A novel case of disseminated blastomycosis in China

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A novel case of disseminated blastomycosis in China

Global travel connects us across continents—but it also carries rare, region-specific diseases to new places. For a 25-year-old Chinese overseas student returning from 4 years in Vermont (a U.S. state where blastomycosis is endemic), a seemingly mild “cold” quickly escalated into a life-disrupting infection: disseminated blastomycosis, a fungal disease rarely seen in China. Here’s how doctors solved the mystery—and what it teaches us about diagnosing imported illnesses.

The Case: A “Cold” That Worsened

The patient, a healthy man with no prior medical history, returned to China from Vermont three weeks before his symptoms started. He first went to a clinic with fever, cough, and left knee pain, where he was diagnosed with a cold and given painkillers and oral antibiotics. But his symptoms didn’t improve—instead, his knee swelled so much he could barely walk, and red, painful rashes appeared on his legs. These rashes grew into clusters of swellings, pustules, and eventually burst into pus.

At a municipal hospital in Hangzhou, a chest CT scan revealed abnormal high-density areas in his left lung and hilum (the area where airways enter the lung). Blood tests showed signs of severe inflammation: a white blood cell count of 11.6 × 10⁹/L (normal: 4–10), 88.2% neutrophils (normal: ~40–75%), and a C-reactive protein (CRP) level of 70.3 mg/dL (normal: <10). Doctors diagnosed community-acquired pneumonia and prescribed moxifloxacin, a broad-spectrum antibiotic—but after a week, he felt worse. His liver enzymes (alanine transaminase, ALT, and aspartate transaminase, AST) spiked to 191 U/L and 121 U/L (normal: ~7–56 U/L), his white blood cell count rose to 16.6 × 10⁹/L, and his CRP hit 213 mg/dL. His knee pain became unbearable, and his skin lesions spread.

The Diagnostic Journey: Uncovering the “Great Pretender”

Frustrated by the lack of progress, the patient was transferred to the First Affiliated Hospital of Zhejiang University’s School of Medicine. Here, doctors dug deeper:

  • Bronchoscopy biopsy: A sample from his airway lining showed yeast spores with thick, double-refractile walls—classic signs of a fungal infection.
  • Joint and skin tests: Doctors drained 25 mL of brown, bloody fluid from his knee and collected pus from his skin lesions. Microscopic exams revealed round spores in both samples.
  • Next-generation sequencing (NGS): To confirm the pathogen, they used NGS—a fast genetic test that reads DNA—to analyze the skin pus. The result: 57 sequences matching Blastomyces dermatitidis, the fungus that causes blastomycosis.

Tests for tuberculosis (T-SPOT.TB) and other fungi (like Cryptococcus) came back negative, ruling out other common infections.

What Is Blastomycosis?

Blastomycosis is caused by inhaling spores from Blastomyces dermatitidis, a fungus that lives in soil and rotting wood near lakes and rivers. It’s endemic to parts of North America—especially the St. Lawrence-Great Lakes and Mississippi River systems—and is nicknamed the “great pretender” because it mimics pneumonia, tuberculosis, or even cancer. This makes it extremely hard to diagnose, especially in non-endemic areas like China.

Before this case, only 9 blastomycosis cases had been reported in China. Most were in young men (7 out of 9) who had traveled to endemic regions, though a few had no travel history—suggesting sporadic local cases.

Treatment: Posaconazole as a Lifeline

Guidelines from the Infectious Diseases Society of America (IDSA) recommend oral itraconazole for mild-to-moderate disseminated blastomycosis and amphotericin B for severe cases. But this patient’s liver enzymes were already elevated, so doctors chose posaconazole—a newer antifungal with fewer liver side effects.

The results were dramatic:

  • Within 10 days, a follow-up chest CT showed significant improvement in his lung lesions.
  • His cough and knee pain lessened, and his skin lesions began to crust over.
  • After 3 weeks, he was discharged on oral posaconazole.

He took the drug for 9 months, with monthly follow-ups showing steady recovery: his lung lesions cleared, his knee function returned, and his liver enzymes stabilized.

Key Lessons for Travelers and Doctors

This case highlights three critical takeaways:

  1. Travel history saves lives: The patient’s 4-year stay in Vermont—an endemic area—was the key clue linking him to Blastomyces dermatitidis. Doctors must always ask about where patients have lived or visited.
  2. NGS speeds up rare diagnoses: Standard tests (like blood cultures) often miss rare fungi. NGS, which reads the pathogen’s DNA, provided a definitive answer in days.
  3. Posaconazole works for blastomycosis: While it’s not first-line, posaconazole was a safe, effective option for this patient—offering hope for others with liver issues or limited access to other drugs.

Why This Matters

As global travel increases, imported cases of blastomycosis will become more common in non-endemic countries like China. This case reminds us that “common” diseases (like colds or pneumonia) aren’t always the answer—and that staying curious about a patient’s story (and their travels) can unlock the truth.

Original study by Meng-Jiao Fu, Hua Zhou, Wen-Jiang Ma, Qing Yang, Bao-Lang Leng, and Xuan-Li Xu from the First Affiliated Hospital of Zhejiang University and Hangzhou Third Hospital. Published in the Chinese Medical Journal in 2019.

References:

  1. Chen G, Shen DX, Luo YP, Gao W. A case of pulmonary and cutaneous blastomycosis (in Chinese). Chin J Lab Med 2010;33:467–468. doi: 10.3760/cma.j.issn.1009-9158.2010.05.023.
  2. Chen ZJ, He Q, Wang X, Wang Y, Yan SZ, Tian L, et al. A case of pulmonary blastomycosis (in Chinese). Chin J Infect Dis 2016;34:365–366. doi: 10.3760/cma.j.issn.1000-6680.2016.06.012.
  3. Zhao TM, Gao J, She DY, Chen LA. Blastomycosis in China: a case report and literature review. Chin Med J 2011;124:4368–4371. doi: 10.3760/cma.j.issn.0366-6999.2011.24.044.
  4. Zhu D, Chen H, Yu L. Probable pulmonary blastomyomycocis in an immunocompetent person. Int J Infect Dis 2017;59:86–89. doi: 10.1016/j.ijid.2017.04.006.
  5. Chapman SW, Dismukes WE, Proia LA, Bradsher RW, Pappas PG, Threlkeld MG, et al. Clinical practice guidelines for the management of blastomycosis: 2008 update by the Infectious Diseases Society of America. Clin Infect Dis 2008;46:1801–1812. doi: 10.1086/588300.
  6. Proia LA, Harnisch DO. Successful use of posaconazole for treatment of blastomycosis. Antimicrob Agents Chemother 2012;56:4029. doi: 10.1128/Aac.00359-12.

doi.org/10.1097/CM9.0000000000000566

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