Final Exam Flashcards
What is HIV?
- a human immunodeficiency virus that causes AIDS
- people may not know they have it and may be infect/affected for many years
- damages the body’s immune system
How are you at risk for HIV?
- have had sex with a man or woman who has had other partners
- HIV semen, blood, or vaginal fluids (penis, vagina, rectum, or mouth)
- have shared needles to inject drugs or had sex with someone who has
- blood with HIV is left in needle or syringe (injection of drugs, vitamins, steroids, tattoos, or piercings)
- have shared needles for any reason or had sex with someone who has
Can I get AIDS from sharing a cup or shaking hands with someone who has HIV or AIDS?
No. Sharing cups or utensils has never been shown to transmit HIV.
Epidemic/Epidemiology
the study of the spread of disease within a population is epidemiology
Transmission Rate
- 2 factors affect transmission rate:
1. inherent efficiency
2. encounter rate
inherent efficiency
ease with which the agent infects a susceptible host
encounter rate
between infected and uninfected persons
acute infection
acute infections show symptoms very rapidly after infection occurs and once the immune response curtails the agent, the symptoms recede
chronic infection
the infected person responds to the agent immunologically but does not clear the virus entirely
- HIV/AIDS is a chronic infection
Koch’s Postulates
- germ theory of disease
- Robert Koch proposed 4 steps used to prove an infectious agent causes a disease
Robert Koch’s 4 steps to prove an infectious agent is a disease.
- the organism is always in the person with the disease
- the organism can be isolated and grown in pure culture
- the cultured organism will produce the disease if given to a susceptible host
- the organism can be re-isolated from the newly infected host
virus
- all viruses are obligate intracellular parasites:
- viruses cannot replicate outside a host cell
- all viruses contain nucleic acid (RNA or DNA) encased in a protein coat (capsid)
- some viruses contain a second coating derived from a host cell membrane containing lipids and glycoprotein called the envelope
non-enveloped virus
e. g. poliovirus
- only contains protein coating with genetic material inside
enveloped virus
e. g. HIV
- contains viral envelope protein (glycoprotein), membrane, protein coat, then genetic material
portals of entry
- oral
- respiratory
- genital/urinary
- digestive
- breaks in skin: cuts, IV needle, bites, abrasions
- rectum
- occipital
typical virus infectious cycle
- attachment or binding: (adsorption) between virus and host cell. receptor is present.
- penetration: entry of genetic material of virus into cytoplasm of the host cell
- expression of the viral genetic material including transcription and translation of viral coded proteins
- replication of viral genetic material
- assembly of virus particles
- maturation of viral particles
- release of viral particles
How should we treat viral infections?
antibiotics interfere with bacteria and fungi replication, but are not helpful in fighting viral infections
What is a retrovirus?
a virus containing RNA and a unique enzyme, reverse transcriptase, that converts RNA into DNA.
Retrovirus life cycle
attachment: HIV hp120 attaches to CD4 on T-helper cells and then binds a co-receptor CCR5 or CRCX
- the t-helper lymphocytes are the primary target of HIV
treatment for HIV
- antiviral drugs are designed to block a specific event in virus replication
- finding drugs that interfere with the virus but are not toxic to the host is challenging
- it does help reduce the speed of progression delays onset of ARC/AIDS and allows persons to live a better quality of life longer
initial symptoms of HIV
- first few months patients may experience symptoms similar to the flu or mononucleosis
- swollen lymph glands
- lymphadenopathy (whole lymph system)
opportunistic infections
- early immune failure
- candida
- thrush
- shingles
- herpes varicella-zoster
- Kaposi’s sarcoma
candida
- a yeast infection of the mouth, mucosal areas of body
- thrush is candida infection in the mouth
- absent treatment may progress to esophagitis and into ear canal
shingles
caused by chickenpox virus, herpes varicella-zoster
- acyclovir is a drug useful in treating shingles
Kaposi’s sarcoma
the product of human herpes virus 8 (HHV8) or Kaposi’s sarcoma herpesvirus (KSHV)
clinical management
during the course of HIV progression, patients must be monitored for virus load and CD4 count
- normal healthy individuals have 1000 CD4 cells per ml of blood
- <200 CD4 cells/ml defines AIDS
- A CD4 countless than 400 indicates immune system damage and early immune failure
Modes of Transmission of HIV
- epidemiological data points to 3 modes of transmission:
- birth: perinatal transmission mother to child
- blood: HIV infected fluid/cells enter bloodstream of HIV-person
- Sex: intimate sexual contact with HIV+ person