1214. Household Transmission of Febrile Illness Measured by Smartphone-Connected Thermometers, United States, 2016-2021

Background

Understanding household transmission dynamics of infectious diseases can help develop mitigation strategies. Traditional methods of population-level disease surveillance do not capture household transmission. Data collected from smartphone-connected thermometers that can differentiate among individuals in a household can be used to study these characteristics. Using this technology, we estimated the household secondary attack rate (SAR) of febrile illness, assessed its correlation with CDC-reported influenza-like illness (ILI) and COVID-19 case incidence, and identified risk factors for secondary transmission.

Methods

We conducted a retrospective cohort study among 596,096 febrile illness index cases recorded from August 1, 2016 to January 20, 2021 in households with two or more individuals in all 50 states. Fevers were measured using the Kinsa Smart Thermometer and mobile device app. Secondary cases were defined as household members who recorded a fever 1–10 days after an index case. We calculated SAR prior to and during the COVID-19 pandemic within the study period, and assessed correlation to ILI and COVID-19 case incidence using Spearman’s rank correlation coefficient. Bivariate and multivariable mixed logistic regression models were used to identify risk factors for secondary transmission.

Results

SAR in the pre-COVID-19 period was 5.9% (95% CI: 5.8%–6.0%) during flu season (November to April), and 3.7% (95% CI: 3.6%–3.7%) in flu off-season, and weekly SAR was significantly correlated with ILI reported from CDC (ρ=0.84, p< 0.001). Secondary transmission was 40% more likely to occur in households where the index case’s initial temperature was ≥ 39.1°C. During the COVID-19 period, SAR was 3.3% (95% CI: 3.3%–3.4%), and daily SAR was significantly correlated with national daily COVID-19 incidence rates (ρ=0.86, p< 0.001). Households in census tracts with >50% essential workforce were 50% more likely to experience secondary transmission.

Conclusion

Household SAR was highly correlated with ILI and COVID-19 cases. Capturing household transmission of febrile illness through routine public health surveillance may identify risk factors for infectious disease transmission, allowing for more targeted interventions.

Disclosures

Danielle Bloch, MPH, Kinsa Health (Employee, Shareholder) John Zicker, MS, Kinsa Health (Employee, Shareholder) Hannah Somhegyi, PhD, Kinsa Health (Employee, Shareholder) Patrick Philips, n/a, Kinsa Health (Employee, Shareholder) Inder Singh, n/a, Kinsa Health (Board Member, Employee, Shareholder) Amy Daitch, PhD, Kinsa Health (Employee, Shareholder)

Function and regulation of the Caenorhabditis elegans Rab32 family member GLO-1 in lysosome-related organelle biogenesis

Cell type-specific modifications of conventional endosomal trafficking pathways lead to the formation of lysosome-related organelles (LROs). C. elegans gut granules are intestinally restricted LROs that coexist with conventional degradative lysosomes. The formation of gut granules requires the Rab32 family member GLO-1. We show that the loss of glo-1 leads to the mistrafficking of gut granule proteins but does not significantly alter conventional endolysosome biogenesis. GLO-3 directly binds to CCZ-1 and they both function to promote the gut granule association of GLO-1, strongly suggesting that together, GLO-3 and CCZ-1 activate GLO-1. We found that a point mutation in GLO-1 predicted to spontaneously activate, and function independently of it guanine nucleotide exchange factor (GEF), localizes to gut granules and partially restores gut granule protein localization in ccz-1(-) and glo-3(-) mutants. CCZ-1 forms a heterodimeric complex with SAND-1(MON1), which does not function in gut granule formation, to activate RAB-7 in trafficking pathways to conventional lysosomes. Therefore, our data suggest a model whereby the function of a Rab GEF can be altered by subunit exchange. glo-3(-) mutants, which retain low levels of GLO-3 activity, generate gut granules that lack GLO-1 and improperly accumulate RAB-7 in a SAND-1 dependent process. We show that GLO-1 and GLO-3 restrict the distribution of RAB-7 to conventional endolysosomes, providing insights into the segregation of pathways leading to conventional lysosomes and LROs.

Caenorhabditis elegans HOPS and CCZ-1 mediate trafficking to lysosome-related organelles independently of RAB-7 and SAND-1

As early endosomes mature, the SAND-1/CCZ-1 complex acts as a guanine nucleotide exchange factor (GEF) for RAB-7 to promote the activity of its effector, HOPS, which facilitates late endosome-lysosome fusion and the consumption of AP-3-containing vesicles. We show that CCZ-1 and the HOPS complex are essential for the biogenesis of gut granules, cell type-specific, lysosome-related organelles (LROs) that coexist with conventional lysosomes in Caenorhabditis elegans intestinal cells. The HOPS subunit VPS-18 promotes the trafficking of gut granule proteins away from lysosomes and functions downstream of or in parallel to the AP-3 adaptor. CCZ-1 also acts independently of AP-3, and ccz-1 mutants mistraffic gut granule proteins. Our results indicate that SAND-1 does not participate in the formation of gut granules. In the absence of RAB-7 activity, gut granules are generated; however, their size and protein composition are subtly altered. These observations suggest that CCZ-1 acts in partnership with a protein other than SAND-1 as a GEF for an alternate Rab to promote gut granule biogenesis. Point mutations in GLO-1, a Rab32/38-related protein, predicted to increase spontaneous guanine nucleotide exchange, specifically suppress the loss of gut granules by ccz-1 and glo-3 mutants. GLO-3 is known to be required for gut granule formation and has homology to SAND-1/Mon1-related proteins, suggesting that CCZ-1 functions with GLO-3 upstream of the GLO-1 Rab, possibly as a GLO-1 GEF. These results support LRO formation occurring via processes similar to conventional lysosome biogenesis, albeit with key molecular differences.

C. elegans BLOC-1 functions in trafficking to lysosome-related gut granules

The human disease Hermansky-Pudlak syndrome results from defective biogenesis of lysosome-related organelles (LROs) and can be caused by mutations in subunits of the BLOC-1 complex. Here we show that C. elegans glo-2 and snpn-1, despite relatively low levels of amino acid identity, encode Pallidin and Snapin BLOC-1 subunit homologues, respectively. BLOC-1 subunit interactions involving Pallidin and Snapin were conserved for GLO-2 and SNPN-1. Mutations in glo-2 and snpn-1,or RNAi targeting 5 other BLOC-1 subunit homologues in a genetic background sensitized for glo-2 function, led to defects in the biogenesis of lysosome-related gut granules. These results indicate that the BLOC-1 complex is conserved in C. elegans. To address the function of C. elegans BLOC-1, we assessed the intracellular sorting of CDF-2::GFP, LMP-1, and PGP-2 to gut granules. We validated their utility by analyzing their mislocalization in intestinal cells lacking the function of AP-3, which participates in an evolutionarily conserved sorting pathway to LROs. BLOC-1(−) intestinal cells missorted gut granule cargo to the plasma membrane and conventional lysosomes and did not have obviously altered function or morphology of organelles composing the conventional lysosome protein sorting pathway. Double mutant analysis and comparison of AP-3(−) and BLOC-1(−) phenotypes revealed that BLOC-1 has some functions independent of the AP-3 adaptor complex in trafficking to gut granules. We discuss similarities and differences of BLOC-1 activity in the biogenesis of gut granules as compared to mammalian melanosomes, where BLOC-1 has been most extensively studied for its role in sorting to LROs. Our work opens up the opportunity to address the function of this poorly understood complex in cell and organismal physiology using the genetic approaches available in C. elegans.

Randomized controlled trial of an Internet-delivered family cognitive-behavioral therapy intervention for children and adolescents with chronic pain

Cognitive-behavioral therapy (CBT) interventions show promise for decreasing chronic pain in youth. However, the availability of CBT is limited by many factors including distance to major treatment centers and expense. This study evaluates a more accessible treatment approach for chronic pediatric pain using an Internet-delivered family CBT intervention. Participants included 48 children, aged 11-17 years, with chronic headache, abdominal, or musculoskeletal pain and associated functional disability, and their parents. Children were randomly assigned to a wait-list control group or an Internet treatment group. Primary treatment outcomes were pain intensity ratings (0-10 NRS) and activity limitations on the Child Activity Limitations Interview, both completed via an online daily diary. In addition to their medical care, the Internet treatment group completed 8 weeks of online modules including relaxation training, cognitive strategies, parent operant techniques, communication strategies, and sleep and activity interventions. Youth randomized to the wait-list control group continued with the current medical care only. Findings demonstrated significantly greater reduction in activity limitations and pain intensity at post-treatment for the Internet treatment group and these effects were maintained at the three-month follow-up. Rate of clinically significant improvement in pain was also greater for the Internet treatment group than for the wait-list control group. There were no significant group differences in parental protectiveness or child depressive symptoms post-treatment. Internet treatment was rated as acceptable by all children and parents. Findings support the efficacy and acceptability of Internet delivery of family CBT for reducing pain and improving function among children and adolescents with chronic pain.