SUMMARY-Nobody Is Immune

Summary-Nobody Is Immune(PCL WEEK 8)

1) Immune system

(A network of cells, tissues, and organs that work together to defend the body against attacks by pathogens)

First line of defence (Skin, Lysozyme, Clotting of blood, Mucus and cilia)

Second line of defence (innate immune system (non-specific) and adaptive immune system (specific); Involves leukocytes)

Immunity (Active and passive; Natural and Artificial)

Herd Immunity

If immunity rates in a society is high, then protection will aslo be conferred to those who are unvaccinated.

2) Pertussis

i) Incidence & Prevalence

According to age (US):

2001-2003

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1-4 years – 12 %

5-9 years - 9%

10-19 years – 33%

20 years - 23%

In Malaysia

Decrease after introduction of vaccine

0.02 per 100 000 population. (2006)

ii) Causes & Predisposing factors

Caused by a bacteria called Bordatella pertussis

Predisposing factors: Direct/Indirect Contact, Airbone droplets, Not being immunized.

iii) Pathophysiology
-Typically attacks children
-3 stages : Catarrhal àParoxysmalàConvalescent
Pathophysiology :
-Bordetella pertussis attaches to and multiplies on the respiratory epithelium. This damages ciliated respiratory epithelium.
-The damage starts in the nasopharynx and ends primarily in the bronchi and bronchioles
-Cilia is attacked by bacteria and with the accumulation of debris in the respiratory tract, mucus is produced
-As the body can’t get rid of the mucus in the airways, coughing and inhalation with a whistling or whooping sound entails.
-This causes difficulty in breathing
Whistling/whooping sound :
-Narrowing of the lower respiratory tract and is caused by mucus
-Air moves through the narrowed space, it sounds like whistling or whoosing.
-Often comes from the small breathing tubes (bronchial tubes) deep in the chest

iv) Complications & Symptoms

The first stage- runny nose, sneezing, low-grade fever, mild, occasional cough, similar to the common cold.

The second stage-Bursts (paroxysms) , breathing in accompanied by a characteristic high-pitched "whoop" sound, individual may become cyanotic (turn blue) from lack of oxygen, Children and young infants appear especially ill and distressed, Vomiting and exhaustion

The third stage -The cough becomes less paroxysmal and usually disappears

Complications -secondary bacterial pneumonia,seizures,encephalopathy,reactive airway disease,dehydration,malnutrition.

v) Differential Diagnosis

1. Asthma

Pertussis is also associated with vomiting and sputum. To confirm whether it is asthma or pertussis a definitive culture diagnosis or blood-work is done.

2. Pneumonia

Pertussis is not asscociated with joint pains and shaking chills. Hence, pneumonia is ruled out.

3. Tuberculosis

Lupus vulgaris and chroiditis is not associated with the symptoms of Pertussis. Hence Tuberculosis is ruled out.

4. Febrile Seizures

Pertussis is not associated with otitis media. Hence, Febrile seizure is ruled out.

Diagnosis:

Suggested clinically by the the characteristics of the whooping cough and a history of contact with an infected individual. It is confirmed by the isolation of the organism. Cultures or swabs of nasopharyngeal secretions result in a higher positive yield than cultures of ‘cough plates’.

Workup

Laboratory Studies - Blood work, Cultures, Direct fluorescent antibody (DFA) studies, Enzyme-linked immunosorbent assay (ELISA), Imaging Studies.

vi) Management & Treatment

Medical Care

· The goals of therapy include limiting the number of paroxysms, observing the severity of cough, providing assistance when necessary, and maximizing nutrition, rest, and recovery.

· Hospitalization-Monitor heart rate, respiratory rate, and oxygen saturation of hospitalized patients continuously, especially in relation to coughing paroxysms. Coughing, feeding, vomiting, and weight changes should be recorded.

· Pay attention to the young infant's hydration and nutritional status.

· Patients who are severely ill may require treatment in an ICU.

Medication - Antimicrobial agents, Pertussis-specific immune globulin ,Antibiotics(oral (PO) erythromycin, macrolide antibiotics(erythromycin, clarithromycin, and azithromycin, trimethoprim-sulfamethoxazole).

vii) Prevention – Maintain hygiene, Avoid contact with infected people, Isolation, Vaccination and Booster vaccination, Education.

3)Safety of vaccination & Immunisation schedule

1) Greatest success story in public health: reduction of infectious diseases resulting from the use of vaccines.
eg. Reduced preventable infectious diseases (measles, pertussis, diphtheria)

2) Prior to approval by FDA, vaccines are tested extensively by scientists to ensure they are effective and safe. But no vaccine is 100% safe or effective. (depends on individual immune systems)
- Mice, guinea pigs, rabbits, monkeys
- FDA approves clinical studies
- Human subjects (voluntary), computers used to predict how the vaccine will interact with the immune system
- 3 phases: small (20-100 volunteers) a few months,
larger (several hundred volunteers) months to years,
larger still (several hundreds to thousands) several years.

3) Agencies involved in vaccine safety regulation:
a) National Vaccine Program Office (NVPO) under National Childhood Vaccine Injury Act (NCVIA)
- Vaccine Adverse Event Reporting System (VAERS) by CDC and FDA in 1990
- National Vaccine Injury Compensation Program (NVICP)
b) Department of Health and Human Services (DHHS)
- Centers for Disease Control and Prevention (CDC),
- Food and Drug Administration (FDA)
- National Institutes of Health (NIH)
- Health Resources and Services Administration (HRSA).

4) Six Common Misconceptions By CDC 29 May 2007

Immunization Schedule (2007)

BCG (birth), DtaPHibHep(2,3,5 months), DTwPHib(2,3,5,18 months), HepB(birth,2,3,5 months),IPV(2,3 months), JapEnc(9,10,18 months;5,8,11,14 years), Measles ( 6months), MenACWY (Hajj Pilgrims), MMR(12 months;7 years), OPV (2,3,5,18 months; 7 years), TT(15 years), Typhoid(food handlers), YF (visitors to Yellow fever endemic countries)

4)Role of parents and government on protecting infectious diseases(Covered in Mock-Trial)

Role of Government:

· monitoring, analysing and reporting on vaccine preventable diseases (VPDs) as well as bacterial, bloodborne and sexually transmitted diseases

· providing timely, accurate and relevant surveillance advice to inform policy and response activities relating to VPDs, including pandemic planning

· providing stakeholders with information on the impacts that VPDs and other communicable diseases could pose to Australia, including through cross-jurisdictional and international trend analysis

· managing and contributing to committees on VPD and other communicable disease issues

· engaging data providers and stakeholders to enhance collection and collation of VPD information.

Role of family:(maintain hygiene, immunization, nutrition, healthy lifestyle)

5)Legal & social implications on not getting child immunised(Covered in Mock-Trial)

· Patients autonomy, Children and Young Persons Act 1933, Assessment of vaccination, Herd Immunity