chikungunya – Pediatric Infection Connection

After one failed retirement attempt, I'm trying again. I just entered a new phase to decrease my coverage of inpatient telemedicine services at regional hospitals and, if demand isn't increasing terribly, I'll phase out completely. In the meantime, I'm revving up for watching the Winter Respiratory Infection Season (WRIS).

WRIS

Nothing strikingly new or concerning on the covid, influenza, and RSV fronts, according to CDC. Respiratory illnesses, wastewater levels, and ED visits are pretty flat or decreasing most places. Florida is starting to show an increase in RSV; typically that region starts sooner than the rest of the country. Of course all viral activity varies geographically, and you can look at your own region with CDC's interactive program at that link.

I admit to having some personal interest in following this closely now. I'm trying to figure out timing of my flu vaccine; as a septuagenerian I may have more rapid waning of immunity after vaccination than do younger generations, plus preliminary data from the Southern Hemisphere suggests a slightly lower flu vaccine effectiveness this year. The key term here is preliminary. These estimates are based on very low sample sizes, and estimates always change once the full season can be evaluated.

Speaking of vaccines, the UK provided a more straightforward guidance for covid vaccination this year. The eligibility groups are pretty limited:

During the 2024 autumn campaign the following groups should be offered a COVID-19 vaccine:

all adults aged 65 years and over including individuals aged 64 who will have their 65th birthday before the campaign ends (31st March 2025)
residents in a care home for older adults
individuals aged 6 months and over who are in a clinical risk group, as defined in tables 3 and 4 of the Green Book chapter 14a

As I've mentioned before, the UK with its National Health Service relies heavily on cost effectiveness analyses, leading to a more restricted target population than in the US.

Two Viruses on the International Scene ...

Marburg Virus in Rwanda

Marburg activity in Rwanda is increasing, and the CDC sent out an advisory last week. Marburg virus is another of the hemorrhagic fever flaviviruses, like Ebola; it has a high fatality rate. As in other hemorrhagic fever virus outbreaks, healthcare workers are at high risk if they are not careful with exposure to blood and body fluids. Most of us remember the spread of Ebola to the US, and already there's been a scare in Hamburg, Germany, but the ill traveler returning from Rwanda tested negative. The name comes from the German city of Marburg which was one of the sites (the others were Frankfurt, Germany, and Belgrade in what is now Serbia) of laboratory outbreaks of the illness in 1967, linked to African green monkeys imported from Uganda. Let's hope efforts to contain the infection are successful, but it's a tough task in low-resource regions.

Perinatal Chikungunya

A new study from Brazil suggests a relatively high rate of transmission of this virus from pregnant people to their newborn infants. The study period covered the years 2016 - 2020. Here's the summary numbers:

Symptoms in infected infants included, in addition to rash and fever, some more severe conditions like DIC, vesiculobullous eruption, seizure and encephalitis, and respiratory failure. It was both a retrospective and prospective case series, and I learned a new term: ambispective!

... But Also Some International Success

The WHO recently declared Brazil has successfully eliminated lymphatic filariasis as a public health problem, a major milestone. The only countries successful previously with filariasis were Malawi and Togo in the WHO African region; Egypt and Yemen in the Eastern Mediterranean region; Bangladesh, Maldives, Sri Lanka, and Thailand in the South-East Asian region; and Cambodia, Cook Islands, Kiribati, Lao People's Democratic Republic, Marshall Islands, Niue, Pilau, Tonga, Vanuatu, Viet Nam, and Wallis and Futuna in the Western Pacific region. Time to dig out that world map!

Filariasis is one of 20 Neglected Tropical Diseases targeted by WHO for improved control by 2030.

Lower Vaccination Rates in US Kindergartners

CDC updated vaccine coverage rates for the 2023-2024 year and, no surprise, it's dropping. The decrease may be driven at least in part by an increase in non-medical exemptions. This news doesn't bode well for future outbreaks of vaccine-preventable diseases, but the clinical impact is largely determined by geographic distributions at the community level. The site has a lot of data, worth some browsing, but here's a quick look at MMR coverage by state for 2023-2024:

Any state that isn't the darkest blue has high risk for outbreaks. Even within the dark blue states any pockets of poor vaccine coverage, such as communities or schools that have high rates of vaccine-averse parents, could see outbreaks.

How's Your Outpatient Antibiotic Prescribing Score?

A cross-sectional database study of about half a million antibiotic subscriptions in 2022 from Tennessee showed some interesting results. The investigators looked at both appropriateness of antibiotic choice and duration of treatment; only 31% of prescriptions were appropriate for both. Here's the quick look at optimal antibiotic choice by disease:

Here's what it looked like for duration of therapy. Standard durations reflect current guidelines, whereas contemporary durations are taken from more recent studies suggesting shorter courses are effective. The number of days in parentheses are the contemporary durations.

Again, another study worthy of browsing if you commonly prescribe antibiotics for these conditions.

November 5 is Fast Approaching

Although I'm trying to wind down my practice, it seems like my to-do list is twice as long now. We're all busy, but please don't forget to vote!

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.

Tag: chikungunya

Winding Down (Again)