The pathophysiological basis of hemorrhage in dengue infections remains poorly understood, despite the increasing global importance of these infections. A large prospective study of 167 Vietnamese children with dengue shock syndrome documented only minor prolongations of prothrombin and partial thromboplastin times but moderate to severe depression of plasma fibrinogen concentrations. A detailed study of 48 children revealed low plasma concentrations of the anticoagulant proteins C, S, and antithrombin III, which decreased with increasing severity of shock, probably because of capillary leakage. Concurrent increases in the levels of thrombomodulin, tissue factor, and plasminogen activator inhibitor type 1 (PAI-1) indicated increased production of these proteins. Thrombomodulin levels suggestive of endothelial activation correlated with increasing shock severity, whereas PAI-1 levels correlated with bleeding severity. Dengue virus can directly activate plasminogen in vitro. Rather than causing true disseminated intravascular coagulation, dengue infection may activate fibrinolysis primarily, degrading fibrinogen directly and prompting secondary activation of procoagulant homeostatic mechanisms.

Background Little is known about the natural history of asymptomatic SARS-CoV-2 infection or its contribution to infection transmission. Methods We conducted a prospective study at a quarantine center for COVID-19 in Ho Chi Minh City, Vietnam. We enrolled quarantined people with RT-PCR-confirmed SARS-CoV-2 infection, collecting clinical data, travel and contact history, and saliva at enrolment and daily nasopharyngeal throat swabs (NTS) for RT-PCR testing. We compared the natural history and transmission potential of asymptomatic and symptomatic individuals. Results Between March 10th and April 4th, 2020, 14,000 quarantined people were tested for SARS-CoV-2; 49 were positive. Of these, 30 participated in the study: 13(43%) never had symptoms and 17(57%) were symptomatic. 17(57%) participants acquired their infection outside Vietnam. Compared with symptomatic individuals, asymptomatic people were less likely to have detectable SARS-CoV-2 in NTS samples collected at enrolment (8/13 (62%) vs. 17/17 (100%) P=0.02). SARS-CoV-2 RNA was detected in 20/27 (74%) available saliva; 7/11 (64%) in the asymptomatic and 13/16 (81%) in the symptomatic group (P=0.56). Analysis of the probability of RT-PCR positivity showed asymptomatic participants had faster viral clearance than symptomatic participants (P<0.001 for difference over first 19 days). This difference was most pronounced during the first week of follow-up. Two of the asymptomatic individuals appeared to transmit the infection to up to four contacts. Conclusions Asymptomatic SARS-CoV-2 infection is common and can be detected by analysis of saliva or NTS. NTS viral loads fall faster in asymptomatic individuals, but they appear able to transmit the virus to others.

Doreen Tembo and colleagues argue that small changes as well as larger system-wide changes can strengthen citizens’ contribution to knowledge in health research

Objective. To evaluate a concise program of selfcare education delivered by an arthritis nurse specialist as an adjunct to primary care for inner-city patients with knee osteoarthritis (OA).Methods. An attention-controlled clinical trial; 211 inner-city patients with knee OA were assigned arbitrarily to education (E) or attention-control (AC) conditions. Group E received an individualized 30-60-minute educational intervention that emphasized nonpharmacologic management of joint pain, preservation of function by problem-solving, and practice of principles of joint protection. Brief telephone contacts 1 week and 4 weeks later monitored and reinforced new selfcare activities. Group AC viewed a 20-minute standardized public education presentation on arthritis and received followup telephone calls (only to encourage continued participation in the study). Outcomes included the Health Assessment Questionnaire (HAQ) Disability and Discomfort Scales, 10-cm visual analog scales measuring knee pain at rest and while walking, and the Quality of Well-Being (QWB) scale. Assessments were made at baseline and at 4-month intervals for 1 year.Results. A total of 165 subjects (78%) completed all assessments. After control for baseline status, group E had significantly lower scores for disability and resting knee pain throughout the year of postintervention followup (P C 0.05 for both). Effects were somewhat discordant. By 12 months, functional benefits had begun to wane, while the effect on resting knee pain had grown. The overall effects of education on walking knee pain,