Unit 3 - Chapter 27 Sexually transmitted infections

Question 1

Gonorrhea

Answer 1

• sexually transmitted communicable disease (local or systemic)
• complications - pelvic inflammatory disease (PID), sterility, and disseminated infection (goes to other body organs)
• can be passed to fetus from the mother [conjunctivitis (manifests as an eye infection 1-12 days after birth; opthalmic antibiotic prophylaxis is not enough to stop vertical transmission (in utero or breasty feeding; mostly delivery))

bacteria - neisseria gonorrheae - can infect lining of urethra, cervix, rectum or thorat, or membranes that fron part of eye (conjunctiva and cornea)
* usually have discharge from penis or vagina (may need to urinate more frequently and urgently)
* condoms can help with transmission
* vaginal, oral, or anal sexual conduct

sx -
men (2-14 days after)
* discomfort in urethra
* dysuria
* yellow-green discharge
* urgency
* scrotal swelling (epididymis)

female
* peritonitis (PID) -lower abdominal pain + fever sometimes
* concentrate around liver => pain, fever, and vomiting (Fitz-Hugh-Curtis syndrome)
* sx doesn’t happen until 10 days after
* such as mild discomfort in genital area or yellow-green discharge
* more severe - frequent urge or dysuria [urethra infected]

throat - gonococcal paryngitis => no sx; maybe sore
anal - gonococcal proctitis => painful bowels, constipation, itching, bleeding, discharge

disseminated gonoccocal infection (arthritis-dermatitis syndrome) => bloodstream => esepcially skin and joints
* joints swollen, tender, painful, limits mvmt
* skin over infected joints - red and warm
* fever, ill, pain d/t arthritis in one or more joints
* small red spots on arms and legs (may fill with pus)
* heart sometimes infected

tx: ceftriaxone

Question 2

Syphillis

Answer 2

• becomes systemic shortly after infection

4 stages of disease
1) primary syphillis w/ chancre (ulcer or sore - firm, round and painless + sometimes open w/ moisture)
* nearby lymph nodes may be enlarged, firm and nontender

2) secondary syphillis w/ systemic spread to all body systems (via bloodstream)
* widespread mucocutaneous lesions, lymph node sweel
* 6-12 weeks after chance appear (25% may still have them)
* fever, loss of appetite, nausea, fatigue
* headache (meningitis), hearing loss d/t otitis, balance problems (labyrinthitis), visual disturb, bone pain
* all lesions eventually heal w/o scarring
* syphillitic dermatitis (palms and soles); round + scale + coalesce to form large lesions that do not hurt or itch
* condyloma lata: hypertrophic, flattened, dul pink or gray papules in mucocutaneous junctions and moist regions of skin (perianal, under breasts); very infectious; mouth/throat/larynx/penis/vulva/ rectum [circular, raised, gray to white w/ red border]
* other organs w/ lesions: eyes (uveitis), bones (periositis), joints, meninges, kidneys (glomerulitis), liver (hepatitis), spleen

3) latent syhpilis with minimal sx of developing skin lesions
* less than or more than 1 year after infection
* s/s absent, antibodies positive via STS or serologic tests for syphilis
* may relapse w/ contagious skin or mucosal lesions during early latent period
* AB may cure latent phase

4) tertiary syphilis, most severe - destroy bone, skin, soft + neurolgic tissue
* decades later; 1/3 develop late syphilis
* Benign tertiary gummatous syphilis usually develops within 3 to 10 years of infection and may involve the skin, bones, and internal organs. Gummas are soft, destructive, inflammatory masses that are typically localized but may diffusely infiltrate an organ or tissue; they grow and heal slowly and leave scars.
* Benign tertiary syphilis of bone results in either inflammation or destructive lesions that cause a deep, boring pain, characteristically worse at night.
* Cardiovascular syphilis usually manifests 10 to 25 years after the initial infection as any of the following:
1. Aneurysmal dilation of the ascending aorta (compress and erode other structures in chest)
2. Insufficiency of the aortic valve
3. Narrowing of the coronary arteries
a) l/t brassy cough and obstruction of breathing + erosion of sternum and ribs or spine
Neurosyphilis
1) asymptomatic neurosyphilis - meningitis => 5% l/t symptomatic neurosyphilis
2) Meningovascular neurosyphilis - inflammation of large- to medium sized arteries in brain or spinal cord; 5-10 years after infection. Sypmtoms include - headache, neck stiff, dizzy, bx abnormal, poor conc, memory loss, insomnia, blurred vision, lassitude (lack of energy)
* spinal cord involvement => shoulder-girdle + arm muscle weakness, leg weakness, incontience, parayliss of legs
3) Parenchymatous neurosyphilis - general paresis or dementia paralytica; chronic meningoencephalitis destroys cortical parenchyma (15-20 yrs after infection, older than 40s or 50s)
SYMPTOMS
* irritable, poor conc, memory deteriorated, poor judgement, headache/insomnia/fatigue/lethargy
* seizure, tranisent hemiparesis, and aphsia possible
* emotionally unstable - depressed, grandiose thoughts
* tremors of mouth, tongue, hands, whole body
* pupillary abnormalities
4) tabes dorasalis - locomotor ataxa; slow degeneration of psoterior columns and nerve roots
* 20-30 years afterwards
* earliest sx - intense stabbing (lightning) pain in back and legs that recurs irregularly w/ loss of vibratory sense, proprioception and reflexes in lower extremities
* gait ataxia (loss posture, imbalance, uncoordinated walking)
* thin w/ sad facies + argyll robertson pupils (accomodate for near vision but do not respond to light)

**spirochete Treponema pallidum **
* genital ulcers, skin lesions, meningitis, aortic disease, neurologic syndromes
* genital, orogenital, anogenital
* can be transmitted skin contact or transplacentally causing congenital syphillis
* 30% in sex encounter and 80% from mother to fetus
* analgesics.. and carabamazepine tid or qid

tx
* Benzathine penicillin G for most infections
* Aqueous penicillin for ocular syphilis or neurosyphilis (or procaine penicillin G 2.4 million units IM qd + 500 mg probenecid qid)
* Treatment of sex partners
* For penicilin allergies - ceftriazone 2 g IM or IV qd for 14 days can be effective

The treatment of choice in all stages of syphilis and during pregnancy is
The sustained-release penicillin benzathine penicillin (Bicillin L-A)
The combination of benzathine and procaine penicillin (Bicillin C-R) should not be used.

Question 3

Jarisch-Herxheimer reaction (JHR)

Answer 3

Most patients with primary or secondary syphilis, especially those with secondary syphilis, have a JHR within 6 to 12 hours of initial treatment. It typically manifests as malaise, fever, headache, sweating, rigors, anxiety, or a temporary exacerbation of the syphilitic lesions. The mechanism is not understood, and JHR may be misdiagnosed as an allergic reaction.

JHR usually subsides within 24 hours and poses no danger. However, patients with general paresis or a high CSF cell count may have a more serious reaction, including seizures or strokes, and should be warned and observed accordingly.

Unanticipated JHR may occur if patients with undiagnosed syphilis are given antitreponemal antibiotics for other infections.

Question 4

Congenital syphillis

Answer 4

• prematurity of newborn with
• bone marrow depression, CNS involvement, renal failure, and intrauterine growth retardation

Question 5

Chrancroid infection

Answer 5

• bacteria Haemophilus ducreyi => causes ulcers usually of genitals
• sexual transmission through skin-to-skin contact with open sore(s). non-sexual transmission when pus-like fluid from the ulcer is moved to other parts of the body or to another person.
• women - generally asymptomatic
• men - develop inflamed, painful genital ulcers and inguinal buboes (swollen inflamed lymph node)
• Incubation 1-14 days
• Single dose therapy w/ injectable ceftriaxone or oral azithroycin for both partners is recommended

Question 6

Ganuloma inguinale

Answer 6

• donovanosis
• rare in U.S
• intracellular gram-negative bacterium Klebsiella granulomatis
• they survive within macrophages
• localized nodules coalesce to form granulomas and ulcers on the penis in men and libia in women
• AB effective
• sexual contact

Question 7

Bacterial vaginosis

Answer 7

• overgrowth of anaerobic bacteria that make aromatic amines and pH of vagina promoting further bacterial growth (w/ no inflammatory resposne) and fishy oder
• CLUE cells are found on the wet mount (vaginal smear) — Clue cells are certain cells in the vagina (vaginal epithelial cells) that appear fuzzy without sharp edges under a microscope. Clue cells change to this fuzzy look when they are coated with bacteria. If clue cells are seen, it means bacterial vaginosis is present.
• Metronidazole (flagyl) effective tx
• condition associated with pelvic inflammatory disease, chorioamnionitis (infection of placenta and amniotic fluid), preterm labor, postpartum endometritis
• TX of male sex partner not recommended

Question 8

Chlamydia

Answer 8

• most common bacterial STI in US
• leading preventable cause of infertility and ectopic pregnancy
• C. trachomatis - localizes to epithelial tissue and spread thoruhg urogenital tract or pass from infect mother to eyes + respiratory tract of newborn infants during bith
• Single-dose azithromycin drug of choice
• asymptomatic nature of chlamydia and potential after effects [widespread screening needed]

2) Chlamydia pneumoniae (children, young adult); community acauired pneumonia (hoarseness and osre throat precede coughing)
3) Chlamydia psittaci (spread from birds to humans)

Question 9

Lymphogranuloma venereum

Answer 9

• chronic STI uncommon in U.S
• C. trachomatis serovars L1, L2, or L3 (strain of chlamydia bacteria); sex men w/ men
• lesion begins as a skin infection => spread to lymph tissue causing inflammation, necoriss, buboes (nlarged lymph node that is tender and painful), abscesses (pocket of pus) of inguinal lymph nodes
• Primary lesions appear on penis + scrotum of men while, female, on cervix, vaginal wall, and labia
• Secondary lesions (evolve from primary) involve inflammation + swelling of lymph nodes with formation of large buboes that rupture and drain
• 21 day or longer course of oral doxycycline or erthyromycin is needed for treatment
• tx of parter recommended

Question 10

Genital herpes

Answer 10

• most common genital ulceration
• HSV-1 or HSV-2 (herpes simplex virus)
• After the initial infection, HSV remains dormant in nerve ganglia, from which it can periodically emerge. When the virus emerges, it may or may not cause symptoms (ie, genital lesions). Transmission may occur through contact with the lesions or, more often, via skin-to-skin contact with sex partners when lesions are not apparent (called asymptomatic shedding).
• lesions starts as group of vesicles that progress to ulceration w/ pain, lymphadenopathy (swelling of lymph nodes), and fever
• can pass from mother to fetus (recommended to give birth by cesarean to avoid vertical transmission)

HSV infection is lifelong and result in an inital outbreak and subsequent outbreaks
* individuals are contagious during outbreaks and episodes of asymptomatic viral shedding

acyclovir reduces sx but does not cure disease

• recurrent infections are attributable to HSV-2 and are milder a nd of shorter duration

sx:
Primary genital lesions develop 4 to 7 days after contact. The vesicles usually erode to form ulcers that may coalesce. Lesions may occur in the following locations:
* On the prepuce, glans penis, and penile shaft in men
* On the labia, clitoris, perineum, vagina, and cervix in women
* Around the anus and in the rectum in men or women who engage in receptive rectal intercourse
* Urinary hesitancy, dysuria, urinary retention, constipation, or severe sacral neuralgia (pain in nerve pathway) may occur.

Scarring may follow healing. The lesions recur in 80% of patients with HSV-2 and in 50% of those with HSV-1.

Primary genital lesions are usually more painful, prolonged, and widespread, involve regional adenopathy, and are more likely to be accompanied by constitutional symptoms than recurrent genital lesions. Recurrent lesions tend to be milder and cause fewer symptoms.

tx

Acyclovir, valacyclovir, or famciclovir

Genital herpes is treated with antiviral drugs.

Question 11

Human papillomavirus (HPV)

Answer 11

• development of cervical dysplasia and cancer + condylomata acuminata [genital warts]
• high risk strains (HR-HPV) are precursors to development of cervical cancer that do not cause genital warts
• testing avaiable to detect HR-HPV and vaccine available for specific high risk HPV types

Important manifestations of anogenital HPV include
* Genital warts (condyloma acuminatum)
* Intraepithelial neoplasia and carcinoma of the cervix, vulva, vagina, anus, or penis
* Laryngeal and oropharyngeal cancers
* Bowenoid papulosis (an uncommon sexually transmitted condition that occurs in both males and females. It is characterized by multiple well-demarcated red-brown to violaceous papules in the genital area.)

In most cases (9 out of 10), HPV goes away on its own within two years without health problems.

Question 12

Condylomata acuminata

Answer 12

• genital warts
• velvety caulifolwer-like lesions => genital, anal, vagina, cervix, are painless; can be transmitted at birth

Question 13

Mollsucum contagiosum

Answer 13

• benign viral infection of skin
• skin-to-skin contact for children and adults
• tends to occur on genitalia and transmitted by sexual cotact\
• poxvirus (molluscum conagiosum virus)
• round firm painless bumps (pinhead to eraser size) – scratched or injured the infection can spread to nearby skin

Question 14

Trichomoniasis (T. vaginalis)

Answer 14

• causes vaginitis in women and urethranitis in men
• both partners usually infected
• women - copioius, malodorus gray green discharge with pruitus
• Men - asymptomatic
• Tx - metronidazole (nitroimidazole antimicrobials)

Question 15

Scabies

Answer 15

• parasitic infection via skin-to-skin or sexual contact
• scaabies mite burrows through skin and lays eggs causing intense pruitius (particularly at night)
• pediculicide - topical applcator

Question 16

Pediculosis pubis

Answer 16

• crabs
• transmitted via sex and caused by crab louse (wingless parasite insect that lives on skin of mammals), P. pubis; lice bite into skin for nutrition => mild to severe pruitius
• permethrin or a mousse containing pyrethrins and piperonyl butoxide can be used to treat pubic (“crab”) lice.

Question 17

HIV/AIDs

Answer 17

• human immunodeficiency virus (retrovirus) causes acquired immunodeficiency
• weakens your immune system
• Common infections and cancers that define AIDs -
  1) Fungal infection of esophague [food pipe], brain, lungs
  2) Tuberculosis
  3) Kaposi sarcoma - cancer that causes painless red or purple blotches on your skin or inside your mouth
  4) Non-hodkin lymphoma and other cancers
  5) Pneumocytis pneumonia, toxoplasmosis, and cytomegalovirus (usually can fight off before)
• AIDS pts have “AIDS wasting” or severe weight loss
• Infections that also occur in the general population but suggest AIDS if they are unusually severe or frequently recur include

1. Herpes zoster
2. Herpes simplex
3. Vaginal candidiasis
4. Invasive pneumococcal infections
5. Salmonella septicemia

HIV
* virus takes over a CD4 lymphocyte, it makes many copies of itself before killing the CD4 cell and releasing the virus copies. Those copies then take over other CD4 lymphocytes, which make even more copies. This cycle continues until there are billions of HIV in your body
* Contact w/ body fluids - blood, semen, vaginal fluids, or breast milk (rarely - tears, urine, or saliva)
* Can get via unprotected sex, sharing needles, or pregnancy/childbirth/breastfeeding

sx:
* fever
* rash
* lumps in neck, under arms, and groin [swollen lymph nodes]
* weak/tired
* ALL last 3-14 days then go away and then have few or no sex for years

Symptoms during this relatively asymptomatic period may result from HIV directly or from opportunistic infections. The following are most common:

Lymphadenopathy
White plaques due to oral candidiasis
Herpes zoster
Diarrhea
Fatigue
Fever with intermittent sweats

Asymptomatic, mild-to-moderate cytopenias (eg, leukopenia, anemia, thrombocytopenia) are also common. Some patients experience progressive wasting (which may be related to anorexia and increased catabolism due to infections) and low-grade fevers or diarrhea.

Viral load
* amount of HIV in your blood (lower the better)
* Blood tests to see how much CD4 cells (CD4 count)
* Low CD4 count means weaker immune system

====================================

Two main consequences of HIV infection are

• Damage to the immune system, specifically depletion of CD4+ lymphocytes
• Immune activation

CD4+ lymphocytes are involved in cell-mediated and, to a lesser extent, humoral immunity. CD4+ depletion may result from the following:

• Direct cytotoxic effects of HIV replication
• Cell-mediated immune cytotoxicity
• Thymic damage that impairs lymphocyte production

1) Humoral response affected - hyperplasia of B cells in lymphnodes => lymphadenopathy (swelling of lymph nodes) => hyperglobulinemia (globulins fight infection)
2) Total antibody levels (epescially IgG and IgA) and titers [analysis that detects the presence and measures the amount of such antibodies in a person’s blood] for previously encountered antigens unsually high
3) Antibody response to new antigen decreases as CD4 decreases
4) HIV also infects other cells (dendritic cells in skin, macrophages, brain microglia), and cells of b rain, genital tract, heart, kidneys
5) Cell-mediated immunity important in controlling initial viremia => but loses control shortly

• CD4 count < 200/mcL: Increased risk of Pneumocystis jirovecii pneumonia, toxoplasmic encephalitis, and cryptococcal meningitis
• CD4 count < 50/mcL: Increased risk of cytomegalovirus (CMV) and Mycobacterium avium complex (MAC) infections

For every 3-fold (0.5 log10) increase in plasma HIV RNA in untreated patients, risk of progression to AIDS or death over the next 2 to 3 years increases about 50% (6).

Without treatment, risk of progression to AIDS is about 1 to 2%/year in the first 2 to 3 years of infection and about 5 to 6%/year thereafter. Eventually, AIDS almost invariably develops in untreated patients.

Staging

HIV infection can be staged based on the CD4 count. In patients ≥ 6 years old, stages are as follows:

• Stage 1: ≥ 500 cells/mcL
• Stage 2: 200 to 499 cells/mcL
• Stage 3: < 200 cells/mcL

The CD4 count after 1 to 2 years of treatment provides an indication of ultimate immune recovery; CD4 counts may not return to the normal range despite prolonged suppression of HIV.

========

AIDS is defined as HIV infection with one or more of the following:

1. One or more AIDS-defining illnesses (1)
2. A CD4+ T lymphocyte (helper cell) count of < 200/mcL
3. A CD4+ cell percentage of ≤ 14% of the total lymphocyte count

AIDS-defining illnesses include

1. Serious opportunistic infections
2. Certain cancers (eg, Kaposi sarcoma, non-Hodgkin lymphoma) to which defective cell-mediated immunity predisposes
3. Neurologic dysfunction
4. Wasting syndrome

=============
Treatment of HIV Infection

• Combinations of antiretroviral drugs (antiretroviral therapy [ART], sometimes called highly active ART [HAART] or combined ART [cART])
• Chemoprophylaxis for opportunistic infections in patients at high risk

Immunization for HIV infected:
* pneumococcal vaccine
* influenza vaccine
* hepatitis b vaccine
* hepatitis A vaccine
* HPV
* menigococcal vaccine (every 5 yrs) 8 weeks apart for 2 dose series
* recombinant zzoster vaccine
* varicella vaccine (contraindicated in patients w/ CD4 % <15 and CD4 count <200

When these people w/ high CD4 and low HIV levels [first infection] acquire a superinfection with a second strain of HIV to which their immune response is not as effective, they convert to a more typical pattern of progression. Thus, their unusually effective response to the first strain does not apply to the second strain. These cases provide a rationale for counseling people infected with HIV that they still need to avoid exposure to possible HIV superinfection through unsafe sex or needle sharing.

Question 18

Cytomegalovirus

Answer 18

• human herpesvirus type 5
• transmitted via blood, fluids, transplated organs; infection can acquired transplacentally or during birth
• Congenital CMV infection may be asymptomatic or may cause abortion, stillbirth, or postnatal death. Complications include extensive hepatic and central nervous system (CNS) damage.
• In immunocompromised patients, CMV is a major cause of morbidity and mortality. Disease often results from reactivation of latent virus. The lungs, gastrointestinal tract, or CNS may be involved. In the terminal phase of AIDS, CMV infection causes retinitis in up to 40% of patients and causes funduscopically visible retinal abnormalities. Ulcerative disease of the colon (with abdominal pain and gastrointestinal bleeding) or of the esophagus (with odynophagia) may occur.
• usually latent, asymptomatic [neonates at risk d/t age?]

Question 19

Epstein-barr virus

Answer 19

EBV infection is very common; the virus remains within the host for life and is intermittently and asymptomatically shed from the oropharynx.
[EBV, human herpesvirus type 4]

Only about 5% of patients acquire EBV from someone who has acute infection.

Typical manifestations include fatigue (sometimes persisting weeks or months), fever, pharyngitis, splenomegaly, and lymphadenopathy.

Uncommon severe complications include encephalitis and other neurologic manifestations, splenic rupture, airway obstruction due to tonsillar enlargement, hemolytic anemia, thrombocytopenia, and jaundice.

tx —
Provide supportive care and recommend avoidance of heavy lifting and contact sports; antivirals are not indicated.

Consider corticosteroids for complications such as impending airway obstruction, severe thrombocytopenia, and hemolytic anemia.

Question 20

HBV hepatitis b virus

Answer 20

Hepatitis B virus (HBV) is the most thoroughly characterized and complex hepatitis virus. The infective particle consists of a viral core plus an outer surface coat. The core contains circular double-stranded DNA and DNA polymerase, and it replicates within the nuclei of infected hepatocytes. A surface coat is added in the cytoplasm and, for unknown reasons, is produced in great excess.
* needle puncture, blood transfusion, cuts in the skin, and contact with infected body fluids.
* chronic liver disease, hepatocellular cancer
* Best prevention - immunization (infant, children, high-risk adult)

Hepatitis B is often transmitted by parenteral contact with contaminated blood but can result from mucosal contact with other body fluids.

Infants born to mothers with hepatitis B have a 70 to 90% risk of acquiring infection during delivery unless the infants are treated with hepatitis B immune globulin (HBIG) and are vaccinated after delivery; risk is also decreased by treating actively infected third trimester pregnant mothers who have high viral loads with tenofovir.

Chronic infection develops in 5 to 10% of patients with acute hepatitis B and often leads to cirrhosis and/or hepatocellular carcinoma.

Diagnose by testing for hepatitis B surface antigen and other serologic markers.

Treat supportively.
Routine vaccination beginning at birth is recommended for all.

Postexposure prophylaxis consists of HBIG and vaccine; HBIG probably does not prevent infection but may prevent or attenuate clinical hepatitis.

Supportive care

For fulminant hepatitis B, antiviral drugs and liver transplantation

Question 21

Hepatitis C

Answer 21

• transfer percuatenously but sexual transmission appears possible
• Hepatitis C is a common cause of chronic hepatitis. It is often asymptomatic until manifestations of chronic liver disease occur. Diagnosis is confirmed by finding positive anti-HCV and positive HCV RNA ≥ 6 months after initial infection. Treatment is with direct-acting antiviral drugs; permanent elimination of detectable viral RNA is possible.

Question 22

Hepatitis D

Answer 22

Hepatitis D is caused by a defective RNA virus (delta agent) that can replicate only in the presence of hepatitis B virus. It occurs uncommonly as a coinfection with acute hepatitis B or as a superinfection in chronic hepatitis B.

Suspect hepatitis D particularly when cases of hepatitis B are severe or when symptoms of chronic hepatitis B are worsening.

Treat and prevent infection as for hepatitis B.

• chronic hepatitis D is interferon-alfa, although pegylated interferon-alpha is likely equally effective. Treatment for 1 year is recommended, although whether longer treatment courses are more effective has not been established. Bulevirtide is available for treatment of hepatitis D in Europe

Question 23

Hepatitis A

Answer 23

Hepatitis A is caused by an enterically transmitted RNA virus that, in older children and adults, causes typical symptoms of viral hepatitis, including anorexia, malaise, and jaundice. Young children may be asymptomatic. Fulminant hepatitis and death are rare in countries that have adequate and effective water treatment and sanitation facilities. Chronic hepatitis does not occur. Diagnosis is by antibody testing. Treatment is supportive. Vaccination and previous infection are protective.

Hepatitis A virus is the most common cause of acute viral hepatitis; it is spread by the fecal-oral route.

Children < 6 years old may be asymptomatic; older children and adults have anorexia, malaise, and jaundice.

Fulminant hepatitis is rare, and chronic hepatitis, cirrhosis, and cancer do not occur.

Treat supportively.

Routine vaccination beginning at age 1 is recommended for all.

Vaccinate people at risk (eg, travelers to endemic areas, laboratory workers), and provide postexposure prophylaxis with standard immune globulin or, for some, vaccination.

• fecal-oral content; poor hygiene

Question 24

Hepatitis E

Answer 24

Hepatitis E is caused by an enterically transmitted RNA virus and causes typical symptoms of viral hepatitis, including anorexia, malaise, and jaundice. Fulminant hepatitis and death are rare, except during pregnancy. Diagnosis is by antibody testing. Treatment is supportive unless chronic infection develops.

Genotypes 1 and 2 usually cause waterborne outbreaks that are linked to fecal contamination of the water supply and fecal-oral person-to-person transmission

Genotypes 3 and 4 typically cause sporadic cases rather than outbreaks. Transmission is food-borne and can involve eating uncooked or undercooked meat; cases have been associated with consumption of pork, deer, and shellfish.

Transmission of hepatitis E is usually by the fecal-oral route.

Most patients recover spontaneously, but pregnant women have an increased risk of fulminant hepatitis and death.

Genotype 3 may cause chronic hepatitis in immunocompromised patients.

Suspect hepatitis E in travelers to endemic regions; do IgM anti-HEV testing if available.

Treat patients supportively; consider using ribavirin for chronic hepatitis E.

A vaccine is available in China.

Question 25

Zika virus

Answer 25

• normally transmitted via mosquito bites
• but also sexual contac twith infected body fluids or through vertical transmission
• sequesters in fetal brain tissue, disrupting brain growth and causing persistent, lifelong microcephaly.