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
activities with no risk of HIV transmission
- shaking hands
- hugs
- kissing
- sharing or eating with same utensil
- sharing towels, a phone, napkin, or using the same toilet
biological basis of HIV transmission
- HIV is an obligatory intracellular parasite and cannot “live” outside the host
drug therapy
- one negative aspect of AZT is its toxic side effects on normal cellular DNA replication, that can cause anemia
HIV testing and risk assessment
- the immune system may take up to 6 months to produce antibody to the virus
reporting rules
- U.S. states require medical personnel to report anyone with a positive HIV test to the state health department
universal precautions
- gloves, masks, for anyone exposed to blood or bodily fluid
- patient to caregiver transmission of HIV is now extremely rare
vaccine development
- efforts to make a HIV vaccine is difficult because the virus has a high mutation rate, the virus lies dormant in some cells, and the virus can spread through cell to cell contact
animal model possibilities
- the hybrid virus can replicate and cause AIDS in monkeys.
- this may help in testing vaccine candidates
biomedical ethics
- in terms of HIV/AIDS the goal is better prevention through vaccines and treatment of infected individuals
Is the swine flu (H1N1) contagious? If so, how is it transmitted?
- highly contagious
- spreads when people cough or sneeze; anyone who comes in contact with a surface that someone infected with the H1N1 virus has recently touched can also contract the virus
What type of transmission is this called?
person-to-person
person-to-fomite
Can a person acquire swine flu from eating food particles derived from pigs such as ham or bacon?
NO
What are the symptoms of the flu?
- fever
- general weakness
- headaches
- severe aches and pains in muscles and joints, especially around the eyes
- digestive problems such as stomach ache or diarrhea can also be an issue
- dry cough
- runny nose
- sore throat
- watery eyes
How long does the flu last in a person?
usually 1-3 days but some symptoms may continue after the fever has left
-in a weakened immune system it can last up to 2 weeks
If left untreated, what more serious complications can occur?
pneumonia and respiratory failure
How do flu vaccines work?
after 2 weeks, the vaccine builds up antibodies
Does the flu vaccine work right away?
- no, it takes 2 weeks after vaccination for antibodies to develop in the body and provide protection against influenza
- that’s why it is better to get vaccinated early in the fall before the flu season gets under way
If viral load is high what happens to CD4 count? What happens to CD4 count when viral load is low?
high viral load = low CD4
low viral load = high CD4
Ebola
- severe and often fatal
- Western Africa
- blood clots
- hemorrhagic fever
Zica Virus
- spread to people primarily through the bite of an infected aedes mosquitos
- during pregnancy, it can cause severe birth defects such as microcephaly
PEP
Post Exposure Prophylaxis
- can be prescribed for people who have potentially been exposed to HIV
- important for people who have been sexually assaulted or who have been exposed to blood through a needle injury or other accident at work
- It’s an antiretroviral drug treatment that prevents HIV from becoming established
- month long course of two or three different types of antiretroviral drugs
PrEP
- Truvada
- prescribed to those who are at greater risk to HIV
- reduces the risk of HIV infection in adults who are HIV-negative and at high risk of getting HIV infection
- PrEp does not always prevent HIV so other prevention such as condoms should always be used
- when Truvada is used to treat HIV infection its often used with other HIV medicines
ELIZA
Enzyme-Linked Immunosorbent Assay
- detects the presence of an antibody that was formed from exposure to the virus
- performing an ELISA involves at least one antibody with specificity for a particular antigen
- assay - to examine or analyze
Western Blot
- also an antibody detection procedure
- done as a secondary test to ELISA because it is more sensitive and confirms a positive ELISA result
- viral proteins are separated and immobilized
- the cells that are infected with HIV will open and their proteins are collected
- more costly, more time needed
- less likely to produce false positives
HPV
Human Papillomavirus
- common warts, planter warts, anogenital warts, anogenital cancers, pre-cancers, oral lesions
- 2 vaccines are marketed as of 2014 - Gardisil and Cervarix; both protect against HPV16 and HPV18 that cause 90% of genital warts, 70% of cervical cancers, 80% of anal cancers, 60% of vaginal cancers, 40% of vulva cancers
- vaccine is covered by insurance
- $135/dose and 3 doses over 6 months is suggested
- both males and females benefit from vaccine
Mode of transmission for HPV?
direct - person to person
Mode of transmission for Lyme Disease?
vector-borne
Difference between common cold and influenza
Cold Flu symptoms: gradual v. abrupt fever: rare v. usual aches: slight v. usual chills: uncommon v. fairly common fatigue, weakness: sometimes v. usual sneezing: common v. sometimes chest discomfort, cough: mild to moderate v. common stuffy nose: common v. sometimes sore throat: common v. sometimes headache: rare v. common
Can measles be fatal?
Yes
3 types of diabetes?
Type I, Type II, Gestational
If immune system is weakened, is one more susceptible to Tuberculosis?
Yes
How effective is hand washing in contracting the common cold?
Very effective
Fomite transmission
an inanimate object that may be infected with infectious agents
vehicle borne transmission
indirect transmission of an infectious agent that occurs when a vehicle (or fomite) touches a person’s body or is ingested
Primary, secondary, tertiary prevention
Primary Prevention - trying to prevent yourself from getting a disease. Secondary Prevention - trying to detect a disease early and prevent it from getting worse. Tertiary Prevention - trying to improve your quality of life and reduce the symptoms of a disease you already have.
Hepatitis B
blood borne virus that are sexually transmitted or injection drug use
- a high proportion of adults are at risk for HBV
- people who have HIV and HBV can have serious medical complications
- to prevent HBV infection in HIV infested people, a Hep B vaccine is recommended for susceptible patients with HIV/AIDS
Hepatitis C
- about 1/4 of HIV infected people in the US are infected with Hep C
- HCV is a blood borne virus transmitted through direct contact with the blood of an infected person
- coinfection with HIV and HCV is common 50-90% among HIV infected injection drug users
- HCV is one of the most important causes of chronic liver disease in the US and HCV infection progresses more rapidly to liver damage in HIV-infected people
- HCV infection may also impact the course and management that all HIV infected people be screen for HCV infection
Bacteria
- prokaryotic cells
- they do NOT contain a nucleus
- the have a cell wall and cell membrane
- their genetic material simply floats around in the cytoplasm
- many have flagella for locomotion
Viruses
- without a host cell, viruses cannot carry out their life sustaining function or reproduce
- they cannot synthesize proteins because they lack ribosomes
- they must use the ribosomes of their host cells
- viruses cannot generate or store energy because they lack mitochondria
- they have to derive their energy from the host cell
Treat of HIV infected individuals
- antiviral drugs help block virus replication
- antiretroviral drugs destroy or inhibits the replication of retroviruses (reverse transcriptase- produces DNA from RNA)
- Biomedical research has developed a number of drugs that interfere with HIV replication
- research is working on ways to restore the immune system and improve treatment of opportunistic infections
Restoring Immune System
- research is looking for blood cell growth factors that will help restore the immune cells destroyed by HIV infection
- IL-2 (interleukin 2) is required by T helper and T killer cells and could be helpful in regenerating the immune system
- IL-2 produces severe side effects that require administration in a hospital as well as being very expensive
Animal Model Possibilities
- lacking an animal model limits research in developing a vaccine
- a promising possibility is a hybrid simian-human immunodeficiency virus (SHIV) made by recombinant technology. The hybrid virus can replicate and cause AIDS in monkeys. This is helping in testing vaccine candidates
- special mice with defective immune systems (SCID - severe combined immunodeficiency) lack functional cellular immunity. Transplanting human immune cells into these mice allows HIV infection for research study.
