**Core Concept**
Systemic fungal infections are caused by fungi that have invaded the bloodstream and spread to various organs. These infections can be life-threatening and require prompt treatment. The most common systemic fungal infections include candidiasis, aspergillosis, histoplasmosis, and cryptococcosis.

**Why the Correct Answer is Right**
Systemic fungal infections can be caused by various fungi, including yeasts and molds. Candida species, such as Candida albicans, are common causes of systemic candidiasis. Aspergillus species, such as Aspergillus fumigatus, can cause aspergillosis, particularly in immunocompromised individuals. Histoplasma capsulatum causes histoplasmosis, which can be severe in individuals with weakened immune systems. Cryptococcus neoformans causes cryptococcosis, particularly in HIV-infected individuals.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is a common cause of systemic fungal infections.
**Option B:** This option is incorrect because it is a rare cause of systemic fungal infections.
**Option D:** This option is incorrect because it is a type of parasitic infection, not a fungal infection.

**Clinical Pearl / High-Yield Fact**
Fungal infections can be difficult to diagnose, but certain risk factors, such as immunocompromised status, organ transplantation, or prolonged antibiotic use, increase the likelihood of developing a systemic fungal infection.

**Correct Answer:** D.