Diagnostic testing for galactose-alpha-1,3-galactose,United States, 2010 to 2018

BackgroundAlpha-gal syndrome (AGS) is an emerging immunoglobulin E (IgE)–mediated allergy to galactose-alpha-1,3-galactose (alpha-gal). The geographic distribution and burden of AGS in the United States are unknown.ObjectiveTo characterize alpha-gal IgE testing patterns and describe the trends and distribution from 2010 to 2018 in the United States.MethodsThis retrospective analysis included all persons tested for alpha-gal IgE antibodies by Viracor-IBT Laboratories (Lee’s Summit, Missouri), the primary site of testing in the United States. Data included age and sex of person tested, specimen state of origin, collection date, and result value; persons with at least 1 positive test result (≥0.1 kU/L) were compared with negatives. Proportions tested and with positive test results were calculated using the US Census population estimates.ResultsOverall, 122,068 specimens from 105,674 persons were tested for alpha-gal IgE during July 1, 2010, to December 31, 2018. Nearly one-third (34,256, 32.4%) had at least 1 positive result. The number of persons receiving positive test results increased 6-fold from 1110 in 2011 to 7798 in 2018. Of those receiving positive test results, mean [SD] age was 46.9 (19.8) years; men were more likely to test positive than women (43.3% vs 26.0%). Arkansas, Virginia, Kentucky, Oklahoma, and Missouri had the highest number of persons who were tested and had a positive result per 100,000 population.ConclusionMore than 34,000 persons, most presumably symptomatic, have received positive test results for IgE antibodies to alpha-gal, suggesting AGS is an increasingly recognized public health problem. The geographic distribution of persons who tested positive is consistent with exposure to Amblyomma americanum ticks.     

Vascular biomarkers in the prediction of clinical cardiovascular disease: the Strong Heart Study

We compared the ability of separately measured intimal-medial thickness and atherosclerotic plaque to predict incident cardiovascular disease. American Indian men and women from the Strong Heart Study who were free of cardiovascular disease were evaluated with carotid ultrasound and cardiovascular disease risk factor assessment. End-diastolic intimal-medial thickness of the common carotid arteries was measured and averaged. Arterial mass (cross-sectional area) was calculated from intimal-medial thickness and end-diastolic diameter. Atherosclerosis was defined by focal plaque (discrete thickening >50% relative to the adjacent wall) and the number of carotid segments containing plaque (plaque score); 2441 participants (age 63±8 years) were followed-up for a mean of 7.7±2.8 years, during which time 495 experienced incident cardiovascular disease events. Time-to-event analyses were performed in groups stratified according to diabetes and hypertension status. Cardiovascular disease events were predicted by presence and extent of atherosclerosis in all groups; intima-medial thickness and arterial mass were only associated with outcomes when neither hypertension nor diabetes was present. Unequivocal evidence of atherosclerosis (plaque) and its extent (plaque score) are independently associated with incident cardiovascular disease events in individuals without preexisting cardiovascular disease regardless of diabetes and hypertension status. Hypertension-related increases in intima-media thickness and arterial mass appear to limit their use as measures of early or diffuse atherosclerosis and, hence, association with cardiovascular disease outcomes. These findings support the utility of separate assessment of focal atherosclerosis and intimal-medial thickness in epidemiological studies, trials, and risk stratification protocols.     

Physical activity and telomere length in American Indians: the Strong Heart Study

Telomere length, a marker of biological aging, has been associated with many chronic diseases, but its relations with physical activity remains unclear. The purpose of this study was to examine the association of objectively measured ambulatory activity with leukocyte telomere length (LTL), a marker of biological aging, among American Indians. This cross-sectional study included 2312 AI participants from the Strong Heart Family Study. Steps per day were measured using Accusplit AE120 pedometers. Quantitative PCR was used to measure LTL. Generalized estimating equations were used to examine the associations of steps per day with LTL. The median steps per day over a 1 week period was 5118 steps (interquartile range = 3163–7576 steps). Compared to participants in the lowest quartile of steps per day, participants in the upper three quartiles of steps per day had longer LTL: beta ± SE = 0.0195 ± 0.0144, 0.0273 ± 0.0139, and 0.0375 ± 0.0143 T/S ratio units longer (p trend = 0.010) after adjustment for potential confounders. These data suggest that ambulatory activity is associated with LTL. Further studies are needed to determine the mechanism by which ambulatory activity influences LTL.     

Blastomycosis of bones and joints

A retrospective study of 45 patients hospitalized with blastomycosis of bones or joints revealed 41 cases of osteomyelitis and 12 cases of septic arthritis. The majority were men (35 [78%] patients) and non-Aboriginal (32 [71%] patients). Median time from the onset of symptoms to hospitalization was shorter in women than men (male, 48 d; female, 14 d; P < 0.02), and shorter for Aboriginals than non-Aboriginals (non-Aboriginal, 50 d; Aboriginal, 19 d; P < 0.04). Cutaneous disease was present in 33 (73%) patients, and lung involvement was present in 29 (64%) patients. The most common osseous sites of involvement were the lower limb and axial skeleton. Common orthopaedic symptoms of bone lesions included bone pain in 42 (78%) patients, swelling in 32 (59%) patients, and soft tissue abscesses in 21 (39%) patients. Joint infection (12 patients) manifested as a monoarticular arthropathy presenting with effusion in 9 (75%) patients, pain in 8 (67%) patients, and decreased range of motion in 5 (42%) patients. Osseous blastomycosis can mimic bacterial infection and should be included in the differential diagnosis of bone and joint infection in patients who have visited or who live in geographic regions where B dermatitidis is endemic.