ABCD: Update of the 2009 guidelines on prevention and management of feline infectious diseases

OVERVIEW

In this article, the ABCD guidelines published in the JFMS Special Issue of July 2009 (Volume 11, Issue 7, pages 527-620) are updated by including previously unavailable and novel information. For a better picture, the reader is advised to consult that issue before focusing on the novel features.

Leptospira species infection in cats: ABCD guidelines on prevention and management

OVERVIEW

Leptospirosis is a bacterial disease affecting a variety of domestic and wild animals as well as humans worldwide. Leptospirosis has been reported in over 150 mammalian species. It is considered an emerging infectious disease in humans and in dogs. Subclinically infected wild and domestic animals serve as reservoir hosts and are a potential source of infection for incidental hosts and humans.

INFECTION

Reports of leptospirosis in cats are rare, but the importance of cats shedding Leptospira species and serving as a source of infection has recently gained attention. Leptospira species antibodies are commonly present in the feline population, and Leptospira species shedding of cats with outdoor exposure has been demonstrated. Cats mostly become infected through transmission from hunting rodents.

SIGNIFICANCE

The role of healthy carrier cats as a source of contamination, as well as the role of leptospires as a pathogen in cats, are likely underestimated.

Capnocytophaga canimorsus infection in cats: ABCD guidelines on prevention and management

OVERVIEW

Capnocytophaga canimorsus and Capnocytophaga cynodegmi are part of the normal bacterial flora of the oral cavity of dogs and cats. C canimorsus is more pathogenic and causes more severe infections in humans.

INFECTION

Disease is less frequently seen after a cat bite, scratch or close contact than after dog contacts. Serious disease has been reported in people, especially associated with immunocompromise and alcoholism. Disease in cats is not well documented; two cases of respiratory infection have been associated with the presence of these bacteria.

DIAGNOSIS

Diagnosis is based on culture in specific media, but these are slow growing bacteria; polymerase chain reaction and sequencing may aid in diagnosis and species identification.

TREATMENT

Penicillin or beta-lactams are the treatment options of choice. ZOONOTIC POTENTIAL: Based on incidence surveys, the zoonotic potential is low. The risk may be higher for immunocompromised persons, where dog and cat ownership must be discussed.

Aujeszky's disease/pseudorabies in cats: ABCD guidelines on prevention and management

OVERVIEW

Although pseudorabies in swine - Aujeszky's disease - has been eradicated from many pork-producing countries, the virus may still lurk in other vertebrate species and cause feline cases. Infection occurs through the ingestion of uncooked meat and organ material and presents as an acute encephalitis with a short incubation period and a rapidly fatal outcome. The ABCD considers this reason enough to include a review of this, now very rare, condition in this Special Issue.

Babesiosis in cats: ABCD guidelines on prevention and management

OVERVIEW

Babesiosis is a tick-borne protozoan disease caused by parasites of the genus Babesia that belong to the Piroplasmida. The disease is named after the Romanian bacteriologist Victor Babeş. Babesiosis is also known as piroplasmosis (from Latin pirum, meaning 'pear', and plasma, 'image, formation').

INFECTION

Babesiosis affects domestic and wild animals and humans worldwide. While the disease is recognised in dogs around the world, it is found only rarely in cats. HUMAN DISEASE: Babesia species are common blood parasites of mammals. Human babesiosis is uncommon, but more cases in people have been reported recently, most likely because of rising awareness.

Cryptococcosis in cats: ABCD guidelines on prevention and management

OVERVIEW

Cryptococcosis is worldwide the most common systemic fungal disease in cats; it is caused by the Cryptococcus neoformans- Cryptococcus gattii species complex, which includes eight genotypes and some subtypes (strains) with varying geographical distribution, pathogenicity and antimicrobial susceptibility. Cats acquire the infection from a contaminated environment. The prognosis is favourable in most cases, provided a diagnosis is obtained sufficiently early and prolonged treatment is maintained.

INFECTION

Basidiospores are the infectious propagules of Cryptococcus species as they penetrate the respiratory system and induce primary infection. Asymptomatic colonisation of the respiratory tract is more common than clinical disease. Avian guanos, particularly pigeon droppings, offer favourable conditions for the reproduction of C neoformans. Both Cryptococcus species are associated with decaying vegetation.

DISEASE SIGNS

Cryptococcosis caused by C neoformans or C gattii is indistinguishable clinically. The disease can present in nasal, central nervous system (which can derive from the nasal form or occur independently), cutaneous and systemic forms.

DIAGNOSIS

An easy and reliable test for cryptococcosis diagnosis is antigen detection in body fluids. Only isolation and polymerase chain reaction allow identification of the species genotype.

DISEASE MANAGEMENT

Amphotericin B, ketoconazole, fluconazole and itraconazole have all been used to treat cats. Surgical excision of any nodules in the skin, nasal or oral mucosa assists recovery. Continued treatment is recommended until the antigen test is negative.

PREVENTION

Efficient preventive measures have not been demonstrated. Vaccines are not available.

Cowpox Virus Infection in Cats

Overview:

The misnomer ‘cowpox’ has historical roots: cats rather acquire the virus from small rodents. It has a wide host spectrum (including man) and causes skin lesions, predominantly on the head and paws. Progressive proliferative ulcerations in kittens and immunosuppressed cats may take a fatal course. Cat owners should be informed about the zoonotic risk.

Bartonella Species Infection in Cats

Overview:

Over 22 Bartonella species have been described in mammals, and Bartonella henselae is most common worldwide. Cats are the main reservoir for this bacterium. B henselae is the causative agent of cat scratch disease in man, a self-limiting regional lymphadenopathy, but also of other potentially fatal disorders in immunocompromised people.

Infection:

B henselae is naturally transmitted among cats by the flea Ctenocephalides felis felis, or by flea faeces. A cat scratch is the common mode of transmission of the organism to other animals, including humans. Blood transfusion also represents a risk.

Disease signs:

Most cats naturally infected by B henselae do not show clinical signs but cardiac (endocarditis, myocarditis) or ocular (uveitis) signs may be found in sporadic cases. B vinsonii subspecies berkhoffii infection has reportedly caused lameness in a cat affected by recurrent osteomyelitis and polyarthritis.

Diagnosis:

Isolation of the bacterium is the gold standard, but because of the high prevalence of infection in healthy cats in endemic areas, a positive culture (or polymerase chain reaction) is not confirmatory. Other compatible diagnoses must be ruled out and response to therapy gives a definitive diagnosis. Serology (IFAT or ELISA) is more useful for exclusion of the infection because of the low positive predictive value (39–46%) compared with the good negative predictive value (87–97%). Laboratory testing is required for blood donors.

Disease management:

Treatment is recommended in the rare cases where Bartonella actually causes disease.

Prevention of infectious diseases in cat shelters

Overview:

Recommendations are given in relation to infectious diseases in rescue shelters. The ABCD recognises that there is a wide variation in the design and management of shelters, and that these largely reflect local pressures. These guidelines are written with this diverse audience in mind; they point to the ideal, and also provide for some level of compromise where this ideal cannot immediately be attained. In addition consideration should be given to general requirements in order to optimise overall health and wellbeing of cats within the shelter.

Housing:

Compartmentalisation of the shelter into at least three individual sections (quarantine area for incoming cats, isolation facilities for sick or potentially infectious cats, and accommodation for clinically healthy, retrovirus-negative cats) can facilitate containment of a disease outbreak, should it occur.

Standard of care:

Incoming cats should receive a full health check by a veterinary surgeon, should be dewormed and tested for retrovirus infections (feline leukaemia virus [FeLV] and/or feline immunodeficiency virus [FIV]) in regions with high prevalence and in shelters that allow contact between cats. Cats which are not rehomed should receive a regular veterinary check-up at intervals recommended by their veterinarian.

Vaccination:

Each cat should be vaccinated as soon as possible against feline panleukopenia virus (FPV), feline herpesvirus (FHV-1) and feline calicivirus (FCV) infections.

Hygiene:

Adequate hygiene conditions should ensure that contact between shedders of infectious agents and susceptible animals is reduced as efficiently as possible by movement control, hygiene procedures of care workers, barrier nursing, cleaning and disinfection.

Stress reduction:

Stress reduction is important for overall health and for minimising the risk of recrudescence and exacerbation of infectious diseases. In general, a special effort should be made to rehome cats as soon as possible.

Giardiasis in cats

Overview:

Giardia is a protozoan parasite that infects the small intestine of cats and can cause diarrhoea. The biotypes that affect cats do not appear to infect humans. Infection is most common in young cats, particularly from multicat backgrounds.

Disease signs:

Infected cats that develop clinical signs show small intestinal diarrhoea and there may be associated weight loss.

Diagnosis:

Diagnosis of infection is usually based on an in-practice ELISA for faecal antigen or zinc sulphate flotation of several pooled faecal samples. Polymerase chain reaction (PCR) tests are available but not used so widely. Infection can be detected in clinically healthy cats so interpretation of a positive result in cats with diarrhoea requires care.

Treatment:

Fenbendazole or metronidazole are regarded as the treatments of choice. Secondary gut changes may be slow to resolve and so diarrhoea may continue for some time after infection has been eliminated.

Rare systemic mycoses in cats: blastomycosis, histoplasmosis and coccidioidomycosis

Overview:

Rare fungal infections, including those hitherto not reported in Europe, may occur sporadically in non-endemic areas, or imported cases may be seen.

Infections:

Blastomycosis is mainly seen in North America; no cases have been reported in Europe. Histoplasmosis, which is endemic in the eastern US, Central and South America, has been diagnosed in Japan and Europe. Coccidioidomycosis is endemic in the southwestern US, Central and South America; only one imported case has been reported in Europe. The primary mode of transmission is inhalation of conidia or spores from the environment.

Disease signs:

Most feline cases present with a combination of clinical signs (mainly respiratory, along with skin, eye, central nervous system and bone). Lymphadenopathy and systemic signs may be present.

Diagnosis:

Diagnosis is based on fungal detection by cytology and/or histology. Commercial laboratories do not routinely perform fungal culture. Diagnosis of coccidioidomycosis, which is more difficult, may be supported by antibody detection.

Treatment:

Treatment consists of prolonged systemic antifungal therapy, with itraconazole as the first-choice agent for histoplasmosis and blastomycosis. The prognosis is good if owner compliance is adequate and adverse drug effects do not occur.

Prevention:

Cat owners travelling to endemic areas should be warned about these diseases. There is no zoonotic risk.

Rare opportunistic mycoses in cats: phaeohyphomycosis and hyalohyphomycosis

Overview:

Phaeohyphomycoses and hyalohyphomycoses are rare opportunistic infections acquired from the environment. More cases have been reported in recent years in humans and cats.

Disease signs:

Single or multiple nodules or ulcerated plaques (which may be pigmented) in the skin are the typical lesions. In some cases the infection disseminates or involves the central nervous system (CNS).

Diagnosis:

Diagnosis is based on fungal detection by cytology and/or histology. Culture provides definitive diagnosis and species identification.

Treatment:

Treatment involves surgical excision in cases of localised skin disease followed by systemic antifungal therapy, with itraconazole as the agent of first choice. Relapses after treatment are common. Itraconazole and other systemic antifungal agents have been used to treat systemic or neurological cases, but the response is unpredictable. The prognosis is guarded to poor in cats with multiple lesions and systemic or neurological involvement.

Zoonotic risk:

There is no zoonotic risk associated with contact with infected cats.

Feline Viral Papillomatosis

Overview:

Papillomaviruses are epitheliotropic and cause cutaneous lesions in man and several animal species, including cats.

Infection:

Cats most likely become infected through lesions or abrasions of the skin. Species-specific viruses have been detected but human and bovine related sequences have also been found, suggesting cross-species transmission.

Clinical signs:

In cats, papillomaviruses are associated with four different skin lesions: hyperkeratotic plaques, which can progress into Bowenoid in situ carcinomas (BISCs) and further to invasive squamous cell carcinomas (ISCCs); cutaneous fibropapillomas or feline sarcoids; and cutaneous papillomas. However, papillomaviruses have also been found in normal skin.

Diagnosis:

Papillomavirus-induced skin lesions can be diagnosed by demonstration of papillomavirus antigen in biopsies of skin lesions, or detection of papillomavirus-like particles by electron microscopy and papillomavirus DNA by polymerase chain reaction (PCR).

Treatment:

Spontaneous regression might be expected. In cases of ISCC, complete excision should be considered if possible.

Francisella Tularensis Infection in Cats

Overview:

Disease in cats after infection with the zoonotic bacterium Francisella tularensis has been reported only from North America; rodents and lagomorphs are the more susceptible hosts. Tularaemia is transmitted by ticks, but also acquired by direct contact, bite, scratch, ingestion or inhalation. Clinical signs range from mild chronic localised infections to fatal acute disease; antibiotic therapy is efficient. Acquiring the infection from cats is a risk for owners of outdoor cats, veterinarians and technicians.

Dermatophytosis in Cats

Overview:

Dermatophytosis, usually caused by Microsporum canis, is the most common fungal infection in cats worldwide, and one of the most important infectious skin diseases in this species. Many adult cats are asymptomatic carriers. Severe clinical signs are seen mostly in kittens or immunosuppressed adults. Poor hygiene is a predisposing factor, and the disease may be endemic in shelters or catteries. Humans may be easily infected and develop a similar skin disease.

Infection:

Infectious arthrospores produced by dermatophytes may survive in the environment for about a year. They are transmitted through contact with sick cats or healthy carriers, but also on dust particles, brushes, clothes and other fomites.

Disease signs:

Circular alopecia, desquamation and sometimes an erythematous margin around central healing (‘ringworm’) are typical. In many cats this is a self-limiting disease with hair loss and scaling only. In immunosuppressed animals, the outcome may be a multifocal or generalised skin disease.

Diagnosis:

Wood’s lamp examination and microscopic detection of arthrospores on hairs are simple methods to confirm M canis infection, but their sensitivity is relatively low. The gold standard for detection is culture on Sabouraud agar of hairs and scales collected from new lesions.

Disease management:

In shelters and catteries eradication is difficult. Essential is a combination of systemic and topical treatments, maintained for several weeks. For systemic therapy itraconazole is the drug of choice, terbinafine an alternative. Recommended topical treatment is repeated body rinse with an enilconazole solution or miconazole with or without chlorhexidine. In catteries/shelters medication must be accompanied by intensive decontamination of the environment.

Vaccination:

Few efficacy studies on anti- M canis vaccines (prophylactic or therapeutic) for cats have been published, and a safe and efficient vaccine is not available.

Aspergillosis in Cats

Overview:

Aspergillosis is a sporadic mycosis that occurs worldwide in mammals and birds and leads to a usually chronic, and only rarely acute, disease that mainly affects the nasal cavity and sinuses.

Infection:

Aspergillus species infections are commonly associated with predisposing local or systemic factors. Local disease can spread and involve the central nervous system or the lungs. Some Aspergillus species can also disseminate, causing systemic infections. In contrast to dogs, in which (nasal) aspergillosis is relatively common, aspergillosis is rare in cats, but considered an emerging infection.

Clinical signs:

There are two clinical forms of aspergillosis in cats, the sinonasal form (characterised by signs of chronic nasal infection) and the newly emerging, more invasive sino-orbital form (characterised by signs of orbital and surrounding tissue invasion). Sino-orbital involvement has been described now in approximately half of the reported cases.

Disease management:

Treatment should consist of local and systemic antifungal therapy.

Yersinia Pestis Infection in Cats

Overview:

Plague, the medieval ‘Black Death’, is caused by a Gram-negative coccobacillus, Yersinia pestis, which also infects cats. As in people, it is transmitted from rodents through flea bites; it occurs in Asia, Africa and the Americas in flea-infested regions, all year round, and where rodent reservoirs are abundant. A poor prognosis is associated with high fever, and the pulmonary and septicaemic forms. Antibiotic therapy, flea control and avoidance of rodent contacts have made this infection manageable.

Tritrichomoniasis in Cats

Overview:

Tritrichomonas foetus is a protozoan organism that is specific to cats and can cause large bowel diarrhoea. It is distinct from other Tritrichomonas species and not considered to be zoonotic. Infection is most common in young cats from multicat households, particularly pedigree breeding catteries.

Disease signs:

Affected cats show frequent fetid diarrhoea, often with mucus, fresh blood and straining, but generally remain bright and do not lose weight.

Diagnosis:

Diagnosis of infection is usually based on direct microscopic examination of freshly voided faeces. Polymerase chain reaction (PCR) testing is more sensitive but may detect infections unrelated to diarrhoea and, therefore, requires care in interpretation.

Treatment:

The treatment of choice is ronidazole, which should be used with care as it is an unlicensed drug for cats with a narrow safety margin. Clinical signs are generally self-limiting in untreated cases, but may take months to resolve.

Coxiellosis/Q Fever in Cats

Overview:

Q fever is a zoonotic disease caused by Coxiella burnetii. Farm animals and pets are the main reservoirs of infection.

Infection:

Cats become infected by ingestion or inhalation of organisms from contaminated carcases of farm animals, or tick bites. Infection is common, as shown by several serological studies.

Clinical signs:

Experimentally, fever, anorexia and lethargy have been noted. In the field, infection usually remains subclinical. Abortion might occur. C burnetii has been isolated from the placenta of aborting cats, but also from cats experiencing normal parturition.

Diagnosis:

Infection with C burnetii can be diagnosed by isolation of the agent or serology.

Prevention:

Most important is the potential zoonotic risk. Cats suspected of having been exposed to C burnetii might shed organisms during parturition. Wearing gloves and a mask when attending parturient or aborting cats can minimise the risk of infection. Tick prevention is recommended.

Mycobacterioses in Cats

Overview:

Mycobacterial infections are important in humans and animals. Cats can be infected by several Mycobacterium species, which may cause different syndromes, mainly tuberculosis, atypical or non-tuberculous mycobacteriosis and leprosy. In recent years, awareness has increased about how to recognise and confirm these infections. More cases are diagnosed today, which probably means that the disease has escaped detection in the past.

Infection:

Most cases in cats are cutaneous, presenting as nodules in the skin and draining tracts, ulceration and local lymphadenopathy; however, systemic dissemination may also occur.

Diagnosis:

Definitive diagnosis is difficult when the bacterium cannot be detected by histology or culture. However, species confirmation is essential for treatment and prognosis, so material for culture and polymerase chain reaction should be submitted in every suspected case.

Treatment:

Treatment is challenging. A combination of two or three antibiotics is needed, and treatment must be continued for some months, which makes owner compliance especially difficult in cats.

Zoonotic risk:

There is a zoonotic risk associated with some mycobacterial species. Concerns should be communicated in every case of an immunocompromised owner in contact with an infected cat.

Characterisation of the genomes of four putative vesiculoviruses: tench rhabdovirus, grass carp rhabdovirus, perch rhabdovirus and eel rhabdovirus European X

The complete coding sequences were determined for four putative vesiculoviruses isolated from fish. Sequence alignment and phylogenetic analysis based on the predicted amino acid sequences of the five main proteins assigned tench rhabdovirus and grass carp rhabdovirus together with spring viraemia of carp and pike fry rhabdovirus to a lineage that was distinct from the mammalian vesiculoviruses. Perch rhabdovirus, eel virus European X, lake trout rhabdovirus 903/87 and sea trout virus were placed in a second lineage that was also distinct from the recognised genera in the family Rhabdoviridae. Establishment of two new rhabdovirus genera, "Perhabdovirus" and "Sprivivirus", is discussed.

Phylogeny and prevalence of kobuviruses in dogs and cats in the UK

The kobuviruses represent an emerging genus in the Picornaviridae. Here we have used next generation sequencing and conventional approaches to identify the first canine kobuvirus (CaKoV) from outside the USA. Phylogenetic analysis suggests that a single lineage genotype of CaKoV now exists in Europe and the USA with 94% nucleotide similarity in the coding region. CaKoV was only identified in a single case from a case–control study of canine diarrhoea, suggesting this virus was not a frequent cause of disease in this population. Attempts to grow CaKoV in cell culture failed. Sequence analysis suggested CaKoV was distinct from human Aichi virus (AiV), and unlikely to pose a significant zoonotic risk. Serosurveys by ELISA, immunofluorescence and neutralisation tests, using AiV as antigen, suggested kobuvirus infection is prevalent in dogs. In addition, IgG antibody to AiV was also detected in cat sera, indicating for the first time that cats may also be susceptible to kobuvirus infection.

Analysis of gene expression from the Wolbachia genome of a filarial nematode supports both metabolic and defensive roles within the symbiosis

The α-proteobacterium Wolbachia is probably the most prevalent, vertically transmitted symbiont on Earth. In contrast with its wide distribution in arthropods, Wolbachia is restricted to one family of animal-parasitic nematodes, the Onchocercidae. This includes filarial pathogens such as Onchocerca volvulus, the cause of human onchocerciasis, or river blindness. The symbiosis between filariae and Wolbachia is obligate, although the basis of this dependency is not fully understood. Previous studies suggested that Wolbachia may provision metabolites (e.g., haem, riboflavin, and nucleotides) and/or contribute to immune defense. Importantly, Wolbachia is restricted to somatic tissues in adult male worms, whereas females also harbor bacteria in the germline. We sought to characterize the nature of the symbiosis between Wolbachia and O. ochengi, a bovine parasite representing the closest relative of O. volvulus. First, we sequenced the complete genome of Wolbachia strain wOo, which revealed an inability to synthesize riboflavin de novo. Using RNA-seq, we also generated endobacterial transcriptomes from male soma and female germline. In the soma, transcripts for membrane transport and respiration were up-regulated, while the gonad exhibited enrichment for DNA replication and translation. The most abundant Wolbachia proteins, as determined by geLC-MS, included ligands for mammalian Toll-like receptors. Enzymes involved in nucleotide synthesis were dominant among metabolism-related proteins, whereas the haem biosynthetic pathway was poorly represented. We conclude that Wolbachia may have a mitochondrion-like function in the soma, generating ATP for its host. Moreover, the abundance of immunogenic proteins in wOo suggests a role in diverting the immune system toward an ineffective antibacterial response.

Application of next-generation sequencing technologies in virology

The progress of science is punctuated by the advent of revolutionary technologies that provide new ways and scales to formulate scientific questions and advance knowledge. Following on from electron microscopy, cell culture and PCR, next-generation sequencing is one of these methodologies that is now changing the way that we understand viruses, particularly in the areas of genome sequencing, evolution, ecology, discovery and transcriptomics. Possibilities for these methodologies are only limited by our scientific imagination and, to some extent, by their cost, which has restricted their use to relatively small numbers of samples. Challenges remain, including the storage and analysis of the large amounts of data generated. As the chemistries employed mature, costs will decrease. In addition, improved methods for analysis will become available, opening yet further applications in virology including routine diagnostic work on individuals, and new understanding of the interaction between viral and host transcriptomes. An exciting era of viral exploration has begun, and will set us new challenges to understand the role of newly discovered viral diversity in both disease and health.