I've had an ear worm all week after I heard the Grateful Dead's Ripple play on the radio. Little did I know it was a spooky foreshadowing for my weekend.
Meanwhile, measles is dominating the infectious diseases news, with only a few notable exceptions.
New Dengue Alert
CDC issued a new alert about dengue risk in the US. Not only are Puerto Rico and U.S. Virgin Islands hot spots for dengue acquisition, we continue to have significant spillover into the continental US, including in persons who haven't traveled to endemic areas. These autochthonous infections arise when enough of the local mosquito population becomes infected from travelers returning from endemic regions. Here's the map of total US dengue cases for 2025 so far:
Drilling down on the same website to look at just the autochthonous (locally acquired) cases:
Clearly just a handful of autochthonous cases, but spring has just started and summer is ahead, a good time for a reminder to practice good mosquito bite prevention measures. In 2024 we had a little over 10,000 dengue cases in the US, about 6500 of which were autochthonous, led by Puerto Rico. Florida, California, and Texas were the higher-risk states for locally acquired dengue in 2024.
For people having trouble choosing among various mosquito repellants, scroll down to the Insect Repellent Bot on that same prevention page for an interactive discussion.
Cholera
WHO has raised the alarm about global cholera outbreaks. Cholera is tough to track, so the case counts probably represent significant undercounting. So far in 2025 WHO has tallied 70,488 cases and 808 deaths from cholera and acute watery diarrhea.
We have both effective vaccines and treatments, but still a very tough problem to control.
Measles Marches On
We are in for a long year of measles. The Texas/New Mexico/Oklahoma (I think I'll call it TeNMO) outbreak isn't slowing down, and control measures are hindered by likely underreporting with infected individuals not seeking medical attention. I was hoping the rural nature of the epicenter in Texas would limit spread, but travel and low vaccination rates are conspiring against us. Going forward I will focus mainly on CDC numbers as a whole, unless unique aspects about local infections warrant discussion. Remember that Texas and New Mexico are reporting case counts and other information regularly.
Here are current CDC data:
Measles Deep Dive #2
Last week I probably confused everyone about the measles reproductive number in Deep Dive #1. This week's dive addresses the measles risks for children under 12 months of age, before routine measles vaccination is recommended.
An offshoot of the Texas outbreak was an exposure of newborns in a hospital in Lubbock, Texas, to a mother admitted in labor who was found to have active measles. If the mothers of exposed infants had immunity through vaccination or natural infection, these other newborns likely are protected though I'm sure they underwent evaluation and immunoglobulin treatment. I've never seen a case of neonatal measles, probably because I've always practiced in an area where the vast majority of women of childbearing age have immunity. I was interested in an oldie-but-goodie article from Japan describing 7 children < 30 days of age who acquired measles from their mothers. Three developed pneumonia but thankfully all did well. The interesting part of the report was that the rash was atypical in 6 infants, appearing on the same day as the fever started (i.e. no 2-4 days of cough, coryza, conjunctivitis prodrome) and before the fever in 2. All had Koplik spots.
Travel season is upon us, and recommendations for vaccination for children as young as 6 months who plan international travel hasn't changed.
"Persons aged 6 months and older who will be traveling internationally to any country outside the United States who do not have presumptive evidence of immunity should be vaccinated with measles-containing vaccine if they are not already protected against measles, mumps, and rubella. Before any international travel—
- Infants 6 through 11 months of age should receive 1 dose of MMR vaccine. Infants who get one dose of MMR vaccine before their first birthday should get 2 more doses according to the routinely recommended schedule.
- The first dose should be given at 12 through 15 months of age and the second dose at 4 through 6 years of age.
- The second dose can be administered earlier as long as at least 28 days have elapsed since the first dose.
- The first dose should be given at 12 through 15 months of age and the second dose at 4 through 6 years of age.
- People 12 months of age and older who will be traveling internationally should receive 2 doses of measles-containing vaccine;A unless they have other presumptive evidence of immunity against measles. The second dose should be administered no earlier than 28 days after the first dose."
Local health departments may recommend this early vaccine dose for infants 6-11 months of age who are deemed to be at risk from individual outbreaks as well, certainly pertinent to some areas of Texas and New Mexico at least.
As most primary care providers know, this early measles dose doesn't count as part of the routine 2-dose MMR vaccination; the early dose is sometimes called "dose 0" so that it won't be counted. Response to measles vaccine at 6 months of age isn't robust and can be inhibited further if maternal antibody is still present in the infant. However, data from around the world suggest that virtually no 6-month-olds will have detectable measles antibody. Here's a study from Belgium as an example:
This seems to be the case in resource-poor communities as well.
WRIS
I'm hoping this will be my last regular posting for this year's winter respiratory infection season. National levels of respiratory illness are low, as are most states.
Influenza-like illness continues to fall, though still above baseline. We still have some "red states."
I won't have a WRIS update until/unless something changes.
New Water Wonderland
Mid-week I had a plumber in the house to fix a problem with my shower water temperature and, while he was at it, fix a minor drainage problem in the basement. By Saturday I had a new wading pool in my basement, complete with ripples when I run water from anywhere in the house. I'm a very unhappy camper and hoping this gets fixed soon. The joys of home-owning.