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Tag: COVID-19

Published on Leave a comment on Settling Into Winter

I'd been spared from most snow shoveling due to mild winters the past few years. Fortunately, this week I discovered that my outdated acetaminophen still seems to work.

Artificial Intelligence for Pediatric Infectious Disease Diagnosis

Investigators at Baylor College of Medicine (bias alert: my alma mater) developed an interesting method to distinguish the covid-associated Multisystem Inflammatory Syndrome in Children (MIS-C) from endemic typhus, the latter enjoying a bit of a resurgence in south Texas. The rest of us don't have reason very often to consider these 2 entities together since endemic typhus (aka murine or flea-borne typhus) is pretty rare in the US beyond southern California, southern Texas, and Hawaii. However, the results from this preliminary study serve as a proof-of-concept model for other diseases. The methodology is very complex, to say the least. Briefly, they looked at electronic medical record data over a 2-year period for anyone being tested for Rickettsia typhi, the etiologic agent for endemic typhus, or having a rheumatology consult request for MIS-C. All of the typhus-positive patients and a subset of MIS-C patients were included in a preliminary dataset for the AI modeling. A large number of patient variables were tested in an iterative process to come up with a preliminary scoring system which was then validated on another MIS-C patient set. The final scoring system included 15 variables: age of patient, duration of fever, height of fever, highest heart rate, neutrophil to lymphocyte ratio, AST, ALT, sodium, troponin, BNP, fibrinogen, epidemiologic link to COVID-19 case, antecedent illness, conjunctivitis, and rash. The authors claimed their scoring system correctly classified all 220 patients in their training dataset (100% accuracy) and was 99% accurate in the 160-patient MIS-C cohort used as the validation dataset. Of course we still need further evidence that this works well in other settings and institutions. I hope the AI and machine learning process itself, so far published only as a preprint, can be applied to other clinical situations.

Another Tick-borne Virus

Speaking of vector-borne infections, now researchers in China report a novel virus from the Nairoviridae family was found to be a cause of febrile illness in 26 of 252 febrile patients tested in northeastern China. They named it XCV (Xue-Cheng Virus) after the geographic site. (IMHO, I wish we could get away from naming diseases according to a geographic site, it just encourages xenophobia.) They also found evidence that XCV caused cytopathic effect in vitro and was present in 3-6% of ticks in the area. They authors don't provide much clinical information about the cases, and a link to a supplementary appendix didn't contain any more details. Overall it does appear this is a new infectious pathogen.

If you never heard of nairoviruses, don't feel bad. Some infectious diseases physicians may be aware that Crimean-Congo hemorrhagic fever virus is the main human pathogen in this family.

Chronic Wasting Disease

I don't think I've ever mentioned CWD in these pages previously. It is a fatal neurodegenerative disease seen in cervids (deer, elk, moose, reindeer) and caused by an infectious prion. I've been watching reports about spread of CWD in the US and across the globe for many years. I mention it now because of the publication of a new report from CIDRAP concerning for potential for spillover into other species, including humans, similar to what has happened in humans with Creutzfeld-Jakob Disease, kuru, and bovine spongiform encephalopathy (mad cow disease). Here's the North American distribution of CWD.

CWD has been expanding in numbers and in geographic areas in the US the past 20 years, increasing the possibility of spillover into humans. The CWD prion can remain intact in the environment for years, and prions are not inactivated by cooking infected meat.

The report maps out several recommendations for monitoring this situation; the recommendations bullet list alone takes up 5 pages of the 102-page document. It's a good example of how to plan proactively, but of course implementation takes funding of public health endeavors.

Venison steak, anyone?

Good News in the Vaccine Department

Three quick comments on recent vaccine studies.

First, I was somewhat surprised to see a pretty good uptake of RSV prevention modalities for pregnant people and infants. In the 2023-24 RSV season in the Kaiser Permanente Northern California system, around 75% of at risk infants received protection either by maternal vaccination or nirsevimab administration after birth.

I'm hoping it is even better this season. Remember that Kaiser is a health system very well designed to deliver high rates of vaccinations and other preventive interventions to its subscribers. However, individual private medical practices can and should aim to achieve high rates of RSV prevention.

Another study provided more evidence that it is safe to administer 2-month vaccinations to hospitalized preterm infants. It was a randomized controlled trial of preterm (<33 weeks gestation) infants hospitalized at 3 NICUs and eligible for vaccination at 6 - 12 weeks of age. 223 babies were randomized to receive either 2-month vaccines or no vaccine and then monitored for 48 hours. The unvaccinated group of course could receive vaccines after this 2-day period. Although apnea was more common in the vaccinated group, it didn't appear to have any adverse effects.

The vaccines administered were PCV13, DTaP, HBV, IPV, and Hib.

The last vaccine study I'll mention is another estimate of flu vaccine effectiveness last year. Specifically, it looked at outpatients at least 8 months of age in 7 states that were part of a flu VE surveillance system. The target endpoint was outpatient visits with positive influenza testing. VE against any influenza illness was 41% (95% Confidence Interval [CI]: 32 to 49): 28% (95% CI: 13 to 40) against influenza A(H1N1)pdm09, 68% (95% CI: 59 to 76) against B/Victoria, and 30% (95% CI: 9 to 47) against A(H3N2). Protection was found in all age groups except for the 50-64-year-old group. Differences in age groups (and also related to influenza A subtypes) likely are related to imprinting, i.e. what flu strains people are exposed to early in life, but this study wasn't designed to answer this question.

WRIS

As we roll along in the winter respiratory infection season it's worth taking a look at where we are. CDC has some newer data for the "big 3" viruses in pictorial form. (See https://www.cdc.gov/flu-burden/php/data-vis/2024-2025.html, https://www.cdc.gov/rsv/php/surveillance/burden-estimates.html?ACSTrackingID=USCDC_2067-DM142871&ACSTrackingLabel=CDC%20Updates%20%7C%20New%20In-Season%20Estimates%20of%20COVID-19%20and%20RSV%20-%201%2F7%2F2024&deliveryName=USCDC_2067-DM142871, and https://www.cdc.gov/covid/php/surveillance/burden-estimates.html?ACSTrackingID=USCDC_2067-DM142871&ACSTrackingLabel=CDC%20Updates%20%7C%20New%20In-Season%20Estimates%20of%20COVID-19%20and%20RSV%20-%201%2F7%2F2024&deliveryName=USCDC_2067-DM142871.)

Note that the influenza numbers include 2 weeks longer than for RSV and covid. I did a quick calculation of death rates per illnesses for each, using the midpoint of the ranges: influenza 1.3 deaths/1000 illnesses, RSV 2.5, and covid 3.1. Of course these are all ballpark estimations but still show that infections with any of the big 3 are worth preventing.

Here's the most recent look from FluView, which captures respiratory illnesses other than influenza.

Still hoping that flu and RSV reach their peaks before covid ramps up.

Español en la Nieve

My shoveling activities were greatly enhanced by one of my new neighbors, a 3-year-old boy who just moved here from Colombia and only speaks Spanish. I'm forever embarrassed by the fact that the Spanish I've retained from my south Texas childhood can't be used in polite company, but my new friend was speaking his native tongue to me while we shoveled together. The upside if we have a heavy snow winter in Maryland is that I may develop new Spanish fluency!

Published on Leave a comment on Bye Bye Birdie?

Regular readers may recall my new infatuation with bird watching triggered by the gift of a video bird feeder from a daughter-in-law. In this era of avian influenza evolution, one might legitimately ask whether a septuagenarian should gown, glove, and mask when performing weekly seed replacement and monthly cleanings. The short answer is no; the birds at most bird feeders in the US are not displaying high rates of infection. I just won't be touching any dead fowl or starting a backyard chicken coop anytime soon.

Here's what I ran across this past week.

Managing the Febrile Infant

This is one of those conundrums that has plagued me since medical school in the late 1970s. It's not that we haven't made progress (GBS prophylaxis, for example), but we still lack reliable methods to distinguish which febrile newborns need empiric antibiotic therapy and which can be safely observed without antibiotics. The latest iteration in the discussion looked at prospectively-collected data from 2018-2023 on well-appearing febrile infants 8 - 60 days of age at a single center in Canada. The investigators were particularly interested in predictive data without using serum procalcitonin measurement. AAP Practice Guidelines recommend using PCT but also provide guidance for assessment if PCT measurements are not available in a timely manner.

From the sample of slightly less than 2000 infants the Canadian investigators developed a new decision rule, with some internal validation, to manage low-risk infants. The new rule maintained high sensitivity (and therefore high negative predictive value) while improving specificity from 51% to 84%, resulting in fewer infants receiving unnecessary therapy. The rule incorporated CRP, maximum temperature, and ANC. (IBI denotes Invasive Bacterial Infection.)

It's important to note, as the authors do, that this was a single center study. In general, it's wise to wait for validation from other sites (this was an urban tertiary care center) more similar to your own practice setting before implementing a new practice. Also, only 38 infants had IBI, not surprising since most fevers in infants are due to viral infections, but the low numbers of IBI cases might result in lower validity. This study, and any resultant guidelines, apply to a relatively healthy group; to qualify for the study, subjects had to be well-appearing, previously healthy infants of at least 37 weeks gestation. A number of standard exclusion criteria such as no prior antibiotics and no focal infections, underlying medical disorders, or other high risk factors for infection also were employed. This approach certainly could be an improvement to current guidelines, but 84% specificity is far from what I would want for ideal management of a frequent clinical problem.

Which IGRA Test is Better?

Testing for tuberculosis infection is at the top of diagnostic dilemmas that have plagued me for my entire career in medicine. Interferon gamma release assays are a big improvement over tuberculin skin testing primarily because they remove the error problems of application and interpretation of the skin test and are not affected by prior BCG vaccine administration. Aside from those circumstances, IGRAs have about the same sensitivity and specificity as skin testing.

A new study looked at discrepancies between the 2 main IGRA tests, Quantiferon and T-spot, in a multi-center US pediatric population. Subjects for this study were less than 15 years of age and had risk factors for TB infection, but were not thought to have active TB disease; in short, these were children being screened for latent tuberculosis infection. The rate of indeterminate test results was similar between the 2 tests, about 0.3%. However, the rate of positive tests was higher for Quantiferon than for T-spot.

Particularly interesting was that the reasons for the higher positivity of Quantiferon wasn't evident. It did not vary with the child's age (note too few positives in the children younger than 2 years of age to be confident of those results), whether the tests were borderline positive, i.e. close to the cutoff for positivity, or reason for performing the TB screening test.

This report doesn't tell us which test is better in this setting. We can't determine false positive or false negative rates from the data, a problem with every study of latent TB infection because the subjects would need to be followed for years without receiving preventive treatment, clearly unethical. We still have a lot to learn about TB.

Norovirus in the News

I've seen a lot lately, and not just the usual cruise ship headlines. Due to how norovirus outbreaks are reported, it's hard to know if what we are seeing now is something highly different from pre-pandemic years, but let me remind everyone that norovirus is a winter disease.

Also, remember that alcohol-based hand sanitizer won't work for norovirus; use real soap and water for an extended scrub. Norovirus vaccines of various types are under development, including a recently-launched phase 3 trial in adults in the UK.

Are My Red M&Ms on the Way Out?

I'm really not branching out from infectious diseases commentary and won't pretend to be an expert on cancer-causing chemicals, but we've all seen the concerns about red dye #3 in foods in recent news reports. Maybe this is a bow to the new political administration and possible public health leadership. Regardless, from afar I'm confused about why a compound that is associated with cancer in laboratory animals, and is essentially a food cosmetic is still on the market.

Believe it or not, there is a pediatric infection connection with red food colorings. I first heard about this 1965-66 pediatric Salmonella outbreak at the Massachusetts General Hospital from a pediatric resident present at the time who later became one of my mentors. Summarizing a lot of data and leaving out my mentor's colorful anecdotes which may be embellished, the source of the outbreak was a red dye used for measuring intestinal transit time - give the dye capsule and watch for red-colored stools. The key component was carmine, derived from a cochineal insect Dactylopius coccus that produces the red pigment carminic acid. These insects are found primarily in Mexico and Central America, and processing at the time was found to be ineffective at killing Salmonella.

The food industry seems dependent on food colorings, but I'd prefer less additives that serve only to colorize my food.

WRIS

Some of my CDC tracking sites are still a bit behind due to the holidays, but we are certainly in full-blown Winter Respiratory Virus Season. The Influenza-Like Illness map is leaning towards the red end of the visible light spectrum (note CDC seems to have moved blue outside of its normal position in the spectrum!).

The drivers are primarily influneza A and RSV. Covid is low but rising, and covid wastewater monitoring suggests we'll see a significant uptick in the coming weeks.

Avian Influenza

This is still a low probability for concern but should be closely watched. This past week saw a more complete report of the case of severe avian flu in a Canadian teenager that reminded me how poorly news reports and press releases characterize specific cases. I had initially thought, based on news reports, that the severe disease might be due to secondary bacterial complications, but in fact this was just bad, high viral load, avian influenza. We now know that the child was an obese (BMI was "greater than 35") 13-year-old-girl, previously healthy except for mild asthma, who required intubation and ventilation, then ultimately ECMO, for survival. She first became ill on November 2, was seen in an emergency department with conjunctivitis and fever on November 4 and sent home, then admitted in respiratory distress on November 7 and transferred to an intensive care unit on November 8. She had multiple complications including renal failure requiring hemodialysis. She was off all oxygen therapy by December 18.

One additional concern in the report was the presence of a mutation in the hemagglutinin gene that might facilitate better adaptation to the human respiratory tract, similar to the Louisiana adult with severe avian flu infection. We need to keep a close watch in general on avian flu mutations in wildlife but also in humans, particularly those who have severe disease with high viral loads that facilitate mutations that increase human adaptation. Still, there is no evidence of human-to-human transmission which is the most reassuring finding at present.

I've been trying to monitor how the federal government is prioritizing avian flu. Last summer the USDA introduced a program to compensate poultry farmers for monetary loss due to avian flu infecting their flocks, and a proposed update was announced recently. I know that researchers at CDC, NIH and elsewhere are working hard on variant assessments and development of stockpiles of effective vaccines and alternative antiviral agents.

Our 39th President

I'd be very remiss if I didn't stop to comment on President Carter's passing. He certainly had an up-and-down stint during his 1 term as president, but his subsequent work in public health was phenomenal. Take a moment to review the public health accomplishments via the Carter Center. I hope our current and future leaders will take a page from his playbook as we deal with upcoming public health challenges.

Guinea worm disease is a major impediment to a farmer's ability to work. Dressed in his farming clothes, Nuru Ziblim, a Guinea worm health volunteer in Ghana, educates children on how to use pipe filters when they go to the fields with their families. Pipe filters, individual filtration devices worn around the neck, work similarly to a straw, allowing people to filter their water to avoid contracting Guinea worm disease while away from home. In May 2010, with Carter Center support, Ghana reported its last case of Guinea worm disease and announced it had stopped disease transmission a year later.

Location: Ghana | Date: February 2008 | Photo: The Carter Center/L. Gubb

Published on Leave a comment on The Year in Review

It's fashionable for this time of year to give some reflections on the events of the last 12 months; seemingly every pundit/publication does it in some form or another. I won't buck the trend. What follows is a bit of a "highlight reel," plus the 3 things I'm watching closely for next year.

The Unexplained Explained

Recently we all had the opportunity to watch as a mystery outbreak unfolded in the Democratic Republic of Congo. Was it a novel pathogen set to launch a new pandemic or simply a localized outbreak of a known pathogen, complicated by poor health resources delaying accurate diagnosis and treatment? It took a little longer than I predicted to unravel everything, but we now have an answer from WHO as of December 27. That's still pretty quick, the original alert from the Panzi health zone in the Kwango province was November 29. I'm reassured that our global public health system is working well for outbreak detection.

The case definition used for investigation was fairly broad: "any person living in the Panzi health zone from September 2024 to date, presenting with fever, cough, body weakness, runny nose, with or without one of the following symptoms and signs: chills, headache, difficulty breathing, malnutrition, body aches." Here's an excerpt from the report:

"As of 16 December, laboratory results from a total of 430 samples indicated positive results for malaria, common respiratory viruses (Influenza A (H1N1, pdm09), rhinoviruses, SARS-COV-2, Human coronaviruses, parainfluenza viruses, and Human Adenovirus). While further laboratory tests are ongoing, together these findings suggest that a combination of common and seasonal viral respiratory infections and falciparum malaria, compounded by acute malnutrition led to an increase in severe infections and deaths, disproportionally affecting children under five years of age."

In other words, it was a combination of known pathogens already present in the area, layered on a background of falciparum malaria and malnutrition: a perfect storm. Let's hope the added health resources will dampen the outbreak in this very rural, isolated region of the DRC. Nutritional support is particularly needed.

WHO 2024

The WHO published its look back at 2024, including "highlights, breakthroughs and challenges." Many countries achieved milestones in either elimination or significant decreases of a number of diseases, including human African trypanosomiasis, leprosy, lymphatic filariasis, trachoma, malaria, measles, and mother-to-child transmission of HIV, syphilis, and hepatitis B. Their Expanded Programme on Immunization celebrated its 50th anniversary this year, with an estimated 154 million deaths prevented, most of them infants.

WRIS

CDC took a bit of a holiday break this week, so the level of detail in reports is less. However, Winter Respiratory Infection Season is officially High nationally.

The big 3 (covid, influenza, and RSV) all are increasing at this point. I'm hoping they don't peak at the same time and cause big logjams in healthcare settings.

What I'm Watching For

Mpox

In spite of the few cases in North America, Asia, and Europe, mpox is still primarily an African problem. As we know, however, no communicable disease in one area is just a problem limited to that area - international spread is always a few contacts away. In that regard, I found a recent review/opinion article enlightening.

Of interest, smallpox (vaccinia virus) vaccine protects against mpox infection. Our success in eliminating smallpox and subsequent cessation of smallpox vaccination led to a new population susceptible to mpox infection. A major hurdle to control the outbreaks will be vaccinia virus vaccine testing and distribution to high risk populations.

Avian Influenza

The influenza A H5N1 viruses now circulating in birds (both domestic poultry and wild birds) and dairy cows is the most likely source of a new pandemic, but fortunately the risk is still very remote especially if the public health system can keep on top of tracking infections and characterizing variants.

In the past week we learned that feeding your cat raw pet food derived from poultry is not a good idea, it resulted in 1 cat death in Oregon. I think most of us could have predicted that. One thing for cat owners to keep in mind is that the current avian flu, while still causing some respiratory symptoms in felines, is noteworthy for neurologic symptoms.

Also this week we learned about the mutation found in the hemagluttinin gene segment in the Louisiana human patient with severe avian flu illness. This is the H1 part of the virus which is important for attachment to respiratory epithelial cells. Mutations in this area can increase the effectiveness of spread in humans. However, it is completely expected that a human infected with the virus and experiencing severe disease would develop these types of viral mutations. What would be more concerning is if an isolate from a bird or cow developed such mutations, because of the potential for wider spread.

The risk for widespread human A H5N1 infections is still extremely low. I'll be watching in 2025 for any evidence of human-to-human transmission as well as any significant changes in the virus circulating in the wild animal kingdom. Again, I'm reassured that surveillance is allowing for rapid sequencing of human isolates. I hope that resources continue to be available to track this virus in animal and human populations.

SARS-CoV-2

Covid remains a wild card. It has perhaps the highest mutation rate of any virus causing human disease, it has yet to develop a true seasonality like other coronaviruses making it difficult to plan vaccination recommendations, and infections are still relatively frequent plus underreported due to lack of resources for testing, public apathy, and misinformation/disinformation fueling political decision-making. In short, we're in big trouble if another new variant appears with significantly greater pathogenicity and infectivity.

WHO published another year in review on covid that included a big overview of what's happened since 2020. They do note that our tracking systems worldwide are diminished compared to earlier in the pandemic, so recent data are likely to be significant underestimates. In the post-pandemic phase, we all need to transition from the type of extensive pandemic case tracking into a more sustainable surveillance system similar to what we do for influenza.

I was surprised to see some areas blank for what's going on the US, perhaps due to delayed reporting, and I was also a bit overwhelmed trying to decide what graphs to display here; if you're interested I'd suggest perusing the document itself. First, I've copied a quick highlight summary:

  • While there are periodic waves of COVID-19 in some countries, SARS-CoV-2, the virus that causes COVID-19,
    largely circulates without clear seasonality and continues to infect, cause severe acute disease and post
    COVID-19 condition.
  • The impact of COVID-19 has varied by country depending on the circulating variants, national policies,
    capacities to respond and access to countermeasures.
  • WHO’s ability to monitor circulation, severity, virus evolution and impact is challenged by reduced
    surveillance, testing, sequencing, limited integration into longer term infectious disease prevention and
    control programs, and reporting, as Member States adapt from crisis management to longer term prevention
    and control of COVID-19.
  • Changes to COVID-19 surveillance over the past five years have been consistent and expected, adapting to
    the changing landscape of the pandemic. Many Member States are transitioning from comprehensive case
    reporting to integrating SARS-CoV-2 monitoring into existing respiratory disease and infectious diseases
    surveillance systems. This is an important step towards sustainable infectious disease surveillance,
    monitoring and risk assessment. At the present time, the integration of SARS-CoV-2 into existing influenza
    surveillance systems is variable across regionsranging from 41% in countries from the Western Pacific Region
    to 96% in countries in the European Region.

Here's a great overview of the past few years on a global level.

Even with more inaccuracies in tracking recently, it's nice to see how far we've come in lowering cases and deaths.

Here's a look at deaths by age group, but what isn't apparent in the graph is that mortality rates in infants are comparable to mortality in 20-45-year-olds. Another advertisement for vaccination of pregnant people, who themselves are in high risk group.

And here's the crazy lack of seasonality expressed as percentage of positive tests. I might be tempted to see a trend towards winter seasonality, but remember these data include the southern hemisphere and thus we should see a biphasic pattern if/when seasonality develops.

And lastly a look at how far our variants have drifted over time.

Auld Lang Syne

My apologies to Scotsman Robert Burns, but I must turn to Londoner (with Scottish heritage) Sir Rod Stewart for my favorite version of the song at Stirling Castle in Scotland, complete with bagpipes.

Wishing everyone a Safe and Happy New Year. See you next year.

Published on Leave a comment on The Wiedermann Thanksgiving Massacree of 199?

Thanksgiving week has arrived, which for me means making checklists and time schedules and then revising them several times up until Thursday, at which point nothing happens according to schedule and I just go with the flow. It's also a time I remember the infamous Wiedermann Thanksgiving Massacree of 199? (I can't remember the exact year), with apologies to Arlo Guthrie.

Understandably in the past few years, this blog has drifted to the latest public health and epidemiologic trends, but I'm comforted by the fact that respiratory infections remain relatively calm and that this past week's publications allow me to focus more on recent original studies of interest to pediatric healthcare providers and the general public.

Macrolide-resistant Mycoplasma pneumoniae

I'm getting pretty tired of hearing about our resurgence of "walking pneumonia," but this article caught my eye. It's a report from North Dakota, and my interest wasn't in the fact that the investigators found evidence of macrolide resistance; that's nothing new. The bigger question is whether the resistance has major clinical significance. I've stated previously that, because Mycoplasma lower respiratory infection is largely a self-limited disease, it's difficult to know whether antibiotic treatment helps, and if it does, whether the amount of benefit is worth treating with antibiotics. The vast majority of "walking pneumonia" cases in children don't need any nasal swab or radiographic testing, nor any treatment.

The study was small, just based on 10 children of which 8 had macrolide resistance genes detected in their nasal swab assays. Six of them were said to have failed azithromycin treatment, though the authors didn't define treatment failure. Six of the patients who had fever and received doxycycline or levofloxacin became afebrile within 24-48 hours. Needless to say, this doesn't translate to great evidence that macrolide resistance is clinically important; it does point to the fact that we need randomized controlled trials to answer this question. Unfortunately, studies need funding, and this condition isn't likely to be profitable enough for funding from a pharmaceutical company. My only takeaway from the study is that further evaluation and treatment should be considered in children with possible pneumonia in whom symptoms worsen or fever persists more than a few days. Unfortunately, M. pneumoniae susceptibility testing isn't routinely available. For mild community-acquired pneumonia in children, amoxicillin is the treatment of choice, with azithromycin as a second-line agent. Switching to doxycycline or levofloxacin should be reserved for macrolide treatment failure, however that is defined.

Certainly we are having a banner year for mycooplasma respiratory infections, likely a combination of the normal mycoplasma surges we see every few years and lack of exposure during pandemic years. Which brings us to ...

Immune Debt

I really liked this new article that looked at the concept of a dose response effect in immune debt, i.e. that the magnitude of illness we see in rebounds of respiratory infections post-pandemic should be proportional to how much less frequent these infections were during the pandemic. The statistical methods in the study are somewhat beyond my expertise, but I mostly think the authors proved their point that lifting of non-pharmaceutical interventions (NPI) around the world seemed to be a point of increase for various respiratory infections. Here's a sample of the findings.

If this is all true, presumably we'll be back to the "old normal" of seasonal respiratory infections soon (barring another serious pandemic).

UTI Diagnosis

I must confesse my eyes rolled when I saw the title of this new study. Early in my career I was involved in UTI research. I've been very disappointed in analyses of UTI diagnosis in recent years because most of them seemed to ignore how variable accuracy of different UTI diagnostic laboratory methods are, even for something as basic as urinalysis. For example, it makes a big difference whether the number of white blood cells in urine is determined by machine (usually flow cytometry), manual counting by a lab technician with or without use of a hemocytometer, or just a urine leukocyte esterase dipstick. So, I was very pleasantly surprised that this group of investigators highlighted precisely those concerns. This was a study of around 4000 febrile children evaluated for UTI with urinalysis and culture, and the results showed that virtually all urinalysis components were poor at predicting a positive urine culture, defined as > 50,000 cfu/mL of a single pathogen in a catheterized urine specimen. The authors concluded that around 20% of children with febrile UTI could have normal urinalyses but also acknowledged how difficult it is to factor in asymptomatic bacteriuria (estimated rate 2%, but tough to assign an exact number) and specimen contamination. I don't think this study solves any of these issues, but it is an important contribution to our understanding of UTI diagnosis.

WRIS and Nowcasting

Last week CDC published a more detailed explanation of how the time-varying estimated reproductive number (Rt) can be used as an early warning for changes in respiratory pathogen transmission activity. This report is of interest mostly to true epidemiologic nerds, so of course I found it very enlightening. The authors did provide convincing evidence that this methodology has been working well recently.

We're not due for another respiratory illness outlook update from the CDC until mid-December, they only provide these every 2 months, but we remain mostly quiet. I suspect we'll see RSV and influenza hit pretty soon around the country. Again, you can check your own local illness and wastewater activity at the CDC' site.

Beware Studies Based on Administrative Data

This is one of my pet peeves: not the studies themselves, but how too much importance seems to be given to them in the lay press (bolstered by academic organizations seeking to get their names in the news). A new study shows how variable results can be from these databases, using the example of invasive bacterial infections in febrile infants. It's easy to imagine how any system based on diagnosis codes entered into various databases could lead to classification errors, but this report provides an excellent example to keep in mind. Any study using an administrative database should evaluate accuracy of diagnoses on a subset of patients to give some evaluation of the accuracy of their results (IMHO).

New 2025 Vaccination Schedules Published

The information isn't new, just based on prior FDA and ACIP deliberations mostly happening over the summer, but now we have the colorful schedules to use. The AAP has a quick summary of changes.

Happy Thanksgiving!

I have so much to be thankful for this year, and I hope not to repeat the Wiedermann Thanksgiving Massacree of maybe 30 years ago. I won't explain in full; it's too painful to spend anything like the 18 minutes, 34 seconds that Arlo Guthrie took to explain his Alice's Restaurant Thanksgiving Massacree of 1965. (Restaurant namesake Alice Brock died a few days ago.) The short version is that my attempt to create the perfect turkey gravy ended badly in an oil slick of glass shards in the kitchen. Why I'm still allowed to have any Thanksgiving responsibilities at all is a prime example of my wife's incredible powers of forgiveness.

We'll be hosting a relatively small gathering at our place this year. My duties are limited to turkey, gravy, and drinks. Starting today I'll have my checklists made out, separated into daily tasks. Thursday itself will have a well-choreographed timeline to include oven and stove use times in our smallish kitchen. As I said at the start, these scraps of paper will bear little resemblance to how the meal actually unfolds.

I won't go into detail about all the food-borne illnesses linked to turkey dinners, but please make good use of your food thermometer and follow guidelines.

And, speaking of Arlo, some of you might be interested in his live recording of "Amazing Grace" with Pete Seeger in 1993 (around the time of the Wiedermann Massacree!). It's 13 minutes of music and meanderings still meaningful in today's world.

Published on Leave a comment on Fall Back

Once again I find myself, an ostensibly tech-savvy individual,* faced with manually resetting the time on 11 clocks and appliances in my house. Only my phone, laptops, and tablet appear to have joined the 21st century by self-correcting to eastern standard time. Of course, if our country had truly joined the 21st century, we wouldn't be making this twice yearly switch in the first place.

My election anxiety is somewhat mollified by focusing on infectious diseases, so you can categorize the following as therapeutic in nature.

WRIS

Still not much going on, though I was intrigued that my state of residence is 1 of only 2 to show up with moderate respiratory illness activity last week.

I'm pretty impressed by how quiet the SARS-CoV-2 front is. However, it's still around, and we can expect to see a resurgence sometime.

The fact that influenza has not yet appeared might indicate we are returning to a more "normal" flu season. The graph below shows how different the prior 3 flu seasons were from pre-pandemic experiences, where last year had a very early peak and 2020-21 and 2021-22 had very low and atypical peaks. (Apologies for CDC's labelling here, but if you stare at it long enough you can pick out which line goes with which year.)

New Development in Bird Flu

The so-called highly pathogenic avian flu H5N1 cropping up in dairy and poultry farms and in wild bird populations has been in the news for many months now. It still seems to be a mild illness in humans, most of whom have direct exposure to these farms. Only 41 humans have confirmed infections in 2024 so far. What's a bit noteworthy this week is that the virus may now have shown up in pigs. USDA officials reported probable swine cases at a backyard farm in Oregon where poultry, cows, and pigs all mingle. The farm itself has no role in commercial production of any foods, so it isn't a risk to others. What is of slight concern is the fact that pigs are involved. Pigs have a special place in influenza science because they have both human and avian flu receptors in their respiratory tracts, making the chance for a recombination event to occur if they happen to be infected with human and avian viruses at the same time. Most of the time this doesn't cause creation of a new pandemic strain, and I wouldn't hit the panic button at all now. Actually I'm surprised it took this long for swine infection to be found. The affected animals were all euthanized and multiple studies are ongoing, so I'm sure we'll hear more about this.

Polio

The news isn't great as both wild and vaccine-variant polio cases continue to be reported. This Global Polio Eradication Initiative map is a good summary.

No new cases have been reported in Gaza, with just the 1 case confirmed so far. The interrupted vaccination campaign in northern Gaza restarted this week.

Dengue Still Going Strong

I was browsing the CDC dengue page this week; infections are still plentiful.

Puerto Rico has the greatest number by far, but note that we have had autochthonous (locally acquired without travel to endemic areas) dengue in the mainland US (California with 11 cases, Florida with 49).

*

Can I really claim to be tech-savvy? I think so. I have an advanced degree in educational technology with classes that included instruction in networks and the various hardware involved; the fact that my schooling ended in 2008 shouldn't disqualify me. Also, this past week I restored to full health our K-cup brewing machine that became confused and wouldn't deliver the appropriate coffee volumes or allow the correct menu choices in its buttons. I guess in the interest of full disclosure, when I couldn't find a satisfactory replacement brewer online, my astute intervention was reading the instruction manual, realizing that I hadn't ever de-scaled the device in the approximately 90 years I've owned it, and made it new again using only a low-tech tool (vinegar).

In spite of my skills with technology and vinegar, I'll be performing my semiannual time resets for the foreseeable future; I could never part with my grandfather's clock.

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