Diseases / List of Fungal / Algal Diseases / Disease description:

Pneumocystosis in Lagomorphs, Ferrets and Great Apes

INFORMATION AVAILABLE

GENERAL INFORMATION

CLINICAL CHARACTERISTICS & PATHOLOGY

INVESTIGATION & DIAGNOSIS

TREATMENT & CONTROL

SUSCEPTIBILITY & TRANSMISSION

ENVIRONMENT & GEOGRAPHY

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General and References

Disease Summary

Pneumocystis carinii is a ubiquitous fungal organism which causes lung infections in humans and various laboratory animals. (B614.10.w10)
Lagomorphs Lung infection which has been seen occurring naturally in both rabbits and hares. (B614.10.w10)
Ferrets Usually an inapparent infection; clinical disease may occur with immunosuppression. (B627.17.w17, J213.6.w3)
Great Apes Respiratory infection usually of immunocompromised individuals, generally diagnosed at necropsy. (B644.2.w2)

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Alternative Names (Synonyms)

  • Pneumocystis carinii infection
  • Pneumocystis pneumonia.

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Disease Type

Fungal Infection

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Infectious/Non-Infectious Agent associated with the Disease

Pneumocystis carinii. (B614.10.w10, J505.28.w1)
  • Pneumocystic carinii is an atypical fungus. First described in the early 1900s, it was thought to be a protozoan until the 1990s. (J128.9.w4)
  • Ferrets have their own antigenically and genetically distinct strains of Pneumocystis carinii. (J213.6.w3)

Infective "Taxa"

Non-infective agents

--

Physical agents

-- Indirect / Secondary

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References

Disease Author

Nikki Fox BVSc MRCVS (V.w103); Dr Debra Bourne MA VetMB PhD MRCVS (V.w5)
Click image for main Reference Section

Referees

Brigitte Reusch BVet Med (Hons) CertZooMed MRCVS (V.w127)

Major References / Reviews

Code and Title List

J128.9.w4

Rabbits:
B614
.10.w10
J505.28.w1

Ferrets:
B627.17.w17
J127
.68.w1, J213.6.w3

Great Apes:
B644.2.w2

Other References

Code and Title List

J1.42.w5, J33.38.w1, J93.35.w2

Ferrets: B602.7.w7

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Clinical Characteristics and Pathology

Detailed Clinical and Pathological Characteristics

General Pneumocystosis usually only causes lesions in the lungs. (B614.10.w10)

Clinical Characteristics

--
Lagomorphs In rabbits:
  • Pneumocystosis is often an inapparent infection in rabbits. (B614.10.w10)
  • In one study, cortisone treatment given to infected rabbits did not lead to clinical signs of pneumocystosis. (B614.10.w10)
  • Pneumonia has been reported in heavily parasitised weanling rabbits; most recovered in two to three weeks. (B614.10.w10)
  • Clinical pathology
    • Increased serum lactate dehydrogenase and triglyceride levels have been reported in naturally occurring infections of rabbits. (B614.10.w10)

In Lepus timidus - Mountain hare in Finland: (J1.42.w5)

  • Low body weight and poor body condition. (J1.42.w5)
Ferrets
  • Respiratory signs. (J213.6.w3)
  • No relevant clinical signs in ferrets with experimental Pneumocystis carinii pneumonia. After 9 - 10 weeks of immunosuppressive corticosteroids, there was no weight loss and "all animals appeared healthy except for a mild coat roughing." (J127.68.w1)
Great Apes In Pan troglodytes - Chimpanzees:
  • Pyrexia, anorexia, cyanosis, pneumonia. (B644.2.w2)
    • Marked leucocytosis probably due to the concurrent erythrolaukaemia. (B644.2.w2)
    • Radiography: extensive lung lobe infiltrates. (B644.2.w2)

Incubation

--
Lagomorphs --
Ferrets Lesions were observed after nine to ten weeks of immunosuppressive treatment. (B627.17,w17)
Great Apes --

Mortality / Morbidity

--
Lagomorphs Pneumocystosis is often an inapparent infection in rabbits. (B614.10.w10)
Ferrets Usually inapparent in ferrets. Clinical disease may occur with immunosuppression. (B627.17.w17, J213.6.w3)
Great Apes Fatal in Pan troglodytes - Chimpanzees. (B644.2.w2)

Pathology

In humans and animals, pneumocystosis lesions are usually only found in the lungs. However, in humans, lesions have also been occasionally described in the liver, spleen, bone marrow and lymph nodes. (B614.10.w10)
Lagomorphs In Oryctolagus cuniculus domesticus - Domestic European rabbit with naturally occurring pneumocystosis:
  • pneumonitis;
  • vascular congestion;
  • oedema;
  • infiltration of the alveolar walls with macrophages and eosinophils. 

(B614.10.w10)

In Lepus europaeus - Brown hare
  • "Diffuse desquamative alveolitis with hyperplasia of some areas of alveolar epithelium". (B614.10.w10)
In Lepus timidus - Mountain hare in Finland: (J1.42.w5)
  • General: poor body condition, low body weight. (J1.42.w5)
  • Pulmonary: Pneumocystis  sp. cysts in the lungs, particularly the middle parts of the lobes, associated with inflammatory cells. (J1.42.w5)
Ferrets Gross
  • Pulmonary: in experimental ferrets following immunosuppressive therapy, the lungs appeared grossly normal.
  • Hepatic: the liver was yellow-tan in colour. (J127.68.w1)
  • No other abnormalities were visible.

Histopathology

  • Interstitial pneumonitis with focal infiltration of mononuclear cells as well as focally distributed cysts and trophozoites. (B627.17.w17)
  • Pulmonary: In ferrets following 9 -10 weeks immunosuppresive treatment: (J127.68.w1)
    • "Interstitial pneumonitis and alveolitis, with an intra-septal and intra-alveolar infiltrate of mononuclear cells." Widespread, patchily distributed or focal accumulations of Pneumocystis cairinii cysts visible with Gomori's methenamine silver nitrate stain. The inflammatory response was considered low considering the numbers of Pneumocystis carinii present, and few polymorphonuclear leucocytes were found. (J127.68.w1)
    • On electron microscopy, large numbers of cysts and trophozoites were visible. (J127.68.w1)
  • Liver: fatty vacuoles in hepatocytes.
  • Spleen: variable lymphocyte depletion and, in the red pulp, extramedullary haematopoiesis. (J127.68.w1)
Great Apes In Pan troglodytes - Chimpanzees

Gross pathology

  • Respiratory: pulmonary consolidation, diffuse or multifocal. Subpleural puperic haemorrhages. (B644.2.w2)
    • Pulmonary oedema, emphysema and pneumonia also reported. (B644.2.w2)

Histopathology

  • Respiratory: Interstitial penumonia, extensive, mainly mononuclear cell infiltrate. (B644.2.w2)
    • Organisms stained poorly on haematoxylin and eosin sections, but Gomori methenamine silver or periodic acid-Schiff stains showed cystic Pneumocystis organisms: dark brown/black with silver stain, 4-6 micrometer diameter round, ovoid or cup-shaped cysts, in a honeycomb matrix. (B644.2.w2)

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Human Health Considerations

  • Potential zoonosis: "It has been suggested that naturally infected animals in a human environment may serve as a reservoir of the disease". (B614.10.w10)
    • However, data from the wild and from experiments indicates that "cross-species transmission is unlikely, or at least will not cause persistent infection." (J505.28.w1)
  • This is an important infection in the immunocompromised, particularly AIDS patients, but also e.g. transplant recipients. (J93.35.w2, J505.28.w1)
  • Clinical findings in humans:
    • "In humans, pneumocystosis is associated with prematurity and early infancy, or with diseases and clinical therapy that depress the immunologic mechanism". (B614.10.w10)
    • Approximately 75 % of human patients with AIDS develop pneumonitis due to Pneumocystosis carinii. [1991] (B614.10.w10)
Clinical findings in humans:
  • "In humans, pneumocystosis is associated with prematurity and early infancy, or with diseases and clinical therapy that depress the immunologic mechanism". (B614.10.w10)
  • Approximately 75% of human patients with AIDS develop pneumonitis due to Pneumocystosis carinii. [1991] (B614.10.w10)

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Susceptibility / Transmission

General information on Susceptibility / Transmission

Susceptibility 
  • Clinical disease and pulmonary lesions associated with infection are seen most often in young or debilitated animals. (B614.10.w10)Experimentally, susceptibility is increased by immunosuppression. (J505.28.w1)
Transmission
  • Horizontal transmission via aerosols (airborne transmission) occurs, as shown in infections of laboratory rodents. (B614.10.w10, (J93.35.w2)
  • In utero transmission has been reported to occur in humans. (B614.10.w10)
Lagomorphs
Susceptibility 
  • Young or debilitated animals are most susceptible to this disease. (B614.10.w10)
  • In Lepus timidus - Mountain hare in Finland, infection was seen in both sexes, in young hares only. (J1.42.w5)
  • In a study of Lepus europaeus - Brown hare in the Netherlands, infection was found mainly in debilitated adults and in young hares with coccidiosis. (J505.28.w1)
  • In one study, cortisone treatment given to infected rabbits did not lead to clinical signs of pneumocystosis. (B614.10.w10)
Transmission
Ferrets
  • Ferrets may carry Pneumocystis carinii commonly as a commensal organism, but it does not usually cause disease. 
  • Clinical disease may occur in immunosuppressed ferrets. (B627.17.w17, J213.6.w3)
    • Ferrets may be relatively susceptible to development of Pneumocistis carinii pneumonia following treatment with corticosteroids. (B627.17.w17)
Great Apes
  • Non-human primates with general debility following recent importation, bacterial infection (experimental or natural), neoplasia orimmun deficiancy associated with retroviral infections have developed pneumocystosis. (B644.2.w2)

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Disease has been reported in either the wild or in captivity in:

Lagomorphs
Ferrets
  • Infection is not uncommon in ferrets, but disease has only been reported with immunosuppression. (B627.17.w17, J213.6.w3)

Great Apes

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

Lagomorphs (Lagomorpha - Lagomorphs (Order))

(List does not contain all other species groups affected by this disease)

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Disease has been specifically reported in Free-ranging populations of:

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

Lagomorphs (Lagomorpha - Lagomorphs (Order))

(List does not contain all other species groups affected by this disease)

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Environment/Geography

General Information on Environmental Factors/Events and Seasonality

  • --

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Regions / Countries where the Infectious Agent or Disease has been recorded

  • Pneumocystis carinii is an ubiquitous organism. (B614.10.w10)

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Regions / Countries where the Infectious Agent or Disease has been recorded in Free-ranging populations

  • --

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General Investigation / Diagnosis

General Information on Investigation / Diagnosis

  • Detection of the organism on bronchiolar or tracheal lavage. (J213.6.w3)
  • Polymerase chain reaction (PCR) techniques have been used to detect Pneumocystis carinii in human sputum and bronchoalveolar lavage samples. (B614.10.w10)
Lagomorphs
  • Diagnosis of this disease is based on the demonstration of Pneumocystis carinii organisms in tissue sections or lung smears using cytochemical staining. (B614.10.w10)
Ferrets
  • Clinical and radiographical signs of respiratory disease in an immunosuppressed ferret (on long-term steroid therapy, or an individual with hyperadrenocorticism and high blood cortisol levels. (B627.17.w17, J213.6.w3)
Great Apes
  • Consider in immunocompromised individuals with signs of pulmonary disease, such as dyspnoea. (B644.2.w2)
Related Techniques
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Similar Diseases (Differential Diagnosis)

--
Lagomorphs --
Ferrets --
Great Apes --

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Treatment and Control

Specific Medical Treatment

In rats: sulfadoxine (Sulphonamides) plus pyremethamine, pentamidine, and trimethoprim and sulfamethoxazole (Sulphonamides) have proved effective in the treatment of this disease. These drugs have also been used in humans. (B614.10.w10)
Lagomorphs
  • The effectiveness in rabbits of the drugs listed above are not known. (B614.10.w10)
Ferrets
Great Apes
  • In humans, Trimethoprim-sulfamethoxazole (Sulphonamides), Dapsone or aerosolized pentamidine have been used successfully. Treatment of one chimpanzee with intravenous pentamidine isethionate, 4 mg/kg for 14 days produced slight clinical improvement. (B644.2.w2)
Related Techniques

 

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General Nursing and Surgical Techniques

--
Lagomorphs --
Ferrets --
Great Apes Supplemental oxygen may provide temporary clinical improvement. (B644.2.w2)
Related Techniques
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Preventative Measures

Vaccination --
Lagomorphs --
Ferrets --
Great Apes  
Prophylactic Treatment

--

Lagomorphs --
Ferrets --
Great Apes
  • In humans, trimethoprime-sulfamethoxazole, dapsone or aerosolized pentamidine have been used successfully for prophylaxis. (B644.2.w2)
Related Techniques
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Environmental and Population Control Measures

General Environment Changes, Cleaning and Disinfection --

Lagomorphs

--
Ferrets --
Great Apes  
Population Control Measures --
Lagomorphs --
Ferrets --
Great Apes  
Isolation, Quarantine and Screening --
Lagomorphs --
Ferrets --
Great Apes  
Related Techniques
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