Background-Varicella zoster virus (VZV) vasculopathy produces stroke secondary to viral infection of cerebral arteries. Not all patients have rash before cerebral ischemia or stroke. Furthermore, other vasculitides produce similar clinical features and comparable imaging, angiographic, and CSF abnormalities.

Although the etiology of encephalitis remains unknown in most cases, the recognition of discrete clinical profiles among patients with encephalitis should help focus our efforts toward understanding the etiology, pathogenesis, course, and management of this complex syndrome.

The California Encephalitis Project was initiated in June 1998 to identify the causes and characterize the clinical and epidemiologic features of encephalitis in California. Testing for >or=13 agents, including herpesviruses, enteroviruses, arboviruses, Bartonella species, Chlamydia species, and Mycoplasma pneumoniae, was performed at the Viral and Rickettsial Disease Laboratory (Richmond, California). Epidemiologic and clinical information collected for each case guided further testing. From June 1998 through December 2000, 334 patients who met our case definition of encephalitis were enrolled. A confirmed or probable viral agent of encephalitis was found in 31 cases (9%), a bacterial agent was found in 9 cases (3%), and a parasitic agent was found in 2 cases (1%). A possible etiology was identified in 41 cases (12%). A noninfectious etiology was identified in 32 cases (10%), and a nonencephalitis infection was identified in 11 (3%). Despite extensive testing and evaluation, the etiology of 208 cases (62%) remained unexplained.

Abstract.After primary infection , varicella-zoster virus (VZV) becomes latent in ganglia. VZV reactivation occurs primarily in elderly individuals, organ transplant recipients , and patients with cancer and AIDS , correlating with a specific decl ine in cellmediated immunity to VZV. VZV can also reactivate after surgical stress. To determine whether VZV can also reactivate after acute non-su rgical stress , we examined total DNA extracted from 312 saliva samples of eight astronauts before, during and after space flight for VZV DNA by PCR: 112 samples were obtained 234 to 265 days before fl ight, 84 samples on days 2 through 13 of space flight , and 116 samples on days 1 through 15 after flight. Before space flight only one of the 112 saliva samples from a single astronaut was positive for VZV DNA. In contrast, during and after space flight , 61 of 200 (30%) saliva samples were positive in all 8 astronauts . No VZV DNA was detected in any of 88 saliva samples from 10 healthy control subjects. These data indicate that VZV can reactivate subclinically in healthy individuals after acute stress.Introduction. Primary VZV infection typically causes childhood varicella (chickenpox), after which virus becomes latent in cranial nerve , dorsal root and autonomic ganglia along the entire human neuraxis. Virus reactivates primarily in elderly individuals , as well as in organ transplant recipients and in patients with cancer and AIDS. Reactivation correlates with a specific decline in cell-mediated immunity to VZV. Although VZV also reactivates after the stress of surgery, including orofacial surgery, the relationship of VZV reactivation to non-surgical stress has not been studied .

Medical and behavioral screening does not eliminate HHV-8-seropositive persons from the US blood donor pool, but no viral DNA was found in donor blood. Further studies of much larger numbers of seropositive individuals will be required to more completely assess the rate of viremia and possibility of HHV-8 transfusion transmission. Current data do not indicate a need to screen US blood donors for HHV-8.

Immunizing infants against measles at the youngest age possible has the potential to reduce morbidity and mortality. The ability of infants at 6, 9, or 12 months to respond to measles and mumps vaccines was evaluated by measuring T cell proliferation, interferon-gamma production, and neutralizing antibody titers before and after vaccination. Infants in all age groups had equivalent cellular immune responses to measles or mumps viruses, with or without passive antibodies when immunized. In contrast, 6-month-old infants without passive antibodies had low geometric mean titers of antibody to measles or mumps viruses and low seroconversion rates. Geometric mean titers of antibody to measles virus increased if infants were revaccinated at 12 months. Six-month-old infants had limited humoral responses to paramyxovirus vaccines, whereas cellular immunity was equivalent to that of older infants. T cell responses can be established by immunization with these live attenuated virus vaccines during the first year, despite the presence of passive antibodies.

In varicella zoster virus (VZV) vasculopathy, the diagnostic value of detecting anti-VZV IgG antibody in CSF is greater than that of detecting VZV DNA. Although a positive PCR for VZV DNA in CSF is helpful, a negative PCR does not exclude the diagnosis of VZV vasculopathy. Only when the CSF is negative for both VZV DNA and anti-VZV IgG antibody can the diagnosis of VZV vasculopathy be excluded.

A statewide encephalitis diagnostic project of the California State Department of Health Services found that herpes simplex virus 1 DNA may not be detectable by molecular methods early in the clinical course of herpes simplex encephalitis.