Daniel Olson

Rapid antigen tests for dengue virus serotypes and Zika virus in patient serum

A low-cost, equipment-free rapid antigen test distinguishes dengue virus serotypes and Zika virus in patient sera without detectable cross-reactivity. Distinguishing dengue from Zika More than mere summer pests, mosquitoes can transmit viruses, such as dengue and Zika. Diagnosing infections of these related flaviviruses can be difficult because of cross-reactivity in diagnostic tests. Bosch et al. developed monoclonal antibodies to detect viral nonstructural 1 (NS1) protein antigens specific to dengue and Zika. Incorporating the antibodies into an immunochromatography format yielded a rapid diagnostic assay that produces a visual readout in the presence of NS1. The assay identified the four dengue serotypes and Zika viral infections without cross-reaction when testing human serum samples from endemic areas in Central and South America and India. This approach could be useful for developing rapid diagnostics for other emerging pathogens. The recent Zika virus (ZIKV) outbreak demonstrates that cost-effective clinical diagnostics are urgently needed to detect and distinguish viral infections to improve patient care. Unlike dengue virus (DENV), ZIKV infections during pregnancy correlate with severe birth defects, including microcephaly and neurological disorders. Because ZIKV and DENV are related flaviviruses, their homologous proteins and nucleic acids can cause cross-reactions and false-positive results in molecular, antigenic, and serologic diagnostics. We report the characterization of monoclonal antibody pairs that have been translated into rapid immunochromatography tests to specifically detect the viral nonstructural 1 (NS1) protein antigen and distinguish the four DENV serotypes (DENV1–4) and ZIKV without cross-reaction. To complement visual test analysis and remove user subjectivity in reading test results, we used image processing and data analysis for data capture and test result quantification. Using a 30-μl serum sample, the sensitivity and specificity values of the DENV1–4 tests and the pan-DENV test, which detects all four dengue serotypes, ranged from 0.76 to 1.00. Sensitivity/specificity for the ZIKV rapid test was 0.81/0.86, respectively, using a 150-μl serum input. Serum ZIKV NS1 protein concentrations were about 10-fold lower than corresponding DENV NS1 concentrations in infected patients; moreover, ZIKV NS1 protein was not detected in polymerase chain reaction–positive patient urine samples. Our rapid immunochromatography approach and reagents have immediate application in differential clinical diagnosis of acute ZIKV and DENV cases, and the platform can be applied toward developing rapid antigen diagnostics for emerging viruses.

Epidemiology and Molecular Characteristics of Mycoplasma pneumoniae During an Outbreak of M. pneumoniae-Associated Stevens-Johnson Syndrome.

Background: An increase in Mycoplasma pneumoniae-associated Stevens-Johnson syndrome (SJS) cases at a Colorado pediatric hospital led to an outbreak investigation. We describe the epidemiologic and molecular characteristics of M. pneumoniae among SJS case-patients and surrounding community members during the outbreak. Methods: M. pneumoniae polymerase chain reaction-positive respiratory specimens from 5 Colorado hospitals and 4 referral laboratories underwent confirmatory polymerase chain reaction testing; positive specimens then underwent multilocus variable-number tandem-repeat analysis (MLVA) and macrolide resistance testing. Three SJS-M. pneumoniae case-patient households were surveyed using a standardized questionnaire, and nasopharyngeal/oropharyngeal swabs were obtained from all consenting/assenting household contacts. International Classification of Diseases, 9th revision codes were used to identify pneumonia cases among Colorado patients 5–21 years of age from January 2009 to March 2014. Results: Three different M. pneumoniae MLVA types were identified among the 5 SJS case-patients with confirmed infection; MLVA type 3-X-6-2 was seen more commonly in SJS case-patients (60%) than in 69 non-SJS community specimens (29%). Macrolide resistance was identified in 7% of community specimens but not among SJS case-patients. Of 15 household contacts, 5 (33%) were M. pneumoniae positive; all MLVA types were identical to those of the corresponding SJS case-patient, although the specimen from 1 contact was macrolide resistant. Overall pneumonia cases as well as those caused by M. pneumoniae specifically peaked in October 2013, coinciding with the SJS outbreak. Conclusions: The outbreak of M. pneumoniae-associated SJS may have been associated with a community outbreak of M. pneumoniae; clinicians should be aware of the M. pneumoniae–SJS relationship. Household transmission of M. pneumoniae was common within the households investigated.

A Rapid Epidemiological Tool to Measure the Burden of Norovirus Infection and Disease in Resource-Limited Settings.

Abstract Background Rapid, cost-effective tools are needed to estimate the disease burden of acute gastroenteritis (AGE) and norovirus (NoV) in resource-limited settings. Methods Households with children (6 weeks–17 years) in rural Guatemala were randomly enrolled into 2 parallel AGE surveillance systems: (1) a prospective cohort, which included an enrollment visit followed by 1 year of prospective observation using a smartphone-based weekly symptom diary; and (2) 2 sequential cross-sectional rapid active sampling (RAS) surveys. Norovirus testing was performed during enrollment (all subjects) and for prospective AGE episodes (prospective cohort only). Results The prospective cohort enrolled 207 households (469 children) from April to September 2015 followed by 471 person-years of observation; RAS survey 1 enrolled 210 households (402 children) during October to November 2015, and RAS survey 2 enrolled 210 separate households (368 children) during January to February 2016. The prospective cohort detected a NoV+ AGE prevalence of 11% and a population-attributable fraction (PAF) of −1.6% at enrollment, followed by an incidence of 1.4 episodes/100 person-years. Rapid active sampling surveys 1 and 2 identified a NoV+ AGE prevalence of 14%–21% and a PAF of 3.2%–12.4%. Conclusions Rapid active sampling surveys were practical and identified more cases of NoV infection and disease compared with a parallel prospective cohort in rural Guatemala.

Pediatric Invasive Pneumococcal Disease in Guatemala City: Importance of Serotype 2.

Introduction: To inform estimations of the potential impact of recently introduced pneumococcal conjugate vaccine (PCV), we report results of 11 years of pre-PCV surveillance for invasive pneumococcal disease (IPD) among children in Guatemala City. Methods: Cases of IPD in children younger than 5 years were identified by active surveillance at 3 referral hospitals in Guatemala City from October 1996 through 2007. Clinical and demographic data were obtained, and isolates of Streptococcus pneumoniae from normally sterile sites were serotyped using latex agglutination and confirmed by Quellung reaction. Results: Four hundred fifty-two cases of IPD were identified with a case fatality rate of 21%. Meningitis was the most common cause of death (77% of all deaths) and occurred more often in infancy (median age 5 months) than other clinical syndromes. Of the 137 isolates serotyped, type 1 (26 cases, 17%), type 2 (25 cases, 16%) and type 5 (18 cases, 12%) were the most common. Serotype 2 was associated with a higher case fatality rate (28%), higher rate of meningitis (68%) and occurred in younger infants (median age, 3.5 months) than other common serotypes. Recently introduced PCV13 includes 73% of observed serotypes in the study. Conclusion: Infants with IPD presented at a young age. Serotype 2, rarely reported as a significant cause of IPD and not included in available PCVs, was a common cause of disease in this population. PCV13 introduction in Guatemala, begun in 2013, may not have as great an impact in disease reduction as has been observed in other countries.

Analysis of the pediatric health information system database as a surveillance tool for travel-associated infectious diseases.

The Pediatric Health Information System (PHIS) database collects admission, diagnostic, and treatment data among 44 childrens hospitals across the United States (U.S.) and presents an opportunity for travel-associated infectious disease (TAID) surveillance. We calculated cumulative incidence rates among children admitted to 16 PHIS hospitals for dengue, malaria, and typhoid, and pooled TAID using discharge codes from 1999 to 2012. We compared incidence rates before, during, and after the 2007-2009 economic recession. Among 16 PHIS hospitals during the study period (1999-2012), incidence of dengue and pooled TAID (malaria, dengue, typhoid fever) increased significantly, and rates of malaria and typhoid trended upward. Admissions for dengue and pooled TAIDs increased significantly among 16 childrens hospitals across the United States from 1999 to 2012. The PHIS database may provide a useful surveillance tool for TAIDs among children in the United States.

Risk factors for death and major morbidity in guatemalan children with acute bacterial meningitis

Background: Acute bacterial meningitis (ABM) remains a significant cause of pediatric illness and death in low and middle income countries. Identifying severity risk factors and predictive scores may guide interventions to reduce poor outcomes. Methods: Data from a prospective surveillance study for ABM in children aged 0–59 months admitted to 3 referral hospitals in Guatemala City from 2000 to 2007 were analyzed. ABM was defined as positive cerebrospinal fluid (CSF) culture, positive latex agglutination or CSF white blood cell greater than 100 cells/mL. Univariate and multivariate analyses of risk factors at hospital admission that predicted major morbidity or death during hospitalization were performed, along with validation of the predictive Herson–Todd score (HTS). Results: Of 809 children with ABM episodes, 221 (27.3%) survived with major morbidity and 192 (23.7%) died. Among 383 children with nonmissing data, the most significant multivariate predictors for death or major morbidity were seizure [odds ratio (OR), 101.5; P < 0.001], CSF glucose less than 20 mg/dL (OR, 5.3; P = 0.0004), symptom duration more than 3 days (OR, 3.7; P = 0.003) and coma (OR, 6.3; P = 0.004). Of 221 children with a HTS greater than 5, 204 (92%) died or suffered major morbidity (OR, 10.3; P < 0.0001). Conclusion: ABM is a cause of considerable morbidity and mortality in Guatemala. Several clinical risk factors and the composite HTS predicted death or major morbidity. These predictors could help clinicians in low and middle income country guide medical care for ABM and could contribute to the public health impact assessment in preventing meningitis with vaccines.

Knowledge of Norovirus and Attitudes toward a Potential Norovirus Vaccine in Rural Guatemala: A Cross-Sectional Exploratory Survey

Given limited data on norovirus vaccine acceptance, we performed an exploratory survey in a rural Guatemalan community on knowledge, interest, and willingness to pay (WTP) for a norovirus vaccine. Cluster-randomized households with children aged 6 weeks to 17 years were enrolled into one of two norovirus surveillance studies: 1) a prospective cohort (N = 207 households) and 2) two separate, community-based, cross-sectional surveys (N = 420 households). After completion of the surveillance study, vaccine surveys were completed by 564 (90%) of 627 households. Most households correctly answered questions regarding norovirus symptoms and transmission; 97% indicated interest in a hypothetical norovirus vaccine. Households with higher education had greater WTP for a vaccine (prevalence ratios = 2.2, 95% confidence interval: 1.2-3.1) and households with lower WTP were more likely to use pharmacies, the Ministry of Health, and radios for health care and information. These results suggest that a future norovirus vaccination program could be acceptable and feasible even in rural areas.

Baseline microcephaly prevalence in rural Guatemala: implications for neonatal screening for congenital Zika virus infection

Abstract Background Microcephaly is the result of disturbance in early brain development and has various causes. Zika was identified in Central America in early 2015. Establishing baseline microcephaly rates in areas affected by Zika is important for the assessment of the burden and contribution of Zika to microcephaly in low-resource settings. Methods We undertook a retrospective review of records from a community wellness programme in rural Guatemala where trained community health workers obtained data on weight, length, and head circumference for infants aged 0 to 13 days, enrolled in the programme between August 1, 2014, and March 31, 2016. We estimated gestational age using a Z-score of zero for length on the modified Fenton growth curve. Z-scores for head circumference and weight, adjusted for gestational age and sex, were then calculated. We used univariate logistic regression to test associations between microcephaly and low weight (Z ≤−1), small size for gestational age (weight below 10th percentile for gestational age), and sex. We analysed head circumference Z-scores and microcephaly for changes over time using birth month as well as multiple time-breaks (we compared infants born before versus after April 30, 2015; October 31, 2015; and January 31, 2016) with Student t-tests, and logistic and linear regression. Findings We included 296 infants: mean head circumference Z-score was −0·68 (95% CI −0·78 to −0·58). 20 infants (6·8%) had a head circumference Z-score ≤–2 and were considered to have microcephaly, giving a microcephaly prevalence of 676 per 10 000 livebirths. One infant (0·3%) had a head circumference Z-score ≤–3. Weight ≤–1 SD (OR 4·59 (1·69–12·41, p=0·003) and small for gestational age (6·65, 1·88–23·55, p=0·003) were associated with microcephaly. Sex was not significantly associated with microcephaly. Birth month and time-breaks were not associated with microcephaly nor with head circumference Z score. Interpretation Baseline neonatal microcephaly present in this rural Guatemalan community before and during Guatemalas early Zika epidemic is more than 100 and 300 times higher than baseline rates reported before the Zika virus epidemic in Puerto Rico and Brazil, respectively. Increased microcephaly rate associated with Zika epidemics in other countries was not detectable in our study population, probably because data were collected early in the Zika epidemic. High baseline microcephaly rates have important implications for neonatal screening programmes to identify infants congenitally infected with Zika in low-income countries. Funding The Center for Global Health at the University of Colorado and the Jose Fernando Bolanos Menendez Foundation provided funding for the wellness programme.

Rapid Active Sampling Surveys as a Tool to Evaluate Factors Associated with Acute Gastroenteritis and Norovirus Infection among Children in Rural Guatemala

We examined burden and factors associated with norovirus (NoV) acute gastroenteritis (AGE) among children in rural Guatemala. Children age 6 weeks to 17 years were enrolled into three AGE surveillance groups, using two-stage cluster sampling: a prospective participatory syndromic surveillance (PSS) cohort and two cross-sectional rapid active sampling (RAS) surveys, conducted from April 2015 to February 2016. Epidemiologic and NoV testing data were used to identify factors associated with NoV infection, AGE, and NoV+ AGE. The three cross-sectional surveys (PSS enrollment visit, RAS Survey 1, and RAS Survey 2) enrolled 1,239 children, who reported 134 (11%) AGE cases, with 20% of AGE and 11% of non-AGE samples positive for NoV. Adjusted analyses identified several modifiable factors associated with AGE and NoV infection. The cross-sectional RAS surveys were practical and cost-effective in identifying population-level risk factors for AGE and NoV, supporting their use as a tool to direct limited public health resources toward high-risk populations.

Visual Diagnosis: 19-year-old Boy with Syncope and Bradycardia.

1. Christina A. Nelson, MD, MPH* 2. Mark A. Farina, PA-C† 3. Daniel Olson, MD‡ 4. Samuel R. Dominguez, MD, PhD‡ 5. Elizabeth J. McFarland, MD‡ 1. *Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO. 2. †Division of Pediatric Cardiology, Childrens Hospital Colorado, Aurora, CO. 3. ‡Department of Pediatric Infectious Diseases, Childrens Hospital Colorado and University of Colorado School of Medicine, Aurora, CO. A 19-year-old adolescent with Asperger syndrome experiences a syncopal episode during which he falls and strikes his head while standing outdoors with friends. The episode occurs in June in Colorado, where the patient and his family live. Emergency medical personnel find the patient conscious but experiencing bradycardia upon their arrival. The patient does not remember the episode, does not report any presyncopal symptoms, and states that he had been feeling well earlier that day. He has no prior history of syncopal episodes or cardiac conditions. Two weeks earlier the patient was seen by his primary care physician for an annual physical examination and noted to have bradycardia, with a heart rate of approximately 40 beats per minute. He was otherwise well and reported no recent constitutional symptoms, respiratory illness, rash, or cardiac-related symptoms such as palpitations. Sinus bradycardia was confirmed by electrocardiography (ECG) with no other abnormalities, and the patient was referred for outpatient cardiology evaluation. A pre-visit 24-hour ambulatory ECG demonstrated predominantly sinus rhythm with second-degree (Wenckebach also known as Mobitz type 1 block.) atrioventricular (AV) block (Fig 1A) and periods of complete AV block (Fig 1B). However, this result and findings from the cardiology evaluation were pending at the time of the syncopal episode. Figure 1. Electrocardiogram tracing from 24-hour ambulatory monitoring 6 days before the patient’s hospital admission revealed: A) predominantly sinus rhythm with second-degree …