finals exam

• Bordetella pertussis


  • Gram-negative pleomorphic bacillus
  • Main causative organism for pertussis
  • Humans are the sole reservoir for B. pertussis and B. parapertussis
  • Pertussis is highly contagious → developing in approximately 80-90% of susceptible individuals who are exposed

  
• Outbreaks of pertussis first described

  16th century

  
• Bordetella pertussis isolated


  1906

  
• Pertussis


  • Primarily a toxin-mediated disease
  • Bacteria attaches to the cilia of the respiratory epithelial cells → produce toxins that paralyze the cilia
  • Causes inflammation of the respiratory tract, which interferes with the clearing of pulmonary secretions
  • Until recently, scientists thought that B. pertussis did not invade the tissues. However, recent studies suggest that the bacteria are present in alveolar macrophages

  
• Symptoms of whooping cough

  • Violent cough fits
  • Runny nose
  • Nasal congestion
  • Vomiting
  • Watery red eyes
  • Mild fever
• Transmission of pertussis and respiratory diphtheria

  Respiratory droplets (i.e., from coughing or sneezing)

  
• Preventive measures for pertussis

  1. Observe respiratory hygiene when sneezing and coughing

  2. Individuals who are unvaccinated or have not completed their vaccination series or are at increased risk of severe illness should avoid or limit contact with individuals with known or probable pertussis

  3. In household settings, practice standard precautionary measures such as mandatory hand washing with soap and water as well as hand hygiene using alcohol-based sanitizer

  4. In health facilities, health workers should strengthen infection prevention and control measures by observing standard precautions complemented by droplet precautions

  
• Clinical case definition for pertussis

  In the absence of a more likely diagnosis, a cough illness lasting ≥2 weeks with at least one of the following signs or symptoms: Paroxysms of coughing, Inspiratory "whoop," Post-tussive vomiting, or Apnea (with or without cyanosis)

  
• Laboratory criteria for diagnosis of pertussis

  • Isolation of B. pertussis from a clinical specimen
  • Positive polymerase chain reaction (PCR) for B. pertussis
  • Epidemiologic linkage - Contact with a laboratory-confirmed case of pertussis

  
• Probable case classification for pertussis

  In the absence of a more likely diagnosis, illness meeting the clinical criteria, OR Illness with cough of any duration, with at least one of the following signs or symptoms: Paroxysms of coughing, Inspiratory "whoop", Post-tussive vomiting, or Apnea (with or without cyanosis) AND Contact with a laboratory-confirmed case (epidemiologic linkage)

  
• Confirmed case classification for pertussis

  Acute cough illness of any duration with: Isolation of B. pertussis from a clinical specimen, OR PCR positive for B. pertussis

  
• Culture


  • Use during the first 2 weeks following cough onset; sensitivity decreases and the risk of false negatives increases after 2 weeks
  • Gold standard for pertussis diagnosis
  • The gold standard because it is the only 100% specific method for identification

  
• Specimen collection for pertussis

  1. Qualified for Specimen Collection: All suspect/clinical cases of Pertussis who fits the case definition

  2. Appropriate Sample: Nasopharyngeal Swab (NPS) or Nasopharyngeal Aspirate (NPA)

  3. Materials Needed: Sterile polystyrene, rayon, or nylon flocked swabs, Universal Transport Medium (UTM), Regan Lowe or Cryovials

  4. Timing of Collection: Specimens should be collected prior to antimicrobial therapy; collected during the first 3 weeks of illness following cough onset, but PCR may provide accurate results on specimens collected up to 4 weeks

  5. Method of Collection: Proper technique for obtaining an NP specimen for isolation

  
• Storage and handling of pertussis specimens

  1. For swab in transport medium: Collect from patient and immediately place in Universal Transport Medium (UTM) and store within 30 minutes of collection, refrigerated (2-8°C) until shipment

  2. For swab only (dry swab): Collect from the patient and immediately place in a dry, sterile tube and store frozen (-20°C or lower) within 30 minutes of collection

  3. For nasopharyngeal aspirate: Immediately place in leak-proof plastic tube and store within 30 minutes of correction, refrigerated (2-8°C) if it will be shipped within 72 hours of collection; otherwise, freeze the aspirate (-20°C or lower) within 30 minutes of collection
• Transportation of pertussis specimens

  1. If the specimen was stored refrigerated, ship with refrigerated or frozen cold packs within 24-72 hours of collection

  2. If the specimen was stored frozen, ship frozen overnight with dry ice within 1 week of collection. Once the specimen is frozen, do not allow the swab to thaw

  3. Observe Triple Packaging Guidelines

  4. All specimens collected must be brought to the accredited National Reference Laboratory or Research Institute for Tropical Medicine (RITM), Alabang, Muntinlupa City for confirmation
• Diagnostic/Laboratory tests for pertussis

  • Culture: Use during the first 2 weeks following cough onset; sensitivity decreases and the risk of false negatives increases after 2 weeks. Gold standard for pertussis diagnosis because it is the only 100% specific method for identification
  • PCR: Use up to 3 to 4 weeks following cough onset. The most rapid test available
  • Serology: Use 2 to 8 weeks following cough onset for optimal results but can be used up to 12 weeks following cough onset. Can be performed much later than culture and PCR, more useful later in the course

  
• Gold standard for pertussis diagnosis

  The only 100% specific method for identification
• Timing of specimen collection for culture

  1. Ideally, specimens should be collected during the first 2 weeks of illness following cough onset

  2. After the first 2 weeks, sensitivity decreases and the risk of false negatives increases

  3. If culture is planned, directly plate the collected NP swab or immediately place it into the transport medium

  4. Laboratory scientists should plate NP swabs and aspirates within 24 hours of collection

  
• Culture


  Better specificity than PCR, but takes up to 7 days to obtain results
• PCR


  • Use up to 3 to 4 weeks following cough onset
  • The most rapid test available

  
• Serology


  • Use 2 to 8 weeks following cough onset for optimal results but can be used up to 12 weeks following cough onset
  • Can be performed much later than culture and PCR, more useful later in the course of the disease

  
• Contact Tracing and management

  Should be done for clusters of cases and confirmed cases with close contacts defined as people who: had face-to-face exposure to a case, which includes household or family contacts, had stayed overnight in the same room with a case and had direct contact with respiratory, oral or nasal secretions with a laboratory-confirmed case
• Asymptomatic close contact


  Implement daily monitoring for 21 days after the last exposure to a probable or confirmed case for the development of signs and symptoms of pertussis

  
• Prophylaxis of identified close contacts

  All asymptomatic household close contacts are recommended to be given antimicrobial prophylaxis within 21 days of the onset of cough in the index patient

  
• Transmission requires close contact (exposure within 1 meter for more than 1 hour) but can be less for young infants
• Individuals considered high risk if exposed within 21 days to an infectious pertussis case


  • Infants under 12 months of age
  • Women in their third trimester of pregnancy
  • Individuals with pre-existing health conditions (e.g., immunocompromised, with moderate to severe medically treated asthma, etc.) that may be exacerbated by a pertussis infection
  • Individuals who have a high probability of having close contact with high-risk individuals
  • Individuals in high-risk settings that will have close contact with infants under 12 months of age or women in the third trimester of pregnancy (e.g., neonatal intensive care units, childcare settings, and maternity wards)
• However, the administration of PEP is appropriate in limited closed settings
• Health workers should monitor individuals exposed to pertussis for onset of signs and symptoms for 21 days

  
• Community diagnosis


  The process through which health workers together with members of the community identify the community's priority health problems and together make plans of action and implement them
• Concepts of primary health care that the community's full participation depends on

  • Acceptability
  • Accessibility
  • Affordability
  • Availability
• Purpose of community diagnosis

  • Collect information on demography including health statistics
  • Causes of morbidity and mortality by age and gender
  • Use of group services especially MCH/FP
  • Nutrition, diet, and weaning patterns of the community, growth of pre-school & school children
  • Societal culture and social economic stratification
  • Mental health and assessment of the possible cause of mental illness
  • Patterns of leadership and communication within the community
  • State of the environment including water, housing, and disease vectors
  • Community's Knowledge, attitude and practices in relation to health-related activities
  • Epidemiological details of endemic diseases
• Tools used in community diagnosis

  • Maps
  • Weighing scale
  • Specimen bottle
  • Questionnaires
  • Health Indicators - variables used for the assessment of community health
• Characteristics of health indicators

  • Valid - should measure what they are supposed to measure
  • Reliable and objective - the answers should be the same if measured by different people in similar circumstances
  • Sensitive - they should be sensitive to changes in the situation concerned
  • Specific - they should reflect changes only in the situation concerned
  • Feasible - they should have the ability to obtain data needed
  • Relevant - they should contribute to the understanding of the phenomenon of interest
• Classification of health indicators

  • Mortality indicators
  • Morbidity indicators
  • Disability rates
  • Nutritional status indicators
  • Health care delivery indicators
  • Utilization rates
  • Indicators of social and mental health
  • Environmental indicators
  • Socio-economic indicators
  • Health policy indicators
  • Indicators of quality of life
  • Other indicators
• Mortality indicators


  • Mortality Rates
  • Crude death rates
  • Specific death rates: age/disease
  • Expectation of life
  • Infant mortality rate
  • Maternal mortality rate
  • Proportionate mortality ratio
  • Case Fatality rate
• Morbidity indicators


  • Incidence and prevalence
  • Notification rates
  • Attendance rates: out-patient clinics or health centers
  • Admission and discharge rates
  • Hospital stay duration rates
• Disability indicators


  • No. of days of restricted activity
  • Bed disability days
  • Work/School loss days within a specified period
  • Expectation of life free of disability
• Healthcare delivery indicators


  • Doctor / Population ratio
  • Doctor / Nurse ratio
  • Population / Bed ratio
  • Population / per health center
• Healthcare utilization indicators


  • Proportion of infants who are fully immunized in the 1st year of life
  • Proportion of pregnant women who receive ANTENATAL CARE
  • Hospital-Beds occupancy rate
  • Hospital-Beds turn-over ratio
• Social and mental health indicators

  • Suicide & Homicide rates
  • Road traffic accidents
  • Alcohol and drug abuse