Dietary Patterns and Anti-Flavivirus IgG Seroconversion in Colombian Children

The burden of flaviviral infections, especially dengue and Zika, is high in the Americas. Malnutrition affects the risk and response to infections, but the role of diet on flaviviral infection risk is uncertain. The objective of this study was to investigate the relations between dietary patterns adherence and anti-flavivirus IgG seroconversion in children during a Zika epidemic in a dengue-endemic area of Colombia. In 2015-2016, we followed 424 anti-flavivirus IgG seronegative children aged 2 to 12 years for 1 year. Baseline data included children's sociodemographic, anthropometric, and dietary information collected through a 38-item food frequency questionnaire (FFQ). IgG testing was repeated at the end of follow-up. The primary exposure was adherence to each of four dietary patterns (animal foods, traditional, ultraprocessed foods, and prudent) that were identified from the FFQ through principal component analysis. Secondary exposures were intake frequencies of foods contributing to relevant patterns. We estimated risk of seroconversion by quartiles of adherence scores and compared them using relative risks (RR) and 95% CI from Poisson regression adjusted for sex, age, and socioeconomic status indicators. Seroconversion risk was 32.1%. Adherence to the traditional pattern was positively related to seroconversion. RR comparing fourth versus first quartiles of adherence was 1.52 (95% CI: 1.04-2.21; P trend = 0.02). Of the most representative foods in this pattern, potato and sugarcane water intake frequencies were related to increased seroconversion risk. In conclusion, adherence to a traditional foods pattern, including potatoes and sugarcane water, was positively associated with anti-flavivirus IgG seroconversion.

Serotype-specific detection of dengue viruses in a nonstructural protein 1-based enzyme-linked immunosorbent assay validated with a multi-national cohort

BACKGROUND

Dengue virus (DENV) infections pose one of the largest global barriers to human health. The four serotypes (DENV 1-4) present different symptoms and influence immune response to subsequent DENV infections, rendering surveillance, risk assessments, and disease control particularly challenging. Early diagnosis and appropriate clinical management is critical and can be achieved by detecting DENV nonstructural protein 1 (NS1) in serum during the acute phase. However, few NS1-based tests have been developed that are capable of differentiating DENV serotypes and none are currently commercially available.

METHODOLOGY/PRINCIPLE FINDINGS

We developed an enzyme-linked immunosorbent assay (ELISA) to distinguish DENV-1-4 NS1 using serotype-specific pairs of monoclonal antibodies. A total of 1,046 antibodies were harvested from DENV-immunized mice and screened for antigen binding affinity. ELISA clinical performance was evaluated using 408 polymerase chain reaction-confirmed dengue samples obtained from patients in Brazil, Honduras, and India. The overall sensitivity of the test for pan-DENV was 79.66% (325/408), and the sensitivities for DENV-1-4 serotyping were 79.1% (38/48), 80.41% (78/97), 100% (45/45), and 79.6% (98/123), respectively. Specificity reached 94.07-100%.

SIGNIFICANCE

Our study demonstrates a robust antibody screening strategy that enabled the development of a serotype NS1-based ELISA with maximized specific and sensitive antigen binding. This sensitive and specific assay also utilized the most expansive cohort to date, and of which about half are from Latin America, a geographic region severely underrepresented in previous similar studies. This ELISA test offers potential enhanced diagnostics during the acute phase of infection to help guide patient care and disease control. These results indicate that this ELISA is a promising aid in early DENV-1-4 diagnosis and surveillance in regions of endemicity in addition to offer convenient monitoring for future vaccine interventions.

Study protocol for the multicentre cohorts of Zika virus infection in pregnant women, infants, and acute clinical cases in Latin America and the Caribbean: the ZIKAlliance consortium

Background

The European Commission (EC) Horizon 2020 (H2020)-funded ZIKAlliance Consortium designed a multicentre study including pregnant women (PW), children (CH) and natural history (NH) cohorts. Clinical sites were selected over a wide geographic range within Latin America and the Caribbean, taking into account the dynamic course of the ZIKV epidemic.

Methods

Recruitment to the PW cohort will take place in antenatal care clinics. PW will be enrolled regardless of symptoms and followed over the course of pregnancy, approximately every 4 weeks. PW will be revisited at delivery (or after miscarriage/abortion) to assess birth outcomes, including microcephaly and other congenital abnormalities according to the evolving definition of congenital Zika syndrome (CZS).

After birth, children will be followed for 2 years in the CH cohort. Follow-up visits are scheduled at ages 1–3, 4–6, 12, and 24 months to assess neurocognitive and developmental milestones. In addition, a NH cohort for the characterization of symptomatic rash/fever illness was designed, including follow-up to capture persisting health problems.

Blood, urine, and other biological materials will be collected, and tested for ZIKV and other relevant arboviral diseases (dengue, chikungunya, yellow fever) using RT-PCR or serological methods. A virtual, decentralized biobank will be created. Reciprocal clinical monitoring has been established between partner sites.

Substudies of ZIKV seroprevalence, transmission clustering, disabilities and health economics, viral kinetics, the potential role of antibody enhancement, and co-infections will be linked to the cohort studies.

Discussion

Results of these large cohort studies will provide better risk estimates for birth defects and other developmental abnormalities associated with ZIKV infection including possible co-factors for the variability of risk estimates between other countries and regions. Additional outcomes include incidence and transmission estimates of ZIKV during and after pregnancy, characterization of short and long-term clinical course following infection and viral kinetics of ZIKV.

Study registrations

clinicaltrials.gov NCT03188731 (PW cohort), June 15, 2017; clinicaltrials.gov NCT03393286 (CH cohort), January 8, 2018; clinicaltrials.gov NCT03204409 (NH cohort), July 2, 2017.

Clinical Indicators of Fatal Dengue in Two Endemic Areas of Colombia: A Hospital-Based Case-Control Study

According to the World Health Organization, 98% of fatal dengue cases can be prevented; however, endemic countries such as Colombia have recorded higher case fatality rates during recent epidemics. We aimed to identify the predictors of mortality that allow risk stratification and timely intervention in patients with dengue. We conducted a hospital-based, case-control (1:2) study in two endemic areas of Colombia (2009-2015). Fatal cases were defined as having either 1) positive serological test (IgM or NS1), 2) positive virological test (RT-PCR or viral isolation), or 3) autopsy findings compatible with death from dengue. Controls (matched by state and year) were hospitalized nonfatal patients and had a positive serological or virological dengue test. Exposure data were extracted from medical records by trained staff. We used conditional logistic regression (adjusting for age, gender, disease's duration, and health-care provider) in the context of multiple imputation to estimate exposure to case-control associations. We evaluated 110 cases and 217 controls (mean age: 35.0 versus 18.9; disease's duration pre-admission: 4.9 versus 5.0 days). In multivariable analysis, retro-ocular pain (odds ratios [OR] = 0.23), nausea (OR = 0.29), and diarrhea (OR = 0.19) were less prevalent among fatal than nonfatal cases, whereas increased age (OR = 2.46 per 10 years), respiratory distress (OR = 16.3), impaired consciousness (OR = 15.9), jaundice (OR = 32.2), and increased heart rate (OR = 2.01 per 10 beats per minute) increased the likelihood of death (AUC: 0.97, 95% confidence interval: 0.96, 0.99). These results provide evidence that features of severe dengue are associated with higher mortality, which strengthens the recommendations related to triaging patients in dengue-endemic areas.

[Dengue-related hepatic compromise in children from the Huila department of Colombia]

OBJECTIVE

Dengue is the most important arthropod-borne viral disease in the world; it can be life-threatening because of liver involvement. Aim Determining liver involvement frequency and severity in dengue-infected children.

METHODS

This was a descriptive case series study which involved studying 108 dengue-infected children aged less than 13 years old whose infection had been confirmed by the detection of dengue-specific IgM and NS1 in plasma. Clinical and biochemical parameters were used for evaluating liver involvement, including transaminases and albumin. Hepatitis A and leptospira infection were also evaluated by using ELISA to detect pathogen-specific IgM in plasma during acute and convalescence phases. The study was carried out at a teaching hospital in Neiva from June 2009 to May 2010.

RESULTS

Ninety-eight of the aforementioned cases were clinically classified as dengue with warning signs (DWS) and 10 as severe dengue (SD). Two out of three DWS patients and all SD patients had some degree of liver involvement, shown clinically and biochemically. Regardless of the clinical classification, hepatomegaly was the main clinical sign of liver involvement and was present in 85% of all the children in the study. It is worth noting that 5 patients had probable dengue and leptospirosis co-infection, this being the first instance of this in Colombia. None of the cases analyzed here had acute hepatitis A.

CONCLUSIONS

Liver compromise should be considered in confirmed cases of dengue as shown in this series of children. Leptospirosis must be considered as differential diagnosis and also as causing co-infection in a febrile child.

Comparison of the diagnostic accuracy of commercial NS1-based diagnostic tests for early dengue infection

Background

We compared the diagnostic accuracy and reproducibility of commercially available NS1-based dengue tests and explored factors influencing their sensitivities.

Methods

Paired analysis of 310 samples previously characterized as positive (n = 218) and negative (n = 92) for viral isolation and/or RT-PCR and/or IgM seroconversion. Masked samples were tested by two observers with Platelia™ Dengue NS1 Ag, second generation Pan-E™ Dengue Early ELISA, SD Dengue NS1 Ag ELISA, Dengue NS1 Ag STRIP™, and SD BIOLINE™ Dengue Duo (NS1/IgM/IgG).

Results

SD BIOLINE™ NS1/IgM/IgG had the highest sensitivity (80.7% 95%CI 75-85.7) with likelihood ratios of 7.4 (95%CI 4.1-13.8) and 0.21 (95%CI 0.16-0.28). The ELISA-format tests showed comparable sensitivities; all below 75%. STRIP™ and SD NS1 had even lower sensitivities (<65%). The sensitivities significantly decreased in samples taken after 3 days of fever onset, in secondary infections, viral serotypes 2 and 4, and severe dengue. Adding IgM or IgG to SD NS1 increased its sensitivity in all these situations.

Conclusions

The simultaneous detection of NS1/IgM/IgG would be potentially useful for dengue diagnosis in both endemic and non endemic areas. A negative result does not rule out dengue. Further studies are required to assess the performance and impact of early laboratory diagnosis of dengue in the routine clinical setting.

Morphological study of a variant of Paracoccidioides brasiliensis that exists in the yeast form at room temperature

Incubation of Paracoccidioides brasiliensis conidia at 20-25 degrees C (RT) results in two types of colonies, mycelial (M) and yeast (YRT). A study of the latter colonies was undertaken. Conidia were plated in complex (BHI) and chemically-defined media (CDCM), with and without fetal calf serum (FCS). Incubation was carried out at 21 degrees C for 4 weeks. The mean number of YRT colonies was approximately 18.5% on BHI agar. Selected YRT colonies were transferred to liquid CDCM, incubated 7 days at 21 degrees C and transferred to solid media; YRT appearance was preserved in 95% of the colonies if media were FCS-supplemented; otherwise, most colonies reverted to the M form. When FCS was replaced by bovine albumin or by alpha-globulin, 63% and 68% respectively of the colonies obtained after plating YRT cells, became mycelial. Comparative morphologic studies of both YRT and yeasts grown at 37 degrees C suggested that there were no major differences between these two types of yeast cells when size and budding were taken into consideration. The results indicate that in this particular variant, dimorphism is not exclusively temperature-dependent.

Cytomegalovirus infection with acute erosive esophagitis

A healthy young adult is described in whom acute erosive esophagitis developed four weeks after undergoing splenectomy and receiving six units of blood because of trauma. Cytomegalovirus inclusion bodies were identified in esophageal mucosa, and cytomegalovirus was cultured from blood and throat. Within three weeks, the patient's anticytomegalovirus antibody had increased four-fold. The patient was initially anergic and had a titer of antinuclear antibody of 1:10,240. His symptoms and histopathologic findings disappeared over five weeks, and his immunologic abnormalities were partially corrected. It is suggested that cytomegalovirus was the primary cause of gastrointestinal disease in this nonimmunocompromised patient.

Brain abscess due to penicillin- and clindamycin-resistant Bacteroides melaninogenicus

The case of a patient with severe anaerobic infection, a brain abscess, is presented. The causative organism was a penicillinase-producing, clindamycin-resistant strain of Bacteroides melaninogenicus. Treatment with adequate doses of penicillin G failed. Findings in this case suggest caution when basing therapy on the untested assumption that B. melaninogenicus is routinely susceptible to penicillin and clindamycin therapy.