Infectious Disease Roundup: 2/4/2025

Respiratory virus infection remains high in the US, Tuberculosis is on the rise, 4 measles cases in Texas, and a novel virus reported in Alabama shrews- similar viruses have 70% fatality rate

Update on Respiratory Viruses, Norovirus in the US

According to wastewater data from wastewaterscan.org (below) we may be just starting to move past the winter peak for respiratory viruses (SARS-CoV-2, RSV, Influenza A) as well as norovirus.

However, RSV levels (national average) are still higher than last year’s peak, and influenza A levels are near last year’s peak. Norovirus still remains at an all time high for the last 3 years of wastewater data. So even though it looks like we may be moving past the peaks, these viruses are still in circulation at very high levels.

Notably, the amount of SARS-CoV-2 in circulation has remained low this winter relative to prior year’s peaks.

I believe the SARS-CoV-2 infection rates may be lower this year because a significantly different variant did not emerge at the start of the fall/winter season. For the last few years new variant(s) have emerged roughly around the time that school starts and have gone on to become the dominant variant driving the winter wave of COVID-19.

The variants this year are all highly similar in the ACE2-receptor binding domain of the Spike protein. Additionally, the SARS-CoV-2 vaccine is very well matched to this year’s variants. Together, this means that prior exposure and vaccination (or both) is capable of driving down infection rates. This is great news, but continued sequencing surveillance is important to ensure that when another variant emerges we can be ready.

Tuberculosis Cases on the Rise in the United States

Kansas is currently fighting the largest Tuberculosis (TB) outbreak recorded in public health history. The case total in this outbreak is currently 68 people.

Separately, an active case of TB has occurred in a student in a West Michigan high school (Kalamazoo County). Health officials in North Carolina are also raising the alarm this week, where they have had 2 years of TB increases after 30 years of declines. Already, the North Carolina health surveillance systems have picked up an unusually high number of cases for 2025. The last time they said they had cases this high, this early in the year was in the 1980s.

TB is often spread in close quarters and/or in prolonged contact with someone who has active TB. In 2023 in the US there was a 15.6% increase in the incidence of TB relative to 2022. The CDC estimates that about 13 M US citizens have latent (non-active) TB, and about 5-10% will develop active TB.

Health officials in North Carolina signaled they believe this increase in rates could be linked to a decrease in people seeking services during the height of the SARS-CoV-2 pandemic. We also know that SARS-CoV-2 disrupts immune system function, and people who have latent (non-active) TB are more likely to develop active TB if their immune system function is compromised. It seems logical that there may be a link between the two. It also seems logical that both a disruption to care as well as infection en masse with a virus that disrupts immune system function may be contributing factors to increased TB rates.

Luckily, TB can be treated, though drug resistant forms are starting to emerge. If you are taking medication for TB it is important to finish the full course of medication and follow your doctors instructions to reduce the chance of developing drug-resistant TB.

Measles in Texas, Could Signal The Start of an Outbreak

Lubbock, Texas reported it’s first measles cases (2) in 20 years this week. Both were in unvaccinated children. In total 4 cases of measles have been reported in Texas in the last two weeks indicating that an outbreak may be developing. Two adults in Harris County last week were the other confirmed measles cases and the Texas Department of State Health Services posted an alert re: places and days that people may have been exposed (below).

These are the first confirmed Measles cases in Texas since 2023.

Measles is a highly transmissible, vaccine preventable illness that can lead to death or life-long complications. Since the height of the pandemic Measles vaccination rates (MMR vaccine) have dropped across the US leaving children in many areas unprotected by herd immunity.

Also vaccine disinformation and hesitancy may be the result of lower vaccination rates.

According to The Texas Tribune: “Since 2018, the requests to the Texas Department of State Health Services for an exemption form have doubled from 45,900 to more than 93,000 in 2024.”

Children having herd immunity to measles also helps protect adults whose vaccine protection can wear off over time or may be diminished due to treatment for cancer or autoimmune disease.

Novel Virus Identified in Shrews in Alabama

Camp Hill virus, named after the Tallapoosa County town where the shews were found, is in the same family (Henipavirus family) as the deadly Hendra and Nipah viruses that have a 70% and 40-75% mortality rate in humans, respectively. Henipaviruses are highly are zoonotic, meaning they are able to spread easily between different animal species including humans.

Researchers found the virus in northern short-tailed shrews collected in 2021, confirming that there is a local animal reservoir for this virus. No human infections with the Camp Hill virus have been reported but other viruses in the same family have caused flu like symptoms some of which may progress to impaired liver or kidney function and/or encephalitis (brain swelling) and death.

Some henipaviruses are not as deadly and do not progress past a flu-like illness for many people. It is unknown if the Camp Hill virus will cause severe disease when infecting people. The original CDC report can be read here.

Thank you for your continued support of this infectious disease newsletter. It is now February 4th, 2025 and the communications embargo has not been fully lifted from the HHS agencies and administrative review is being enforced for public communications. I will summarize what we know about this tomorrow in a special update.