Cryptococcosis in dogs: a retrospective study of 20 consecutive cases

Itraconazole in human medicine and veterinary practice

Diagnosis and management of fungal infections are challenging in both animals and humans, especially in immunologically weakened hosts. Due to its broad spectrum and safety profile when compared to other antifungals, itraconazole (ITZ) has been widely used in the treatment and prophylaxis of fungal infections, both in human and veterinary medicine. The dose and duration of management depend on factors such as the type of fungal pathogen, the site of infection, sensitivity to ITZ, chronic stages of the disease, the health status of the hosts, pharmacological interactions with other medications and the therapeutic protocol used. In veterinary practice, ITZ doses generally vary between 3 mg/kg and 50 mg/kg, once or twice a day. In humans, doses usually vary between 100 and 400 mg/day. As human and veterinary fungal infections are increasingly associated, and ITZ is one of the main medications used, this review addresses relevant aspects related to the use of this drug in both clinics, including case reports and different clinical aspects available in the literature.

Inhibition of Microbicidal Activity of Canine Macrophages DH82 Cell Line by Capsular Polysaccharides from Cryptococcus neoformans

Cryptococcus neoformans is a lethal fungus that primarily affects the respiratory system and the central nervous system. One of the main virulence factors is the capsule, constituted by the polysaccharides glucuronoxylomannan (GXM) and glucuronoxylomanogalactan (GXMGal). Polysaccharides are immunomodulators. One of the target cell populations for modulation are macrophages, which are part of the first line of defense and important for innate and adaptive immunity. It has been reported that macrophages can be modulated to act as a "Trojan horse," taking phagocytosed yeasts to strategic sites or having their machinery activation compromised. The scarcity of information on canine cryptococcosis led us to assess whether the purified capsular polysaccharides from C. neoformans would be able to modulate the microbicidal action of macrophages. In the present study, we observed that the capsular polysaccharides, GXM, GXMGal, or capsule total did not induce apoptosis in the DH82 macrophage cell line. However, it was possible to demonstrate that the phagocytic activity was decreased after treatment with polysaccharides. In addition, recovered yeasts from macrophages treated with polysaccharides after phagocytosis could be cultured, showing that their viability was not altered. The polysaccharides led to a reduction in ROS production and the mRNA expression of IL-12 and IL-6. We observed that GXMGal inhibits MHC class II expression and GXM reduces ERK phosphorylation. In contrast, GXMGal and GXM were able to increase the PPAR-γ expression. Furthermore, our data suggest that capsular polysaccharides can reduce the microbicidal activity of canine macrophages DH82.

A severe case of disseminated cryptococcosis in a young French bulldog living in South-East Queensland caused by Cryptococcus gattii VGII

BACKGROUND

Cryptococcus is one of the most common systemic mycosis worldwide, infecting young adults of the large to giant breed dogs. Infection is commonly acquired from the environment via the sinonasal cavity as the main portal of entry. It either remains there, or spreads to the central nervous system (CNS) and the eye (optic nerve and retina) by penetration of the cribriform plate, or haematogenously to other viscera. Lung involvement is uncommon in cats and dogs in contrast to human and equine patients. Whilst there is a wide genetic diversity amongst Cryptococcus neoformans and Cryptococcus gattii isolates along the West Coast and Northern parts of Australia, the molecular diversity of C. gatti is considered very low on the East Coast of Australia, with a huge preponderance of VGI cases. We report on a young small breed brachycephalic dog that presented with extreme gastrointestinal and respiratory signs, but no CNS involvement. It is the first reported case of C. gattii VGII genotype in a companion animal from Queensland.

CASE REPORT

A 9-month old female entire French Bulldog presented initially for diarrhoea. Clinical progression was accompanied by the development of respiratory signs, so the patient was referred to a 24 h care facility. Following hospitalisation, the patient became hypoxemic requiring mechanical ventilation. A bronchoalveolar lavage performed antemortem confirmed abundant Cryptococcal spp. Further culturing and genotyping identified the species as Cryptococcus gattii VGII. Post-mortem findings indicated gross gastrointestinal and mesenteric involvement, with possible dissemination to the local mesenteric lymph node and lungs.

CONCLUSION

This case describes a rare example of a Cryptococcus spp suspected of disseminating from the gastrointestinal tract to the lungs, without involvement of the CNS. The observation of this finding in a small brachycephalic breed is unusual, and the finding of genotype VGII on the East Coast of Queensland is extremely unusual as there is no prior travel history of the dog or owners. The presence of a miliary lung pattern with primary gastrointestinal disease in a small breed dog warrants adding cryptococcosis to the differential diagnosis.

Clinical features, outcomes, and long-term survival times of cats and dogs with central nervous system cryptococcosis in Australia: 50 cases (2000-2020)

OBJECTIVE

To describe the clinical findings and outcomes of Australian cats and dogs with CNS cryptococcosis.

ANIMALS

19 cats and 31 dogs with CNS cryptococcosis diagnosed between 2000 and 2020.

PROCEDURES

A case series and cohort study were performed using the same 50 animals. Both studies were multi-institutional and both retrospective and prospective. Disease features were compared between cats and dogs, and associations between putative risk factors and survival time (ST) were assessed.

RESULTS

Dogs were younger at initial presentation than cats and had lower latex cryptococcal antigen agglutination titers. Extraneurologic signs were common and frequently involved sinonasal and contiguous tissues. Neuroanatomic localization was predominantly forebrain, central vestibular (including cerebellum), multifocal, or diffuse. CSF analysis predominantly showed pleocytosis, with eosinophilic inflammation common in dogs. Seventy-eight percent (39/50) of patients received antifungal treatment. Median STs (from presentation) in treated patients were 1,678 days for cats and 679 days for dogs. Abnormal mentation at presentation (in dogs) and CSF collection (in cats) were associated with shorter STs. In treated dogs, those that received glucocorticoids prior to diagnosis, or single rather than multiple antifungal agents, had shorter STs.

CLINICAL RELEVANCE

The prognosis for feline and canine CNS cryptococcosis is guarded, yet long STs are possible with appropriate treatment. Presence of subtle upper respiratory tract signs may suggest cryptococcosis in patients with neurologic signs, while the absence of neurologic signs does not preclude CNS involvement.

An analysis of the population of Cryptococcus neoformans strains isolated from animals in Poland, in the years 2015-2019

Fungi belonging to the Cryptococcus neoformans/C. gattii species complex (CNGSC) are pathogens causing severe infections in humans and animals, that for humans may result in a mortality rate ranging up to 70%. The CNGSC is divided into eight major molecular types, that may differ in their virulence and susceptibility. In order to fully understand the epidemiology of cryptococcosis, it is important to study the world distribution and population structure of these pathogens. The present study is the first presenting a population of strains isolated in Poland and one of the few using a multi-species animal group as a source of the specimen. The pathogen was present in 2.375% of the tested animals. The URA5-RFLP and MALDI-TOF MS analyses have revealed that the population consisted exclusively of C. neoformans strains, with a predominance of major molecular type VNIV (C. neoformans var. neoformans). The MALDI-TOF MS was used to perform the CNGSC strains identification on both the species and sub-species level. Despite the fact that the animals providing the specimens were not treated with 5-fluorocytosine, around 10% of the tested population presented MIC values exceeding 64 mg/L, indicating the existence of the 5-fluorocytosine-resistant strains in the environment.

Cryptococcosis with ocular and central nervous system involvement in a 3-year-old dog

To date, cryptococcosis remains sporadic in Europe, and this is a case of canine cryptococcosis with ocular and CNS involvement in continental Europe with identification of the organism on cerebral spinal fluid (CSF) cytology and description of the clinical and MRI features, and outcome.

Cryptococcosis in the koala (Phascolarctos cinereus): pathogenesis and treatment in the context of two atypical cases

Disseminated cryptococcosis caused by Cryptococcus gattii (molecular type VGI) was diagnosed in an adult free-ranging female koala (Phascolarctos cinereus). Subclinical cryptococcosis was later diagnosed in this koala's joey. In the adult koala, a pathological fracture of the tibia was associated with the bone lysis of marked focal cryptococcal osteomyelitis. Limb-sparing orthopedic intervention, in the setting of disseminated cryptococcosis, was judged to have a poor prognosis, and the adult koala was euthanized. The joey was removed and hand-reared. Serological testing revealed persistent and increasing cryptococcal capsular antigenemia in the absence of clinical signs of disease and it was subsequently treated with oral fluconazole for approximately 16 months, rehabilitated and released into the wild. It was sighted 3 months post-release in a good state of health and again at 18 months post-release but was not recaptured on either occasion. This is the first published report of cryptococcal appendicular osteomyelitis in a koala. It is also the first report of concurrent disease in a dependent juvenile and the successful treatment of subclinical cryptococcosis to full resolution of the cryptococcal antigenemia in a free-ranging koala. This paper provides a discussion of cryptococcal osteomyelitis in animals, host-pathogen-environment interactions and treatment and monitoring protocols for cryptococcosis in koalas. Published reports describing the treatment of cryptococcosis in koalas are also collated and summarised.

An Overview of Sex Bias in C. neoformans Infections

Cryptococcosis, a fungal disease arising from the etiologic agent Cryptococcus neoformans, sickens a quarter of a million people annually, resulting in over 180,000 deaths. Interestingly, males are affected by cryptococcosis more frequently than females, a phenomenon observed for more than a half century. This disparity is seen in both HIV− (~3M:1F) and HIV⁺ (~8M:2F) populations of cryptococcal patients. In humans, male sex is considered a pre-disposing risk factor for cryptococcosis and males suffering from the disease have more severe symptoms and poorer outcomes. There are numerous observational, clinical and epidemiological studies documenting the male disadvantage in C. neoformans but with no further explanation of cause or mechanism. Despite being commonly acknowledged, little primary research has been conducted elucidating the reasons for these differences. The research that has been conducted, however, suggests sex hormones are a likely cause. Given that the sex difference is both prevalent and accepted by many researchers in the field, it is surprising that more is not known. This review highlights the data regarding differences in sexual dimorphism in C. neoformans infections and suggests future directions to close the research gap in this area.

Cryptococcus gattii infections

Understanding of the taxonomy and phylogeny of Cryptococcus gattii has been advanced by modern molecular techniques. C. gattii probably diverged from Cryptococcus neoformans between 16 million and 160 million years ago, depending on the dating methods applied, and maintains diversity by recombining in nature. South America is the likely source of the virulent C. gattii VGII molecular types that have emerged in North America. C. gattii shares major virulence determinants with C. neoformans, although genomic and transcriptomic studies revealed that despite similar genomes, the VGIIa and VGIIb subtypes employ very different transcriptional circuits and manifest differences in virulence phenotypes. Preliminary evidence suggests that C. gattii VGII causes severe lung disease and death without dissemination, whereas C. neoformans disseminates readily to the central nervous system (CNS) and causes death from meningoencephalitis. Overall, currently available data indicate that the C. gattii VGI, VGII, and VGIII molecular types more commonly affect nonimmunocompromised hosts, in contrast to VGIV. New, rapid, cheap diagnostic tests and imaging modalities are assisting early diagnosis and enabling better outcomes of cerebral cryptococcosis. Complications of CNS infection include increased intracranial pressure, severe neurological sequelae, and development of immune reconstitution syndrome, although the mortality rate is low. C. gattii VGII isolates may exhibit higher fluconazole MICs than other genotypes. Optimal therapeutic regimens are yet to be determined; in most cases, initial therapy with amphotericin B and 5-flucytosine is recommended.

Cryptococcosis as an emerging systemic mycosis in dogs

OBJECTIVE

To review the etiology, pathogenesis, and clinical presentations of canine cryptococcosis that are of relevance to veterinary emergency and critical care veterinarians. Diagnosis, treatment, and public health considerations of the disease will also be discussed.

ETIOLOGY

Cryptococcosis is a multisystemic disease of dogs, with a predilection for the CNS, caused by encapsulated yeast species of the genus Cryptococcus. The 2 main pathogenic species are Cryptococcus neoformans and Cryptococcus gattii (previously known as C. neoformans var. gattii). Cryptococcosis is an emerging disease in North America, with C. gattii gaining prominence as a cause of serious veterinary and human disease.

DIAGNOSIS

Definitive diagnosis is made by serologic (antigen) testing, culture, and identification of the organism using light microscopy. False negatives and false positives, while uncommon, can occur in dogs using commercially available antigen tests. Cytological examination demonstrates the organism in a majority of cases, although culture is more sensitive. Specific media are required to differentiate between C. neoformans and C. gattii.

THERAPY

The most commonly used antifungal drugs to treat canine cryptococcosis are azole antifungals and amphotericin B. Some strains of Cryptococcus are resistant to antifungal drugs, especially fluconazole. Cautious use of glucocorticoids in critically affected dogs with CNS presentations can improve outcome.

PROGNOSIS

Prognosis is variable and depends on the severity of disease, underlying host immunocompetence, and financial constraints of the owner. Altered mental status in dogs with CNS cryptococcosis is a negative prognostic indicator.

Feline cryptococcosis: impact of current research on clinical management

DISEASE SUMMARY: Cryptococcosis, principally caused by Cryptococcus neoformans and Cryptococcus gattii, is the most common systemic mycosis of cats worldwide. Cats may be infected following inhalation of spores from the environment, with the nasal cavity suspected as being the initial site of colonization and subsequent infection. Other sites of infection in cats are the skin, lungs, lymph nodes, central nervous system (CNS), eyes and, occasionally, periarticular connective tissue. Cryptococcosis can be diagnosed using serology (antigen testing), cytologic examination of smears, histopathology or culture. Treatment of localized disease is generally successful using azole antifungal drugs; however, cats with CNS involvement or disseminated disease require additional treatment with amphotericin B, with or without flucytosine. The prognosis is variable, depending on host and pathogen factors. Some cats require long-term (>1 year) treatment or indefinite therapy.

PATIENT GROUP

Cats of any breed, gender and age may be affected. Retroviral status does not appear to be a risk factor for developing cryptococcosis and indoor cats are not protected from disease.

GLOBAL IMPORTANCE

Feline cryptococcosis occurs worldwide, but is most frequently reported in Australia, western Canada and the western United States. Species and molecular type vary in different geographical regions and may affect clinical presentation and antifungal susceptibility patterns.

CLINICAL CHALLENGES

Serologic tests that detect cryptococcal antigen in serum are sensitive and specific, but false negatives can occur in cats with localized disease. Long-term drug therapy can be expensive and has the potential for toxicity. The extent to which the pathogenicity and antifungal susceptibility is affected by molecular type is currently under study.

EVIDENCE BASE

This review draws on recent literature relating to epidemiology, CNS involvement and advanced diagnostic imaging to update clinicians regarding research findings relevant to clinical practice.

Cryptococcosis in domestic animals in Western Australia: a retrospective study from 1995-2006

A retrospective study of cryptococcosis in domestic animals residing in Western Australia was conducted over an 11-year-period (from 1995 to 2006) by searching the data base of Murdoch University Veterinary Teaching hospital and the largest private clinical pathology laboratory in Perth. Cryptococcosis was identified in 155 animals: 72 cats, 57 dogs, 20 horses, three alpacas, two ferrets and a sheep. There was no seasonal trend apparent from the dates of diagnosis. Taking into account the commonness of accessions to Murdoch University, cats were five to six times more likely to develop this disease than dogs, and three times more likely than horses, while horses were almost twice as likely as dogs to become infected. Amongst the feline cohort, Ragdoll and Birman breeds were over-represented, while in dogs several pedigree breeds were similarly overrepresented. Dogs and horses tended to develop disease at an early age (one to five years), while cats were presented over a much wider range of ages. In cats and dogs the upper respiratory tract was the most common primary site of infection, while horses and alpacas tended to have lower respiratory involvement. The most striking finding of the study was the high frequency with which C. gattii was identified, with infections attributable to this species comprising 5/9 cats, 11/22 dogs, 9/9 horses and 1/1 alpaca, where appropriate testing was conducted. Preliminary molecular genotyping suggested that most of the C. gattii infections in domestic animals (9/9 cases) were of the VGII genotype. This contrasts the situation on the eastern seaboard of Australia, where disease attributable to C. gattii is less common and mainly due to the VGI genotype. C. gattii therefore appears to be an important cause of cryptococcosis in Western Australia.

Conventional and molecular diagnostic testing for the acute neurologic patient

OBJECTIVE

The aim of this review is to describe and evaluate both conventional and molecular diagnostic testing utilized in dogs and cats with acute neurologic diseases. Various types of polymerase chain reaction (PCR) are explored along with novel molecular diagnostic testing that ultimately may prove useful in the critical care setting.

DATA SOURCES

PUBMED was searched to obtain relevant references material using keywords: 'canine OR feline meningitis AND meningoencephalitis,''feline infectious peritonitis,''canine distemper,''canine OR feline AND toxoplasma,''canine neospora,''canine OR feline AND rickettsia,''granulomatous meningoencephalitis,''steroid responsive meningitis arteritis,''necrotizing encephalitis,''novel neurodiagnostics,''canine OR feline AND CNS borrelia,''canine OR feline AND CNS bartonella,''canine OR feline AND CNS fungal,''nested OR multiplex OR degenerate OR consensus OR CODEHOP AND PCR.' Research findings from the authors' laboratory and current veterinary textbooks also were utilized.

HUMAN DATA SYNTHESIS

Molecular diagnostic testing including conventional, real-time, and consensus and degenerate PCR and microarray analysis are utilized routinely for the antemortem diagnosis of infectious meningoencephalitis (ME) in humans. Recently, PCR using consensus degenerate hybrid primers (CODEHOP) has been used to identify and characterize a number of novel human viruses.

VETERINARY DATA SYNTHESIS

Molecular diagnostic testing such as conventional and real-time PCR aid in the diagnosis of several important central nervous system infectious agents including canine distemper virus, Toxoplasma gondii, Neospora caninum, rickettsial species, and others. Recently, broadly reactive consensus and degenerate PCR reactions have been applied to canine ME including assays for rickettsial organisms, Borrelia spp. and Bartonella spp., and various viral families.

CONCLUSIONS

In the acute neurologic patient, there are several key infectious diseases that can be pursued by a combination of conventional and molecular diagnostic testing. It is important that the clinician understands the utility, as well as the limitations, of the various neurodiagnostic tests that are available.

Emesis in dogs: a review

Emesis is a common presenting sign in small animal practice. It requires a rational approach to management that is based upon a sound understanding of pathophysiology combined with logical decision making. This review, which assesses the weight of available evidence, outlines the physiology of the vomiting reflex, causes of emesis, the consequences of emesis and the approach to clinical management of the vomiting dog. The applicability of diagnostic testing modalities and the merit of traditional approaches to management, such as dietary changes, are discussed. The role and usefulness of both traditional and novel anti-emetic drugs is examined, including in specific circumstances such as following cytotoxic drug treatment. The review also examines areas in which common clinical practice is not necessarily supported by objective evidence and, as such, highlights questions worthy of further clinical research.

Nasal cryptococcosis in two dogs in New Zealand

CASE HISTORY

Two young, large-breed female dogs were presented with an acute onset of sneezing and nasal discharge. One patient had concurrent epistaxis and facial deformity.

CLINICAL FINDINGS

Decreased airflow was noted through the left nostril in Case 1, while Case 2 showed facial deformity. Nasal radiographs from Case 1 showed a soft tissue opacity in the left nasal cavity and frontal sinus. Rhinoscopy revealed roughened, erythematous nasal turbinates in both patients, and a mass in the left caudal nasal cavity of Case 1. Cryptococcus spp. were demonstrated histopathologically on a nasal biopsy. Tissue culture and serum antigen titres were positive for Cryptococcus spp.

DIAGNOSIS

Chronic rhinitis secondary to Cryptococcus gattii infection in Case 1, and Cryptococcus neoformans infection in Case 2.

CLINICAL RELEVANCE

These are the first reported cases of Cryptococcus spp. rhinitis in dogs in New Zealand.

[Cryptococcosis and pets]

This paper is a review of cryptococcosis in domestic animals. Cryptococcosis is an uncommon mycosis in domestic animals and its occurrence is sporadic. The disease is caused by Cryptococcus neoformans, although Cryptococcus gattii has been also isolated from different animal species. Although cryptococcosis has been reported in several animal species, the most frequently affected domestic animal is the cat. The present paper deals with feline and canine cryptococcosis, its common clinical signs and the different clinical forms of the disease in these species. The diagnosis and treatment of cryptococcosis is also discussed. Diagnosis usually includes cytologic examination, capsular antigen detection and culture and identification of the Cryptococcus species. The management of criptococcosis will review the most common therapeutic agents and their role in therapy. Finally, we will address the situation of cryptococcosis in domestic animals in Spain and the role of cryptococcosis as a zoonotic disease and its public health importance.

Successful treatment of cryptococcal pneumonia in a pony mare

A 20-year-old Welsh Mountain Pony (212 kg) mare was initially presented for a chronic cough, fever, weight loss and low grade abdominal pain. She later developed dyspnoea, tachypnoea and exercise intolerance. The presence of multiple masses (up to 17 cm diameter) in the pulmonary parenchyma was established using lateral thoracic radiography and transthoracic ultrasonography. Encapsulated, budding yeasts were observed in smears made from transtracheal washings and needle aspirates of the pulmonary lesions. Cryptococcus gattii (synonym: Cryptococcus neoformans variety gattii; Cryptococcus bacillisporus) was cultured from the transtracheal washings and aspirates of the lung masses. The pony was successfully treated using daily intravenous infusions of amphotericin B (typically 0.5 mg/kg in 1 L 5% dextrose in water over 1 h, following premedication with 50 mg flunixin intravenously) over a 1 month period, until a cumulative dose of 3 g had been administered. Treatment was considered to be successful on the basis of progressive improvement in clinical signs, reduction in the size of pulmonary cryptococcomas, 48 kg weight gain and a reduction in the cryptococcal antigen titre from 4096 to 256, 1 year after cessation of treatment.

[Canine lymphadenitis caused by Cryptococcus neoformans. First case in Chile]

We report the first case of canine lymphoadenomegalia caused by Cryptococcus neoformans in Chile. Physical examination of a Rottweiler dog patient showed a generalized lymphoadenomegalia that affected the submandibular, superficial cervical and popliteus lymphatic nodules. Cryptococcus neoformans was isolated and identified from biopsies of the right submandibular nodule. After antifungal susceptibility, oral ketoconazole treatment was established for a period of six months showing clinical improvement. Two years post-treatment the patient showed no signs of the infection.

Long-term outcome of therapy for 59 cats and 11 dogs with cryptococcosis

OBJECTIVE

To determine the outcome of therapy in cats and dogs with naturally occurring cryptococcosis. Design Retrospective study of 59 cats and 11 dogs at the University Veterinary Centre Sydney from 1986 to 2004.

METHOD

Following detailed analysis of case notes potential associations between patient characteristics, cryptococcal species, retroviral status (cats), disease severity and type of therapy were examined in relation to duration and success of therapy. Treatment protocols based on amphotericin B, fluconazole and itraconazole were compared.

RESULTS

Seventy-six percent of feline patients were successfully treated. For cats, the presence of central nervous system disease was the only factor found to influence outcome. Cats with neurological involvement, disseminated disease or refractory disease treated with amphotericin B containing protocols did as well, on average, as cats with less severe disease treated with azole monotherapy. Amphotericin B was thus an effective agent for treating severe cases of cryptococcosis. The median cumulative dose of amphotericin B for cats cured at the first attempt was 16 mg/kg (range 7 to 23 mg/kg). The median duration of treatment required to effect a cure at first attempt was significantly shorter for fluconazole (4 months; range 1 to 8 months) than for itraconazole (9 months; range 3 to 24 months; P = 0. 0191; Mann Whitney U test). The success rate for treatment of canine cases was 55%. No factor appeared to influence disease outcome in dogs. Large cumulative doses of amphotericin B could be administered via the subcutaneous route in both species and generally with minimal nephrotoxicity. Recrudescence occurred in a significant proportion of animals, in some cases despite a reduction of serum latex cryptococcal antigen agglutination test to zero.

CONCLUSION

Although the prognosis of cryptococcosis should be described as guarded, a majority of the canine and especially feline patients can be expected to be cured, although treatment is protracted and expensive.

Evaluation of risk factors for Cryptococcus gattii infection in dogs and cats

OBJECTIVE

To determine risk factors associated with Cryptococcus gattii infection in dogs and cats residing on Vancouver Island in British Columbia, Canada.

DESIGN

Matched case-control study.

ANIMALS

20 dogs and 29 cats with C gattii infection and matched controls.

PROCEDURE

Dogs and cats with a confirmed or probable diagnosis of cryptococcosis resulting from infection with C gattii were enrolled by veterinarians, and owners completed a questionnaire designed to obtain information pertaining to potential risk factors for the disease. Owners of matched control animals were also interviewed. Odds ratios and 95% confidence intervals or paired t tests were calculated to determine significant associations.

RESULTS

Animals were enrolled during 2 noncontiguous periods in August 2001 to February 2002 (8 dogs and 9 cats enrolled) and May to December 2003 (12 dogs and 20 cats enrolled). Risk factors significantly associated with development of cryptococcosis included residing within 10 km of a logging site or other area of commercial soil disturbance, above-average level of activity of the animal, travelling of the animal on Vancouver Island, hunting by the animal, and owners hiking or visiting a botanic garden.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that dogs and cats that were active or that lived near a site of commercial environmental disturbance had a significantly increased risk of developing C gattii infection. Veterinarians should communicate these risks to owners in context because cryptococcosis was an uncommon disease in this population.

Sub-clinical infection and asymptomatic carriage of Cryptococcus gattii in dogs and cats during an outbreak of cryptococcosis

Since 1999, Cryptococcus gattii has emerged as an important pathogen of humans and animals in British Columbia, Canada. Nasal swabs and serum samples were collected from dogs and cats residing within the Coastal Douglas Fir biogeoclimatic zone on Vancouver Island, where clinical cases have been reported. Deep and superficial nasal fungal cultures of 280 dogs and 94 cats identified four (4.3%) cats and three (1.1%) dogs with C. gattii serotype B in their nasal cavity. Serum samples collected from 266 dogs and 84 cats identified six (7.1%) cats and two (0.8%) dogs with a positive cryptococcal antigen titer. Overall cats were 4.4 times more likely than dogs to be positive on one or both tests. Identification of sub-clinical infection and nasal colonization is an important step in the characterization of the outbreak of clinical cryptococcosis on Vancouver Island.

Retrospective study of feline and canine cryptococcosis in Australia from 1981 to 2001: 195 cases

A retrospective study of 155 cats and 40 dogs diagnosed with cryptococcosis between 1981 and 2001 was undertaken. Age, sex, breed, clinical findings, feline immunodeficiency virus and feline leukaemia virus status (in cats), species of Cryptococcus causing disease and region of domicile were recorded. Associations between variables were tested. Male and female cats were affected equally. Age ranged from 1 to 16 years, with a preponderance of cats aged between 2 and 3 years. Siamese, Himalayan and Ragdoll breeds were over-represented. Rural cats were more frequently infected with Cryptococcus gattii. Retroviral infection was not identified as a predisposing condition and was not correlated with either species of Cryptococcus or physical findings. Most cats had signs of nasal cavity infection, which was typically localised for a substantial period before invasion of adjacent structures or dissemination. Male and female dogs were affected equally. A marked preponderance of young, large breed dogs was noted. Border Collies, Boxers, Dalmatians, Dobermann Pinschers, Great Danes and German Shepherds were over-represented. Cryptococcus species involved was not affected by place of domicile. Although nasal cavity involvement was important, the canine cohort had a greater propensity to develop secondary central nervous system involvement and disseminated disease than feline cases. There were no clinical findings in either cats or dogs which could be reliably used to distinguish disease caused by Cryptococcus neoformans variety grubii from disease caused by Cryptococcus gattii. Both Cryptococcus species appear to be primary pathogens of cats and dogs, with the upper respiratory tract presumed to be the predominant primary site of inoculation in most but not all cases.

Clinicopathologic features of an unusual outbreak of cryptococcosis in dogs, cats, ferrets, and a bird: 38 cases (January to July 2003)

OBJECTIVE

To determine clinical and pathologic findings associated with an outbreak of cryptococcosis in an unusual geographic location (British Columbia, Canada).

DESIGN

Retrospective study.

ANIMALS

1 pink-fronted cockatoo, 2 ferrets, 20 cats, and 15 dogs.

PROCEDURE

A presumptive diagnosis of cryptococcosis was made on the basis of serologic, histopathologic, or cytologic findings, and a definitive diagnosis was made on the basis of culture or immunohistochemical staining.

RESULTS

No breed or sex predilections were detected in affected dogs or cats. Eleven cats had neurologic signs, 7 had skin lesions, and 5 had respiratory tract signs. None of 17 cats tested serologically for FeLV yielded positive results; 1 of 17 cats yielded positive results for FIV (western blot). Nine of 15 dogs had neurologic signs, 2 had periorbital swellings, and only 3 had respiratory tract signs initially. Microbiologic culture in 15 cases yielded 2 isolates of Cryptococcus neoformans var grubii (serotype A) and 13 isolates of C. neoformans var gattii (serotype B); all organisms were susceptible to amphotericin B and ketoconazole. Serologic testing had sensitivity of 92% and specificity of 98%.

CONCLUSIONS AND CLINICAL RELEVANCE

Serologic titers were beneficial in identifying infection in animals with nonspecific signs, but routine serum biochemical or hematologic parameters were of little value in diagnosis. Most animals had nonspecific CNS signs and represented a diagnostic challenge. Animals that travel to or live in this region and have nonspecific malaise or unusual neurologic signs should be evaluated for cryptococcosis.

Investigation in Central Italy of the possible association between Cryptococcus neoformans var. Gattii and Eucalyptus camaldulensis

The authors present a worldwide review of isolations of Cryptococcus neoformans, var. neoformans and C. neoformans var. gattii from animals and vegetation, referring in particular to the already well-known association of the former variety with Eucalyptus camaldulensis. They then review the Italian situation relative to this association and their studies carried out in Central Italy: in Latina (Lazio), Pisa, Viareggio and Lake Massaciuccoli (Tuscany). From the 256 E. camaldulensis trees examined C. neoformans var. gattii was not isolated. An E. camaldulensis tree situated in the nature reserve on Lake Massaciuccoli proved to be positive for C. neoformans var. neoformans. This variety was isolated from the leaves, flowers, bark and the debris at the foot of the tree, suggesting that it had colonized the entire tree and that it was capable of developing not only on its usual habitat (bird guano, soil rich with guano) but also on Eucalyptus trees. The identity of the isolates was confirmed by their genomic profiles obtained by random amplification polymorphic DNA (RAPD) with the primer (GACA)4. The presence of a single genotype indicates a sole source of contamination, perhaps brought by a bird coming from a contaminated environment.

Criptococose canina: relato de caso

Descreve-se, pela primeira vez no Brasil, um caso de criptococose canina com acometimento oftalmo e dermatopático, com diagnóstico intra-vitam, em animal da raça Pastor Alemão, fêmea, com 24 meses de vida, criado em São Paulo, em contacto com outros cinco cães assintomáticos, que havia se infectado pelo contato com dejetos de pombos (Columba livia). Evoluia há 90 dias, com quadro tegumentar e ósseo, sintomas e lesões características, sendo, ainda, detectada forma assintomática de coriorretinite, de início unilateral. O diagnóstico foi estabelecido pelos dados da anamnese, dos exames físico, dermatológico e complementares (radiográfico, cultivo micológico, histopatologia de pele) tendo-se evidenciado e isolado cepa de Criptococcus neoformans var. neoformans. Após nove meses de terapia com itraconazol (9mg/kg/SID/VO) houve involução total do quadro, sem qualquer efeito adverso à droga.

Cryptococcus neoformans var. gattii in the koala (Phascolarctos cinereus): a review of 43 cases of cryptococcosis

Details of 11 previously reported cases and 32 new cases of cryptococcosis in captive and wild koalas were analysed. Cryptococcus neoformans var. gattii accounted for all 29 cases in which varietal status was determined. No age or sex predisposition was observed. The respiratory tract was the primary focus of disease in 77% of cases. Although the lower respiratory tract was affected most commonly (60% of cases), 30% of cases had upper respiratory tract lesions and 14% had both. Dissemination was common, especially to the central nervous system (37% cases). Local extension to surrounding tissues was a feature of upper respiratory tract disease. Other tissues showing cryptococcal invasion included lymph nodes (19%), gastrointestinal tract (12%), kidneys (12%), spleen (9%) and skin (7%). Only three cases (7%) had no respiratory tract or central nervous system involvement, two cases of primary skin inoculation and one case of primary lymphadenopathy. Late presentation was a likely factor in the high proportion of cases with disseminated disease (40%). The proportion of koala cases with involvement of the central nervous system, lower respiratory tract and skin, parallels what has been reported for immunocompetent people. Cryptococcosis in the koala appears to be an excellent naturally occurring model for examination of the cryptococcal host-parasite relationship in all species.

Avian cryptococcosis

Clinical and laboratory findings in 15 unreported cases of avian cryptococcosis from Australia were collated and contrasted with 11 cases recorded in the literature. Cryptococcus species produced localized invasive disease of the upper respiratory tract of captive parrots living in Australia. This resulted in signs referable to mycotic rhinitis or to involvement of structures contiguous with the nasal cavity, such as the beak, sinuses, choana, retrobulbar space and palate. Parrots of widely differing ages were affected and of the seven birds for which sex was determinable, six were male. Cryptococcus bacillisporus (formerly C. neoformans var. gattii) accounted for four of five infections in which the species or variety was determinable, suggesting that exposure to eucalyptus material may be a predisposing factor. In these cases, Cryptococcus appeared to behave as a primary pathogen of immunocompetent hosts. One tissue specimen was available from an Australian racing pigeon with minimally invasive subcutaneous disease; immunohistology demonstrated a C. neoformans var. grubii (formerly C. neoformans var. neoformans serotype A) infection, presumably subsequent to traumatic inoculation of yeast cells into the subcutis. Two similar cases had been reported previously in pigeons domiciled in America. Data for parrots, one pigeon and other birds studied principally in America and Europe (and likely infected with C. neoformans) suggested a different pattern of disease, more suggestive of opportunistic infection of immunodeficient hosts. In this cohort of patients, the organism was not restricted to cool superficial sites such as the upper respiratory tract or subcutis. Instead, infections typically penetrated the lower respiratory tract or disseminated widely to a variety of internal organs. Finally, three captive North Island brown kiwis, one residing in Australia, the other two in New Zealand, died as a result of severe diffuse cryptococcal pneumonia (two cases) or widely disseminated disease (one case). C. bacillisporus strains were isolated from all three cases, as reported previously for another kiwi with disseminated disease in New Zealand.

Cryptococcal pyelonephritis in a dog

A 5-year-old castrated male Golden Retriever was evaluated for polyuria, polydipsia, and progressive regurgitation thought to be a result of bacterial pyelonephritis and megaesophagus. Bacteriologic culture of urine failed to yield clinically relevant growth, and results of a urine sediment examination were normal. With time, intention tremors and progressive neurologic dysfunction were also observed. At necropsy, a diagnosis of cryptococcal disease was confirmed histologically and immunohistochemically. Findings in the dog of this report were indicative of nephrogenic diabetes insipidus with polyuria and polydipsia caused by cryptococcal pyelonephritis. Neurologic manifestations of systemic cryptococcus infection included megaesophagus, esophageal hypomotility, and regurgitation attributed to localization of cryptococcal organisms in the brain stem in the region of the dorsal motor nucleus of the vagus nerve. To the authors' knowledge, this is the first report of polyuria secondary to cryptococcal pyelonephritis.

Cryptococcus neoformans in the koala (Phascolarctos cinereus): colonization by C n. var. gattii and investigation of environmental sources

This study is the one in a series looking at the relationship among Cryptococcus neoformans var. gattii, koalas and the environment. The koala was used as a natural biological sampler in an attempt to understand the dynamics of C. neoformans var. gattii in Australian environments. Evidence of asymptomatic nasal and skin colonization for extended periods by large numbers of C. n. var. gattii was obtained and geographical factors assessed. The key finding was the ability of koalas to amplify numbers of C. n. var. gattii in certain environments. Koalas were not found to be obligatory for the survival of the organism in all environments. Geographical factors alone could not explain differing rates of nasal and skin colonization in koalas in different environments. A strong association between healthy koalas and C. n. var. gattii was confirmed and C n. var. gattii was isolated from novel sources, including the turpentine gum tree (Syncarpia glomulifera), tallowwood (Eucalyptus microcorys) and flooded gum (E. grandis). It seems likely that as yet undiscovered environmental sources of C. n. var. gattii exist in eastern Australia. Further investigation of host, environmental and organism factors integral to the hostpathogen relationship will assist an understanding of the progression from colonization to tissue invasion and cryptococcosis in all species.

An immunohistochemical method that differentiates Cryptococcus neoformans varieties and serotypes in formalin-fixed paraffin-embedded tissues

An immunohistochemical method for determining the variety of Cryptococcus neoformans in formalin-fixed paraffin-embedded tissues was developed using mAbs 471, 302 and CRND8. The method was validated primarily using veterinary patients for which both formalin-fixed lesions and a cultured isolate were available. L-Canavanine glycine bromothymol blue (CGB) agar and the 'Crypto-Check' kit were used to determine the variety and serotype, respectively, of cultured isolates. Immunohistochemistry accurately predicted the C. neoformans variety in all tissue specimens. The CGB agar method of determining C. neoformans variety gave the same result as immunohistochemistry for 30/31 specimens. For the single discordant isolate, the serotype, random amplification of polymorphic DNA profile, microscopic and colony morphology all supported the immunohistochemical staining pattern in suggesting C. neoformans var. gattii; however, the CGB agar result was at variance. Of the C. neoformans var. neoformans cases, immunohistochemistry was congruent with variety for 13/13 cases and with serotyping for 10/13 cases. The three discordant cases were classified as having some serotype D reactivity by immunohistochemistry, but were considered to be serotype A using the Crypto-Check kit. This new method should prove a valuable epidemiological tool in studies of cryptococcosis, especially in the veterinary setting where archival tissue specimens may exist but corresponding mycological data is typically absent. The versatility of this method will expand in the future as other monoclonal antibodies with different specificities are developed.

Canine systemic fungal infections

The principal route of infection for the disseminated fungal diseases discussed in this article is inhalation. In some cases, direct wound contamination and ingestion may also have an important role in the pathogenesis of the disease, especially in histoplasmosis. Another common theme of these diseases is the response of the immune system. If the inoculum is small and the animal is not immunocompromised, the infection may be limited to the respiratory tract and may resolve with few or no clinical signs. Dogs are usually presented to the veterinarian when the fungus has disseminated throughout the body via the circulatory or lymphatic systems, thus causing clinical signs secondary to specific organ infection. Draining skin tracts and lymphadenopathy occur in several of the diseases. The ocular location that is frequently affected is the choroid, where the organisms cause cell-mediated chorioretinitis. Early detection of these changes is important for saving vision and for diagnosing the systemic nature of the disease. Treatment is often effective, especially early in the disease, although it is expensive and long-term, with many animals needing over a year of treatment. Sometimes the treatment must continue lifelong. Ocular disease may not respond to treatment even when respiratory and other organ system clinical signs are rapidly improving. This isolation of the eye is similar to that of the CNS and requires regular monitoring of ocular disease, especially in the fundus, to ensure that systemic drugs are penetrating into the eye. Once the disease progresses to the anterior segment, the ocular prognosis worsens. Better penetration of the blood-retinal and blood-aqueous barriers may be achieved with fluconazole when compared with the other antifungal drugs. Secondary inflammatory ocular disease must also be monitored and treated appropriately to prevent scarring, which may cause vision loss or glaucoma.

Successful treatment of invasive nasal cryptococcosis in a ferret

Invasive cryptococcal rhinitis due to Cryptococcus neoformans var gattii was diagnosed in a castrated, 5-year-old, albino ferret with subcutaneous swelling of the nasal bridge. The diagnosis was based on histology, needle aspirate cytology and positive culture on Sabouraud's dextrose agar and birdseed agar. The ferret was successfully treated using a long course of itraconazole (25 to 33 mg orally once daily with food) subsequent to surgical debulking of the lesion, using sequential cryptococcal antigen titre determinations to guide therapy.

Asymptomatic carriage of Cryptococcus neoformans in the nasal cavity of the koala (Phascolarctos cinereus)

Over a 22-month period, sequential nasal and skin swabs were obtained from 52 healthy captive koalas (Phascolarctos cinereus) from the Sydney region. Cryptococcus neoformans was isolated in 17 koalas from 64 of 262 (24%) nasal swabs and from nine of 262 (3%) skin swabs. Prevalence of nasal colonization varied seasonally from 12% (3/25) to 38% (10/26). Cryptococcus neoformans var. gattii alone was cultured from 37, var. neoformans alone from 22 and both varieties from five nasal swabs. Of 33 koalas sampled on three or more occasions, organisms were isolated persistently from six, occasionally from eight and never from 19. Two koalas were persistently and heavily (>/=100 colonies/plate) colonized by C. neoformans var. gattii and two with var. neoformans. Isolation of C. neoformans var. gattii from the skin was low grade and sporadic. No koalas from which C. neoformans was persistently isolated showed clinical signs of cryptococcosis and all except one had a negative latex cryptococcal antigen test, therefore the nasal cavity was presumed to be colonized by, rather than infected with, C. neoformans. Preliminary observations of koalas from Coffs Harbour indicated a much higher prevalence of colonization by C. neoformans, suggesting that environmental factors influenced the extent of carriage by C. neoformans.

A review of immunologic diseases of the dog

The following review is based on notes used in the teaching of clinical immunology to veterinary students. Immune diseases of the dog are placed into six different categories: (1) type I or allergic conditions; (2) type II or auto- and allo-antibody diseases; (3) type III or immune complex disorders; (4) type IV or cell-mediated immune diseases; (5) type V conditions or gammopathies; and (6) type VI or immunodeficiency disorders. Separate discussions of transplantation immunology and the use of drugs to regulate unwanted immune responses are also included.

Intra-abdominal cryptococcosis in two dogs

Intra-abdominal cryptococcosis was diagnosed in two young dogs. The first, an entire male border collie, was presented with vomiting. An abdominal mass detected during physical examination proved to be cryptococcal mesenteric lymphadenitis on exploratory laparotomy. The second dog, a female neutered giant schnauzer, was presented with neurological signs suggestive of encephalopathy. Intestinal cryptococcal granulomas were detected in an extensive diagnostic investigation which included abdominal ultrasonography. The gastrointestinal tract was considered the most likely portal of entry for cryptococcal organisms in both cases. Both dogs were treated using surgery and multiagent antifungal chemotherapy. The first case succumbed despite therapy, while the second dog was treated successfully as gauged by return to clinical normality and a substantial decline in the cryptococcal antigen titre which continued to fall after cessation of treatment.

Nasopharyngeal cryptococcosis

Naturally occurring cryptococcosis in five cats, a dog and a koala is described. Involvement of the nasopharynx was documented in all patients, and nasopharyngeal mass lesions accounted for the major presenting complaints in four. Signs referable to nasopharyngeal disease included snoring, stertor, inspiratory dyspnoea and aerophagia. Diagnoses were made by caudal rhinoscopy using a retroverted flexible endoscope, vigorous orthograde flushing with saline, or at necropsy. Concurrent cryptococcal rhinitis was present in all cases, although involvement appeared limited to the caudal nasal cavity in most cases. Typical signs of nasal cavity disease, such as sneezing and nasal discharge, were often absent. Treatment of nasopharyngeal cryptococcosis should include physical dislodgement or debulking of lesion(s) to provide immediate alleviation of upper airway obstruction, followed by systemic antifungal therapy to eliminate residual infection from the nasal cavity. Infections caused by Cryptococcus neoformans var gattii accounted for a disproportionately large number of these cases.

A latex cryptococcal antigen agglutination test for diagnosis and monitoring of therapy for cryptococcosis

A latex cryptococcal antigen agglutination test (LCAT) was performed on sera obtained during the first 14 days of treatment from 58 animals (46 cats, 9 dogs, 2 koalas and 1 long billed corella) with cryptococcosis. The same commercial kit was used for all samples, and most serum samples were treated with pronase before testing. Sera from all 58 cases tested positive with the qualitative LCAT protocol (using undiluted sera), while sera from all 26 cats without cryptococcosis tested negative. Titres determined using the quantitative protocol ranged from 1 to > or = 131 072 (median titre between 2048 and 4096), with 57 of 58 cases (including all 8 animals that presented for neurological signs) having titres > or = 2 and thus considered positive according to the manufacturer's recommendations. The LCAT titre was positively correlated with disease severity (r = 0.4169; P = 0.0011), and patients with disseminated skin and/or lymph node involvement had significantly higher titres than those that did not (P = 0.0157). The presence of neurological signs, the species of the patient, concurrent viral disease (in cats) and the biotype of the isolate had no significant association with the LCAT titre. Cats that died of active cryptococcosis despite treatment did not have significantly higher titres (P = 0.3010) than those that responded to treatment. Sequential LCAT determinations obtained in 37 patients during treatment provided a useful quantitative indication of clinical progress, although the decline in titre lagged somewhat behind clinical improvement. Generally, the antigen titre declined by 2 to 4 fold per month during successful therapy. Although there are insufficient data to make unequivocal recommendations, we suggest that either antifungal therapy be continued until the LCAT titre declines to less than 1, or therapy be discontinued after a 32 fold or greater reduction in titre, with periodic monitoring of the serum antigen titre. Treatment of serum samples with pronase substantially increased the sensitivity of the LCAT.

Suspected drug eruption in seven dogs during administration of flucytosine

7 of 8 dogs receiving combination drug therapy consisting of flucytosine together with amphotericin B and/or a triazole for cryptococcosis or aspergillosis developed cutaneous or mucocutaneous eruptions during the course of treatment. Lesions resolved in all cases following discontinuation of flucytosine despite continued administration of other antifungals, suggesting the eruption was referable primarily to the flucytosine component of therapy. Lesions developed 13 to 41 days (median 20 days) after commencing flucytosine (105 to 188 mg/kg/day divided and given every 8 h; median dose rate 150 mg/kg/day). The cumulative dose of flucytosine given prior to the first signs of the drug eruption ranged from 1.7 to 6.8 g/kg (median 2.3 g/kg). The eruptions consisted of depigmentation, followed by ulceration, exudation and crust formation. The scrotum was affected in all 4 male dogs, the nasal plane in 6 of 7 cases, while the lips, vulva, external ear canal and integument were involved in a smaller number of cases. There was considerable variation in the severity of lesions, with changes being most marked when flucytosine was continued for several days after lesions first appeared. Some dogs experienced malaise and inappetence in association with the suspected drug eruption. Healing took a variable period, typically in excess of 2 weeks after discontinuing flucytosine, with up to 2 months being required for total resolution of the lesions. All lesions resolved eventually without scarring or permanent loss of pigment.

Natural environmental sources of Cryptococcus neoformans var. gattii

We sought evidence for new environmental sources of Cryptococcus neoformans var. gattii by random amplification of polymorphic DNA (RAPD) analysis of isolates from 29 animals with a restricted territorial range in five Australian states. Twenty-three of the 29 isolates and 45 of 45 eucalypt isolates tested previously exhibited one RAPD profile, VGI. RAPD profile VGII was identified in 6 of 17 isolates from domesticated species but in none of 12 native species. Four VGII isolates originated from an area of Western Australia with no natural stands of known eucalypt host, indicating the existence of at least one unrecognized natural source of C. neoformans var. gattii.