This week in outbreaks: March 6 edition

Flu season hangs on by a thread

Force of Infection is growing! I saw a big influx of new readers last week after my recent post on moving beyond the pandemic origins debate. If you’re just joining, welcome! Each Monday, I send out a weather report of respiratory and stomach bug activity in the U.S., as well as food recalls. I gave early warning of the tripledemic (September!) and alerted readers to a surge in norovirus before it was in the news. Around once a month, I post an essay, analysis, or deep dive on an infectious disease topic. For example, I’ve reflected on missing pieces of the monkeypox (mpox) response, and whether the COVID-19 pandemic is over. If you would like to support Force of Infection, consider becoming a paid subscriber.

Respiratory Diseases

Influenza-like illness (ILI) activity remained flat this week (again! still!), with 2.6% of outpatient visits to medical providers for ILI. This is quite an unusual pattern, and I’m very curious to see how it will play out in the coming weeks.

Influenza-like illness activity for week ending February 5, 2023. Source.

Young children remain the hardest hit, with 8.2% of outpatient visits for ILI, followed by 4.0% in the 5-24 age group. My young children are still picking up little respiratory infections, to my frustration. ILI activity remained flat in older age groups, with around 1-2% of visits for ILI in adults.

There are five jurisdictions in the red zone this week, up from four last week. California joins New Mexico, Puerto Rico, District of Columbia, and New York in the high category. Most of those jurisdictions have been stuck in high for many weeks now, in what I’m sure is a prolonged frustration for parents, healthcare providers, and others who directly experience the impacts of flu season.

Influenza-like illness activity by state. Source.

On the bright side, the number of new influenza hospitalizations nationwide has fallen substantially to around 1,500, down from a high of around 26,000. Also, there are still no signs of a second influenza B wave, which sometimes crops up in the springtime.

Covid-19 activity continues to drift downward. The average number of new daily cases is around 32,000, down from a recent high of around 70,000 during the holiday season. Hospitalizations are down to around 26,000, from a recent high of 48,000. The average number of daily deaths has been fluctuating due to uneven reporting, but it’s well over 300. While we’ve come a long way since last winter when the omicron wave peaked in January at 800,000 reported cases (an underestimate) and 160,000 hospitalizations, the virus remains widespread.

I’ve been watching the seasonal coronaviruses for a few months now. Seasonal coronaviruses cause cold-like symptoms. An interesting trend has emerged at the regional level. Activity has begun to rise again in the midwestern and southern regions after dipping earlier this month. The western region has been high and remains high (unfortunately). Only the northeastern region shows sustained progress in declining activity.

A resurgence in seasonal coronavirus activity, Southern region. Source.

I continue to suspect that adenovirus activity is rising, but we don’t have great surveillance data for adenoviruses in the U.S. There are dozens of subtypes of adenovirus, and the symptoms they cause depend on the type. Respiratory infections, pink eye, and gastrointestinal symptoms can all be caused by adenovirus infections.

RSV activity is down, but its cousin metapneumovirus is picking up, according to data from CDC and Biofire. Metapneumovirus circulates in the late winter and spring. Like RSV, it causes upper and lower respiratory tract infections. Young children and older adults are at highest risk of severe illness. Options for preventive measures are the same as for COVID-19: wash your hands, avoid crowded indoor areas, and wear a high-quality mask. Also stay home when you are sick to protect others.

Stomach bugs

Norovirus activity is likely still high in the United States. Activity is high the UK as well—the UK Health Security Agency has this to say about norovirus activity:

Latest national UK Health Security Agency surveillance data shows that laboratory reports of norovirus are more than double the 5-season average prior to the coronavirus (COVID-19) pandemic. Reporting has increased across all age groups, most notably in those aged 65 years and over.

For new readers, more on preventing norovirus: The biggest concern with norovirus is preventing dehydration. This is especially important in children and older adults, who dehydrate quickly. I keep Pedialyte powder packets in the pantry, because they take up less space and have a longer shelf life than bottles of liquid rehydration products. Water, broth, popsicles, diluted juice, sports drinks, etc. are also good options. Don’t fall behind by waiting until dehydration sets in. Encourage frequent sips from the onset of illness.

Norovirus spreads very easily between people through the “fecal-oral” route. To stop it from spreading, wash your hands thoroughly after using the bathroom and before eating or preparing food. I also use hand sanitizer while I’m in public like after I use self-checkout at the grocery store or when I use public transportation, but you should know that hand sanitizer is not as effective against norovirus as hand washing. Be sure to wash your hands properly when you get home. Most importantly, stay home if you have vomiting or diarrhea. 

If someone in your household gets norovirus, you can reduce the chance it will spread by keeping them out of the kitchen and disinfecting contaminated (read: bathroom) and shared surfaces. Also regard laundry like bedsheets, clothes, and towels as contaminated. Use gloves when handling the items and wash them thoroughly with hot water on the longest cleaning cycle.

Welcome, March! In the DC area, unseasonable warmth has brought out the cherry blossoms. Photo by Masaaki Komori on Unsplash

Food recalls:

The following foods are being recalled because they are contaminated with bacteria that causes food poisoning. Please check your cupboards and throw out any of these items:

New this week:

• None

Reported in the last month:

• The Ezricare/Delsam eye product recall has been expanded to include Artificial Eye Ointment due to contamination with a pathogen that could cause blindness. The original recall applied to Artificial Lubricant Eye Drops. (more info, more info).

• Various Signature Select Breakfast Bowls, including products containing sausage, egg, potatoes, and more. These items were sold in Nevada and California (more info).

• Ready-to-eat sausage and charcuterie products sold by Daniele International, LLC (more info).

• There is also a multi-state outbreak of Listeria linked to deli meats and cheeses, but the specific source has not been identified. If you are pregnant, over the age of 65, or have a condition that weakens your immune system, consider avoiding meat or cheese from deli counters. (more info)

• If you have food allergies, you may wish to review these FDA safety alerts for foods with undeclared allergens.

In other news

• According to the UK Health Security Agency, the number of reported invasive group A strep infections (iGAS) has slowed down somewhat, but remains above usual levels. iGAS is a severe bacterial infection that requires prompt identification and treatment, as it can lead to life-threatening complications. The surge in iGAS cases this year is thought to be linked to the high levels of viral activity (i.e. the tripledemic). Viral co-infection is a risk factor for developing iGAS.

• I am still keeping a close eye on avian influenza A(H5N1), also known as bird flu. H5N1 is widespread in birds, and spillover cases in mammals are regularly reported. While the virus is primarily an animal health concern, public health officials are watching closely for signs of human to human transmission. This is a theoretical possibility, but one worth monitoring and preparing for. Recently, Peru announced that nearly 3,5000 sea lions were found dead of H5N1, a huge increase over the 585 deaths previously reported.