Resurging and Emerging Infectious Diseases

Question 1

Emerging Infectious Disease

Answer 1

Disease that has appeared in population for first time, or may have existed previously but is rapidly increasing in incidence or geographic range
- Usually vector-borne (mosquito) or zoonotic (animals) which then become transmitted to humans

Question 2

Resurging Infectious Disease

Answer 2

A well established human disease that shows a new upward trend in incidence or prevalence after initially dropping to levels where it is deemed to no longer be a public health concern. Often Vaccine-preventable diseases.

Question 3

Why do diseases Emerge and Resurge?

Answer 3

• Agent Factors: Microbial adaptation evolution leading to changes in pathogenicity, Development of antibiotic resistance, resistance of vectors to pesticides and contorl measures
• Environmental Factors: Climate change leading to expansion in distribution, economic development and land use, technology and industry
• Human Factors: Biological (decreased overall immune competence due to very sanitary conditions), Behavioural (increased travel and migration)

Question 4

Measles:
Epidemiology
Clinical Presentations
Diagnosis
Management

Answer 4

• Virus
• Epidemiology: Worldwide distribution, vaccine preventable, increasing incidence in developed countries!
• Clinical Presentations: Prodromal illness (fever, malaise) then will develop maculopopular rash starting on face then spreading to body!! It’s like pouring can of red paint on head.. starts on face then goes to rest of body. Also KOPLIK SPOTS.. which are blue-grey specs on red base of buccal mucosa!! ONLY MEASLES HAS THIS
• Transmission: Droplet and airborne route!
• Diagnosis: Look for koplik spots! IgM in blood, PCR from any body fluid
• Management: Mostly supportive… Vitamin A through IV can reduce severity and duration

Question 5

Mumps:
Epidemiology
Clinical Presentations
Diagnosis
Management

Answer 5

• ss-RNA Virus
• Epidemoiology: Worldwide distribution, vaccine preventable, 99% decline in incidence
• Clinical Presentations: Non specifice prodrom (low fever, malaise). UNILATERAL earache, tenderness, progressing to unilateral swelling!! Extrasalivary manifestations are rare.. but can occur… epididymoorchitis… is scary! Testes can swell to 2x to 3x bigger than normal..
• Transmission: Direct contact or droplet, NOT AIRBORNE
• Diagnosis: Clinical diagnosis, IgG, PCR from buccal swab
• Managment: Supportive! Perhaps isolate for 5 days

Question 6

Pertussis (whooping cough):
Epidemiology
Clinical Presentations
Diagnosis
Management

Answer 6

• Bacterial Infection!.. Bordtella Pertussis!
• Epidemoiology: Before vaccine attacked ages 1-10, but now with vaccines we primarily see it in infants <1 year old.
• Clinical Presentations: 3 stages!
  1. Catarrhal Stage: 1-2 weeks, URTI like illness… cold.. flu…
  2. Paroxysmal Stage: 1-6 weeks, Spasms of uncontrollable coughing, have “whoop” at end of paroxysms
  3. Convalescent Stage: 2-3 weeks, gradual recovery, cough lessens, susceptible to other infections!!
• Transmission: Direct contact or large droplet! Most infectious in Catarrhal and beginning of Paroxysmal
• Diagnosis: Bacterial culture from respiratory secretions, PCR, Serology only helpful late in disease
• Managment: Macrolide antibiotics (clamifrozycin, amithrozycin) IF diagnosed within 3 weeks. Supportive care is important!

Question 7

**** ON TEST***Gain insights into the role of vaccinations in the control of vaccine preventable diseases (herd immunity)

Answer 7

• Induction of immune response by active means!
  
  • Enough individuals in population are immune to a disease through vaccination and natural immunity that spread of the disease from person to person is unlikely or impossible. Provides protection for pregnant women, infants, immunocompromised (those who cannot be safely vaccinated)
  • Proportion of population needed to be immunized to achieve herd immunity is different for each disease… depends on how contagious disease is and how effective vaccine is.
  • An individual protected through herd immunity is not necessarily immunologically protected from a disease! Ex.. those not vaccinated!

Question 8

Summarize Zika Virus

Answer 8

Zika Virus: First isolated in Uganda in 1947. Transmitted by two mosquitos.. Primary vector is Aedes Aegypti… and then Aedes Albopictus! 2 Strains… African and Asian (african is old world). Usually Asymptomatic

Question 9

Summarize Ebola Virus

Answer 9

Ebola: Virus, Caused by Zaire strain.. wildtype strain! Found in Congo in 1976! Diarrhea, bleeding out ears and eyes! Then systemic shock develops and kills them. Transmitted by contact with infected bodily fluids!

Question 10

Vaccine Types

• Live-attenuated
• Inactivated/killed
• Component/subunit
• Toxoid

Answer 10

• Live-attenuated: Organism is alive and replicates
  
  • Inactivated/Killed: Organism is killed by chemical or heat and unable to replicate
  • Component/subunit: Contains specific antigens! Which can stimulate an immune response
  • Toxoid: Contains detoxified version of a bacterial toxin which would normally cause disease.