Addendum to Overview of Infectious Process Flashcards
Infectious disease stages
Incubation - period from initial exposure to onset of the first symptoms; could last from hours to years
Prodromal - the occurrence of initial symptoms are often very mild with feelings of discomfort and tiredness. In this phase, the numbers of the infectious agents start increasing and the immune system starts reacting to them. It is characterized by early symptoms that might indicate the start of a disease before more specific symptoms.
Invasion (acute period?) - invasion affects other body tissues; symptoms from pathogens and from immune response. Acute period - active replication or multiplication of the pathogen and its numbers peak exponentially, quite often in a very short period of time. Symptoms are very pronounced.
Convalescence - recovery occurs and symptoms decline, or the disease is fatal, or has a period of latency
Colonization: Means of transmission
Horizontal: droplet, physical (STIs, skin infections), aerosolized (SARS, TB, smallpox)
Vertical: placenta to fetus, mother to infant in birth canal or in breast milk (HIV, Zika, Congenital Rubella)
Microbiome: breach in first line of defense, skin or mucous membranes
AIDS susceptible to
life-threatening infections and cancer
AIDS transmission
Blood borne pathogen: body fluids
Blood or blood products, IV drugs, sex, maternal-child transmission
Two types of viruses that cause AIDS
HIV-1, HIV-2
Pathogenesis of HIV/AIDS
- what kind of virus?
- stores genetic material on?
- carries what enzyme
May remain dormant and no problems develop
Stores genetic material on two copies of RNA rather than the usual dsDNA
Carries an enzyme: reverse transcriptase that creates a dsDNA version of the virus (this is why we have drugs to inhibit reverse transcriptase for HIV)
Integrase inserts new DNA into the infected cell’s genetic material
Targets of HIV
Mainly CD4
- reverse ratio of CD4 to CD8
- dendritic cells
- macrophages
- CD-8 T cells
- Thymic cells
- NK Cells
- Neural monocytes
HIV Virus enters lymphoid areas of mucosa
Dendritic cells and T cells spread infection to other organs
CD4 count normally
800-1000
HIV
Decrease in ______ cells
Decrease in the _______ ratio to what
CD4 cells decrease
CD4/CD8 ratio from 1.9 to as low as zero
Clinical manifestations:
Serologically negative (incubation period)
When is the window period?
Virus may be detectable when?
Early symptoms are?
Window period: b/w infection and appearance of antibody
Usually 4-7 weeks, but could be 6-14 months
Virus may be detectable within weeks after infection
Early s/s are non-specific: fatigue, h/a, muscles aches, fever
Serologically positive but asymptomatic = Early stages of HIV
- may be as long as 10 years in some untreated individuals
- viral load increases
- number of CD4 cells decreases
Diagnosis of AIDS
- seropositive (have antibodies)
- opportunistic or atypical infections and cancers: Kaposi sarcoma, toxoplasmosis, cytomegalovirus, pneumocystis jirovecci (yeast-like fungus)
- Indications of chronic, debilitating disease: wasting
- CD4 cells at or below 200cells/uL
Treatment of HIV
Antiretroviral therapy (ART)
- three or more drugs d/t increased resistance
- usually 2/3 drugs target reverse transcriptase (Inhibits reverse transcriptase) and one is from a different class of drugs
- does NOT CURE, but slows progression
- treat opportunistic infections
- no vaccine
- prevention consists of avoiding contact with the virus
*sometimes people appear to be in remission
Presence of passive maternal antibody limits testing of HIV antibodies in infants up to ________
What is particularly vulnerable?
Tx?
18 months
CNS - developmental delays, impaired brain growth or microcephaly, motor deficits
Tx: preserve immune function, aggressive tx of opportunistic infections, relief of symptoms, antiretroviral therapy
