Prevalence Of Positive Antibodies Research Articles

Micro-elimination of chronic hepatitis C virus in mental health settings: A prospective multicentre pragmatic trial.

Hepatitis C virus (HCV) prevalence is high in the mental health population. We sought to evaluate testing and treatment uptake for HCV following the implementation of a universal nurse led study in inpatient and outpatient mental health populations. From January 2018 to December 2020, we screened mental health inpatients (n = 322) and community mental health patients (n = 615) for HCV with either specialist hepatology nurses or mental health nurses (mental health nurse). 75.5% (464/615) of community patients and 100% (322/322) of inpatients consented to screening, with an HCV antibody-positive prevalence of 12.7% (59/464) in community patients and 19.6% (63/322) in inpatients. RNA detectable prevalence was 4.0% (22/464) and 7.5% (24/322), respectively. Community patients who were screened by specialist hepatology nurses were more likely to consent to screening (94.4% vs. 45.7%, p < 0.001) but had lower proportion of HCV antibody (10.5% vs. 20.3%, p < 0.001) and RNA detectable (4.0% vs. 7.5%, p = 0.018) when compared to mental health nurse screening. Engagement with treatment was 27.0% of community mental health patients and 45.8% of mental health inpatients undergoing treatment. All patients undergoing treatment and underwent sustained viral response (SVR) testing achieved SVR. Universal screening of HCV using a nurse-led model has high rates of success in mental health patients with high proportions undergoing screening, with no reduction in the rates of SVR achieved with DAA therapy compared to the general population. Further work is needed to bridge the gap between identification of HCV and treatment among mental health patients.

Occurrence of anti D alloantibodies among weak D and D negative patients.

Objective: To estimate the frequency of anti-D alloantibodies in patients with weak or negative D. Study Design: Cross-sectional study. Setting: Under CIP/IRB/1111 in the Blood Bank of CHUGHTAI Institute of Pathology. Period: May 2022 to October 2022. Material &amp; Methods: Patients who booked their blood group testing at this laboratory were tested for their ABO RH blood type. The EDTA and yellow top serum samples were taken from patients. Blood group was identified using tube method. Patients with Rh-D negative blood type and weak D were included in this study. Those patients were screened for alloantibodies by screening cell (Bio-Rad), and those patients whose screening came out positive were tested for antibody identification using an extended 11cell panel (Bio-Rad). The Statistics calculator was used to determine the sample size. Software SPSS version 23 was used to conduct all statistical analyses. Results: 14103 blood groups were tested. The age of patients on average was 51±22 years. The males and females were 44% and 56%, respectively. Out of n=14103, 9.5% came out Rh-negative blood type. The blood group distribution was as follows, B negative 46% O negative 23% A negative 20% AB negative 11%, and weak D 0.02% only. Total 7.1% participants with negative RH-D blood type had Rh alloantibodies detected. Patients with weak D had no Rh alloantibody. Conclusion: Blood group O RH-D negative was the most prevalent with positive anti D-alloantibodies. Prevalence of positive antibody was 7.1%.

Serology study of healthcare workers following a hospital-based outbreak of COVID-19 in North West Tasmania, Australia, 2020.

Healthcare facilities are high-risk settings for coronavirus disease 2019 (COVID-19) transmission. Early in the COVID-19 pandemic, the first large healthcare-associated outbreak within Australia occurred in Tasmania. Several operational research studies were conducted amongst workers from the implicated hospital campus, to learn more about COVID-19 transmission. Healthcare workers (HCWs) from the implicated hospital campus were invited to complete an online survey and participate in a serology study. Blood samples for serological testing were collected at approximately 12 weeks (round one) and eight months (round two) after the outbreak. A descriptive analysis was conducted of participant characteristics, serology results, and longevity of antibodies. There were 261 HCWs in round one, of whom 44 (17%) were polymerase chain reaction (PCR) confirmed outbreak cases; 129 of the 261 (49%) participated in round two, of whom 34 (27%) were outbreak cases. The prevalence of positive antibodies at round one was 15% (n = 38) and at round two was 12% (n = 15). There were 15 participants (12%) who were seropositive in both rounds, with a further 9% (n = 12) of round two participants having equivocal results after previously being seropositive. Six HCWs not identified as cases during the outbreak were seropositive in round one, with three still seropositive in round two. Of those who participated in both rounds, 68% (n = 88) were seronegative at both time points. Our findings demonstrate that serological testing after this large healthcare-associated COVID-19 outbreak complemented the findings of earlier diagnostic testing, with evidence of additional infections to those diagnosed when use of PCR testing had been restricted. The results also provide evidence of persisting SARS-CoV-2 antibody response eight months after an outbreak in an unvaccinated population. The high proportion of HCWs who remained seronegative is consistent with low community transmission in Tasmania after this outbreak.

Socioeconomic Disparities in SARS-CoV-2 Serology Testing in New York City

BACKGROUND AND AIM: There are uncertainties concerning the longevity of antibodies to SARS-CoV-2, with accurate assessment necessary for informing testing, vaccination efforts, and reopening plans. In New York City (NYC), disparities exist in SARS-CoV-2 testing and outcomes. Here, we characterize the spatial and temporal distribution of antibody test prevalence and antibody positive prevalence in NYC and investigate if antibody testing was disproportionately lower among socioeconomically vulnerable populations. METHODS: The number of antibody tests performed and the number of positive antibody tests were downloaded through December 10, 2020 from the NYC Coronavirus Data Repository. An index of socioeconomic status (SES) was created from Zip Code Tabulation Area level data downloaded from 2015-2019 American Community Survey 5-year estimates. The index includes median household income, median gross rent, percentage 150% poverty, proportion working class, civilian unemployment, 1 occupant per room, and an education measure. Spatial generalized linear mixed models accounting for random effects with a Besag-York-Mollie conditional autoregressive prior were performed to examine the association between SES and antibody testing and positivity. RESULTS:The distribution of antibody tests performed per 100,000 residents of ZCTA decreased over the study period, with the least tests performed in Staten Island (mean: 1014 tests, standard deviation: 304 tests) and the most testing performed in Queens (1180, 317). Antibody positive prevalence was consistently highest in the Bronx (26%, 1.0%), and lowest in Manhattan (16.4, 1.9) and Staten Island (15.0, 3.3). While increasing SES was not significantly associated with the number of antibody tests performed, increasing SES was associated with decreasing antibody positive prevalence. CONCLUSIONS:There is increased burden of COVID-19 disease on vulnerable communities, as well as potential gaps in providing appropriate resources and public health measures. Future efforts to characterize the impact of COVID-19 must utilize serologic data to understand the extent and impact of the disease in vulnerable communities. KEYWORDS: SARS-CoV-2, Antibody Testing, Disparities

447. COVID-19 Prevalence Among COVID-19 Exposed Health Care Workers at a Tertiary Care Center in San Bernardino County, Ca

BackgroundWe studied the prevalence of positive SARS-CoV2 antibody and positive SARS-CoV2 antigen among high risk health care workers at Loma Linda University Health System (LLUHS) who voluntarily obtained SARS-CoV2 antibody testing, and if indicated, antigen testing. The study determined that there is a significant decrease in the prevalence of SARS-CoV2 antigen among employees at LLUH compared to the community.MethodsEmployee Health and Occupational Medicine offered antibody testing to employees who were considered high risk, primarily working in the Coronavirus Disease 19 (COVID-19) designated units. We tested 658 subjects’ serum for the presence of IgM and IgG antibodies via the Nirmidas Qualitative SARS-CoV2 test. 29 subjects with a positive antibody test were subsequently tested for the presence of serum SARS-CoV2 antigen via PCR.ResultsThere were 31 subjects who tested positive for IgM or IgG antibodies. 11 subjects had positive IgM with negative IgG. 3 subjects had negative IgM with positive IgG. 15 patients had positive IgM and positive IgG. 2 subjects had positive IgM with negative IgG, were subsequently retested, and then found to have positive IgM and positive IgG.Of those 31 subjects with a positive antibody test, 2 were not tested for the COVID-19 antigen, 1 had an inconclusive test, 23 tested negative, and 5 tested positive. Of those 5 positive for the antigen, 2 had symptoms and 3 did not report symptoms or did not use the symptom questionnaire.The community prevalence of positive SARS-CoV2 antigen in San Bernardino is 0.37%, as of June 16. The prevalence of positive SARS-CoV2 antigen among LLUH employees is 0.03% and the prevalence of positive antibody is 0.18%. The value of z is -7.3206, p is < .00001. Thus, the result is significant at p < .01.ConclusionThe results of this testing supports the efficacy of the early protective measures that LLUHS implemented in preparation for the pandemic. Such protective measures include: mandated face masks, symptoms screening, testing for SARS-CoV2 antibody or antigen on patients admitted, a dedicated COVID-19 section of the emergency department as well as inpatient units, etc. Given the statistical significance of this study, the protective bundle can be used as a template for preventative measures for future pandemics.Disclosures All Authors: No reported disclosures

Thyroid antibodies levels in euthyroid men and women - residents of the Arctic Zone of the Russian Federation.

The aim of the study was to determine the levels of thyroid antibodies and their relationship with thyroid hormones and thyroglobulin in euthyroid men and women, residents of the Arctic zone of the Russian Federation. A total of 208 apparently healthy people were enrolled in this study and classified into two groups depending on gender and level of autoantibodies in the blood. Serum hormones of the pituitary-thyroid system, thyroglobulin and antibodies concentration was measured by enzyme immunoassay. The prevalence of positive antibodies among various examined groups was determined and the characteristics of euthyroid subjects with abnormal thyroid antibodies levels were studied. Circulating positive thyroid antibodies were found in 20% of the surveyed residents of the Arctic zone of the Russian Federation. The median serum antibodies against thyroid peroxidase (AntiTPO) or thyroglobulin (AntiTG) levels and the percentage of people in general population with positive antibodies (i.e. AntiTPO ≥ 50 IU / ml and / or AntiTG ≥ 100 IU / ml) were statistically significant higher in women than in men, p < 0.01. Such thyroid antibodies levels were associated with a higher thyroid gland functional activity in women, which was demonstrated by significantly higher thyroxin level and lower thyroglobulin value in the peripheral blood. Part of women positive for AntiTPO increased with age from 18 to 33% (in groups aged 18-44 and 45-59 years, p = 0.04). The findings of the study reveal correlation between thyroid function test and thyroid antibodies levels, elaborating the clinical importance of thyroid antibodies in clinical examination and follow-up of patients with autoimmune thyroid disorders.

Seroepidemiology of arbovirus in communities living under the influence of the lake of a hydroelectric dam in Brazil

Abstract Introduction The arbovirus proposes an important problem of public health in Brazil, especially in the Amazon, due to its capacity to cause outbreaks with high levels of morbidity-mortality in humans as well as in animals. Objective This paper had the objective to estimate the prevalence of antibodies to arbovirus in communities that live under the influence of the artificial lake of UHE Tucuruí in the State of Pará, Brazil. Method The analytical transversal study has selected 657 blood serum samples of individuals over 18, both genders, residents at the Sustainable Development Reserves (SDR) in the region of the lake of UHE Tucuruí. The epidemiological information has been registered in an instrument especially designed for such a study and the blood samples were collected in two periods of high and low tide of the lake. The blood serum tests were performed by the method of hemagglutination inhibition (HI). Results The results revealed a prevalence of positive antibodies to arbovirus of 85.0%, being 84.1% related to Flavivirus (vaccine strain of YFV), 25.5% related to Alphavirus and 34.6% to Bunyavirus. The results of serum prevalence to arbovirus between the periods of high tide and low tide have revealed significance amongst the Alphavirus, not observed in the other families. Conclusion In general, the data from this paper have suggested that the anthropoid actions on the environment of the lake have become determinant factors for the prevalence of arboviral antibodies.

Bovine viral diarrhea virus (BVDV) infection in dairy cattle herds in northeast Thailand.

Bovine viral diarrhea virus causes a wide range of clinical manifestation with subsequent economic losses in dairy production worldwide. Our study of a population of dairy cattle in Thailand based on 933 bulk tank milk samples from nine public milk collection centers aimed to monitor infective status and to evaluate the effect of the infection in cows as well as to examine the reproductive performance of heifers to provide effective recommendations for disease control in Thailand. The results showed a moderate antibody-positive prevalence in the herd (62.5%), with the proportion of class-3 herd, actively infected stage, being 17.3%. Fourteen persistently infected (PI) animals were identified among 1196 young animals from the class-3 herds. Most of the identified PI animals, 11/14, were born in one sub-area where bovine viral diarrhea virus (BVDV) investigation has not been performed to date. With respect to reproductive performance, class-3 herds also showed higher median values of reproductive indices than those of class-0 herds. Cows and heifers in class-3 herds had higher odds ratio of calving interval (CI) and age at first service (AFS) above the median, respectively, compared to class-0 herds (OR = 1.29; P = 0.02 and OR = 1.63; P = 0.02). Our study showed that PI animals were still in the area that was previously studied. Furthermore, a newly studied area had a high prevalence of BVDV infection and the infection affected the reproductive performance of cows and heifers. Although 37.5% of the population was free of BVDV, the lack of official disease prevention and less awareness of herd biosecurity may have resulted in continuing viral spread and silent economic losses have potentially occurred due to BVDV. We found that BVDV is still circulating in the region and, hence, a national control program is required.

Seroprevalence ofToxoplasma gondiiInfection in Fattening Pigs in Northeast China

Seroprevalence of Toxoplasma gondii infection in fattening pigs in Heilongjiang Province, northeast China, was investigated between July 2011 and June 2012. In total, 1,014 pig serum samples were collected from 10 administrative regions and assayed for T. gondii antibodies by indirect hemagglutination (IHA) test using a commercially available kit. The average T. gondii antibody-positive prevalence was 4.6% (47/1,014), which is relatively lower than that in other provinces in China. Seroprevalence in fattening pigs raised on small farms (6.3%) was significantly higher than that on large farms (3.8%) (P < 0.05), and the seroprevalence ranged from 2.4% (Shuangyashan) to 6.8% (Qitaihe) between different geographical regions. Given that pork is not examined for T. gondii infection in China by law, these findings have public health implications and provide useful baseline information for the control of pig toxoplasmosis in this unique region of China.

The frequency of RBC alloantibodies in Chinese surgical patients

ObjectiveThe aim of this study was to evaluate the frequency of red blood cells (RBC) alloantibodies in surgical patients. Materials and methodsEighteen thousands nine hundred and eighty blood samples of Chinese patients who were undergoing surgery were collected and tested between January 2009 and September 2010. For patients with RBC alloantibodies, the sequences of antibodies were identified with the Diamed Asia antibody screen system. Data on gender, age, transfusion history, pregnancy history, and alloantibody specificity were collected. ResultsThirty-nine alloantibodies were identified from 18,980 samples. The prevalence of positive antibodies was 0.21%. The most frequently identified alloantibody was a RH system antibody (66.7%) (26/39) including: anti-E (16/39), anti-c (5/39), anti-cE (2/39), anti-e, anti-Cw, and anti-D (1/39 respectively). Other antibodies included anti-M (5/39), anti-Lea (2/39), and anti-Leb (1/39), anti-K+S (1/39), anti-Jka (1/39), and anti-Jsa (1/39). The frequency of alloantibodies in females was greater than that in males (31 vs 8). ConclusionThe results show a higher predominance of RBC alloantibodies in females than males. Anti-E is the most common alloantibody identified in the Chinese surgical population and is also more frequent in females compared to males.

Seroprevalence of Antibodies againstAnisakis simplexLarvae among Health-Examined Residents in Three Hospitals of Southern Parts of Korea

The present study was performed to estimate the seroprevalence of larval Anisakis simplex infection among the residents health-examined in 3 hospitals in southern parts of Korea. A total of 498 serum samples (1 serum per person) were collected in 3 hospitals in Busan Metropolitan city, Masan city, and Geoje city in Gyeongsangnam-do (Province) and were examined by IgE-ELISA and IgE-western blotting with larval A. simplex crude extract and excretory-secretory products (ESP). The prevalence of antibody positivity was 5.0% and 6.6% with ELISA against crude extracts and ESP, respectively. It was also revealed that infection occurred throughout all age groups and higher in females than in males. A specific protein band of 130 kDa was detected from 10 patients with western blot analysis against crude extract and ESP among those who showed positive results by ELISA. Our study showed for the first time the seroprevalence of anisakiasis in Korea. The allergen of 130 kDa can be a candidate for serologic diagnosis of anisakiasis.

Seroprevalence of Toxoplasma Gondii in Pigs From Southern China

The seroprevalence of toxoplasmosis in pigs was examined in China's southern Guangdong Province from March 2008 through May 2009. A total of 1,022 serum samples was collected from 12 administrative cities and assayed for Toxoplasma gondii antibodies by enzyme-linked immunosorbent assay test. The seroprevalence ranged from 0 to 58.1% and the average T. gondii antibody-positive prevalence was 27.0% (276/1,022), with breeding boars having the highest level at 39.6% (38/96) followed by breeding sows at 36.9% (52/141). The results of the present survey indicate that T. gondii infection is a significant health problem in pigs and represents a public health concern in southern China.

Serum carbonic anhydrase autoantibodies in metabolic syndrome

Aims Carbonic anhydrase (CA) autoantibodies have been observed in various autoimmune and idiopathic diseases right now. The aim of this study was to investigate the presence of anti-carbonic anhydrase I and II antibodies in subjects with metabolic syndrome (MetS). Methods 43 subjects with MetS and 30 non-MetS subjects (controls) were included in the study. Carbonic anhydrase autoantibodies were screened by ELISA. Results Anti-CA I antibody was detected in 7 of 43 subjects with MetS. The antibody-positive prevalence of MetS group (16%) was found to be significantly higher compared with that of control group ( p < 0.05). There were no significant changes in positive rate of anti-CA II antibody. Positive results were obtained in 2 of 43 subjects with MetS. Conclusions Anti-CA I antibodies were present in sera obtained from MetS subject and these antibodies may be involved in pathogenesis of MetS.

Screening for Associated Autoimmunity in Children and Adolescents with Type 1 Diabetes Mellitus (T1DM)

Background/Aims: Type 1 diabetes (T1DM) is associated with autoimmune thyroid, celiac, autoimmune gastric and Addison’s disease. Our aim was to investigate the prevalence of associated autoantibodies in relation to the demographic and β-cell autoantibody status (anti-GAD). Methods: Antibodies against thyroid peroxidase (anti-TPO), thyroglobulin (anti-Tg), tissue transglutaminase (anti-tTG IgA), parietal cells (APCA) and adrenal tissue (AAA) were measured in 144 children with T1DM with a mean ± SD age of 12.3 ± 4.6 years and a diabetes duration of 4.6 ± 3.8 years. Results: The prevalence of antibody positivity among our patients was: anti-GAD 53.2%, anti-thyroid (anti-TPO 17.4%, anti-Tg 11.1%); anti-tTG IgA 7.6%, APCA 4.0%, and AAA 0%. Among the children with positive anti-thyroid antibodies, 60% developed autoimmune thyroiditis, while among those anti-tTG IgA positive, 62.5% developed biopsy-confirmed celiac disease. Female gender was more frequent among anti-tTG IgA-positive patients (OR 4.47, p = 0.068), while increasing age was associated with anti-Tg positivity (OR 22.9, p = 0.041). The presence of anti-thyroid antibodies was associated with the presence of anti-GAD (OR 1.45, p = 0.01) and parietal cell antibodies (OR 4.98, p = 0.09). Conclusion: Among T1DM patients, the prevalence rates of anti-thyroid and parietal cell antibodies increased with age and diabetes duration. As the presence of anti-GAD was associated with gastric and thyroid autoimmunity, it could serve as marker for the development of additional autoimmunity in adolescents with diabetes.

Evaluation of IgG-ELISA for the diagnosis of Schistosoma japonicum in a high prevalence, low intensity endemic area of China

Antibody-based diagnostic methods for detecting infection with Schistosoma japonicum have been developed and integrated into the national control program in China; however, the utility of these methods compared with conventional coprological methods remains unclear. In two consecutive years, we compared the performance characteristics of Kato–Katz with a commercially available enzyme-linked immunosorbent assay (ELISA) that detects anti-egg antigen IgG antibodies in a high prevalence, low intensity village in China (1025 subjects in 2005 and 652 subjects in 2006). In comparison with Kato–Katz based on duplicate stool specimens, each read in triplicate, the sensitivity of IgG-ELISA was high, ranging from 79.3% to 87.4% but with a relatively low specificity of 38.9% to 53.5%. The positive predictive value ranged from 20.8% to 24.6% while the negative predictive value ranged from 93.1% to 94.4%. When analyzed as continuous variables, there was a poor correlation between EPG (eggs per gram feces) and antibody level in both years ( r 2005 = 0.23 and r 2006 = 0.41). We detected a trend toward reduced sensitivity at lower infection intensity as measured by Kato–Katz in 2005 ( P = 0.262) and 2006 ( P = 0.287). We evaluated changes in antibody levels and the prevalence of positive antibody in the cohort of subjects examined in both 2005 and 2006 ( n = 565). The prevalence of positive antibody but not the continuous antibody level, decreased in individuals who were uninfected at both time points or who transitioned from infected to uninfected as assessed by Kato–Katz. In this cohort, the distribution of antibody levels measured in 2006 among individuals who were positive by Kato–Katz in 2006 broadly overlapped with the distribution of antibody levels in individuals who were negative by Kato–Katz in both 2005 and 2006. Our results indicate fairly poor performance characteristics of the anti-egg antigen IgG-ELISA for the detection of active infection with S. japonicum in our community based sample and are in contrast with other reports based on more selected populations. The high prevalence but low intensity of S. japonicum in our study community reflects the evolving epidemiology of schistosomiasis in communities receiving intermittent treatment with praziquantel in China. We suggest marked caution in implementing anti-egg antigen IgG-ELISA based diagnosis for either individual level diagnosis or population-based targeting for national control programs.

Hepatitis C in Schizophrenia: Screening Experience in a Community-Dwelling Clozapine Cohort

Hepatitis C virus (HCV) infection occurs in up to 20% of patients with chronic mental illnesses. To determine the prevalence of hepatitis C in a diagnostically well-defined sample, the authors screened all schizophrenia outpatients in a clozapine clinic (N=98) for HCV antibodies. Eight patients were positive for hepatitis C antibodies (antibody-positive prevalence: 8.2%); of those, 50% had detectable viral loads (viremia-positive prevalence: 4.1%). Screening for HCV infection should be considered for outpatients with schizophrenia. However, clinical experience treating HCV in schizophrenia patients is limited; in this cohort, 2 years after screening, no patient had received interferon/ribavirin treatment.

Prevalence and risk factor analysis of TTV infection in prostitutes.

TTV, a DNA virus, has been isolated from patients with non-A to non-E post-transfusion hepatitis. In the past it was assumed that TTV was transmitted parenterally. It is unclear whether sexual contact leads to transmission of this virus. In this study, two sets of TTV-specific polymerase chain reaction primers were used to detect serum TTV DNA in 140 prostitutes and 136 controls. The prevalence of TTV DNA in prostitutes was significantly higher than in the control group (46/140 [32.9%] vs. 29/136 [21.3%]; P = 0.043). There was no significant difference in the prevalence of positive antibody to hepatitis A virus (anti-HAV) in either group (87.8% for prostitutes, 85.3% for controls). No particular risk factor was significantly associated with positive TTV DNA in prostitutes. In summary, TTV is highly prevalent in prostitutes. Transmission of TTV via sexual contact is not as efficient as transmission of hepatitis C and D viruses and GB virus-C hepatitis G virus. The high prevalence of TTV in controls indicates that there are diverse routes of transmission of this virus.

Prevalence of nonthyroid specific autoantibodies in autoimmune thyroid diseases.

To clarify the involvement of polyclonal activation of autoimmune reaction in organ-specific autoimmune diseases, we investigated the prevalence of nonthyroid specific autoantibodies in 50 patients with autoimmune thyroid diseases (22 patients with Graves' disease and 28 with Hashimoto's disease) and in 50 age- and sex-matched controls. None of the 100 subjects had any clinical manifestations or laboratory data indicating any other immunological, infectious, hepatic, or malignant diseases. The prevalence of positive antibodies to nucleus, smooth muscle, and single-stranded DNA in the patients (26%, 36%, and 34%, respectively) was higher than that in the control group (8%, 4%, and 4%, respectively), although neither group was positive for autoantibodies against double-stranded DNA, extractable nuclear antigen, SS-A, SS-B, mitochondria, or rheumatoid factor. Furthermore, 66% of the patients had at least one autoantibody to nucleus, smooth muscle, or single-stranded DNA. In conclusion, patients with autoimmune thyroid diseases show high prevalence of autoantibody against not only thyroid-specific, but also nonthyroid-specific antigens. These results are consistent with the concept that immune reaction of patients with organ-specific autoimmune diseases may be polyclonally accelerated to the production of antibodies against both organ and nonorgan specific autoantigens.

High Prevalence of Positive Antibodies to Legionella pneumophila among Outpatients

A serologic survey of antibodies to Legionella pneumophila serogroups 1 through 6 was performed to assess the prevalence of positive antibody titers among outpatients and to evaluate the association between elevated antibody titers and previously identified risk factors for legionellosis. Subjects were recruited from outpatient clinics at the Minneapolis VA Medical Center. Each participant completed a self-administered questionnaire which asked about their general health and any recent symptoms of illness. Medical records were also audited for all participants to provide additional information on medical history and known risk factors for Legionella infection. Single samples of serum were obtained from each subject, and antibody titers to L pneumophila serogroups 1 through 6 were assayed. Three hundred ninety-six subjects were enrolled in the study. They had a mean age of 67 years, and 98 percent were male subjects. Overall, 36 percent of the subjects had positive antibody titers (greater than or equal to 1:128) to L pneumophila. There were no differences between those with and without elevated titers with respect to recent systemic symptoms or other previously established risk factors for legionellosis. We conclude that positive anti-Legionella antibodies are a frequent occurrence among these outpatients. This has important implications for the interpretation of single or static antibody titers from patients who are acutely ill.