Nosema disease

Definition

A contagious infection of insects, most notably adult honey bees (Apis mellifera) and silkworms (Bombyx mori), caused by microsporidian parasites of the genus Nosema. The pathogen invades the midgut epithelium, impairing digestion and nutrient absorption; in honey bees, the resulting condition is often called nosemosis or historically 'bee dysentery' when associated with diarrhea-like symptoms. Nosema apis and N. ceranae are the principal agents in bees, with the latter having displaced the former in many regions and linked to colony mortality. Transmission occurs via fecal-oral contamination of food, water, and comb. Diagnosis relies on microscopic detection of spores or molecular methods. The disease exemplifies how microsporidian infections can regulate host populations and influence pollinator health.

Etymology

From the genus name Nosema (Greek nōsēma, 'disease, sickness'), the type genus of microsporidian parasites, + 'disease'.

Example

Beekeepers monitor Nosema disease in spring by sampling bees and examining midgut smears for oval spores, as heavy infections reduce longevity and foraging efficiency, sometimes leading to colony failure if combined with other stressors.

Synonyms

• nosemosis
• microsporidiosis (broader, any microsporidian infection)
• bee dysentery (historical, symptom-based)

Related Terms

• Microsporidia
• Nosema apis
• Nosema ceranae
• Midgut
• epithelium
• spore
• pollinator decline
• colony collapse disorder
• silkworm disease
• entomopathogen

Usage Notes

Often used interchangeably with 'nosemosis' in apiculture literature, though 'nosemosis' technically denotes the pathological condition while 'Nosema disease' emphasizes the infectious agent. The term is usually uncountable; when distinguishing multiple etiological forms (e.g., Nosema apis vs. N. ceranae), specialists may write 'Nosema diseases' in the plural. Not to be confused with nosematosis, a rare variant spelling, or with Nosema as the genus name alone.