Public Health Lecture Notes PDF

General epidemiology1 Dr. Nashwa Nabil lecturer of occupational and environmental kedicine Epidemiology is... Definition of Epidemiology(WHO),1998: “ the study of the frequency, distribution, determinants and dynamics of diseases or conditions in a defined population  Di...

General epidemiology1 Dr. Nashwa Nabil lecturer of occupational and environmental kedicine Epidemiology is... Definition of Epidemiology(WHO),1998: “ the study of the frequency, distribution, determinants and dynamics of diseases or conditions in a defined population  Distribution F+3D Determinants Dynamics  1- DISTRIBUTION Distribution of health related event in the population in relation to: person , time , and place characteristics (Distribution Triad) Describing the disease under study  person Time Place (Distribution Triad)  2- DETERMINANTS Mean etiology & risk factors of the disease. It include: agent factors , host factors and environmental factors. (Epidemiological triad)=(ecological triad) (Epidemiological triad) Agent Host Environment  3- DYNAMICS Mean chain of infection of the disease Ecology means the equilibrium that results from the dynamic interaction between host ,agent &environmental factor that help in maintaining the presence of the disease in the community. Epidemiological triangle It is triad of ecological factors that affect the occurance of the disease it consists of  Agent  Host  Environment  Heredity factors:  Age  Sex:  Occupation:sedentary life lead to C.V.D.  Socioeconomic conditions:-income  -education  -life style  -utilization of HS  Physical environment  Chemical environment.  Biological environment  Social and cultural environment 1. Sporadic cases 2. Endemic 3. Hyper-endemic 4. Epidemic 5. Outbreak 6. Pandemic 7. Enzootic 8. Epizootic Animal  Sporadic: Infrequent scattered cases not related to each other.  Endemic: A disease constantly present in the community due to the presence of its ecological factors (agent, host, environment) that help the maintenance of the disease.  Hyper Endemic: Endemic disease of high incidence and prevalence rates  Epidemic : Sudden increase in the number of cases of infectious disease in certain place and time than expected in that place and time.  Outbreak: Epidemic occurs in a confined group or closed community e.g. school, camp, hospital.  Pandemic: Epidemic of a particular infectious disease involving some countries of the world e.g. cholera, COVID-19.  Infection means invasion , growth, multiplication of a microbe in a host  Is the process through which an infectious agent is transmitted from source of infection to the susceptible host. I. Infectious agent. II. Reservoir (source of infection). III. Portal of exit. IV. Mode of transmission. V. Portal of entry. VI. Susceptible host.  Infectious agent. Susceptibl Reservoir e host Portal of Portal of entry exit Mode of transmissio n 1. Reservoir (source) of infection. 2. Modes of transmission. 3. Susceptible host.  General epidemiology2 Dr. Shimaa Gamal Lecturer of Public Health  Infectious process(chain) (epidemiological cycle) Is the process through which an infectious agent is transmitted from source of infection to the susceptible host. I. Infectious agent. II. Reservoir (source of infection). III. Portal of exit. IV. Mode of transmission. V. Portal of entry. VI. Susceptible host.  Infectiou s agent. Suscepti Reservoi ble host r Portal of Portal of entry exit Mode of transmissi on :Links of infectious cycle 1. Reservoir (source) of infection. 2. Modes of transmission. 3. Susceptible host.  I. Reservoir source of infection in which the organism live &multiply. It includes:- 1. Human reservoir (Cases or carriers) 2. Animal reservoir (Zoonosis) 3. Non-living reservoir (Soil, water, food, …….)  a. Cases.1 Those who get infected and show symptoms &signs of infection  b. Carrier.1 Persons who carry the organism in their bodies but show no symptoms or signs of infection. The organisms are excreted in their discharges and disseminate infection to others.  Importance of carrier 1. Move freely in the community. 2. Clinically healthy 3. Large number 4. infectivity period may be very long.  Types of carriers  Incubatory carrier  Convalescent carrier  Contact carrier  Healthy carrier Incubatory carrier  Cases become infective in the last few days of incubation period (before the onset of disease), e.g. cholera and typhoid, or in the last few weeks as (viral hepatitis). Convalescent carriers  Recovered cases continue to excrete the infective agents during the period of convalescence e.g. typhoid, cholera, diphtheria. Contact carriers  Contacts of cases (having high immunity) may be infected and transmit infection within two weeks, e.g. in case of typhoid. Healthy carriers  Contacts to polluted environment such as contaminated food or water (in endemic infectious diseases). Another Classifications of carriers  By the period of infectivity  By foci of infection  By the portal of exit  By flow of organism The period of infectivity  Transient: for few days (last days of incubation period (I.P.) e.g. cholera  Temporary: for few weeks or few months e.g. viral hepatitis A & B.  Chronic (permanent): for years e.g., incubatory carrier of AIDS. foci of infection  Respiratory carriers: carry organism in throat, nose, nasopharynx.  Gastro-intestinal carriers: carry organisms in gall bladder, small intestine, large intestine.  Urinary tract carriers.  Skin carrier. The portal of exit  Respiratory discharge: through coughing, sneezing, spitting.  Faecal carriers in food borne diseases.  Urinary carriers in typhoid and paratyphoid  Vomitus in cholera.  Skin discharge: mucous membrane and skin diseases.  Blood carriers: hepatitis B & C and AIDS.  Vertical transmission: in-utero infection, through breast milk. Flow of organism  Regular carriers: organisms always pass during the infectivity period.  Intermittent carriers: sometimes the organisms do not pass in the discharge during the infectivity period, e.g. in typhoid. Animal reservoir  Zoonosis: are group of diseases which primarily affect animals and can be transmitted to man.  Organisms come out with different discharges of animals.  Man gets infected by inhalation, ingestion, contact or insects. Examples of zoonosis 1. Cattle : brucellosis 2. Dogs : rabies 3. Cats : rabies 4. Poultry : salmonellosis, avian flu. 5. Fish :  NON-LIVING RESERVOIRS  Non living reservoirs of infection include water, food, and soil.  Water is the most dangerous.  often seen in countries with poor sanitation and low levels of personal hygiene.  Modes of transmission 1. Droplet (Air–borne) infection 2. Food–borne infection 3. Contact infection 4. Arthropod-borne infection (vector– borne diseases) 5. Occasional modes of transmission  Droplet (Air–borne) infection.1  Direct droplet: from the source to susceptible by direct contact.  Indirect method:  Air borne droplet nuclei or dust.  Contaminated articles & fomites. Droplet (Air–borne) infection  Predisposing factors of droplet infection: * Overcrowding * Bad ventilation * Bad health habits  Food–borne infection.2  Direct (fecal-oral) transmission: by human or animal excreta (hand to mouth).  Indirect (ingestion of contaminated food) through: ◦ Contaminated dust. Food–borne infection Examples of food borne infections: -  Bacterial: cholera, typhoid  Predisposing factors:  Poor environmental sanitation  Lack of supervision of food places and food handlers.  Bad health habits  3- Contact infection & STDs Organisms or parasites invade intact skin or mucous membrane e.g. in Bilharziasis, syphilis, ancylostomiasis, staph & strept. infection. Organisms invade injured skin or mucous membrane e.g. in wound infection, tetanus, gas gangrene, rabies.  4- Arthropod-borne infection (Vector–borne diseases) Mechanical transmission: the insect has no role in multiplication or development of the organism. Biological transmission: the insect plays an important role in multiplication and development of the organism to become infective.  4- Arthropod-borne infection (Vector–borne diseases) Insects of medical importance House flies: mechanical transmission of food borne diseases and eye infection. Mosquitoes - Anopheles in malaria - Culex in filariasis, rift valley fever. - Aedes aegypti in yellow fever. Tsetse flies (glossina): in trypanosomiass. Sand flies in leishmaniasis. Fleas in plague  5- Occasional modes of transmission Injection (parenteral) infection Blood transmitted Pyogenic infections Vertical transmission In-utero-infection: Peri-natal infection Lactation (breast feedings):  Injection (parentral) infection Blood transmitted - blood transfusion or -contaminated syringes or needles e.g. hepatitis B & C, AIDS, syphilis, CMV. Pyogenic infections: By contaminated syringes & needles e.g. staph. injection.  Vertical transmission  Vertical transmission: from mother to foetus or infant: 1. In-utero-infection: either before formation of placenta or transplacental e.g. hepatitis B & C, AIDS, syphilis, CMV. 2. Peri-natal infection: during labour through birth canal e.g. ophthalmia neo-natrum, herpes simplex. 3. Lactation (breast feedings): HBV, HCV, AIDS, CMV.  General epidemiology 3 Dr. Nashwa Nabil Lecturer of occupational &environmental medicine Benha faculty of medicine Exposed host Immunity (defence mechanism) Definition: defence mechanism (resistance) that protect the body from micro-organisms and harmful agents. I-General (innate) defence mechanism: Natural barriers: Skin, Eye, GIT, Respiratory system. II- Specific (acquired) immunity: a- Natural: i- Passive: Maternal immunity, Colostrum & breast milk. ii- Active: Clinical and sub-clinical disease. b- Artifitially induced: i- Passive: Seroprophylaxis. ii- Active: Vaccines and Toxoids.  General defense mechanism 1- Natural barriers of infection: Skin: Intact surface & bactericidel effect of sweat. Eye : Blinking reflex & tears prevent infection Respiratory system: sneezing & coughing reflexes. G.I.T: - Saliva & bacterial flora of mouth inhibit growth of microorganisms. -Gastric acidity (HCL) has bactericidal effect. -Intestinal flora of colon destroy microorganism.  Specific immunity Natural Acquired Passive Active Passive Active Transplacental Infection Immunoglobuli Vaccine Breast milk ns  Specific (Acquired) Immunity A – Naturally Acquired immunity: 1. Active natural acquired immunity : One attack of infection leads to different degrees of immunity: long lasting immunity e.g. measles, mumpes. 2- Passive natural acquired immunity : a- Transplacental materno- foetal immunity : (in the last weeks of pregnancy). IGg : small molecules can cross the palcenta. Give temporary immunity for 6-9 months. b- Colostrum & breast milk which contain: High contents of antibodies (IgA). B – Artificially acquired immunity Active artificially induced immunity: (Vaccines ) N.B: after active immunization of immune system, the response is either by humoral immunity (antibodies). Vaccine Definition : They are preparations of one or more types of organisms Types : Live vaccine: Live attenuated vaccines: Killed or inactivated vaccines:. Types of vaccines Live vaccine: Small pox vaccine prepared from cowpox virus Live attenuated vaccines: More potent than killed vaccines. Given for only one dose. Should not be given to pregnant women or persons with immunodeficiency disease. Examples: Measles, mumps, rubella (or MMR), sabin (OPV). Types of vaccines Killed or inactivated vaccines: Killed by heat or chemicals. Require primary series of 2-3 doses and some time booster dose. Given usually by intramuscular or subcutaneous injection. Examples : typhoid vaccine Route of administration of vaccines & toxoid Subcutaneous(S.C) or intramuscular (IM)  for most immunizations. ID (intradermal) Orally: sabin vaccine of polio (oral drops). Intranasal vaccine for influenza. System of active immunization: 1- Primary dose: Single dose only : e.g. MMR, measles, mumps, rubella. Multiple doses: e.g. OPV, HBV. 2- Booster dose: given after suitable period of time to individual or group at risk to maintain satisfactory level of immunity. Protective period of active immunization: Months e.g. cholera vaccine: for 6 ms. 2 years e.g. TAB vaccine for typhoid. 3-5 years e.g. DPT, TT. 5 years e.g. BCG vaccine. 10 years e.g. yellow fever vaccine. Solid (life long) immunity e.g. measles, mumps, rubella, MMR. Thank you  General epidemiology 4 Dr. Nashwa Nabil Lecturer of occupational &environmental medicine Benha faculty of medicine Mixed or combined vaccines: Salk DPT (quadriuple vaccine): salk + diphtheria + pertussis + tetanus. DPT: Diphtheria + pertussis + Tetanus. DT: Diphtheria + tetanus. MMR: Measles + mumps + Rubella. Cold chain: Is a system of vaccine storage and transport (at low temperature) during its journey from manufacture to consumer (equipments: freezer, vaccine carrying flask, ice packs).  Complications of active immunization (Hazards or side effects): 1-General reaction: as fever, malaise, headache, body aches. 2-Local reaction: pain, swelling, redness, tenderness, abscess. 3-General infection: due to contaminated syringes e.g HIV, HBV, HCV. Factors determining the effectiveness of active immunization in prevention of particular disease in the community: 1- Vaccine given: Protective value. Cold chain. 2- Process of immunization: Primary & booster immunization. Doses, spacing, route of administration. 3-Vaccination coverage: it should be at least 80 % (Satisfactory) Definition of vaccination coverage: The percent of at-risk individuals or groups that are actively immunized against particular disease by vaccine Passive artificially induced immunity (Seroprophylaxis) Definition: Passive artificially acquired immunity, induced by injection of already formed immunoglobulin, antibodies, and antitoxins to induce humoral or cellular immunity. Advantages and disadvantages: Give rapid but temporary protection. Used in prophylaxis or in treatment and before or after exposure to infection. Pattern of spread of infectious diseases Sporadic Endemic Hyperendemic Epidemic Pandemic Outbreak Thank you  Herd Immunity &Typhoid & para typhoid fever By Dr. Shimaa Gamal Mohammed Lecturer of public Health Faculty of Medicine Benha University ILOs:- ❑ Definition ❑ Agent ❑ Reservoir ❑ Exit ❑ Mode of transmission ❑ Communicability ❑ Incubation period ❑ c\p & complications ❑ Diagnosis ❑ Susceptibility & immunity ❑ Prevention & control  Definition ✓ Acute infectious, bacterial, food-borne disease characterized by systemic and intestinal manifestations. ✓ Called enterica Causative agent ✓ Bacteria called : Salmonella typhi ✓ Gram -ve, motile bacilli ✓ have 3 antigens (Ag): - O somatic -H flagellar - Vi virulence ✓ Killed by heat & disinfectants ✓ These bacteria can live in water, milk, faeces & food. Reservoir Man only 1- Cases 2- Carriers Carriers are classified as follows: 1- According to course of disease: - Incubatory - contact - convalescent - healthy 2- According to exit of infection: -urinary -intestinal(gall bladder) 3- According to regularity: intermittent 4- According to duration: -chronic -temporary Exit of the organism: urine and stools I.P: About 14- 17 days Period of infectivity: Starts from the last days of I.P and continues during the course of disease and period of convalescence.  Mode of transmission: feco-oral (food born disease) a. Direct :- Auto infection (hand- to – mouth). b. Indirect:- Ingestion of contaminated food or drink (from handling, containers, dust, house flies and cockroaches).  Clinical picture Prodromal Advanced Decline stage stage stage  Clinical Picture ❖ Prodromal stage (1 week) (bacterial invasion takes about 1 week). Step ladder Fever higher at night. Pulse is relatively slower to fever (bradycardia). Headache weakness, malaise, bone-ache and anorexia. Rash – rosy spots on the abdomen at the 6th or 7th day. ❖ 2- Advanced stage (2ws): ✓ High fever. ✓ Abdominal distension. ✓ Worse constitutional signs & symptoms Decline stage (4th week)  Gradual improvement.  Drop of temperature.  May be complicated or passes to convalescence.  Relapses may occur after 1-2 weeks of convalescence.  Convalescence: by drop of temperature to normal general condition.  Relapse – may occur after 1 or 2 weeks – rare + mild. Complications:  Intestinal (hemorrhage- perforation).  Cholecystitis, thrombophlebitis (femoral v.)  Pneumonia & myocarditis.  Osteomyelitis, bone abscess.  Fatality: 10% in complicated cases and < 2% in treated cases. Diagnosis ❖ Clinically: suggestive in late stage. ❖ Laboratory:  Blood culture (1st w.) +ve – confirm diagnosis - ve – not exclusive.  Widal test (2nd w.) – Rising titer – diagnostic - O- Ag – recent infection Susceptibility & immunity  Susceptibility All ages. summer months (higher incidence).  Immunity by  Sub clinical (mainly) and clinical infection  gives lasting immunity.  Vaccination (active immunization).  prevention & control A-General preventive measures: 1-Community development 2-Sanitation of the environment 3-Health education 4-Health promotion B- Specific prevention  by vaccination (3 vaccines) 1. TAB vaccine 2. Typhoid oral vaccine 3. conjugate polysaccharide vaccine  TAB vaccine Vi conjugate Oral ty21a polysaccharide vaccine Type Heat killed polysaccharide Live attenuated phenol inactivated Route of Subcutaneous Subcutaneous Oral, one capsule administration No of doses 2 1 3 Interval bet 4 weeks 2 days doses Booster 3 years 2 years 1 year.travelers 5 years.endemic S.E Local Not significant Not significant systemic Minimum age 6 months 2 years 6 years TAB vaccine Protective value: 60-75% for about 3 years. Nature: killed phenol preserved, each 1 ml contains 1000 million T(S. Typhi) and 750 million A & B (S. Paratyphi).  Target population: 1-Food handlers. 2-At risk occupation 3-Closed communities as camps, 4-Travelers to endemic areas and pilgrims. 5- At- risk communities during epidemics and outbreaks.  (Control (4 “C”s Control Cases Contacts Carriers Community Cases Early case finding treatment Notification Isolation Disinfection Release ( Follow up Treatment of cases  Choloramphenical 500 mg/4 h hrs. until fever subside  then 500 mg/ 6hrs for 2 weeks.  After one week rest – give ampicillin 500 mg/6 hrs. for one week. Release of case  After 3 negative stool or urine cultures  24 hours or more apart Control of carriers:  Recognize the carriers by bacteriologic diagnosis during pre-employement examination  Examination of contacts  Trace the source of infection  Treatment of carriers  Periodic laboratory investigation after release  Health education to follow clean habits.  Not to be licensed to work in food handling Treatment of carrier  In chronic gall bladder: Ampicillin for 1-3 months, other wise, and cholecystectomy.  In chronic urinary carrier: surgical removal of the pathological focus. Control of contacts Enlistment Investigation of contacts Specific protection (Vaccination) Surveillance (2WKs) Segregation (food handler) Health education and release Epidemic measures:  Environmental sanitation.  Health education.  Early case- finding and application of all measures to cases.  Epidemiologic study to trace source and channel of infection.  Paratyphoid fever  I- Epidemiology: The same as typhoid fever, but differs in:  Causative agent: S. Paratyphi A, B & C.  IP: shorter.  Onset: Sudden, especially in children.  Complications: Less frequent.  II- Prevention &Control: The same as typhoid fever.  Viral Hepatitis By Dr. Basma Hani Lecturer of public Health Faculty of Medicine Benha University  Viral Hepatitis Definition: inflammation of liver caused by viral infection Causes of viral hepatitis virus B Hepatitis (HBV) ILOs:-  Definition  Agent  Reservoir  Exit  Mode of transmission  Communicability  Incubation period  c\p & complications  Diagnosis  Susceptibility & immunity  Prevention & control  Definition  Viral hepatitis characterized by long I.P. Causative agent  Virus called : HBV “Hepatitis B Virus”  DNA virus  More resistant to heat and disinfectants than virus A.  HBV has 3 antigenic components each produces a specific antibody (Hepatitis Markers) ‫داااا‬%‫هام ج‬:- (Hepatitis Markers) 1- HBsAg (Hepatitis B surface antigen): indicates current infection 2- HBsAb (Hepatitis B surface antibody): Indicates patients recovered from acute hepatitis or individuals immunized With HBV vaccine. 3- HBc Ag (Hepatitis B- core antigen): cannot detected in blood. Detected only in liver 5-HBe Ag (Hepatitis envelope antigen): tissue indicates high Infectivity. 6-HBe Ab (Hepatitis envelope antibody): 4- HBcAb (Hepatitis B core antibody): indicates low infectivity and good prognosis indicates past infection Reservoir Man only 1- Cases 2- Carriers  Incubatory : infective for weeks.  Convalescent (chronic carrier): for years or life long  Healthy (chronic carrier): for years Exit of the organism: blood & body fluids I.P: 6 weeks- 6 months (usually 3 months) Period of infectivity: 1st 1-2 weeks of I.P + Course of disease + Convalescence period.  Mode of transmission: A- Horizontal : B- Vertical: Congenital infection 1- Exposure to infected blood: from HBsAg positive pregnant a. Parenteral route (syringes). mother to her fetus. b. Professional exposure. c. Traditional procedures and faulty habits (circumcision, tattooing & scarification). d. Attendants of dental clinics. e. Blood transfusion. 2- Organ transplantation and renal dialysis. 3- Other routes: - sexual contact  Clinical Picture - Insidious onset. - A febrile. - Pre-icteric phase. “ relatively benign” - Icteric & post- icteric stage: similar to HAV. Complications: i- Development of chronic carrier ii- Fulminate hepatitis. iii- Chronic hepatitis. vi- Liver cirrhosis. v- Liver malignancy (Hepatoma) = (HCC).  Diagnosis  Clinically: usually non-diagnostic. - Laboratory: 1- Detection of Hepatitis markers especially :  HbsAg which indicates active or past infection.  Anti HBcAg 2- HBV DNA by PCR is most sensitive test.  Susceptibility & immunity  Allages are susceptible.  No seasonal incidence.  Immunity follows: an attack or immunization.  Outbreaks may occur on mass exposure to infected blood.  Risks of seroconversion (infection) due to sharps injury from a known positive virus source : HBV 30% HCV 3% HIV 0.3% N.B. risk for HBV applies if not HBV vaccinated  prevention & control A-General preventive measures: 1- Precautions against exposure to infected flood: by  Use of disposable syringes & needles.  Sterilization of surgical and dental instruments.  Professional protection (PPEs) e.g. gloves.  Blood & blood products should be virus-free & sterilized by UVR.  Precautions with blood donors:- e.g i. Donors selection after blood testing for HBsAg. ii. Exclusion of drug-dependent donor and those who had hepatitis before. 2- Prevention of sexual transmission : by  Health education: to follow clean habits.  Avoid exposure : to known cases of disease.  B- Specific prevention Active immunization: by 1-Hepatitis B vaccine (Yeast-recombinant vaccine):- Dose and Administration: of hepatitis B vaccine - 3 doses, 0.5ml each, IM in deltoid region in adults and in the anterolateral aspect of the thigh in infants 1st dose after 1 month 2nd dose after 6 months 3rd dose. (i.e. doses 0,1,6) Protective value: 90% for 7 years. Application:  Medical and paramedical personnel.  Medical and paramedical students.  Groups needing repeated blood transfusion.  Infants: compulsory vaccination at 2, 4 & 6 months.  Sexual contacts of HBV patients or carriers  prisoners N.B :- Combined HAV and HBV vaccine Twinrix®, the hepatitis A and hepatitis B combination vaccine for people 18 years of age and older.  B- Specific prevention Active immunization: by 2-Seroprophylaxis (by Human specific hepatitis immunoglobulin ( Ig. ):- Application: 1. High- risk groups to prevent post-transfusion infection and jaundice. 2. New-bornes to HBsAg +ve mothers to prevent carriers and hepatoma :- Dose: 0.5 ml Ig IM within 12 hrs. of birth & at 3, 6 months. 3- Combined seroprophylaxis (Ig) and vaccination (given at same time but in different arms): given to a- Infants borne to infected mothers :  A single dose of HBIg is given within 12 hrs of birth IM. + - Vaccination is given at the same time with HB Ig as 0.5 ml IM (as a first dose) then, 2 nd dose at “1” ms and 3rd dose at “6” ms. of age. b- Post-exposure to infection (as medical staff needle stick injury or sexual exposure): - If vaccinated before test for anti-HBs Ig and if adequate (> 10 IU) give a nothing.  If vaccinated before test for anti-HBs Abs and if inadequate (< 10 IU) give a dose of HBIg and a booster dose of vaccine later. - If not vaccinated before give a dose of HBIg and 1 st dose of vaccine (at the same time), then 2nd dose after one month and 3rd dose after 6 months.  Poliomyelitis By Dr. Shimaa Gamal Lecturer of public Health Faculty of Medicine Benha University ILOs:- ❑ Definition ❑ Agent ❑ Reservoir ❑ Exit ❑ Mode of transmission ❑ Communicability ❑ Incubation period ❑ c\p & complications ❑ Diagnosis ❑ immunity ❑ Prevention & control  Definition ✓ Acute viral infectious food- borne disease which can cause Acute Flaccid paralysis (AFP). Causative agent ✓ virus called : polio virus ✓ Picorna virus (small RNA virus) ✓ - have 3 antigenic types: - Epidemics - Endemic cases - Sporadic cases ✓ - No cross immunity between these types. ✓ - Survive for long time under suitable conditions and relatively resist to the environment. ✓ - Killed by boiling and chlorination. ✓ - Neurotrophic Reservoir Man only 1- Cases : All clinical cases (in apparent, mild & moderate). 2- Carriers : All types (incubatory, contact, convalescent & healthy), all carriers are temporary (No chronic carriers) in endemic areas, healthy carriers are more common due to environment pollution. Exit of the organism: - Throat secretions from pharynx. (pharyngeal focus) - Stools from small intestine. (intestinal focus) I.P: 7- 14 days Period of infectivity: A- Case: The last days of I.P + course of disease + different periods in convalescence (1-2 ws in pharyngeal focus & 6-8 ws in intestinal focus). B- Carrier: healthy and contact carriers will remain infective for 1-2 weeks. Mode of transmission: bimodal :-droplet or feco-oral a. Droplet infection ( direct- oral to oral infection): :- Occurs in developed countries where the environment is sanitary. b. Ingestion infection (Feco- oral): -Direct :- autoinfection (Hand – to mouth) -Indirect :- Ingestion of contaminated food, water or milk. occur In developing countries only  Clinical picture I- Inapparent II- Clinical poliomyelitis infection (apparent) 1- Minor illness (Abortive type) I- Spinal poliomyelitis 2- Major illness or (CNS involvement) II- Bulbar poliomyelitis a- Paralytic b- Non III- Bulbo- Form paralytic form spinal poliomyelitis  Clinical picture I-Inapparent infection Non-manifested. Association with acquired immunity and carrier state 100 times more common than clinical type.  Clinical picture II- Clinical poliomyelitis (apparent) 1- Minor illness (Abortive type) - Forms the majority of clinical cases. - Shows mild manifestations for 1-2 days, then clears up producing immunity. - Manifestations include: a- Moderate fever. b- GIT: vomiting, diarrhea, abdominal pain and constipation. c- RT: respiratory catarrh, pharyngitis & sore throat.  Clinical picture II- Clinical poliomyelitis (apparent) 2- Major illness or (CNS involvement) Paralytic Form Non paralytic form *Manifestations of minor illness: -Moderate fever. -G/T: vomiting, diarrhea, abdominal pain, constipation. -RT: catarrh, pharyngitis & sore throat. * Signs of meningeal irritation (meningism) and Aseptic meningitis (pain and stiffness of the neck, back and limbs). *prognosis: cure or paralysis Paralytic form: - 7-10 days from the onset of disease. - Motor nerve cells are destroyed (but not sensory). - No sensory loss. According to area of CNS affected, it may be: 1-Spinal poliomyelitis: Anterior Horn cells (AHCs) of spinal cord are destroyed causing Flaccid paralysis. Mainly in lower limbs. No sensory loss. 2-Bulbar poliomyelitis: Motor Nuclei of cranial nerves are destroyed (6,10,11) leading to: - Dysphagia: (10th Cranial nerve). - Diplopia: (6th CN). - Nasal tone of voice and regurgitation of fluids from the nose (11th CN). - Involvement of respiratory center (shallow irregular respiration) - Involvement of vasomotor center (blood pressure rise then fall) 3- Bulbospinal polio Predisposing factors for CNS Injury : 1- Surgery: Tonsillectomy, Adenoidectomy & teeth extraction. 2- IM injection. 3- Fatigue, excessive muscle activity. 4- Pregnancy in non-endemic areas. Complications of Poliomyelitis :  Soft tissues (muscle) and bone deformity.  Infection (respiratory, myocarditis & urinary).  Fatality: 2-10% (from bulbar form). Diagnosis ❖ Clinically: not diagnostic except: paralytic and non- paralytic. ❖ Laboratory: 1- Isolation of virus from throat washing and stools. 2- Serologic testing of neutralizing antibodies (Rising titre is diagnostic). immunity to polio  Immunity by 1- Naturally acquired. 2- after clinical and sub-clinical infections. 3- Artificially induced: From the mother (remains 6ms), seroprophylaxis and active immunization.  Prevention & control a-General prevention: 1-Environmental Sanitation (Food control and Safe water supply). 2-Health education 3-Health promotion 4-Community development B- Specific prevention : by 1- Seroprophylaxis (passive immunization): by * Human immunoglobulin (Ig), 0.3 mg/ kg, IM leads to rapid protection for short duration. * It is given shortly after or before exposure. It is given to : a-Exposed pregnant women b- Lab. Workers on accidental exposure. c- Before throat & nose surgery during out breaks. 2- Vaccination (Active immunization): by 2 vaccines, Sabin and Salk i- Sabin vaccine : * Nature: Live - attenuated ( Human diploid cell culture). * Dose and administration: 3 drops, orally. * Frequency: Primary: 3 doses at 2,4, 6 months then Booster dose: 18-24 months & at school entry. * Action: 1- Humoral immunity: Neutralizing Ab in serum. 2- Cellular immunity: local immunity in intestinal. mucosa. * Protective value: 95% protective immunity. *Contra-indications : Acute infectious diseases, Fevers, Diarrhea , Dysentery, Leukemia, pregnancy & Corticosteroid therapy. ii- Salk vaccine: Nature: Formalin inactivated (kiiled) vaccine (monkey kidney culture). Dose and administration: 0.1 ml SC or IM Frequency: 4 doses starting at age of 4 months, (1st dose 6-8 weaks 2nd dose 6-8 weaks 3rd Action: only Humoral immunity (neutralizing Abs) prevents paralytic type only but not non paralytic as it does not prevent virus replication in the intestine. dose 4th). Protective value: 80% protective immunity. Contraindication: should be avoided during epidemics because injections increase incidence of paralysis Advantages of sabin: 1. Easy administration (oral). 2. Double immunity. 3. Useful in controlling epidemics. 4. No need for trained personnel. 5. The vaccine strain passes in feces & is disseminated in environment and can be transmitted to non- immunized children by feco-oral route. This leads to spread of immunity in the community (herd immunity).  Application of salk: ( in non-endemic areas) 1- Mass immunization of infants & children. 2- During pregnancy leads to newborn with acquired immunity. 3- A substitution of sabin vaccine. 4- Susceptible travelers to endemic areas. 5- Could be given to immune compromised (such as HIV) as it is killed vaccine. Polio vaccination in Egypt : 1. EPI system (Expanded Program on Immunization). ‫البرنامج الموسع للتحصين‬ 2. Polio vaccination campaign: (periodic campaign).  Control of Polio (3 “C”s) Control Cases Contacts Community Control of cases: 1. Case finding. 2. Notification: LHO (local health authority) and WHO. 3. Isolation :suspected or confirmed case should be isolated at hospital for six weeks after onset of symptoms or until polio virus can no longer be detected in the faeces. 4. Disinfection: - concurrent (resp. discharge & stools) - Terminal 5. Treatment: of paralytic cases. 6. Rehabilitation. Control of contacts: 1- Enlistment : personal history. 2- Surveillance : examination for case finding. 3- Seroprophylaxis. 4- Health education Epidemic measures: at time of outbreaks 1- Mass oral immunization of children (sabin). 2- Epidemiologic studies to trace source and channel of infection. 3- Postpone active immunization by injection (salk). 4- Postpone throat or nose surgery. 5- Active Surveillance for acute flaccid paralysis cases for at least 2 incubation periods beyond the onset of the last case in the area. * Polio. Eradication : 1. Immunization coverage; At least 90% of children under 1 year should receive a full course of polio immunization (At 1st immunization). 2. Surveillance. 3. Epidemic measures. 4. Aggressive outbreak attack  Public health - final lecture (Revision) ​ 1.​ Links of infectious cycle does NOT include?​ A) Reservoir of infection​ B) Environment ​ C) Mode of transmission​ D) Susceptible host​ 2.​ The most dangerous non-living reservoir is? ​ A) Food​ B) Water ​ C) Fomites​ D) Soil​ 3.​ A convalescent carrier is?​ A) A person who transmits the agent prior to the onset of disease​ B) An animal carrier​ C) An infected person who has recovered from disease but still harbors and transmits the agent ​ D) None of the above​ 4.​ Sudden abnormal increase in number of cases in a closed community is defined as?​ A) Endemic​ B) Epidemic​ C) Pandemic​ D) Outbreak ​ E) Sporadic​ 5.​ The equilibrium that results from the dynamic interaction between host, agent & environmental factors that help in maintaining the presence of the disease in the community is?​ A) Epidemiology​ B) Demography​ C) Ecology ​ D) Bibliography​ ​ ​ 6.​ The typical pattern of fever in Typhoid is?​ A) Intermittent fever​ B) Relapsing fever ​ C) Step ladder fever​ D) Pel-Ebstein fever​ E) Malta fever​ 7.​ The rash seen in typhoid patients is referred to as? ​ A) Koplik's spots​ B) Rosy spots ​ C) Flame spots​ D) Dew Drops spots​ 8.​ The blood test done to diagnose typhoid is called?​ A) ELISA test​ B) Widal test ​ C) Western Blot test​ D) TORCH test​ E) Tuberculin test​ ​ ​ ​ ​ ​ 9.​ The poliovirus infection is spread through?​ A) Breastfeeding​ B) Feco-oral route ​ C) Placental route​ D) Sexual route​ E) Arthropod borne route​ 10.​Paralytic form of poliomyelitis is characterized by?​ A) Spastic paralysis​ B) Meningism​ C) Upper limb affection mainly​ D) No sensory loss ​ E) Facial nerve affection (7th Cranial nerve)​ 11.​Cases of typhoid fever discharge their organisms through?​ A) Respiratory discharge​ B) Blood​ C) Urine and stool ​ D) Sweat​ ​ 12.​Control measure for contacts to typhoid cases included? ​ A) Human immunoglobulin administration​ B) Surveillance for 1 week​ C) Segregation if food handler​ D) Cholecystectomy​ 13.​Transplacental immunity transmitted from mother to fetus?​ A) Ig A​ B) Ig G ​ C) Ig M​ D) Ig B​ 14.​A system of vaccine storage and transport during its journey from manufacturer to consumer to preserve it is?​ A) A transfer chains​ B) Cold chain ​ C) Performed at high temperature​ D) All of the above​ 15.​The presence of Hepatitis B envelope antibody markers in blood indicates?​ A) Current infection​ B) Low infectivity and good prognosis​ C) High infectivity​  ​ 16.​Risk of seroconversion (infection) due to sharp injury from a known HBV positive source is? ​ A) 300%​ B) 30% ​ C) 3%​ D) 0.3%​ E) 0.03%​ 17.​The most sensitive test for diagnosis of HBV infection is?​ A) Detection of HB surface Ag​ B) Detection of HB core Ag​ C) Detection of HBV DNA by PCR ​ D) Detection of HBV RNA by reverse PCR​ 18.​Gastric acidity is a? ​ A) Specific defense mechanism​ B) General defense mechanism ​ C) Active natural immunity​ D) Passive natural immunity​ 19.​The type of oral polio vaccine (Sabin vaccine) is? ​ A) Killed vaccine​ B) Live attenuated vaccine ​ C) Inactivated vaccine​ D) Recombinant vaccine​ 20.​All are true about the Salk vaccine except?​ A) It prevents paralysis.​ B) It is a killed vaccine.​ C) It induces immunity? humoral and intestinal ​ D) Could be given to immunocompromised​ ​ ​ 21.​One of oral polio vaccine (Sabin vaccine) advantages is? ​ ​ A) Could be given to immunocompromised and HIV patients.​ B) Given during pregnancy leads to newborn with acquired immunity​ C) Killed inactivated vaccine that doesn't require stringent conditions during storage and transportation.​ D) Can be transmitted to non-immunized children by feco-oral route, producing herd immunity ​  ​ 22.​Which of the following is a physical causative agent that affects health?​ A) Climate ​ B) Customs​ C) Habits​ 23.​This vaccine is considered as having absolute protective value?​ A) MMR ​ B) Cholera vaccine​ C) Tetanus vaccine​ D) TAB​