Primary human herpesvirus-6 and -7 infections, often coinciding, misdiagnosed as measles in children from a tropical region of Brazil

Abstract

We investigated primary human herpesvirus-6 and -7 (HHV-6, HHV-7) infections as a cause of rashes incorrectly diagnosed as measles in Brazilian children. Sera from 124 patients, aged 4 months to 17 years, from the states of Rio de Janeiro and Espirito Santo, in whom measles, rubella and parvovirus B19 infections had been excluded, were studied using indirect immunofluorescence antibody avidity tests; 38 (31%) had evidence of primary HHV-6 and/or HHV-7 infections. Twenty four children had primary HHV-6 infection, either recent or coincident with the rash, and similarly 31 had primary HHV-7 infection. Remarkably, almost half (17) of primary infections were dual HHV-6 and HHV-7 infections with the majority, 12 (71%), in children less than 1 year old. HHV-7 infection occurred earlier than previously reported, perhaps due to socioeconomic and tropical conditions in this region of Brazil, and thus coincided with the HHV-6 infections. This study also highlights the difficulties of diagnosing a rash illness on clinical grounds alone.

IgG subclasses and DNA detection of HHV‐6 and HHV‐7 in healthy individuals

“…However, a recent seroepidemiological study conducted in Argentina has found that children are infected with HHV-7 earlier than with HHV-6 [Bustos et al, 2006]. This observation is consistent with the infection pattern described for other developing countries [Oliveira et al, 2003]. Given that saliva of previously infected individuals is predicted to be the major source of infection for infants, the higher levels of HHV-7 compared with HHV-6 detected in our saliva samples could explain the earlier infection by HHV-7 in children from Argentina.…”

The natural history and laboratory diagnosis of human herpesviruses-6 and -7 infections in the immunocompetent

“…1). However, infection may sometimes occur earlier as reported from a tropical region of Brazil (Oliveira et al, 2003). Fig.…”

“…Exanthem subitum is often misdiagnosed as measles or rubella (Black et al, 1996a;Tait et al, 1996;Oliveira et al, 2003) despite its typical clinical features (Juretic, 1963) and the rash has also been confused with allergic reactions to antibiotics (Irving et al, 1990). As regards less easily recognised febrile illnesses, the seminal work of Hall et al (1994) showed that primary HHV-6 infection accounted for 20% of fevers between 6 and 12 months of age.…”

Detection of human herpesvirus 6 and 7 DNA in saliva from healthy adults from Rio de Janeiro, Brazil

“…It is well established that almost all children are HHV-6 seropositive by two years old (Ward et al 1993) while HHV-7 infections usually occur later, being gradually acquired over the first five or six years of life (Huang et al 1997). But infection may sometimes occur earlier, as reported in Brazil by Oliveira et al (2003). Like other herpesviruses, latency and persistence can occur in the salivary glands, peripheral blood mononuclear cells (PBMC) and central nervous system (Braun et al 1997).…”

“…Clinical diagnosis is not accurate and differential laboratory tests are necessary to distinguish exanthem subitum from viruses such as rubella, measles, human parvovirus B19 and dengue fever (Oliveira et al 2003). Primary infection is determined by the detection of low-avidity IgG antibodies, in immunofluorescent tests (Ward 2005).…”