S. Buxbaum

Laboratory Diagnosis of Norovirus: Which Method Is the Best?

Noroviruses (NV) are transmitted by fecally contaminated food, vomit, and person-to-person contact. They are one of the main causes of non-bacterial acute gastroenteritis in nursing, old people and children’s homes. NV outbreaks are characterized by a short incubation period (12–48 h), nausea, vomiting and diarrhea, and high secondary attack rates. The illness is generally mild and self-limiting. The aim of diagnostic procedures in viral gastroenteritis is to avoid nosocomial infections on the one hand and unnecessary antibiotic treatment on the other. Diagnostic procedures for NV are based on the detection of virus in stool samples by (immune) transmission electron microscopy (TEM), antigen ELISA, or polymerase chain reaction (PCR). In our study, a total of 244 stool samples obtained from 227 patients between March and May 2002 were tested by TEM, antigen ELISA and in-house PCR. Our data showed that PCR has the highest sensitivity (94.1%), followed by TEM (58.3%), and ELISA (31.3%), while specificity was highest for TEM (98.0%), followed by ELISA (94.9%), and PCR (92.4%). All three methods tested (TEM, ELISA and PCR) are useful for epidemiological investigations in gastroenteritis outbreaks; however, to maximize diagnostic validity for individual cases, at least two of the methods should be combined.

Loss of varicella zoster virus antibodies despite detectable cell mediated immunity after vaccination.

AbstractBackground:Vaccination of children against VZV has been included in the recommendations of the “permanent committee of vaccination” (STIKO; Ständige Impfkommission of the Robert Koch Institute, Berlin, Germany) in July 2004. Due to this recommendation the medical practitioner and the laboratories will be confronted with the problem of serologic non-responders or loss of humoral immunity more frequently.Patients and Methods:Here we report the case of a Varicella Zoster Virus (VZV) vaccinee, who lost detectable VZV antibodies although she had a persisting VZV specific CD4 cellular immune response. We compare these parameters to the VZV specific CD4 T cell responses of VZV seronegative and seropositive healthy persons, as well as patients with VZV disease.Results:VZV specific CD4 frequencies of VZV antibody seronegative persons remained on the average below 0.1% (median 0.04%, ± SD 0.03, range 0.01–0.08%) and were significantly lower than VZV specific frequencies of seropositive healthy persons (median 0.3%, ± SD 0.24, range 0.06–0.81%; Mann-Whitney U-test p = 0.001). The samples of patients with VZV associated disease showed an even higher median level of VZV specific CD4 cell response than the VZV seropositive healthy persons (median 1.04%, ± SD 1.06, range 0.51–2.92%, Mann-Whitney U-test p = 0.008). The VZV specific immune response of the health care worker directly after vaccination was comparable to the VZV specific immunity in VZV seropositive healthy adults. Despite serological reconversion 1.5 years later the VZV specific CD4 response still remained measurable and positive.Conclusion:The new general VZV vaccination recommendation for children in Germany will probably increase the number of persons that will be seronegative after vaccination. To gain more information concerning the absence of seroconversion or the loss of immunity, it will be necessary to focus future post-VZV vaccination immunity studies not only on serologic testing but also on the measuring of the cell mediated immunity.

Enterovirus infections in Germany : Comparative evaluation of different laboratory diagnostic methods

AbstractBackground: The diagnosis of an enterovirus infection may be achieved through direct virus detection from fecal or cerebrospinal fluid (CSF) samples by virus isolation or PCR. Serologically, a significant rise in antibody titer may be detected and different enteroviral types can be differentiated using the neutralization assay. Patients and Methods: We investigated the contribution of these different laboratory parameters to the diagnosis of enterovirus infections occurring in the Frankfurt am Main area during the years 1997 to 1999, including an echovirus 30 outbreak in a group of children with aseptic meningitis in 1997. Samples were referred from 1,013 patients; virus isolation was attempted from 579 CSF specimens and from 400 stool samples. 208 CSF samples were tested by PCR. Results: During the echorivus 30 outbreak we identified 22.3% of samples as positive, almost exclusively echovirus 30. In 1998 only 7.1% of samples were positive and a rather broad range of agents was isolated. In 1999 10.4% were positive, predominantly coxsackie B5 and echovirus 11. We could show that in acute enterovirus infections, virus detection by cell culture and PCR is superior to serological methods (neutralization assay and IgM assay). For virus isolation, there was a higher rate of positives from stool compared to CSF (1997: 27.8% versus 25%; 1998: 14.4% versus 3%; 1999: 17.9% versus 8.5%). When comparing PCR and virus isolation from the CSF, the former yielded a higher rate of positive results but was not clearly superior to virus isolation from CSF. Conclusion: The recommended method for the diagnosis of acute enterovirus infections is virus isolation from feces. In cases of suspected aseptic meningitis virus isolation and PCR are valuable for the direct detection of virus in CSF.

Epidemiologie der HSV-1 und HSV-2 Infektionen in Deutschland

Infektionen mit den Herpes simplex Viren (HSV) Typ 1 oder Typ 2 sind beim Menschen ubiquitar verbreitet. Die Ubertragung des HSV-1 erfolgt durch Speichelkontakt mit den Eltern bereits ab dem fruhen Kindesalter. Ein zweiter, kleinerer Durchseu-chungsschub beginnt postpubertar mit der Aufnahme von Intimkontakten. Junge Erwachsene sind in Deutschland zu ca. 80% HSV-1 Antikorpertrager. Das Virus verbleibt lebenslang in den neuronalen Zellen des Ganglion trigemini, selten in anderen Spinalganglien. Die Primarinfektion verlauft in der Regel subklinisch, im Einzelfall unter dem Bild einer schmerzhaften Stomatitis aphthosa. Ab der Pubertat kommt es, bevorzugt bei disponierten Personen, mehr oder minder regelmasig zu klinisch manifesten Rezidiven als Herpes labialis oder Herpes corneae (Lippen- bzw. Augenherpes). Selten sind die gefurchtete Herpesenzephalitis oder das Ekzema herpeticatum (als HSV-Su-perinfektion eines vorbestehenden Ekzems).