CLOSTRIDIUM PERFRINGENS INFECTION IN A MIXED PSITTACINE
COLLECTION
Frank Enders, DVM; Miguel Carases, DVM; Susan L. Clubb, DVM; and Prof. Dr. med. vet. Dr. habil. Helga Gerlach
Abstract :
C lostridium perfringens was associated with acute morbidity and mortality in a mixed psittacine collection. In the first outbreak five birds died, three of them without any previous clinical signs.
About one year later, a second outbreak oc-curred in which fifteen birds died. Most of these birds were found dead again with no previous clinical signs. All birds showed severe necrotic enteritis on post mortem examination. Treatment with antibiotics (clindamycin) was successful in three
Moluccan cockatoos ( Cacatua moluccensis ). Environmental and hygienic problems may have contributed to the development of the disease.
Key words : Clostridium perfringens , enteritis, psittacine birds, and avian flock.
Introduction
The Clostridia are anaerobic, spore-forming bacteria that are ubiquitous and can survive in soil and feces for many years. They are considered minimally conta-gious, but epornitics can occur when a group of individuals is exposed to the same source of infection. In raptors and birds with well developed ceca (e.g. galliformes, anseriformes and struthioniformes) the Clostridia are considered to be part of the autochthonous intestinal flora and disease outbreaks are generally related to stressors or other diseases, or reduced intestinal peristalsis.1,2
Clostridium perfringens infections are well recognized in domestic poultry as-sociated with necrotic or ulcerative enteritis or gangrenous dermatitis. Adverse cir-cumstances allow the bacteria to colonize the intestines, producing exotoxins that lead to clinical signs, lesions or death. The clinical signs include depression, dehy-dration, diarrhea, hematochezia, polydipsia, emaciation or sudden mortality. Such a disease usually occurs in young birds whereas adults are considered more resistant.1-3
In psittacines Clostridium perfringens is not considered to be part of the autochthonous intestinal flora. Clinical cases or flock outbreaks have been reported occasionally in the following species:
Quaker parakeet ( Myiopsitta monachus ), severe macaw ( Ara severa ), and green-winged macaw
( Ara chloroptera )4 , a group of great-billed parrots ( Tanygnathus megalorhynchus )5, and in various lorikeets. 6.8 The lesions described were similar to those seen in poultry. From a
Moluccan cockatoo ( Cacatua moluccensis ) with chronic colitis. Clostridium tertium was isolated.9
This report describes two outbreaks of enteral disease associated with Clostridium perfringens infection in a mixed psittacine collection. A very high mortality rate was observed among the affected individuals. Possible sources of the infection, species susceptibility and preventive measures were evaluated.
Case Report
In May 1996 five juvenile (3-9 months old) Conures ( Pyrrhura cruentata, Pyr-rhura perlata and three Pyrrhura sordida ), which were housed in the same cage died within ten days. Three of them died with no previous signs. Two others died after one or two days of depression, anorexia and vomiting after tube feeding. They did not respond to initial antibiotic therapy with
Enrofloxacin (Baytril, Bayer, Leverkusen, Germany) (15 mg/kg IM q24h).

Necropsy revealed in most of the birds a slightly reduced body condition and swollen abdomen.
The intestines were discolored appearing almost black. Fibrous adhesions joined adjoining intestinal loops into a hard palpable mass of tissue. Palpation of the intestines revealed a hard rubber-like texture of the contents of the upper jejunum, which appeared to consist of coagulated blood. The lumen was occluded with this caseous black material. The intestinal mucosa and muscularis showed necrotic areas and ulcers. The more distal parts of the jejunum contained semi-liquid gray-brown ingesta with a typical malodor. Spleens were pale and slightly to very enlarged. Livers appeared normal. Some cases showed proventriculitis and ventriculitis as well as ascites and peritonitis.
Samples of the ingesta stained by Gram stain showed a large number of budding yeasts as well as numerous gram-positive rods containing spores. Bacteriology resulted in the presence of profuse Clostridium perfringens type B.
Histopathology revealed characteristic necrotic enteritis involving mucosa, submucosa and muscularis with masses of bacteria, peritonitis, purulent hepatitis, ventriculitis with mononuclear infiltrations.
No similar cases were recorded in the collection in the past and the outbreak stopped following two more mortalities in adjacent cages within the next three months ( Pyrrhura p. lepida and Ara n. cumanensis , both juvenile birds). Again Clostridium perfringens was isolated from the intestine.
A second outbreak occurred between February and July of 1997. Fifteen birds died in this outbreak. They were either juvenile Conures ( Pyrrhura spp .) or adult Lories ( Eos spp., Lorius spp., and Chalcopsitta spp.
) with just three exceptions: an adult Amazona finschii with severe hemochromatosis and two juvenile Cacatua moluccensis with concurrent myeloblastosis. All of the Pyrrhuras, the Cockatoos, the Amazon and most of the Lories were found dead with no previous clinical signs observed. Two of the Lories survived for up to one week.
Post mortem finding in the Pyrrhuras were similar to those in the previous cases. Hepatomegaly and hepatic necrosis were observed in some birds. All of the lories showed peritonitis and distended, fluid filled and partly necrotic or ulcerated intestinal loops filled with malodorous ingesta. The liver was enlarged in birds with ulcers or ascites. The spleen was either normal or pale and slightly enlarged. In two cases the kidneys were pale. The body condition was normal with just one exception. The Amazon as well as the Moluccans showed reduced to very reduced body condition, very dilated intestinal loops filled with gray-black, liquid, foul-smelling ingesta and with diphtheritic necrosis of the wall. Liver and spleen were enlarged.
Histopathology revealed necrotic purulent enteritis with ulceration of the mu-cosa, peritonitis, purulent hepatitis with hemochromatosis and necrosis of renal tubules.
The only birds that showed severe symptoms of clostridial enteritis and survived the disease were three Moluccan cockatoos (Cacatua moluccensis) with reduced body condition, depression, anorexia, gray-watery diarrhea with malodorous feces. CBC revealed a profound anemia (PCV of 10%, reference range 38-48%10 ) and hypoproteinemia (plasma protein of 1.0 g/dl, reference range 3.0-5.0 g/dl10 ). Treatment was initiated with claforan (Primafen, Hoechst Farma, Spain)
(100 mg/kg SC q8h), Vitamin K (Konakion, Spain) ( 1 mg/kg IM q24h), lactated Ringer's solution (10 ml/kg SC q8h) and dextrose 5% (10 ml/kg SC q8h) combined with clindamycin
(Dalacin, Upjohn Farmoquimica, Spain) (100 mg/kg PO q24h) and nystatine (Mycostatin,
Squibb Pharma, Spain) (300,000 IU PO q12h). For nutritional support birds were gavaged with a commercial hand rearing formula (Pretty Bird 19/12, Pretty Bird, USA) (50 ml/kg PO q8h). All

the Moluccan cockatoos responded very well and dramatic changes in the overall condition were seen within the first 2-3 days of treatment. The frequency of treatment was reduced but therapy was continued for 1-2 weeks. After this time the blood parameters were within published reference ranges and the body condition was normal. Several partners of dead Lories and
Pyrrhuras that were treated prophylactically with clindamycin orally as per above, showed no clinical signs or side effects during the treatment period, however some of the Pyrrhuras died five months later during the second outbreak.
As the mortalities originated in different parts of the collection and different keepers managed the birds, food supplies and kitchen hygiene were evaluated. The kitchen floor drain was found to be connected to the septic system. All fittings and equipment were removed, the drain was sealed and the building cleaned and disinfected with gaseous formalin for 24 hours. Anaerobic bacterial cultures revealed clostridia from the Lory food and those vegetables that contained soil
(carrots, beets). Sources for vegetable were re-evaluated and only precleaned vegetables were purchased for feeding birds.
Traffic flow into the kitchen was evaluated. Traffic flow in front of and into the kitchen was restricted. Personnel having contact with untreated soil (such as gardeners) were not allowed to be near the kitchen. The only breeding center that was temporary moved on a soil surface was closed. A macaque ( Macaca mulatta ) died of tetanus in this area two years prior to this outbreak.
Aviaries of infected birds were emptied and flamed, all-organic material (perches/ ropes/ nestboxes) were flamed or discarded. No more deaths occurred in the next year.
Discussion
Clostridium perfringens has been associated in psittacines with severe necrotic enteritis.
Epornitics are rarely reported, but enteric infections without previous clinical signs and with high mortality have been reported in many species.1-8
Inadequate hygiene may contribute to colonization, as the bacterium is widely distributed and highly resistant in soil. Climatic factors may be contributory as clostridia appear to be more prevalent in the environment in the Spring and early Summer. Ingestion of a large number of spores or exotoxins combined with a reduced gastrointestinal motility may be necessary to develop the disease.1,2 Under given circumstances (e.g. the use of uncleaned vegetables, contact with soil and uncontrolled traffic flow in food preparation rooms) susceptible species of psittacines, especially ones that feed heavily on vegetables or on the ground, can develop fatal necrotic-hemorrhagic enteritis and can die within hours with no previous clinical signs. It is interesting to note that all of the clostridia isolated in these outbreaks were of the rarely reported type B instead of the more frequently described type A.1
C. perfringens type B is frequently described in small ruminants and in foals. In contrast to type
A, which produces only a-toxin, type B is capable of producing three major toxins (a-, b-, and -etoxins). While a- toxin is a lethal, necrotizing-hemolysing lecithinase, which occurs in all perfringes-types, are b- and e-toxin lethal and necro-tising.12 Although the capability of the various strains varies to produce similar amounts of major exotoxins, type B is more likely to be deadly than type A. This may explain the failure of treatment and the late deaths of the pyrrhuras. But as C. perfringens is not likely to sporulate within the organism it is to speculate that other Clostridia spp. were contributing to the disease process.
In evaluation of an outbreak special attention should be paid to food preparation, kitchen hygiene and areas with soil on the floor. Prophylactic treatment of partners should be considered. If the infection is diagnosed early, treatment or prophylaxis in the group is very effective as long as

normal gut transit is not affected. Antibiotic treatment is best achieved with clindamycine or metronidazole.11
In this outbreak a species predisposition was suspected, as clinical disease occurred just in a few genera dispite having 61 genera of psittacine birds in the collection. Food preference in these genera could have an influence on this pattern as food was suspected to be primary source of the pathogen. The only Cockatoo species involved in the outbreak was Cacatua moluccensis . These birds seemed to be more resistant and developed a chronic disease that responded well to the appropriate treatment.
Acknowledgments :
We thank Andrew Greenwood, BVSc, MBiol, MRCVS for comments on an earlier version of the manuscript.
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