Long-Term SARS-CoV-2 Antibody Seroprevalence in Blood Donors, Italy.

We evaluated SARS-CoV-2 antibody response in voluntary blood donors in Italy at different timepoints. Immediately after lockdown easing, 908/25,657 donors (3.5%) had low IgG titers against nucleocapsid. In the next 2 years, titers increased despite few COVID-19 symptoms. On multivariate analysis, allergic rhinitis was associated with reduced risk for symptomatic COVID-19.

Active Case Finding of Current Bornavirus Infections in Human Encephalitis Cases of Unknown Etiology, Germany, 2018-2020.

Human bornavirus encephalitis is a severe and often fatal infection caused by variegated squirrel bornavirus 1 (VSBV-1) and Borna disease virus 1 (BoDV-1). We conducted a prospective study of bornavirus etiology of encephalitis cases in Germany during 2018-2020 by using a serologic testing scheme applied along proposed graded case definitions for VSBV-1, BoDV-1, and unspecified bornavirus encephalitis. Of 103 encephalitis cases of unknown etiology, 4 bornavirus infections were detected serologically. One chronic case was caused by VSBV-1 after occupational-related contact of a person with exotic squirrels, and 3 acute cases were caused by BoDV-1 in virus-endemic areas. All 4 case-patients died. Bornavirus etiology could be confirmed by molecular methods. Serologic testing for these cases was virus specific, discriminatory, and a practical diagnostic option for living patients if no brain tissue samples are available. This testing should be guided by clinical and epidemiologic suspicions, such as residence in virus-endemic areas and animal exposure.

Human Outbreak of Trichinellosis Caused by Trichinella papuae Nematodes, Central Kampong Thom Province, Cambodia.

In September 2017, a severe trichinellosis outbreak occurred in Cambodia after persons consumed raw wild pig meat; 33 persons were infected and 8 died. We collected and analyzed the medical records for 25 patients. Clinical signs and symptoms included myalgia, facial or peripheral edema, asthenia, and fever. We observed increased levels of creatine phosphokinase and aspartate aminotransferase-, as well as eosinophilia. Histopathologic examination of muscle biopsy specimens showed nonencapsulated Trichinella larvae. A Trichinella excretory/secretory antigen ELISA identified Trichinella IgM and IgG. Biopsy samples were digested and larvae were isolated and counted. PCR for the 5S rDNA intergenic spacer region and a multiplex PCR, followed by sequencing identified the parasite as Trichinella papuae. This species was identified in Papua New Guinea during 1999 and in several outbreaks in humans in Thailand. Thus, we identified T. papuae nematodes in humans in Cambodia.

Rapid Screening Evaluation of SARS-CoV-2 IgG Assays Using Z-Scores to Standardize Results.

Many serologic tests are now available for measuring severe acute respiratory syndrome coronavirus 2 antibodies to evaluate potential protective immunity and for seroprevalence studies. We describe an approach to standardizing positivity thresholds and quantitative values for different assays that uses z-scores to enable rapid and efficient comparison of serologic test performance.

Encephalopathy and Encephalitis Associated with Cerebrospinal Fluid Cytokine Alterations and Coronavirus Disease, Atlanta, Georgia, USA, 2020.

There are few detailed investigations of neurologic complications in severe acute respiratory syndrome coronavirus 2 infection. We describe 3 patients with laboratory-confirmed coronavirus disease who had encephalopathy and encephalitis develop. Neuroimaging showed nonenhancing unilateral, bilateral, and midline changes not readily attributable to vascular causes. All 3 patients had increased cerebrospinal fluid (CSF) levels of anti-S1 IgM. One patient who died also had increased levels of anti-envelope protein IgM. CSF analysis also showed markedly increased levels of interleukin (IL)-6, IL-8, and IL-10, but severe acute respiratory syndrome coronavirus 2 was not identified in any CSF sample. These changes provide evidence of CSF periinfectious/postinfectious inflammatory changes during coronavirus disease with neurologic complications.

Severe Acute Respiratory Syndrome Coronavirus 2-Specific Antibody Responses in Coronavirus Disease Patients.

A new coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has recently emerged to cause a human pandemic. Although molecular diagnostic tests were rapidly developed, serologic assays are still lacking, yet urgently needed. Validated serologic assays are needed for contact tracing, identifying the viral reservoir, and epidemiologic studies. We developed serologic assays for detection of SARS-CoV-2 neutralizing, spike protein-specific, and nucleocapsid-specific antibodies. Using serum samples from patients with PCR-confirmed SARS-CoV-2 infections, other coronaviruses, or other respiratory pathogenic infections, we validated and tested various antigens in different in-house and commercial ELISAs. We demonstrated that most PCR-confirmed SARS-CoV-2-infected persons seroconverted by 2 weeks after disease onset. We found that commercial S1 IgG or IgA ELISAs were of lower specificity, and sensitivity varied between the 2 assays; the IgA ELISA showed higher sensitivity. Overall, the validated assays described can be instrumental for detection of SARS-CoV-2-specific antibodies for diagnostic, seroepidemiologic, and vaccine evaluation studies.

Bourbon Virus in Wild and Domestic Animals, Missouri, USA, 2012-2013.

Since its recent discovery, Bourbon virus has been isolated from a human and ticks. To assess exposure of potential vertebrate reservoirs, we assayed banked serum and plasma samples from wildlife and domestic animals in Missouri, USA, for Bourbon virus-neutralizing antibodies. We detected high seroprevalence in raccoons (50%) and white-tailed deer (86%).

Global Distribution of Human Protoparvoviruses.

Development of next-generation sequencing and metagenomics has revolutionized detection of novel viruses. Among these viruses are 3 human protoparvoviruses: bufavirus, tusavirus, and cutavirus. These viruses have been detected in feces of children with diarrhea. In addition, cutavirus has been detected in skin biopsy specimens of cutaneous T-cell lymphoma patients in France and in 1 melanoma patient in Denmark. We studied seroprevalences of IgG against bufavirus, tusavirus, and cutavirus in various populations (n = 840), and found a striking geographic difference in prevalence of bufavirus IgG. Although prevalence was low in adult populations in Finland (1.9%) and the United States (3.6%), bufavirus IgG was highly prevalent in populations in Iraq (84.8%), Iran (56.1%), and Kenya (72.3%). Conversely, cutavirus IgG showed evenly low prevalences (0%-5.6%) in all cohorts, and tusavirus IgG was not detected. These results provide new insights on the global distribution and endemic areas of protoparvoviruses.

Serologic Evidence of Scrub Typhus in the Peruvian Amazon.

Using a large, passive, febrile surveillance program in Iquitos, Peru, we retrospectively tested human blood specimens for scrub typhus group orientiae by ELISA, immunofluorescence assay, and PCR. Of 1,124 participants, 60 (5.3%) were seropositive, and 1 showed evidence of recent active infection. Our serologic data indicate that scrub typhus is present in the Peruvian Amazon.

Current Guidelines, Common Clinical Pitfalls, and Future Directions for Laboratory Diagnosis of Lyme Disease, United States.

In the United States, Lyme disease is caused by Borrelia burgdorferi and transmitted to humans by blacklegged ticks. Patients with an erythema migrans lesion and epidemiologic risk can receive a diagnosis without laboratory testing. For all other patients, laboratory testing is necessary to confirm the diagnosis, but proper interpretation depends on symptoms and timing of illness. The recommended laboratory test in the United States is 2-tiered serologic analysis consisting of an enzyme-linked immunoassay or immunofluorescence assay, followed by reflexive immunoblotting. Sensitivity of 2-tiered testing is low (30%-40%) during early infection while the antibody response is developing (window period). For disseminated Lyme disease, sensitivity is 70%-100%. Specificity is high (>95%) during all stages of disease. Use of other diagnostic tests for Lyme disease is limited. We review the rationale behind current US testing guidelines, appropriate use and interpretation of tests, and recent developments in Lyme disease diagnostics.

Antibodies against MERS coronavirus in dromedary camels, United Arab Emirates, 2003 and 2013.

Middle East respiratory syndrome coronavirus (MERS-CoV) has caused an ongoing outbreak of severe acute respiratory tract infection in humans in the Arabian Peninsula since 2012. Dromedary camels have been implicated as possible viral reservoirs. We used serologic assays to analyze 651 dromedary camel serum samples from the United Arab Emirates; 151 of 651 samples were obtained in 2003, well before onset of the current epidemic, and 500 serum samples were obtained in 2013. Recombinant spike protein-specific immunofluorescence and virus neutralization tests enabled clear discrimination between MERS-CoV and bovine CoV infections. Most (632/651, 97.1%) camels had antibodies against MERS-CoV. This result included all 151 serum samples obtained in 2003. Most (389/651, 59.8%) serum samples had MERS-CoV-neutralizing antibody titers >1,280. Dromedary camels from the United Arab Emirates were infected at high rates with MERS-CoV or a closely related, probably conspecific, virus long before the first human MERS cases.

Influenza A(H1N1)pdm09 virus infection in giant pandas, China.

We confirmed infection with influenza A(H1N1)pdm09 in giant pandas in China during 2009 by using virus isolation and serologic analysis methods. This finding extends the host range of influenza viruses and indicates a need for increased surveillance for and control of influenza viruses among giant pandas.

Interferon-gamma FlowSpot assay for the measurement of the T-cell response to cytomegalovirus.

Objectives: We describe a new method, FlowSpot, to assess CMV-specific T-cell response by quantification of interferon-gamma (IFN-γ). CMV-specific, T-cell-released IFN-γ was captured by flow beads and measured via flow cytometry. In the present study, we used FlowSpot to assess CMV-specific T-cell response in healthy individuals. The FlowSpot results were compared with those of serological analysis and enzyme-linked immunospot (ELISpot) assay. Methods: Experimental results and parameter analysis were investigated by using serological, ELISpot, and FlowSpot assays. Results: The levels of IFN-γ, which is released from CMV-specific T-cells, were measured, and the results and parameter analysis showed a good correlation between FlowSpot and ELISpot. However, FlowSpot was more sensitive and better reflected the strength of IFN-γ secretion than did ELISpot. Conclusions: Compared to ELISpot, FlowSpot has a high sensitivity and is cost and time effective. Thus, this method can be used in wider clinical and scientific applications.