Obesity is associated with increased pediatric dengue virus infection and disease: A 9-year cohort study in Managua, Nicaragua

Background

Obesity is on the rise globally in adults and children, including in tropical areas where diseases such as dengue have a substantial burden, particularly in children. Obesity impacts the risk of severe dengue disease; however, the impact on dengue virus (DENV) infection and dengue cases remains an open question.

Methods

We used 9 years of data from 5,940 children in the Pediatric Dengue Cohort Study in Nicaragua to examine whether pediatric obesity is associated with increased susceptibility to DENV infection and symptomatic presentation. Analysis was performed using Generalized Estimating Equations adjusted for age, sex, and pre-infection DENV antibody titers.

Results

From 2011 to 2019, children contributed 26,273 person-years of observation, and we observed an increase in the prevalence of overweight (from 12% to 17%) and obesity (from 7% to 13%). There were 1,682 DENV infections and 476 dengue cases in the study population. Compared to participants with normal weight, participants with obesity had higher odds of DENV infection (Adjusted Odds Ratio [aOR] 1.21, 95% confidence interval [CI] 1.03-1.42) and higher odds of dengue disease given infection (aOR 1.59, 95% CI 1.15-2.19). Children with obesity infected with DENV showed increased odds of presenting fever (aOR 1.46, 95% CI 1.05-2.02), headache (aOR 1.51, 95% CI 1.07-2.14), and rash (aOR 2.26, 95% CI 1.49-3.44) when compared with children with normal weight.

Conclusions

Our results indicate that obesity is associated with increased susceptibility to DENV infection and dengue cases in children, independently of age, sex, and pre-infection DENV antibody titers.

Dengue severity by serotype in 19 years of pediatric clinical studies in Nicaragua

Background

Dengue virus, a major global health threat, consists of four serotypes (DENV1-4) that cause a range of clinical manifestations from mild to severe and potentially fatal disease.

Methods

This study, based on 19 years of data from the Pediatric Dengue Cohort Study and Pediatric Dengue Hospital-based Study in Managua, Nicaragua, investigates the influence of serotype and immune status on dengue severity. Study participants 6 months to 17 years old were followed during their hospital stay or as ambulatory patients, with dengue cases confirmed by molecular, serological, and/or virological methods.

Results

We enrolled a total of 14071 participants, of whom 2954 (21%) were positive for DENV infection. Of 2425 cases with serotype result by RT-PCR, 541 corresponded to DENV1, 996 to DENV2, 718 to DENV3 and 170 to DENV4. Severe disease was more prevalent among secondary DENV2 and DENV4 cases, while similar disease severity was observed in both primary and secondary DENV1 and DENV3 cases. According to the 1997 World Health Organization (WHO) severity classification, both DENV2 and DENV3 had a higher proportion of severe disease compared to other serotypes, whereas DENV3 had the greatest percentage of severity under the WHO-2009 classification. DENV2 was associated with pleural effusion and low platelet count, while DENV3 correlated with both hypotensive and compensated shock.

Conclusions

These findings emphasize the critical need for a dengue vaccine with balanced efficacy against all four serotypes, particularly as existing vaccines show variable efficacy by serotype and immune status, posing challenges for comprehensive protection, particularly in dengue-naïve individuals.

Advanced wound healing in a patient with transmetatarsal amputation caused by severe diabetic foot infection: A case report

Introduction and importance: Diabetic foot accounts for 50% to 95 % of non-traumatic amputations. The healing process of a surgical wound resulting from amputation in the diabetic foot is complex, and it is difficult to achieve an optimal outcome, which should include obtaining a functional stump for the patient. Healing is mainly hindered by infection, vascular disease, and wound size. In turn, biofilm formation significantly delays the healing process, increasing morbidity and impairing the amputee's quality of life. Case presentation: This study analyzes the case of an 80-year-old male patient with diabetes who had failed to respond to previous treatment on an infected wound from a transmetatarsal amputation. The new treatment involved spraying the wound with silver sulfadiazine, lidocaine, and vitamin A aerosol and covering it with gauze dressings soaked in silver sulfadiazine, lidocaine, and vitamin A. The case evolution indicators used were total wound area, percentage of granulation tissue, wound perimeter, and maximum distance between the wound edges. A 3D simulation was also used to assess the wound bed. Clinical Discussion: Biofilm is linked to slower wound healing and wound chronicity, as this community of microorganisms in the wound slows down healing even when there are no apparent signs of infection. Therefore, treatment should be geared toward preventing contamination from leading to biofilm formation. Conclusion: Our results show that silver sulfadiazine, lidocaine, vitamin A gauze dressings, and aerosol have promoted fast and effective healing in a diabetic patient with a wound at high risk of greater amputation.

Longitudinal analysis of post-acute chikungunya-associated arthralgia in children and adults: A prospective cohort study in Managua, Nicaragua (2014-2018)

Chikungunya can result in debilitating arthralgia, often presenting as acute, self-limited pain, but occasionally manifesting chronically. Little is known about differences in chikungunya-associated arthralgia comparing children to adults over time. To characterize long-term chikungunya-associated arthralgia, we recruited 770 patients (105 0-4 years old [y/o], 200 5-9 y/o, 307 10-15 y/o, and 158 16+ y/o) with symptomatic chikungunya virus infections in Managua, Nicaragua, during two consecutive chikungunya epidemics (2014-2015). Participants were assessed at ~15 days and 1, 3, 6, 12, and 18 months post-fever onset. Following clinical guidelines, we defined participants by their last reported instance of arthralgia as acute (≤10 days post-fever onset), interim (>10 and <90 days), or chronic (≥90 days) cases. We observed a high prevalence of arthralgia (80-95%) across all ages over the study period. Overall, the odds of acute arthralgia increased in an age-dependent manner, with the lowest odds of arthralgia in the 0-4 y/o group (odds ratio [OR]: 0.27, 95% confidence interval [CI]: 0.14-0.51) and the highest odds of arthralgia in the 16+ y/o participants (OR: 4.91, 95% CI: 1.42-30.95) relative to 10-15 y/o participants. Females had higher odds of acute arthralgia than males (OR: 1.63, 95% CI: 1.01-2.65) across all ages. We found that 23-36% of pediatric and 53% of adult participants reported an instance of post-acute arthralgia. Children exhibited the highest prevalence of post-acute polyarthralgia in their legs, followed by the hands and torso - a pattern not seen among adult participants. Further, we observed pediatric chikungunya presenting in two distinct phases: the acute phase and the subsequent interim/chronic phases. Thus, differences in the presentation of arthralgia were observed across age, sex, and disease phase in this longitudinal chikungunya cohort. Our results elucidate the long-term burden of chikungunya-associated arthralgia among pediatric and adult populations.

Effects of boosting and waning in highly exposed populations on dengue epidemic dynamics

Sequential infection with multiple dengue virus (DENV) serotypes is thought to induce enduring protection against dengue disease. However, long-term antibody waning has been observed after repeated DENV infection. Here, we provide evidence that highly immune Nicaraguan children and adults (n = 4478) experience boosting and waning of antibodies during and after major Zika and dengue epidemics. We develop a susceptible-infected-recovered-susceptible (SIRS-type) model that tracks immunity by titer rather than number of infections to show that boosts in highly immune individuals can contribute to herd immunity, delaying their susceptibility to transmissible infection. In contrast, our model of lifelong immunity in highly immune individuals, as previously assumed, results in complete disease eradication after introduction. Periodic epidemics under this scenario can only be sustained with a constant influx of infected individuals into the population or a high basic reproductive number. We also find that Zika virus infection can boost DENV immunity and produce delays and then surges in dengue epidemics, as observed with real epidemiological data. This work provides insight into factors shaping periodicity in dengue incidence and may inform vaccine efforts to maintain population immunity.

Infection-Induced Immunity Is Associated With Protection Against Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Decreased Infectivity

BACKGROUND

The impact of infection-induced immunity on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission has not been well established. Here we estimate the effects of prior infection induced immunity in adults and children on SARS-CoV-2 transmission in households.

METHODS

We conducted a household cohort study from March 2020-November 2022 in Managua, Nicaragua; following a housheold SARS-CoV-2 infection, household members are closely monitored for infection. We estimate the association of time period, age, symptoms, and prior infection with secondary attack risk.

RESULTS

Overall, transmission occurred in 70.2% of households, 40.9% of household contacts were infected, and the secondary attack risk ranged from 8.1% to 13.9% depending on the time period. Symptomatic infected individuals were more infectious (rate ratio [RR] 21.2, 95% confidence interval [CI]: 7.4-60.7) and participants with a prior infection were half as likely to be infected compared to naïve individuals (RR 0.52, 95% CI:.38-.70). In models stratified by age, prior infection was associated with decreased infectivity in adults and adolescents (secondary attack risk [SAR] 12.3, 95% CI: 10.3, 14.8 vs 17.5, 95% CI: 14.8, 20.7). However, although young children were less likely to transmit, neither prior infection nor symptom presentation was associated with infectivity. During the Omicron era, infection-induced immunity remained protective against infection.

CONCLUSIONS

Infection-induced immunity is associated with decreased infectivity for adults and adolescents. Although young children are less infectious, prior infection and asymptomatic presentation did not reduce their infectivity as was seen in adults. As SARS-CoV-2 transitions to endemicity, children may become more important in transmission dynamics.

Longitudinal Analysis of the Burden of Post-Acute Chikungunya-Associated Arthralgia in Children and Adults: A Prospective Cohort Study in Managua, Nicaragua (2014-2019)

Chikungunya can result in debilitating arthralgia, often presenting as acute, self-limited pain, but occasionally manifesting chronically. Little is known about differences in chikungunya-associated arthralgia comparing children to adults over time. To characterize long-term chikungunya-associated arthralgia, we recruited 770 patients (105 0-4 year olds [y/o], 200 5-9 y/o, 307 10-15 y/o, and 158 16+ y/o) with symptomatic chikungunya virus infections in Managua, Nicaragua, during two chikungunya epidemics (2014-2015). Participants were assessed at ~15 days and 1, 3, 6, 12, and 18 months post-fever onset. Following clinical guidelines, we defined participants by their last reported instance of arthralgia as acute (≤10 days post-fever onset), interim (>10 and <90 days), or chronic (≥90 days) cases. We observed a high prevalence of arthralgia (80-95%) across all ages over the study period. Overall, the odds of acute arthralgia increased in an age-dependent manner, with the lowest odds of arthralgia in the 0-4 y/o group (odds ratio [OR]: 0.27, 95% confidence interval [CI]: 0.14-0.51) and the highest odds of arthralgia in the 16+ y/o participants (OR: 4.91, 95% CI: 1.42-30.95) relative to 10-15 y/o participants. Females had a higher odds of acute arthralgia than males (OR: 1.63, 95% CI: 1.01-2.65) across all ages. We found that 23-36% of pediatric and 53% of adult participants reported an instance of post-acute arthralgia. Children exhibited the highest prevalence of post-acute polyarthralgia in their legs, followed by the hands and torso - a pattern not seen among adult participants. Further, we observed pediatric chikungunya presenting in two distinct phases: the acute phase and the associated interim and chronic phases. Differences in the presentation of arthralgia were observed across age, sex, and disease phase in this longitudinal chikungunya cohort. Our results elucidate the long-term burden of chikungunya-associated arthralgia among pediatric and adult populations.

Technical Aspects of Using a Second Magnetic Grasper to Improve the Surgical Field in Single Port Revisional Bariatric Surgery

BACKGROUND

The future of minimally invasive surgery in revisional surgery is experiencing changes with new equipment such as the magnetic assistance that can be used with single port devices in order to perform an incisionless surgery (Luengas R, Galindo J, Castro M, et al. Surg Obes Relat Dis. 2021;17(1):147-152). Magnetic assistance through an auxiliary grasper with two internal magnets serves beyond liver retraction in different steps of the surgery improving the surgical field by obtaining a better visualization and triangulation.

PURPOSE

Expose the feasibility of using two internal magnetic graspers by single port performing a conversion surgery of sleeve gastrectomy (SG) to Roux-en-Y gastric bypass (RYGB).

METHODS

A 36-year-old female patient underwent a SG in 2015 and consults in 2021 because of severe GERD with a 33-point GERD-HRQL score. She has preoperative evaluation for a conversion surgery from SG to RYGB. Using a single port device through the umbilicus, an additional 5 mm trocar was placed in the left side of the abdomen. Two internal magnets were introduced through the umbilicus, and they were controlled by two external magnets placed over the abdomen with an articulated arm. The first magnet was used for liver retraction and the second one to perform both anastomoses, close the intermesenteric and Petersen defect, acting as an auxiliary grasper. The ethical committee approval was obtained through an informed consent from the participant included in the study.

The Nicaraguan Pediatric Influenza Cohort Study, 2011-2019: Influenza Incidence, Seasonality, and Transmission

BACKGROUND

Children account for a large portion of global influenza burden and transmission, and a better understanding of influenza in children is needed to improve prevention and control strategies.

METHODS

To examine the incidence and transmission of influenza we conducted a prospective community-based study of children aged 0-14 years in Managua, Nicaragua, between 2011 and 2019. Participants were provided with medical care through study physicians and symptomatic influenza was confirmed by reverse-transcription polymerase chain reaction (RT-PCR). Wavelet analyses were used to examine seasonality. Generalized growth models (GGMs) were used to estimate effective reproduction numbers.

RESULTS

From 2011 to 2019, 3016 children participated, with an average of ∼1800 participants per year and median follow-up time of 5 years per child, and 48.3% of the cohort in 2019 had been enrolled their entire lives. The overall incidence rates per 100 person-years were 14.5 symptomatic influenza cases (95% confidence interval [CI]: 13.9-15.1) and 1.0 influenza-associated acute lower respiratory infection (ALRI) case (95% CI: .8-1.1). Symptomatic influenza incidence peaked at age 9-11 months. Infants born during peak influenza circulation had lower incidence in the first year of their lives. The mean effective reproduction number was 1.2 (range 1.02-1.49), and we observed significant annual patterns for influenza and influenza A, and a 2.5-year period for influenza B.

CONCLUSIONS

This study provides important information for understanding influenza epidemiology and informing influenza vaccine policy. These results will aid in informing strategies to reduce the burden of influenza.

SARS-CoV-2 infection-induced immunity and the duration of viral shedding: Results from a Nicaraguan household cohort study

BACKGROUND

Much of the world's population has been infected with SARS-CoV-2. Thus, immunity from prior infection will play a critical role in future SARS-CoV-2 transmission. We investigated the impact of infection-induced immunity on viral shedding duration and viral load.

METHODS

We conducted a household cohort study in Managua, Nicaragua, with an embedded transmission study that closely monitors participants regardless of symptoms. Real-time reverse-transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assays (ELISAs) were used to measure infections and seropositivity, respectively. Blood samples were collected twice annually and surrounding household intensive monitoring periods. We used accelerated failure time models to compare shedding times. Participants vaccinated ≥14 days prior to infection were excluded from primary analyses.

RESULTS

There were 600 RT-PCR-confirmed SARS-CoV-2 infections in unvaccinated participants between May 1, 2020, and March 10, 2022, with prior ELISA data. Prior infection was associated with 48% shorter shedding times (event time ratio [ETR] 0.52, 95% CI: 0.39-0.69, mean shedding: 13.7 vs. 26.4 days). A fourfold higher anti-SARS-CoV-2 spike titer was associated with 17% shorter shedding (ETR 0.83, 95% CI: 0.78-0.90). Similarly, maximum viral loads (lowest cycle threshold [CT]) were lower for previously infected individuals (mean CT 29.8 vs. 28.0, p = 4.02 × 10^-3 ), for adults and children ≥10 years, but not for children 0-9 years; there was little difference in CT levels for previously infected versus naïve adults aged above 60 years.

CONCLUSIONS

Prior infection-induced immunity was associated with shorter viral shedding and lower viral loads, which may be important in the transition from pandemic to endemicity.

Burden and seasonality of primary and secondary symptomatic common cold coronavirus infections in Nicaraguan children

BACKGROUND

The current SARS-CoV-2 pandemic highlights the need for an increased understanding of coronavirus epidemiology. In a pediatric cohort in Nicaragua, we evaluate the seasonality and burden of common cold coronavirus (ccCoV) infection and evaluate likelihood of symptoms in reinfections.

METHODS

Children presenting with symptoms of respiratory illness were tested for each of the four ccCoVs (NL63, 229E, OC43, and HKU1). Annual blood samples collected before ccCoV infection were tested for antibodies against each ccCoV. Seasonality was evaluated using wavelet and generalized additive model (GAM) analyses, and age-period effects were investigated using a Poisson model. We also evaluate the risk of symptom presentation between primary and secondary infections.

RESULTS

In our cohort of 2576 children from 2011 to 2016, we observed 595 ccCoV infections and 107 cases of ccCoV-associated lower respiratory infection (LRI). The overall incidence rate was 61.1 per 1000 person years (95% confidence interval (CI): 56.3, 66.2). Children under two had the highest incidence of ccCoV infections and associated LRI. ccCoV incidence rapidly decreases until about age 6. Each ccCoV circulated throughout the year and demonstrated annual periodicity. Peaks of NL63 typically occurred 3 months before 229E peaks and 6 months after OC43 peaks. Approximately 69% of symptomatic ccCoV infections were secondary infections. There was slightly lower risk (rate ratio (RR): 0.90, 95% CI: 0.83, 0.97) of LRI between secondary and primary ccCoV infections among participants under the age of 5.

CONCLUSIONS

ccCoV spreads annually among children with the greatest burden among ages 0-1. Reinfection is common; prior infection is associated with slight protection against LRI among the youngest children.

Single-Dose Vaccination Among Infants and Toddlers Provides Modest Protection Against Influenza Illness, Which Wanes After 5 Months

In their first season of vaccination, young children are recommended 2 doses of influenza vaccine, but a 2-dose schedule might be difficult to implement in many countries. Within a cohort study of 742 children aged 6 to <24 months in Managua, Nicaragua, this study estimated effectiveness of partial vaccination from 3 to 9 months postvaccination. Vaccine effectiveness was 74% (95% confidence interval [CI], 24%-91%) within 3 months and 55% (95% CI, 10%-77%) within 4 months. There was not significant protection beyond 5 months. Partial vaccination might confer some benefits but should be followed by a second dose.

High Co-circulation of Influenza and Severe Acute Respiratory Syndrome Coronavirus 2

In the first 2 years of the coronavirus disease 2019 pandemic, influenza transmission decreased substantially worldwide, meaning that health systems were not faced with simultaneous respiratory epidemics. In 2022, however, substantial influenza transmission returned to Nicaragua where it co-circulated with severe acute respiratory syndrome coronavirus 2, causing substantial disease burden.

Respiratory Syncytial Virus Incidence and Severity in a Community-Based Prospective Cohort of Children Aged 0-14 Years

BACKGROUND

Respiratory syncytial virus (RSV) is a substantial source of severe illnesses including acute lower respiratory infections (ALRIs) like pneumonia. However, its burden in older children remains less well understood.

METHODS

Using a community-based prospective cohort, we assessed the burden of symptomatic reverse-transcription polymerase chain reaction-confirmed RSV among Nicaraguan children aged 0-14 years from 2011 to 2016. ALRI was defined as physician diagnosis of pneumonia, bronchiolitis, bronchitis, or bronchial hyperreactivity.

RESULTS

Between 2011 and 2016, 2575 children participated in the cohort. Of these, 630 (24.5%) had at least 1 episode of symptomatic RSV and 194 (7.5%) had multiple episodes. Subtype was identified in 571 (69.3%) episodes with 408 (71.5%) RSV-A, 157 (27.5%) RSV-B, and 6 (1%) positive for both. Children aged <2 years displayed the highest incidence of symptomatic RSV, with 269.3 cases per 1000 person-years (95% confidence interval [CI], 242.1-299.5). Beyond 2 years, incidence (95% CI) of symptomatic RSV decreased rapidly: 145.6 (129.9-163.1), 37.9 (31.9-45.0), and 19.3 (14.9-25.0) cases per 1000 person-years among children aged 2-4, 5-9, and 10-14 years, respectively. Incidence of RSV-associated ALRI was highest in children aged <2 years (85.95 per 1000 person-years [95% CI, 71.30-103.61]): 2.1, 9.5, and 17.3 times that of participants aged 2-4, 5-9, and 10-14 years, respectively. Children <2 years old were significantly more likely to have an RSV-associated hospitalization (P < .001).

CONCLUSIONS

There is a substantial burden of symptomatic and severe RSV in children. While older children did present with RSV, the rates of symptomatic and severe RSV decreased by as much as 95% beyond age 5.

Pediatric burden and seasonality of human metapneumovirus over 5 years in Managua, Nicaragua

BACKGROUND

Human metapneumovirus (hMPV) is an important cause of pediatric respiratory infection. We leveraged the Nicaraguan Pediatric Influenza Cohort Study (NPICS) to assess the burden and seasonality of symptomatic hMPV infection in children.

METHODS

NPICS is an ongoing prospective study of children in Managua, Nicaragua. We assessed children for hMPV infection via real-time reverse-transcription polymerase chain reaction (RT-PCR). We used classical additive decomposition analysis to assess the temporal trends, and generalized growth models (GGMs) were used to estimate effective reproduction numbers.

RESULTS

From 2011 to 2016, there were 564 hMPV symptomatic infections, yielding an incidence rate of 5.74 cases per 100 person-years (95% CI 5.3, 6.2). Children experienced 3509 acute lower respiratory infections (ALRIs), of which 160 (4.6%) were associated with hMPV infection. Children under the age of one had 55% of all symptomatic hMPV infections (62/112) develop into hMPV-associated ALRIs and were five times as likely as children over one to have an hMPV-associated ALRI (rate ratio 5.5 95% CI 4.1, 7.4 p < 0.001). Additionally, symptomatic reinfection with hMPV was common. In total, 87 (15%) of all observed symptomatic infections were detected reinfections. The seasonality of symptomatic hMPV outbreaks varied considerably. From 2011 to 2016, four epidemic periods were observed, following a biennial seasonal pattern. The mean ascending phase of the epidemic periods were 7.7 weeks, with an overall mean estimated reproductive number of 1.2 (95% CI 1.1, 1.4).

CONCLUSIONS

Symptomatic hMPV infection was associated with substantial burden among children in the first year of life. Timing and frequency of symptomatic hMPV incidence followed biennial patterns.

High co-circulation of influenza and SARS-CoV-2.. [PMID: 36299425 PMCID: PMC9603835 DOI: 10.1101/2022.09.13.22279740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

In the first two years of the COVID-19 pandemic, influenza transmission decreased substantially worldwide meaning that health systems were not faced with simultaneous respiratory epidemics. In 2022, however, substantial influenza transmission returned to Nicaragua where it co-circulated with SARS-CoV-2 causing substantial disease burden.

Clinical Spectrum of Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Protection From Symptomatic Reinfection

BACKGROUND

There are few data on the full spectrum of disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection across the lifespan from community-based or nonclinical settings.

METHODS

We followed 2338 people in Managua, Nicaragua, aged <94 years from March 2020 through March 2021. SARS-CoV-2 infection was identified through real-time reverse transcription polymerase chain reaction (RT-PCR) or through enzyme-linked immunosorbent assay. Disease presentation was assessed at the time of infection or retrospectively by survey at the time of blood collection.

RESULTS

There was a large epidemic that peaked between March and August 2020. In total, 129 RT-PCR-positive infections were detected, for an overall incidence rate of 5.3 infections per 100 person-years (95% confidence interval [CI], 4.4-6.3). Seroprevalence was 56.7% (95% CI, 53.5%-60.1%) and was consistent from age 11 through adulthood but was lower in children aged ≤10 years. Overall, 31.0% of the infections were symptomatic, with 54.7% mild, 41.6% moderate, and 3.7% severe. There were 2 deaths that were likely due to SARS-CoV-2 infection, yielding an infection fatality rate of 0.2%. Antibody titers exhibited a J-shaped curve with respect to age, with the lowest titers observed among older children and young adults and the highest among older adults. When compared to SARS-CoV-2-seronegative individuals, SARS-CoV-2 seropositivity at the midyear sample was associated with 93.6% protection from symptomatic reinfection (95% CI, 51.1%-99.2%).

CONCLUSIONS

This population exhibited a very high SARS-CoV-2 seropositivity with lower-than-expected severity, and immunity from natural infection was protective against symptomatic reinfection.

SARS-CoV-2 and endemic coronaviruses: Comparing symptom presentation and severity of symptomatic illness among Nicaraguan children

It has been proposed that as SARS-CoV-2 transitions to endemicity, children will represent the greatest proportion of SARS-Co-V-2 infections as they currently do with endemic coronavirus infections. While SARS-CoV-2 infection severity is low for children, it is unclear if SARS-CoV-2 infections are distinct in symptom presentation, duration, and severity from endemic coronavirus infections in children. We compared symptom risk and duration of endemic human coronavirus (HCoV) infections from 2011–2016 with SARS-CoV-2 infections from March 2020-September 2021 in a Nicaraguan pediatric cohort. Blood samples were collected from study participants annually in February-April. Respiratory samples were collected from participants that met testing criteria. Blood samples collected in were tested for SARS-CoV-2 antibodies and a subset of 2011–2016 blood samples from four-year-old children were tested for endemic HCoV antibodies. Respiratory samples were tested for each of the endemic HCoVs from 2011–2016 and for SARS-CoV-2 from 2020–2021 via rt-PCR. By April 2021, 854 (49%) cohort participants were ELISA positive for SARS-CoV-2 antibodies. Most participants had antibodies against one alpha and one beta coronavirus by age four. We observed 595 symptomatic endemic HCoV infections from 2011–2016 and 121 symptomatic with SARS-CoV-2 infections from March 2020-September 2021. Symptom presentation of SARS-CoV-2 infection and endemic coronavirus infections were very similar, and SARS-CoV-2 symptomatic infections were as or less severe on average than endemic HCoV infections. This suggests that, for children, SARS-CoV-2 may be just another endemic coronavirus. However, questions about the impact of variants and the long-term effects of SARS-CoV-2 remain.

Association of SARS-CoV-2 Seropositivity and Symptomatic Reinfection in Children in Nicaragua

Importance

The impact of the SARS-CoV-2 pandemic on children remains unclear. Better understanding of the burden of COVID-19 among children and their risk of reinfection is crucial, as they will be among the last groups vaccinated.

Objective

To characterize the burden of COVID-19 and assess how risk of symptomatic reinfection may vary by age among children.

Design, Setting, and Participants

In this prospective, community-based pediatric cohort study conducted from March 1, 2020, to October 15, 2021, 1964 nonimmunocompromised children aged 0 to 14 years were enrolled by random selection from the Nicaraguan Pediatric Influenza Cohort, a community-based cohort in District 2 of Managua, Nicaragua. Additional newborn infants aged 4 weeks or younger were randomly selected and enrolled monthly via home visits.

Exposures

Prior COVID-19 infection as confirmed by positive anti-SARS-CoV-2 antibodies (receptor binding domain and spike protein) or real-time reverse transcriptase-polymerase chain reaction (RT-PCR)-confirmed COVID-19 infection at least 60 days before current COVID-19 infection.

Main Outcomes and Measures

Symptomatic COVID-19 cases confirmed by real-time RT-PCR and hospitalization within 28 days of symptom onset of a confirmed COVID-19 case.

Results

This cohort study assessed 1964 children (mean [SD] age, 6.9 [4.4] years; 985 [50.2%] male). Of 1824 children who were tested, 908 (49.8%; 95% CI, 47.5%-52.1%) were seropositive during the study. There were also 207 PCR-confirmed COVID-19 cases, 12 (5.8%) of which were severe enough to require hospitalization. Incidence of COVID-19 was highest among children younger than 2 years (16.1 cases per 100 person-years; 95% CI, 12.5-20.5 cases per 100 person-years), which was approximately 3 times the incidence rate in any other child age group assessed. In addition, 41 symptomatic SARS-CoV-2 episodes (19.8%; 95% CI, 14.4%-25.2%) were reinfections.

Conclusions and Relevance

In this prospective, community-based pediatric cohort study, rates of symptomatic and severe COVID-19 were highest among the youngest participants, with rates stabilizing at approximately 5 years of age. In addition, symptomatic reinfections represented a large proportion of symptomatic COVID-19 cases.

Epidemics of chikungunya, Zika, and COVID-19 reveal bias in case-based mapping

Accurate tracing of epidemic spread over space enables effective control measures. We examined three metrics of infection and disease in a pediatric cohort (N≈3,000) over two chikungunya and one Zika epidemic, and in a household cohort (N=1,793) over one COVID-19 epidemic in Managua, Nicaragua. We compared spatial incidence rates (cases/total population), infection risks (infections/total population), and disease risks (cases/infected population). We used generalized additive and mixed-effects models, Kulldorf's spatial scan statistic, and intracluster correlation coefficients. Across different analyses and all epidemics, incidence rates considerably underestimated infection and disease risks, producing large and spatially non-uniform biases distinct from biases due to incomplete case ascertainment. Infection and disease risks exhibited distinct spatial patterns, and incidence clusters inconsistently identified areas of either risk. While incidence rates are commonly used to infer infection and disease risk in a population, we find that this can induce substantial biases and adversely impact policies to control epidemics.

Homotypic protection against influenza in a pediatric cohort in Managua, Nicaragua

The period of protection from repeat infection following symptomatic influenza is not well established due to limited availability of longitudinal data. Using data from a pediatric cohort in Managua, Nicaragua, we examine the effects of natural influenza virus infection on subsequent infection with the same influenza virus subtype/lineage across multiple seasons, totaling 2,170 RT-PCR-confirmed symptomatic influenza infections. Logistic regression models assessed whether infection in the prior influenza season protected against homologous reinfection. We sequenced viruses from 2011-2019 identifying dominant clades and measuring antigenic distances between hemagglutinin clades. We observe homotypic protection from repeat infection in children infected with influenza A/H1N1pdm (OR 0.12, CI 0.02-0.88), A/H3N2 (OR 0.41, CI 0.24-0.73), and B/Victoria (OR 0.00, CI 0.00-0.14), but not with B/Yamagata viruses (OR 0.60, CI 0.09-2.10). Overall, protection wanes as time or antigenic distance increases. Individuals infected with one subtype or lineage of influenza virus have significantly lower odds of homologous reinfection for the following one to two years; after two years this protection wanes. This protection is demonstrated across multiple seasons, subtypes, and lineages among children.

Burden of SARS-CoV-2 and protection from symptomatic second infection in children

IMPORTANCE

The impact of the SARS-CoV-2 pandemic on children remains unclear. Better understanding of the burden of COVID-19 among children and their protection against re-infection is crucial as they will be among the last groups vaccinated.

OBJECTIVE

To characterize the burden of COVID-19 and assess how protection from symptomatic re-infection among children may vary by age.

DESIGN

A prospective, community-based pediatric cohort study conducted from March 1, 2020 through October 15, 2021.

SETTING

The Nicaraguan Pediatric Influenza Cohort is a community-based cohort in District 2 of Managua, Nicaragua.

PARTICIPANTS

A total of 1964 children aged 0-14 years participated in the cohort. Non-immunocompromised children were enrolled by random selection from a previous pediatric influenza cohort. Additional newborn infants aged ≤4 weeks were randomly selected and enrolled monthly, via home visits.

EXPOSURES

Prior COVID-19 infection as confirmed by positive anti SARS-CoV-2 antibodies (receptor binding domain [RBD] and spike protein) or real time RT-PCR confirmed COVID-19 infection ≥60 days prior to current COVID-19.

MAIN OUTCOMES AND MEASURES

Symptomatic COVID-19 cases confirmed by real time RT-PCR and hospitalization within 28 days of symptom onset of confirmed COVID-19 case.

RESULTS

Overall, 49.8% of children tested were seropositive over the course of the study. There were also 207 PCR-confirmed COVID-19 cases, 12 (6.4%) of which were severe enough to require hospitalization. Incidence of COVID-19 was highest among children aged <2 years-16.1 per 100 person-years (95% Confidence Interval [CI]: 12.5, 20.5)-approximately three times that of children in any other age group assessed. Additionally, 41 (19.8%) symptomatic SARS-CoV-2 episodes were re-infections, with younger children slightly more protected against symptomatic reinfection. Among children aged 6-59 months, protection was 61% (Rate Ratio [RR]:0.39, 95% CI:0.2,0.8), while protection among children aged 5-9 and 10-14 years was 64% (RR:0.36,0.2,0.7), and 49% (RR:0.51,0.3-0.9), respectively.

CONCLUSIONS AND RELEVANCE

In this prospective community-based pediatric cohort rates of symptomatic and severe COVID-19 were highest among the youngest participants, with rates stabilizing around age 5. Reinfections represent a large proportion of PCR-positive cases, with children <10 years displaying greater protection from symptomatic reinfection. A vaccine for children <5 years is urgently needed.

KEY POINTS

Question: What is the burden of COVID-19 among young children and how does protection from re-infection vary with age?Findings: In this study of 1964 children aged 0-14 years children <5 years had the highest rates of symptomatic and severe COVID-19 while also displaying greater protection against re-infection compared to children ≥10 years.Meaning: Given their greater risk of infection and severe disease compared to older children, effective vaccines against COVID-19 are urgently needed for children under 5.

SARS-CoV-2 and endemic coronaviruses: Comparing symptom presentation and severity of symptomatic illness among Nicaraguan children.. [PMID: 35075460 PMCID: PMC8786229 DOI: 10.1101/2021.12.09.21267537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

It has been proposed that as SARS-CoV-2 transitions to endemicity, children will represent the greatest proportion of SARS-Co-V-2 infections as they currently do with endemic coronavirus infections. While SARS-CoV-2 infection severity is low for children, it is unclear if SARS-CoV-2 infections are distinct in symptom presentation, duration, and severity from endemic coronavirus infections in children. We compared symptom risk and duration of endemic human coronavirus (HCoV) infections from 2011–2016 with SARS-CoV-2 infections from March 2020-September 2021 in a Nicaraguan pediatric cohort. Blood samples were collected from study participants annually in February-April. Respiratory samples were collected from participants that met testing criteria. Blood samples collected in were tested for SARS-CoV-2 antibodies and a subset of 2011–2016 blood samples from four-year-old children were tested for endemic HCoV antibodies. Respiratory samples were tested for each of the endemic HCoVs from 2011–2016 and for SARS-CoV-2 from 2020–2021 via rt-PCR. By April 2021, 854 (49%) cohort participants were ELISA positive for SARS-CoV-2 antibodies. Most participants had antibodies against one alpha and one beta coronavirus by age four. We observed 595 symptomatic endemic HCoV infections from 2011–2016 and 121 symptomatic with SARS-CoV-2 infections from March 2020-September 2021. Symptom presentation of SARS-CoV-2 infection and endemic coronavirus infections were very similar, and SARS-CoV-2 symptomatic infections were as or less severe on average than endemic HCoV infections. This suggests that, for children, SARS-CoV-2 may be just another endemic coronavirus. However, questions about the impact of variants and the long-term effects of SARS-CoV-2 remain.

Individual-level Association of Influenza Infection With Subsequent Pneumonia: A Case-control and Prospective Cohort Study

BACKGROUND

Pneumonia is a leading cause of mortality worldwide. Influenza may result in primary pneumonia or be associated with secondary bacterial pneumonia. While the association with secondary pneumonia has been established ecologically, individual-level evidence remains sparse and the risk period for pneumonia following influenza poorly defined.

METHODS

We conducted a matched case-control study and a prospective cohort study among Nicaraguan children aged 0-14 years from 2011 through 2018. Physicians diagnosed pneumonia cases based on Integrated Management for Childhood Illness guidelines. Cases were matched with up to 4 controls on age (months) and study week. We fit conditional logistic regression models to assess the association between influenza subtype and subsequent pneumonia development, and a Bayesian nonlinear survival model to estimate pneumonia hazard following influenza.

RESULTS

Participants with influenza had greater risk of developing pneumonia in the 30 days following onset compared to those without influenza (matched odds ratio [mOR], 2.7 [95% confidence interval {CI}, 1.9-3.9]). Odds of developing pneumonia were highest for participants following A(H1N1)pdm09 illness (mOR, 3.7 [95% CI, 2.0-6.9]), followed by influenza B and A(H3N2). Participants' odds of pneumonia following influenza were not constant, showing distinct peaks 0-6 days (mOR, 8.3 [95% CI, 4.8-14.5] days) and 14-20 (mOR, 2.5 [95% CI, 1.1-5.5] days) after influenza infection.

CONCLUSIONS

Influenza is a significant driver of both primary and secondary pneumonia among children. The presence of distinct periods of elevated pneumonia risk in the 30 days following influenza supports multiple etiological pathways.

An immune correlate of SARS-CoV-2 infection and severity of reinfections

Background

An immune correlate of protection from SARS-CoV-2 infection is urgently needed.

Methods

We used an ongoing household cohort with an embedded transmission study that closely monitors participants regardless of symptom status. Real-time reverse-transcription polymerase chain reaction (RT-PCR) and Enzyme-linked immunosorbent assays (ELISAs) were used to measure infections and seropositivity. Sequencing was performed to determine circulating strains of SARS-CoV-2. We investigated the protection associated with seropositivity resulting from prior infection, the anti-spike antibody titers needed for protection, and we compared the severity of first and second infections.

Results

In March 2021, 62.3% of the cohort was seropositive. After March 2021, gamma and delta variants predominated. Seropositivity was associated with 69.2% protection from any infection (95% CI: 60.7%-75.9%), with higher protection against moderate or severe infection (79.4%, 95% CI: 64.9%-87.9%). Anti-spike titers of 327 and 2,551 were associated with 50% and 80% protection from any infection; titers of 284 and 656 were sufficient for protection against moderate or severe disease. Second infections were less severe than first infections (Relative Risk (RR) of moderated or severe disease: 0.6, 95% CI: 0.38-0.98; RR of subclinical disease:1.9, 95% CI: 1.33-2.73).

Conclusions

Prior infection-induced immunity is protective against infection when predominantly gamma and delta SARS-CoV-2 circulated. The protective antibody titers presented may be useful for vaccine policy and control measures. While second infections were somewhat less severe, they were not as mild as ideal. A strategy involving vaccination will be needed to ease the burden of the SARS-CoV-2 pandemic.

Dengue and Zika virus infections in children elicit cross-reactive protective and enhancing antibodies that persist long term

[Figure: see text].

Influenza Illness and Partial Vaccination in the First Two Years of Life

More information about influenza in low- and middle-income countries could guide the establishment of pediatric influenza vaccine programs. This study (1) characterizes the burden of influenza in infants, and (2) compares signs and symptoms by prior influenza vaccination or influenza illness. Newborns from Managua, Nicaragua, were followed for two years. Data came from primary medical appointments, PCR testing, and parents’ daily symptom diaries. Logistic regression models estimated associations between preceding vaccination or illness and influenza incidence. Linear models compared duration of illness by prior vaccination or influenza illness. Among 833 infants, 31% had PCR-positive influenza, and 28% were vaccinated against influenza. Four (<0.5%) were fully vaccinated. Overall, influenza incidence was 21.0 (95% confidence interval (CI): 18.8, 23.2) per 100 person-years. Incidence was lower among those with prior influenza compared with those without preceding illness or vaccination (OR: 0.64, 95% CI: 0.44, 0.94). Partially vaccinated children had 1 day less fever than those without prior illness or vaccination (p = 0.049). A large proportion of children <2 years in Nicaragua contract influenza. Illness was attenuated for those partially vaccinated. Since few children were fully vaccinated, future studies will need to consider the effectiveness of a two-dose vaccination schedule.

Symptoms, Infection Duration, and Hemagglutinin Inhibition Antibody Response in Influenza A Infections

BACKGROUND

Many influenza studies assume that symptomatic and asymptomatic cases have equivalent antibody responses.

METHODS

This study examines the relationship between influenza symptoms and serological response. Influenza-positive index cases and household members in Managua, Nicaragua, during 2012-2017 were categorized by symptom status.

RESULTS

Antibody response was assessed using hemagglutination inhibition assays (HAI). Among 510 cases, 74.5% had ≥4-fold increase in HAI antibodies, and 75.3% had febrile illness. In a logistic regression model, febrile cases had 2.17 times higher odds of a ≥4-fold titer rise compared to asymptomatic cases (95% confidence interval, 1.02-4.64).

CONCLUSIONS

Studies relying on serological assays may not generalize to asymptomatic infections.

Pre-existing Antineuraminidase Antibodies Are Associated With Shortened Duration of Influenza A(H1N1)pdm Virus Shedding and Illness in Naturally Infected Adults

Background

Influenza causes a substantial burden worldwide, and current seasonal influenza vaccine has suboptimal effectiveness. To develop better, more broadly protective vaccines, a more thorough understanding is needed of how antibodies that target the influenza virus surface antigens, hemagglutinin (HA) (including head and stalk regions) and neuraminidase (NA), impact influenza illness and virus transmission.

Methods

We used a case-ascertained, community-based study of household influenza virus transmission set in Managua, Nicaragua. Using data from 170 reverse transcriptase–polymerase chain reaction (RT-PCR)–confirmed influenza virus A(H1N1)pdm infections and 45 household members with serologically confirmed infection, we examined the association of pre-existing NA, hemagglutination inhibiting, and HA stalk antibody levels and influenza viral shedding and disease duration using accelerated failure time models.

Results

Among RT-PCR–confirmed infections in adults, pre-existing anti-NA antibody levels ≥40 were associated with a 69% (95% confidence interval [CI], 34–85%) shortened shedding duration (mean, 1.0 vs 3.2 days). Neuraminidase antibody levels ≥80 were associated with further shortened shedding and significantly shortened symptom duration (influenza-like illness, 82%; 95% CI, 39–95%). Among RT-PCR–confirmed infections in children, hemagglutination inhibition titers ≥1:20 were associated with a 32% (95% CI, 13–47%) shortened shedding duration (mean, 3.9 vs 6.0 days).

Conclusions

Our results suggest that anti-NA antibodies play a large role in reducing influenza illness duration in adults and may impact transmission, most clearly among adults. Neuraminidase should be considered as an additional target in next-generation influenza virus vaccine development.

We found that antibodies against neuraminidase were associated with significantly shortened viral shedding, and among adults they were also associated with shortened symptom duration. These results support neuraminidase as a potential target of next-generation influenza virus vaccines.

Pneumonia following symptomatic influenza infection among Nicaraguan children before and after introduction of the pneumococcal conjugate vaccine

Influenza is associated with primary viral and secondary bacterial pneumonias; however, the dynamics of this relationship in populations with varied levels of pneumococcal vaccination remain unclear. We conducted nested matched case-control studies in two prospective cohorts of Nicaraguan children aged 2-14 years: one before PCV introduction (2008-2010) and one following its introduction and near universal adoption (2011-2018). The association between influenza and pneumonia was similar in both cohorts. Participants with influenza (across types/subtypes) had higher odds of developing pneumonia in the month following influenza infection. These findings underscore the importance of considering influenza in interventions to reduce global pneumonia burden.

Zika virus infection enhances future risk of severe dengue disease

The Zika pandemic sparked intense interest in whether immune interactions among dengue virus serotypes 1 to 4 (DENV1 to -4) extend to the closely related Zika virus (ZIKV). We investigated prospective pediatric cohorts in Nicaragua that experienced sequential DENV1 to -3 (2004 to 2015), Zika (2016 to 2017), and DENV2 (2018 to 2020) epidemics. Risk of symptomatic DENV2 infection and severe disease was elevated by one prior ZIKV infection, one prior DENV infection, or one prior DENV infection followed by one ZIKV infection, compared with being flavivirus-naïve. By contrast, multiple prior DENV infections reduced dengue risk. Further, although high preexisting anti-DENV antibody titers protected against DENV1, DENV3, and ZIKV disease, intermediate titers induced by previous ZIKV or DENV infection enhanced future risk of DENV2 disease and severity, as well as DENV3 severity. The observation that prior ZIKV infection can modulate dengue disease severity like a DENV serotype poses challenges to development of dengue and Zika vaccines.

Association Between the Respiratory Microbiome and Susceptibility to Influenza Virus Infection

BACKGROUND

Previous studies suggest that the nose/throat microbiome may play an important role in shaping host immunity and modifying the risk of respiratory infection. Our aim is to quantify the association between the nose/throat microbiome and susceptibility to influenza virus infection.

METHODS

In this household transmission study, index cases with confirmed influenza virus infection and their household contacts were followed for 9-12 days to identify secondary influenza infections. Respiratory swabs were collected at enrollment to identify and quantify bacterial species via high-performance sequencing. Data were analyzed by an individual hazard-based transmission model that was adjusted for age, vaccination, and household size.

RESULTS

We recruited 115 index cases with influenza A(H3N2) or B infection and 436 household contacts. We estimated that a 10-fold increase in the abundance in Streptococcus spp. and Prevotella salivae was associated with 48% (95% credible interval [CrI], 9-69%) and 25% (95% CrI, 0.5-42%) lower susceptibility to influenza A(H3N2) infection, respectively. In contrast, for influenza B infection, a 10-fold increase in the abundance in Streptococcus vestibularis and Prevotella spp. was associated with 63% (95% CrI, 17-83%) lower and 83% (95% CrI, 15-210%) higher susceptibility, respectively.

CONCLUSIONS

Susceptibility to influenza infection is associated with the nose/throat microbiome at the time of exposure. The effects of oligotypes on susceptibility differ between influenza A(H3N2) and B viruses. Our results suggest that microbiome may be a useful predictor of susceptibility, with the implication that microbiome could be modulated to reduce influenza infection risk, should these associations be causal.

Obesity is associated with increased susceptibility to influenza A (H1N1pdm) but not H3N2 infection

BACKGROUND

Obesity has been shown to increase the risk of severe outcomes and death for influenza virus infections. However, we don't understand the influence of obesity on susceptibility to infection or on non-severe influenza outcomes.

METHODS

We performed a case-ascertained, community-based study of influenza transmission within households in Nicaragua. To investigate whether obesity increases the likelihood of influenza infection and symptomatic infection we use logistic regression models.

RESULTS

Between 2015 and 2018, a total of 335 index cases with influenza A and 1,506 of their household contacts were enrolled. Obesity was associated with increased susceptibility to symptomatic H1N1pdm infection among adults (OR: 2.10, 95%CI: 1.08-4.06), but not children, and this association increased with age. Among adults with H1N1pdm infection, obesity was associated with increased likelihood of symptoms (OR: 3.91, 95%CI: 1.55-9.87). For middle aged and older adults with obesity there was also a slight increase in susceptibility to any H1N1pdm infection (OR: 1.20, 95%CI: 0.62-2.34). Body Mass Index (BMI) was also linearly associated with increased susceptibility to symptomatic H1N1pdm infection, primarily among middle aged and older adult women (5-unit BMI increase OR: 1.40, 95%CI: 1.00-1.97). Obesity was not associated with increased H3N2 susceptibility or associated symptoms.

CONCLUSIONS

We found that among adults obesity is associated with susceptibility to H1N1pdm infection and with symptoms associated with H1N1pdm infection, but not with susceptibility to H3N2 infection or associated symptoms. These findings will help target prevention efforts and therapeutics to this high-risk population.

Assessing the Incidence of Symptomatic Respiratory Syncytial Virus Illness Within a Prospective Birth Cohort in Managua, Nicaragua

BACKGROUND

Respiratory syncytial virus (RSV) causes substantial morbidity and mortality among children worldwide, commonly through acute lower respiratory tract infections (ALRI). To assess the incidence rate of symptomatic RSV illness among young children, we conducted a prospective birth cohort study following children from 0-2 years of age in Managua, Nicaragua.

METHODS

Children meeting the testing criteria (fever, history of fever, or severe respiratory symptoms [apnea, stridor, nasal flaring, wheezing, chest indrawing, and/or central cyanosis]) were tested for RSV infections using real-time reverse transcriptase-polymerase chain reaction. An acute lower respiratory infection was defined as a diagnosis of pneumonia, bronchiolitis, bronchitis, or bronchial hyperreactivity. The incidence rate was calculated, and 95% confidence intervals were estimated using a Poisson distribution.

RESULTS

A total of 833 children participated in the cohort: 289 (34.7%) had at least 1 episode of laboratory-confirmed RSV, and 156 (18.7%) of had an episode of RSV-associated ALRI (RSV-ALRI). The incidence rate of symptomatic RSV was 248.1 cases per 1000 person-years (95% confidence interval [CI] 223.2-275.7). While infants aged 6-11 months had the highest incidence of symptomatic RSV (361.3/1000 person-years, 95% CI 304.4-428.8), infants <3 months had the highest incidence of severe RSV (RSV-associated hospitalizations and/or severe ALRI). RSV was also associated with 25.0-37.5% of deaths from medical causes (n = 8).

CONCLUSIONS

A substantial burden of RSV exists among children aged <2 years in Nicaraguan communities. RSV was also a leading cause of infant mortality among study participants. The development and implementation of effective RSV prevention and treatment measures represent an opportunity to substantially reduce severe illness and death among children worldwide.

Age-dependent manifestations and case definitions of paediatric Zika: a prospective cohort study

BACKGROUND

Paedeatric Zika remains an understudied topic. WHO and the Pan American Health Organization (PAHO) Zika case definitions have not been assessed in children. We aimed to characterise clinical profiles and evaluate the diagnostic performance of the WHO and PAHO case definitions in a large cohort of paediatric Zika cases.

METHODS

From January, 2016 to February, 2017, encompassing the major 2016 Zika epidemic, participants in the Pediatric Dengue Cohort Study (PDCS) in Managua, Nicaragua, were encouraged to visit the study health centre at first indication of any illness. PDCS participants were aged 2-14 years, healthy at enrolment, and recruited before the initiation of the present study. Molecular and serological assays were used to test participants exhibiting any of four broad clinical profiles suspected of resulting from a symptomatic Zika virus infection. These clinical profiles were: fever and at least two of headache, retro-orbital pain, myalgia, arthralgia, rash, haemorrhagic manifestations, and leukopenia; fever and at least two of nausea or vomiting, rash, aches and pains, positive tourniquet test, leukopenia, and any dengue warning sign; undifferentiated fever without evident cause, with or without any other clinical finding; and afebrile rash with or without any other clinical finding. We characterised acute clinical findings (signs, symptoms, and complete blood counts) in both Zika cases and non-Zika cases.

FINDINGS

We prospectively followed a cohort of about 3700 children, of which 1110 were deemed eligible for inclusion. Four participants with laboratory-confirmed Zika (three co-infections with dengue virus, one missing complete blood count data) and two participants who were non-Zika cases (missing complete blood count data) were excluded from analysis. We analysed 556 laboratory-confirmed Zika and 548 non-Zika cases. The WHO case definition captured 176 confirmed Zika cases, and the PAHO definition 109 confirmed Zika cases, who presented with the most clinical findings and a dengue-like clinical profile. The remaining two thirds of Zika cases, principally characterised by undifferentiated fever or afebrile rash, were missed. Among Zika cases, rash (n=440)-particularly generalised erythematous rash (n=334)-fever (n=333), leukopenia (n=217), and headache (n=203) were most common and peaked within 3 days of illness onset. The most common Zika presentation over the first week of illness was rash only (n=80). The sensitivity of Zika case definitions increased across paediatric age (from 11·3% to 56·1% for the WHO case definition and from 6·0% to 36·6% for the PAHO case definition), as the prevalence of most clinical findings (particularly arthralgia) increased with age, irrespective of previous dengue virus infection. Consequently, Zika manifested differently across paediatric age; older Zika cases presented with a dengue-like clinical profile while younger Zika cases presented with undifferentiated fever or afebrile rash.

INTERPRETATION

We provide the most thorough description of paediatric Zika to date. Most paediatric Zika cases go undetected under the WHO and PAHO case definitions, suggesting that current standards for Zika case ascertainment require revision. Zika manifests with mild but differing clinical profiles across paediatric age, presenting major challenges to diagnosis, surveillance, and efforts to control future Zika epidemics.

FUNDING

US National Institutes of Health.

Obesity Increases the Duration of Influenza A Virus Shedding in Adults

Epidemiologic studies indicate that obesity increases the risk of severe complications and death from influenza virus infections, especially in elderly individuals. This work investigates the effect of obesity on the duration of viral shedding within household transmission studies in Managua, Nicaragua, over 3 seasons (2015–2017). Symptomatic obese adults were shown to shed influenza A virus 42% longer than nonobese adults (adjusted event time ratio [ETR], 1.42; 95% confidence interval [CI], 1.06–1.89); no association was observed with influenza B virus shedding duration. Even among paucisymptomatic and asymptomatic adults, obesity increased the influenza A shedding duration by 104% (adjusted ETR, 2.04; 95% CI, 1.35–3.09). These findings suggest that obesity may play an important role in influenza transmission.

Influenza Transmission Dynamics in Urban Households, Managua, Nicaragua, 2012-2014

In this low-income country setting, ≈16% of household contacts acquired infections from index patients, despite high oseltamivir use.

During August 2012–November 2014, we conducted a case ascertainment study to investigate household transmission of influenza virus in Managua, Nicaragua. We collected up to 5 respiratory swab samples from each of 536 household contacts of 133 influenza virus–infected persons and assessed for evidence of influenza virus transmission. The overall risk for influenza virus infection of household contacts was 15.7% (95% CI 12.7%–19.0%). Oseltamivir treatment of index patients did not appear to reduce household transmission. The mean serial interval for within-household transmission was 3.1 (95% CI 1.6–8.4) days. We found the transmissibility of influenza B virus to be higher than that of influenza A virus among children. Compared with households with <4 household contacts, those with >4 household contacts appeared to have a reduced risk for infection. Further research is needed to model household influenza virus transmission and design interventions for these settings.