Infectious Mononucleosis: Symptoms and Epidemiology

Infectious Mononucleosis

• Infectious mononucleosis can cause a rash in some patients.
• The Epstein-Barr virus (EBV) causes infectious mononucleosis.
• Petechiae on the hard and soft palates can be seen in 25–60% of patients diagnosed with infectious mononucleosis
• A widely scattered, erythematous maculopapular rash occurs in 10–15% of those diagnosed with infectious mononucleosis.
• Maculopapular rashes are more common in young children.
• Infectious mononucleosis may be misdiagnosed as streptococcal pharyngitis, leading to treatment with amoxicillin or ampicillin.
• About 80% of patients with EBV mononucleosis who are treated with amoxicillin or ampicillin may develop a widespread maculopapular rash.
• To avoid antimicrobial agents, Streptococcus pyogenes pharyngitis should be ruled out before treatment.

Infectious Mononucleosis – Epidemiology

• EBV is found worldwide and is common.
• Most people are seropositive for EBV by age 25.
• EBV is transmitted via saliva, sexual contact, organ transplantation, or blood transfusions from infected or convalescent persons.

Infectious Mononucleosis – Pathogenesis

• EBV infects the B cells in the oropharyngeal epithelium.
• The B cells spread the infection throughout the reticuloendothelial system.
• The virus is present in immune complexes, which are responsible for arthralgia and rash during the acute phase.

Infectious Mononucleosis – Diagnosis

• Complete blood count (CBC) shows leukocytosis with lymphocytosis and atypical lymphocytes.
• Serologic findings for EBV includes positive heterophile antibody tests (Monospot and Paul-Bunnell tests).
• EBV-specific serology can be tested: VCA IgM, EA IgG, EBNA IgG.

Secondary Syphilis

• Syphilis has three stages: primary, secondary, and tertiary.
• The stage with the most prominent skin lesions is secondary syphilis.
• Secondary Syphilis involves many maculopapular lesions.
• Syphilis is caused by Treponema pallidum.
• T. pallidum is visualized through darkfield microscopy.

Secondary Syphilis – Clinical Manifestations

• In neonatal syphilis, the lesions can be vesicular, bullous, or maculopapular.
• Secondary syphilis lesions can be seen on the palms and soles.
• Secondary syphilis’ lesions may regress naturally, but relapses can occur in 20% of untreated patients.

Syphilis – Epidemiology/Pathogenesis

• An inflammatory reaction occurs causing a hard chancre (raised edematous ulcer).
• Histologic examination of the chancre demonstrates endarteritis and periarteritis and infiltration of the ulcer with macrophages and PMNs.
• Syphilis is an STI, mostly contracted by sexually active men and women aged 20–45 years.
• Following contact with broken skin, T. pallidum penetrates and enters the blood and spreads throughout the body, including the skin.
• The immune response causes mucocutaneous lesions with maculopapular lesions on the skin.
• All lesions contain viable and highly infectious T. pallidum.

Secondary Syphilis Diagnosis

• Diagnosis includes a complete history, physical exam, serologic tests, and darkfield microscopy of fluids from lesions.
• Serologic tests used: screening tests and confirmatory tests.
• The screening test is a non-treponemal test.
• It detects the presence of antibodies reactive with cardiolipin.
• VDRL and RPR tests detect non-treponemal serologic antibodies, but false positives can occur; a confirmatory test is needed after a positive screening result.
• Confirmatory or treponemal tests include T pallidum immobilization (TPI), fluorescent treponemal antibody absorption (FTA-ABS), and micro-hemagglutination assay for T pallidum (MHА-ТР).

Secondary Syphilis Treatment and Prevention

• Benzathine penicillin is the antibiotic of choice for treatment of primary and secondary syphilis.
• Preventive measures identifying and treating sexual contacts and avoiding sexual contact with other syphilitic patients can help stop the spread.

Rocky Mountain Spotted Fever (RMSF)

• Rocky Mountain spotted fever (RMSF) is the most common rickettsial tick-borne infection in the United States.
• RMSF is caused by Rickettsia rickettsii, an obligate intracellular bacterium transmitted via a tick bite.

RMSF – Skin Manifestations

• Most RMSF patients present with a rash 3 days after the bite.
• A unique manifestation is a rash that begins as erythematous macules on the wrists and ankles.

Toxic Shock Syndrome (TSS)

• Toxic shock syndrome (TSS) is an uncommon but severe systemic life-threatening disease that follows exposure to a bacterial superantigen produced by certain strains of S. aureus and S. pyogenes.
• The most common cause of TSS is S. pyogenes strains producing either superantigen SPE A or C.
• S. aureus can also cause TSS.
• Staphylococcal TSS can occur during menstruation or after a localized staphylococcal infection (non-menstrual TSS).
• With staphylococcal TSS, the superantigen exotoxin TSS toxin-1 (TSST-1) or enterotoxins is a factor.

Toxic Shock Syndrome – Clinical Manifestations

• Streptococcal TSS is group A streptococcal infection plus early shock/organ failure.
• In only about 10% of patients with streptococcal TSS is a diffuse scarlatina-like erythema seen.
• Staphylococcal TSS is defined as acute-onset illness with fever, hypotension, and rash; this can lead to multi-organ failure and shock.
• The rash appears later in the disease and has a sunburn-like appearance on the palms and soles.

Toxic Shock Syndrome – Epidemiology

• People of any age can be affected, with many without predisposing conditions
• Infections such as chickenpox and influenza have provided a portal for infection.
• The mortality rate of streptococcal TSS is 30–70%.
• Streptococcal TSS occurs after an invasive infection (e.g., bacteremia, pneumonia).
• Infection begins at a site of minor local trauma.
• Many cases have developed within 24-72 hours of minor non-penetrating trauma.
• Non-menstrual staphylococcal TSS commonly follows superinfection of an upper respiratory tract after viral infection.
• Other staphylococcal infections such as infected surgical wounds, abscesses, infected burns, and deep and superficial soft tissue infections can cause non-menstrual TSS.
• Menstrual staphylococcal TSS occurs during menstruation or within 2 days before or after.
• Menstrual staphylococcal TSS is associated with tampon use.
• The mortality rate is about 5% for both menstrual and non-menstrual TSS.

Toxic Shock Syndrome – Diagnosis

• Streptococcal TSS can be difficult to diagnose.
• Clinical and laboratory criteria can aid in determining the diagnosis.
• The Centers for Disease Control and Prevention (CDC) has defined clinical criteria for diagnosing TSS.

Toxic Shock Syndrome – Treatment and Prevention

• Treatment includes aggressive fluid replacement and IV treatment with antibiotics (e.g., oxacillin or nafcillin).
• For non-menstrual TSS, removing the localized staphylococcal infection is essential.
• Care for streptococcal TSS includes identifing the site of infection, surgical debridement, aggressive fluid replacement, and intravenous antibiotics.
• Frequent handwashing and measures to prevent spread of these superantigen-producing bacteria can be helpful.