[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Other fungi of clinical interest](https://durgical.com/en/microbiology/groups/other-fungi-of-clinical-interest/) › Rhinosporidium seeberi

# Rhinosporidium seeberi

- Fungus
- For completeness

An aquatic microbe, long thought to be a fungus, that causes bleeding polyps in the nose or eye after bathing in ponds or rivers.

Updated Nov 13, 2026

Also called: rhinosporidiosis

## Quick facts

**Type**
Fungus · [Other fungi of clinical interest](https://durgical.com/en/microbiology/groups/other-fungi-of-clinical-interest/)

**Gram / shape**
In tissue

**Spread**
Contact of the nasal

**Causes**
Nasal rhinosporidiosis · Ocular rhinosporidiosis

**Treatment**
Complete surgical excision

On this page

- The basics Key points
- At a glance
- Morphology
- Transmission
- Life cycle
- In Colombia
- Memory aid
- What the colours mean

- Clinical Virulence factors
- Diseases it causes
- Clinical picture
- Diagnosis

- Treatment Treatment
- Prevention

- Study Test yourself

- Connections Connections

## Key points

- Unilateral, bleeding, strawberry-like nasal polyp in a person who bathes in ponds or rivers.
- Histology: giant sporangia with endospores.
- Cannot be cultured.
- Treated by surgery; drugs only as adjuncts.

## At a glance

**Shape**
In tissue: large thick-walled sporangia full of endospores

**Type**
Aquatic protist (Mesomycetozoea / Ichthyosporea), historically classified with the fungi

**Stain**
H&E, PAS, GMS and mucicarmine stain the sporangia

**Size**
Mature sporangia up to several hundred µm; endospores a few µm

## Morphology

- Huge round sporangia, visible even at low power, packed with thousands of endospores.
- Smaller immature stages (trophocytes) with a thick wall.
- It has never been grown on artificial culture media.

## Transmission

- Contact of the nasal or conjunctival mucosa with stagnant fresh water or soil, for example bathing in ponds and rivers.
- Minor trauma to the mucosa probably helps entry.
- Not spread from person to person.

**Reservoir:** Fresh water and possibly aquatic animals such as fish; also infects horses, dogs and cattle

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Life cycle

- Endospores from water or soil reach the nasal or conjunctival mucosa.
- Each endospore enlarges into a thick-walled trophocyte in the submucosa.
- The trophocyte grows into a large sporangium as its nucleus divides many times.
- The mature sporangium fills with thousands of endospores.
- It ruptures through a pore and releases endospores that spread locally and cause new polyps.

## Virulence factors

- Slow local growth that forms vascular, friable polyps.
- Endospores released into the tissue explain local spread and recurrence after surgery.
- Granulomatous and mixed inflammation around ruptured sporangia.

## Diseases it causes

- Nasal rhinosporidiosis: a pink to red, strawberry-like, friable polyp with unilateral obstruction and epistaxis.
- Ocular rhinosporidiosis: a fleshy polyp of the conjunctiva or lacrimal sac.
- Rarely skin, genital or disseminated lesions.

## Clinical picture

- Usually a young man from a rural area with unilateral nasal obstruction and bleeding.
- The polyp surface shows tiny white dots, which are the sporangia.
- It can look like an inverted papilloma or other benign nasal tumor.

## Diagnosis

- Histopathology of the excised polyp is the definitive test: sporangia with endospores.
- Smear of the lesion can show endospores.
- Culture does not work; PCR is a research tool.

## Treatment

Complete surgical excision, ideally endoscopic with cautery of the base, is the treatment. Drugs are not effective on their own; dapsone has been used after surgery to reduce recurrence. Recurrence occurs in a minority of patients.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

- [Dapsone](https://durgical.com/en/pharmacology/dapsone/)

## Prevention

- Avoiding bathing in stagnant ponds where cases occur.
- Careful complete excision to avoid seeding endospores.

## In Colombia

Colombia has reported cases: a 2012 report described a rural patient from Bolívar with a nasal polyp confirmed by histopathology.

## Memory aid

«A strawberry in the nose from the pond»: the white seeds of the strawberry are the sporangia, and only the scalpel removes it.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the typical presentation of rhinosporidiosis?

A unilateral, friable, bleeding nasal polyp with tiny white dots, in a person exposed to fresh water.

## How is Rhinosporidium seeberi confirmed?

By histopathology of the polyp, which shows large sporangia full of endospores; it cannot be cultured.

## What is the main treatment?

Complete surgical excision with cautery of the base; drugs such as dapsone are adjuncts only.

## Why was its classification controversial?

It looks like a fungus in tissue, but DNA studies placed it among aquatic protist parasites (Mesomycetozoea).

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/microbiology/rhinosporidium-seeberi/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

## Connections

## Related 2

- [Coccidioides immitis](https://durgical.com/en/microbiology/coccidioides-immitis/)
- [Mucorales (Rhizopus, Mucor)](https://durgical.com/en/microbiology/mucorales/)

[← Back to the group: Other fungi of clinical interest](https://durgical.com/en/microbiology/groups/other-fungi-of-clinical-interest/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Rhinosporidium seeberi: A Human Pathogen from a Novel Group of Aquatic Protistan Parasites](https://wwwnc.cdc.gov/eid/article/6/3/00-0307_article) (Emerging Infectious Diseases (CDC), 2000); [Diagnóstico diferencial de la rinosporidiosis: a propósito de un caso](https://revistas.udea.edu.co/index.php/iatreia/article/view/12415) (Iatreia (Universidad de Antioquia), 2012).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/rhinosporidium-seeberi/