Paediatric Infectious Disease Presentation DR ELHAM BUKHARI Consultant

Paediatric Infectious Disease Presentation DR. ELHAM BUKHARI Consultant Paediatric Infectious Disease Paediatric Department King Khalid University Hospital

Immunization. -Is the process by which an individual's immune system becomes fortified against an agent (known as the immunogen).

Immunization. • The most important elements of the immune system that are improved by immunization are the B cells (and the antibodies they produce) and T cells. • Memory B cell and memory T cells are responsible for a swift response to a second encounter with a foreign molecule.

• Active Immunization: Administration of all or part of a microorganism or a modified product of that microorganism i. e. a toxoid, a purified antigen, or an antigen produced by genetic engineering→to evoke an immunologic response mimicking that of the natural infection but that usually present little or no risk to the recipient.

Active Immunization: • Vaccines incorporating an intact infectious agent may be either live (attenuated) or killed (inactivated).

what are the advantages of a live attenuated vaccine? • -They act like the natural infection with regard to their effect on the immune response-Immunity develops slowly. -Stimulates longer lasting antibody production-used for long term prophylaxis. -induce antibody production and resistance at the portal of entry for the natural virus

Active Immunization • Types • Live attenuated: • Virus: Measles, mumps, rubella, OPV • Bacteria: BCG

Killed • Virus: Hepatitis B • Bacteria: • Whole. Pertussis • Toxoid. Tetanus • Polysaccharide. Meningoccocal

• Why we need booster doses? • Inactivated and sub-unit preparation are incapable of replicating in the host, these vaccines must contain a sufficient antigenic mass to stimulate the desired response maintenance of long-lasting immunity with inactivated viral or bacterial vaccines often requires periodic administration of booster doses.

• Passive immunization Administration of performed antibody to a recepient e. i. 1. When persons are deficient in synthesis of antibody as a result of congenital or acquired B-lymphocyte defects, alone or in combination with other immunodeficiencies. 2. When a person susceptible to a disease is exposed to or has a high likelihood of exposure to that infection, especially when that person has a high risk of complication from the disease i. e. a child with leukemia exposed to varicella or measles.

• Passive immunization • Immune globulin (IG) and specific hyper immune globulin given intramuscularly i. e. hepatitis B immune globulin (HBIG) q. Immunoglobulin intravenous (IGIV) and specific hyper immune IG given by intravenous (IV) route i. e. respiratory syncytial virus IGIV-(RSV-IGIV), human plasma and antibodies of animal origin.

Human Immune Serum Globulin • Specific • • • IMHepatitis B (HBIG) Rabies (RIG) Tetanus (TIG) Varicella (VZIG) IVCMV (CMV-IG) RSV (RSV-IG)

• Active immunization of persons who recently received immune globulin q. Live-virus vaccines given parenterally can have diminished immunogenicity when given shortly before or during a period of several months after receipt of immune globulines q. High doses of IG have been demonstrated to inhibit the response to measles + varicella + rubella vaccine for a prolonged duration. q. In contrast with live-virus vaccine administration of IG has not been demonstrated to cause significant inhibition of the immune responses to inactivated vaccines and toxoid.

• Immunization in special clinical circumstances • Preterm infants • Prematurely born infants, including infants of low birth weight, should be immunized @ the usual chronologic age in most cases. • If an infant is still in the hospital @ 2 months of age, the immunization routinely scheduled at that age including DPT, H 1 b and IPV.

• Management of preterm infants born to HBs. Ag negative mom • In low birth weight less than 2 kg the sero conversion rate reported to be lower than rates in preterm immunized at a later age and in term infant immunized shortly after birth. • Hence, immunization in preterm infant with birth weight of less than 2 kg whose mothers are HBs. Ag negative should be delayed until just before hospital discharge if the infant weighs 2 kg or more or until approximately 2 months of age when immunization are given.

• Pre term infant with birth weight less than 2 kg whose mothers are HBs. Ag positive should receive hepatitis immune globulin within 12 hours of birth and concurrent hepatitis B vaccine at different site (and this dose should not be counted). • if the maternal HBs. Ag status is unknown, the vaccine should be given in accordance with recommendation for the infant of an HBs. Ag-positive mother.

• HIV Infection 1. MMR • Should be given to asymptomatic children and those who are symptomatic but are not severely immune compromised. • Why it should be given? • Because of reports of severe measles in symptomatic HIV children including fatalities in 40% of cases.

2. Varicella - should be considered for asymp or mildly symp with age-specific CD 4. T lymphocyte % of 25% or more. 3. Routinely recommended childhood vaccines, including DTab, IPV, Hep B, Hib according to the recommended schedule.

• 4. Annual influenza • 5. Pneumococcal vaccine based on the age • 6. BCG is contraindicated

• Asplenic Children Surgical Removal Congenital asplenia Functional asplenia i. e. SCD Why→↑ fulminant bactremia

• What type of vaccine? 1 Pneumococcal vaccine @ 2 years and older 2 Hib vaccine @ 2 m of age 3 Quadrivalent meningococcal vaccine @ 2 years of age and older

• Pneumococcal Disease • Children less than two years are at highest risk, especially 6 -11 months • 500, 000 cases of pneumococcal disease are estimated to occur every year in Canada • The number one cause of bacterial pneumonia and meningitis

• Pneumococcal Disease in Children • Estimated annual number of cases in children less than 2 years of age • • Meningitis: Bacteremia: Pneumonia: Otitis media: 60 1000 3000 200000

• Pneumococcal Conjugate Vaccine 97% effective in preventing bacteremia and meningitis in infants • Pneumonia • Clinical diagnosis: ↓ 11% • Infiltrate on x-ray: ↓ 33% • Consolidation “ 2. 5 cm : ↓ 73%

• Pneumococcal Conjugate Vaccine • Acute otitis media • • Any episode Any Pnc otitis Vaccine serotype Pnc & ruptured TM ↓ 6% ↓ 34% ↓ 57% ↓ 65% Pneumococcal carriage 40 -50% ↓ in vaccine serotypes 4 -050% ↑ in non-vaccine serotypes

• Pnc Conjugate Vaccine Use • NACI recommends routine immunization of all infants less than 2 years of age. Because attendance at group child care increases risk of pneumococcal disease, healthy children 24 -59 months of age should be vaccinated. • Vaccination of healthy children 24 -59 months of age not in group child care should be considered.

• • • Vaccination Does not Cause Autism Inflammatory bowel disease Asthma and atopic disorders SIDS Type 1 diabetes Multiple sclerosis Chronic fatigue syndrome AIDS, cancer, ADD, etc.

• MMR and Autism: 1 A large study of children with autism in England found that there was no association between the date at which MMR was given and the date when parents first became concerned about abnormal behavior in their child.

• MMR and Autism: 2 • The frequency of autism in USA appears to have increased in recent years. • This increase occurred long after MMR vaccine was introduced. • No increase in autism rates has been observed following the introduction of MMR vaccine in USA, Canada, Europe, or Japan.

• MMR and Autism: 3 • All evidence concerning MMR and autism has been reviewed independently by expert committees of the Institute of Medicine in the USA, the American Academy of Pediatrics, and CPS. • They agree that there is no scientific evidence to support theory that MMR causes autism or autistic spectrum disorders or inflammatory bowel disease.

• Vaccination and Asthma • A large International study analyzed immunization rates and rates of asthma and other allergic diseases from 91 centers in 38 countries in six and seven years old, and also in 99 centers in 41 countries in children 13 to 14 years old. There was no correlation between immunization rates and asthma/allergy rates.

• Vaccines and Immune Exhaustion • Infants estimated to have the capacity to respond to about 10, 000 different antigens at any one time. • Current vaccines much more highly purified than those in the past. • Even though infants now receive more vaccines than they did 30 years ago, total amount of proteins and polysaccharides is much lower today than it used to be.