Respiratory Diseases

Influenza-like illness

‘March comes in like a lion, out like a lamb’ is proving true for flu season. Outpatient visits for influenza-like illness (that is, fever and cough or sore throat) decreased to 3.3%. I expect we will have exited flu season by next week, dropping below the 3.1% baseline that marks the end of the season, as measured by activity.

All age groups are reporting decreases in visits to the doctor for ILI. Rates for those aged 0-4 have decreased to 9.6%, down from this season’s peak of nearly 20%. Outpatient ILI for those aged 5-24 has decreased to 6.5%, and the 25-49 age group has decreased to 2.7%. Rates for older age groups have decreased to below 1.8%.

Severe illness is also declining. ED visits are down to 1.9% at the national level. At the regional level, activity as measured by ED visits ranges from ~1.8% in the Northeast to ~2.2% in the Midwest. Contrast this with late December, when ED visits were at a miserable 8.6%.

Flu B continues to account for a large proportion of late-season cases — 76.5% of samples in clinical labs, and 47.2% in public health labs.

COVID-19

Covid-19 activity remains quiet in most of the country. Just 0.4% of all ED visits are due to Covid-19, and wastewater activity is low and declining nationally.

The CDC’s Center for Forecasting and Outbreak Analytics estimates that Covid-19 is declining or likely declining in nearly every state. The exceptions are Washington, Pennsylvania, and Washington, DC, where activity is stable. (In Georgia, New York, and Hawaii, there was not adequate data to make estimates.)

In the South, Northeast, and Midwest, ED visits are ~0.5% and decreasing. Wastewater activity in the Midwest has finally decreased to low levels; it is the lowest it has been since November. Wastewater activity is also low and declining in the South and is very low and declining in the Northeast. The West is in the best shape.

Severe illness continues to slowly decline as well, with hospitalizations decreasing to 0.9 per 100,000 people.

RSV & Other Bugs

RSV: Activity remains quite high but has peaked in most of the country.

Indicators are starting to show improvements. For instance, test positivity has decreased slightly, to 8.3%. ED visits remain elevated at 0.5% for the total population, but decreased for the youngest (and most heavily affected) age groups. The proportion of visits to the ED that are for RSV declined to 4.5% for infants, and to 3.8% for those 1-4 years old.

Hospitalizations held roughly steady at 2.5 hospitalizations per 100,000 people for the total population. However, this is an improvement compared to mid-February, when hospitalizations were up to 43.9 per 100,000 for infants; that has declined to a still-high 26.6.

Other bugs: Several causes of colds continue to circulate widely.

• Human coronaviruses peaked and dropped several points this past week; however, they remain quite high.
• Human metapneumovirus continues its upward climb. Activity is starting to near last season’s peak.
• Adenovirus activity is picking up from moderate to higher activity.
• Parainfluenza activity is very low; rhinoviruses/enteroviruses are low.

Norovirus

Norovirus is still very active. Despite a slight dip this past week, norovirus is still on a week-over-week increasing trajectory: test positivity was a high 14.9% this past week.

Activity held roughly steady at very high levels in the Midwest (17.6%). It increased further in the West, to 13.1%.

In the South and Northeast, activity remains high but dipped slightly (to 14.1% and 11.8%, respectively). I would hesitate to take a single week as evidence of a decreasing trend though. Noro data tends to be quite jagged.

Food recalls

The following foods are being recalled because they are contaminated. Please check your cupboards and throw out any of these items:

New:

• Nothing new this week (however - see In Other News)

Previously Reported:

• Expanded recall of frozen chicken fried rice products, sold under multiple brand names: Trader Joe’s, Ajinomoto, Kroger, Ling Ling, and Tai Pei, due to possible glass shards (more info)
• Great Value (sold at Walmart) Cottage Cheese (more info)
• Elite Treats Chicken Chips (for dogs). These may be contaminated with salmonella, which poses a health risk not only for dogs, but also for humans who handle the product or contaminated surfaces (more info).
• Bremer Family Size Italian Meatballs (frozen, ready-to-eat) (more info)
• Multiple flavors of cream cheese under the Made Fresh Salads, Inc. label (more info)
• Gerber Arrowroot biscuits (more info)
• Organic chia seeds sold by Navitas Organics (more info)

In other news

• Unpasteurized cheddar cheese linked to E. coli outbreak. Unpasteurized (‘raw’) cheddar cheese sold by Raw Farm LLC is being investigated by the CDC, FDA and health officials in California, Florida, and Texas in an outbreak of Shiga toxin-producing E. coli. There have been 7 cases (4 in children 3 years of age or younger) and 2 hospitalizations identified to date. All affected individuals who were interviewed reported consuming this brand before becoming ill, and genetic analysis of samples from affected individuals were closely linked, suggesting a common source of infection. The CDC is recommending that consumers “consider not eating any affected cheese” while the investigation is ongoing. The company has refused to issue a voluntary recall.

• Meningitis outbreak in the UK. There have been 20 confirmed cases and 2 deaths in a meningitis B outbreak in Kent, England, linked to a nightclub exposure. (This number might be a bit lower than others you have seen because some suspected cases have, on further testing, been ruled out.) Meningitis B is caused by the bacteria Neisseria meningitidis; it can cause severe illness and death. Public health authorities have given out more than 12,000 doses of preventive antibiotic to those at high risk in Kent, and a campaign to vaccinate thousands of young adults has reached over 8,000 so far.

  • Meningococcal disease spreads through close contact with respiratory secretions, for instance during kissing or sharing food and drinks, or living in the same household. Symptoms appear and progress rapidly, moving from fever, headache, and muscle aches to stiff neck, severe headache, sensitivity to light, and difficulty staying awake. A rash or very cold hands and feet may also be present. It is critical to seek medical care as soon as possible if meningococcal disease is suspected.

• Measles continues to spread widely in the US. The confirmed case count rose to 1,487 last week across 32 jurisdictions. The rate of new cases is slowing in the large South Carolina outbreak; however, hotspots in Utah (275), Texas (147), and Florida (122) are picking up.

• Summer schedule. This is the last free edition of the flu season. Free coverage will resume in October, when flu season begins again. Paid subscribers will continue to receive a weekly report through the summer months.