Chapter: Sexually Transmitted Infections

Question 1

Viral STI: Human Papilloma Virus (HPV)

Answer 1

• Causes genital warts
• Virtually all cervical cancers are caused by HPV
• Also causes anal, vaginal, vulvar, and penile cancers
• HPV been found to cause cancer of oropharynx likely through oral sex (more than half of diagnosed cases are linked to HPV-16)
• Prevention: Vaccination (Gardasil)
• Most infections clear up on their own
• MOST PREVALENT (common STI in NA)

Question 2

Progression of HPV

Answer 2

• Most HPV infections clear up with no serious consequences.
• In 5-10 % of infected women the infection persists > 2 years.
• Infections appear to clear up faster in men.
• Persistent infection has high risk of developing pre-cancerous cervical changes, which can lead to cervical cancer in 10-15 years.
• This long latency provides ample opportunity to remove pre-cancerous cells if they are identified (e.g., by Pap tests)

Question 3

Viral STI: Herpes Simplex Virus 1 and 2 VERY COMON

Answer 3

• HSV-1: cold sores
• HSV-2: genital herpes
• Lies dormant in nerves
• -During times of stress, virus will migrate to skin and start replicating
• If you treat sores quickly, reduction in causing cancer where virus resides
• Infection is for life
• Difficult to prevent, 2/3 North Americans carry this virus, no cure
• Prevalence is -50-60% for HSV1 and 7-20% for HSV2

Question 4

Herpes Simplex Virus (HSV) Progression

Answer 4

• Travels along nerves and lays dormant in nerve cells; infection is life-long
• Contagious if carrier is shedding the virus (usually when sores are visible)
• Prevention difficult (especially for HSV-1)because human reservoir is so large (~2/3)North American adults carry the virus
• Most people are infected as children
• Acyclovir can abate symptom

Question 5

Viral STI: Hepatitis Virus (A, B , C ,D, E, F , G)

Answer 5

• Causes inflammation of the liver
• Fever, headaches, fatigue, stiff/aching joints, nausea/vomiting, diarrhea, jaundice
• Hep A/E transmitted by contaminated water (fecal-oral)
• Hep B/C/D transmitted through intimate contact of body fluids (blood, sexual, or sharing needles).
• Hep A/B vaccine available in Canada. Two doses are recommended 6- 18 months apart (TwinRix vaccine).
• -C in development
• Most new infections of Hep C among people who inject drugs or partake in high risk sexual behaviours.

Question 6

Vital STI: Human Immunodeficiency Virus (HIV)

Answer 6

• Transmission
• -Not spread by casual contact
• -Most common: unprotected sex
• –frequent sexual activity with multiple, anonymous partners and high-risk sexual practices such as anal intercourse
• • Injection-drug users who share contaminated needles are at high risk
• -Infected mother can transmit HIV to fetus
• No Vaccine

Question 7

HIV Transmission Inside the Body

Answer 7

• HIV infects immune cells
• -Destroys the cell-mediated immune system (T cells)
• The immune system does launch an immune response against it (ex. Antibodies), so why can’t the immune system get rid of it?
• -HIV “hides” inside immune cells (and kills them)
• -HIV replicates too fast for our immune system to fight it
• -HIV mutates (therefore changing its antigens), to avoid elimination
• HIV Testing measures antibodies

Question 8

AIDS

Answer 8

• An untreated HIV infection typically leads to AIDS within 10 years
• Severely compromises immune system
• -Death due to opportunistic infections
• HAART: main treatment
• -Highly Active AntiRetroviral Therapy
• -Combination of (usually) 3 different drugs

Question 9

Bacterial STI: Chlamydia

Answer 9

• Most common bacterial STI, 2x likely in women
• Common and easily treatable
• If left untreated, can lead to ectopic pregnancy, sterility
• Can be passed from mother to infant during childbirth
• Treatment: Antibiotics
• Prevention: condom use
• -Reported more with females
• -Most common reported STI in Canada
• Symptoms:
• Burning while urinating
• -PID (pelvic Inflammatory Disease)
• -Disrupted menstruation
• -Pelvic pain
• -Nausea/vomiting
• -Discharge
• -Dysuria

Question 10

Bacterial STI: Syphilis

Answer 10

• Three stages: Primary, secondary, tertiary
• -Primary: Sore/lesion- can go unnoticed
• -Secondary: rash on hands, feet or all over
• -Tertiary: Irreversible damage to nervous syst. & disfigurement as tumour-like masses from under skin/in organs
• –Heart failure, blindness, mental disturbance
• Treated with antibiotics
• Prevention unprotected sex
• Tuskegee Syphilis Experiment

Question 11

Bacterial STI: Gonorrhea

Answer 11

• Often asymptomatic
• Can spread and cause inflammation of epididymis, prostate, urethra, cloudy penile discharge, dysuria in MEN
• Can spread and cause PID, green/yellowish discharge in WOMEN
• Of ~450 million new curable STI cases each year, ~90 million are gonorrhea (WHO)
• In Canada, number of cases has been rising since 1990s
• Treated with antibiotics; prevention = condom use

Question 12

Factors that put young people at risk

Answer 12

• Feelings of invulnerability
• Multiple partners
• Being unaware of a partner’s history
• Infidelity
• Failure to use protection
• Use of alcohol and/or drugs
• Lack of STI testing