Asymptomatic COVID-19 may not spread as easily as symptomatic

Symptomatic COVID-19 cases are responsible for more viral transmission than asymptomatic infections, suggests an updated systematic review and meta-analysis of 130 studies published yesterday in PLOS Medicine.

A team led by University of Bern researchers in Switzerland searched databases through Jul 6, 2021, for studies on COVID-19 patients with documented symptom status at the start and end of follow-up, as well as mathematical modeling studies. The studies included data on 28,426 COVID-19 patients from 42 countries, 11,923 (42%) of whom were asymptomatic.

Because heterogeneity among the studies was high, the team didn't estimate the average proportion of asymptomatic cases overall or in 84 screening studies of defined populations.

In 46 contact-tracing or outbreak studies, the total share of asymptomatic COVID-19 cases was 19% (95% confidence interval [CI], 15% to 25%; prediction interval [PI], 2% to 70%). Relative to symptomatic infections, the rate of viral spread from asymptomatic index patients to contacts was about two-thirds lower (risk ratio, 0.32; 95% CI, 0.16 to 0.64; PI, 0.11 to 0.95; 8 studies). Thirteen modeling studies fit to data revealed that the proportion of all viral transmission from presymptomatic patients was higher than that of those who were asymptomatic.

"When SARS-CoV-2 community transmission levels are high, physical distancing measures and mask-wearing need to be sustained to prevent transmission from close contact with people with asymptomatic and presymptomatic infection," the researchers wrote.

But they cautioned that the study was limited by high heterogeneity and high risks of selection and information bias in studies not designed to quantify persistently asymptomatic cases, as well as limited data about SARS-CoV-2 variants in vaccinated participants.

"The true proportion of asymptomatic SARS-CoV-2 infection is still not known, and it would be misleading to rely on a single number because the 130 studies that we reviewed were so different," senior author Nicola Low, MD, of the University of Bern, said in a PLOS Medicine news release. "People with truly asymptomatic infection are, however, less infectious than those with symptomatic infection."
May 26 PLOS Med study and news release

Salmonella outbreak tied to peanut butter grows as more foods recalled

The US Centers for Disease Control and Prevention (CDC) yesterday reported 2 more Salmonella Senftenberg cases in an outbreak linked to peanut butter, raising the national total to 16 people from 12 states.

The latest illness onset is May 2, and, of people with available information, two have been hospitalized. No deaths have been reported. The CDC said the true number of people infected is likely much higher, given that most people recover without needing care and because of the delay in confirming that illnesses are part of an outbreak.

Interviews with sick patients revealed that most had eaten Jif brand peanut butter, and on May 20, J.M. Smucker, which makes Jif, recalled Jif types of peanut butter. Also, 13 companies have recalled their products such as candy and prepackaged snack trays that contain servings of the recalled Jif peanut butter.
May 26 CDC outbreak update
May 20 FDA Jif peanut butter recall announcement
FDA list of related recalls

Pakistan reports 3 more wild polio cases

In its latest weekly update, the Global Polio Eradication Initiative (GPEI) said Pakistan reported its third wild poliovirus type 1 (WPV1) case of the year, in a patient from Khyber Pakhtunkhwa, which was followed by news today from Pakistani media of two more WPV1 cases.

The two cases confirmed today by the Pakistan National Polio Lab include two children in the same family, a girl who had a May 10 paralysis onset and a boy who had a May 11 paralysis onset, according to Pakistan Today. The report said the country has six WPV1 cases this year.

Pakistan and Afghanistan are the two countries where WPV1 is still endemic, and the uptick in cases this year is a discouraging development, as it followed a steep downturn in cases over the past few years.

In other polio developments, four countries reported more circulating vaccine-derived poliovirus type 2 (cVDPV2) cases, GPEI said in its update. Chad reported two cases, one in Batha department and the other in N'Djamena, the nation's capital, raising its total to three this year. The Democratic Republic of the Congo (DRC) reported 10 more cases, mostly in Maniema province, raising its total for 2022 to 47.

Elsewhere, Niger reported one more case, which involves a patient from Tillaberi and brings its total for the year to two. And Yemen reported 12 more cases in nine locations, boosting its 2022 total to 17.
May 26 GPEI update
May 27 Pakistan Today story

USDA announces $400 million more for avian flu response

For the third time, US Department of Agriculture (USDA) Secretary Tom Vilsack has approved funding to help the agency and its state and local partners quickly identify and manage ongoing highly pathogenic avian flu outbreaks in poultry.

In an announcement today, the USDA said it approved the transfer of $400 million from the Commodity Credit Corporation (CCC) to fund the outbreak response. The move follows a $130 million transfer in March and a $263 million transfer in late April. The CCC was established in the 1930s to stabilize, support, and protect farm income and prices.

Since the transfer in late April, there have been 151 more detections in poultry, including flocks in nine newly affected states, which led to the loss of 10.8 commercial and backyard birds.
May 27 USDA announcement

In other outbreak developments, the USDA's Animal and Plant Health Inspection Service (APHIS) reported one more outbreak in poultry, which involved a backyard flock in King County, Washington, near Seattle.

Also, APHIS reported 105 more detections in wild birds, bringing the total to 1,295. Most of the detections were in Wisconsin, Minnesota, and North Dakota, but several were from western states such as Alaska, Utah, Wyoming, Idaho, and Montana. There was one in the East, in New York. Most new detections were in raptors found dead. There were a few in other types of birds, including gulls, crows, and waterfowl.
USDA APHIS poultry avian flu page
USDA APHIS wild bird avian flu page

UK reports more unexplained hepatitis cases in kids

The United Kingdom today reported 25 more unexplained hepatitis case in kids, raising its total to 222, according to an update from the Health Security Agency (HSA), and the World Health Organization (WHO) says it is tracking 650 probable cases.

So far, most of the cases are in kids younger than 5, but the HSA said a small number of children who are older than 10 are part of the investigation.

Renu Bindra, MD, senior medical advisor and incident director, said in a statement, "Our investigations continue to suggest an association with adenovirus, and we are exploring this link, along with other possible contributing factors including prior infections such as COVID-19."

In April, the country was the first to sound the alarm about unexplained hepatitis cases in children. Since then, more than 600 cases, 14 of them fatal, have been reported by more than 30 countries.
May 27 UK HSA update

In an update today, the WHO says 33 countries in five WHO regions have reported 650 probable cases total, with an additional 99 cases pending classification.

Of the 650 cases, 374 (58%) have been in the WHO European Region, with the Americas reporting 240 cases (37%), far outpacing the Western Pacific (34 cases), Southeast Asia (14), and the Eastern Mediterranean (5). The WHO reported the same number of UK cases as did the HSA (222), adding that the United States has had 216.
May 27 WHO update

USDA food institute funds 9 projects to combat antibiotic resistance

Yesterday the US Department of Agriculture's National Institute of Food and Agriculture (USDA NIFA) announced an investment of more than $5 million, spread across nine projects, to mitigate antimicrobial resistance (AMR) across the food chain.

The $5,117,165 investment is part of NIFA's Agriculture and Food Research Initiative's Mitigating Antimicrobial Resistance across the Food Chain grant program, which supports integrated research, education, and extension projects, NIFA said in a news release. Research approaches include risk assessment, antibiotic management and stewardship, advancing understanding of emerging resistant pathogens and their mechanisms for resistance, and disease control using antimicrobial alternatives.

Funded projects include University of Florida scientists studying the effects of spraying fruit trees with antibiotics to prevent or treat citrus greening disease, Iowa State researchers modeling the movement of bacteria through different environments such as surface water, and Ohio State investigators studying the movement of auctioned calves through the market to better understand how antimicrobial drugs are used to prevent and treat disease.

"Pathogen resistance to antimicrobials is a complex problem, encompassing human medicine, poultry and livestock health, and even plant crop production," said Acting NIFA Director Dr. Dionne Toombs, PhD. "The projects supported through this investment will work to ensure a safe, nutritious and abundant food supply while conserving antimicrobial effectiveness."

NIFA says the nine projects will help strengthen the USDA's overall efforts to protect public health through agricultural research that addresses AMR. 
May 26 USDA NIFA news release

Study suggests links between resistant E coli in chickens and people

A study conducted on farms in the Mekong Delta of Vietnam suggests antimicrobial resistance (AMR) in Escherichia coli from chickens and in-contact humans is driven by antimicrobial use and potential cross-species transmission, researchers reported in JAC-Antimicrobial Resistance.

For the study, a team of researchers from Vietnam and the United Kingdom collected data on antimicrobial use (AMU) and fecal swabs from humans and chickens on 237 small-scale farms in the Mekong Delta. The researchers isolated E coli strains from 426 human and 237 chicken samples, tested their susceptibility to 11 antimicrobials, and investigated the associated between AMU on the farms and AMR levels. They also examined the degree of similarity in AMR patterns between human and chicken E coli isolates from the same farms compared with isolates from different farms.

Bases on structured One Health questionnaires filled out by the participants, the researchers estimated that 13.8% had used antimicrobials over the past 90 days, and that antimicrobials had been administered to 114 of 237 chicken flocks (48.1%). Overall, the AMU rate in chickens (299.1 per 1,000 chicken-days) was 19 times higher than the AMU rate in humans (15.1 per 1,000 person-days). Among the tested isolates, 311 (80.8%) from humans and 195 (82.3%) from chickens were resistant to at least one antibiotic. Chicken isolates displayed a higher prevalence of multidrug resistance (63.3%) compared with human isolates (55.1%).

Using logistic regression modeling, the researchers found that AMU significantly increased the probability of resistance in E coli isolates from humans (odds ratios [ORs] of 2.1 to 5.3) and chickens (ORs from 1.9 to 4.8). E coli from humans and chickens living on same farms had a higher degree of similarity in their AMR patterns than isolates from humans and chickens living on different farms. Notably, there was a suggestion of a higher probability of the co-existence of colistin-resistant E coliin humans and chickens if they lived on the same farm.

"In conclusion, using a One Health survey design that involved co-sampling of humans and chickens from same farms and integrated AMU and AMR data, we were able to demonstrate correlation between AMU and AMR, as well as potential interspecies transmission of certain resistance phenotypes," the authors concluded.
May 27 JAC-Antimicrob Resist study

Project aims to help limited-resource countries address AMR

Originally published by CIDRAP News May 25

UK-based charitable foundation Wellcome is funding and co-developing a new project aimed at helping countries with limited resources make the best use of antimicrobial resistance (AMR) surveillance data to optimize antibiotic use and help reduce the spread of drug-resistant pathogens.

Working in collaboration with the World Health Organization (WHO), an international team of researchers, data-modelers, and policymakers will study relevant existing datasets on clinical management, antibiotic resistance, antibiotic management, and clinical outcomes to develop simple systems that aim to provide low- and middle-income countries (LMICs) with a more comprehensive view of their patterns of antibiotic use.

The hope is that national governments and local policymakers can then use this information to develop locally relevant policies, guidelines, and targets to reduce inappropriate antibiotic use.

Wellcome will fund the ADILA (Antimicrobial Resistance, Prescribing, and Consumption Data to Inform Country Antibiotic Guidance and Local Action) project for 3.5 years.

"The availability of the tools that will emerge from ADILA will be another step towards enabling and empowering decision makers in countries with limited resources to design and implement local policies better adapted to their own local settings," Wellcome science and research manager Chibuzor Uchea, PhD, said in a post on LinkedIn. "This work will allow for the creation and use of more meaningful guidelines and targets and support greater national ownership of and commitment to tackling AMR."
May 24 LinkedIn post

Risk factors for death from multidrug-resistant infections identified

Originally published by CIDRAP News May 25

A retrospective study of patients at Veterans Affairs (VA) hospitals with carbapenem-resistant Acinetobacter baumannii (CRAB) and Pseudomonas aeruginosa (CRPA) infections found that positive blood cultures and more comorbidities were associated with higher odds of mortality, researchers reported yesterday in BMC Infectious Diseases.

In the study, researchers analyzed CRAB and CRPA isolates from patients treated at 142 VA facilities from 2013 through 2018 and used multivariable cluster adjusted regression models to identify factors associated with hospital length of stay (LOS) and 90- and 365-day mortality after positive CRAB and CRPA cultures.

Over the study period, they identified CRAB and CRPA in 1,048 and 8,204 patients, respectively. The number of CRAB and CRPA cultures decline by 20% and 41%, respectively.

Among patients with CRAB, 30.3% died within 90 days, and 46.5% died within 365 days, and the median LOS post-culture was 20 days. Among CRPA patients, 24.5% died within 90 days, and 40.3% died within 365 days, with a median post-culture LOS of 16 days. In the multivariable analysis, positive blood cultures were associated with an increased odds of 90-day mortality compared to urine cultures in patients with CRAB (OR, 6.98; 95% confidence interval [CI], 3.55 to 13.73) and CRPA (OR, 2.82; 95% CI, 2.04 to 3.90).

In patients with CRAB and CRPA blood cultures, higher Charlson Comorbidity Index score was associated with increased odds of 90-day mortality. In CRAB and CRPA, among patients from inpatient care settings, blood cultures were associated with a decreased LOS compared to urine cultures.

The study authors conclude that despite the observed decline in CRAB and CRPA infections in VA patients, the two multidrug-resistant organisms should continue to be considered a serious threat, and that it's important for clinicians to recognize these risk factors in infected patients and appropriately treat them in a timely manner.
May 24 BMC Infect Dis study 

WHO lays out priorities in battle against antimicrobial resistance

Originally published by CIDRAP News May 23

WHO last week published its strategic priorities for tackling AMR.

The document lays out four strategic priority areas that incorporate what the WHO says are the essential components of the AMR response at global, regional, and country levels. It also lists the key achievements and the next steps that need to be taken in those four areas.

The first priority area is strengthening and developing a common vision for the global structures responsible for coordinating a multisectoral AMR response. These include groups such as the Tripartite Joint Secretariat on AMR and the Global Leaders Group on AMR, which were established to lead the global AMR response.

The WHO says one of the next steps for these groups is to establish a panel to define and support evidence-based policies against AMR across the One Health spectrum, which includes human health, animal health, food systems, and the environment.

Priority area number two is addressing the public health impact of AMR in every country by supporting continued development and implementation of National AMR Action Plans (NAPs), which to date have been established in 148 countries but have been implemented and funded in far fewer. Among the next steps to be taken is development of tools to review and assess NAP implementation and funding in countries.

For strategic priority area three—better access to quality AMR prevention and care—the WHO says a key next step will be operationalizing the SECURE initiative, a program developed by the WHO and the Global Antibiotic Research & Development Partnership to expand access to essential antibiotics.

Strategic priority area number four is strengthening surveillance systems and mechanisms for collecting, reporting, and disseminating AMR data. To build on one of the key achievements to date in this area—the creation of the Global Antimicrobial Resistance and Use Surveillance System—the document calls for establishing a WHO AMR dashboard to monitor the global AMR response and developing and implementing national AMR surveys.
May 18 WHO strategic priorities on AMR

G7 Health Ministers commit to addressing antimicrobial resistance

Originally published by CIDRAP News May 23

The G7 Health Ministers late last week highlighted the "silent pandemic" of AMR as one of their primary health priorities.

In a communique issued after their May 19-20 meeting in Berlin, the health ministers of the G7 countries (Canada, France, Germany, Italy, Japan, the United Kingdom, and the United States) called AMR an "urgent public health and socio-economic problem" that will affect the entire globe but have a significant impact on low- and middle-income countries. Acknowledging AMR as a shared responsibility, they committed to "taking further urgent and tangible action" to address the issue.

Among the actions they committed to are establishing new and/or improving existing national integrated surveillance systems on AMR and antibiotic use in the human, animal, plant production, and environmental sectors; promoting prudent and appropriate use of antimicrobials and encouraging antimicrobial stewardship; strengthening implementation of Infection Prevention and Control Programs across the One Health spectrum; and strengthening the research and development pipeline for new antibiotics.

The communique also addressed the economic challenges that have stymied the development of new antibiotics and the need for G7 countries to develop incentives to bolster investment in the antibiotic pipeline.

"We acknowledge that it is essential to ensure a sustainable market for existing as well as new antibiotics," the group wrote. "This includes appropriate steps to address antibiotic market failure and to ensure the commercialisation and provision of existing and new antibiotics for unmet public health needs while taking into account stewardship and equitable access."

They added, "Recognising country-specific circumstances and member state competences, we will explore a range of market incentive options, with a particular emphasis on supporting relevant pull incentives." 

The other priorities addressed in the communique and included in the G7 Health Track included working together to overcome the COVID-19 pandemic, strengthening capacities to respond to new pandemics, and addressing the health risks of climate change.
May 20 G7 communique