Abstract Background Since their emergence in the Americas, chikungunya (CHIKV) and Zika (ZIKV) viruses co-circulate with dengue virus (DENV), hampering clinical diagnosis. We investigated clinical and epidemiological characteristics of arboviral infections during the introduction and spread of CHIKV and ZIKV through northeastern Brazil. Methods Surveillance for arboviral diseases among febrile patients was performed at an emergency health unit of Salvador, Brazil, between September 2014 and July 2016. We interviewed patients to collect data on symptoms, reviewed medical records to obtain the presumptive diagnoses, and performed molecular and serological testing to confirm DENV, CHIKV, ZIKV, or nonspecific flavivirus (FLAV) diagnosis. Results Of 948 participants, 247 (26.1%) had an acute infection, of which 224 (23.6%) were single infections (DENV, 32 [3.4%]; CHIKV, 159 [16.7%]; ZIKV, 13 [1.4%]; and FLAV, 20 [2.1%]) and 23 (2.4%) coinfections (DENV/CHIKV, 13 [1.4%]; CHIKV/FLAV, 9 [0.9%]; and DENV/ZIKV, 1 [0.1%]). An additional 133 (14.0%) patients had serological evidence for a recent arboviral infection. Patients with ZIKV presented with rash and pruritus (69.2% each) more frequently than those with DENV (37.5% and 31.2%, respectively) and CHIKV (22.9% and 14.7%, respectively) (P < .001 for both comparisons). Conversely, arthralgia was more common in CHIKV (94.9%) and FLAV/CHIKV (100.0%) than in DENV (59.4%) and ZIKV (53.8%) (P < .001). A correct presumptive clinical diagnosis was made for 9%–23% of the confirmed patients. Conclusions Arboviral infections are frequent causes of febrile illness. Coinfections are not rare events during periods of intense, concomitant arboviral transmission. Given the challenge to clinically distinguish these infections, there is an urgent need for rapid, point-of-care, multiplex diagnostics.

Zika virus (ZIKV), a flavivirus, and chikungunya virus (CHIKV), an alphavirus, are infectious RNA arboviruses transmitted to humans by the bite of Aedes species mosquitoes. Both viruses have only recently emerged in the Western Hemisphere (1, 2), and along with dengue virus (DENV), another flavivirus, now circulate widely in Brazil. The acute illness caused by these viruses, characterized by fever, rash, myalgia, arthralgia, and conjunctivitis, is nonspecific, and differential diagnosis on the basis of clinical findings alone is challenging. Later infectious sequelae include chronic arthritis for CHIKV (2) and encephalitis, immune-mediated syndromes, and stroke for DENV (3). Recently, the association between ZIKV infection and severe fetal complications such as microcephaly in pregnant women has been established (4), and the virus has also been linked to neurological complications such as Guillain-Barré syndrome (5). Thus, broadbased assays are needed for differential diagnosis of vectorborne febrile illnesses and to identify potential coinfections. Here we report the utility of metagenomic next-generation sequencing (mNGS) as a screening tool to identify coinfections and the use of genome recovery and phylogenetic analyses directly from patient serum samples in the context of the ongoing ZIKV outbreak. We also show that the clinical presentation of arboviral coinfections seems to favor the virus present at a higher titer in acutely infected individuals. MATERIALS AND METHODSZIKV serum sample collection, ZIKV RT-PCR, and DENV antibody testing. Written consent from patients was obtained under a study protocol approved by the Brazil Ministry of Health (Certificado de Apresentação para Apreciação Ética 45483115.0.0000.0046, no. 1159.184, Brazil). Serum samples were obtained from 15 patients seen at Aliança Hospital in Salvador, Bahia, Brazil, from April 2015 to January 2016 who were given a presumptive diagnosis of an acute viral illness by emergency department physicians and were found to be positive by qualitative reverse transcription-PCR (RT-PCR) testing for ZIKV. Serum samples Bahia01 to Bahia15 were subjected to RNA extraction using the QIAamp viral RNA minikit (Qiagen), and RNA was reverse transcribed using the Superscript II reverse transcriptase kit (Invitrogen), followed by qualitative RT-PCR testing for ZIKV using primers targeting the NS5 gene (6). Serum samples were also tested for DENV infection using an enzyme-linked immunosorbent assay (ELISA) specific for the NS1 antigen and anti-DENV IgG/IgM according to the manufacturer's instructions (Dengue Duo Test; Bioeasy Diagnostica, Brazil).Metagenomic next-generation sequencing. A separate serum aliquot was extracted for total nucleic acid using the Qiagen viral RNA minikit (Qiagen), followed by DNase treatment using a cocktail of Turbo DNase (Thermo Fisher Scientific) and Baseline-Zero DNase (Epicentre Biotechnologies), followed by NGS library construction using the NexteraXT kit (Illumina) as previously described (7,8). Runs of single-end, 160-base pair...

Background: There is growing concern about individuals reported to suffer repeat COVID-19 disease episodes, these in a small number of cases characterised as de novo infections with distinct sequences, indicative of insufficient protective immunity even in the short term. Methods: Observational case series and case-control studies reporting 33 cases of recurrent, symptomatic, qRT-PCR positive COVID-19. Recurrent disease was defined as symptomatic recurrence after symptom-free clinical recovery, with release from isolation > 14 days from the beginning of symptoms confirmed by qRT-PCR. The case control study-design compared this group of patients with a control group of 62 patients randomly selected from the same COVID-19 database. Results: Of 33 recurrent COVID-19 patients, 26 were female and 30 were HCW. Mean time to recurrence was 50.5 days which was associated with being a HCW (OR 36.4 (p < 0.0 0 01)), and blood type A (OR 4.8 (p = 0.002)). SARS-CoV-2 antibodies were signifcantly lower in recurrent patients after initial COVID-19 (2.4 ± 0.610; p < 0.0 0 01) and after recurrence (6.4 ± 11.34; p = 0.007). Virus genome sequencing identified reinfection by a different isolate in one patient. Conclusions: This is the first detailed case series showing COVID-19 recurrence with qRT-PCR positivity. For one individual detection of phylogenetically distinct genomic sequences in the first and second episodes confirmed bona fide renfection, but in most cases the data do not formally distinguish between reinfection and re-emergence of a chronic infection reservoir. These episodes were significantly associated with reduced Ab response during initial disease and argue the need for ongoing vigilance without an assumption of protection after a first episode.

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BackgroundSerologic detection of Zika virus (ZIKV) infections is challenging because of antigenic similarities among flaviviruses.ObjectiveTo evaluate the sensitivity and specificity of commercial ZIKV IgM and IgG enzyme-linked immunoassay (ELISA) kits.MethodsWe used sera from febrile patients with RT-PCR-confirmed ZIKV infection to determine sensitivity and sera from RT-PCR-confirmed dengue cases and blood donors, both of which were collected before ZIKV epidemics in Brazil (2009–2011 and 2013, respectively) to determine specificity.ResultsThe ZIKV IgM-ELISA positivity among RT-PCR ZIKV confirmed cases was 0.0% (0/14) and 12.5% (1/8) for acute- and convalescent-phase sera, respectively, while its specificity was 100.0% (58/58) and 98.3% (58/59) for acute- and convalescent-phase sera of dengue patients, and 100.0% (23/23) for blood donors. The ZIKV IgG-ELISA sensitivity was 100.0% (6/6) on convalescent-phase sera from RT-PCR confirmed ZIKV patients, while its specificity was 27.3% (15/55) on convalescent-phase sera from dengue patients and 45.0% (9/20) on blood donors’ sera. The ZIKV IgG-ELISA specificity among dengue confirmed cases was much greater among patients with primary dengue (92.3%; 12/13), compared to secondary dengue (7.1%; 3/42).ConclusionsIn a setting of endemic dengue transmission, the ZIKV IgM-ELISA had high specificity, but poor sensitivity. In contrast, the ZIKV IgG-ELISA showed low specificity, particularly for patients previously exposed to dengue infections. This suggests that this ZIKV IgM-ELISA is not useful in confirming a diagnosis of ZIKV infection in suspected patients, whereas the IgG-ELISA is more suitable for ZIKV diagnosis among travelers, who reside in areas free of flavivirus transmission, rather than for serosurveys in dengue-endemic areas.

AbsractWe report the presence of Chikungunya (CHIKV) RNA in the blood, urine and semen during the acute phase of the disease in an adult with a dual infection with Dengue virus type 3. The patient, a 25 yr-old man from Salvador, Brazil, reported a 6-day duration of high fever, arthralgia, myalgia, headache and photophobia.Blood and semen specimens were positive for CHIKV in the first collected samples; semen and urine specimens were positive for CHIKV after 30 days of symptoms onset. DENV-3 RNA was positive in blood specimen when first collected 6 days after the initiation of symptoms.We describe for the first time the presence of CHIKV RNA in urine and semen for an extended period of time and we address the possible implications of these findings for diagnosis and transmission dynamics.

Sequencing of isolates from patients in Bahia, Brazil, where most Zika virus cases in Brazil have been reported, resulted in 11 whole and partial Zika virus genomes. Phylogenetic analyses revealed a well-supported Bahia-specific Zika virus lineage, which indicates sustained Zika virus circulation in Salvador, Bahia’s capital city, since mid-2014.

Background Rapid diagnosis tests (RDTs) are easy to carry out, provide fast results, and could potentially guide medical treatment decisions. We investigated the performance of a commercially available RDT, which simultaneously detects the non-structural 1 (NS1) dengue virus (DENV) antigen, and IgM and IgG DENV antibodies, using representative serum samples from individuals in a dengue endemic area in Salvador, Brazil. Methodology/Principal findings We evaluated the accuracy of the SD BIOLINE Dengue Duo RDT (Abbott, Santa Clara, USA; former Alere Inc, Waltham, USA) in a random collection of sera. Samples included acute-phase sera from 246 laboratory-confirmed dengue cases and 108 non-dengue febrile patients enrolled in a surveillance study for dengue detection, 73 healthy controls living in the same surveillance community, and 73 blood donors. RDT accuracy was blindly assessed based on the combined results for the NS1 and the IgM test components. The RDT sensitivity was 46.8% (38.6% for the NS1 component and 13.8% for the IgM component). Sensitivity was greater for samples obtained from patients with secondary DENV infections (49.8%) compared to primary infections (31.1%) (P: 0.02) and was also influenced by the result in the confirmatory dengue diagnostic test, ranging from 39.7% for samples of cases confirmed by IgM-ELISA seroconversion between paired samples to 90.4% for samples of cases confirmed by a positive NS1-ELISA. The RDT specificity was 94.4% for non-dengue febrile patients, 87.7% for the community healthy controls, and 95.9% for the blood donors. Conclusions/Significance The SD BIOLINE Dengue Duo RDT showed good specificities, but low sensitivity, suggesting that it may be more useful to rule in than to rule out a dengue diagnosis in dengue endemic regions.