Module 4 Flashcards
(29 cards)
Blood borne pathogens of greatest concern (3)
- HBV (Hepatitis B virus)
- HCV (Hepatitis C virus)
- HIV/AIDS
Risk of infection after poked with a needle/ no gloves
- HIV (AIDS): 0.3%
- HCV: 3.0%
- HBV: 30.0%
Gloves reduce risk by 50% as blood wiped off outside of glove as needle passes through it
Hepatitis
-inflammation of the liver
-symptoms: jaundice, dark urine, pale feces
-causes: viruses
(Hep A, B, C, D, E) bacteria, parasites, alcohol, chemicals
Hepatitis A (HAV)
- Previously called: infectious hepatitis, short incubation hepatitis
- Causative agent: HAV; naked
Hepatitis A entry into host and replication process
HAV-contaminated food or H2O –> ingested by new host replicates in mouth, intestine, and liver –> excreted via bile duct into intestinal tract –> HAV in feces
Diagnosis of HAV
Most hosts get typical hepatitis symptoms usually no permanent liver damage; don’t usually die
No chronic carriers
Test blood for anti-HAV antibodies
How is HAV transmitted and Prevented
Transmitted: via food or H20 contaminated with feces or saliva
Prevention: keep stool and drool out of food, hepatitis A vaccine for travellers going to areas of poor sanitation and for identified contacts of people with hepatitis A
Hepatitis B (HBV)
Previously called: serum hepatitis (but found in other body fluids too) or long incubation hepatitis
Causative agent: HBV; enveloped
HBV entry into host and replication process
HBV –> blood or mucous membrane –> replicates in liver –> HBV in blood, semen, vaginal secretions, CSF, …
HBV infection
- Most hosts are a symptomatic
- some get typical hepatitis symptoms, a few get fulminant form; rapid, severe, can be fatal
Chronic carriers: yes; 5-10% (even if asymptomatic)(meaning no disease symptoms)
Implication: serve as reservoir for HBV; body fluids infectious of several years- great incidence of hepatic cancer down the road
Diagnosis of HBV
-test blood for serological markers
HBsAg used to initially diagnose HBV (surface Ag)
Anti-HBs presence indicates successful immunization (surface Ab) or patient recovering from HBV infection
How HBV is transmitted and prevented
Transmitted: usually via blood (most infectious source; minute amount will do it)
Anything leading to blood-blood or blood-mucous membrane contact
(Ex. Sharing needles, blood spill on broken skin, tattooing, bloody sex, mom can transmit to fetus
Other infective fluids: semen, vaginal secretions, CSF, breast milk, saliva
(Feces not affected when in acute phase and in chronic carrier phase as with HAV)
Prevention: routine practice (assume every patient is infectious)
HBV vaccine
HBIG (immunoglobulin) if exposure to infectious material
Passive immunity
Potential risk situations at work of HBV
- anything where blood-blood or blood-mucous membrane contact
- HBV can survive for 1 week outside body. Spilled/dried fluids can be a source of infection.
- Keep work areas clean and dry
Hepatitis C virus (HCV)
Hepatitis C accounts for approx. 20% of al cases of acute hepatitis. MOST cases of hepatitis C are now associated with intravenous drug abuse.
Transmission and prevention of HCV
Transmission: via blood, less likely by other means- poor sexual transmission
Prevention: routine practice
Hepatitis B vaccine does not prevent against HCV. NO vaccine available.
Diagnosis of HCV
Chronic carriers: common; high risk of cirrhosis or liver cancer down the road
Treatment: interferon and/or combination of new drugs- not suitable for all patients
Risk of HCV to Health care workers
Not well defined
-most cases due to needle sticks or sharps injuries
HIV/AIDS viral replication
Causative agent: HIV; enveloped
- attachment to susceptible host
- go 120 (virus) to CD4 receptor site (helper T lymphocytes)/brain cells
- fusion to host cell membrane
- penetration
- reverse transcription (viral RNA–>viral DNA)
- incorporation of viral DNA into host cell DNA
- dormant period (variable); person infected but no symptoms
- replication of viral parts
- assembly of viral parts at host cell membrane and release–> off to infect new host cells
Effect of HIV on host cells
Kills helper T lymphocytes; when number is significantly reduced, get clinical symptoms of AIDS
Diagnosis of HIV/AIDS
-testing for HIV antigens is not routine
A. Do a screen test for anti-HIV antibodies problems:
- takes 4-12 weeks or longer after infection for anti-HIV Ab to appear “negative window”… person is infection, but test is negative
- can get false positives
B. If screen test is positive, do Western Blot to confirm
Progression of HIV infection
Contact –>
primary infection (1 month) -flu like symptoms or no symptoms, HIV test may be negative -->
Latent period (2 years) -slow destruction of CD4 cells, HIV test positive -->
Clinical AIDS
- variety of infections:
- cancers (kaposi’s sarcoma)
- protozoal: cryptosporidium
- fungal: candida oral thrush
- viral: shingles
- CD4 count < 200
- ultimately, death
Transmission and prevention of HIV/AIDS
Transmission: blood is most infectious fluid (but not as infectious as of HBV)
Other fluids: semen vaginal secretions, breast milk; virus must are contact with blood or mucous membrane of host
Ex. Sex, needle sharing, mom-baby, needle sticks, blood splash on mucous membrane or broke skin
NOT transmitted through routine kissing, touching
Prevention: routine practice
Treatment of HIV/AIDS
ZDV- slows viral replication and prolongs latent period, but does not kill virus and does not make new CD4 cells immune to attach
May be given in combination with other antiviral drugs.
HAART protocol.
No vaccine.
Risks of HIV to Health care workers
-accidental needle sticks or sharp injuries
-blood splash
-handling bloody equipment or clothing
(Risk of infection after exposure is low)
