Comparative evaluation of assays for IgM detection of rubella and measles infections.

BACKGROUND: Serological diagnosis of infections due to measles and rubella viruses is done by IgM detection. The aim of this study was to comparatively evaluate commercial systems for detecting IgM against both viruses, including those of ELISA, in indirect and capture formats, chemiluminescence and electrochemiluminescence. METHODS: Seven (for rubella) and six (for measles) assays were studied. One hundred and sixty two samples were included in the study (from 90 rubella and 72 measles cases), and all were analyzed in all the assays. RESULTS: The ranges of sensitivity, specificity and agreement for rubella were 94.8-100%, 52.4-100% and 75.5-98.1%, respectively. The corresponding ranges for measles assays were 87.0-100%, 53.3-100%, and 73.0-99.4%. CONCLUSION: The best-performing assays were chemiluminescence (for measles and rubella IgM), and electrochemiluminescence (for rubella IgM).

Comparative evaluation of assays for IgM detection of rubella and measles infections / Evaluación comparativa de ensayos para la detección de IgM en infecciones por rubéola y sarampión

BackgroundSerological diagnosis of infections due to measles and rubella viruses is done by IgM detection. The aim of this study was to comparatively evaluate commercial systems for detecting IgM against both viruses, including those of ELISA, in indirect and capture formats, chemiluminescence and electrochemiluminescence.MethodsSeven (for rubella) and six (for measles) assays were studied. One hundred and sixty two samples were included in the study (from 90 rubella and 72 measles cases), and all were analyzed in all the assays.ResultsThe ranges of sensitivity, specificity and agreement for rubella were 94.8–100%, 52.4–100% and 75.5–98.1%, respectively. The corresponding ranges for measles assays were 87.0–100%, 53.3–100%, and 73.0–99.4%.ConclusionThe best-performing assays were chemiluminescence (for measles and rubella IgM), and electrochemiluminescence (for rubella IgM).

El diagnóstico serológico de las infecciones por los virus de la rubéola y del sarampión se realiza por detección de IgM específica. El objetivo de este estudio fue evaluar comparativamente sistemas comerciales para la detección de IgM frente a ambos virus, incluyendo ensayos de ELISA, tanto con metodologías indirectas como de captura, así como quimioluminiscencia y electroquimioluminiscencia.MétodosSe estudiaron 7 ensayos para rubéola y 6 para sarampión. Se emplearon 162 muestras (de 90 casos de rubéola y de 72 de sarampión) que se analizaron en todos los ensayos.ResultadosLos rangos de sensibilidad, especificidad y concordancia para los ensayos de rubéola fueron 94,8-100%, 52,4-100% y 75,5-98,1%, respectivamente. Los rangos correspondientes para los ensayos de sarampión fueron 87-100%, 53,3-100% y 73-99,4%, respectivamente.ConclusiónLos mejores ensayos fueron quimioluminiscencia (para IgM frente a rubéola y a sarampión) y electroquimioluminiscencia (para IgM frente a rubéola).

Measles in Vaccinated People: Epidemiology and Challenges in Surveillance and Diagnosis in the Post-Elimination Phase. Spain, 2014-2020.

The MMR vaccination program was introduced in Spain in 1981. Consistently high vaccination coverage has led to Spain being declared free of endemic measles transmission since 2014. A few imported and import-related cases were reported during the post-elimination phase (2014 to 2020), with very low incidence: three cases per million of inhabitants a year, 70% in adults. In the post-elimination phase an increasing proportion of measles appeared in two-dose vaccinated individuals (up to 14%), posing a challenge to surveillance and laboratory investigations. Severity and clinical presentation were milder among the vaccinated. The IgM response varied and the viral load decreased, making the virus more difficult to detect. A valid set of samples (serum, urine and throat swab) is strongly recommended for accurate case classification. One third of measles in fully vaccinated people was contracted in healthcare settings, mainly in doctors and nurses, consistent with the important role of high intensity exposure in measles breakthrough cases. Surveillance protocols and laboratory algorithms should be adapted in advanced elimination settings. Reinforcing the immunity of people working in high exposure environments, such as healthcare settings, and implementing additional infection control measures, such as masking and social distancing, are becoming crucial for the global aim of measles eradication.

Phlebovirus-associated diseases transmitted by phlebotominae in Spain: Are we at risk?

The genera Phlebovirus transmitted by Diptera belonging to the Psychodidae family are a cause of self-limited febrile syndrome in the Mediterranean basin in summer and autumn. Toscana virus can also cause meningitis and meningoencephalitis. In Spain, Toscana, Granada, Naples, Sicily, Arbia and Arrabida-like viruses have been detected. The almost widespread distribution of Phlebotomus genus vectors, and especially Phlebotomus perniciosus, in which several of these viruses have been detected, makes it very likely that there will be regular human infections in our country, with this risk considered moderate for Toscana virus and low for the other ones, in areas with the highest vector activity. Most of the infections would be undiagnosed, while only Toscana virus would have a greater impact due to the potential severity of the illness.

Fatal Case of Crimean-Congo Hemorrhagic Fever Caused by Reassortant Virus, Spain, 2018.

In August 2018, a fatal autochthonous case of Crimean-Congo hemorrhagic fever was confirmed in western Spain. The complete sequence of the viral genome revealed circulation of a new virus because the genotype differs from that of the virus responsible for another case in 2016. Practitioners should be alert to possible new cases.

Zika virus infection in pregnant travellers and impact on childhood neurodevelopment in the first two years of life: A prospective observational study.

BACKGROUND: The emergence of Zika virus (ZIKV) represents a threat with consequences on maternal and children's health. We aimed to assess the clinical and epidemiological characteristics of pregnant women returning from ZIKV affected areas, and the effects of maternal ZIKV infection on birth outcomes and children's health. METHODS: This was a hospital-based prospective observational study conducted at the Hospital Clínic of Barcelona and Hospital Sant Joan de Déu, Barcelona, Spain, from January 2016 to February 2020. RESULTS: One hundred and ninety-five pregnant women who had travelled to ZIKV affected areas during pregnancy were recruited. Four women (2.1%) had a confirmed ZIKV infection, 40 women (20.5%) a probable infection, and 151 (77.4%) were negative for ZIKV. Among the ZIKV confirmed cases, a pregnant woman suffered a miscarriage, highly plausible to be associated with ZIKV infection. Brain cysts and microcalcifications were detected in 7% of fetuses or infants from women with confirmed or probable ZIKV infection. Neurodevelopmental delay in the language function was found in 33.3% out of the 21 children evaluated. CONCLUSIONS: These findings contribute to the understanding of ZIKV prevalence estimates, and the impact of maternal ZIKV infection on pregnancy outcomes and children's health. Results highlight the importance of long-term surveillance in pregnant travellers and their children.

Identification of Immunological Parameters as Predictive Biomarkers of Relapse in Patients with Chronic Myeloid Leukemia on Treatment-Free Remission.

BCR-ABL is an aberrant tyrosine kinase responsible for chronic myeloid leukemia (CML). Tyrosine kinase inhibitors (TKIs) induce a potent antileukemic response mostly based on the inhibition of BCR-ABL, but they also increase the activity of Natural Killer (NK) and CD8+ T cells. After several years, patients may interrupt treatment due to sustained, deep molecular response. By unknown reasons, half of the patients relapse during treatment interruption, whereas others maintain a potent control of the residual leukemic cells for several years. In this study, several immunological parameters related to sustained antileukemic control were analyzed. According to our results, the features more related to poor antileukemic control were as follows: low levels of cytotoxic cells such as NK, (Natural Killer T) NKT and CD8±TCRγß+ T cells; low expression of activating receptors on the surface of NK and NKT cells; impaired synthesis of proinflammatory cytokines or proteases from NK cells; and HLA-E*0103 homozygosis and KIR haplotype BX. A Random Forest algorithm predicted 90% of the accuracy for the classification of CML patients in groups of relapse or non-relapse according to these parameters. Consequently, these features may be useful as biomarkers predictive of CML relapse in patients that are candidates to initiate treatment discontinuation.

Absence of IgG antibodies among high-risk contacts of two confirmed cases of Crimean-Congo haemorrhagic fever in the autonomous region of Madrid (Spain).

Crimean-Congo haemorrhagic fever (CCHF) is a widely distributed tick-borne disease. In Spain, the disease has emerged as outbreak associated with high-risk exposures. Our goal was to evaluate the prevalence of antibodies against the CCHF virus (CCHFV) in high-risk contacts. A cross-sectional study was conducted. Three hundred eighty-six high-risk contacts were identified comprising family contacts and hospital workers who had attended the cases. Fifty-seven cases with closer exposure were selected. However, forty-nine cases participated in the study. IgG antibodies were detected by immunoenzymatic techniques. All determinations tested negative for anti-CCHFV IgG antibodies. Most of the responders were women (73.5%), and belong to the intensive care department (53.1%). In relation to other possible sources of exposures, 18.4% travelled to countries with CCHF transmission risk. No CCHF positivity was recorded among selected high-risk contacts. This highlights the importance of standard precautions which might have protected healthcare workers and care providers from CCHF infection.

Cytotoxic cell populations developed during treatment with tyrosine kinase inhibitors protect autologous CD4+ T cells from HIV-1 infection.

Tyrosine kinase inhibitors (TKIs) are successfully used in clinic to treat chronic myeloid leukemia (CML). Our group previously described that CD4+ T cells from patients with CML on treatment with TKIs such as dasatinib were resistant to HIV-1 infection ex vivo. The main mechanism for this antiviral activity was primarily based on the inhibition of SAMHD1 phosphorylation, which preserves the activity against HIV-1 of this innate immune factor. Approximately 50% CML patients who achieved a deep molecular response (DMR) may safely withdraw TKI treatment without molecular recurrence. Therefore, it has been speculated that TKIs may induce a potent antileukemic response that is maintained in most patients even one year after treatment interruption (TI). Subsequent to in vitro T-cell activation, we observed that SAMHD1 was phosphorylated in CD4+ T cells from CML patients who withdrew TKI treatment more than one year earlier, which indicated that these cells were now susceptible to HIV-1 infection. Importantly, these patients were seronegative for HIV-1 and seropositive for cytomegalovirus (CMV), but without CMV viremia. Although activated CD4+ T cells from CML patients on TI were apparently permissive to HIV-1 infection ex vivo, the frequency of proviral integration was reduced more than 12-fold on average when these cells were infected ex vivo in comparison with cells isolated from untreated, healthy donors. This reduced susceptibility to infection could be related to an enhanced NK-dependent cytotoxic activity, which was increased 8-fold on average when CD4+ T cells were infected ex vivo with HIV-1 in the presence of autologous NK cells. Enhanced cytotoxic activity was also observed in CD8 + T cells from these patients, which showed 8-fold increased expression of TCRγδ and more than 18-fold increased production of IFNγ upon activation with CMV peptides. In conclusion, treatment with TKIs induced a potent antileukemic response that may also have antiviral effects against HIV-1 and CMV, suggesting that transient use of TKIs in HIV-infected patients could develop a sustained antiviral response that would potentially interfere with HIV-1 reservoir dynamics.

Comparative evaluation of assays for IgM detection of rubella and measles infections.

BACKGROUND: Serological diagnosis of infections due to measles and rubella viruses is done by IgM detection. The aim of this study was to comparatively evaluate commercial systems for detecting IgM against both viruses, including those of ELISA, in indirect and capture formats, chemiluminescence and electrochemiluminescence. METHODS: Seven (for rubella) and six (for measles) assays were studied. One hundred and sixty two samples were included in the study (from 90 rubella and 72 measles cases), and all were analyzed in all the assays. RESULTS: The ranges of sensitivity, specificity and agreement for rubella were 94.8-100%, 52.4-100% and 75.5-98.1%, respectively. The corresponding ranges for measles assays were 87.0-100%, 53.3-100%, and 73.0-99.4%. CONCLUSION: The best-performing assays were chemiluminescence (for measles and rubella IgM), and electrochemiluminescence (for rubella IgM).

Clinical Outcomes of a Zika Virus Mother-Child Pair Cohort in Spain.

BACKGROUND: Zika virus (ZIKV) infection has been associated with congenital microcephaly and other neurodevelopmental abnormalities. There is little published research on the effect of maternal ZIKV infection in a non-endemic European region. We aimed to describe the outcomes of pregnant travelers diagnosed as ZIKV-infected in Spain, and their exposed children. METHODS: This prospective observational cohort study of nine referral hospitals enrolled pregnant women (PW) who travelled to endemic areas during their pregnancy or the two previous months, or those whose sexual partners visited endemic areas in the previous 6 months. Infants of ZIKV-infected mothers were followed for about two years. RESULTS: ZIKV infection was diagnosed in 163 PW; 112 (70%) were asymptomatic and 24 (14.7%) were confirmed cases. Among 143 infants, 14 (9.8%) had adverse outcomes during follow-up; three had a congenital Zika syndrome (CZS), and 11 other potential Zika-related outcomes. The overall incidence of CZS was 2.1% (95%CI: 0.4-6.0%), but among infants born to ZIKV-confirmed mothers, this increased to 15.8% (95%CI: 3.4-39.6%). CONCLUSIONS: A nearly 10% overall risk of neurologic and hearing adverse outcomes was found in ZIKV-exposed children born to a ZIKV-infected traveler PW. Longer-term follow-up of these children is needed to assess whether there are any later-onset manifestations.

Imported Human West Nile Virus Lineage 2 Infection in Spain: Neurological and Gastrointestinal Complications.

We report the first human case of West Nile virus (WNV) lineage 2 infection imported to Spain by a traveler returning from Romania. Serum, cerebrospinal fluid and urine samples were analyzed and West Nile virus infection was identified by PCR and serological tests. The patient developed fever, diarrhea and neurological symptoms, accompanied by mild pancreatitis, described previously in very few cases as a complication of WNV infection and by alithiasic cholecystitis. Viral RNA was detected in urine until 30 days after the onset of symptoms and neutralizing antibodies were detected at very low titers. The phylogenetic analysis in a fragment of the NS5 gene of the virus showed a homology with sequences from WNV lineage 2 belonging to the monophyletic Central/Southern European group.

Evaluation of the LIAISON XL Zika Capture IgM II for the Diagnosis of Zika Virus Infections.

The aim of this study is to evaluate the performance characteristics of the LIAISON XL Zika Capture IgM II. For this purpose we tested 128 samples obtained from recent infections caused by the Zika (ZIKV; 74 samples), dengue (DENV; 10 samples), chikungunya (CHIK V; 11 samples), rubella (RUBV; 10 samples) and measles (MeV; 10 samples) viruses, as well as human parvovirus B19 (HPVB19; 13 samples). The results of the assay under evaluation are compared with those obtained from an indirect immunofluorescence (IIF) assay, and the discrepancies are resolved by considering other laboratory results (PCR and a plaque-reduction neutralization test). The LIAISON showed excellent sensitivity (100%). The specificity (91.25%) was hampered by some false-positive results in recent dengue virus, chikungunya virus, measles virus and human parvovirus B19 infections. The method evaluated is adequate, but the low specificity makes it necessary to consider the clinical and epidemiological contexts of patients, as well as other laboratory results.

Hantavirus Pulmonary Syndrome in Traveler Returning from Nepal to Spain.

Most human hantavirus infections occur in Asia, but some cases have been described in Europe in travelers returning from Asia. We describe a case of hantavirus pulmonary syndrome in a previously healthy traveler occurring shortly after he returned to Spain from Nepal. Serologic tests suggested a Puumala virus-like infection.

Characteristics of Zika virus infection among international travelers: A prospective study from a Spanish referral unit.

BACKGROUND: From the first Zika virus (ZIKV) description, it has progressively widespread worldwide. We analyzed demographic, clinical, microbiologic and travel-related characteristic from returned patients from a ZIKV endemic country in a referral Tropical Medicine Unit. METHOD: A prospective cohort study performed in a Spanish referral center with the aim of determining the significant factors associated with confirmed Zika virus (ZIKV) infection. RESULTS: 817 patients, (56% women, median age 36 [IQR, Interquartile Range: 32-42]) were enrolled. Most had returned from Latin America (n = 486; 59.4%), travelled for tourism (n = 404; 49.4%) and stayed a median of 18 days (IQR: 10-30). 602 (73.6%) presented symptoms, but only 25 (4%) were finally diagnosed with confirmed ZIKV infection (including two pregnant women, without adverse fetal outcomes), 88% (n:22) presented with fever and 92% (n:23) with rash. 56% (n:14) arthralgia and/or myalgia and 28% (n:7) conjunctivitis. The presence of conjunctivitis, fever and rash were associated with an 8.9 (95% CI: 2.2-34.9), 6.4 (95% CI: 1.2-33.3) and 72.3 (95% CI: 9.2-563.5) times greater probability of confirmed ZIKV infection, respectively. CONCLUSION: Travel characteristics and clinical presentation may help clinicians to optimize requests for microbiological testing. Diagnosis of arboviriasis in travellers arriving form endemic areas remains a challenge for clinicians, but must be detected for the possible transmission outside endemic areas, where the vector is present.

Secukinumab does not impair the immunogenic response to the influenza vaccine in patients.

Objective: To evaluate whether immunological response to influenza vaccination is impaired in patients who are receiving secukinumab. Patients and methods: Subjects suffering from psoriatic arthritis or ankylosing spondylitis who were receiving treatment with secukinumab and healthy volunteers were included.All participants received seasonal inactivated trivalent influenza vaccine recommended by the WHO in the 2017-2018 northern hemisphere influenza season, which contained an A/Michigan/45/2015 (H1N1)pdm09-like virus, an A/Hong Kong/4801/2014 (H3N2)-like virus and a B/Brisbane/60/2008-like virus.Haemagglutination inhibition was used to evaluate basal antibody (Ab) titres against the three influenza vaccine virus strains just before vaccination and at least 4 weeks after the vaccine administration. Response to vaccine was considered as >4-fold increases in Ab titre. Results: Thirty subjects, 17 patients and 13 healthy controls, with a follow-up duration of 33±8 days, were analysed. There were no demographic differences between groups. Patients and controls achieved a median of 4.6-fold and 4.0-fold increases, respectively, for anti H1N1 and almost 4.0 (3.7) for patients and 5.3 for controls for anti-B Ab. Both groups presented a poor response against H3N2, with <1.5-fold increase. Seroconversion rates were similar in both groups. Secukinumab did not influence the response to the influenza vaccine (relative risk: 1.09 (95% CI 0.58 to 2.07) for H1N1, RR: 1.53 (95% CI 0.15 to 15.0) for H3N2 and RR: 0.72 (95% CI 0.32 to 1.83) for B strain). Conclusion: In our study, secukinumab has no effect on the immunogenic response to the influenza vaccine.

Duration of immunity to measles, rubella and mumps during the first year of life.

INTRODUCTION AND OBJECTIVES: The MMR vaccine was included in the official vaccination schedule in Spain in 1981. Currently, most women of childbearing age are vaccinated and have not been naturally infected. Several studies have shown that vaccinated women have a lower antibody concentration than that achieved after natural infection, and a shorter duration of transplacentally acquired antibodies in their children. The objective of this study was to determine the antibody titer in mothers and their infants at birth and throughout the first year of life under current epidemiological circumstances. MATERIAL AND METHODS: Single-center, observational, descriptive and prospective study conducted between October 2013 and December 2014. One sample of serum and another of a dried blood spot on filter paper were taken from each mother. Dried blood spot samples on filter paper were taken from the children at birth, and at 3, 6, 9 and 12 months. In all the samples, levels of antibodies to the measles, rubella and mumps viruses were measured using standardized quantitative assays. RESULTS: 146 mother-child pairs were included. 78.4%, 86.9% and 67.1% of mothers had antibodies to measles, rubella and mumps, respectively. A decrease in the antibody titer in children was observed after 3 months, and no antibodies against the three diseases were detected by the age of 6 months. Comparisons revealed no statistically significant differences between the antibody titers of children of mothers born before or after 1981 during the first year of their life. DISCUSSION: The rapid loss of transplacentally acquired antibodies against measles, rubella and mumps, under current epidemiological conditions, suggests that bringing the MMR vaccination forward to 9 months might be justified. Larger population studies are needed to confirm these results.

The Application and Interpretation of IgG Avidity and IgA ELISA Tests to Characterize Zika Virus Infections.

In the absence of viremia, the diagnostics of Zika virus (ZIKV) infections must rely on serological techniques. In order to improve the serological diagnosis of ZIKV, ZIKV-IgA and ZIKV-IgG avidity assays were evaluated. Forty patients returning from ZIKV endemic areas, with confirmed or suspected ZIKV infections were studied. Samples were classified as early acute, acute and late acute according to the number of days post illness onset. Low avidity IgG was only detected at acute and late acute stages and IgA mostly at the early acute and acute stages. The date of sampling provides useful information and can help to choose the best technique to use at a determined moment in time and to interpret low avidity IgG and IgA results, improving the serological diagnosis of ZIKV.