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When did the cyclosporiasis outbreak start?
Cyclosporiasis cases top 3,000
Alert: Cyclospora cayetanensis: Multistate Outbreak with Midwest Epicenter
FOI Clinical - Issue 22
FOI Clinical - Issue 21
FOI Clinical - Issue 20
Advisory: Bundibugyo ebolavirus outbreak and hantavirus update
Advisory: Andes Hantavirus – MV Hondius Cruise Ship Outbreak
More on RSV activity
FOI Clinical - Issue 8
FOI Clinical - Issue 7
FOI Clinical - Issue 6
FOI Clinical - Issue 5
Seasonal Vaccine Effectiveness: What the Data Shows
Alert: Extensively Drug-Resistant Salmonella Linked to Moringa Powder Capsules
What to expect
This information is made available as a public service. To support our work and receive weekly updates on outbreak-prone disease activity, consider upgrading. We also have a general-reader publication, Force of Infection.
Tracking cyclosporiasis is more difficult than tracking some infectious diseases, because standard GI workups do not routinely include testing for cyclosporiasis. Typically, providers must suspect the diagnosis to order testing. This creates a detection bias that distorts surveillance, because it is sensitive to clinician awareness.
Michigan, for example, has a much higher number of cyclosporiasis cases at 2,640 than the second-most affected state, New York (470). This fivefold difference does not necessarily reflect a true difference in disease burden. A more likely explanation is that awareness of the outbreak is higher in Michigan which is driving a feedback loop. More awareness prompts more testing which leads to more detection and reporting.
When detection
This information is made available as a public service. To support our work and receive weekly updates on outbreak-prone disease activity, consider upgrading. We also have a general-reader publication, Force of Infection.
According to state-level estimates compiled by FOI Clinical, cumulative cyclosporiasis reports now exceed 3,300 nationwide (year-to-date, not confirmed outbreak-related). For context, a typical year sees 3,000 to 4,000 cyclosporiasis cases reported to the National Notifiable Disease Surveillance System. No source has been identified yet.
Michigan remains most affected at 1,562, followed by New York (470) and Ohio (364). At least 500 additional cases have been reported in the last day, including more than 300 in Michigan. Data from the Michigan Department of Health & Human Services show that outbreak signals began in late June and have accelerated steadily since.
According to CDC, which
FOI Clinical issues two types of rapid communications: alerts for highest priority information, and advisories for emerging events clinicians should be aware of. This is an alert.
Update July 13: When did the cyclosporiasis outbreak start?
Update July 11, 2026: Cyclosporiasis cases top 3,000
A rapidly expanding multistate Cyclospora cayetanensis outbreak has its epicenter in southeast Michigan and northwest Ohio, according to current reports. As of July 8, Michigan has received more than 700 reports of cyclosporiasis, including 38 hospitalizations since June 22. This is approximately 14 times the state's annual average. Ohio reports 177 cases across 43 counties (last updated July 7, per ODH spokesperson), with spread throughout central and northwest Ohio.
The effects extend beyond the Midwest. At least 18 states are affected nationally; aggregated state-level reporting suggests a true national burden well above 1,200
Welcome to the twenty-second 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.
Tularemia – Measles – Brucellosis: California – Mumps: Maryland – Malaria: Maryland – Legionnaires: NYC – Grand Canyon unknown – Powassan: New England – Plague rule out – Ebola – Marburg – Measles in the Americas
Peak season is underway; 78% of annual U.S. tularemia cases occur May–September. Reports this year are lower than during the same period last year, with 38 cases reported vs. 95 prior year (0.4x). The below-baseline count may partly reflect a January 2026 case definition revision (CSTE 25-ID-09) that tightened probable case criteria.
The 2025 MMWR published the first tularemia treatment update since 2001. Key changes:
Francisella tularensis is a Tier 1 Select Agent with an infectious dose of <10 organisms by inhalation.
CDC updated to 2,170 confirmed cases on July 2, up 36 from last week, across 41 jurisdictions. The 2026 year to date total is now 119 cases short of matching all of 2025 (2,289 full-year) with five months remaining; the PAHO elimination-status review convenes in November.
State updates:
California accounts for 16 of 37 national brucellosis cases year to date (43%), well above its historical ~21% share. LA County DPH announced a South Los Angeles County cluster of Brucella melitensis infections on May 23, linked to unpasteurized cheese imported from Mexico. No brand has been publicly named and no recall has been issued.
B. melitensis, responsible for 57% of CDC-tested U.S. isolates, is almost exclusively associated with small ruminant dairy (goat, sheep). Mexico accounts for 58% of travel-linked U.S. brucellosis cases. Clinicians in Southern California should ask about raw dairy consumption in patients presenting with undulant fever, arthralgia, or unexplained hepatitis.
Maryland accounts for 49 of 122 national mumps cases to date (40.2%), concentrated in Baltimore City and surrounding counties (Anne Arundel, Baltimore County, Carroll, Harford, Howard, Queen Anne's). The cluster has been active since February 2026, when the Maryland Department of Health (MDH) announced 26 cases, six times the full-year 2025 total, and has grown steadily since with no common exposure identified.
Welcome to the twenty-first 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.
Infant botulism: Nara Organics – Cyclosporiasis – Measles – Mpox – Powassan virus: New England – Plague: Arizona – Ebola – Nipah: India – Measles: Americas/World Cup – Notable declines
The FDA and CDC are investigating a multistate infant botulism outbreak involving three confirmed cases in California, Pennsylvania, and Washington, all male infants aged 2–5 months, illness onset April–May 2026, all hospitalized, no deaths. All three consumed Nara Organics Whole Milk Organic Powdered Infant Formula; toxin type A was identified in each. Nara Organics recalled all infant formula on June 13 based on epidemiological evidence, before laboratory contamination was confirmed. No new cases have been added since the initial notice.
The critical finding in the June 26 update: traceback identified Organic West Milk as the raw milk supplier and Dairy Farmers of America as the spray-drying processor, the identical supply chain implicated in the November 2025 ByHeart infant formula botulism outbreak (28 confirmed, 20 probable cases across 19 states; declared over March 4, 2026). Organic West Milk had provided an incomplete customer list during the 2025 investigation that omitted Nara Organics, raising concern that additional exposed brands may remain unidentified. The formula manufacturer is Milchwerke Mittelelbe GmbH (Elb-Milch, Germany); FDA has inspected both European production facilities and issued deficiency observations. An additional suspected toxin type A case in an infant in Puerto Rico is under investigation.
This is the second product-associated infant botulism outbreak within eight months involving overlapping supply chain actors, a pattern suggesting a persistent contamination point at the raw milk or spray-drying stage rather than an isolated manufacturing event. Environmental confirmation from product testing is still pending.
An active Cyclospora cayetanensis outbreak is generating significant national attention. The CDC line list reports 145 domestically acquired cases across 17–20 states (last updated June 16), with illness onset May 1–June 7, 20 hospitalizations, and no deaths. During the most recent reporting week, the National Notifiable Disease Surveillance System saw 73 cases reported in a single week putting year to date totals at 589 cases (1.2x prior year). The outbreak is running well past the typical early-season acceleration.
gWelcome to the twentieth 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.
Cyclosporiasis - Measles - Mpox - Influenza: Lackland AFB - Salmonella: backyard poultry - Norovirus: Appalachian Trail - Chikungunya - Below-baseline declines - Ebola - Hantavirus
During the most recent reporting week, 64 cases were reported to the National Notifiable Disease Surveillance System, up from 48 the week prior and 20 two weeks ago. Year to date, 424 cases have been reported (1.3x prior year). The FDA is still investigating an active outbreak with an unknown food source. We covered the early acceleration in Issue 19.
CDC reports 2,104 confirmed cases as of June 18, up 31 in one week, across 41 jurisdictions (Connecticut added).
State dashboard updates:
Year to date, 640 cases have been reported (1.3x prior year). CDC's situation summary (updated June 1) notes >20 laboratory-confirmed clade I cases in the U.S. since November 2024, all linked to travel. Several Western European countries are now reporting clade Ib cases with no documented travel history, indicating local sexual transmission. Clade II remains at low levels but fall 2025 marked the highest monthly counts since 2022.
During Pride Month, several cities expanded mpox vaccination access in response to rising case counts. Boston's public health commission flagged an uptick in cases citywide and nationally, offering walk-up JYNNEOS doses at Pride events and scheduling additional clinics through the summer. The push comes after the CDC in late May removed its "Safer Sex, Social Gatherings, and Monkeypox" webpage, the primary federal guidance on reducing mpox risk at Pride events, sex clubs, and high-contact settings, despite a July 2025 federal court order requiring restoration of removed LGBTQ+ health information.
FOI Clinical issues two types of rapid communications: alerts for highest priority information, and advisories for emerging events that clinicians should be aware of. This is an advisory.
WHO declared a Public Health Emergency of International Concern on May 17 over an escalating Ebola outbreak centered in Ituri Province, DRC; the country's 17th recorded Ebola epidemic.
The causative agent is Bundibugyo ebolavirus (BDBV), first identified in Uganda in 2007. This is the critical distinction from recent outbreaks: there is no approved vaccine or therapeutic for BDBV. Existing vaccines (Ervebo) and monoclonal antibodies (Ebanga, Inmazeb) target the Zaire species and are not thought to be effective.
The earliest suspected case was in a healthcare worker in Bunia who developed symptoms on April 24 and died three days later. The outbreak now spans 9 health zones in Ituri Province, with U.S. CDC reporting 675 suspected, probable and confirmed cases and 134 deaths, as of May 19. Case counts have grown very rapidly over the last few days, as health officials work to determine the true scope of the outbreak.
The outbreak has spread beyond Ituri: confirmed cases have appeared in Goma and Kinshasa, and 2 confirmed cases (1 death) in Uganda, travelers from DRC in Kampala with no apparent epidemiological link to each other. Both had a travel history to the affected area.
As of May 7, 2026
An outbreak of Andes hantavirus (Orthohantavirus andesense) is underway aboard the MV Hondius, a Dutch-flagged expedition cruise ship that departed Ushuaia, Argentina on April 1, 2026. As of May 7, there are 8 reported cases (5 laboratory-confirmed, 3 suspected), including 3 deaths. The virus has been confirmed as the Andes strain, the only hantavirus known to transmit person to person, by South Africa's National Institute for Communicable Diseases and Geneva University Hospitals.
The MV Hondius carried 147 people (88 passengers, 59 crew) of 23 nationalities, including 17 Americans. The ship is currently en route to Tenerife, Canary Islands, where it is expected to dock on May 11. Upon arrival, non-Spanish passengers will be repatriated; 14 Spanish nationals will be quarantined at a military hospital in Madrid.
A Swiss passenger who had disembarked and returned home was confirmed positive at University Hospital Zurich.
Several other reports are being investigated. Two Singaporean passengers (men in their 60s) are isolated at Singapore's National Centre for Infectious Diseases; one has a runny nose, the other is asymptomatic. A KLM flight attendant in the Netherlands has been hospitalized at Amsterdam UMC with mild symptoms who reportedly had contact with an infected passenger has been ruled out, according to Inside Medicine.
WHO assesses the global risk as low. WHO Director-General Tedros Ghebreyesus has stated that more cases may emerge in the coming weeks due to the virus's long incubation period (up to 8 weeks), but confirmed on May 7 that no additional passengers beyond the identified cases have reported symptoms. WHO has deployed an expert on board for a comprehensive medical assessment and arranged shipment of 2,500 diagnostic kits from Argentina to laboratories in five countries.
One hypothesis is that the Dutch couple who became the first two cases contracted the virus before boarding, during a bird-watching trip through Argentina, Chile, and Uruguay that included sites where the long-tailed pygmy rice rat (Oligoryzomys longicaudatus), the natural reservoir for Andes virus, is present.
This table reflects publicly available details about reported cases, to the best of our knowledge. This information should be considered preliminary.
| # | Nationality | Status | Key details |
|---|---|---|---|
| 1 | Dutch, M, 70 | Suspected; died (April 11) | Died on board; probable index case. Death initially attributed to natural causes; posthumous confirmation pending. |
| 2 | Dutch, F, 69 | Confirmed; died (April 26) | Wife of case 1; flew from Saint Helena to Johannesburg on April 25; briefly boarded KLM Flight 592 but was removed before departure due to deteriorating condition; died at hospital the following day. Confirmed by NICD South Africa (PCR, May 4). |
| 3 | German, F | Suspected; died (May 2) | Died on board; developed fever on April 28 and presented with pneumonia. Cause of death under investigation. |
| 4 | British, M | Confirmed; critical | Evacuated from Ascension Island to South Africa on April 27. Confirmed by NICD South Africa. Transferred to Leiden University Medical Center (Netherlands). |
| 5 | May 5 evacuee | Confirmed | Confirmed at Radboud University Medical Center (Netherlands) by RIVM, May 7. |
| 6 | May 5 evacuee | Confirmed | Confirmed at Leiden University Medical Center (Netherlands), May 7. |
| 7 | May 5 evacuee | Suspected | Evacuated to Dusseldorf, Germany; reported not showing symptoms but evacuated due to close contact with case 3. Has since returned to Germany. |
| 8 | Swiss, M | Confirmed | Disembarked before outbreak recognized; confirmed Andes strain at University Hospital Zurich via Geneva HUG reference lab. |
Illness onset ranged from April 6 to April 28. Clinical presentation has included fever, gastrointestinal symptoms, and rapid progression to pneumonia, acute respiratory distress syndrome (ARDS), and shock.
The CDC stated on May 6 that "the risk to the American public is extremely low.” Former passengers are being monitored in at least three states:
None have shown symptoms as of May 7.
Risk to the U.S. general public: extremely low.
The 2025–2026 RSV season in the United States has followed an atypical trajectory. Elevated RSV activity did not begin until December 2025, and the season peaked in late February 2026, roughly 8 weeks later than the 2023–24 season. Peak hospitalization rates were lower than either of the two preceding seasons. As of late March 2026, RSV activity is declining nationally but remains elevated in several regions, particularly the Mountain West.
In response to the prolonged season, 48 of 66 federally funded immunization programs have extended nirsevimab (Beyfortus) eligibility through April 30, 2026.
Disease severity among hospitalized patients has been comparable to recent seasons. The shift is in timing, not in clinical presentation.
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.
Measles - Mumps - Haemophilus influenzae - Tularemia in CA - Tetanus in CA - Hepatitis A in Italy
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 is not
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.
Measles - Seasonal respiratory illness update - Mpox in Missouri - Hantavirus pulmonary syndrome in New York - Leptospirosis in Ohio, territories - Meningitis in the UK
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.
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.
Measles - Seasonal Respiratory Infections - Interim Flu VE - Expanded RSV Vax Approval - Hantavirus in New Mexico - Infant Formula Recall Outside US - Meningitis in the UK
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.
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.
Measles updates - H5N1 - Mumps - Seasonal respiratory viruses - Viral hemorrhagic fever
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.
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.
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
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
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.
During two
