Seroprevalence of hepatitis E virus in the UK farming population

Hepatitis E is a zoonosis that can be acquired by the consumption of contaminated food or water, or via person-to-person spread. However, little is known about the transmission of hepatitis E virus (HEV) in the UK. We investigated the epidemiology of indigenous hepatitis E infection using the PHLS Farm Cohort, a sentinel group with a history of close contact with a range of domestic animals. Ten of the 413 subjects tested were positive for hepatitis E IgG antibodies (2.4%). Seroprevalence peaked in those aged 51 to 60 years (relative risk 3.3, 95% CI: 1.0-10.5). Male participants (relative risk 3.6, 95% CI: 0.6-21.2) and those from farms in the Hereford area of the United Kingdom (relative risk 2.7, 95% CI: 0.8-8.4), an area of mixed livestock farming, were more likely to have serological evidence of previous HEVs exposure, although these findings were not statistically significant. Exposure to pigs, or water from a private supply, was not identified as a significant risk factor. The results of this study suggest that UK farming populations are exposed to HEV, but the predominant route of transmission remains elusive.

Neurological disease associated with Mycoplasma pneumoniae infection. PCR evidence against a direct invasive mechanism

Aims-To investigate the pathology in patients presenting with sudden onset neurological illnesses associated with Mycoplasma pneumoniae infection.Methods-M pneumoniae infection was diagnosed by a highly rigorous interpretation of serological markers initially using complement fixation, agglutination and IgM antibodies. Confirmation of the serological diagnosis was achieved using indirect immunofluorescence for IgM, IgA, and IgG. Serum and cerebrospinal fluid (CSF) samples from these patients were examined using the polymerase chain reaction to look for evidence of M pneumoniae DNA.Results-No M pneumoniae DNA was found in any serum or CSF samples. Diagnosis of M pneumoniae infection by agglutination and complement fixation antibodies was not always confirmed by indirect immunofluorescence.Conclusion-The neurological lesions in these patients do not appear to be caused by the direct invasion of M pneumoniae into the nervous system. The lesions may be an immune response to infection. Serological diagnosis of M pneumoniae continues to be a laboratory problem.

No evidence of the Chlamydia trachomatis variant in the UK

OBJECTIVES

The discovery of a variant strain of Chlamydia trachomatis (Ct) in Sweden has raised awareness of its possible undetected spread in the UK. The assays that fail to detect this variant are widely used in this country. This study aimed to determine if this variant is circulating in the UK.

METHOD

1,680 genital specimens tested negative by the Roche assays were retested by Aptima Combo2. Discordant results were sequenced to check for the deletion variant.

RESULTS

Of 1,680 specimens tested, 29 were candidates for sequencing: 16 were negative for the variant, 11 failed to amplify, and 2 were lost.

DISCUSSION

No Ct deletion variants were found in the UK. If it is circulating, then the prevalence is low (0-0.77%), but even a low level cannot be ignored. The system we describe is simple and suitable for rapid response and phasing of surveillance to match an unknown level of threat if other variants emerge.

Microbiological profile of community-acquired pneumonia in adults over the last 20 years

OBJECTIVES

To assess any change in the microbiological profile of community-acquired pneumonia (CAP) in our region over the last 20 years.

METHODS

We compared hospital admissions aged between 15 and 74 (n = 61) in Norfolk (UK) for CAP over a 19-month period in 1982-3 (ST1) with all admissions aged over 16 (n = 99) over a 14-month period in 1999-2000 (ST2). Data were collected for ST1 as part of a prospective multicentred research study, in a period of high Mycoplasma pneumoniae activity. ST2 was a prospective study of clinical practice. Chlamydophila species were differentiated in ST2 using whole-cell immunofluorescence.

RESULTS

A microbiological diagnosis was made in 38 (62%) in ST1 compared with 48 (48%) in ST2. Streptococcus pneumoniae remained the most common pathogen (26% in ST1, 25% in ST2). The incidence of M. pneumoniae was 18% in ST1 and 4% in ST2. The proportion of viral pathogens identified was similar: nine (15%) in ST1 and 14 (14%) in ST2. No cases of Chlamydophila pneumoniae were diagnosed in ST2.

CONCLUSIONS

The microbiological profile of CAP in Norfolk (UK) has not changed over the last 20 years and C. pneumoniae is not a frequent pathogen.

Mental health of British farmers

AIMS

To estimate the prevalence of neurotic symptoms in a sample of British farmers, to investigate whether farming characteristics are associated with psychiatric morbidity, and to test the hypothesis that British farmers have a higher prevalence of depression and thoughts of life not worth living than the British household population.

METHODS

A total of 425 farmers from Hereford, Norwich, and Preston completed the Revised Clinical Interview Schedule (CIS-R) by computer between March and July 1999. The comparison cohort consisted of 9830 private householders aged 16-64 from the Office of Population Censuses and Surveys National Psychiatric Morbidity Surveys of Great Britain carried out in 1993 in which the CIS-R was administered. All analyses used the commands developed specifically for survey data available in Stata version 6.0.

RESULTS

Taking a threshold of an overall score of 12 or more on the CIS-R, only 6% of farmers reported clinically relevant psychiatric morbidity. Psychiatric morbidity was not significantly associated with farm type or size in this study. Farmers reported a lower prevalence of psychiatric morbidity than the general population but were more likely to report thinking that life is not worth living, particularly after the low prevalence of psychiatric morbidity had been taken into account (odds ratio 2.56, 95% CI 1.39 to 4.69). When restricting the comparison to only rural or semirural householders, this increased risk was even more pronounced (odds ratio 3.26, 95% CI 1.51 to 7.02).

CONCLUSIONS

The relation between depression and suicidal ideation seems to be quite different among farmers and the general population and warrants further investigation. We have shown it is possible to measure mental health systematically in a sample of British farmers. This study should be repeated in the aftermath of the foot and mouth crisis.

Evidence of persisting serum antibodies to Escherichia coli O157 lipopolysaccharide and Verocytotoxin in members of rural communities in England

The techniques of enzyme-linked immunosorbent assay (ELISA) and immunoblotting were used to examine a total of 1667 sera, from apparently healthy members of rural communities in England, for antibodies to the lipopolysaccharide (LPS) of Escherichia coli O157 and Verocytotoxins (VT). Twenty-nine sera from 22 individuals were shown to have antibodies specific for E. coli O157 LPS. Some of these lived on livestock farms and had occupational contact with cattle, suggesting that personnel working with farm animals may produce serum antibodies to the O157 LPS antigens. Fifteen people had IgG class antibodies to O157 LPS, suggesting long-term exposure to E. coli O157 and five people had serum antibodies on more than one occasion showing evidence of persistent antibodies to O157 LPS. Thirteen sera from 12 of 22 individuals also contained antibodies to VT1, VT2 or both toxins. Ten sera contained antibodies to VT1 and VT2, three sera contained antibodies to VT2 only.

Simple method for determining biovar and serovar types of Ureaplasma urealyticum clinical isolates using PCR-single-strand conformation polymorphism analysis

Ureaplasma urealyticum has been associated with urethritis in men, obstetric problems in women, and respiratory distress syndrome in preterm infants. U. urealyticum can be divided into two biovars comprising 14 serovars. Partial sequences of genes encoding the multiple-banded antigens of the cell surface are known. Using a commercially available precast DNA mutation detection gel system, we have developed a simple and reproducible PCR-single-strand conformation polymorphism analysis method for differentiating the biovars of this species that reveals five patterns among the 14 serovars and enables clinical isolates to be typed directly from broth cultures.

Orf (contagious pustular dermatitis) in farmworkers: prevalence and risk factors in three areas of England

Orf is a zoonotic skin disease which is commonly self-diagnosed by those who tend sheep and goats. This paper reports the prevalence, incidence and risk factors associated with the infection in a cohort of farmworkers from three areas of England, derived from the results of self-reporting and serology. Twenty-three per cent of those employed or living on a sheep farm reported ever having had orf, and the antibody serological profiles indicated a prevalence of 4 per cent and an annual incidence of 2.8 per cen. The main risk factors associated with the infection were contact with sheep, the size of the sheep flock, and contact with dogs.

Multiplex polymerase chain reaction for the simultaneous detection of Mycoplasma pneumoniae, Chlamydia pneumoniae, and Chlamydia psittaci in respiratory samples

AIMS

To develop a multiplex polymerase chain reaction (PCR) for the simultaneous detection of Mycoplasma pneumoniae, Chlamydia pneumoniae, and Chlamydia psittaci in respiratory samples.

METHODS

Oligonucleotide primers for the amplification of the DNA of these three organisms were optimised for use in combination in the same reaction. PCR products were detected by hybridisation with pooled internal probes using an enzyme linked immunosorbent assay. Those with positive signals were further differentiated using species specific probes. Quality of DNA extraction and PCR inhibition were controlled by amplification of a human mitochondrial gene. A panel of 53 respiratory samples with known results was evaluated blindly. This was followed by a retrospective study on sputa collected from 244 patients with suspected community acquired pneumonia.

RESULTS

The multiplex assay had a lower sensitivity than PCR with individual primers by about one log. The resultant sensitivity was considered acceptable for diagnostic use. Of the panel of 53 samples, nine of 11 M pneumoniae, 11 of 11 C pneumoniae, six of seven C psittaci, and 24 of 24 negative samples were correctly identified. Of the 244 patients with pneumonia, seven (2.9%) had detectable M pneumoniae, six (2.5%) had C pneumoniae, and one (0.4%) had C psittaci. The case notes from 11 patients were studied. The PCR finding was of possible significance in at least eight of these patients.

CONCLUSIONS

This multiplex PCR assay has the potential to be used as a diagnostic and epidemiological tool. Further prospective studies are needed to establish its clinical value.

Low rates of ehrlichiosis and Lyme borreliosis in English farmworkers

To determine the occupational significance of tick-borne zoonoses we sought serological evidence of Lyme borreliosis, human monocytic ehrlichiosis (HME) and human granulocytic ehrlichiosis (HGE) in a representative sample of farmworkers. Although around 20% reported ticks on their domestic and companion animals, few (< 2% per year) reported being bitten by ticks. Seroprevalence of Lyme borreliosis (0.2%), HME (0.2%) and HGE (1.5%) was low. Those seropositive for HGE were no more likely to report tick bites nor more likely to report ticks on their animals. This study provides evidence that farmworkers in England are exposed to tick-borne zoonoses but that they are uncommon. Since the severity of these diseases is linked to delays in diagnosis and treatment, clinicians should be aware of these diagnoses in patients from rural communities, with or without a self-reported history of tick bite.

Anticomplementary activity in serum samples from patients with acute parvovirus B19 infection

Of 65 serum samples submitted for diagnostic purposes which proved to be anti-complementary by complement fixation test, 49 were parvovirus B19 IgM positive. Forty four of the 49 serum samples were from patients with arthropathy. Acute parvovirus B19 infection should be suspected when a patient has symptoms of disease of the joints and the serum is anticomplementary.

Direct sample polymerase chain reaction for the detection of Mycoplasma pneumoniae: a simple system for clinical application

A semi-nested polymerase chain reaction system with primers derived from the P1 adhesin gene of Mycoplasma pneumoniae was evaluated for sensitivity and specificity for detection of M. pneumoniae. The method used target DNA within samples of M. pneumoniae broth cultures and clinical material, without a formal extraction process. The sensitivity for detection of DNA was found to be to a level of one copy per sample and was specific to M. pneumoniae only, discriminating from the other human mycoplasma and ureaplasma species tested. The system offers the opportunity for a simple and highly specific laboratory method for diagnosis which may be compared to currently available serological methods, and may provide another method of studying mycoplasma-induced pathology.

Genital mycoplasmas revisited--an evaluation of a new culture medium

The role of genital mycoplasmas as pathogens causing severe neonatal respiratory and central nervous system disease has been highlighted recently following publication of new data. These organisms are generally neglected by diagnostic laboratories in the United Kingdom, possibly due to the lack of a suitable commercially-available culture medium. We have evaluated the bioMerieux Mycoplasma-Lyo system using qualitative and quantitative studies and have found it to have suitable qualities and practical advantages for detection of Ureaplasma urealyticum and Mycoplasma hominis.

Detection of Chlamydia pneumoniae and Chlamydia psittaci in sputum samples by PCR

AIMS

To use the polymerase chain reaction (PCR) to detect Chlamydia pneumoniae and Chlamydia psittaci in sputum samples.

METHODS

A nested PCR was developed, the first stage of which amplified DNA from both C pneumoniae and C psittaci while the second stage targeted specifically at C pneumoniae, allowing the two species to be differentiated. The primers were designed not to amplify sequences from C trachomatis. A panel of 26 sputum samples from patients with community acquired pneumonia evaluated previously by enzyme linked immunosorbent assay (ELISA), direct immunofluorescence (DIF), and culture was tested blind by PCR. Most of these specimens also had accompanying serial serum samples which were tested for species specific antibodies using microimmunofluorescence (micro-IF).

RESULTS

PCR detected C pneumoniae DNA in 10 of the 26 samples and C psittaci DNA in four. There was good concordance between ELISA, DIF, micro-IF and PCR in the C pneumoniae group. Two of the C psittaci identified by PCR were labelled C pneumoniae by DIF but the PCR results were supported by serology or a history of bird contact. Of the PCR negative group: six were true negative results; two contained C trachomatis. There were four discrepant results.

CONCLUSIONS

The data suggest that PCR is effective in the detection of C pneumoniae. The sensitivity for C psittaci is inevitably lower due to the strategy taken but specificity seemed to be good.

The rapid serological diagnosis of infectious mononucleosis

A total of 121 samples of serum collected from 101 patients was tested to determine the sensitivity and specificity of a commercial latex agglutination test for detecting infectious mononucleosis heterophile antibody, a commercial immunofluorescence test for detecting antibody to Epstein-Barr virus capsid antigen and a rapid enzyme immunoassay for detecting antibody to Epstein-Barr virus nuclear antigen. Although the Epstein-Barr virus capsid antigen IgM indirect immunofluorescence test proved to be the most sensitive, false-positive reactions were seen when samples collected from patients with cytomegalovirus, hepatitis A virus, parvovirus and leptospira infection were tested. False-positive reactions were also seen with samples containing rheumatoid factor.

The differentiation of Chlamydia species by antigen detection in sputum specimens from patients with community-acquired acute respiratory infections

An amplified enzyme immunoassay (IDEIA III: Dako Diagnostics Ltd) for detecting genus-specific chlamydia antigen was evaluated prospectively on 286 respiratory specimens from 275 patients presenting with community-acquired pneumonia or persistent chest infection. Nineteen patients had evidence of recent chlamydial infection, having two or more positive sputum or serological markers. Sputa from two other patients were ELISA-positive in the absence of other positive criteria and were regarded as false-positive results. When compared with a direct immunofluorescence test for chlamydial elementary bodies (EBs) using a genus-specific monoclonal antibody, the ELISA gave a positive predictive value of 91% and a negative predictive value of 99%. Non-specific problems with a wide variety of other micro-organisms isolated from the sputa were not encountered. Attempts to differentiate between Chlamydia psittaci, Chlamydia pneumoniae and Chlamydia trachomatis using genus-specific lipopolysaccharide reactive--and species-specific major outer membrane protein--monoclonal antibodies were encouraging and results were substantiated, in most patients, by the species-specific serological assays of the whole-cell-inclusion immunofluorescence or micro-immunofluorescence assays. The study demonstrated that antigen detection techniques offer scope for routine laboratories to diagnose chlamydial respiratory infections rapidly and reliably and may enable differentiation to species level. Although immunofluorescence offers marginally greater sensitivity and specificity when compared with ELISA, the latter is less subjective and less demanding. Sixty-eight per cent of these infections would have remained undiagnosed despite the general availability of ELISA tests.

Clinical evaluation of enzyme immunoassay in rapid diagnosis of herpes simplex infections

AIMS

To evaluate the performance of antigen detection by IDEIA (NovoNordisk Ltd) in the rapid diagnosis of potentially serious herpes simplex (HSV) infections.

METHODS

Nine hundred and twelve specimens from a variety of clinical sites, including ocular, mucocutaneous, respiratory and genital material, urines and necropsy tissue, were compared by enzyme immunoassay (EIA) and conventional culture for the presence of HSV.

RESULTS

The EIA performed to a high level of sensitivity and specificity using a variety of specimen types. Some problems were encountered using cervical swabs from pregnant women and necropsy brain tissue. Analysis of clinical and contact history data of most patients giving discrepant results supported the evidence of recent HSV infection obtained by EIA. The mean culture time was 2.4 days (range one to eight days).

CONCLUSIONS

The HSV EIA test performed to a high level of sensitivity (93.7%) and specificity (96.6%) when compared with culture using a variety of clinical material. These results assumed cell culture was 100% sensitive and specific. The actual performance of the EIA test is probably much higher. This approach to rapid HSV diagnosis should be used more widely, particularly in potentially serious cases.

The limitations of IgM assays in the serological diagnosis of Mycoplasma pneumoniae infections

The most useful and reliable serological investigations for the diagnosis of current Mycoplasma pneumoniae infection, including reinfection, were investigated. Paired sera and respiratory specimens from 115 patients with lower respiratory tract symptoms were examined for evidence of current M. pneumoniae infection by serological response, as measured by complement-fixation and indirect immunofluorescence tests for specific IgM, IgA and IgG, and also by culture of M. pneumoniae from respiratory material. Specific IgM was not always detectable in cases where other criteria indicated current or recent infection. On the basis of the present results, it is postulated that primary infection and reinfection may be differentiated by the presence or absence of specific IgM in the presence of elevated specific IgA levels and, therefore, that estimation of both IgM and IgA is necessary for the maximal detection of current M. pneumoniae infection, including reinfections. Specific IgG levels remained elevated for many weeks and were not useful diagnostically.

Evaluation of Serodia Myco II particle agglutination test for detecting Mycoplasma pneumoniae antibody: comparison with mu-capture ELISA and indirect immunofluorescence

The Serodia Myco II particle agglutination test, which the manufacturers claim exclusively detects IgM antibody, was compared with two IgM-specific tests, a mu-capture ELISA, and indirect immunofluorescence for their ability to detect recent Mycoplasma pneumoniae infection. In general there was good agreement among the three tests, all three having similar sensitivity. One hundred and nine (78%) of serum samples gave concordant results in all three assays. Several sera gave positive particle agglutination titres, however, while being negative by the two other assays, and the Serodia Myco II test may not be as specific for detecting M pneumoniae IgM as the other two tests. While the Serodia Myco II test may be a good screening assay, it is unlikely to be a definitive test for M pneumoniae IgM, but may be better than the complement fixation test, particularly in younger patients in whom M pneumoniae IgM is found more frequently.

An investigation of the Mycoplasma pneumoniae infections in Cambridge in 1983 using mu-capture enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence (IF) and complement fixation (CF) tests

The mu-capture, the ELISA, IF and CF tests were used to study Mycoplasma pneumoniae infections in Cambridge in 1983. We studied 393 samples of serum submitted for investigation of M. pneumoniae infection, from 298 patients. There was a good correlation between mu-capture ELISA and IF for detecting M. pneumoniae-specific IgM, and between elevated CF titer, and the presence of M. pneumoniae-specific IgM. There was also a clear correlation between M. pneumoniae-specific IgM status and age. M. pneumoniae-specific IgM and IgA were most often found together in sera, but in some sera, only one of these antibodies was found at significant levels. These findings were not age related, and thus not obviously useful in differentiating primary and recurrent M. pneumoniae infections.

The clinical spectrum and diagnosis of Mycoplasma pneumoniae infection

The clinical, radiographic and microbiological data of 47 patients with Mycoplasma pneumoniae infection admitted to three Norfolk hospitals during a 20-month period between 1982 and 1983 have been reviewed. Thirty-nine presented with pneumonia and eight with non-pulmonary infection. The M. pneumoniae specific IgM test was positive in 42 of 45 patients tested (89 per cent); in 39 the levels were diagnostic on admission. Cold agglutinins were detected in 27 (57 per cent) and a fourfold rise in complement fixation titre was demonstrated in 13 (29 per cent). Sputum culture was positive in 12 (26 per cent). The extrapulmonary manifestations observed were haemolytic anaemia (17 per cent), Stevens Johnson syndrome (4.1 per cent), neurological abnormalities (4.1 per cent), arthritis (2.1 per cent), hepatitis (2.1 per cent) and pericarditis (2.1 per cent). One patient with multilobe pneumonia, pericardial effusion and haemolytic anaemia died. Six patients presented with a history of illness longer than a month; in three the clinical and radiographic picture suggested chronic disease (pulmonary tuberculosis, lymphoma and unresolving pneumonia). There were no distinctive clinical or radiographic features of M. pneumoniae infection. Diagnosis, therefore, relies on serological tests of which the most useful is the rapid, specific IgM test, positive in 86 per cent of the admission sera.

A micro-capture ELISA for detecting Mycoplasma pneumoniae IgM: comparison with indirect immunofluorescence and indirect ELISA

A mu-capture ELISA was developed for detecting Mycoplasma pneumoniae-specific IgM, and compared with an indirect immunofluorescent antibody (IFA) technique and an indirect ELISA. mu-capture ELISA and IFA compared well and were found to be the most sensitive assays. The IFA test can be completed in 2 h whilst the results of the mu-capture ELISA can be available in 24 h. Both tests are amenable to routine diagnostic use and have similar sensitivity. Indirect ELISA was found to be less sensitive and less specific, giving high assay values with several sera having undetectable M. pneumoniae CF antibody or CF antibody in low titre. Serum samples obtained from 11 patients at various times after M. pneumoniae infection showed maximum antibody levels within the first month by all assays, with a gradual fall in amount of IgM with time when assayed by mu-capture ELISA, a more gradual decline by IFA and hardly any decline with indirect ELISA. It was concluded that the indirect ELISA is unsuitable for the investigation of possible M. pneumoniae infection because the sustained high assay values with serum samples taken many months after infection, make interpretation of the test results very difficult.

Diagnosis of urethritis: role of polymorphonuclear leukocyte counts in gram-stained urethral smears

Polymorphonuclear leukocytes (PMNs) in the gram-stained urethral smears of 236 consecutive sexually active men without gonorrhea were analyzed quantitatively. The frequency distribution of the highest count of PMNs per high-power field (hpf) showed a count of four PMNs to be the "cut-off" point separating men with urethritis from those without urethritis. This cut-off point correlated well with the presence of Chlamydia trachomatis as well as with turbid urine. However, the PMN count in the gram-stained urethral smear was found to be more sensitive than the appearance of the urine in the diagnosis of urethritis among those with minimal symptoms and signs and not harboring C. trachomatis. This study also demonstrated a close similarity as regards clinical features and PMN count in gram-stained urethral smears between those harboring Ureaplasma urealyticum and those with no organisms.