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Clinical features and viral excretion in an infant with primary human herpesvirus 7 infection
1Department of Pediatrics, Fujita Health University School of Medicine, Aichi, Japan.
Insights
Primary human herpesvirus 7 (HHV-7) infection in a child presented with symptoms similar to human herpesvirus 6 (HHV-6). HHV-7 reactivation may trigger HHV-6 shedding.
Area of Science:
- Virology
- Pediatrics
- Immunology
Background:
- Primary human herpesvirus 7 (HHV-7) infections are common in young children.
- Distinguishing HHV-7 from HHV-6 infections can be challenging due to overlapping clinical presentations.
Observation:
- A 13-month-old boy with a history of exanthem subitum developed fever and rash, exhibiting nonspecific symptoms.
- Virological analysis confirmed primary HHV-7 infection, with viral DNA detected in peripheral blood mononuclear cells.
- The patient showed seroconversion to HHV-7, but not to HHV-6 or Mycoplasma pneumoniae.
Findings:
- HHV-7 DNA was detected in saliva and stool, followed by HHV-6 DNA in saliva.
- Mononuclear cells showed changes reacting only to HHV-7 antibodies.
- Viral shedding patterns suggest a potential link between HHV-7 and HHV-6 reactivation.
Implications:
- Clinical features of primary HHV-7 infection resemble those of HHV-6.
- HHV-7 infection might play a role in reactivating latent HHV-6.
- Understanding these interactions is crucial for pediatric viral diagnostics and management.
Objective:
To find clinical features of a virologically-confirmed patient with primary human herpesvirus 7 (HHV-7) infection and a relationship of the excretion of viruses between HHV-7 and human herpes-virus 6 (HHV-6).
Patient And Methods:
A 13-month-old boy who had a known prior history of exanthem subitum at 6 months of age developed fever for 3 days and a skin rash appeared as the fever was resolving. The course was accompanying with nonspecific signs and symptoms such as anorexia, irritability, mild diarrhea, palpebral edema, mild inflammation of pharynx, and mild occipital and cervical lymphadenopathy. Heparinized blood samples were used for isolation of HHV-6 and HHV-7 and detection of both virus DNA sequences by a nested polymerase chain reaction (PCR) amplification. Samples from other body sites were also tested for their DNA sequences using the PCR. Both virus antibody activity was measured by an indirect immunofluorescent assay or a neutralization test.
Results:
Cultured mononuclear cells from the patient at the acute stage of the disease produced morphologic changes, which reacted only with the monoclonal antibody to HHV-7 but not with the antibody to HHV-6. Both viruses were not isolated from blood obtained at the convalescent stage. An antibody response of the patient indicated a seroconversion to HHV-7 but not to other microbial agents including HHV-6 and Mycoplasma pneumoniae. Both virus DNA sequences were detected in peripheral blood mononuclear cells at acute and convalescent stages. HHV-7 DNA was excreted into saliva and transiently into stool at an early convalescent stage followed by HHV-6 excretion into saliva. No HHV-7 and HHV-6 was excreted into urine.
Conclusions:
Clinical features of a virologically confirmed patient with primary HHV-7 infection were comparable with those of primary HHV-6 infection and HHV-7 infection may reactivate HHV-6.