Respiratory Diseases

Influenza-like illness

Outpatient influenza-like illness increased this week from 3.2% to 3.4% visits to the doctor for fever and cough or sore throat. To give you a sense of where we might be headed, previous years have seen peaks between 4.9% and 7.4%, often around the turn of the new year. Emergency department visits for influenza like illness are increasing as well, now constituting around 1% of visits. Peak season can hit double digits.

Young children caught a tiny bit of a break this week with outpatient ILI falling to 10.1%, down from 10.4% the week prior for the 0 to 4 age group. The 5 to 24 year old age group also saw a slight decline to 5%. The older age groups are much lower at 3% and under.

States in the Southern region of the country continue to experience highest levels of ILI activity, particularly Louisiana and the District of Columbia, still coming in at high and very high respectively. However, several indicators point to the West as an emerging hotspot, with California and Arizona both reporting moderate levels of outpatient activity and rapidly increasing ED visits. Most of the rest of the country is reporting moderate to minimal levels of activity.

Interestingly, wastewater concentration of influenza A does not seem to be especially correlated with outpatient activity right now. Louisiana, for example, is reporting moderate levels of wastewater concentration, while outpatient ILI suggests much higher levels of activity. Similarly, New Jersey is reporting minimal levels of wastewater concentration and high levels of outpatient activity. To me, this means there's still a lot to be learned about how best to use wastewater surveillance. For now, I appreciate it as a secondary indicator.

COVID-19

Things are still quiet, but they are picking up. Wastewater activity is generally low but increasing in most places, with the highest activity in the Midwest.

If you are looking ahead to e.g., Christmas or New Year’s activities later in the month, we may be in a riskier spot. Given that we have been in a prolonged quiet period, it would not surprise me if this is the start of a sustained uptick in cases. Now would be moment to pick up some more at-home tests if your stock has run low.

Severe illness remains minimal, with the rate of trips to the emergency department still at 0.6%, and hospitalizations declined slightly to the very low rate of 1.4 hospitalizations per 100,000 people.

RSV & Other Bugs

RSV: RSV activity is still rising in parts of the country. The South leads with the highest burden, reporting ED visit rates frequently above 1% and widespread very high wastewater levels. The Northeast follows with moderate to high activity, while the Midwest shows increasing but lower levels. The West currently reports the lowest activity, though wastewater surveillance suggests rising transmission in some areas. Hospitalization rates follow similar regional trends, highest in the South (3.4 per 100,000) and progressively lower moving north and west across the country.

Other bugs: Several viral causes of respiratory infections are circulating. These all tend to cause mild to moderate upper-respiratory tract infections, with standard cold and flu-like symptoms: runny nose, headaches, cough, sore throat, and fever. However, infants, older adults, and people with weakened immune symptoms are at greater risk of developing more severe disease, including bronchitis and pneumonia.

• Human coronaviruses continue to be on the upswing.
• Rhinoviruses/enteroviruses are declining, but remain elevated (22.5% test positivity).
• Adenoviruses remain moderately elevated but appear to be declining. In addition to the standard symptoms listed above, adenoviruses can also cause a range of other symptoms, including pink eye, diarrhea, vomiting, nausea and stomach pain.
• Parainfluenza seems to have peaked and is declining. In addition to the standard symptoms listed above, parainfluenza viruses can also cause ear pain, and are a common cause of croup in small children. In more severe cases, people may develop a barking cough and wheezing.

Stomach Bugs

I’m sorry to report that norovirus is having a banner year, if test positivity is to be believed. It is up to 18.4% test positivity; this is the highest it has been at any point in the past seven years. Rates are highest in the West (21.0%) and Midwest, followed by the South and Northeast (11.7%).

Food recalls

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

New:

• Connie’s Thin Crust Cheese Frozen Pizzas (more info)
• Daily Veggies Enoki Mushrooms (more info)
• Sprouts Markers Market Gyro Family Kit (more info)
• MadeGood Granola Bars (various flavors and varieties) (more info)

Previously reported:

• A large-scale cucumber recall is affecting both whole cucumbers and prepared foods with cucumbers
• Blue Ridge Beef log Puppy Mix [for Dogs]. While not for human consumption, humans may be infected by Salmonella if they do not adequately wash their hands or contaminated surfaces after handling the product. (more info)
• Kirkland Signature Organic Eggs (more info)
• If you have food allergies, you may wish to review these FDA safety alerts and USDA alerts for foods with undeclared allergens.

In other news

• Test results are still pending for an undiagnosed outbreak in the Democratic Republic of Congo, which has now affected hundreds of individuals. A preliminary investigation of 12 cases revealed that 10 were positive for malaria. However, further testing is required to identify any additional causes contributing to the outbreak, and those results have not yet been returned.
• The CDC reports that 74 passengers (3.85%) and 4 crew members (0.5%) aboard Holland America Line's Zuiderdam cruise ship, sailing from December 4–14, 2024, experienced gastrointestinal illness caused by norovirus. In response, the ship increased cleaning and disinfection, collected stool specimens for testing, and isolated ill individuals.

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