Macrorhabdiosis

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An infectious disease in budgerigars , lovebirds , grass parakeets (Neophemas) and canaries is known as macrorhabdiosis (formerly also megabacteriosis ; English going-light syndrome ) . The causative agent is the yeast Macrorhabdus ornithogaster . Macrorhabdiosis is a chronic disease of the stomach with digestive disorders and mostly emaciation. The pathogen can also cause goiter infection.

Cause and development of the disease

The causative agent of the disease is Macrorhabdus ornithogaster , a gram- and PAS-positive rod-shaped fungus. The mushrooms are 40 µm long and 2 µm wide and do not form spores . The outdated name “megabacteriosis” should no longer be used as the disease is not caused by bacteria .

The transmission from infected parents to the young probably occurs through feeding. In adult budgies, the main routes of transmission are beaks and feeding, ingestion of infected faeces and infected drinking water. However, it is assumed that adult, healthy birds with an intact immune system do not or less often become ill. The risk of infection is therefore greater in young and very old birds. Birds that suffer from stressful situations are particularly susceptible . Stress is particularly evident in the following cases: change of diet, loss of the partner, adding a new partner, moulting or courtship .

The infection with Macrorhabdus ornithogaster leads to degenerative changes in the glandular stomach , which manifest themselves in the form of wall thickening of the glandular stomach, detachment of the koilin layer of the gizzard, formation of ulcers and an increase in the pH value .

The immune defense of the animal is reduced by the pathogen, whereby the local immune defense of the intestine is particularly affected. The result is often a secondary bacterial infection of the digestive system and, if the intestinal barrier is exceeded, the entire body.

It is known that some birds live with the pathogen and excrete it without any signs of disease.

clinic

The disease is unspecific and mostly chronic.

As a result of inadequate utilization of the ingested feed ( maldigestion ), the bird becomes emaciated with a normal or increased appetite ("going light syndrome") and ultimately death. In addition, however, cases are also described in which there was no underweight and the bird still died of macrorhabdiosis or a concomitant disease. In addition to emaciation, sick birds can choke out a gray glassy mucus and undigested grains. Occasionally blood appears in the feces, making them black in color and sandy in texture. Gagging and vomiting of grains as well as a deterioration in the general condition of the bird are also indications of Macrorhabdus ornithogaster.

In the patient population of the Clinic for Birds and Reptiles at the University of Leipzig , the pathogen could be detected in 48% of the animals admitted with gastrointestinal symptoms.

Diagnosis

Macrorhabdiosis can be detected by a microscopic examination of the feces. The Gram staining makes it easier to find the pathogen. A negative result is not a sure sign of exclusion, as the pathogen is not always excreted. Only about two thirds of the diseases are detected by a microscopic examination of the feces. A PCR of cloacal swabs offers greater diagnostic reliability. An X-ray can also give an indication of the disease, as the glandular stomach is enlarged in this case. However, the stomach of budgerigars cannot be easily visualized radiologically due to its small size. In birds that have died, the pathogens can be detected by dissecting the glandular stomach with a native specimen.

Therapy and prophylaxis

Since the disease has hardly been researched, the treatment methods are not yet fully developed.

Oral administration of neomycin and amphotericin B can be attempted for 14 days to 4 weeks until the symptoms disappear. The treatment is not without controversy, since on the one hand the administration triggers stress, which should be prevented as far as possible, and on the other hand the drugs have a toxic (poisonous) effect on the liver .

If macrorhabdiosis is detected, the entire bird population should be treated as far as possible, since even supposedly healthy birds can absorb and spread the pathogen.

Additional measures include adding gastric acidifying agents ( ascorbic acid , apple cider vinegar ) to the drinking water. Apple cider vinegar has an anti-fungal effect and has a positive effect on the intestinal flora. However, this agent should not be used too often, as bacteria in the healthy intestinal flora may also be killed. Various medicinal plants such as thyme , chamomile and sage are believed to have such an effect.

In addition, absolute hygiene must be observed. In particular, the infected feces should be removed from the cage, toys and landing areas on a daily basis because they contain the pathogens.

Sugar is to be avoided at all costs, because mushrooms feed on it. A switch to soft food and the removal of grit ensure mechanical protection of the stomach.

The prognosis is to be made carefully. In one study, only a third of the animals could be treated successfully. Relapses occurred in 17% of them. Apparently, amphotericin B does not completely eliminate the pathogen, but only reduces the number of yeasts in the intestine.

literature

  • K. Gabrisch, P. Zwart: Diseases of pets. 6th edition. Schlütersche, 2005, ISBN 3-89993-010-X .

Individual evidence

  1. ↑ a b c R. Püstow, ME Krautwald-Junghanns : The Incidence and Treatment Outcomes of Macrorhabdus ornithogaster Infection in Budgerigars (Melopsittacus undulatus) in a Veterinary Clinic. In: Journal of avian medicine and surgery. Volume 31, number 4, December 2017, pp. 344-350, doi : 10.1647 / 2016-181 , PMID 29327956 .
  2. ↑ PJ Sullivan, EC Ramsay, CB Greenacre, AC Cushing, X. Zhu, MP Jones: Comparison of Two Methods for Determining Prevalence of Macrorhabdus ornithogaster in a Flock of Captive Budgerigars (Melopsittacus undulatus). In: Journal of avian medicine and surgery. Volume 31, number 2, June 2017, pp. 128-131, doi : 10.1647 / 2016-213 , PMID 28644084 .
  3. ^ HR Baron et al .: Evidence of amphotericin B resistance in Macrorhabdus ornithogaster in Australian cage-birds. In: Medical mycology. [electronic publication before going to press] August 2018, doi : 10.1093 / mmy / myy062 , PMID 30085075 .

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