal v. Td - Tetanus-Diphtheria - 10 years, 16 years, Killed - A7/California/2009 Pregnant women. Fig 6: Intranasal Vaccine Fig 8: Td Vaccine  23 PSM / Community Medicine Covid 19 Detected - 31st Dec 2019, Wuhan, China Initially PUE ( Puemonia of unknown etiology) Nasopharyngeal swab RT-PCR(Gold Standard in India) Fig 9: Covid - 19 MucormycosisQ Anti HBe - Active viral replication stopped/ Marker of good prognosis Ribbon – Hyphae ( ANTLERS OF MOOSE APP;) Anti HBs - Marker of end of POC, DOC - LAMB vaccinated individual [HBVDNA - Most sensitive of AVR and infectivity] Typhoid Fig 10: Mucormycosis B. Hepatitis & Diarrhoeal Diseases Hepatitis Hep A- Infectious Hep, Major route : Fecal, oral Hep B - Serum Hepatitis Hepatitis B Serum MarkersQ Fig 11: Typhoid HBsAg - Australian Antigen (Epidemiological Marker) , First Ag to Enteric fever - Step-ladder fever appear. Cause - Salmonella Typhi HBcAg - rarely seen ( core antigen) Clinical features - Coated tongue, rose spots, HBeAg - high infectivity marker, active Pea soup stools/ diarrhea viral replication Mnemonic - BASU Anti HBc - Marker of Acute Hep B(IgM) 24 Cerebellum Quick Revision Notes –– B - Blood culture (1st wk) 3. Super ORS –– A - Ab Test(Widal) (2nd wk) Complex sugar –– S - Stool culture (3rd wk) –– Rice based –– U - Urine culture (4th wk) –– Alanine/glycine based Vaccine - Typhoral = Live attenuated, Ty21a –– Glucose polymer based strain, 3 year protection: D 1-3-5Q C. Worm Infestations Vaccine - Typhim :V1 = IM, polysaccharide, Rx - Cephalosporins/Fluoroquinolones/ORS 1. Hookworm ORS Route - Penetration of skin of foot Associations - IDA (0.1ml /W/day blood loss), Father of ORS - Dilip Mahalanabis Hypoalbuminemia 1. WHO Low Osm ORS Endemic Index - Chandler’s Index (Katokatz) Content >300=>Major public health problem­Q –– Sodium chloride 2.6g DOC - Albendazole –– Potassium Chloride 1.5g –– Sodium Citrate 2.9g –– Glucose 13.5 dissolve it in 1L water (use it before