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Tag: COVID-19

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.

Published on Leave a comment on Information, Knowledge, and Wisdom

I regularly read Ron Charles's Washington Post Friday Book Club newsletter, always chock full of interesting topics and writers I haven't yet explored. This Friday he included a quote from controversial (accused of plagiarism) Turkish author and activist Elif Shafak

“... we are living in a world in which there is way too much information, but little knowledge and even less wisdom.… As we scroll up and down, more out of habit than out of anything else, we have no time to process what we see. No time to absorb or reflect or feel. Hyper-information gives us the illusion of knowledge. For true knowledge to be attained we need to slow down. We need cultural spaces, literary festivals, an open and honest intellectual exchange.”

This blog is my attempt to machete a trail through all the various forms of information and provide some bridge to knowledge and wisdom by providing links to reliable original sources. Speaking of which, we are now in the midst of ID Week, probably the most prestigious annual infectious diseases research conference, and many of my regular ID feeds are filled with reports of presentations. However, I virtually never include these reports in this blog, because there is no way via these abstracts to look for potential flaws or limitations in the research, and it is well known that research meeting presentation findings often change dramatically by the time they are published in a peer-reviewed journal, if they are ever published at all.

WRIS

Still pretty quiet on the Winter Respiratory Infection Season, with some hints of beginnings of influenza and RSV increasing. Perhaps the only item of interest is an increase in Mycoplasma pneumoniae activity, probably just a regular wave that tends to happen with this pathogen, though delayed somewhat due to pandemic mitigation strategies. It's not a reportable disease, so it's hard to find good data on incidence over time. As most providers know, this is a self-limited illness that produces generally mild illness (so-called walking pneumonia) and usually not worth diagnosing or treating. Because of its self-limited nature, it's been difficult to demonstrate any benefit of antibiotic treatment compared to placebo, and I doubt we'll see any placebo-controlled randomized trials in the near future.

Compared to last winter, CDC is predicting a 54% chance of a similar combined peak of respiratory illnesses, with a 28% chance of a lower peak and 18% chance of a higher peak.

Infectious Complications of Hurricanes

These tend to get less coverage than do the more obvious loss of life and property destruction occurring immediately during a natural disaster, but the Florida Department of Health is now reporting on a surge in cases of necrotizing fasciitis due to Vibrio vulnificus, a known salt and brackish water pathogen. Here are the numbers:

As a reminder, individuals with immunodeficiencies, but also particularly including chronic liver or renal disease, are at high risk for V. vulnificus complications. CDC has a good summary.

Conjunctivitis

Researchers in Colorado looked at about 200 children with acute conjunctivitis compared to a similar number of children who were either healthy or had URI without conjunctival involvement. Long story short, they found no benefit of ophthalmic ointment treatment, but did see a 20% incidence of antibiotic side effects. The study itself didn't replicate real-world situations for providers; for example, they employed broad spectrum PCR testing looking for a large number of bacteria and viruses. The study doesn't give us much direction for practical approaches to this problem but does serve as a reminder to limit topical and other antibiotic use in acute conjunctivitis in children,

Outpatient Infant Botulism?

I would never have thought of this, I've only been called for hospitalized children with infant botulism. It turns out, though, that there are rare instances of milder disease managed as outpatients. A team reviewing the California Department of Public Health data from 1976 - 2021 found 17 of 4372 cases (0.4%) were outpatients. (Note that California cases account for about 1/3 of all US infant botulism cases.) Here's the breakdown of clinical findings.

The median age at onset of symptoms was 20 weeks, with a range of 6 - 55 weeks. Only 1 child had been exposed to honey.

Polio Updates

The second round of novel oral polio type 2 vaccinations have begun in Gaza, though I haven't heard much about ceasefires to help facilitate this critical second round. Meanwhile, this week the Global Polio Elimination Initiative had to bow to reality and revise plans and timeline for polio elimination worldwide. Now, the end of 2027 is the target for elimination of wild poliovirus infections, with end of 2029 for elimination of type 2 vaccine-derived polio. This will take significantly more funding, and the greater the risk of prolonged or new wars the less likely these targets will be achieved.

The DIKW Pyramid

I'm accustomed to using the evidence-based medicine pyramid for hierarchies of study design in medicine, but in researching Dr. Shafak's quote about wisdom I happened onto the Data, Information, Knowledge, and Wisdom pyramid. It doesn't appear to incorporate anything about the role of false or misleading data, so I'm not sure if it is a helpful model in our era. As artificial intelligence becomes more entrenched (it's impossible to remove that view from Google Chrome!), we need to be even more vigilant about our data sources.

HAL 9000 looks a lot like my doorbell. Yikes!

Published on Leave a comment on Melanerpes carolinus

I just returned from a mad dash to Orlando, FL. No, I wasn't paying Mickey and Minnie a visit, just putting in an almost cameo appearance at the American Academy of Pediatrics National Conference and Exhibition. Apparently they were desperate for speakers because they invited me to give a talk about how to approach reading journal articles. A few dozen attendees politely endured my presentation, but I, and I think even most of the attendees, had a fun time. I also got to chat with a few old friends, always nice.

Although the trip was nice, I was most excited about the notice I received from my bird feeder while I was away. More on that later.

Potpourri

I came across a smattering of unrelated items this past week, grouped here.

I think we could all use some good news from the Middle East now. The WHO announced that Jordan has become the first country in the world to be certified to have eliminated autochthonous (locally-acquired) leprosy. That is no mean feat and required tremendous efforts and resources both from the country of Jordan as well as the WHO. It has been over 20 years since they've had an autochthonous case in Jordan.

The CDC has sent out a notice about mpox prevention through their Health Alert Network. It's not new, but worth reviewing to understand risk groups and to remind us to ask about international travel plans of our patients.

I've deliberately avoided commenting on the possible person-to-person spread of influenza A H5N1 in Missouri, but it's been in the lay press. Close contacts of 1 confirmed case had illnesses that could be consistent with this form of bird flu, but we don't have any test results from the contacts. I just mention it to stress that this is an evolving story. It would be a change for this organism if human-to-human transmission is now common.

Vaccine News

A couple intriguing reports last week from the CDC via the weekly MMWR. First are survey results that give us a glimpse at what happened with childhood immunization rates during the pandemic. It should surprise no one that vaccination coverage at 24 months of age declined by a few percentage points from birth year 2018-19 to birth year 2020-2021. For the combined 7-dose series (doesn't include covid vaccination) the rate dropped from 70.1% to 66.9%. This just adds to the possibility for sustained epidemics especially if clusters of poorly immunized children are grouped together. Here's a list of the national data for the 2020-2021 birth year cohort:

The entire table was too large to put in everything here, but Montana had the lowest numbers followed by California at second worst. You can look up your state and region in the article.

The same MMWR also had some new data on covid in children under 6 months of age. It provides compelling rationale for maternal immunization. First, here's what age-associated covid hospitalization rates look like from the surveillance network:

Further data showed that infant hospitalization rates are higher than rates in the elderly (75 years and above). In a subset of 1148 infant records that underwent extensive review, 9 deaths were recorded. Overall 22% of the hospitalizations involved intensive care admissions. Looking just at the 1065 infants for whom maternal vaccination status was available, it appears that maternal vaccination during pregnancy could be an important preventive measure for severe infant covid illness.

Note the careful wording: "No record of maternal vaccination during pregnancy." This points to the fact that these records might have been incomplete or even wrong - the providers may have recorded information incorrectly, or the mother may have been mistaken about vaccination status and timing. I'm still impressed with the information, especially since these numbers are very recent, from the omicron period when virtually every adult had some sort of immunity either via natural infection, vaccination, or both. Maternal covid vaccination is important to protect both the pregnant person, itself a high risk group, as well as the infant who is too young to receive covid vaccine.

A New Antiviral for RSV?

A placebo-controlled, randomized, double-blind trial of a few hundred infants hospitalized for RSV in China suggests that a newer antiviral agent, ziresovir, might be an effective treatment.

The main endpoint is change in the "Wang score" which is a relatively unvalidated scoring scale for assessing RSV severity. You can see the decline in the score is a bit better with the treatment group compared to placebo, but is the change in score clinically important? As a still wet-behind-the-ears ID attending, I witnessed early studies of randomized, double-blind, placebo-controlled trials of aerosolized ribavirin for hospitalized infants with bronchiolitis; my boss, a renowned pediatric infectious diseases physician named Bill Rodriguez, headed up these multi-center studies. I witnessed potential pitfalls in using scoring systems for bronchiolitis, particularly the problem with intra- and inter-rater reliability in assessments: it's hard to be consistent with scoring when the events you're looking at are somewhat subjective. Also, the aerosolized ribavirin left a fine powder on the infants, difficult to disguise even when the nurse tried to remove it before the investigator did the scoring. So, it wasn't perfectly double-blinded, in some cases not blinded at all. At blinding wasn't a problem with ziresovir, which is administered orally. Aerosolized ribavirin did work, but ultimately the costs outweighed the benefits (plus some risk to providers of inhaling the medication if the patient room was not well-ventilated and potential for teratogenicity), so the practice didn't last long.

I'll wait to see more data about this intriguing new agent. In the meantime, remember we have very effective methods of preventing severe RSV disease in infants by either maternal vaccination or administration of long-acting monoclonal antibody (nirsevimab) to infants whose mothers were not immunized.

Crystal Ball Time

What's coming this winter, and how bad will it be? Don't place any big bets on the CDC's latest predictions, they have only low to moderate confidence with their model, but it's by far the best data we have.

Here goes: "CDC expects the upcoming fall and winter respiratory disease season will likely have a similar or lower number of combined peak hospitalizations due to COVID-19, influenza, and RSV compared to last season."

That's good news. The experts were moderately confident of predictions for individual infections, but it's not really possible to anticipate all of the variables that could change the predictions dramatically, such as immunization uptake. Of course, if a new covid variant arises with a very effective immune escape mechanism, no one will be betting and we'll be in for a bad time.

Here's some more tidbits:

For example, if our summer covid activity peaks early (which it seems to be doing), they predict a milder winter season than if covid continues to rise now.

If you're a nerd like me, you can look at their description of how they developed this prediction model.

For the Birds

Getting back to my bird feeder, regular readers will recall my travails discussed in prior posts, including battling squirrel seed raiders. Things have settled down now, and I seldom see new species, but the past 2 days I've had my first sightings of a red-bellied woodpecker. The first thing I noted from my feeder's video (still photo taken below) is that I don't see a prominent red belly.

Other views show the typical zebra-like striping on the wings - why not call it the zebra woodpecker? - and the Cornell app quickly identified its call as the red-bellied variety. As usual, I couldn't help but see what new woodpecker tidbits I could learn from the worlds of literature and music. My childhood and adolescent "career" playing tenor saxophone made me a fan of big band music, particularly of Glenn Miller, and I discovered he had recorded The Woodpecker Song. It's not that great in my opinion, but at least I learned something new. One of my other musical heroes, Chuck Berry, recorded a purely instrumental (with saxophone solo!) song called Woodpecker. My favorite find, though, was a new-to-me poet, Elizabeth Madox Roberts. She was a Kentucky-born daughter of a Confederate soldier, active as a poet and novelist in the late nineteenth and early twentieth centuries. She seems to have the largest numbers of poetry web sites extolling her virtues for poems about woodpeckers. Here's her poem The Woodpecker in its entirety:

The woodpecker pecked out a little round hole
And made him a house in the telephone pole.

One day when I watched he poked out his head,
And he had on a hood and a collar of red.

When the streams of rain pour out of the sky,
And the sparkles of lightning go flashing by,

And the big, big wheels of thunder roll,
He can snuggle back in the telephone pole.

Published on Leave a comment on Invasive Species

Last week I outsmarted myself. The closing photo in the September 8 blog I was sure would result in at least 1 person calling me out; I was then going to follow up in this week's post to explain about invasive species. I guess I forgot to factor in the politeness of my audience in not wanting to berate me for mistakes. (This is a more preferable explanation than the alternative that no one even read that post!)

Still not much going on with our summer respiratory season. The percentage of ED visits due to covid continues to fall nationally.

However, covid wastewater levels in the western US plateaued or even increased a little.

Measles Still Here

It looks like we have settled into a persistent trickle of cases in the US. I'm still holding my breath hoping we can avoid another major outbreak this year. The official tally for 2024 now is 251 cases from 30 states and DC.

Not included in the totals above is a new case occurring in an unvaccinated student at Western Kentucky University, probably acquired during international travel. It looks like that person attended several public events over a few days in late August; with an incubation period of around 2 weeks, we should be hearing soon if secondary cases resulted from this person.

Meanwhile, the UK has reported a measles death in a "young person who was known to have other medical conditions." With 2465 confirmed measles cases so far this year, the UK is much worse off than we are in the US. Still, it's unsettling to hear about measles deaths in high income countries. The UK has had 1-5 deaths per year since 2019 but hasn't had double-digit death figures since 1988. Best estimates are that, even with the best medical care, 1-3/1000 children with measles will die.

A Couple Vaccine Updates

Nothing really new here, but it's easy to overlook important guidance with the flood of emails and other reminders we receive. First is the official statement from ACIP about Hib vaccination for American Indian and Alaskan Native infants. It is the follow up from an ACIP meeting last June. For both socioeconomic and biologic reasons, it's been clear for decades that this population has a very high rate of Hib disease and also a less robust response to most Hib vaccines compared to the general US population. The best Hib vaccine for this group is a conjugate using the Hib polysaccharide PRP joined to an outer membrane protein from Neisseria meningitidis. The OMP is a carrier protein that helps infants form antibody to PRP, the real protective antibody here. This is the basis for all conjugate vaccines; it fools the infant immune system into thinking it is seeing a protein antigen rather than a polysaccharide antigen; PRP and other polysaccharide antigens are not well recognized by infant immune systems - normal infants even fail to form antibody to PRP with natural Hib disease. Conjugate vaccines fool infant immune systems.

At any rate, for a long while we've only had 1 Hib vaccine with the PRP-OMP combo: PedvaxHIB. This summer we saw FDA approval of Vaxelis, a hexavalent vaccine with DTaP, IPV, HepB, and Hib, the latter using the PRP-OMP product. Vaxelis is now officially recommended as an option for the AI/AN infant population, as well as for other infants. The recommendation for the AI/AN group was made on the basis of a phase IV randomized study of Vaxelis versus PedvaxHIB showing good antibody formation in both groups. No effectiveness study was performed because this population didn't have enough Hib disease present at a background rate to determine any significant differences with a new vaccine - PedvaxHIB has worked very well for these children in the past, another vaccine success and cause for celebration.

A second vaccine update is just the recommendation, again from CDC, for the next round of covid vaccines recommended for everyone 6 months of age and older. Again, nothing new, but it's a good resource to have all that information in one document. The tables serve as a quick reference for many different situations.

Mosquito Invasion

Any ID physician worth their salt will obtain an extensive travel history when seeing patients. We are mostly looking for clues to diseases seen mostly in international travelers, such as typhoid fever and the vector-borne infections that include dengue, chikungunya, malaria, and others. However, sometimes the travel history is negative but the patient ends up having one of those exotic diseases, acquired locally in the US (aka autochthonous infection). Such is the case recently with autochthonous dengue fever cases in Los Angeles County, CA. These cases appear when there is an existing reservoir of infected people plus a reservoir of the vector. For dengue virus, the vector is the Aedes mosquito, specifically A. albopictus and A. aegypti, plentiful in much of California.

The range of these mosquitoes have been increasing the past few decades at least, mostly due to warming of our climate. The last extensive study of Aedes presence in the US was in 2017, summarized by CDC.

As one of those people who seem to be particularly tasty for mosquitoes, I find it interesting (and depressing) that we have about 200 different species of mosquitoes in the US. I'm not terribly comforted by the fact that only about a dozen of these can transmit those infections we worry about. Besides the Aedes genus, we also need to worry about Anopheles and Culex mosquitoes.

Of these, it is Aedes that is the most versatile in transmitting disease to humans, implicated in Cache Valley virus disease, chikungunya, dengue, eastern equine encephalitis, La Crosse encephalitis, and zika infections. Anopholes can spread Cache Valley virus, and Culex are implicated in eastern equine encephalitis, St. Louis encephalitis, and Oropouche virus, though midges more commonly spread the Oropouche. Other viruses such as Jamestown Canyon virus can be spread by many different species of mosquitoes and vary with time of year and location.

As our global temperatures have warmed, the mosquito season has lengthened; in many locations mosquitoes are out and about throughout the year. Also, the idea that high altitudes are safer from mosquito-borne infections is becoming invalid in many parts of the world, including the US. It wasn't the altitude per se that mosquitoes didn't like, it was the cool weather which now is warming.

I realize that for many of you this is already too much mosquito information, but if you want more visit Arbonet.

More Invasion

Getting back to last week's post, I had mentioned that my wife was outside working hard to clear our back yard of poison ivy while I was indoors typing leisurely. It turned out she didn't find any poison ivy. The photo I placed at the end of the post wasn't poison ivy but rather a portion of the massive porcelain-berry plant she removed instead. While poison ivy is a native plant, not invasive but still hated, porcelain-berry is a horribly invasive vine deliberately introduced into the US for its attractiveness but quickly discovered to spread indiscriminately, eliminating native vegetation in its path. It is the plant world equivalent of pod people.

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