Change in Body Mass Index in Youth in the First 5 Years After Type 1 Diabetes Mellitus Diagnosis.

OBJECTIVE: Examine body mass index (BMI) trajectories in American youth with type 1 diabetes (T1D) over the first 5 years following diagnosis. METHODS: Retrospective record review of BMI trajectories in youth with T1D diagnosed in 2015 to 2016. RESULTS: Near the time of diabetes diagnosis, 35.5% of youth had BMIs in the overweight/obesity range. These rates increased over time (P < .001), with 52.8% having overweight/obesity 5 years after diagnosis. Average age when BMI rose from healthy to overweight/obese or overweight to obese (rise group) was at 12.7 years, occurring 2.5 years after diagnosis. There were no differences between hemoglobin A1c, use of continuous glucose monitors, or use of insulin pumps between the rise group and those with healthy BMI throughout the study period. CONCLUSIONS: Alarmingly high rates of overweight/obesity in youth were observed within 5 years following T1D diagnosis. Awareness and further research are necessary to address this independent risk factor for morbidities.

Validation of remote anthropometric measurements in a rural randomized pediatric clinical trial in primary care settings.

Rural children are more at risk for childhood obesity but may have difficulty participating in pediatric weight management clinical trials if in-person visits are required. Remote assessment of height and weight observed via videoconferencing may provide a solution by improving the accuracy of self-reported data. This study aims to validate a low-cost, scalable video-assisted protocol for remote height and weight measurements in children and caregivers. Families were provided with low-cost digital scales and tape measures and a standardized protocol for remote measurements. Thirty-three caregiver and child (6-11 years old) dyads completed remote (at home) height and weight measurements while being observed by research staff via videoconferencing, as well as in-person measurements with research staff. We compared the overall and absolute mean differences in child and caregiver weight, height, body mass index (BMI), and child BMI adjusted Z-score (BMIaz) between remote and in-person measurements using paired samples t-tests and one sample t-tests, respectively. Bland-Altman plots were used to estimate the limits of agreement (LOA) and assess systematic bias. Simple regression models were used to examine associations between measurement discrepancies and sociodemographic factors and number of days between measurements. Overall mean differences in child and caregiver weight, height, BMI, and child BMIaz were not significantly different between remote and in-person measurements. LOAs were - 2.1 and 1.7 kg for child weight, - 5.2 and 4.0 cm for child height, - 1.5 and 1.7 kg/m2 for child BMI, - 0.4 and 0.5 SD for child BMIaz, - 3.0 and 2.8 kg for caregiver weight, - 2.9 and 3.9 cm for caregiver height, and - 2.1 and 1.6 kg/m2 for caregiver BMI. Absolute mean differences were significantly different between the two approaches for all measurements. Child and caregiver age were each significantly associated with differences between remote and in-person caregiver height measurements; there were no significant associations with other measurement discrepancies. Remotely observed weight and height measurements using non-research grade equipment may be a feasible and valid approach for pediatric clinical trials in rural communities. However, researchers should carefully evaluate their measurement precision requirements and intervention effect size to determine whether remote height and weight measurements suit their studies.Trial registration: ClinicalTrials.gov NCT04142034 (29/10/2019).

Persistent hypercalcemia mimicking hypophosphatasia after discontinuation of a ketogenic diet: a case report.

OBJECTIVES: Hypercalcemia has been reported as an uncommon complication of the ketogenic diet (KD). Here we present a toddler whose hypercalcemia persisted for 2 months after stopping the KD. CASE PRESENTATION: A 2 year 11-month-old child with global developmental delay, infantile spasms, neuromuscular weakness with limited mobility, tracheostomy and ventilator dependence, and oropharyngeal dysphagia with G-tube dependence presented with hypercalcemia in the setting of recurrent vomiting. At presentation, the patient was adherent to a KD and taking topiramate since infancy for intractable seizures. His laboratory parameters at presentation showed hypercalcemia (11.9 mg/dL), hypercalciuria, acute renal failure, low alkaline phosphatase (76 IU/L [110-302 IU/L]), parathyroid hormone (PTH) <6 pg/mL (18-80 pg/mL), normal thyroid function, cortisol and vitamin D level. The patient's hypercalcemia persisted post-discontinuation of the KD and topiramate. PTH-related protein was mildly elevated at 15.3 pmol/L. Follow-up laboratory and imaging studies ruled out malignancy. He was managed with calcitonin 4 u/kg/dose Q12H × 1 day and 8 u/kg/dose Q8H × 1 day, hydration and low-calcium formula. Post-discontinuation of the KD, normalization of alkaline phosphatase levels preceded the normalization of calcium on day 55 and PTH on day 85. CONCLUSIONS: Hypercalcemia may persist for an extended period after weaning from a KD; lab parameters may mimic that of hypophosphatasia as previously described in the literature. Normalization of alkaline phosphatase, a marker of bone turnover, indicates recovery from the adynamic state induced by the KD and typically precedes the normalization of calcium and PTH.

A Case of Severe Neonatal Hypocalcemia Treated With Continuous Enteral Calcium.

Background/Objective: Hypocalcemia is a common, treatable cause of neonatal seizures. The rapid repletion of calcium is essential for restoring normal calcium homeostasis and resolving seizure activity. The accepted approach to administer calcium to a hypocalcemic newborn is via peripheral or central intravenous (IV) access. Case Report: We discuss a case of a 2-week-old infant who presented with hypocalcemia and status epilepticus. The etiology was determined to be neonatal hypoparathyroidism secondary to maternal hyperparathyroidism. Following an initial dose of IV calcium gluconate, the seizure activity abated. However, stable peripheral intravenous access could not be maintained. After weighing the risks and benefits of placing a central venous line for calcium replacement, it was decided to use continuous nasogastric calcium carbonate at a rate of 125 mg of elemental calcium/kg/d. Ionized calcium levels were used to guide the course of the therapy. The infant remained seizure-free and was discharged on day 5 on a treatment regimen that included elemental calcium carbonate, calcitriol, and cholecalciferol. He remained seizure free since discharge and all medications were discontinued by 8 weeks of age. Discussion: Continuous enteral calcium is an effective alternate therapy for restoration of calcium homeostasis in a neonate presenting with hypocalcemic seizures in the intensive care unit (ICU). Conclusion: We propose that continuous enteral calcium be considered as an alternative approach for calcium repletion in neonatal hypocalcemic seizures, one that avoids the potential complications of peripheral or central IV calcium administration.

Incidence, Severity, and Presentation of Type 2 Diabetes in Youth During the First and Second Year of the COVID-19 Pandemic.

OBJECTIVE: To describe the evolving impact of the coronavirus disease 2019 pandemic on the incidence and presentation of new-onset pediatric type 2 diabetes. RESEARCH DESIGN AND METHODS: Retrospective medical record review of youth with new-onset type 2 diabetes comparing the prepandemic period (1 January 2017-29 February 2020) with the first (1 March 2020-31 December 2020) and second pandemic year (1 January 2021-31 December 2021). RESULTS: The annualized incidence of type 2 diabetes increased nearly threefold during the pandemic versus prior, with a 61% increase in the 2nd versus 1st year. BMI increased during the pandemic versus prior (129% of 95th percentile vs. 141%, P = 0.02). In the 1st year, patients were younger (12.9 years vs. 14.8, P < 0.001), with higher incidence of diabetic ketoacidosis and/or hyperglycemic hyperosmolar syndrome (20% vs. 3.5%, P = 0.02) versus prior. CONCLUSIONS: Providers should be aware of the escalating incidence of youth-onset type 2 diabetes to avoid delays in diagnosis and inform educational programs to combat the continued impact of the pandemic on health outcomes.

Severe Hypothyroidism and Large Goiter due to Iodine Deficiency in an Adolescent Male in the United States: A Case Report and Review of the Literature.

Acquired hypothyroidism due to iodine deficiency is extremely rare in the United States due to the introduction of table salt iodization in the 1920s (Leung et al., 2012). We present the case of an adolescent male with a history of mild autism spectrum disorder and an extremely restrictive diet who was found to have iodine deficiency as the etiology for his rapidly enlarging goiter and antibody-negative hypothyroidism. Thyroid-stimulating hormone (TSH) was 416 µIU/mL (0.350-5.500 µIU/mL), free thyroxine (T4) was <0.1 ng/dL (0.80-1.80 ng/dL), and triiodothyronine (T3) was 41 ng/dL (82-213 mg/dL) at diagnosis. The patient's 24-hour urinary iodine was undetectable. He was started on iodine supplementation with rapid visible improvement of goiter within two weeks and normalization of thyroid function tests within four weeks. Thorough dietary history and nutritional screening are important in cases of acquired hypothyroidism and/or goiter. Alternatively, diets that are low in iodized salt, dairy, bread, and seafood should raise concern for iodine deficiency, and patients with suspected or proven iodine deficiency should be screened for hypothyroidism.

Pediatric stiff limb syndrome with polyautoimmunity of anti-GAD-65, anti-islet cell, and thyroid peroxidase antibodies: A case report and review of literature.

We report an early childhood onset Stiff Limb Syndrome (SLS) in association with unusual polyautoimmunity of GAD-65, anti-islet cell, and Thyroid Peroxidase (TPO) autoantibodies, who has achieved a nearly complete neurological recovery following combined immunotherapy, symptomatic and physical therapy. The patient had normal MRIs of the brain and spinal cord and a negative paraneoplastic work-up. Subsequently, she developed hypothyroidism requiring levothyroxine supplementation. We then conducted an extensive review of literature and identified 52 previously reported pediatric Stiff Man Syndrome (SMS)/Stiff Person Syndrome (SPS) or SLS cases, which has demonstrated a common association with other systemic autoimmune conditions. In the available literature, screening for concurrent autoimmunity has only been reported infrequently. We found that a paraneoplastic process is extremely rare in pediatric cases. Timely diagnosis and initiation of immunotherapy are critical to a favorable outcome. Therefore, we recommend to include SMS/SPS or SLS as an important differential diagnosis for MRI-negative myelopathy. Further clinical and research efforts should be focused on understanding the role of both genetic predisposition and environmental insults in the autoimmunity of pediatric SMS/SPS or SLS.

Low Adrenomedullary Function Predicts Acute Illness in Infants With Classical Congenital Adrenal Hyperplasia.

CONTEXT: Youth with classical congenital adrenal hyperplasia (CAH) exhibit abnormal adrenomedullary function with decreased epinephrine levels noted in newborns and young infants. Little is known about how this relates to morbidity during the first year of life. OBJECTIVE: This work aimed to study plasma epinephrine levels in infants with classical CAH and examine the clinical significance of epinephrine deficiency in the first year of life. METHODS: This prospective cohort study comprised participants recruited from a pediatric tertiary care center: 36 infants with classical CAH due to 21-hydroxylase deficiency and 27 age-matched unaffected controls with congenital hypothyroidism. Main outcome measures included plasma epinephrine levels (N = 27), CYP21A2 genotype (N = 15), and incidence of acute illnesses from birth to age 1 year (N = 28). RESULTS: Epinephrine levels in CAH infants independently predicted illness incidence in the first year of life (ß = -0.018, R = -0.45, P = .02) and were negatively correlated with 17-hydroxyprogesterone at diagnosis (R = -0.51, P = .007). Infants with salt-wasting CAH exhibited lower epinephrine levels as newborns than simple-virilizing infants (P = .02). CAH patients had lower epinephrine as newborns than did controls (P = .007) and showed decreases in epinephrine from birth to age 1 year (P = .04). Null genotype was associated with lower newborn epinephrine and more illness in the first year of life, compared to less severe mutation categories. CONCLUSION: Lower epinephrine levels are associated with increased risk of illness among CAH infants. While not currently part of clinical standard of care, measuring epinephrine levels and assessing genotype may help predict acute illness in the first year of life.

Developmental Changes in Food Perception and Preference.

Food choices are a key determinant of dietary intake, with brain regions, such as the mesolimbic and prefrontal cortex maturing at differential rates into adulthood. More needs to be understood about developmental changes in healthy and unhealthy food perceptions and preference. We investigated how food perceptions and preference vary as a function of age and how food attributes (taste and health) impact age-related changes. One hundred thirty-nine participants (8-23 years, 60 females) completed computerized tasks to rate high-calorie and low-calorie food cues for taste, health, and liking (preference), followed by 100 binary food choices based on each participant's ratings. Dietary self-control was considered successful when the healthier (vs. tastier) food was chosen. Self-control success ratio was the proportion of success trials over total number of choices. Beta-weights for health (ß-health) and taste (ß-taste) were calculated as each attribute's influence on food preference. Adiposity measurements included BMI z-score and waist-to-height ratio (WHtR). High-calorie foods were rated more tasty and less healthy with increasing age. Older participants liked high-calorie foods more (vs. younger participants), and ß-taste was associated with age. Significant age-by-WHtR interactions were observed for health and taste ratings of high-calorie foods, ß-taste, and marginally for preference of high-calorie foods. Stratifying by WHtR (high, low), we found age-related increases in taste and preference ratings of high-calorie foods in the high WHtR group alone. In contrast, age-related decreases in health ratings of high-calorie foods were significant in the low WHtR group alone. Age and ß-taste were significantly associated in the high WHtR group and only marginally significant with low WHtR. Although participants rated low-calorie foods as less tasty and less healthy with increasing age, there was no association between age and preference for low-calorie foods. Participants made faster food choices with increasing age regardless of WHtR, with a significant age-by-WHtR interaction on reaction time (RT). There were no age-related effects in self-control success ratio and ß-health. These results suggest that individual differences in age and central adiposity play an important role in preference for high-calorie foods, and a higher importance of food tastiness in food choice may contribute to greater preference for high-calorie foods with increasing age.

Obesity-related asthma in children: A role for vitamin D.

Excess adipose tissue predisposes to an enhanced inflammatory state and can contribute to the pathogenesis and severity of asthma. Vitamin D has anti-inflammatory properties and low-serum levels are seen in children with asthma and in children with obesity. Here we review the intersection of asthma, obesity, and hypovitaminosis D in children. Supplementation with vitamin D has been proposed as a simple, safe, and inexpensive adjunctive therapy in a number of disease states. However, little research has examined the pharmacokinetics of vitamin D and its therapeutic potential in children who suffer from obesity-related asthma.

No evidence for a difference in 2D:4D ratio between youth with elevated prenatal androgen exposure due to congenital adrenal hyperplasia and controls.

The second-to-fourth digit ratio (2D:4D) has been associated with sexual dimorphism, with a lower 2D:4D in males. A large body of research has relied on the 2D:4D as a proxy for prenatal androgen exposure, and includes reports of relationships between 2D:4D and a wide range of human traits. Here, we examine the validity of the 2D:4D proxy by studying the association between 2D:4D and classical Congenital Adrenal Hyperplasia (CAH) due to 21-hydroxylase deficiency, a condition characterized by excessive prenatal exposure to androgens during most of the gestational period. To this end, we retrospectively examine 513 serial radiographs of the left hand obtained clinically in 90 youth with classical CAH (45 female) and 70 control youth (31 female). Replicating previous reports, we observe associations of the 2D:4D with sex (lower 2D:4D in males) and age (increase of 2D:4D through development). However, we find no evidence for differences in 2D:4D between CAH and controls (full sample: ß = -0.001 (-0.008, 0.006); females: ß = -0.004 [-0.015, 0.007]; males: ß = 0.001, [-0.008, 0.011]). Although our findings do not rule out a small association between the 2D:4D and CAH, they cast doubt on the usefulness of the 2D:4D as a biomarker for prenatal androgen exposure in behavioral research.

Prefrontal Cortex and Amygdala Subregion Morphology Are Associated With Obesity and Dietary Self-control in Children and Adolescents.

A prefrontal control system that is less mature than the limbic reward system in adolescence is thought to impede self-regulatory abilities, which could contribute to poor dietary choices and obesity. We, therefore, aimed to examine whether structural morphology of the prefrontal cortex (PFC; involved in cognitive control) and the amygdala (a key brain region for reward-related processing) are associated with dietary decisions and obesity in children and adolescents. Seventy-one individuals between the ages of 8-22 years (17.35 ± 4.76 years, 51% female, 56% were overweight or obese) participated in this study; each participant completed a computer-based food choice task and a T1- and T2-weighted structural brain scans. Two indices of obesity were assessed, including age- and sex-specific body mass index (BMIz) and waist-to-height ratio (WHtR). The behavioral task included rating 60 food stimuli for tastiness, healthiness, and liking. Based on each participant's self-ratings, 100 binary food choices were then made utilizing a computer mouse. Dietary "self-control" was calculated as the proportion of trials where the individual chose the healthier food item (vs. the tastier food item) over the total number of trials. Cortical thickness and amygdala subnuclei volumes were quantified using FreeSurfer 6.0 and CIT168 atlas, respectively. We found that WHtR was negatively associated with the thickness of bilateral superior frontal, left superior temporal, right insula, and right inferior temporal regions (p < 0.05, corrected for multiple comparisons). We also found WHtR to be positively associated with the volume of the central nucleus (CEN) region of the amygdala (p = 0.006), after adjusting for the hemisphere, age, sex, and intracranial volumes. A similar data pattern was observed when BMIz was used. Moreover, we found that across all participants, thinner right superior frontal cortex and larger left CEN volumes predicted lower dietary self-control. These results suggest that differential development of the PFC and amygdala relate to obesity and dietary self-control. Further longitudinal studies are merited to determine causal relationships among altered PFC to amygdala neural circuitry, dietary self-control, and obesity.

Individualized care for patients with intersex (disorders/differences of sex development): Part 3.

The focus of this article is to review the complex determinants of gender assignment in a child with a disorder of sex development using four different clinical cases. While the care of patients with DSD may be shared across several specialties and opinions regarding their management may vary, this may be further complicated by psychosocial, cultural and economic factors. In this regard, access to behavioral health specialists with experience and specialization in the treatment of patients with DSD should be a foundational component of the standard of care and can greatly assist in the complex decision-making regarding gender assignment. We recommend an individualized approach by a multidisciplinary team utilizing a range of evolving strategies, including outcome data (or lack thereof) to support families during the decision-making process.

A germline mutation of HRPT2/CDC73 (70 G>T) in an adolescent female with parathyroid carcinoma: first case report and a review of the literature.

Parathyroid carcinoma is a rare cause of primary hyperparathyroidism amongst children, with only nine previously reported cases. The objective of the study was to present the first pediatric case with a germline CDC73 (formerly known as HRPT2) mutation, and to review the literature. A 14-year-old girl presented with pathologic slipped capital femoral epiphysis (SCFE). The patient was noted to have an elevated calcium level of 3.4 mmol/L (13.4 mg/dL), a parathyroid hormone (PTH) level of 1013 ng/L (1013 pg/mL), and a 3-cm palpable neck mass. Ultrasound and 99mTc-Sestamibi confirmed the suspicion of a parathyroid mass. Intraoperative findings and pathology confirmed the diagnosis of parathyroid carcinoma. Post-operative PTH decreased to 14 ng/L (14 pg/mL). Genetic testing showed a germline 70 G>T HRPT2/CDC73 mutation. This is the first case documenting a germline 70 G>T HRPT2/CDC73 gene mutation in a pediatric parathyroid carcinoma. Patients with sporadic parathyroid carcinoma may benefit from HRPT2/CDC73 gene mutation screening.

Association of Non-High-Density Lipoprotein Cholesterol with Psychosocial Dysfunction in Children and Adolescents with Obesity.

BACKGROUND: Children with obesity have worse psychosocial functioning compared to their non-overweight peers. Adult studies suggest that several metabolic factors may participate in the etiology of depression in obesity. METHODS: We evaluated the association of several metabolic parameters with psychosocial dysfunction in children with obesity, through a retrospective review of electronic medical records in patients ages 6-17. All parents were asked to complete the Pediatric Symptom Checklist (PSC) questionnaire, a validated measurement of psychosocial dysfunction in children. RESULTS: PSC scores were available in 618 patients. Overall, 11.2% of patients had a PSC score ≥28, suggestive of psychosocial dysfunction. Non-high-density lipoprotein (HDL) cholesterol was associated with a higher PSC score (p = 0.02), after adjusting for age, sex, race, socioeconomic status, and BMI z-score. CONCLUSIONS: Consistent with adult studies, in children and adolescents with obesity, non-HDL cholesterol may play a role in the etiology of psychosocial dysfunction. Further studies are warranted.

Association of ALT and the metabolic syndrome among Mexican children.

Nonalcoholic fatty liver disease (NAFLD) is emerging as a component of the metabolic syndrome (MetS); Hispanics being particularly predisposed. Alanine aminotransferase (ALT) is considered a marker of NAFLD. The aim of this study was to determine the prevalence and associations between ALT elevations and MetS in normal-weight, overweight and obese Mexican children and adolescents, since data in Mexico is scarce. Body mass index (BMI), waist circumference (WC), percentage body fat, blood pressure, glucose, lipid profiles, ALT and aspartate aminotransferase (AST) were measured in 236, 6-12yo normal-weight, overweight and obese Mexicans from eight public schools. The results showed that elevated ALT (>40 IU/L) was found in 17.7% of the obese and overweight population, with no gender difference. The prevalence of elevated ALT increased linearly across BMI categories (p = 0.001), from 0.0% for the normal-weight group (95%CI 0.0-€“8.0) to 22.4% for the obese one (95%CI 16.2-€“30.2). AST/ALT ratio <1 also increased linearly, as did the prevalence of MetS (p = 0.001), from 0.0% for the normal-weight group to 40.3% for the obese one. The prevalence of MetS was strongly associated with elevated ALT (p = 0.002), 50% in the elevated ALT group (95%CI 34.1-€“65.9) and 24.1% in the normal ALT one (95%CI 18.1-€“31.3). There was also a strong association between MetS and an AST/ALT ratio <1. WC was the best predictor of elevated ALT (AOR = 7.13). Pearson correlation showed that MetS components were significantly correlated with elevated ALT. Therefore elevated ALT levels were highly prevalent and strongly associated with MetS in Mexican children, it should be screened in overweight and obese children.

Activation of the ATM-Snail pathway promotes breast cancer metastasis.

The DNA damage response (DDR) is critical for the maintenance of genetic stability and serves as an anti-cancer barrier during early tumorigenesis. However, the role of the DDR in tumor progression and metastasis is less known. Here, we demonstrate that the ATM kinase, one of the critical DDR elements, is hyperactive in late stage breast tumor tissues with lymph-node metastasis and this hyperactivity correlates with elevated expression of the epithelial-mesenchymal transition marker, Snail. At the molecular level, we demonstrate that ATM regulates Snail stabilization by phosphorylation on Serine-100. Using mass spectrometry, we identified HSP90 as a critical binding protein of Snail in response to DNA damage. HSP90 binds to and stabilizes phosphorylated Snail. We further provide in vitro and in vivo evidence that activation of ATM-mediated Snail phosphorylation promotes tumor invasion and metastasis. Finally, we demonstrate that Snail Serine-100 phosphorylation is elevated in breast cancer tissues with lymph-node metastasis, indicating clinical significance of the ATM-Snail pathway. Together, our findings provide strong evidence that the ATM-Snail pathway promotes tumor metastasis, highlighting a previously undescribed role of the DDR in tumor invasion and metastasis.

Clinical and epidemiological features of 2009 pandemic H1N1 influenza differ slightly according to seroprevalence status during the second wave in the general population in México.

BACKGROUND: Clinical features of pandemic H1N1 have been derived from lab-confirmed, hospitalized, or critically ill subjects. This report describes the clinical features of H1N1 and their prevalence from non-confirmed subjects according to seroprevalence status in México. The objective was to determine the prevalence of these clinical features from non-confirmed cases of pandemic H1N1 and to compare them according to seroprevalence status in northern Monterrey, México, during 2009, and to identify the predictive signs and symptoms; there have been no prior serologic studies in México. METHODS: During November-December 2009, 2,222 volunteers, ages 6-99 years, were categorized into 3 symptomatic groups: influenza-like illness, respiratory illness, and non-respiratory illness. Antibodies against influenza A/H1N1/2009 were determined by a virus-free enzyme-linked immunosorbent assay (ELISA) method. Demographics and clinical presentation were assessed through face-to-face questionnaire, and the association with seroprevalence status was determined and compared. RESULTS: Overall seroprevalence was 39%. Of the seropositive subjects, 67% were symptomatic and 33% were asymptomatic. Seventy-one percent of seropositive symptomatic subjects reported respiratory illness, 17% reported non-respiratory symptoms, and 12% reported influenza-like illness. The most common symptoms were rhinorrhea/nasal congestion (93%) and headache (83%). No significant difference was found between the symptom profiles of the seropositive group, compared to the seronegative one, nor of the median duration of symptoms. The seropositive group had a significantly elevated proportion of influenza-like illness (12%), compared to the seronegative group (8%). The proportion of subjects who took days off and who sought medical attention was significantly higher in the seropositive group. No single symptom was associated as a predictor of seropositiveness. CONCLUSIONS: One third of the seropositive subjects were asymptomatic, and few had an influenza-like illness. No difference was found in the symptom profiles of the seropositive and seronegative groups. No single symptom predicted seropositiveness. Large scale population studies are needed, especially in México, to characterize clinical syndromes.