Megabacteriosis (Going Light Syndrome)

Megabacteriosis (Going Light Syndrome)
Budgie after medication

Megabacteriosis or going light syndrome can affect budgies of any age.

In adult birds, transmission of the so-called “megabacteria” occurs during partner feeding and in nestlings during feeding by the parents.

Unfortunately, even symptom-free budgies can be carriers of the pathogen.


The actual cause of this disease is relatively large rod-shaped germs, called megabacteria, in the glandular stomach. Although these germs were initially referred to as “megabacteria,” they are actually fungi (Macrorrhabudus ornithogaster).

The pathogens can colonize the stomach wall in small numbers for years without causing symptoms of any kind.

Stressful situations are apparently particularly responsible for the outbreak of the disease:

  • Moult
  • Malnutrition
  • Cage overcrowding
  • Loss of the partner bird

However, several factors (multifactorial events) must come together to cause a breakdown of the bird’s immune defenses and thus allow uncontrolled multiplication of the pathogen.


As the name going light syndrome already suggests, the affected animals show an increasing weight loss despite increased food intake and thus become lighter and lighter (“going light”).

Other symptoms include:

  • fluffed feathers
  • Diarrhoea
  • regurgitation and spitting out of grains
  • increased sand absorption
  • undigested grains in feces (advanced stage)

Megabacteriosis has a chronic course, with acute episodes alternating with periods of no symptoms, sometimes lasting weeks.

In the advanced stage, the affected budgies continue to emaciate until they finally die of debilitation.


In acute relapses, the drug “Ampho-Moronal” is administered for at least 5-6 days. The suspension is administered directly into the crop via a button cannula.

The active ingredient “amphotericin” acts only on the surface of the mucous membrane in the digestive tract and is not absorbed in the process (would otherwise be highly toxic). However, this cannot reach and kill the germs that are inside the mucosa of the stomach.

Since a complete elimination of the fungus (or the germs) is not possible, this is unfortunately a chronic disease, which means that the patients have to be treated again and again at varying intervals.

In addition, in acute attacks, symptomatic treatment with painkillers also brings relief from the symptoms.

To rebuild body weight, affected birds can be offered additional foxtail millet, which is usually readily accepted by patients.

In addition, they should be provided with a heat lamp (dark radiator) (even in symptom-free phases). This source of heat strengthens the immune system and prevents too rapid weight loss.

Other recommendations are:

  • whole food diet (without sugar, starch, etc.)
  • Fresh food containing vitamin A (e.g. chickweed)
  • sugar-free mineral & vitamin preparation (e.g. Primus Vital )
  • Avoidance of stress of any kind (e.g. conspecifics)
  • Doris Quinten: “Ziervogelkrankheiten”, p. 60f.
  • Megabakteriose (Körnerbude)