Characterizing hepatitis B virus infection in children in the Democratic Republic of Congo to inform elimination efforts.

Objective: Despite global reductions in hepatitis B virus (HBV) prevalence, an estimated 6.2 million children are infected, two-thirds of whom live in the WHO Africa region. We sought to characterize childhood HBV to inform elimination efforts in the Democratic Republic of Congo (DRC), one of the largest and most populous African countries. Methods: Using the most recent (2013-14) nationally representative Demographic and Health Survey in the DRC, we analyzed HBV surface antigen (HBsAg) on dried blood spots and associated survey data from children aged 6-59 months. We estimated HBsAg-positivity prevalence nationally, regionally, and by potential correlates of infection. We evaluated spatial variation in HBsAg-positivity prevalence, overall and by age, sex, and vaccination status. Findings: Using data from 5,679 children, we found national HBsAg-positivity prevalence was 1.3% (95% CI: 0.9%-1.7%), but ranged from 0.0% in DRC's capital city province, Kinshasa, to 5.6% in northwestern Sud-Ubangi Province. Prevalence among boys (1.8%, 95% CI: 1.2%-2.7%) was double that among girls (0.7%, 95%CI: 0.4%-1.3%). Tetanus antibody-negativity, rurality, and lower household wealth were also significantly associated with higher HBsAg-positivity prevalence. We observed no difference in prevalence by age. Children had higher HBsAg-positivity odds if living with ≥1 HBsAg-positive adult household member (OR: 2.3, 95%CI: 0.7-7.8), particularly an HBsAg-positive mother (OR: 7.2, 95%CI:1.6-32.2). Conclusion: In the largest national survey of HBV among children and household contacts in the DRC, we found that childhood HBV prevalence was 10-60 times the global target of 0.1%. We highlight specific regions and populations for further investigation and focused prevention efforts.

The clinical impact of maternal COVID-19 on mothers, their infants, and placentas with an analysis of vertical transfer of maternal SARS-CoV-2-specific IgG antibodies.

INTRODUCTION: The effect of SARS-CoV-2 severity or the trimester of infection in pregnant mothers, placentas, and infants is not fully understood. METHODS: A retrospective, observational cohort study in Chapel Hill, NC of 115 mothers with SARS-CoV-2 and singleton pregnancies from December 1, 2019 to May 31, 2021 via chart review to document the infants' weight, length, head circumference, survival, congenital abnormalities, hearing loss, maternal complications, and placental pathology classified by the Amsterdam criteria. RESULTS: Of the 115 mothers, 85.2% were asymptomatic (n = 37) or had mild (n = 61) symptoms, 13.0% had moderate (n = 9) or severe (n = 6) COVID-19, and 1.74% (n = 2) did not have symptoms recorded. Moderate and severe maternal infections were associated with increased C-section, premature delivery, infant NICU admission, and were more likely to occur in Type 1 (p = 0.0055) and Type 2 (p = 0.0285) diabetic mothers. Only one infant (0.870%) became infected with SARS-CoV-2, which was not via the placenta. Most placentas (n = 63, 54.8%) did not show specific histologic findings; however, a subset showed mild maternal vascular malperfusion (n = 26, 22.6%) and/or mild microscopic ascending intrauterine infection (n = 28, 24.3%). The infants had no identifiable congenital abnormalities, and all infants and mothers survived. DISCUSSION: Most mothers and their infants had a routine clinical course; however, moderate and severe COVID-19 maternal infections were associated with pregnancy complications and premature delivery. Mothers with pre-existing, non-gestational diabetes were at greatest risk of developing moderate or severe COVID-19. The placental injury patterns of maternal vascular malperfusion and/or microscopic ascending intrauterine infection were not associated with maternal COVID-19 severity.

Comparison of a lysed whole blood method to purified cell preparations for lymphocyte immunophenotyping: differences between healthy controls and HIV-positive specimens.

Although the majority of clinical laboratories now use a lysed whole blood (LWB) method for routine immunophenotyping, researchers wishing to perform other types of studies with lymphocytes from HIV+ patients may still need to use purified cell preparations, such as peripheral blood mononuclear cells (PBMC). A comparison study of the two methods was performed, using peripheral blood specimens from normal donors and from patients infected with the human immunodeficiency virus (HIV+). Reproducibility studies and several types of holding studies (both before and after specimen processing) were also performed. The results suggest that the two different methods of sample preparation have different effects upon abnormal patient specimens than those observed in healthy controls. Immunophenotyping results derived from the two different methods cannot be considered equivalent for the purposes of quantitating the presence of a particular type of cell.

Diagnostic usefulness of antineutrophil cytoplasmic autoantibody serology. Comparative evaluation of commercial indirect fluorescent antibody kits and enzyme immunoassay kits.

Antineutrophil cytoplasmic autoantibodies (ANCAs) are increasingly used as serologic markers for pauci-immune crescentic glomerulonephritis and small vessel vasculitis. Many hospital laboratories and referral laboratories use commercial assay kits to detect ANCAs, despite inadequate documentation in the medical literature of kit performance. We evaluated the diagnostic sensitivity, specificity, and predictive value of 3 commercial indirect immunofluorescence assay (IFA) kits and 7 commercial enzyme immunoassay (EIA) kits for several ANCA subtypes. Serum samples from 396 patients with a variety of renal diseases were analyzed, including 146 patients with pauci-immune crescentic glomerulo-nephritis with or without systemic vasculitis. With 1 exception, the kits had more than 90% agreement with the reference standard and gave results similar to those of research laboratories. IFA diagnostic sensitivity ranged from 81% to 91% and EIA sensitivity from 75% to 84%. Maximum specificity was obtained with combined IFA and EIA. Diagnostic specificity was more than 70% for 2 of 3 IFA kits and at least 90% for 5 of 7 EIA kits. Predictive values varied with clinical manifestations. Most commercial IFA and EIA kits that were evaluated provide acceptably accurate analytic results.

Selective screening for chlamydial infection: which criteria to use?

BACKGROUND: Screening sexually active women for Chlamydia trachomatis is necessary to detect asymptomatic infections. Selective screening is a common strategy because universal screening is too costly in many settings. In order to guide local programs in the choice of selective screening criteria, we examined the performance of previously proposed screening criteria for C. trachomatis. METHODS: A clinic-based, cross-sectional study was conducted in public family planning and sexually transmitted disease (STD) clinics in ten counties in North Carolina. Women (n = 4471 in family planning and n = 2201 in STD clinics) undergoing pelvic examination were enrolled consecutively. Nine sets of screening criteria, including age alone, were compared using sensitivity, specificity, number of tests required and receiver-operator characteristic (ROC) analysis. All women underwent testing with ligase chain reaction assay of cervical specimens to identify C trachomatis infection. RESULTS: The prevalence of C. trachomatis was 7.8% and 11.0% in family planning and STD clinics, respectively. The sensitivities of published criteria ranged from 0.50 to 0.97. Specificities ranged from 0.05 to 0.66. In family planning clinics, the best performing criteria would detect 84% of infections while screening 51% of women. In STD clinics, the same criteria would detect 83% of infections but require testing 67% of women. Testing women aged < or =22 would detect 77% of infections in family planning and 74% of infections in STD clinics, while testing 51% and 48% of the women, respectively. CONCLUSIONS: When site-specific criteria cannot be developed, age alone is an acceptable strategy for selective screening for chlamydial infection.

Genital ulcer disease. Management in the HIV era.

What are the main causes of genital ulcer disease in the United States? Why is clinical diagnosis so difficult? What role will molecular diagnostics have in the future? The authors answer these questions and provide a functional approach to successful management of three common types of sexually transmitted genital ulcers.

Isolated donor specific alloantibody-mediated rejection after ABO compatible liver transplantation.

Antibody-mediated rejection (AMR) after liver transplantation is recognized in ABO incompatible and xeno-transplantation, but its role after ABO compatible liver transplantation is controversial. We report a case of ABO compatible liver transplantation that demonstrated clinical, serological and histological signs of AMR without evidence of concurrent acute cellular rejection. AMR with persistently high titers of circulating donor specific antibodies resulted in graft injury with initial centrilobular hepatocyte necrosis, fibroedematous portal expansion mimicking biliary tract outflow obstruction, ultimately resulting in extensive bridging fibrosis. Immunofluorescence microscopy demonstrated persistent, diffuse linear C4d deposits along sinusoids and central veins. Despite intense therapeutic intervention including plasmapheresis, IVIG and rituximab, AMR led to graft failure. We present evidence that an antibody-mediated alloresponse to an ABO compatible liver graft can cause significant graft injury independent of acute cellular rejection. AMR shows distinct histologic changes including a characteristic staining profile for C4d.

Evaluation of the Rheuma-Lex latex agglutination test for detection of rheumatoid factor.

The performance of the Trinity Laboratories Rheuma-Lex latex agglutination test kit for detection of Rheumatoid factor (RF) in patient sera was evaluated. The method and test results of the Rheuma-Lex test were compared to those obtained with another commercially available latex agglutination test kit (RapiTex RF Test) on 162 sera submitted for RF testing. Discrepant results were resolved by testing those sera with a third commercially available kit. The Rheuma-Lex and the RapiTex kits demonstrated sensitivities of 100 and 87%, specificities of 98 and 99%, negative predictive values of 100 and 97%, positive predictive values of 94 and 94% and efficiencies of 99 and 97% respectively. The Rheuma-Lex test kit was judged to be a sensitive, reliable and simple assay for RF detection in serum.

Comparison of seven commercial kits for detection of antibodies to Borrelia burgdorferi.

Five enzyme immunoassay (EIA) and two Western blot (WB) commercial kits were compared for their ability to detect antibodies to Borrelia burgdorferi. The panel of 53 test sera consisted of 25 sera positive for antibodies to Borrelia burgdorferi, 15 sera negative for such antibodies, 5 sera reactive in serologic tests for syphilis, and 8 sera containing antinuclear antibodies and/or rheumatoid factor. The rate of agreement with reference results was 93%, 90%, 90% and 88% for EIA kits from Diamedix, Cambridge Biotech, Mardx and Sigma respectively. The sensitivity and specificity was 84% and 100% respectively for Cambridge Biotech, 76% and 94% for Diamedix, 68% and 83% for Mardx, and 68% and 83% for Sigma. The three confirmatory tests, Cambridge Biotech WB, General Biometrics P39 EIA and Mardx WB, demonstrated 75%, 60% and 63% agreement respectively. The sensitivity and specificity was 52% and 100% respectively for Cambridge Biotech WB, 24% and 100% for General Biometrics P39 EIA, and 44% and 100% for Mardx WB. The results demonstrate the variable performance of commercial serologic kits for detection of antibodies to Borrelia burgdorferi. WB appears to be a better confirmatory test than the single protein EIA.

Induction of lyme arthritis in LSH hamsters.

In studies of experimental Lyme disease, a major obstacle has been the unavailability of a suitable animal model. We found that irradiated LSH/Ss Lak hamsters developed arthritis after injection of Borrelia burgdorferi in the hind paws. When nonirradiated hamsters were injected in the hind paws with B. burgdorferi, acute transient synovitis was present. A diffuse neutrophilic infiltrate involved the synovia and periarticular structures. The inflammation was associated with edema, hyperemia, and granulation tissue. Numerous spirochetes were seen in the synovial and subsynovial tissues. The histopathologic changes were enhanced in irradiated hamsters. The onset and duration of the induced swelling were dependent on the dose of radiation and the inoculum of spirochetes. Inoculation of irradiated hamsters with Formalin-killed spirochetes or medium in which B. burgdorferi had grown for 7 days failed to induce swelling. This animal model should prove useful for studies of the immune response to B. burgdorferi and the pathogenesis of Lyme arthritis.

Passive immunization prevents induction of Lyme arthritis in LSH hamsters.

We determined that sera obtained from hamsters infected with Borrelia burgdorferi could prevent the induction of Lyme arthritis. When irradiated hamsters were administered immune serum and subsequently challenged with B. burgdorferi, no evidence of infection was detected. Recipients failed to develop swelling of the hind paws, and no histopathologic changes were detected. In addition, B. burgdorferi was not recovered from tissues of hamsters that were passively immunized. By contrast, irradiated hamsters that were administered normal hamster serum or saline and infected with the Lyme spirochete developed arthritis. Extensive histopathologic changes occurred in the hind paws and knee joints, and spirochetes were recovered from most of the tissues examined. These results show that immune serum can confer complete protection on recipient hamsters to challenge with B. burgdorferi.

The pathologist's view of Lyme disease.

Lyme disease is a multisystem disease caused by the spirochete Borrelia burgdorferi and is transmitted to humans primarily through Ixodid ticks. The clinical spectrum of the disease is continuing to expand while in its wake the pathology and histopathologic manifestations are being uncovered. We review the pathology of Lyme disease in man beginning with the tick bite. We present the pathologic changes of the rash, erythema migrans, as well as the neurologic, cardiac, and arthritic changes of the disease. We can expand our understanding of the immunobiology of Lyme disease by studying the interactions of B. burgdorferi in an experimental animal model.

Histopathology of Lyme arthritis in LSH hamsters.

The authors studied the histopathologic evolution of arthritis in nonirradiated and irradiated hamsters infected with Borrelia burgdorferi. Nonirradiated hamsters injected in the hind paws with B. burgdorferi developed an acute inflammatory reaction involving the synovium, periarticular soft tissues, and dermis. This acute inflammatory reaction was short-lived and was replaced by a mild chronic synovitis as the number of detectable spirochetes in the synovium, periarticular soft tissues, and perineurovascular areas diminished. Exposing hamsters to radiation before inoculation with B. burgdorferi exacerbated and prolonged the acute inflammatory phase. Spirochetes also persisted longer in the periarticular soft tissues. A major histopathologic finding was destructive and erosive bone changes of the hind paws, which resulted in deformation of the joints. These studies should be helpful in defining the immune mechanism participating in the onset, progression, and resolution of Lyme arthritis.

Beta interferon inhibits Toxoplasma gondii growth in human monocyte-derived macrophages.

Gamma interferon (IFN-gamma) previously has been shown to block the replication of Toxoplasma gondii in fibroblasts by the induction of indoleamine 2,3-dioxygenase (IDO) activity. IFN-beta also is known to induce IDO activity in monocyte-derived macrophages, but its ability to block the growth of T. gondii has not been demonstrated. We found not only that the combination of IFN-beta and lipopolysaccharide induced greater IDO activity in monocyte-derived macrophages than did IFN-beta alone but that this combination also was effective in inhibiting the growth of T. gondii. In addition, the inhibition was reversed by the addition of exogenous tryptophan, thus demonstrating that a mechanism by which IFN-beta inhibited T. gondii replication was by the induction of IDO.

Depletion of complement and effects on passive transfer of resistance to infection with Borrelia burgdorferi.

When irradiated hamsters are passively immunized with immune serum before challenge with Borrelia burgdorferi, they are completely protected from arthritis and infection. The complement dependency of this protection was addressed by treating hamsters with cobra venom factor. Depletion of complement abrogated the ability of immune serum obtained 1 and 10 weeks after infection to confer complete protection. By contrast, depletion of complement had no effect on the ability of 3-week immune serum to confer protection. These results suggest that complement-dependent, and possibly complement-independent, antibodies are important for preventing the induction of Lyme arthritis.

Intensity discrimination as a function of stimulus level with electric stimulation.

Difference limens (DLs) for changes in electric current were measured from multiple electrodes in each of eight cochlear-implanted subjects. Stimuli were 200-microseconds/phase biphasic pulse trains delivered at 125 Hz in 300-ms bursts. DLs were measured with an adaptive three-alternative forced-choice procedure. Fixed-level psychometric functions were also obtained in four subjects to validate the adaptive DLs. Relative intensity DLs, specified as Weber fractions in decibels [10 log (delta I/I)] for standards above absolute threshold, decreased as a power function of stimulus intensity relative to absolute threshold [delta I/I = beta (I/I0) alpha] in the same manner as Weber fractions for normal acoustic stimulation reported in previous studies. Exponents (alpha) of the power function for electric stimulation ranged from -0.4 to -3.2, on average, an order of magnitude larger than exponents for acoustic stimulation, which range from -0.07 to -0.11. Normalization of stimulus intensity to the dynamic range of hearing resulted in Weber functions with similar negative slopes for electric and acoustic stimulation, corresponding to an 8-dB average improvement in Weber fractions across the dynamic range. Sensitivity to intensity change ¿10 log beta¿ varied from -0.42 to -13.5 dB compared to +0.60 to -3.34 dB for acoustic stimulation, but on average was better with electric stimulation than with acoustic stimulation. Psychometric functions for intensity discrimination yielded Weber fractions consistent with adaptive procedures and d' was a linear function of delta I. Variability among repeated Weber-fraction estimates was constant across dynamic range. Relatively constant Weber fractions across all or part of the dynamic range, observed in some subjects, were traced to the intensity resolution limits of individual implanted receiver/stimulators. DLs could not be accurately described by constant amplitude changes, expressed as a percentage of dynamic range ¿delta A(% DR)¿. Weber fractions from prelingually deafened subjects were no better or worse than those from postlingually deafened subjects. The cumulative number of discriminable intensity steps across the dynamic range of electric hearing ranged from as few as 6.6 to as many as 45.2. Physiologic factors that may determine important features of electric intensity discrimination are discussed in the context of a simple, qualitative, rate-based model. These factors include the lack of compressive cochlear preprocessing, the relative steepness of neural rate-intensity functions, and individual differences in patterns of neural survival.

Determination of natural killer cell function by flow cytometry.

Natural killer cells (NK cells) are a subset of peripheral blood lymphocytes that mediate non-major histocompatibility complex-restricted cytotoxicity of foreign target cells. The "gold standard" assay for NK cell activity has been the chromium release assay. This method is not easily performed in the clinical laboratory because of difficulties with disposal of radioactive and hazardous materials, short reagent half-lives, expense, and difficulties with assay standardization. We describe a flow cytometric assay for the clinical measurement of NK cell activity. This study compared the chromium release assay and the flow cytometric assay by using clinically relevant specimens. There were no significant differences between the two assays in the measurement of lytic activity for 17 peripheral blood specimens or in reproducibility in repeated samplings of healthy individuals. We also established a normal range of values for NK activity in healthy adults and identified a small cluster of individuals who have exceptionally high or low levels of NK activity. The flow cytometric assay was validated by testing specimens from subjects expected to have abnormally low levels of NK activity (pregnant women) and specimens from healthy individuals in whom the activity of NK cells was enhanced by exposure to interleukin-2 or alpha interferon. Treatment with these agents was associated with a significant increase in NK activity. These results confirm and extend those of others, showing that the flow cytometric assay is a viable alternative to the chromium release assay for measuring NK cell activity.

Laboratory diagnosis of congenital syphilis by immunoglobulin M (IgM) and IgA immunoblotting.

We screened cord blood or serum samples from 101 infants at risk for congenital syphilis and serum samples from their mothers for immunoglobulin G (IgG), IgM, and IgA antibodies to Treponema pallidum by western blotting (immunoblotting). Clinical evaluation showed that six infants had signs and/or symptoms consistent with congenital syphilis. The sera from five of these infants were IgM blot positive, and four were IgA blot positive. Four asymptomatic infants had serologic evidence of congenital syphilis. The sera from three of these infants were IgM blot positive, and two were IgA blot positive. However, the IgM reactivity of the serum from one asymptomatic infant, which was also IgA positive, was abolished by protein G treatment. An IgM capture enzyme-linked immunosorbent assay corroborated the presence of IgM antibodies in six of seven IgM blot-reactive sera. Overall, for detection of symptomatic congenital syphilis, a sensitivity of 83% for IgM blotting and 67% for IgA blotting was obtained. The significance of positive IgM or IgA Western blots for asymptomatic infants requires further study to confirm infection in these infants.

Comparison of the effects of Ficoll-Hypaque separation and whole blood lysis on results of immunophenotypic analysis of blood and bone marrow samples from patients with hematologic malignancies.

We compared flow cytometric immunophenotyping results obtained by using the lysed whole blood method of sample preparation with those obtained by using Ficoll-Hypaque-separated cells on 44 consecutive specimens from patients with various hematologic malignancies. When the samples were analyzed as a group, seven antigens (CD2, CD3, CD5, CD11c, CD20, CD22, and CD34) demonstrated significantly different percentages of positively staining cells. When the samples were grouped by disease, results for patients with acute lymphocytic leukemia were discordant for CD22 and HLA-DR and results for patients with hairy cell leukemia were discordant for CD34. Most of the differences, however, were not with antigens critical to the evaluation of the malignancy. Additionally, the most frequent reason for differences in the percentage of positive cells was due to isotype control-based placement of the quadrant markers and not an actual discrepancy in staining. However, analysis of the CD34 antigen yielded eight instances in which staining of Ficoll-Hypaque-separated cells was essentially negative, but a clearly positive population was evident with the lysed preparation. This finding has important implications because of the prognostic significance of this antigen. Further studies are needed to determine the cause of this phenomenon.

Immunoglobulin G2 confers protection against Borrelia burgdorferi infection in LSH hamsters.

We showed that immune serum and its immunoglobulin fractions, specifically immunoglobulin G2 (IgG2), could confer complete protection to irradiated hamsters challenged with the Lyme disease spirochete. Immune serum and its immunoglobulin fractions also killed Borrelia burgdorferi in vitro. Depletion of complement in vivo abrogated the ability of IgG2 to confer complete protection against B. burgdorferi. Furthermore, the majority of antibody reactivity directed against B. burgdorferi was found in the IgG2 fraction. These findings demonstrate that IgG2 plays an important role in acquired resistance against infection with B. burgdorferi. Additional studies are needed to determine the mechanism(s) by which B. burgdorferi evades host defenses despite the development of an effective borreliacidal antibody response.