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July 7, 2023

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Fungal Meningitis Outbreak

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As of June 1, 2023, a serious multistate outbreak of fungal meningitis is ongoing in the U.S. among patients who underwent procedures involving epidural anesthesia in two clinics in Mexico. In this article, learn more about: who is at risk, what screening and diagnostic steps should be taken for exposed patients, what is the presentation and what management is recommended.

Medical Care Abroad

Each year more than 15 million U.S. citizens go abroad for medical and surgical treatment or procedures, often for reduced cost and more rapid access and scheduling. This is an over $50-billion-dollar-a-year industry known as “Medical Tourism.” Occasionally, serious complications are encountered by these individuals after returning home for recovery. The most common serious complications are infections after surgical procedures. This can result in patients with rare and unusual infections being encountered throughout the country.

International Infection Prevention and Control (IPC) and Medical Tourism

Infection Prevention and Control (IPC) processes are applied at high-quality clinics globally. IPC is a collaborative process requiring specific knowledge, process education and adherence to protocols of the entire healthcare team. As such, a single weak link in the IPC process negates the efforts and expertise of even the best healthcare team. Unfortunately, the quality and adherence to IPC measures are not consistent across many regions internationally.

The number of clinics catering to medical tourists is rapidly increasing, and many are in countries with little public health enforcement or IPC capacity. In addition, medical record-keeping and patient identification across international boundaries is typically below standard, making adequate medical care addressing complications or infectious outbreaks once the patient arrives home problematic. Another complicating factor is that some patients obtain their care abroad to maintain anonymity. Patients may be reticent to disclose the nature or location of their treatments to clinicians after returning to the U.S.

Who is “At Risk” or “Exposed”?

The patients involved in this current fungal meningitis outbreak received their care at two clinics in the city of Matamoros, Mexico. The locations involved are the River Side Surgical Center and Clinica K-3. These clinics were closed by Mexican Public Health authorities on May 23, 2023, when the problem was first detected. Patients who received care involving epidural anesthesia at these clinics from January 1, 2023, through May 23, 2023, are at risk.

The CDC and Mexican Public Health authorities are working to identify and contact all at-risk patients. Among the recommendations being given to at-risk patients is to report to their local emergency department for evaluation and workup, including a lumbar tap (LP), even if patients are asymptomatic. Patients are also specifically recommended to present to emergency departments for any signs or symptoms consistent with fungal meningitis.

Current Status of the Outbreak

Several laboratories in the U.S. have detected fungal signals consistent with the organism Fusarium solani in the cerebrospinal fluid (CSF) of mostly asymptomatic patients during follow-up care when LPs were obtained on exposed patients. Currently there are around 212 Americans in 25 states known to be at risk for fungal meningitis from exposure at these clinics.

In addition, at least six patients demonstrated elevated levels of beta-D-glucan, another biomarker of fungal infection. Among identified patients, 142 people are under investigation, 18 are suspected to be infected, 10 have been determined as a probable case and six are confirmed cases. Four of these patients have died, a crude Case Fatality Rate (CFR) of 11%, consistent with previously reported fatality rates from other fungal species with treatment in neurosurgical patients.

Fungal Meningitis Characteristics

Depending on the organism, the incubation period for fungal meningitis is typically reported as 30 to 180 days post exposure after neurosurgical procedures. However, in some fungal species, the incubation period may be much longer. The Fusarium species complex has been responsible for previous outbreaks of fungal meningitis with very high (>48%) case fatality rates.

The primary factors associated with higher mortality from these organisms in central nervous system infections include delay in diagnosis, delay in treatment, host immunosuppression, mycotoxic toxin generation and the availability of appropriate treatment regimes.

Clinical Presentation of Fungal Meningitis

Although the signs and symptoms of fungal meningitis are usually consistent with other causes of meningitis, the findings are typically slower to develop and more subtle initially. This is primarily due to the usually slower growth of the organism. Low grade fever, headache, photosensitivity, neck stiffness, meningeal signs, irritability, malaise, myalgia and alteration in mental status are often reported. Any such symptoms in patients exposed should trigger not only the recommended LP workup, but MRI imaging and initiation of treatment, due to the higher lethality caused by a delay in treatment.

How Should Patients be Managed Diagnostically?

CDC recommendations for all exposed patients – both symptomatic and asymptomatic include:

  • Diagnostic lumbar puncture (LP), unless an absolute contraindication exists
  • Brain imaging by MRI with and without contrast for symptomatic patients or those with abnormal LP studies, which should not be delayed to obtain imaging
  • MRI spine imaging with and without contrast for patients with back pain or paresthesia
  • Collect extra CSF for storage and further testing that may be needed
  • Opening pressure and routine cell counts, protein, glucose and lactate
  • Bacterial, mycobacterial, and fungal stains and cultures
  • Beta-d-glucan (Fungitell®) and Aspergillus galactomannan
  • CSF for pan-fungal PCR testing or metagenetic testing

Fungal Meningitis Outbreak

Clinicians should keep these rare but serious infections in mind when evaluating patients in the ED, clinic or hospital. Triage, nursing and support staff need to have an awareness of this outbreak and appropriately screen all patients for exposure.

All patients exposed at the two clinics in the city of Matamoros, Mexico, (River Side Surgical Center and Clinica K-3) between January 1, 2023, through May 23, 2023, should have an LP and workup as indicated by the CDC and/or state guidelines.

Living in a global biologic society, patients should always be asked about recent travel and any potential exposures—including surgical or medical treatments associated with Medical Tourism. This is particularly important in the context of currently emerging infectious diseases. With the large number of Americans obtaining care abroad, the risk for these unusual infections can be spread across the nation. Access a full list of resources here.