8. Vaccine Preventable Childhood Diseases and Disease Eradication

• usually virus
• Neisseria meningitidiss - gram-negative diplococcus
• Haemophilus influenzae - gram-negative bacillus

respiratory route - crowding important

• establish infection in the throat
• rare, can spread to meninges via the bloodstream
• have capsules - prevent initial phagocytosis
• multiplication leads to inflammation of the meninges

• intense headache
• stiff neck
• vomiting
• for N. meningitidis purple-black skin lesions can occur

• gram stain of spinal fluid after centrifugation
• culture on appropriate media and biochemical tests to confirm
• latex agglutination
• PCR

with antibiotics early to be effective

• N. meningitidis:
• isolation of cases during epidemics
• screening for carriers
• treating contacts of cases
• vaccines

• H. influenzae:
• treatment of initial sore throat to prevent spread
• vaccine

• Corynebacterium diptheriae
• gram-positive bacillus

droplet infection

disease caused by a potent exotoxin - interferes with protein synthesis in cells

• swollen neck
• characteristic pseudomembrane

• growth on specialized medium
• culture and gram stain
• biochemical tests
• identifying toxin with reagent antibody
• PCR

passive immunization with antibody against toxin

toxoid vaccine - produces neutralizing antibodies against toxin

• Bordetella pertussis
• gram-negative coccobacillus

respiratory route

toxin mediated - disables cilia on the respiratory epithelium and kills the cell

• usually in young children
• starts like common cold
• spasm-like cough with "whoop"

• clinical
• culture with biochemical tests
• PCR

antibiotics

vaccines

• Clostridium tetani
• gram-positive bacillus
• anaerobic, endospore forming

soil

direct contact with soil or objects contaminated with soil

• caused by potent exotoxin made by bacteria that infect wound
• strict anaerobe, usually occurs in deep wounds
• host produces antibodies that neutralize toxin, but often not fast enough

• involuntary, prolonged contractions of muscles
• neonatal tetanus occurs when umbilical cord cut with soil contaminated instruments

clinical

passive immunization with antibodies that neutralize toxin

toxoid vaccine

• mumps virus
• ssRNA

respiratory

clinical

no curative treatment

vaccine

• infects salivary glands, causing enlargement
• other tissues can become involved
• immune response good, usually life-long protection

• skin eruption occurring as a result of a generalized infection throughout the body
• measles, rubella, chickenpox, smallpox

• measles virus
• ssRNA

• rubella virus
• ssRNA

• varicella-zoster virus
• dsDNA

• smallpox virus
• dsDNA

• respiratory route
• from skin to respiratory route also possible

• primary multiplication in the respiratory tract
• moves to lymph nodes and multiply
• goes systemic, multiplying
• host responds with both CMI and humoral immunity, lifelong protection

• rash
• respiratory symptoms
• conjunctivitis

• usually asymptomatic or mild
• rash, swelling of lymph nodes
• most dangerous to fetus in first trimester

• usually mild, characterized by vesicles
• becomes latent in nerve tissue, can reactivate later if immune system depressed causing shingles or zoster - infectious

fever and rash with nodules

clinical

no curative treatments

live attenuated vaccines

• "Target Zero" strategy
• ring immunization - cases are identified and their contacts are immunized

• humans are the only reservoir
• infection always result in characteristic signs, no subclinical/latent carriers
• antibodies are protective against infection

demonstrates potential of public health interventions for preventing disease in the population, as opposed to just treating individual

• poliovirus
• ssRNA virus

fecal-oral route

• virus multiplies in intestine
• rare, spreads to central nervous system in the blood
• multiplies in neurons
• leads to paralysis of the areas of infected neurons
• humoral immune response confers lifelong immunity

• majority asymptomatic
• more likely to be symptomatic when acquired later in life
• some influenza-like symptoms, paralysis

• clinical
• isolation
• antibody detection
• PCR

no curative treatment, only supportive

• sabin: live-attenuated vaccine
• given orally
• stimulates IgA
• requires boosters
• can revert to wild type and cause disease in immunocompromised

• Salk: killed/inactivated virus vaccine
• injected
• only prevents disease, not infection
• no boosters

• Dracunculus medinensis
• nematode (roundworm)

fecal-oral route

• humans drink unfiltered water with copepods and larvae
• larvae penetrate host's stomach and intestinal wall - mature and reproduce
• migrate to surface of skin, causing blister, discharge larvae
• larvae released into water
• consumed by copepod

• worm causes intense pain as migrates to extremities
• causes swelling, then blister progressing into lesion

• no medicine
• when worm emerges from skin, slowly wrapped around a stick to extract

• do not drink contaminated water
• filter contaminated water
• stop people with emerging worms from entering drinking water sources
• treat water with larvicides to kill copepods
• develop new, clean water sources