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Biomedical subjects

H L Zaaijer

Publications and source records attributed to H L Zaaijer.

At least 19 recordsLinked to original sources
PubMed2006

Hepatitis B virus (HBV) DNA levels and the management of HBV-infected health care workers.

Different guidelines exist for the management of hepatitis B virus (HBV)-infected health care workers (HCWs). Various HBV DNA levels are used as a cutoff level to determine whether an HBV-infected HCW is allowed to perform exposure-prone procedures (EPPs) or not. In this paper we discuss the factors that determine HBV DNA levels and the implications of different HBV DNA cutoff levels for EPP performing HCWs. If the level of HBV DNA in the serum of HCWs is used to determine acceptability for the conduct of EPPs, it is necessary to take into account the variability in time of HBV DNA levels in HBV carriers and the reliability and reproducibility of the molecular diagnostic test involved. The issue of standardization has to be addressed, before a universal, maximum level of viraemia for EPP performing HCWs can be introduced.

DNA, Viral↗
PubMed2005

Human parechovirus infections in Dutch children and the association between serotype and disease severity.

BACKGROUND: Human parechoviruses (HPeVs) are members of the family Picornaviridae and are classified into 3 known serotypes: HPeV1, HPeV2, and the recently identified HPeV3. HPeV1 and HPeV2 infections are most commonly associated with mild respiratory or gastrointestinal symptoms and occasionally with severe disease conditions, such as flaccid paralysis and encephalitis. HPeV3 infection has been associated with transient paralysis and neonatal infection and has until now only been reported in Japan and Canada. METHODS: Culture isolates considered to be enterovirus on the basis of cell culture but that were found to be enterovirus negative by 5' untranslated region reverse-transcriptase polymerase chain reaction (5'UTR RT-PCR) during the period December 2000 through January 2005 were selected. Isolates were tested by HPeV 5'UTR RT-PCR and were genotyped by sequencing the VP1 region. Phylogenetic analysis was performed, and the association with clinical symptoms was established. RESULTS: Thirty-seven (12%) of the 303 isolates that tested positive for enterovirus by cell culture were in fact HPeV. The majority of the HPeV-positive isolates (n = 27) could be identified as HPeV1. The remaining 10 isolates, which were grown from samples obtained in 2001, 2002, and 2004, could be typed as the recently identified HPeV3. HPeV was exclusively detected in children aged < 3 years. Children infected with HPeV3 were significantly younger than children infected with HPeV1, and sepsis-like illness and central nervous system involvement were more frequently reported in children infected with HPeV3. CONCLUSIONS: We report HPeV infections in young children during the period of 2000-2005 and show an association between HPeV3 infection and sepsis-like illness and central nervous system involvement in neonates.

Central Nervous System Infections↗
PubMed2005

Occult hepatitis B virus infection before and 1 year after start of HAART in HIV type 1-positive patients.

Occult hepatitis B virus (HBV) infection is diagnosed when HBc antibodies and HBV-DNA are detectable in serum while hepatitis B surface antigen (HBsAg) is not. The clinical relevance of this phenomenon in HIV-1 patients starting highly active antiretroviral therapy (HAART) is unknown. We followed 93 therapy naive HIV-1-infected adults who were anti-HBc positive, HBsAg and HBeAg negative, during first year of HAART. At baseline, HBV-DNA was quantified, and HBV genotype was determined in the HBV-DNA-positive patients by sequencing a part of the HBV genome. Four of 93 patients (4%) were HBV DNA positive at baseline. All four patients tested negative for HBV-DNA after 1 year. They all received lamivudine as part of their HAART. They had no clinically significant liver enzyme elevations (LEE) during the first year of HAART. Two of the patients had a genotype A, one genotype E, and in the fourth patient sequencing was not possible. In one patient we found significant mutations in the a determinant region of HBsAg, at positions 142 and 144. In our population of therapy-naive HIV-1-infected adults who were anti-HBc positive, we found occult HBV infection in 4% of the patients. We did not find an increased risk for LEE in our population of patients after the start of HAART. Our results illustrate that occult HBV infection is more a diagnostic than a clinical problem. It may be caused by very low levels of HBV replication, concurrent presence of HBsAg and anti-HBs, or mutations in the HBsAg a determinant.

Adult↗
PubMed2004

Diversity and origin of hepatitis B virus in Dutch blood donors.

Two considerations led us to study the genetic diversity and origin of hepatitis B virus (HBV) in Dutch blood donors. Firstly, an HBV-infected Dutch blood donor was found negative by four assays used commonly for detection of HBV surface antigen (HBsAg). How variable is HBsAg among HBV infected blood donors? Secondly, the WHO recommends universal vaccination against HBV, but north-west European countries limit vaccination to groups at risk of HBV. This policy may reduce hepatitis B among low-risk, unvaccinated persons if HBV strains that infect low-risk persons stem from local at-risk groups. Studying the nucleotide sequence of the S-gene of HBV from 63 Dutch blood donors, considerable variation was found. The majority of the donor strains (52/63, 83%) appears closely related to local HBV isolates as present in intravenous drug users, immigrants, and homosexual men. The remaining 11 (17%) HBV strains belong to various non-Western genotypes. This implies that an indigenous Dutch HBV strain (heterosexually transmitted, not associated with intravenous drug abuse, or immigrants) does not exist, and it supports the policy in low endemic countries to limit vaccination to at-risk groups. On the other hand, it must be realised that, after 20 years of vaccination of at-risk groups, HBV still circulates in the at-risk groups and Dutch blood donors acquire the HBV strains involved.

Amino Acid Sequence↗
PubMed2004

Parvovirus B19 viraemia in Dutch blood donors.

Blood, donated by asymptomatic donors, may contain and transmit parvovirus B19. To investigate the dynamics of parvovirus viraemia in asymptomatic blood donors, we studied the amounts of parvovirus DNA in pools of donor plasma, the prevalence of parvovirus antibodies among blood donors in relation to age, and the seasonal and year-to-year variation of the incidence of parvovirus infection in The Netherlands. The incidence of parvovirus infection follows a seasonal cycle and a cycle of several years. Among Dutch blood donors the incidence was estimated to be 0.56% per year. Forty seven out of 100 pools of 5000 plasma donations tested positive for parvovirus DNA. We inferred that the course of viraemia in asymptomatic donors shows a short peak (> 10(9) copies parvovirus DNA/ml), followed by viraemia below 10(6) copies/ml for about 2 weeks.

Adolescent↗
PubMed2003

[ 'Severe acute respiratory syndrome' (SARS) in perspective].

In the Netherlands, the risk of an outbreak of the severe acute respiratory syndrome (SARS) appears to be limited, if people in contact with a possibly imported case observe strict measures to prevent contamination. SARS may well be a zoonosis. Bovine spongiform encephalopathy and outbreaks of virus infections in the bioindustry, such as swine fever, foot-and-mouth disease and classical avian influenza, have led to massive killing of cattle, swine and fowl in the Netherlands. The possibility that the bioindustry constitutes a risky microbiological 'experiment' makes a discussion as to its future in the Netherlands urgent.

Animals↗
PubMed2003

Successful treatment of subcutaneously disseminated aspergillosis with caspofungin acetate in an allogeneic peripheral blood stem cell transplantation patient.

We present a patient with acute myeloid leukaemia who developed subcutaneously disseminated aspergillosis after allogeneic peripheral stem cell transplantation (PSCT). Disseminated aspergillosis after stem cell transplantation has a high mortality despite treatment with amphotericin B or one of the azoles. Aspergillosis in our patient was refractory to amphotericin B and itraconazole but was successfully treated with caspofungin acetate.

Antifungal Agents↗
PubMed2002

[Interpretation of the increase in bovine spongiform encephalopathy outside Great Britain].

Outside Great Britain, the number of clinical cases of bovine spongiform encephalopathy (BSE) seems to be rising. It is unclear whether this increase is real, or whether it is caused by improved recognition and improved registration of BSE. A strict and independent control of the implementation of measures intended to keep human food free of the BSE agent is imperative.

Animals↗
PubMed2001

[Meningococcal disease in the Netherlands: media hype, but not an epidemic].

An outbreak of meningococcal disease caused by Neisseria meningitidis C, type 2a recently occurred in the Dutch province of West-Brabant. Five children were affected and two of these died. The Outbreak Management Team decided to start a local vaccination campaign with a meningococcal group C conjugate vaccine. The publicity surrounding these cases of meningococcal disease led to much anxiety throughout the Netherlands. Despite parent's concerns, there is nothing to indicate the presence of an epidemic.

Adolescent↗
PubMed2001

Early detection of hepatitis B surface antigen and detection of HBsAg mutants: a comparison of five assays.

BACKGROUND AND OBJECTIVES: Assays for the detection of hepatitis B surface antigen (HBsAg) face two challenges: the emergence of sensitive techniques for detection of hepatitis B virus DNA and the existence of HBsAg mutant hepatitis B viruses. We studied the sensitivity of five modern assays for detection of HBsAg. MATERIALS AND METHODS: The sensitivity of two mini robot-based assays--IMx HBsAg V2 and Vidas HBsAg--and three enzyme-linked immunosorbent assays (ELISAs) with microtitre plate format--Hepanostika Uni-Form II v1.2, Monolisa Ag HBs Plus and HBsAg Test System 3--was compared testing 11 HBsAg seroconversion series, serial dilutions prepared from three HBsAg standards and nine HBsAg mutant samples. RESULTS AND CONCLUSION: Overall, the IMx HBsAg V2 assay showed the highest sensitivity. It outperformed the Vidas HBsAg in analytical sensitivity and in detection of HBsAg mutants. Among the microtitre plate ELISAs, the Monolisa Ag HBs Plus outperformed the HBsAg Test System 3 in detection of HBsAg mutants and it surpassed the Hepanostika Uni-Form II v1.2 in analytical sensitivity.

Diagnostic Equipment↗
PubMed2000

[Confusion surrounding bovine spongiform encephalopathy (BSE) and the risk of new variant Creutzfeldt Jakob disease].

There is a lot of confusing news regarding the risks of consuming beef for contracting variant Creutzfeldt Jakob disease. Bureaucratic inertia and political expediency are fueled by the lack of pathogenetic and epidemiologic understanding of the mode of transmission. Consumers discard beef from their diet, which may be the least contaminated tissue, but other meat products, of which the risks are probably much higher, continue to enjoy free international trade and may be used in the human diet. British beef may be less harmful than French sausage. In addition, criminal and fraudulent practices pose a considerable threat to which an appropriate political answer has yet to be formulated.

Animals↗
PubMed2000

[Bovine spongiform encephalopathy and food safety].

The governments of Great Britain and France disagree on the safety of British beef with respect to bovine spongiform encephalopathy (BSE). Eventually the consumer might have the burden to decide whether beef from Britain is safe to eat with regard to the new variant of Creutzfeldt-Jakob disease (vCJD). Outside Britain the incidence of BSE increases. Probably in continental Europe, the use of high risk material, derived from non-British cattle in the subclinical stage of BSE, poses a greater threat than beef imported from Great Britain. The risk to contract vCJD depends on two unknown factors: the susceptibility of man to BSE and the amount of success in keeping infectious tissue of BSE-incubating cattle out of the human food chain. Until the susceptibility of humans to BSE and the extent to which our food is contaminated become known, no clear-cut advice can be given on the safety of certain food items. There appears to be a genetic predisposition to vCJD, i.e. methionine homozygosity at codon 129 of the normal human prion protein gene. The European Community should ban the use of any high risk material for production of food, except in production processes for which inactivation of the BSE agent has been proven. The facts that are known at this moment allow the conclusion that gelatin and beef products of unknown origin and composition pose a greater health threat than eating genuine beef (muscle tissue).

Animals↗
PubMed1999

[Transmission of hepatitis B virus by a surgeon].

A Dutch surgeon transmitted hepatitis B virus (HBV) to several of his patients (8 certain cases, 2 probable cases and 18 possible cases). To view this accident in the proper context, we estimated the incidence of HBV transmission in the Netherlands from surgeons to patients (1/37,000 surgical procedures) and from patients to non-immune surgeons (0.8%/surgeon/year). The incident as such is alarming because of the high frequency of HBV transmission that occurred. However, the number of infections involved was lower than the expected number of iatrogenic HBV infections in the Netherlands during the given period. It is advisable to quickly implement the WHO guidelines, demanding universal HBV vaccination of infants, and to organize vaccination of risk groups (including medical personnel) in the Netherlands.

Adult↗
PubMed1999

[Whipple's disease].

Whipple's disease is characterized by malabsorption, weight loss, diarrhoea and abdominal pain, often preceded by a long period of migrating arthralgias. Instead of the intestine the heart, brain, eyes, lungs or blood vessels may be affected. Whipple's disease is caused by Tropheryma whippelii, a bacillus found inside phagocytes. A specific defect in the immune system of the host appears to play a part. The diagnosis is based on microscopic examination of periodic-acid-Schiff(PAS)-stained slides and on polymerase chain reaction (PCR) analysis of affected tissue. Recently a method for culturing T. whippelii was described. Prolonged treatment with cotrimoxazole, preceded or not by two weeks of penicillin and streptomycin, often cures the disease, but relapses do occur.

Anti-Bacterial Agents↗
PubMed1998

Hepatitis G virus RNA and hepatitis G virus-E2 antibodies in Dutch hemophilia patients in relation to transfusion history.

The prevalence of hepatitis G virus (HGV)-RNA and HGV-E2 antibodies was studied in a cohort of Dutch hemophilia patients in relation to clotting products used, age, and coinfection with hepatitis C. Between 1991 and 1995, blood samples were taken from 294 patients with hemophilia A, B, or von Willebrand disease. From each patient one fresh frozen sample was tested for HGV cDNA polymerase chain reaction (PCR) and HCV cDNA PCR. Alanine aminotransferase (ALT) tests were performed on plasma samples of all patients. The presence of HGV-E2 antibodies was tested on plasma samples from a subset of 169 patients representing all age groups. Based on the origin and viral safety of the products used, three subgroups of patients were distinguished. Group A: patients who used viral noninactivated factors derived from small and large donor pools; group B: patients who used factors prepared with inadequate viral inactivation techniques derived from small and large donor pools; and group C: patients treated only with optimally viral inactivated large pool clotting factor or recombinant clotting factor concentrate. The prevalence of HGV-RNA was 18%. In group A patients the prevalence was 71%, in group B 50%, and in group C 6%. When related to age, the highest prevalence of HGV-RNA (35%) was seen in patients born between 1980 and 1989. The prevalence of HGV-E2 antibodies increased with age. Of HGV-RNA-negative patients born before 1950, 96% tested positive. HGV viremia did not affect ALT levels, neither in HCV-RNA positive nor in HCV-RNA negative patients. HGV infection is frequently seen in patients with hemophilia. In older age groups a lower rate of HGV-RNA positivity is seen coinciding with a higher rate of antienvelope antibodies.

Age Factors↗
PubMed1998

Validation of a new immunoblot assay (LiaTek HIV III) for confirmation of human immunodeficiency virus infection.

BACKGROUND: Used as a supplemental assay, new anti-human immunodeficiency virus (HIV) immunoblots, employing recombinant and synthetic antigens, appeared to resolve the majority of samples with false-reactive Western blot results. Would it be possible to completely replace the Western blot by an immunoblot for confirmation and exclusion of HIV infection? STUDY DESIGN AND METHODS: The sensitivity of the new LiaTek HIV III immunoblot assay (Organon Teknika, Turnhout, Belgium) was tested on 416 Western-blot positive samples (386 HIV-1, 22 HIV-2, 1 HIV-1/2, and 7 HIV-O) and on 45 HIV-1 seroconversion samples. The specificity was tested on 146 samples from noninfected donors with false-positive results on a HIV screening test. RESULTS: All Western-blot-positive samples tested positive in the immunoblot (sensitivity: 100%). The immunoblot could not discriminate between HIV-1 and HIV-2 infection in 22 of 416 (5%) samples. The LiaTek assay showed reactivity in 28 of 45 seroconversion samples, whereas the Western blot reacted in 30 of 45 seroconversion samples. With false-positive donor samples, the immunoblot was indeterminate in 10 of 146 samples (specificity: 93%), and the Western blot was indeterminate in 44 of 146 samples (specificity: 70%). CONCLUSION: Like the Western blot, the immunoblot runs the risk of missing samples that are reactive by enzyme immunoassay during the early stage of HIV infection. Nevertheless, considering its superior specificity on false-positive donor samples, it appears that the immunoblot offers a cost-effective alternative to the Western blot assay for confirmation and exclusion of HIV infection.

AIDS Serodiagnosis↗