Major Diseases

Influenza structure

Protein Layer

Lipid bilayer

M2 Ion Channel

Single Stranded RNA

Lipid bilayer

hemagglutinin (HA)

neuraminidase (NA)

Hemagglutinin (HA)

Protein on the surface of influenza virus that binds to sialic acid receptors

Neuraminidase (NA)

Protein on the surface of influenza virus that removes sialic acid from cell surface

M2 Ion Channel

Protein channel on the surface of influenza virus

Single-stranded RNA in influenza

Genetic material of influenza virus, divided into 8 pieces

Antigenic drift

Gradual change in hemagglutinin (HA) and neuraminidase (NA) due to repeated mutations

Antigenic shift

Sudden change in influenza virus caused by acquiring genome segments from another influenza virus

Causative agents of influenza

Influenza A, B, and C viruses

Transmission of influenza

Droplet contact, direct contact, or indirect contact

Influenza incubation

Period of 1-2 days between exposure to virus and onset of symptoms

Influenza pathogenesis

Infection of respiratory epithelium leading to lysis and damage to the mucociliary escalator

Secondary infections results from damage to the mucociliary escalator

Influenza virulence

Attach to sialic acid receptors (HA) and remove sialic acid from cell surface (NA)

Symptoms of influenza

Fever, headache, sore throat, cough, runny nose

Prevention of influenza

Flu vaccine and handwashing

Distinctive features of influenza

Ability of influenza virus antigens to shift or drift

Causative agent of polio

Poliovirus, a non-enveloped single-stranded RNA virus

Transmission of polio

Fecal-oral route or contaminated vehicles

Virulence of polio

Attachment mechanisms

Prevention of polio

Live attenuated (OPV) Sabin vaccine

Inactivated polio Salk vaccine

Causative agent of rabies

Rabies lyssavirus, an enveloped single-stranded RNA virus

Transmission of rabies

Bite trauma or droplet contact

Virulence of rabies

Envelope glycoprotein enables to spread to CNS

Symptoms of rabies

Initial symptoms of hydrophobia, followed by furious or paralytic rabies

Prevention and treatment of rabies

HDCV vaccine, post-exposure serum treatment and active immunization

Causative agent of smallpox

Variola virus, an enveloped double-stranded DNA virus

Transmission of smallpox

Spread of variola virus through droplet contact or indirect contact

Virulence of smallpox

Dampen and avoid immune response

Prevention and treatment of smallpox

Live virus vaccine (vaccinia virus), immunoglobulin treatment

Causative agent of measles

Measles morbillivirus, an enveloped single-stranded RNA virus

Transmission of measles

Droplet respiratory portal

Symptoms of measles

Maculopapular rash, Koplick spots in the mouth

Virulence of measles

Form syncytium and suppress cell-mediated immunity

Prevention of measles

MMR vaccine

Complications of measles

Diarrhea (8%), otitis media (7%), pneumonia (6%) and leading cause of death in adults - acute encephalitis (0.1%)

What did Carlos Findlay and Walter Reed do?

Carlos Findlay - hypothesized that yellow fever spread through mosquito bites

Walter Reed - proved the hypothesis by letting mosquitos feed on healthy people after feeding on yellow fever patients

Causative agent of yellow fever

Yellow fever virus, a positive single-stranded RNA virus

Transmission of yellow fever

Aedes aegypti mosquito bites

Symptoms of yellow fever

Most cases - mild infection - fever, headache, chills, back pain, fatigue, loss of appetite, muscle pain, nausea, and vomiting

15% of cases recurring fever, jaundice, bleeding from mouth and eyes, black vomit

Virulence of yellow fever

Disruption of blood clotting factors

Death may occur form cytokine storm and shock

Prevention of yellow fever

Repellant, proper clothing, avoid being outside at peak biting times

Live attenuated vaccine

Treatment of yellow fever

Supportive care

Ronald Ross

Won a Nobel Prize for demonstrating life cycle of protozoan causing malaria

Causative agent of malaria

Plasmodium falciparum, P. vivax, P. ovale, P. malariae, P. knowlesi

Transmission of malaria

Biological vector - bite of mosquito

Humans are the primary host

Symptoms of malaria

Cyclic symptoms correlating with the parasite's life cycle

Fever, chills, sweating every 48 to 72 hours as red blood cells lyse - combination of symptoms called a paroxysm

Other symptoms - anemia, fatigue, and jaundice

Virulence factors of malaria

Multiple antigenic types to evade the immune response

Ability to scavenge glucose

Cyto-adherence

Invasion of RBCs

Prevention of malaria

Mosquito control, bed nets, prophylactic antiprotozoal agents

Treatments of malaria

Artemisinin-based combination therapy (ACT)