An Unusual Case of Feline Leishmaniosis With Involvement of the Mammary Glands

Is leishmaniasis the new emerging zoonosis in the world?

Leishmania is a genus of parasitic protozoa that causes a disease called leishmaniasis. Leishmaniasis is transmitted to humans through the bites of infected female sandflies. There are several different species of Leishmania that can cause various forms of the disease, and the symptoms can range from mild to severe, depending on species of Leishmania involved and the immune response of the host. Leishmania parasites have a variety of reservoirs, including humans, domestic animals, horses, rodents, wild animals, birds, and reptiles. Leishmaniasis is endemic of 90 countries, mainly in South American, East and West Africa, Mediterranean region, Indian subcontinent, and Central Asia. In recent years, cases have been detected in other countries, and it is already an infection present throughout the world. The increase in temperatures due to climate change makes it possible for sandflies to appear in countries with traditionally colder regions, and the easy movement of people and animals today, facilitate the appearance of Leishmania species in new countries. These data mean that leishmaniasis will probably become an emerging zoonosis and a public health problem in the coming years, which we must consider controlling it from a One Health point of view. This review summarizes the prevalence of Leishmania spp. around the world and the current knowledge regarding the animals that could be reservoirs of the parasite.

Feline leishmaniosis with focus on ocular manifestation: a case report

BACKGROUND

In Europe, feline leishmaniosis is commonly caused by Leishmania infantum. There is little knowledge regarding pathogenesis, ocular manifestations and long-term follow-ups in cats with leishmaniosis.

FINDINGS

A 6-year-old female, spayed European Shorthair cat was imported from Spain to Germany 2 years prior to its first clinical presentation. The cat showed lethargy, weight loss, ulcerative lesions on the front limbs and high-grade chronic uveitis. The diagnosis of L. infantum infection was based on the cytological finding of amastigotes in skin lesions, positive qPCR of EDTA-blood and positive PCR of a cyto-brush sample from the conjunctiva. Supportive findings included positive serology by IFAT, serum protein capillary electrophoresis with peaks in alpha2- and gamma-globulin sections and marked elevation of SAA. Enucleation had to be performed on day 288 on both eyes because of blindness, glaucoma and high-grade uveitis. Histologically, high numbers of Leishmania spp. amastigotes were found in histiocytes. IFAT and PCR were positive in the aqueous humor in both eyes, respectively. Feline leukemia virus antigen and feline immunodeficiency virus antibody testings were positive. Hematological and biochemical results revealed mild leukocytosis with lymphocytosis, monocytosis and eosinopenia as well as marked elevation of SAA and hyperglobulinemia. The cat was treated with allopurinol, responded well and was still alive at follow-up on day 288 after first presentation. However, enucleation was necessary because of refractory glaucoma and uveitis.  CONCLUSION: For the first time, ocular evidence of Leishmania IgG antibodies was demonstrated in the aqueous humor of both eyes in cats. There is limited knowledge about the pathogenesis, treatment options and outcomes in cats infected with L. infantum. This case report supports the hypothesis that immunosuppression increases the risk of clinical signs of leishmaniasis in cats. Alpha2- and gamma-globulin peaks in serum protein capillary electrophoresis are supportive criteria for the diagnosis of L. infantum infection. SAA is valuable for monitoring. Regarding ophthalmology, uveitis and glaucoma may have a poor prognosis.

Hemogram Findings in Cats from an Area Endemic for Leishmania infantum and Feline Immunodeficiency Virus Infections

Simple Summary

Some cats positive for Leishmania infantum (Li) show clinical signs and clinicopathological changes, including hemogram abnormalities. However, co-infections or co-morbidities are often detected in cats with leishmaniosis, and they can have a role in the clinical abnormalities observed. In feline Leishmania infantum infections and in clinical cases of feline leishmaniosis, a significant association with feline immunodeficiency virus (FIV) has been detected, but the role of this co-infection is controversial. The aims of this study were to retrospectively evaluate hemogram changes in cats from areas endemic for Leishmania infantum and feline immunodeficiency virus infections (Sicily and Calabria regions, Southern Italy) and to analyze the role of both pathogens in the abnormalities detected. A retrospective cross-sectional study was carried out on 496 cats. Hematological changes in cats positive for Leishmania infantum were found, particularly abnormalities compatible with chronic inflammation including moderate anemia, monocytosis, and morphologically activated monocytes. Moreover, some abnormalities, such as thrombocytosis, seem to arise when cats are co-infected with FIV. Feline leishmaniosis should be considered when some hemogram abnormalities compatible with chronic inflammation are detected.

Abstract

In feline Leishmania infantum (Li) infection and in clinical cases of feline leishmaniosis, co-infection with feline immunodeficiency virus (FIV) has been reported. However, the role of the retroviral co-infection in the impairment of feline clinical health is still controversial. The aim of this study was to evaluate hemogram changes in cats from regions endemic for both Li and FIV infection. Four hundred and ninety-six cats tested for Li (EDTA blood polymerase chain reaction and immunofluorescence antibody test) and for FIV infection (enzyme-linked immune assay) were retrospectively evaluated. Hemogram results including blood smear morphological evaluation were statistically compared considering four infection patterns: Li+FIV+, Li+FIV−, Li−FIV+, and Li−FIV−. Significantly lower values of erythrocytes (Li+FIV−: p = 0.0248; Li−FIV+: p = 0.0392) and hemoglobin (Li+FIV: p = 0.0086; Li−FIV+: p = 0.0249) were found in both infections when compared to Li−FIV− cats, and severity of anemia was more frequently moderate in Li-positive cats (p = 0.0206) and severe in FIV infection (p = 0.024). Li infection was associated with monocytosis (p = 0.0013) and morphologically activated monocytes (p = 0.0209). Moreover, FIV infection was associated with the presence of inflammatory leukogram (p = 0.023), and an association between thrombocytosis and the co-infection was found (p = 0.0347). Li infection in cats induces hematological changes compatible with chronic inflammation, some of which are due to co-infection with FIV.

Clinical Case of Feline Leishmaniosis: Therapeutic Approach and Long-Term Follow-Up

Simple Summary

In the present report, clinical, diagnostic, and therapeutical findings observed in a case of feline leishmaniosis (FeL) along with its long-term follow-up data are reported with the aim to provide more evidence-based data on the treatment of this important zoonotic vector-borne disease of cats. The present study represents one of the few reports of FeL with a 28-month follow-up period. This case underlines the effectiveness of allopurinol and highlights how the interruption of treatment frequently leads to relapse, impairing the animal’s health condition and prognosis.

Abstract

The response to allopurinol treatment and survival time of a case of feline leishmaniosis in a FIV co-infected cat is herein reported. In May 2019, a 13-year-old neutered European Shorthair male was referred due to weight loss and exfoliative dermatitis. Lymphadenomegaly and splenomegaly were detected upon clinical inspection, while the presence of several Leishmania infantum amastigotes were detected on splenic and lymphonodal fine needle aspiration (FNA). Allopurinol (10 mg/kg PO q 12 h) was administered. After two months, the cat’s clinical symptoms disappeared, and the owners decided to interrupt the therapy. In February, two reddish nodular fleshy neoformations appeared in both eyes, and amastigotes of Leishmania were detected by cytology on conjunctival swabs. Allopurinol treatment was re-started at the same rate; the ocular lesions regressed in two weeks, and the owner again decided to interrupt the therapy. In July, the patient had a new relapse, but the owner, tired of continuous relapses, refused further treatment of the disease. The cat’s health condition continued to worsen: in October 2021, the ocular lesions appeared again, and in November the patient died. This case underlines the effectiveness of allopurinol and highlights how interruption of treatment frequently leads to relapse, impairing the animal’s health condition and prognosis.

Review and statistical analysis of clinical management of feline leishmaniosis caused by Leishmania infantum

Background

There is limited information about feline leishmaniosis (FeL) management in clinical practice. Leishmania infantum is the species of Leishmania most frequently reported in both dogs and cats in countries of the Mediterranean region (henceforth ‘Mediterranean countries’), Central and South America, and Iran. This study was conducted to provide veterinary clinicians with an updated overview of evidence-based information on leishmaniosis in cats.

Methods

A review was performed using PubMed, Science Direct, Google Scholar and Web of Science. Case reports of FeL caused by L. infantum were sought for the period 1912 to 1 June 2021.

Results

Sixty-three case reports are included in this review. Fifty-nine out of the 63 cats were from Europe, mostly from Mediterranean countries (88.9%). Most of them were domestic short-haired cats (90%) with a mean age of 7.9 years, and had access to the outdoors (77.3%). Sixty-six percent of the cats had comorbidities, of which feline immunodeficiency virus infection was the most frequent (37.7%). Dermatological lesions (69.8%) was the most frequent clinical sign, and hyperproteinemia (46.3%) the most frequent clinicopathological abnormality. Serology was the most performed diagnostic method (76.2%) and was positive for 93.7% of cats. Medical treatment was applied in 71.4% of cats, and allopurinol was the most used drug (74.4%). Survival time was greater for treated cats (520 days; 71.4% of cats) than non-treated cats (210 days; 25.4%).

Conclusions

The majority of the cats had comorbidities, of which feline immunodeficiency virus was the most frequent. Dermatological lesions were frequently reported, and systemic clinical signs and clinicopathological abnormalities were also common. Serology may be useful for the diagnosis of FeL in clinical practice, and a positive titer of ≥ 1/40 may be a useful cut-off for sick cats. The reported treatments and dosages varied, but there was a good clinical response and longer survival in most of the cats treated with allopurinol monotherapy.

Graphical abstract

Canine and Feline Parasitology: Analogies, Differences, and Relevance for Human Health

Cats and dogs are treated as family members by most pet owners. Therefore, a high quality of veterinary care and preventive medicine is imperative for animal health and welfare and for the protection of humans from zoonotic pathogens. There is a general perception of cats being treated as "small dogs," especially in the field of clinical parasitology. As a result, several important differences between the two animal species are not taken into proper consideration and are often overlooked. Dogs and cats are profoundly different under evolutionary, biological, ethological, behavioral, and immunological standpoints. These differences impact clinical features, diagnosis, and control of canine and feline parasites and transmission risk for humans. This review outlines the most common parasitoses and vector-borne diseases of dogs and cats, with a focus on major convergences and divergences, and discusses parasites that have (i) evolved based on different preys for dogs and cats, (ii) adapted due to different immunological or behavioral animal profiles, and (iii) developed more similarities than differences in canine and feline infections and associated diseases. Differences, similarities, and peculiarities of canine and feline parasitology are herein reviewed in three macrosections: (i) carnivorism, vegetarianism, anatomy, genetics, and parasites, (ii) evolutionary adaptation of nematodes, including veterinary reconsideration and zoonotic importance, and (iii) behavior and immune system driving ectoparasites and transmitted diseases. Emphasis is given to provide further steps toward a more accurate evaluation of canine and feline parasitology in a changing world in terms of public health relevance and One Health approach.

Feline Leishmaniosis: An Emerging Public Health Problem

Leishmaniosis is the third most important vector-borne disease in humans, preceded by malaria and lymphatic filariasis, and it is considered endemic in tropical and subtropical areas, where higher temperatures favor development of its vector, sandflies. This zoonotic disease is caused by infection of protozoa Leishmania spp. and the most serious mucocutaneous and visceral form is produced by Leishmania infantum, which predominates in the Mediterranean region. The usual hosts for this parasite are dogs and humans, but an increment in cases of L. infantum infection has been observed in cats in the last years. This increase could be due to the use of sandflies repellents in dogs, obligating the parasite to looking for other hosts. The role of cats in the epidemiology of this disease is unknown, although increase of prevalence of feline leishmaniosis has been observed in endemic areas in the last years. Diagnostic techniques and treatments in cats are not standardized, which makes it difficult to establish prevalence and epidemiology of feline leishmaniosis. Furthermore, the clinical signs and immune response against Leishmania in cats are different to those in dogs, with an observed increment of drug resistance. It is necessary to increase our knowledge about L. infantum infection in cats, including clinical signs, transmission, treatments, and the role of cats in the increasing of zoonoses. Finally, new alternative treatments are required for controlling the spread of this disease in all species of mammals.

Leishmania infantum strains from cats are similar in biological properties to canine and human strains

Zoonotic visceral leishmaniosis is a worldwide severe disease caused by Leishmania infantum, a protozoan that has phlebotomine sand flies as vectors and dogs as primary reservoir hosts. Over the last few decades, cats have been regarded as an indisputable piece within the ecological system in which L. infantum is maintained indefinitely. However, little is known about feline strains, including their phenotypic plasticity and infectivity. In this study, the phenotypic behaviour of seven L. infantum feline strains was compared to those of well-characterised counterparts isolated from two dogs and two humans in terms of growth profile, adaptive capacity under several stress conditions, susceptibility to antileishmanial drugs, and infectivity to host cells. Feline strains displayed a similar growth profile, survival capacity, and ability to infect feline, canine, and human monocyte-derived primary macrophages. Furthermore, multivariate cluster analysis suggested that most strains studied did not display distinctive phenotypic features. To our knowledge, this is the first study to analyse the phenotypic behaviour of feline L. infantum strains. This study brings new insights into the hypothetical role of cats as reservoir hosts of L. infantum since the parasites found in them are phenotypically identical to those of dogs and humans. However, further studies on the transmission dynamics should be encouraged to fully establish the status of cats in the maintenance of L. infantum foci.

Skin Lesions in Feline Leishmaniosis: A Systematic Review

Feline leishmaniosis (FeL) is increasingly reported throughout the world and skin lesions predominate in the clinical picture. There are, however, few evidence-based data on cutaneous feline leishmaniosis and directions are strongly needed for a better management of the disease. In this study, we systematically reviewed what is currently known about the clinical dermatological presentation of FeL through analysis of the literature and, further, by adding unpublished cases managed by Italian veterinary dermatologists. Sixty-six feline cases of cutaneous leishmaniosis published in 33 articles between 1990 and 2020 met the inclusion criteria and were analyzed. Six unpublished cases of cutaneous FeL managed by Italian dermatologists were also reviewed. The majority of cases were reported from South America, followed by Europe and North America. Nodules were the most frequently reported clinical signs and the presence of Leishmania in lesioned skin was assessed mainly by cytology. A total of six Leishmania species have been identified as being responsible for skin lesions. Coinfections by FIV or FeLV were reported in 12.1% and 9.1% of the cases, respectively. Clinical data including treatment have been analyzed and discussed to provide directives for proper management of the disease for which cats may also serve as domestic reservoirs for human infections.

New Epidemiological Aspects of Animal Leishmaniosis in Europe: The Role of Vertebrate Hosts Other Than Dogs

Infection with Leishmania parasites can lead to severe disease in humans and dogs, which act as a reservoir in zoonotic transmission. An increasing number of reports suggest that leishmaniosis is not restricted to dogs, but also affects many other mammalian and avian species. Consequently, this expands the potential reservoir and is of great public and veterinary health concern. The present study reviews, based on a comprehensive search of scientific literature published from 1 January 2001 to 31 December 2020, the currently available information on animal leishmaniosis in vertebrates in Europe, other than dogs and humans. This review provides an exhaustive list of mammals and birds in which infections with or exposure to Leishmania parasites have been detected in European countries. Most cases are reported from the Mediterranean region. Domestic animals, in particular cats, pose a concern because of close contact with humans. The wildlife reservoir is less likely to contribute to zoonotic transmission, with the exception of hares. This potentially large reservoir needs to be taken into account when developing control measures for zoonotic leishmaniosis. From a veterinary point of view, it is important that veterinarians are better aware of leishmaniosis and trained in its management.

Leishmania infection in cats and feline leishmaniosis: An updated review with a proposal of a diagnosis algorithm and prevention guidelines

Leishmaniosis is a vector-borne disease caused by protozoans of the genus Leishmania, which are transmitted to vertebrates, including cats, through the bites of female phlebotomine sand flies. An increasing number of epidemiological and experimental studies concerning Leishmania infection in cats, as well as case reports of clinical leishmaniosis in these felids, have been published in recent years. In the present study, a comprehensive review was made by sourcing the National Library of Medicine resources to provide updated data on epidemiology, immunopathogenesis, diagnosis, treatment, and prevention of feline leishmaniosis. Cats were found infected with Leishmania parasites worldwide, and feline leishmaniosis appears as an emergent disease mostly reported in countries surrounding the Mediterranean Sea and in Brazil. Cats with impaired immunocompetence seem to have a higher risk to develop clinical disease. The main clinical and clinicopathological findings are dermatological lesions and hypergammaglobulinemia, respectively. Diagnosis of feline leishmaniosis remains a challenge for veterinarians, in part due to the lack of diagnosis support systems. For this reason, a diagnostic algorithm for clinical decision support is herein proposed. No evidence-based treatment protocols are currently available, and these remain empirically based. Control measures are limited and scarce. Thus, a set of prevention guidelines are herein suggested.