DNA strand intertwined within a brain cell.

Chronic Meningitis Mystery Solved: How Cutting-Edge Tech Found a Hidden Cause

Jordan Keane in Health & Wellness June 2025 • 4 min read.

"A 15-year medical odyssey finally ends with a surprising diagnosis, thanks to metagenomic sequencing."

Imagine battling a health problem for years, with doctors struggling to pinpoint the cause. That was the reality for a 41-year-old woman who experienced chronic relapsing meningitis, a condition where the membranes surrounding the brain and spinal cord become inflamed repeatedly. For 15 long years, she endured recurring episodes of fever, neck stiffness, and pain, with no clear answers in sight.

Traditional diagnostic methods often came back negative, leading doctors down various paths, including treatments for tuberculosis, herpesvirus infections, and inflammatory conditions—all without lasting success. The search for answers took a turn when doctors at UCSF decided to employ a cutting-edge technique called metagenomic next-generation sequencing (mNGS). This advanced technology allowed them to look at all the genetic material in the patient's cerebrospinal fluid (CSF) to identify any potential infectious agents, even those that might have been missed by conventional tests.

The results were astonishing: mNGS identified Taenia solium, the pork tapeworm, as the cause of her chronic meningitis. This discovery led to a diagnosis of neurocysticercosis (NCC), a parasitic disease where cysts form in the brain and spinal cord. With a precise diagnosis in hand, doctors were finally able to start the right treatment, leading to a significant improvement in the patient's health.

The Patient's 15-Year Medical Mystery: A Timeline of Frustration and Hope

DNA strand intertwined within a brain cell.

The patient's journey began at age 26, with episodes of back and neck pain, malaise, and fever. Doctors initially suspected an infection, but standard tests were inconclusive. Despite the lack of definitive proof, she was treated for various conditions, including tuberculosis, due to a recent exposure and a positive skin test conversion.

Her symptoms would resolve temporarily, only to return years later. In 2007, following childbirth and spinal anesthesia, she experienced another flare-up, leading to more tests and treatments. A biopsy revealed lymphohistiocytic inflammation and a non-necrotizing granuloma, further complicating the diagnostic picture. More treatments followed, but the underlying cause remained elusive.

2002: Initial symptoms appear, leading to empirical treatments for various infections.
2007: Symptoms recur after childbirth, with a spinal biopsy revealing inflammation.
2015: A partial thyroidectomy triggers another episode of pain and stiffness.
2017: The patient seeks care at the NIH Neuroimmunology Clinic, where new tests are conducted.

By 2017, the patient's condition had become increasingly difficult to manage. She experienced constant pain, intermittent fevers, and neurological symptoms. Doctors considered autoimmune disorders and other rare conditions, but nothing seemed to fit the puzzle. It was at this point that the team at UCSF decided to use metagenomic sequencing, a bold move that would ultimately solve the mystery.

A New Era in Diagnosis: The Power of Metagenomic Sequencing

This case highlights the incredible potential of metagenomic sequencing to diagnose challenging and rare infections. By analyzing all the genetic material in a patient's sample, mNGS can identify pathogens that traditional tests might miss, leading to faster and more accurate diagnoses. As technology advances and becomes more accessible, mNGS could revolutionize the way we approach complex and undiagnosed illnesses, offering hope to patients who have long searched for answers.

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Everything You Need To Know

What is metagenomic next-generation sequencing (mNGS) and how did it help solve the mystery of the woman's chronic meningitis?

Metagenomic next-generation sequencing (mNGS) is a cutting-edge technology that analyzes all the genetic material in a patient's sample, such as cerebrospinal fluid (CSF). In this case, mNGS was used to identify the cause of the woman's chronic meningitis. Unlike traditional methods, which often came back negative, mNGS was able to identify Taenia solium, the pork tapeworm. This led to a diagnosis of neurocysticercosis (NCC), a parasitic disease that causes cysts in the brain and spinal cord. With a precise diagnosis in hand, doctors were finally able to start the right treatment, leading to a significant improvement in the patient's health.

What were the initial symptoms and diagnostic challenges the patient faced over the 15 years before the correct diagnosis?

The patient's journey began at age 26 with episodes of back and neck pain, malaise, and fever. Doctors initially suspected an infection, but standard tests were inconclusive. Despite the lack of definitive proof, she was treated for various conditions, including tuberculosis, due to a recent exposure and a positive skin test conversion. Her symptoms would resolve temporarily, only to return years later. In 2007, following childbirth and spinal anesthesia, she experienced another flare-up, leading to more tests and treatments. A biopsy revealed lymphohistiocytic inflammation and a non-necrotizing granuloma, further complicating the diagnostic picture. Throughout the 15 years, the patient was treated for various conditions, with the underlying cause remaining elusive. The use of traditional diagnostic methods and the lack of specific findings complicated the identification of the cause, leading to a long and frustrating medical odyssey.

How did the diagnosis of neurocysticercosis (NCC) impact the patient's treatment and recovery?

The diagnosis of neurocysticercosis (NCC), caused by the pork tapeworm Taenia solium, was crucial for the patient's treatment and recovery. Before the correct diagnosis, the patient was treated for various conditions without lasting success. Once NCC was identified through metagenomic sequencing, doctors could start targeted treatment. This specific therapy led to a significant improvement in the patient's health because it addressed the root cause of the chronic meningitis. The treatment likely focused on eliminating the parasitic infection and managing the inflammation caused by the cysts in the brain and spinal cord.

What is the significance of this case in terms of the future of diagnosing mysterious illnesses?

This case underscores the potential of metagenomic sequencing to revolutionize the way we diagnose challenging and rare infections. By analyzing all genetic material in a patient sample, mNGS can identify pathogens that traditional tests might miss, leading to faster and more accurate diagnoses. This is particularly important for illnesses where the cause is elusive or the pathogen is difficult to detect using conventional methods. As technology advances and becomes more accessible, metagenomic sequencing offers hope to patients who have long searched for answers and could lead to more effective treatments and better patient outcomes in the future.

What were the key milestones in the patient's 15-year medical journey, and how did they contribute to the eventual diagnosis?

The patient's journey included several key milestones that highlighted the diagnostic challenges. In 2002, initial symptoms appeared, leading to empirical treatments. In 2007, symptoms recurred after childbirth, with a spinal biopsy revealing inflammation. In 2015, a partial thyroidectomy triggered another episode of pain and stiffness, further confusing the diagnostic picture. By 2017, after seeking care at the NIH Neuroimmunology Clinic, new tests were conducted, but the underlying cause remained unknown. The application of metagenomic sequencing in 2017 proved to be the breakthrough, finally identifying the Taenia solium tapeworm and the neurocysticercosis that caused the chronic meningitis. These milestones demonstrate the progressive nature of the illness and the challenges in diagnosis prior to the use of advanced technology.