Welcome to the ninth edition of FOI Clinical. Each week, we'll send you a briefing on outbreak news. When something urgent breaks, you'll get an alert the same day.

In this edition

Measles - Sexually transmitted Shigellosis - Typhus in California - Plague in New Mexico - Mpox in Germany

National interest

Measles

As of April 2, 2026, there have been 1,671 confirmed cases, up 96 from the week before. The largest case totals continue to be in South Carolina, Utah, Florida, and Texas, though Utah is currently a focal point for new transmission.

The rate of new cases has dwindled, with the South Carolina outbreak effectively over, and the outbreak in Florida slowed. However, this is not the end of the measles resurgence. New clusters will likely emerge in the weeks and months ahead.

• South Carolina: No new cases have been reported since the week of March 8. If no new cases are reported, the outbreak is approximately two weeks away from being declared over.
• Utah: Case counts are climbing rapidly in Utah. There have been 378 cases reported this year, bringing the outbreak total to 575. Another 60 cases were reported last week, double the number reported the week before. While the largest case totals continue to be in Southwest Utah (242), cases have been reporting in areas covered by 11 local health departments, including Utah County (87), Salt Lake County (60), TriCounty (56), and Central Utah (46). There have been more than two dozen exposure locations reported in the past few weeks, including at more than one Walmart location, multiple University of Utah buildings, and numerous clinics and hospitals.
• Texas: As of April 1, there have been 175 confirmed cases. All five of the new cases are associated with federal detention facilities in Hudspeth County (135 total cases have been reported so far in federal detention facilities in the county).
• Florida: New cases appear to be slowing in Florida; as of March 28, there were 144 confirmed cases, an increase of 1 from the week before. The vast majority of cases have been in Collier County (106); while 12 other counties have reported cases, the totals remain in the single digits.
• Arizona: The outbreak along the border with Utah continues, rising to 77 for 2026, and 291 for the total outbreak. 11 new cases were reported in the last week in March.
• North Dakota: As of April 1, 27 cases and 5 hospitalizations have been confirmed in the state this year. After several weeks with no reported cases, 5 were reported between March 23 and April 1, all in Ransom County. However, most cases so far this year in the state (23) have been associated with an outbreak in Pembina County. There have also been single cases reported in Williams, Traill, and Walsh Counties.
• Oregon: 13 cases have been reported in the state this year, 6 since the start of March. The state did not report any cases in 2024 or 2025. Most of the reported cases appear to have been locally acquired, but have not been epidemiologically linked to each other, which suggests there is ongoing community spread that is not being detected.

Sexually transmitted shigellosis

Shigellosis is increasingly being reported as spreading through sexual networks, particularly among men who have sex with men (MSM). The UK Health Security Agency recently reported that in 2025, there were 2,560 cases of sexually transmitted shigellosis, a higher rate than in either of the prior two years.

Case reports are not currently elevated in the United States, according to data from the National Notifiable Disease Surveillance System.

Infection with one of four species of Shigella bacteria produces shigellosis. It is spread via the fecal-oral route, and can be acquired through contaminated food, water, or surfaces or through direct contact. Importantly, particularly for sexual transmission, bacterial shedding in stool can continue for roughly two weeks after symptoms resolve.

Welcome to the eighth edition of FOI Clinical. Each week, I'll send you a briefing on outbreak news. When something urgent breaks, you'll get an alert the same day.

In this edition

Measles - Mumps - Haemophilus influenzae - Tularemia in CA - Tetanus in CA - Hepatitis A in Italy

National interest

Measles

As of March 27, 2026, there have been 1,575 cases, up 88 from last week. The largest case totals continue to be in South Carolina, Utah, Florida, and Texas.

The rate of new cases has dwindled, with the South Carolina outbreak effectively over, and the outbreak in Florida slowed. However, this

Welcome to the seventh edition of FOI Clinical. Each week, I'll send you a briefing on outbreak news. When something urgent breaks, you'll get an alert the same day.

In this edition

Measles - Seasonal respiratory illness update - Mpox in Missouri - Hantavirus pulmonary syndrome in New York - Leptospirosis in Ohio, territories - Meningitis in the UK

National interest

Measles

As of March 19, 2026, there have been 1,487 confirmed cases of measles this year. Thirty-two states have reported cases. The largest case totals are in South Carolina, Utah, Florida, and Texas.

Several notable outbreaks are underway. The list below is not comprehensive, but rather a selection of prominent active clusters worth keeping in mind.

• South Carolina: As of March 24, there have been 997 confirmed cases in a multi-county outbreak. There have been no new cases reported since the last edition of FOI Clinical.
• Arizona/Utah: The outbreak in Utah is growing quickly. There have been 486 confirmed cases, an increase of 38 from last week. All local health departments in the state have reported cases, with the majority of cases reported in Southwest Utah (n = 233), Utah County (n = 78), Salt Lake County (n = 53), and Central Utah (n = 36). The virus is present in wastewater samples around the state, confirming active community spread. Exposed locations are listed here. The outbreak in Arizona is growing more slowly; there have been 2 new cases reported in the last week, raising the total for the outbreak to 280.

Welcome to the sixth edition of FOI Clinical. Each week, I'll send you a briefing on outbreak news. When something urgent breaks, you'll get an alert the same day.

In this edition

Measles - Seasonal Respiratory Infections - Interim Flu VE - Expanded RSV Vax Approval - Hantavirus in New Mexico - Infant Formula Recall Outside US - Meningitis in the UK

National interest

Measles

As of March 12, 2026, there have been 1,362 confirmed cases of measles this year, up 81 from the week prior. Thirty-one states have reported cases. The largest case totals are in South Carolina, Utah, Florida, and Texas.

Several notable outbreaks are underway. The list below is not comprehensive, but rather a selection of prominent active clusters worth keeping in mind.

• South Carolina: The multi-county outbreak in South Carolina has 997 confirmed cases to date. The outbreak has slowed considerably, with 7 new cases confirmed in the past two weeks.
• Arizona/Utah: The apparent slowdown over the past couple of weeks was a mirage. Cases have shot up in Utah, with more cases reported during the last week in February (44) than in any prior week in the outbreak (data reporting is a few weeks delayed for the state). This brings the total for 2026 to 209 and the outbreak total to 405, meaning more cases have now been reported this year than last year. More than 150 people (nearly 40%) have gone to the emergency department for measles during this outbreak, according to the state's epidemiologist. Exposed locations are listed here. Increasing vaccination rates is proving challenging, particularly in the heavily-affected southwestern part of the state. In contrast, Arizona has not reported any new cases in March, and the total remains at 276 for the outbreak.

Welcome to the fifth edition of FOI Clinical. Each week, I'll send you a briefing on outbreak news. When something urgent breaks, you'll get an alert the same day.

In this edition

Measles updates - H5N1 - Mumps - Seasonal respiratory viruses - Viral hemorrhagic fever

Measles

Latest epidemiology

As of March 5, 2026, there have been 1,281 confirmed cases, up 145 from the week prior. 31 states have reported cases so far this year. The largest case totals have been reported in South Carolina, Utah, Florida, and Texas.

Updates on Hotspots

Several notable outbreaks are underway. The list below is not comprehensive, but rather a selection of prominent active clusters worth keeping in mind.

Flu, Covid-19, and RSV vaccine effectiveness data for this season is starting to come in. FOI Clinical has pulled out the key numbers you need for patient counseling and end-of-season decision-making. These numbers can help you set realistic expectations with patients and answer the question, "did my flu shot even work?"

So far, effectiveness looks similar to a typical year, even with the emergence of the new H3N2 subclade K. As always, effectiveness depends on how well circulating strains match the vaccine composition.

Influenza

This season, adults: Canadian researchers estimated how well this season's flu vaccine is working against H3N2, the dominant flu strain circulating this season. Using data from four provinces, they found the vaccine reduced the risk of a doctor visit for H3N2 flu by roughly 40%. Like the United States, Canada predominantly uses egg-based vaccines.

This season, adults: UK Health Security Agency estimated around 75% effectiveness against

The Centers for Disease Control and Prevention (CDC) is investigating a multistate outbreak of extensively drug-resistant Salmonella infections linked to Rosabella brand moringa powder capsules distributed by Ambrosia Brands, LLC.

Seven cases have been reported across seven states, with three hospitalizations and no deaths as of February 13. The outbreak strain is resistant to all first-line and alternative antibiotics commonly recommended for Salmonella, and carries an NDM-1 carbapenemase gene, meaning it may also be resistant to carbapenems. According to CDC, this is the first documented outbreak of Salmonella with an NDM-1 gene in the United States.

The capsules are sold in white plastic bottles with a green label, covering 52 lot codes with 2027 expiration dates. The product was available nationwide primarily through the company's website, Amazon, TikTok Shop, Shein, and eBay. The firm has agreed to a voluntary recall. Specific lot codes are available on FDA's website.

This is

FOI Clinical is a resource from the team behind Force of Infection, trusted by 46,000 readers for flu, Covid-19, RSV, and norovirus tracking.

We track outbreaks and disease activity, then send you detailed reports on what's relevant to your practice. 

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In it's first month, 96% of FOI Clinical survey respondents reported that the reports were useful. FOI Clinical has been featured in Medscape and NPR.

In September 2022, Force of Infection gave early warning of what became the tripledemic. In October 2025, we warned that the 2025–2026 flu season was shaping up to be big. We gave readers weeks of lead time before it hit the news or their communities.

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