Emerging Zoonotic Cutaneous Sporotrichosis in Thailand: Clinical Insights, Antifungal Resistance, and Treatment Successes

Understanding Sporotrichosis

What is Sporotrichosis?

Sporotrichosis is a chronic fungal infection caused by Sporothrix spp. fungi. These fungi can take on two forms: a hyphal form at lower temperatures and a budding yeast form at higher temperatures. They live in soil, plants, and organic matter, mainly affecting the skin and tissues after injury from contaminated sources.

Types of Sporothrix spp.

Previously, the primary fungus in this category was S. schenckii, but it has been reclassified to include several species like S. brasiliensis and S. globosa. The environmental species, such as S. pallida, rarely infect humans.

Global Incidence

Sporotrichosis is found worldwide, particularly in tropical regions. It is common in individuals with occupations leading to skin injuries from soil and plants, such as florists and gardeners. Recent studies link cat ownership to an increased risk of sporotrichosis, as infected cats can transmit the disease through scratches or bites.

Symptoms and Diagnosis

Symptoms of sporotrichosis can take a few days to months to appear. The most common form includes cutaneous lesions, often appearing as papules or nodules that can ulcerate. Diagnosis typically relies on isolating the fungus through laboratory culture.

Treatment Options

The standard treatment for sporotrichosis is itraconazole, an antifungal medication. Other medications like terbinafine and ketoconazole show some effectiveness, but itraconazole remains the primary choice.

Recent Trends in Thailand

Emerging Cases

Sporotrichosis is relatively rare in Thailand, but since 2018, hospitals have seen a rise in cases, particularly in Bangkok. This increase correlates with a rise in sporotrichosis cases observed in stray cats.

Study Overview

A study at Siriraj Hospital analyzed 49 patients diagnosed with cutaneous sporotrichosis from January 2018 to August 2022. Most patients were female, and the average age was around 58 years. Many patients had a history of cat exposure, often linked to scratches from infected cats.

Clinical Findings

The most common symptoms were lymphocutaneous lesions. Histopathological examinations showed granulomatous inflammation, but fungi were rarely found in tissues. Most patients improved over time, with around 50% achieving remission within six months.

Conclusion

Sporotrichosis is an emerging concern in Thailand, mainly linked to cat exposure. Clinicians must be aware of its symptoms and treatment options to effectively manage this infection and educate pet owners on preventing transmission. Early diagnosis and appropriate antifungal treatment are crucial for better patient outcomes.