Since human herpesvirus 6 (HHV6) was first linked with exanthem subitum in 1988 there has been increasing evidence that the morbidity associated with acute HHV6 infection may be more significant and variable. However, the clinical appreciation of HHV6 infection has been hampered by the lack of rapid and clinically useful diagnostic methods. In this prospective study of hospitalized febrile children under 3 years of age we compared three rapid viral diagnostic methods, (polymerase chain reaction assay (PCR), IgM serology and direct antigen detection), with conventional serology on paired serum samples. In addition, we documented the range of clinical features associated with acute HHV6 infection. Of 67 children recruited, 11 (16%) had evidence of acute HHV6 infection: six had detectable, specific, IgM; four were PCR positive; and one was PCR positive with IgM. Direct antigen testing on batched frozen samples detected no infections. Apart from high fever (median peak 38.5 degrees C), common features were non-specific. Two children had febrile convulsions and only one child had a non-specific rash. We conclude that rapid microbiological diagnosis at present requires two tests (IgM and PCR). HHV6 is a common cause of febrile illness in hospitalized infants with no rash and should be considered in their diagnosis.
[Show abstract][Hide abstract] ABSTRACT: To determine whether receipt of an investigational anti-CD3 monoclonal antibody (BC3) increased the risk of human herpesvirus
6 (HHV-6) reactivation and development of encephalitis in bone marrow transplant (BMT) recipients, persons who had and had
not received BC3 were compared. Odds of HHV-6 reactivation were higher among BC3 recipients than among control patients (odds
ratio, 2.5; 95% confidence interval [CI], 1.3–4.7). In addition, BC3 recipients were more likely than control patients to
develop encephalitis (risk ratio [RR], 3.5; 95% CI, 1.3–9.5), and this association followed a BC3 dose-dependent relationship
(P=.03, by Mantel-Haenszel χ2 test). In a multivariable model, HHV-6 reactivation and receipt of BC3 were associated with increased risk of encephalitis
(RR, 5.4; 95% CI, 1.9–15.3, and RR, 3.3; 95% CI, 1.2–9.1, respectively). In conclusion, both HHV-6 reactivation and receipt
of BC3 for prophylaxis of acute graft-versus-host disease independently increased the risk of encephalitis in allogeneic BMT
recipients. Prospective studies to better define the relationship between HHV-6 reactivation and encephalitis in allogeneic
BMT recipients are warranted.
[Show abstract][Hide abstract] ABSTRACT: Human herpesviruses-6 and -7 (HHV-6/7) are widespread in all populations. In some individuals HHV-6 is found integrated into human chromosomes, which results in a high viral load in blood. HHV-6 variant B (HHV-6B) and HHV-7 primary infections, although usually silent, not infrequently cause the childhood exanthem roseola infantum and are sometimes accompanied by neurological illness. HHV-6 variant A (HHV-6A) is not associated with any disease.
The present review focuses on the immunocompetent individual and considers the epidemiology of the two viruses and their role as human pathogens. It discusses the importance of satisfactory diagnostic tests to distinguish them, compares those currently available, and recommends how best to differentiate primary from persistent infection in each case.
It is explained that at the present time antibody avidity immunofluorescence tests are the most reliable discriminators of the two types of infection. In primary infection these tests can be supplemented by PCR for viral DNA in blood but careful interpretation is required for HHV-6 in view of the high persistent viral DNA load seen with chromosomal integration. Since the contribution of primary HHV-6 and -7 infections to the burden of severe neurological illness in young children is only now emerging as significant, the need to test for these viruses in such cases is stressed.
1. Primary HHV-6/7 infections must be distinguished from persistent infections. 2. Chromosomal integration of HHV-6 requires urgent study. 3. HHV-6A/B must be distinguished in clinical situations. 4. Where serious neurological disease/encephalitis is temporally related to immunisation it is particularly important to test for HHV-6/7 primary infection since otherwise the condition might wrongly be diagnosed as a vaccine reaction. 5. Because less is currently known about HHV-7 and HHV-6A than HHV-6B, future studies should concentrate on the former two. 6. Improvements in diagnostic tests are required for each virus.
[Show abstract][Hide abstract] ABSTRACT: To evaluate the potential utility of identifying primary human herpesvirus (HHV)-6 infection in an emergency department setting by determining the frequency of HHV-6 viremia, diagnostic testing, and empiric treatment of serious bacterial infection (SBI) in HHV-6 viremic children, and concurrent SBI and HHV-6 viremia.
Children under age 2 years and who had a blood specimen taken for evaluation of fever were tested for HHV-6 by polymerase chain reaction (PCR). HHV-6 viremia was defined as detection of HHV-6 DNA in acute plasma.
A total of 32 of the 181 subjects (18%) had HHV-6 viremia. Children with HHV-6 viremia frequently underwent procedures for diagnosis and empiric treatment of SBI: 60% had bladder catheterizations, 6% had lumbar punctures, 47% had radiographs, 32% received empiric antibiotics, and 34% were hospitalized. Four of the 32 children with HHV-6 viremia (12.5%) were diagnosed with SBI, although none had a positive culture of blood or cerebrospinal fluid.
Rapid diagnosis of HHV-6 viremia may not serve to adequately differentiate infants with and without SBI in acute care settings. Although no children with HHV-6 viremia had bacteremia or meningitis, it appears that additional criteria are needed to increase the specificity of HHV-6 PCR testing before withholding evaluation for SBI.
Journal of Pediatrics 11/2006; 149(4):480-5. DOI:10.1016/j.jpeds.2006.05.027 · 3.79 Impact Factor
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