Lecture 16: Sexually Transmitted Disease 2 Flashcards
How are STI’s spread?
Person -> Person
- Sex
- Oral-gen
- I.V drugs
- Congenital transmission
Harm reduction strategies
- Abstinence
- Safe sex
- Monogamous relationship
- Reduce the # of sex partners
- Vax
Human Papillomavirus Virus (HPV)
- Most common sexually transmitted infection
- Causes genital warts and cervical cancer
- Unclear incubation period (3 months-several yrs)
- Transmits thru sex or skin-skin contact
- Condoms do not provide complete protection
- No epidemiologic data yet
Altered risk of acquisition examples for HPV
a) Sex
b) Age
c) age of first sex intercourse
d) co-infections
e) male circumcision
f) condom use
g) life-time # of partners
Type 16, 18 of HPV
Cause of 70% of Cervical Cancer Cases
Type 6,11 of HPV
Cause of 90% of Genital Warts Cases
Mechanism of HPV Disease
- Micro abrasion(s) in the mucosa
- Infects basal keratinocytes (b/c quiet -> no immune response)
- Differentiate and move to the distal mucosa
- Viral assembly as cells move to the mucosa
- Infections virus shed
- Chromosomal integration (takes yrs, causes the potential for cancer)
HPV Diagnostic Approach and Treatment
- Clinical signs, pap smear, virus culture, and PCR
- b/c of high level of seroprevalence, serology is not useful
Treatment: Local therapy involving immune enhancers (imiquimod), liquid nitrogen or surgical removal
Prevention: Vaccine (can prevent strong chance of cervical cancer)
HPV Vax
- we use nine-valent now
- made with recombinant tech in which proteins form virus like particles (VLPs) of the L1 protein
- noninfectious
Herpes Simplex Viruses (HSV)
- HSV-1 and HSV-2 are both DNA viruses
- Very highly prevalent within a population
- HSV-1 more prevalent while HSV-2 less so
- Some people may not be aware bc its dormant and they never get lesions
- Most common cause of genital ulcers
- Painful lesions
- Contagious before lesions appear and with active lesions
- Recurrence more common w HSV-2
Pathophysiology of HSV
- Large family of DNA viruses
- HSV-1 above belt
- HSV-2 below belt
- Man is only natural host
- Reactivation -> you will have antivirals that will work
- Life-long infection with periodic infections
- Replicates in host cell nucleus
- Neurotropic and neuroinvasive
- Replicates 8-16hrs
HSV Transmission
- Ppl dont know their infected
- Transmission as a result of contact with mucous membrane
- HSV reactivation is linked to environmental stressors including sunlight
- Can be shared asymp.
Clinical Complications of HSV in males and females
- viral meningitis
- radiculomyelopathy with sacral nerves
- risk of acquiring and shedding HIV
- extensive vesicular skin rash
HSV treatment
- Life long
- Antiviral therapy as treatment for HSV
- Although not a cure - antiviral therapy can prevent or shorten outbreaks
- Antiviral therapy can reduce likelihood of transmitting to ones partner
Genital Herpes Clinical Diagnosis and Patient Support
- Primary episodes more severe than recurrences
- Risk of transmission to fetus during delivery
- Virus culture for lesions - can differentiate HSV-1 from HSV-2
- PCR lesions with multiplex PCR, lesions tend to be very high in viral loads
- Patient has no lesions - concerned for HSV (viral load isn’t high enough to test +’ve) - you can’t rely on a -‘ve
- Serology - looking for an antibody response
Human Immunodeficiency Virus (HIV)
- Enveloped (only survive in host cell) single stranded positive sense RNA virus
- Can’t get from kissing, or sex w barrier methods - can get from sex
- Life long infection can lead to AIDS
- HIV has tropism for CD4+ T cells of the host immune sys
- Replicates in CD4 T cells and Macrophages
- Worldwide
What is CD4
Helps -> if knocked out like in HIV you have an immune response deficiency
HIV transmission
Sexually
Pathogenesis of HIV
- Primarily in CD4 T cells found in the blood and various anatomical sites
- Infects and replicates in activated CD4 T cells
- Virus replicates in various mucosal sites including the female and male gen tract
Each STI episode or reactivation causes what to HIV RNA levels
Increase
What is HIV RNA viral load tied too
disease progression
(HIV) risk of transmitting is tied to
HIV RNA levels in blood and semen/vaginal fluid
Risk of sexually acquiring HIV
- Number of target cells at site of exposure due to inflammation increases one’s susceptibility to HIV acquisition
- STI’s recruiter cells to site of infection providing target cells for HIV to infect
Lab testing for HIV
- HIV EIA tests for p24 antigen and gp120 antibody (virus cannot escape antigen test)
- screening +’ve = has to be confirmed by a western blot
Trichomonas Vaginalis
- Most common curable STI
- Protozoan parasite, STI
- 70% asymptomatic
- More common in women
- W/o treatment can last months-yrs
- Diagnostic: wet mount looking for motile protozoa
Enteric pathogens: Bacteria
- Salmonella spp
- Shigella spp.
- E. coli
- Campylobacter spp
- Yersinia spp.
- Clostridium difficile
Enteric pathogens: Viruses
- Rotavirus
- Norovirus
- Astrovirus
- Adenovirus
- Enterovirus
Enteric pathogens: Parasites
- Entamoeba histolytica
- Giardia lamblia
- Cryptosporidium
Viral Gastroenteritis
- Syndrome of acute nausea and vomiting
- Rapid onset 1-3 days of duration
- Commonly in winter months in temperate climates (Nov to Feb)
- 2nd only to upper resp infections the cause of illness in homes
- 1-10 yr olds w 2 illness/person/yr
Viral Gastroenteritis: Syndromes
- Biggest issue: dehydration, have to eat electrolytes
- Mild afebrile illness with watery diarrhea
- More severe febrile illness with watery diarrhea, vomiting, headache, and constitutional symptoms
Norovirus
- Responsible >1/3 of outbreaks
Rotavirus
Infantile gastroenteritis
Astrovirus
Especially amongst the paediatric population
Adenovirus
- Can give you conjunctivitis, pharyngitis, gastroenteritis all @ the same time
- Up to 9% of paediatric inpatient diarrhea
Established Pathogens
- Norovirus
- Rotavirus
- Astrovirus
- Adenovirus
- Caliciviruses (other than noro)
