Hepatitis E virus (HEV) infections in developed countries are recognized as an imported disease related to travel to endemic regions. However, increasing evidence suggests that HEV infection may also occur in the developed countries and that swine may act as a possible reservoir. To investigate the indigenous transmission of HEV in the Netherlands, sera from 50 blood donors and 1027 sera from patients with acute hepatitis were screened with an ELISA for HEV-specific IgG and IgM. Because the Netherlands is considered a nonendemic region, all positive ELISA results were confirmed by immunoblot to exclude false-positive results. Evidence of recent HEV infection was detected in 0% of the blood donors and 4.4% of the cases, based on combined positive IgM and IgG responses. The serodiagnosis was confirmed by a positive polymerase chain reaction (PCR) in 24 patients with hepatitis (2.3% overall, 51% of confirmed IgM+/IgG+ cases). IgG antibodies alone were detected in 4.2% of patients. We found related sequences to virus strains detected in Dutch pigs (genotype 3, 91-97% homology) in 89% of PCR-confirmed HEV patients. The detection of unique swine-like HEV sequences in 16 indigenous hepatitis patients without a recent travel history suggests that HEV is endemic in the Netherlands. We recommend including HEV tests in unexplained acute hepatitis patients, despite their travel history.

Because of the occurrence of genotype 3 hepatitis E virus (HEV) in regions of low endemicity, it is important to validate the currently used serological assays for diagnosing infections with viruses belonging to this lineage, since these assays only use antigens derived from genotype 1 and 2 viruses. We evaluated the Genelabs enzyme-linked immunosorbent assay (ELISA) and the RecomBlot from Mikrogen for the detection of HEVspecific immunoglobulin M (IgM) and IgG under conditions of low endemicity. We compared test results of 16 patients with locally acquired genotype 3 HEV, 8 genotype 1 patients, 167 healthy controls from the general population, and 101 cases with hepatitis due to other viral causes. The measured specificities of the ELISA (98%) and the RecomBlot (97%) were comparable to those given by the manufacturer for IgM but were significantly lower for IgG (93% by ELISA and 66% by immunoblotting, versus reported values of 98% for ELISA and 95% for blotting). Antibody levels detected following infections with genotype 3 were lower than those following genotype 1 infections except for those measured in the IgM ELISA. Reactivity to the four antigens used in the immunoblot assay were analyzed and showed differences in the IgM immunoblot reactions between genotype 1 patients and genotype 3 patients. The ORF3 antigen was the most specific antigen. The specificity could be improved by a combined testing regimen with confirmation by immunoblotting of all positive ELISA results and by raising the cutoff of the IgG immunoblot assay without loss of sensitivity. We conclude that a combination of ELISA and immunoblotting is needed for acceptable specificity and sensitivity of HEV assays under conditions of low endemicity.Hepatitis E is an acute self-limiting disease that is common in Asia and Africa and considered emerging in many industrialized countries. After the discovery of the hepatitis E virus (HEV) by electron microscopy in 1983 and its subsequent characterization (2), HEV infections have been reported over a wide geographic area in Asia, Africa, the Middle East, and Central America (1). The lineages that are endemic in these regions differ antigenically and genetically and have been labeled Birma-like (genotype 1), Mexico-like (genotype 2), and China-like (genotype 4). In addition, besides travel-associated HEV infections, several reports have now shown indigenous circulation of a fourth lineage of HEV (genotype 3), both in humans and in swine in regions of the world previously considered free from HEV (3,8,10,(13)(14)(15)(16)(17).HEV infections are recognized in The Netherlands as an imported disease related to travel to regions of endemicity but also as a result of indigenous transmission of HEV. In the travel-related cases, genotype 1 is frequently detected, whereas most locally acquired HEV cases are caused by genotype 3 viruses. In view of the increasing awareness of the occurrence of HEV in regions with a temperate climate, it is important to validate the currently used serological assays for diagnosis o...

The Netherlands has experienced large community outbreaks of Q fever since 2007. Sera and questionnaires containing epidemiological data from 5654 individuals were obtained in a nationwide seroprevalence survey used to evaluate the National Immunization Programme in 2006-2007. We tested these sera for IgG phase-2 antibodies against Coxiella burnetii with an ELISA to estimate the seroprevalence and to identify determinants for seropositivity before the Q fever outbreaks occurred. Overall seroprevalence was 1·5% [95% confidence interval (CI) 1·3-1·7]. Corrected for confirmation with immunofluorescence results in a subset, the estimated seroprevalence was 2·4%. Seropositivity ranged from 0·48% (95% CI 0·00-0·96) in the 0-4 years age group to 2·30% (95% CI 1·46-3·15) in the 60-79 years age group. Keeping ruminants, increasing age and being born in Turkey were independent risk factors for seropositivity. The low seroprevalence before the start of the outbreaks supports the hypothesis that The Netherlands has been confronted with a newly emerging Q fever problem since spring 2007.

SHepatitis E virus (HEV) is now considered an endemic pathogen in industrialized countries, leading to acute and sometimes chronic hepatitis, mostly in vulnerable people. The endemic sources are unclear. A survey in The Netherlands in 2006-2007 showed a 1·9% seroprevalence of HEV antibodies measured by ELISA and confirmed by immunoblot in a nationwide sample. Overall, in 134/7072 (1·9%) seropositive individuals, older age (P<0·01), being male (P<0·01), working with patients (P=0·03), working with animals (P=0·07), recent diarrhoeal complaints (P=0·07) and adhering to a religion that considers pigs unclean (P<0·01) were independently associated with seropositivity in multivariate analysis. Sub-analysis of 59/4022 (1·5%) anti-HEV antibody-positive subjects with probable endemic exposure showed independent association with youngest household member being aged <5 years or between 19 and <65 years (P=0·05) in multivariate analysis. These findings may contribute to a better understanding of the sources of endemic HEV exposure, and also highlight the need for systematic epidemiological and serological evaluation of new cases.

We report the recent epidemiology and estimated seroprevalence of human hantavirus infections in the Netherlands. Sixty-two cases were reported during December 2008–December 2013. The estimated seroprevalence in the screened municipalities in 2006–2007 was 1.7% (95% CI 1.3%–2.3%). Findings suggest that hantavirus infections are underdiagnosed in the Netherlands.

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Cat scratch disease (CSD) is caused by Bartonella henselae infection and is a common cause of regional lymphadenopathy. The diagnosis of CSD largely depends on serology, but detection of B. henselae in an affected lymph node by PCR is also an important diagnostic tool. We evaluated an IgM in-house ELISA protocol and analyzed its performance in routine CSD serology. Serum samples from PCR-positive patients (n = 126), PCR-negative patients (n = 123), and age-matched controls (n = 126) were used for evaluation. The sensitivity of the IgM ELISA was only 56%, showing that the performance of B. henselae serology under routine laboratory settings is low, probably caused by the wide variability in disease duration in patients suspected of CSD whose samples were submitted to our laboratory. Most patients (46%) with a positive IgM response were between 0 and 20 years of age. We conclude that the serodiagnosis of B. henselae is hampered by the low sensitivity and specificity of the assays when used in a routine laboratory setting. For this reason, a negative IgM or PCR result can never exclude CSD, especially with late sample collection.

A putative underdiagnosis of clinical chikungunya virus infection in Dutch travelers to the Indian Ocean area was addressed by retrospective screening of all sera for which requested dengue virus serology was negative in the period 2007 to 2010. Evidence for a recent infection was observed in 6.5% of 107 patients, indicating a substantial underdiagnosis and the need for increased awareness among physicians.