Micro Final Viral Diseases

What is the structure of influenza?

What is the structure of influenza?

• Protein layer

• Lipid bilayer

  • Hemagglutinin (HA)

  • Neuraminidase (NA)

• M2 ion channel

• Single stranded RNA

  • RNA in 8 pieces

Why do we need the flu shot every year?

• Antigenic drift

  • Repeated mutations cause gradual change in HA and NA

• Antigenic shift

  • Sudden shift is caused when the virus acquires genome segments from another influenza virus by recombination

What is the causative organism of influenza?

Influenza A,B, and C viruses

• Enveloped, ssRNA in 8 segments

What is the mode of transmission of influenza?

• Droplet contact - coughs and sneezes

• Direct contact - handshake

• Indirect contact - fomite

What is the incubation period of influenza?

1 to 2 days

What is the pathogenesis of influenza?

• Infection of respiratory epithelium causes lysis

• Secondary infections results from damage to the mucociliary escalators

What are the virulence factors of influenza?

Hemagglutinin - for attachment, binds to sialic acid Receptors

Neuraminidase - for release - removes sialic acid from cell surface

What are the symptoms of Influenza?

Fever, headache, sore throat, cough, runny nose, muscle aches, (myalgia)

What is the prevention of influenza?

Killed infected vaccine or inhaled live attenuated Caine taken annually

• Handwashing

What are the distinctive features of influenza?

Antigens can shift or drift

What is the causative organism of poliomyelitis?

Poliovirus, ssRNA non-enveloped

What is the mode of transmission of poliomyelitis?

Fecal oral , vehicle

What is the virulence factors of poliomyelitis?

Attachment mechanisms

What are the symptoms of poliomyelitis?

• initially: sore throat and nausea

• Viremia may occur, if persistant, virus can enter the CNS

• Destruction of motor cells and paralysis occurs in 1% of cases

What is the prevention of poliomyelitis?

• Live attenuated (OPV) Sabin vaccine

• Inactivated vaccine (IPV) Salk vaccine preferred in US (not likely to revert)

What is the causative organism of rabies?

• Rabies lyssaviruss formerly rabies virus

• ssRNA enveloped

What is the transmission of rabies?

Parenteral (bite trauma), droplet contact

What are the virulence factors of rabies?

Envelope glycoprotein enables to spread to CNS

What are the symptoms of rabies?

• Initial stages include hydrophobia

• Furious rabies: Animals are restless, then highly excitable

• Paralytic rabies: Animals seem unaware of surroundings

What is the prevention of rabies?

HDCV - Human diploid cell rabies vaccine - an inactivated vaccine

What is the treatment of rabies?

Post-exposure antiserum and active immunization

What is the causative agent of smallpox?

Various virus, enveloped dsDNA virus

What is the mode of transmission of small pox?

Droplet contact, indirect contact

What is the virulence factor of smallpox?

Ability to dampen and avoid immune response

What are the signs and symptoms of smallpox?

Fever, prostration, rash, toxemia, and shock

What is the prevention of small pox?

Live virus vaccine - vaccinia virus

What is the treatment of small pox?

Immunoglobulin - passive immunity

What is the causative organism of measles (Rubeola)?

Measles morbillivirus formerly known as MEasles virus ssRNA enveloped

What is the mode of transmission of measles?

Droplet contact via respiratory portal

What are the signs and symptoms of Measles?

Maculopapular rash

Koplick spots in the mouth

What are the virulence factors of measles?

Syncytium formation, ability to suppress cell-mediated immunity

What is the prevention for measles?

Live attenuated vaccine (MMR)

Who is Carlos Findlay?

A Cuban doctor proposes mosquito transmission rather than human contact for yellow fever

Who is Walter Reed

Him and a team of doctors proved the mosquit transmission hypothesis

• Let lab raised mosquitos feed on yellow fever patients

• Then on members of the commission

Disease eliminated from Havana through mosquito control

• Later use to control mosquitos in the Panama Canal Zone enabling its construction

What are the complications of measles?

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

What is the causative organism of yellow fever?

Yellow fever virus, +ve ssRNA enveloped

What is the transmission of yellow fever?

Bite of the Aedes aegypti mosquito

What is the transmission 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

What are the virulence factors of yellow fever?

• Disruption of blood clotting factors

• Death may occur from cytokine storm and shock

What is the treatment of yellow fever?

Supportive care

What is the prevention of yellow fever?

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

• Live attenuated vaccine

What is malaria?

Ancient disease, found in early Chinese, Hindu writings

• Malaria means “bad air”

• 1902 Ronald Ross - Nobel Prize for demonstrating life cycle of protozoan causing malaria

• Most common serious infectious disease worldwide

For what disease did WHO program for global elimination?

Malaria

• Initially successful - 52 nations participated

• Mosquito vectors developed resistance

• IN 1976, WHO acknowledged failure

How many people are infected annually with malaria?

Over 200 million

• More than 450,000 deaths per year

What is the causative organism of malaria?

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

What is the mode of transmission of malaria?

• Biological vector - bite of mosquito

• Humans are the primary host

What are the symptoms and signs of malaria?

• Cyclic symptoms correlating with the parasite’s life cycle

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

• Other symptoms - anemia, fatigue, and jaundice

What are the virulence factors of malaria?

• Multiple antigenic types to evade the immune response

• Ability to scavenge glucose

• Cyto-adherence

• Invasion of RBCs

What is the prevention of malaria?

• Mosquito control

• Use of bed nets

• No vaccine available

• Prophylactic anti-protozoal agent

What is the treatment of malaria?

Artemisinin - based Combination Treatment (ACT)