Human Herpesviruses

Also written as Herpesvirus, HHV‑8.

Human herpesviruses (HHV‑1 to HHV‑8) cause common childhood infections and serious disease in immunocompromised children. Understanding transmission, clinical patterns and limited diagnostics in low‑resource settings guides timely management.

Overview

Human herpesviruses are DNA viruses that establish lifelong latency after primary infection. In children they range from benign exanthems to life‑threatening organ disease, especially when HIV or malnutrition is present.

• Eight species (HHV‑1 to HHV‑8)
• Latency in sensory ganglia, monocytes or endothelial cells
• Reactivation triggered by stress, illness or immunosuppression

Features of the organism

All HHVs are enveloped double‑stranded DNA viruses. They share a lytic phase (viral replication, cell death) and a latent phase (minimal gene expression, no virion production).

• γ‑herpesviruses (HHV‑4, HHV‑8) have strong oncogenic potential
• α‑herpesviruses (HHV‑1, HHV‑2) cause rapid lytic disease

Transmission and life cycle

Transmission varies: saliva (HHV‑1, HHV‑6), sexual contact (HHV‑8), blood/organ transplant (CMV, HHV‑8), and vertical (CMV). After entry the virus replicates locally, spreads to regional ganglia or bone‑marrow, and then establishes latency.

• Close contact in day‑care spreads HHV‑1 (cold sores) and HHV‑6 (roseola)
• Maternal CMV infection is a leading cause of congenital sensorineural hearing loss

Disease it causes

Clinical syndromes depend on the virus, host age and immune status. In low‑resource settings, co‑infection with HIV, malaria or malnutrition worsens outcomes.

• HHV‑1: gingivostomatitis, encephalitis (rare)
• HHV‑2: genital ulcer disease, neonatal infection
• VZV (HHV‑3): varicella, herpes zoster, cerebellar ataxia
• EBV (HHV‑4): infectious mononucleosis, endemic Burkitt lymphoma
• CMV (HHV‑5): congenital infection, retinitis in HIV, colitis
• HHV‑6/7: roseola infantum, febrile seizures
• HHV‑8: Kaposi sarcoma, especially in HIV‑positive children

Diagnosis

In many African hospitals, definitive virology is limited. Diagnosis relies on clinical patterns, basic labs and selective use of rapid tests.

• Tzanck smear (HSV, VZV): Detects multinucleated giant cells – suggests a herpesvirus but cannot differentiate species
• Serology for CMV IgM/IgG: IgM positive indicates recent infection; if unavailable, consider congenital CMV if newborn has petechiae, hepatosplenomegaly, or sensorineural hearing loss
• PCR on blood or CSF (if available): Confirms viral DNA; when unavailable, treat empirically based on syndrome

Treatment and control

Therapy focuses on antiviral agents when available, supportive care, and prevention of reactivation in high‑risk children.

• Baseline CBC and renal function before acyclovir: Ensures safe dosing; if labs unavailable, use lowest effective dose and monitor urine output
• Eye examination in VZV: Detects keratitis early; if ophthalmology not available, refer urgently

• Acyclovir (HSV, VZV) – first‑line; avoid if renal function unknown
• Ganciclovir/valganciclovir (CMV) – reserved for severe disease; monitor marrow toxicity
• No specific drug for HHV‑6/7 – treat fever and seizures symptomatically
• HAART for HIV reduces HHV‑8‑related Kaposi sarcoma

Exam pearls

Think of HHV when a child presents with a vesicular rash, fever with a characteristic exanthem, or unexplained organ disease in an immunocompromised host.

• Cold sores + fever in a toddler → HHV‑1 gingivostomatitis
• High fever > 3 days then sudden rash → HHV‑6 roseola
• Congenital sensorineural hearing loss + periventricular calcifications → CMV
• Violaceous skin lesions in HIV child → HHV‑8 Kaposi sarcoma

Questions an examiner may ask

• A 10‑month‑old presents with high fever for 4 days then a maculopapular rash that spares the trunk – what is the most likely virus and why? — HHV‑6 roseola; fever precedes rash due to viral replication then abrupt immune clearance.
• A child with known HIV develops violaceous nodules on the palate – which virus is responsible and what systemic therapy improves survival? — HHV‑8 Kaposi sarcoma; start HAART to restore immunity, consider liposomal doxorubicin if lesions threaten airway.
• A newborn has petechiae, hepatosplenomegaly and sensorineural hearing loss – which test confirms the diagnosis and what does a positive IgM indicate? — CMV PCR or IgM serology; IgM shows recent congenital infection.
• A 5‑year‑old with severe malnutrition has vesicular lesions on the lips and a painful ulcer on the tongue – which virus and what first‑line drug should you give? — HHV‑1 (herpes gingivostomatitis); give oral acyclovir, avoiding nephrotoxic drugs if renal function unknown.
• A child on chemotherapy develops fever, cough and diffuse interstitial infiltrates on chest X‑ray – which HHV should you suspect and what is the preferred antiviral? — CMV pneumonitis; give ganciclovir, monitoring blood counts.
• During a malaria outbreak, a child presents with fever, splenomegaly and a faint maculopapular rash – how do you differentiate HHV‑6 roseola from malaria? — Roseola rash appears after fever resolves; malaria shows persistent fever and positive rapid test.
• A teenager with recurrent genital ulcers tests negative for HSV PCR – what other HHV should be considered and why? — HHV‑2 (genital HSV) is most common, but HHV‑8 can cause ulcerative lesions in immunocompromised patients; consider HIV testing.
• In a resource‑limited ward, you suspect VZV encephalitis but lack PCR – what clinical clues guide treatment and what drug do you start? — Altered mental status with vesicular rash; start high‑dose acyclovir empirically.

When to seek help

• Rapid neurological decline (encephalitis)
• Severe respiratory distress from VZV pneumonia
• Unexplained severe anemia or thrombocytopenia in CMV infection
• Progressive Kaposi sarcoma compromising airway or bleeding

Quick questions

Can a child be infected with more than one HHV at once?

Yes, co‑infection is common, especially in HIV‑positive children; each virus may produce its own clinical picture.

Why is acyclovir ineffective against CMV?

CMV lacks the viral kinase that activates acyclovir; ganciclovir is required for DNA chain termination.

Is there a vaccine for any HHV?

A varicella vaccine exists and is increasingly used in low‑resource settings; no vaccine is available for HSV, CMV, EBV or HHV‑8.