Leishmania Infection in Wild Lagomorphs and Domestic Dogs in North-East Spain

Leishmania infantum is a zoonotic protozoan parasite distributed worldwide that is transmitted by phlebotomine sandflies. Dogs are the main reservoir for human infections. However, in recent years, the capacity of lagomorphs to contribute to Leishmania transmission has been confirmed. The present study aimed to assess Leishmania spp. exposure and infection in lagomorphs and sympatric domestic dogs in NE Spain. Sera from European hares, European rabbits, and rural dogs were tested for antibodies against L. infantum using an in-house indirect ELISA. PCR analysis targeting Leishmania spp. was performed in spleens from L. europaeus. Antibodies against Leishmania spp. were detected in all the species analyzed. Total sample prevalence was significantly higher in O. cuniculus (27.9%) than in L. europaeus (2.0%). Results of the PCR were all negative. The present study expands knowledge about Leishmania infections in free-ranging lagomorphs in the Iberian Peninsula, suggesting a more important role of O. cuniculus in the study area. Given the strong correlation between lagomorph densities and human leishmaniasis outbreaks in Spain, the high rabbit and human densities in NE Spain, and the high Leishmania spp. seroprevalence in rabbits, it becomes imperative to establish surveillance programs for lagomorphs in this region.

Effect of storage on the nitro blue tetrazolium reduction test in dog blood samples

INTRODUCTION

The nitro blue tetrazolium (NBT) reduction test (NBTT) has been used for measuring the metabolic activity of phagocytes of mammals. Activated neutrophils transform NBT into formazan in the cytoplasm. The NBTT can detect the activation of neutrophils in peripheral blood and is used to assess neutrophil function in dogs. However, the NBTT is not used frequently in the clinical setting, as samples should be processed after blood collection.

OBJECTIVE

The aim of this study was to evaluate the effect of storage on NBTT in dog blood samples.

MATERIALS AND METHODS

Residual EDTA blood samples from 22 dogs were included of different ages, breeds, and sex. The buffy coat layer was separated from the blood and incubated with 0.1% NBT. The NBTT was performed at 0, 24, 48, and 72 h after the collection of blood. Blood samples were stored at 4°C until the tests were performed. Blood smears were evaluated by light microscopy, and the NBT reduction rate was reported, which represents the percentage of activated neutrophils. The NBT reduction rate was calculated after counting 300 neutrophils in each slide.

RESULTS

The means of NBTT in dog blood samples at 0, 24, 48, and 72 h were 8.3%, 8.5%, 8.7%, and 7.8%, respectively. No significant differences were observed between time points.

CONCLUSIONS

This study showed that the NBTT can be performed up to 72 h after the collection of canine blood if correctly refrigerated at 4°C. This finding supports the performance of the NBTT in the clinical setting.

A blinded, randomized and controlled multicenter clinical trial to assess the efficacy and safety of Leisguard® as an immunotherapeutic treatment for healthy Leishmania infantum-seropositive dogs

BACKGROUND

Domperidone (Leisguard®) is an immunomodulatory drug used as a preventive measure in healthy dogs. However, no studies have been published in healthy Leishmania infantum-seropositive dogs. The aim of this study was to evaluate the clinical efficacy and safety of domperidone as immunotherapy in Leishmania-seropositive healthy dogs.

METHODS

Sixty-seven dogs were treated with domperidone at 0.5 mg/kg and 44 dogs received placebo, once daily for 4 consecutive weeks. Monthly treatments were repeated every 4 months until the end of the 1-year follow-up period. Veterinary examinations were performed on days 0, 30, 120, 150, 240, 270 and 360. Samples of blood and urine were collected on days 0, 120, 240 and 360 for routine laboratory tests and quantitative in-house ELISA for the detection of L. infantum-specific antibodies. Furthermore, Leishmania real-time PCR and IFN-γ ELISA were performed at day 0 and the end of the study. Dogs that developed disease were withdrawn from the study and classified as sick dogs. Adverse drug reactions were reported.

RESULTS

Thirty dogs developed disease during the follow-up period: 13/67 (19.4%) in the group treated with domperidone and 17/44 (38.6%) in the placebo-treated group (P = 0.03). Low-seropositive dogs treated with domperidone (4/40, 9.1%) were significantly less likely to develop disease compared to low-seropositive dogs treated with placebo (7/24, 29.2%; P = 0.04), while no differences were found between domperidone (9/23, 39.1%) and placebo (10/20, 50%) in medium- to high-seropositive dogs. At the end of the study, a higher proportion of Leishmania PCR-positive dogs was observed in the placebo-treated group (16/33, 48.5%) compared to the domperidone group (13/51, 25.5%; P = 0.04). Furthermore, low-seropositive dogs treated with domperidone with an increase of IFN-γ concentration presented a higher increase than those treated with placebo at the end of the study. Four dogs treated with domperidone presented self-limiting diarrhea.

CONCLUSIONS

Healthy dogs with low L. infantum antibody levels treated with domperidone were less likely to develop disease compared to placebo-treated dogs. Furthermore, domperidone presented a good safety profile.

Exploring the Relationship between Neutrophil Activation and Different States of Canine L. infantum Infection: Nitroblue Tetrazolium Test and IFN-γ

This study aimed to investigate the role of neutrophils in canine leishmaniosis by assessing neutrophil activation and its relationship with different states of L. infantum infection and antibody and IFN-γ production. Dogs were categorized into five groups: healthy-seronegative (n = 25), healthy-seropositive (n = 21), LeishVet-stage I (n = 25), Leishvet-stage II (n = 41), and LeishVet-stage III-IV (n = 16). Results of the nitroblue tetrazolium reduction test (NBT) showed significantly higher neutrophil activation in stage I (median:17.17, range: [7.33-31.50]%) compared to in healthy-seronegative (4.10 [1.20-18.00]%), healthy-seropositive (7.65 [3.98-21.74]%), stage II (6.50 [1.50-28.70]%), and stage III-IV (7.50 [3.00-16.75]%) groups (p < 0.0001). Healthy-seropositive dogs also displayed higher values than all groups except stage I. Stages II and III-IV did not show significant differences compared to healthy-seronegative. Regarding IFN-γ, stage I dogs had higher concentrations (median:127.90, range: [0-3998.00] pg/mL) than healthy-seronegative (0 [0-109.50] pg/mL) (p = 0.0002), stage II (9.00 [0-5086.00] pg/mL) (p = 0.045), and stage III-IV (3.50 [80.00-548.80] pg/mL) (p = 0.02) dogs. Stage II dogs showed increased IFN-γ compared to healthy-seronegative dogs (p = 0.015), while stage III-IV dogs had no significant differences compared to healthy-seronegative dogs (p = 0.12). Healthy-seropositive dogs had elevated IFN-γ concentrations compared to healthy-seronegative dogs (p = 0.001) and dogs in stage III-IV (p = 0.03). In conclusion, neutrophil activation was higher in dogs with mild disease and healthy-seropositive dogs, and a relationship between neutrophil activation and the production of IFN-γ was found.

Needle tract seeding and malignant transformation of hepatocellular adenoma into well-differentiated hepatocellular carcinoma in a dog

An 11-year-old neutered female Golden Retriever was referred for investigation of marked increases in liver enzyme activities. Abdominal ultrasound revealed a large pedunculated liver mass. Diagnosis of hepatocellular adenoma (HCA) was made when the mass was excised after a first unsuccessful attempt through ultrasound-guided core-needle biopsy. One and a half years after presentation, a nodule embedded between muscles of the abdominal wall appeared. The mass was first diagnosed as a well-differentiated hepatocellular carcinoma (HCC) through cytologic examination, which was later confirmed with histopathology. Ki 67 immunostaining of the abdominal wall nodule showed an increased immunoreactivity compared with the liver mass. Therefore, the present case documents the first needle-tract seeding of a hepatocellular epithelial tumor with possible malignant transformation of HCA into a well-differentiated HCC in a dog.

Effect of Local Administration of Meglumine Antimoniate and Polyhexamethylene Biguanide Alone or in Combination with a Toll-like Receptor 4 Agonist for the Treatment of Papular Dermatitis due to Leishmania infantum in Dogs

Papular dermatitis is a cutaneous manifestation of canine Leishmania infantum infection associated with mild disease. Although it is a typical presentation, nowadays, there is still no established treatment. This study evaluated the safety and clinical efficacy of local meglumine antimoniate, locally administered polyhexamethylene biguanide (PHMB) alone or PHMB in combination with a Toll-like receptor 4 agonist (TLR4a) for the treatment of papular dermatitis due to L. infantum and assessed parasitological and immunological markers in this disease. Twenty-eight dogs with papular dermatitis were divided randomly into four different groups; three of them were considered treatment groups: PHMB (n = 5), PHMB + TLR4a (n = 4), and meglumine antimoniate (n = 10)), and the remaining were considered the placebo group (n = 9), which was further subdivided into two sub-groups: diluent (n = 5) and TLR4a (n = 4). Dogs were treated locally every 12 h for four weeks. Compared to placebo, local administration of PHMB (alone or with TLR4a) showed a higher tendency towards resolution of papular dermatitis due to L. infantum infection at day 15 (χ² = 5.78; df = 2, p = 0.06) and day 30 (χ² = 4.; df = 2, p = 0.12), while local meglumine antimoniate administration demonstrated the fastest clinical resolution after 15 (χ² = 12.58; df = 2, p = 0.002) and 30 days post-treatment (χ² = 9.47; df = 2, p = 0.009). Meglumine antimoniate showed a higher tendency towards resolution at day 30 when compared with PHMB (alone or with TLR4a) (χ² = 4.74; df = 2, p = 0.09). In conclusion, the local administration of meglumine antimoniate appears to be safe and clinically efficient for the treatment of canine papular dermatitis due to L. infantum infection.

Signalment, Immunological and Parasitological Status and Clinicopathological Findings of Leishmania-Seropositive Apparently Healthy Dogs

Canine leishmaniosis caused by Leishmania infantum is a disease with a wide range of clinical manifestations. Epidemiological serosurveys performed in Europe often lack a thorough assessment of clinical health status of studied dogs. The aim of this study was to evaluate signalment, immunological and parasitological status and clinicopathological findings of L. infantum-seropositive apparently healthy dogs (n = 212) living in endemic areas. Routine laboratory tests, endpoint in-house ELISA to quantify the anti-Leishmania antibodies, blood Leishmania qPCR and IFN-γ ELISA were performed. All dogs enrolled were L. infantum-seropositive and were classified as healthy (n = 105) or sick (n = 107) according to LeishVet guidelines. The sick group presented a higher proportion of medium to high antibody levels and positive qPCR and lower IFN-γ concentration compared to the healthy group. Sick dogs were mostly classified in LeishVet stage IIa. Biochemical alterations (98%) were the most common clinicopathological findings, with fewer urinary tract (46%) and hematological (40%) alterations. Apparently healthy L. infantum-seropositive dogs can be classified between truly healthy dogs and sick dogs with clinicopathological findings. Sick dogs presented medium to high seropositivity and parasitemia and low IFN-γ concentrations, and their most common clinicopathological abnormalities were serum protein alterations followed by proteinuria and lymphopenia.

Clinicopathological findings and risk factors associated with Cytauxzoon spp. infection in cats: A case-control study (2008–2021)

In Europe, Cytauxzoon spp. infection was documented in domestic and wild felids. Cats often develop a subclinical infection, while fatal disease is rare. Currently, information on the epidemiology, risk factors and clinicopathological findings of Cytauxzoon spp. infection remains limited and obtained by a single subject or small groups of cats. The objective of this case-control study was to evaluate clinicopathological findings and to describe risk factors associated with Cytauxzoon spp. infection in domestic cats. Infected cats (n = 39) and non-infected (n = 190) cats were selected from the database of the referral San Marco Veterinary Laboratory between 2008 and 2021. Demographic information, a preset questionnaire considering lifestyle, environment, and clinical status, and a CBC performed contextually with the PCR analysis were recorded for all cats. Data on the biochemical profile and serum protein electrophoresis were also evaluated when available. Compared to the control group, infection was more likely to occur in stray cats (24/39, 61.5%, P &lt; 0.001), living totally/partially outdoors (36/39, 92.3%, P &lt; 0.001), in an urban context (37/39, 94.9%, P = 0.002), taken or recently adopted from colonies (34/35, 97.1, P &lt; 0.001), with irregular or absent parasite preventive treatments (39/39, 100%, p = 0.005), without fleas (28/35, 80%, P = 0.047) and without clinical signs (22/39, 56.4%, p = 0.026) at the time of medical evaluation. Anemia was not associated with infection, but in cats without clinical signs, the percentage of anemic-infected cats (7/22, 31.8%, P = 0.009) was higher compared to non-infected cats (5/65, 7.7%). Furthermore, a decrease in total iron serum concentration approximating the lowest reference interval [median values (IQR): 79 μg/dL (52.25) vs. 50.5 μg/dL (34), P = 0.007] was likely in infected cats. No other laboratory findings were associated with infection. Interestingly, a partial/total outdoor lifestyle was a risk factor for infection (OR: 8.58, 95% CI: 2.90–37.0, P &lt; 0.001). In conclusion, the present study revealed that Cytauxzoon spp. infection manifests itself prevalently as a subclinical infection, based on physical examination and laboratory findings, in domestic European cats. However, subclinical infected cats were more likely to be anemic compared to non-infected.

Vector-borne and other pathogens of potential relevance disseminated by relocated cats

Large populations of unowned cats constitute an animal welfare, ecological, societal and public health issue worldwide. Their relocation and homing are currently carried out in many parts of the world with the intention of relieving suffering and social problems, while contributing to ethical and humane population control in these cat populations. An understanding of an individual cat’s lifestyle and disease status by veterinary team professionals and those working with cat charities can help to prevent severe cat stress and the spread of feline pathogens, especially vector-borne pathogens, which can be overlooked in cats. In this article, we discuss the issue of relocation and homing of unowned cats from a global perspective. We also review zoonotic and non-zoonotic infectious agents of cats and give a list of practical recommendations for veterinary team professionals dealing with homing cats. Finally, we present a consensus statement consolidated at the 15th Symposium of the Companion Vector-Borne Diseases (CVBD) World Forum in 2020, ultimately to help veterinary team professionals understand the problem and the role they have in helping to prevent and manage vector-borne and other pathogens in relocated cats.

Graphical Abstract

Leishmania infantum Specific Humoral and Cellular Immune Responses in Cats and Dogs: A Comparative Cross-Sectional Study

Dogs are the main reservoir of Leishmania infantum and display different immunological patterns correlating with the progression of infection to disease. Data about feline L. infantum adaptive immune response are scant. This study aimed to compare the prevalence and immune response in cats and dogs from the same endemic area of canine leishmaniosis. Stray cats (109) and rescued dogs (59) from Córdoba (Spain) were enrolled. Data about their exposure to L. infantum were analyzed by detection of parasite DNA, measurements of Leishmania-specific interferon-γ (whole blood assay in 57 cats and 29 dogs), and antibodies (enzyme-linked immunosorbent assay and immunofluorescence antibody test). An overall L. infantum prevalence of 30.5% in dogs and 30% in cats were found according to serology and PCR tests. Prevalence was 44.8% in dogs and 35.1% in cats tested also for interferon-γ production. Dogs showed higher anti-L. infantum antibody levels compared to cats. More than one-third of cats had contact with or were infected by L. infantum and they may contribute to the endemicity of leishmaniosis in the investigated region. The immunopathogenesis of feline L. infantum infection has similarities with dogs but cats show a lower level of adaptive immune response compared to dogs.

Detection of specific antibodies against Leishmania infantum in canine serum and oral transudate using an in-house ELISA

Background

Canine leishmaniosis caused by the protozoan Leishmania infantum is a complex infection due to its variable clinical signs and laboratory findings. Therefore, a broad range of techniques is available for diagnosis. Testing for specific antibodies in serum is the most commonly used technique, although the testing of other body fluids, such as oral transudate (OT), can be an alternative as its collection is non-invasive and testing can be performed by untrained personnel. The aim of this study was to assess and compare the detection of L. infantum-specific antibodies in paired samples of serum and OT collected from apparently healthy dogs and dogs with clinical leishmaniosis using an in-house enyzme-linked immunosorbent assay (ELISA).

Methods

Serum and OT were collected from 407 dogs, which varied in breed, sex, age, lifestyle and clinical status, by many practicing veterinarians in Spain. The main geographical areas of sampling included Barcelona (n = 110), Mallorca (n = 94), Cadiz (n = 54) and Asturias (n = 47). The majority of infected dogs were apparently healthy (89.9%) while 41 presented clinical signs and/or clinicopathological abnormalities compatible with L. infantum infection and subsequently diagnosed with leishmaniosis (10.1%). An in-house ELISA was performed to quantify the anti-Leishmania antibodies in serum and OT.

Results

The L. infantum infection rate determined by the in-house ELISA was 37.1% in serum samples and 32.7% in OT samples. Serum and OT ELISA results showed a positive correlation (Spearman's correlation coefficient r_s = 0.6687, P < 0.0001). The percent agreement between the serum and OT ELISA results was 84%, while agreement according to Cohen's kappa statistic (κ) was substantial (0.66) when all samples were analyzed. The highest percent agreement (92.1%) between both tests was found in dogs from low endemicity regions and from sick dogs, with both groups presenting almost perfect agreement according to Cohen’s κ agreement test (0.84). Few seronegative dogs (n = 23) tested positive by the OT ELISA. The agreement between serum and OT went from almost perfect to moderate when the geographical distribution and clinical status were analyzed.

Conclusions

The results of this study demonstrated an almost perfect to moderate agreement between OT and serum samples tested using the in-house ELISA. These results are particularly promising in sick dogs with high antibody levels while the results seem less optimal in apparently healthy dogs with low antibody levels.

Graphical Abstract

Use of preventive measures and serological screening tools for Leishmania infantum infection in dogs from Europe

Background

There are several screening tools for detecting Leishmania infantum infection in dogs and various preventive measures to protect against it. Some studies have investigated them, but not many have described their current use. The aim of this study was to investigate which preventive measures and serological screening tools for L. infantum infection were employed from 2012 to 2018 in dogs from different endemic European countries.

Methods

A set of electronic datasheets was completed for each dog from several veterinary centres. Classification of preventive measures included: (1) repellents, (2) vaccines and (3) immunomodulators. Classification of serological tests included the: (1) direct agglutination test (DAT), (2) enzyme-linked immunosorbent assay (ELISA), (3) indirect immunofluorescence (IFI), (4) rapid tests and (5) other assays. Dogs were also classified depending on their risk of exposure and living area.

Results

Information from 3762 dogs was gathered. Preventive measures were applied in 91.5% of dogs and the most frequently used were repellents (86.2%) followed by vaccines (39.8%) and Leisguard^® (15.3%). The different types of repellents (collar and spot-on) were used similarly. A combination of a vaccine and repellents was preferred in the high-risk group while the low-risk preferred a combination of Leisguard^® and a repellent (Chi-square test: X² = 88.41, df = 10, P < 0.001). Furthermore, all preventive measures were similarly used through the years except for repellents, which were predicted to have a small increase of use each year. Regarding serological screening tools, the most used were rapid and ELISA tests. Rapid tests, ELISA tests and DAT were used similarly through the years, but a significant change was found in the use of IFI and other assays whose use decreased a little each year.

Conclusions

Repellents were the preferred measure, while vaccines and Leisguard^® were second-line options. Some dogs were not treated by any measures, which highlights the need for dog owner education. Moreover, there seems to be a preference for rapid tests in the clinical setting to detect specific L. infantum antibodies while ELISA or IFI are less often employed. This underlines an increasing problem, as qualitative rapid tests have a variable diagnostic performance limiting the adequate diagnosis of seropositive dogs in endemic areas.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05251-5.

Association between feline immunodeficiency virus and Leishmania infantum infections in cats: a retrospective matched case-control study

BACKGROUND

Feline leishmaniosis caused by Leishmania infantum is often associated with feline immunodeficiency virus (FIV) infection; however, the role and clinical significance of this coinfection remain unknown. This study aimed to assess whether FIV is associated with L. infantum infection in cats from canine leishmaniosis endemic areas and to report the clinical signs and hematological alterations associated with coinfection.

METHODS

A retrospective matched case-control study (ratio 1:2) was conducted. Data of clinical examination and complete blood count (CBC) were selected from a cohort of 705 cats examined for epidemiological studies on feline leishmaniosis conducted between 2012 and 2019. Ninety-one FIV seropositive cases and 182 FIV seronegative control cats were selected. Matching was done according to age, sex, lifestyle and geographic provenience of case cats. Rapid ELISA devices were mainly used to detect anti-FIV antibodies. Anti-Leishmania IgG antibodies were detected by indirect-immunofluorescence test (IFAT). Leishmania DNA was searched in blood, oral and conjunctival swabs by quantitative real-time PCR.

RESULTS

Feline immunodeficiency virus seropositive cats had no hematological abnormalities suggestive of an advanced stage of FIV infection and were statistically more frequently IFAT positive, and their risk of being L. infantum antibody positive was 2.8 greater than in the FIV seronegatives. The association of FIV seropositivity with L. infantum antibody positivity was confirmed in the univariable model of logistic regression. A multivariate model found FIV infection and L. infantum PCR positivity as predictors of a positive L. infantum IFAT result. Male outdoor cats from rural or suburban areas were at risk for FIV and L. infantum antibody positivity. Clinical signs more frequently associated with the coinfection were oral lesions, pale mucous membranes and low body condition score (BCS).

CONCLUSIONS

This study documents that FIV seropositive cats with no hematological abnormalities suggestive of an advanced stage of FIV infection are more prone to be L. infantum seroreactive by IFAT in endemic areas. Therefore, FIV seropositive cats should be tested for L. infantum antibodies and treated for preventing sand fly bites. Pale mucous membranes, low BCS and oral lesions but no CBC abnormalities were significantly associated with the coinfection.

Prospective serological and molecular cross-sectional study focusing on Bartonella and other blood-borne organisms in cats from Catalonia (Spain)

Background

There is limited clinical or epidemiological knowledge regarding Bartonella infection in cats, and no serological studies have compared the presence of antibodies against different Bartonella species. Moreover, there are limited feline Bartonella studies investigating co-infections with other vector-borne pathogens and the associated risk factors. Therefore, the objective of this study was to investigate Bartonella spp. infections and co-infections with other pathogens in cats from Barcelona (Spain) based on serological and/or molecular techniques and to determine associated risk factors.

Methods

We studied colony and owned cats (n = 135). Sera were tested for Bartonella henselae-, Bartonella quintana-, and Bartonella koehlerae-specific antibodies using endpoint in-house immunofluorescence antibody assays. Bartonella real-time PCR (qPCR) and conventional PCR (cPCR) were performed. In addition, cPCR followed by DNA sequencing was performed for other pathogenic organisms (Anaplasma, Babesia, Cytauxzoon, Ehrlichia, Hepatozoon, hemotropic Mycoplasma, and Theileria spp.).

Results

From 135 cats studied, 80.7% were seroreactive against at least one Bartonella species. Bartonella quintana, B. koehlerae, and B. henselae seroreactivity was 67.4, 77.0, and 80.7%, respectively. Substantial to almost perfect serological agreement was found between the three Bartonella species. Colony cats were more likely to be Bartonella spp.-seroreactive than owned cats. Moreover, cats aged ≤ 2 years were more likely to be Bartonella spp.-seroreactive. Bartonella spp. DNA was detected in the blood of 11.9% (n = 16) of cats. Cats were infected with B. henselae (n = 12), B. clarridgeiae (n = 3), and B. koehlerae (n = 1). Mycoplasma spp. DNA was amplified from 14% (n = 19) of cat blood specimens. Cats were infected with Mycoplasma haemofelis (n = 8), Candidatus M. haemominutum (n = 6), Candidatus Mycoplasma turicensis (n = 4), and Mycoplasma wenyonii (n = 1). Anaplasma, Babesia, Cytauxzoon, Ehrlichia spp., Hepatozoon, and Theileria spp. DNA was not amplified from any blood sample. Of the 16 Bartonella spp.-infected cats based on PCR results, six (37%) were co-infected with Mycoplasma spp.

Conclusions

Bartonella spp. and hemoplasma infections are prevalent in cats from the Barcelona area, whereas infection with Anaplasma spp., Babesia, Cytauxzoon, Ehrlichia spp., Hepatozoon, and Theileria infections were not detected. Co-infection with hemotropic Mycoplasma appears to be common in Bartonella-infected cats. To our knowledge, this study is the first to document M. wenyonii is infection in cats.

Graphical Abstract

Is signalment associated with clinicopathological findings in dogs with leishmaniosis?

BACKGROUND

Canine leishmaniosis (CanL) is a common infectious disease. Age, sex and breed might influence the type of clinical and pathological manifestations that dogs develop. The main objective of this retrospective cross-sectional study was to determine if an association between age, sex, breed and size and the clinical findings of CanL exists.

MATERIAL AND METHODS

Dogs with a diagnosis of leishmaniosis were enrolled (n = 123). Clinical information, including signalment, clinical signs and laboratory abnormalities, was retrieved from medical records from different veterinary facilities from Catalonia.

RESULTS

Young dogs developed less frequently systemic signs (p = 0.0046), renal (p = 0.0019) and haematologic (p = 0.0275) abnormalities, while dermatologic signs were more common in young and adult dogs compared with old ones (p = 0.0451). Young dogs showed proteinuria less often than adult and old dogs (p = 0.0029). Young dogs did not present renal azotemia, while old dogs showed occasionally renal azotemia (p = 0.0478). Young dogs were mainly classified as mild-moderate LeishVet clinical stages of the disease, and very rarely as severe-very severe LeishVet clinical stages, compared with adult and old dogs (p = 0.0457). Purebred dogs significantly developed ulcerative dermatitis more frequently than crossbred dogs (p = 0.0460).

CONCLUSION

This study describes that age is associated with differences in clinicopathological findings of CanL.

Ménétrier-like disease in a Pointer with concurrent granulomatous gastritis, helicobacteriosis and leishmaniosis: a case report

Background

Ménétrier-like disease is a rare hypertrophic canine gastropathy, reported in only seven dogs. Clinical signs are vomiting, anorexia and weight loss. Macroscopically, giant cerebriform gastric mucosal folds are typically seen in the corpus and fundus of the stomach. Histopathologically, fundic mucous cell hyperplasia and loss of parietal and chief cells are typical.

Case presentation

A nine-year-old spayed female Pointer had a history of intermittent vomiting, marked weight loss and hypoalbuminaemia. A gastroduodenoscopy was performed three times within three months with macroscopic changes remaining the same. The gastric mucosa of the corpus, fundus and proximal antrum was markedly irregular, with cerebriform mucosal folds. In the first gastric biopsies, histopathology revealed a moderate granulomatous gastritis, with a severe manifestation of Helicobacter-like organisms. Treatment for Helicobacter spp. decreased the vomiting slightly. The dog was diagnosed with concurrent leishmaniosis; the conventional anti-Leishmania treatment decreased the vomiting moderately, the hypoalbuminaemia resolved and the dog gained weight back to a normal body condition. Granulomatous gastritis was not present in the gastric biopsies after these treatments. The dog increased vomiting when palliative treatment (maropitant citrate, ondansetron and esomeprazole) was discontinued, and thus, full-thickness biopsies of the stomach were taken and Ménétrier-like disease was diagnosed. The affected area was too large to be surgically removed; thus, palliative treatment was reinstated. The dog remained clinically well 39 months after the first clinical presentation.

Conclusions

This is the first report of Ménétrier-like disease in a dog with a simultaneous manifestation of granulomatous gastritis, helicobacteriosis and leishmaniosis. The clinical signs decreased after treatment of helicobacteriosis and leishmaniosis, but vomiting remained probably as a sign of Ménétrier-like disease. Treatment options for dogs are surgical removal of the abnormal area or palliative treatment. In humans, promising results for a cure have been shown with cetuximab treatment, a human monoclonal antibody, but no canine antibody is commercially available yet. The dog here was doing well 39 months after first presentation, which is the longest reported survival time for Ménétrier-like disease with only palliative treatment in dogs. Full-thickness biopsies are preferred in macroscopic hypertrophic lesions of the stomach for better assessment of Ménétrier-like disease.

The Effects of Polyhexamethylene Biguanide (PHMB) and TLR Agonists Alone or as Polyplex Nanoparticles against Leishmania infantum Promastigotes and Amastigotes

Dogs are the main reservoir for Leishmania infantum, manifesting from a subclinical to a fatal disease. Limited treatments are available, although new antiparasitics and immunomodulators are pursued. Polyhexamethylene biguanide (PHMB) has a broad antimicrobial spectrum, including antiparasitic activity. Here, we evaluated the potential for Toll-like receptor agonists (TLRa) and PHMB alone, and as polyplex nanoparticles containing PHMB and TLR4 or TLR9 agonists, to selectively kill L. infantum. Susceptibility of L. infantum promastigotes to PHMB, miltefosine, and allopurinol was performed, and the half-maximum inhibitory concentrations (IC₅₀) were determined. Then, DH-82 cells were infected and treated with PHMB alone or combined with TLR4a (MPLA-SM) or TLR9a (CpG ODNs) and allopurinol alone. The IC₅₀ values of L. infantum promastigotes were PHMB (1.495 µM), miltefosine (9.455 µM), and allopurinol (0.124 µM). After infection, treated DH-82 cells displayed a lower percentage (p = 0.0316), intensity (p = 0.0002), and index of infection (p = 0.0022) when compared to non-treated cells. PHMB induced lower percentage of infection alone (p = 0.043), in combination with TLR9a (p = 0.043), and with TLR4a (p = 0.0213). Supernatants were collected and used to measure TNF-α and IL-6 levels. Increased TNF-α was observed after PHMB plus TLR4a, relative to uninfected and infected untreated macrophages (p = 0.043). PHMB combined with TLR4a shows promise as a potential anti-L. infantum drug combination, as well as inducer of proinflammatory response, as demonstrated by decreased infection and increased TNF-α production.

Parasites and vector-borne diseases disseminated by rehomed dogs

The Companion Vector-Borne Diseases (CVBD) World Forum is a working group of leading international experts who meet annually to evaluate current scientific findings and future trends concerning the distribution, pathogenesis, clinical presentation, diagnosis and prevention of vector-borne infections of dogs and cats. At the 14th Symposium of the CVBD World Forum in Trieste, Italy (March 25-28, 2019), we identified the need to (i) bring attention to the potential spread of parasites and vectors with relocated dogs, and (ii) provide advice to the veterinary profession regarding the importance of surveillance and treatment for parasites and vector-borne infections when rehoming dogs. This letter shares a consensus statement from the CVBD World Forum as well as a summary of the problem faced, including the role of veterinary professionals in parasite surveillance, causal issues, and the importance of interdisciplinary cooperation in addressing the problem. To limit opportunities for dissemination of parasites and vectors, whenever possible, underlying problems creating the need for dog rehoming should be addressed. However, when it is necessary to rehome dogs, this should ideally take place in the country and national region of origin. When geographically distant relocation occurs, veterinary professionals have a vital role to play in public education, vigilance for detection of exotic vectors and infections, and alerting the medical community to the risk(s) for pathogen spread. With appropriate veterinary intervention, dog welfare needs can be met without inadvertently allowing global spread of parasites and their vectors.

Seroprevalence Rates of Tick-Borne Pathogens in Cats from Southern Bulgaria

The aim of the present study was to investigate the prevalence rates of the feline tick-borne pathogens (FTBPs)-Borrelia burgdorferi, Ehrlichia canis, and Anaplasma phagocytophilum in stray cats from Southern Bulgaria. Serum antibodies were used to estimate the prevalence of exposure to FTBPs from blood swabs. Of the 100 cat samples tested with in-clinic assay SNAP 4Dx Plus, the overall FTBP seroprevalence was 3% (3/100); with B. burgdorferi-1% (1/100) and E. canis-2% (2/100). This study provides the first evidence of exposure to B. burgdorferi and E. canis in cats from Bulgaria.

Serological and molecular survey of Leishmania infection in dogs from Venezuela

Venezuela is a country where human and canine leishmaniosis due to Leishmania infantum, Leishmania braziliensis and other Leishmania spp. is endemic. However, only limited data is available on canine Leishmania infection in Venezuela. The aim of this cross-sectional study was to evaluate the prevalence of Leishmania infection in dogs (n = 152) from the states of Lara (n = 91) and Yaracuy (n = 61) in Venezuela by means of serological and molecular methods. Physical examination was performed and blood samples were collected from all dogs. Serology for antibodies reactive with L. infantum and L. braziliensis antigens was assessed by the enzyme-linked immunosorbent assay (ELISA) and detection of Leishmania DNA from blood samples was evaluated by kinetoplast Leishmania real-time polymerase chain reaction (RT-PCR). In addition, Leishmania internal transcribed spacer (ITS-1) RT-PCR was performed on the samples positive by kinetoplast RT-PCR. The prevalence of Leishmania infection based on serological and/or molecular techniques was 11.8%. The seroprevalence for L. infantum and L. braziliensis antigens were 2.1% (3/144) and 8.3% (12/144), respectively. All dogs from the state of Yaracuy were serologically negative to L. infantum while 4.6% (4/86) of the dogs were reactive to L. braziliensis antigen. Fourteen percent (8/58) of the dogs from the state of Lara were positive to L. infantum and 5.2% (3/58) to L. braziliensis antigen. Three dogs were positive to both Leishmania spp. antigens. By RT-PCR, 6.5% (4/61) and 4.4% (4/91) of the dogs were positive for infection in the states of Lara and Yaracuy, respectively. The RT-PCR product of one dog from the state of Yaracuy was sequenced revealing a 100% identity with L. infantum. However, all RT-PCR positive dogs were seronegative to both Leishmania spp. antigens. In conclusion, the positivity for Leishmania spp. infections observed indicates that dogs are frequently infected by L. infantum, L. braziliensis or related Leishmania spp. in Venezuela.

Exploring the relationship between susceptibility to canine leishmaniosis and anti-Phlebotomus perniciosus saliva antibodies in Ibizan hounds and dogs of other breeds in Mallorca, Spain

Background

Canine leishmaniosis caused by Leishmania infantum is a neglected zoonosis transmitted by sand flies like Phlebotomus perniciosus. Clinical signs and disease susceptibility vary according to various factors, including host immune response and breed. In particular, Ibizan hounds appear more resistant. This immunocompetence could be attributed to a more frequent exposure to uninfected sand flies, eliciting a stronger anti-sand fly saliva antibody response.

Methods

This study aimed to investigate the prevalence of anti-P. perniciosus saliva antibodies in Ibizan hounds and dogs of other breeds in the Leishmania-endemic area of Mallorca, Spain, and to correlate these antibody levels with clinical, immunological and parasitological parameters. Anti-sand fly saliva IgG was examined in 47 Ibizan hounds and 45 dogs of other breeds using three methods: P. perniciosus whole salivary gland homogenate (SGH) ELISA; recombinant protein rSP03B ELISA; and rSP03B rapid tests (RT). Additionally, diagnostic performance was evaluated between methods.

Results

Results indicate significantly higher anti-SGH antibodies (P = 0.0061) and a trend for more positive SGH ELISA and RT results in Ibizan hounds compared to other breeds. General linear model analysis also found breed to be a significant factor in SGH ELISA units and a marginally significant factor in RT result. Although infection rates were similar between groups, Ibizan hounds included significantly more IFN-γ producers (P = 0.0122) and papular dermatitis cases (P < 0.0001). Older age and L. infantum seropositivity were also considered significant factors in sand fly saliva antibody levels according to at least one test. Fair agreement was found between all three tests, with the highest value between SGH and rSP03B RT.

Conclusions

To our knowledge, this is the first study elaborating the relationship between anti-P. perniciosus saliva antibodies and extensive clinical data in dogs in an endemic area. Our results suggest that Ibizan hounds experience a higher frequency of exposure to sand flies and have a stronger cellular immune response to L. infantum infection than other breed dogs. Additional sampling is needed to confirm results, but anti-P. perniciosus saliva antibodies appear to negatively correlate with susceptibility to L. infantum infection and could possibly contribute to the resistance observed in Ibizan hounds.

Canine Leishmaniasis Control in the Context of One Health

Dogs are the main reservoir of Leishmania infantum and in some countries have been regularly culled as part of government policy to control visceral leishmaniasis. At the 13th Symposium of the Companion Vector-Borne Diseases World Forum in Windsor, UK, March 19–22, 2018, we consolidated a consensus statement regarding the usefulness of dog culling as a means of controlling visceral leishmaniasis. The statement highlighted the futility of culling infected dogs, whether healthy or sick, as a measure to control the domestic reservoir of L. infantum and reduce the risk for visceral leishmaniasis.

Vaccination against canine leishmaniasis in Brazil

Prevention of canine Leishmania infantum infection is critical to management of visceral leishmaniasis in people living in endemic areas of Brazil. A bill (PL 1738/11), currently under consideration, proposes to establish a national vaccination policy against canine leishmaniasis in Brazil. However, there is no solid scientific evidence supporting the idea that this could reduce transmission from infected vaccinated dogs to sand flies to a level that would significantly reduce the risk of L. infantum infection or visceral leishmaniasis in humans. Thus, we advocate that insecticide-impregnated collars should the first line protective measure for public health purposes and that vaccines are applied on a case-by-case, optional basis for individual dog protection.

Toll-like receptors 2, 4 and 7, interferon-gamma and interleukin 10, and programmed death ligand 1 transcripts in skin from dogs of different clinical stages of leishmaniosis

Background

Canine leishmaniosis (CanL) caused by Leishmania infantum can have several dermatological manifestations. The type of immune response elicited against the parasite appears to be at the basis for such clinical variability. Much of the work in CanL has focused on adaptive immune response and there are scarce data on the importance of the innate immune responses. Moreover, few studies have evaluated the immunological response in the cutaneous lesions in dogs naturally infected with L. infantum and with different degrees of disease severity, and no study has compared clinically-lesioned with normal-looking skin.

Methods

We determined and compared the transcription of toll like receptors (TLRs) 2, 4 and 7, interferon gamma (IFN-γ), interleukin (IL) 10 and programmed cell death protein ligand (PD-L) 1 by real-time PCR in paired clinically-lesioned and normal-looking skin from 25 diseased dogs (mild disease-stage I (n = 11) and moderate to severe disease-stages II and III (n = 14) as well as in normal-looking skin from healthy dogs (n = 10) from a non-endemic area. We also assessed the association between the transcripts in clinically-lesioned and normal-looking skin of dogs with leishmaniosis with clinicopathological, immunological and parasitological findings.

Results

Clinically-lesioned skin from mildly affected dogs was characterized by a significant upregulation of TLR2 (P < 0.0001) and IL-10 (P = 0.021) and downregulation of TLR7 (P = 0.004) when compared with more severely affected dogs. Normal-looking skin of mildly affected dogs was characterized by a significant lower expression of TLR7 (P = 0.003), IFN-γ (P < 0.0001) and PD-L1 (P = 0.001) when compared with more severely affected dogs. TLR2, TLR4, IL-10 and IFN-γ upregulation in clinically-lesioned skin was correlated with lower disease severity while TLR7 upregulation was correlated with markers of disease severity. Upregulation of TLR7, IL-10, IFN-γ and PD-L1 in normal-looking skin was correlated with disease severity.

Conclusions

This study demonstrated different expression profiles of immune genes in clinically-lesioned and normal-looking skin among mildly and more severely affected dogs. These immunological conditions might favor the maintenance and replication of the parasite in the skin of more severely affected dogs.

Associations between clinical canine leishmaniosis and multiple vector-borne co-infections: a case-control serological study

BACKGROUND

Dogs that have clinical leishmaniosis (ClinL), caused by the parasite Leishmania infantum, are commonly co-infected with other pathogens, especially vector-borne pathogens (VBP). A recent PCR-based study found that ClinL dogs are more likely to be additionally infected with the rickettsial bacteria Ehrlichia canis. Further information on co-infections in ClinL cases with VBP, as assessed by serology, is required. The research described in this report determined if dogs with ClinL are at higher risk of exposure to VBP than healthy control dogs using a case-control serology study.

RESULTS

Of the 47 dogs with ClinL, anti-E. canis/ Ehrlichia ewingii antibodies were detected in 17 (36.2%), anti-Anaplasma phagocytophilum/Anaplasma platys antibodies in 5 (10.6%) and antigen for Dirofilaria immitis in 2 (4.3%). Of the 87 control dogs, anti-E. canis/E. ewingii antibodies were detected in 14 (16.1%) and anti-A. phagocytophilum/A. platys antibodies in 2 (2.3%). No anti-Borrelia burgdorferi antibody tests were positive. No statistical differences between the ClinL dogs and control dogs regarding lifestyle or use of ectoparasitic prevention, were identified. The ClinL was significantly associated with anti-E. canis/E. ewingii antibodies (odds ratio = 2.9, 95% confidence interval: 1.3-6.7, P = 0.010) compared to controls by both multivariable logistic regression and structural equation modelling.

CONCLUSIONS

It was demonstrated that an increased risk for E. canis/E. ewingii seropositivity is present in dogs with ClinL compared to clinically healthy control dogs, despite similar ectoparasitic prevention use and lifestyle. Based on these findings it is suggested that dogs with ClinL should not only be tested for E. canis co-infection using PCR but also serologically for E. canis/E. ewingii.

Diagnostic performance of a qPCR for Leishmania on stained cytological specimens and on filter paper impressions obtained from cutaneous lesions suggestive of canine leishmaniosis

BACKGROUND

Detection of Leishmania in cutaneous lesions is possible by visualization of amastigotes. Detection of Leishmania DNA by PCR presents greater sensitivity, and PCR has been used to diagnose cutaneous leishmaniosis in humans using noninvasive clinical specimens.

OBJECTIVES

Study I: to determine if Leishmania DNA could be efficiently extracted and amplified from archived Diff-Quik^® -stained slides of cytological specimens from canine cutaneous lesions. Study II: to evaluate the diagnostic performance of a Leishmania-quantitative (q)PCR on stained cytological specimens and on filter paper impressions (FPI) obtained from cutaneous lesions suggestive of canine leishmaniosis (CanL).

ANIMALS

Samples from cutaneous lesions of 54 dogs.

METHODS AND MATERIALS

Study I: Leishmania-qPCR was performed on 19 glass slides (from nine dogs) with cytologically visible amastigotes. Fifteen slides with no visible amastigotes, obtained from 12 dogs seronegative for Leishmania by ELISA, served as controls. Study II: Leishmania-qPCR was performed on glass slides and FPI from cutaneous lesions compatible with clinical leishmaniosis in 33 dogs.

RESULTS

Study I: all slides with visible amastigotes had positive qPCR, whereas all control slides yielded negative results. Study II: of 13 dogs definitively diagnosed with clinical leishmaniosis, eight had visible amastigotes on cytology, whereas Leishmania-qPCR was positive on 11 glass slides and 13 FPI. Leishmaniosis was ruled out by standard methods in 20 dogs, four of which yielded positive qPCR on FPI and/or glass slides.

CONCLUSIONS AND CLINICAL IMPORTANCE

Leishmania-DNA can be detected efficiently by qPCR from cutaneous cytological specimens and FPI to diagnose Leishmania infection in dogs with cutaneous lesions suggestive of CanL.

An investigation of polymorphisms in innate and adaptive immune response genes in canine leishmaniosis

The outcome of infection with Leishmania infantum in dogs is variable, which is thought to be due to the nature of the immune response mounted by the host. As a consequence, the clinical signs and severity of canine leishmaniosis vary between individual dogs. Host immunogenetic factors might play an important role in determining the outcome of infection. The aim of this study was to examine polymorphisms in innate and adaptive immune response genes, to determine whether any of these were associated with susceptibility or resistance to L. infantum infection. Genomic DNA was obtained from two groups: pet dogs in endemic regions of Europe and a group of Beagles exposed to sand fly infection as part of a vaccine study. Genotyping was performed using a SNP (single nucleotide polymorphism) array for selected immune response genes. The first part of the study compared 62 clinical cases with 101 clinically unaffected dogs that were seronegative for Leishmania antibodies. One SNP in the CIITA gene demonstrated a significantly higher minor allele frequency in the case group, compared with the control group at the individual SNP level after permutation, but was not significant after correction for multiple testing. The second part of the study examined 48 Beagle dogs exposed to L. infantum over two transmission seasons. Twenty-seven dogs with a resistant phenotype (no evidence of clinical disease, seronegative at the end of the study period, negative on lymph node culture and only transiently PCR positive in bone marrow) were compared with 21 dogs demonstrating a susceptible phenotype (clinical disease, seropositive, positive lymph node culture and consistently PCR positive in bone marrow). Three SNPs in TLR3, two SNPs in PTPN22 and one SNP in TLR4 and IL1A were associated with the susceptible phenotype in the Beagle group at the individual SNP level after permutation analysis, but were not significant after correction for multiple testing. Further validation of these SNPs is required in a larger cohort of dogs, ideally with extreme phenotypes to confirm an association with the outcome of L. infantum infection.

Total serum IgD from healthy and sick dogs with leishmaniosis

Background

Canine leishmaniosis (CanL) due to Leishmania infantum is characterized by the development of both cellular and humoral immune responses. The dysfunction of T cell-mediated immunity leads to a lack of proliferation of T cells in response to Leishmania antigens with the consequence of parasite dissemination that seems to be related to a T cell exhaustion mediated by regulatory B cells expressing immunoglobulin D (IgD). The aim of this study was to determine and compare the total serum IgD in dogs with clinical leishmaniosis and in clinically healthy dogs.

Results

A total of 147 dog sera were studied. All dogs were tested for L. infantum-specific antibodies by quantitative ELISA. Interferon-gamma (IFN-γ) production was also determined by sandwich ELISA after blood stimulation with L. infantum soluble antigen (LSA) or concanavalin A (ConA). The quantification of total IgD was performed using a human IgD sandwich ELISA quantification set. Dogs were classified in three different groups. Group 1 included 40 clinically healthy non-infected dogs, all serologically negative to L. infantum-specific antibodies and non-producers of IFN-γ upon LSA stimulation. Group 2 included 63 clinically healthy infected dogs that were LSA IFN-γ producers (n = 61) and/or IFN-γ non-producers (n = 2) as well as negative to medium seropositive to L. infantum antigen. Finally, Group 3 included 44 dogs with clinical leishmaniosis (IFN-γ producers, n = 23; and IFN-γ non-producers, n = 21) that were negative to highly positive to L. infantum-specific antibodies. No significant differences were observed when the total IgD concentration was compared within groups. Additionally, total IgD of sick IFN-γ producers and IFN-γ non-producers was not significantly different. Finally, total IgD concentration was not statistically related to demographic parameters such as age, sex and breed.

Conclusions

The results of this study demonstrated that there were no differences between groups in total serum IgD. Total serum IgD does not appear to be a marker of disease in CanL.

Leishmania infantum-specific IFN-γ production in stimulated blood from cats living in areas where canine leishmaniosis is endemic

Background

Feline leishmaniosis caused by Leishmania infantum is considered a rare disease in endemic areas, whereas subclinical infections are common. Immune response plays a key role in driving the course of L. infantum infection in other host species; however, the feline cell-mediated immune response to L. infantum infection has not yet been investigated. The aim of this study was to determine the cell-mediated immune response specific to L. infantum by means of interferon (IFN)-γ release in whole blood assay from cats living in endemic areas (66 in Sicily and 113 in Catalonia) and to compare with antibody levels to L. infantum [enzyme-linked immunosorbent assay (ELISA) and immunofluorescence antibody test (IFAT)], blood parasite load and retroviral infections.

Results

Most cats (n = 140) were L. infantum antibody negative and only 22% (n = 39) were positive. Only 9 and 2% of tested cats had a feline immunodeficency virus (FIV) infection or a feline leukemia virus (FeLV) infection, respectively. Thirty-two cats out of 179 (18%) produced IFN-γ after stimulation with L. infantum soluble antigen (LSA) while the majority of cats (93%) produced IFN-γ after stimulation with concanavalin A (ConA). Six LSA-IFN-γ-producer cats were seropositive (three to ELISA and five to IFAT) but they were polymerase chain reaction (PCR) negative, while only one cat was antibody- and PCR-positive. Significant positive correlations were found between IFN-γ concentrations after stimulation with LSA and ConA, and between serology and PCR testing. No association was found between FIV status and LSA or ConA-IFN-γ production. Combining PCR, serology and specific IFN-γ concentration results, we found that 36% of cats studied were exposed to L. infantum.

Conclusions

As expected, cats from endemic areas produce IFN-γ after ex vivo blood stimulation with LSA and therefore are able to activate a cell-mediated adaptive immune response against the parasite that is variably associated with antibody or blood PCR positivity. The association of this assay to serological and molecular tests provides a better estimate of cat exposure to L. infantum.

Hypercalcemia of Malignancy in a Dog Diagnosed With Cholangiocellular Carcinoma

A 4-year-old, neutered male Golden Retriever was presented with a 1-week history of weight loss, polyuria, and polydipsia. The diagnostic workup showed an increased ionized calcium concentration, mild increase in serum creatinine and urea concentration, and severe hyperlipasemia. A complete abdominal ultrasound revealed multiple hepatic nodules. A cytological diagnosis of malignant epithelial neoplasia, highly suggestive of bile duct adenocarcinoma was made. In order to confirm the presumptive diagnosis of hypercalcemia of malignancy due to the presence of a hepatic neoplasia, serum parathormone-related peptide concentration was measured, and the result revealed an increased concentration. The dog was hospitalized and received supportive treatments consisting of intravenous furosemide and fluid therapy. After ruling out lymphoma and hypoadrenocorticism, oral prednisone was initiated and ionized calcium concentration decreased gradually down to normal concentration after 7 days of hospitalization. Chemotherapy with intravenous epirubicin was initiated based on the cytological diagnosis. One month after diagnosis and due to the worsening of its clinical condition, the dog was humanely euthanized. Postmortem examination confirmed a cholangiocellular carcinoma. To our knowledge, this is the first report of malignant hypercalcemia associated with cholangiocellular carcinoma in a dog.

Detection of Leishmania spp. Infection by Immunohistochemistry in Archived Biopsy Samples from Dogs with Colitis in an Area Endemic for Leishmaniosis

Previous studies have demonstrated the presence of Leishmania infantum amastigotes in the colonic mucosa of seropositive sick dogs. However, there are no studies that have investigated the presence of L. infantum infection in dogs diagnosed with inflammatory bowel disease (IBD). The aims of this study were: (1) to investigate retrospectively the presence of Leishmania spp. antigen by immunohistochemistry (IHC) in biopsy samples taken from the colon of dogs with IBD in an area endemic for leishmaniosis, and (2) to describe the main histopathological findings in these cases. Clinicopathological data and histopathological results were reviewed from 106 cases of canine colitis. IHC to detect Leishmania spp. antigen had been performed at the time of diagnosis in 13 cases and we performed IHC in 56 more cases. Five of the 69 cases (7.2%) were positive for Leishmania spp. antigen by IHC. Two positive biopsy samples had histiocytic inflammation and three had lymphoplasmacytic inflammation. The number of amastigotes was variable and independent of the type and grade of inflammatory infiltrate. The results suggest that Leishmania spp. infection is associated with chronic colitis in areas endemic for the infection. Therefore, Leishmania IHC should be used routinely as a diagnostic tool when evaluating colonic biopsy samples from dogs in endemic areas, to exclude or confirm an infection by this parasite in dogs with chronic colitis.

Bartonella infections in cats and dogs including zoonotic aspects

Bartonellosis is a vector-borne zoonotic disease with worldwide distribution that can infect humans and a large number of mammals including small companion animals (cats and dogs). In recent years, an increasing number of studies from around the world have reported Bartonella infections, although publications have predominantly focused on the North American perspective. Currently, clinico-pathological data from Europe are more limited, suggesting that bartonellosis may be an infrequent or underdiagnosed infectious disease in cats and dogs. Research is needed to confirm or exclude Bartonella infection as a cause of a spectrum of feline and canine diseases. Bartonella spp. can cause acute or chronic infections in cats, dogs and humans. On a comparative medical basis, different clinical manifestations, such as periods of intermittent fever, granulomatous inflammation involving the heart, liver, lymph nodes and other tissues, endocarditis, bacillary angiomatosis, peliosis hepatis, uveitis and vasoproliferative tumors have been reported in cats, dogs and humans. The purpose of this review is to provide an update and European perspective on Bartonella infections in cats and dogs, including clinical, diagnostic, epidemiological, pathological, treatment and zoonotic aspects.

Hepatozoon canis in three imported dogs: a new tickborne disease reaching the United Kingdom

An increasing number of non-endemic vectorborne pathogens have been described in dogs imported to the UK in the past two decades. Recently, an outbreak of canine babesiosis in south-east England has raised veterinary awareness with regard to the impact of such diseases on the UK canine population. Canine hepatozoonosis, caused by Hepatozoon canis and transmitted by the ingestion of Rhipicephalus sanguineus ticks, is widespread in the Mediterranean basin. Herein we describe the first three molecularly confirmed clinical cases of canine hepatozoonosis in dogs imported into the UK. Veterinarians in the UK should be aware of H canis as a potential infection in imported dogs, especially in the face of the expanding distribution of R sanguineus ticks in Europe.

Use of acute phase proteins for the clinical assessment and management of canine leishmaniosis: general recommendations

BACKGROUND

Dogs with canine leishmaniosis (CanL) due to Leishmania infantum can show a wide spectrum of clinical and clinicopathological findings at the time of diagnosis. The aim of this paper is to describe the possible application of acute phase proteins (APPs) for the characterization and management of this disease, based on previously published information on the utility of APPs in CanL and the experience of the authors in using APPs as analytes in the profiling of canine diseases.

MAIN BODY

Dogs diagnosed with L. infantum infection by serology, polymerase chain reaction, cytological or histopathological identification, can be divided into three groups based on their clinical condition at physical examination and their APPs concentrations: Group 1: dogs with no clinical signs on physical examination and APPs in reference range; Group 2: dogs with changes in APPs but no clinical signs on physical examination; Group 3: dogs with clinical signs and changes in APPs. This report describes the main characteristics of each group as well as its association with the clinical classification schemes of CanL.

CONCLUSION

APPs concentration can be a useful clinical tool to characterize and manage CanL.

Inconsistent MHC class II association in Beagles experimentally infected with Leishmania infantum

The clinical outcome of Leishmania infantum infection in dogs varies from subclinical infection to severe disease. Researchers attribute this variability in clinical manifestations to the ability of the immune response to limit pathogen multiplication and dissemination, which is, in part, likely determined by the immune response genes. The aim of this study was to test the hypothesis that MHC class II genes are associated with disease outcome of experimental L. infantum infection in Beagles. Dog leukocyte antigen (DLA) class II haplotypes were characterised by sequence-based typing of Beagle dogs experimentally infected with L. infantum during vaccine challenge studies. Variability of response to infection was determined by clinical score, serology and quantification of L. infantum DNA in the bone marrow over the study period. Dogs showed limited DLA diversity and the DLA profiles of dogs recruited for the different vaccine challenge studies differed. There were variable responses to infection, despite the apparent restriction in genetic diversity. One haplotype DLA-DRB1*001:02-DQA1*001:01-DQB1*002:01 was associated with increased anti-Leishmania antibodies in one infection model, but no DLA associations were found in other groups or with parasite load or clinical score. Examination of this particular DLA haplotype in a larger number of dogs is required to confirm whether an association exists with the immune or clinical responses to L. infantum infection.

Clinical evaluation of outdoor cats exposed to ectoparasites and associated risk for vector-borne infections in southern Italy

BACKGROUND

Cats can be carriers of infected arthropods and be infected with several vector-borne pathogens (VBP) but there is limited knowledge about their pathogenic role in cats.

RESULTS

A cross-sectional controlled study investigated the clinical status and antibody (Bartonella henselae, Rickettsia conorii, Ehrlichia canis, Anaplasma phagocytophilum, Babesia microti and Leishmania infantum) and/or blood PCR (Mycoplasma spp., Bartonella spp., Rickettsia spp., Ehrlichia/Anaplasma spp., piroplasmids, L. infantum, Hepatozoon felis) prevalence in 197 cats. Outdoor cats lacking ectoparasiticide treatment or hosting ectoparasites (study group [SG], n = 134) and indoor cats treated against ectoparasites (control group [CG], n = 63) were enrolled. Clinical data and retroviral co-infections were compared between the two groups. Multivariable analysis tested associations between variables and VBP exposure. Lymphadenia, stomatitis, and various haematological abnormalities were statistically more frequent in SG. Antibodies against R. conorii, B. henselae, A. phagocytophylum, B. microti, E. canis and L. infantum were detected. Bartonella henselae, Bartonella clarridgeiae, Mycoplasma haemofelis, "Candidatus Mycoplasma haemominutum" and "Candidatus Mycoplasma turicensis" DNA were identified. Very high antibody (87.8%) and PCR (40.1%) positivity to at least one pathogen were detected and were significantly higher in SG. Co-infections were confirmed in about one-third of the cats and were more frequent in SG cats. Molecular and overall (antibody and PCR) positivity to Bartonella and antibody positivity to R. conorii were higher in SG. Multivariable analysis found significant associations of Bartonella spp. infection with Feline Immunodeficiency Virus (FIV) infection and increased globulins, and of Mycoplasma spp. infection with adult age, FIV infection, anaemia, and increased creatinine.

CONCLUSIONS

A very high prevalence of exposure to zoonotic VBP was found in cats, with Rickettsia and Bartonella infections being most prevalent. Some risk factors were documented namely for Mycoplasma spp. and Bartonella spp. The lifestyle of cats is clinically relevant and requires specific preventative measures to protect their health.

Association between canine leishmaniosis and Ehrlichia canis co-infection: a prospective case-control study

Background

In the Mediterranean basin, Leishmania infantum is a major cause of disease in dogs, which are frequently co-infected with other vector-borne pathogens (VBP). However, the associations between dogs with clinical leishmaniosis (ClinL) and VBP co-infections have not been studied. We assessed the risk of VBP infections in dogs with ClinL and healthy controls.

Methods

We conducted a prospective case-control study of dogs with ClinL (positive qPCR and ELISA antibody for L. infantum on peripheral blood) and clinically healthy, ideally breed-, sex- and age-matched, control dogs (negative qPCR and ELISA antibody for L. infantum on peripheral blood) from Paphos, Cyprus. We obtained demographic data and all dogs underwent PCR on EDTA-blood extracted DNA for haemoplasma species, Ehrlichia/Anaplasma spp., Babesia spp., and Hepatozoon spp., with DNA sequencing to identify infecting species. We used logistic regression analysis and structural equation modelling (SEM) to evaluate the risk of VBP infections between ClinL cases and controls.

Results

From the 50 enrolled dogs with ClinL, DNA was detected in 24 (48%) for Hepatozoon spp., 14 (28%) for Mycoplasma haemocanis, 6 (12%) for Ehrlichia canis and 2 (4%) for Anaplasma platys. In the 92 enrolled control dogs, DNA was detected in 41 (45%) for Hepatozoon spp., 18 (20%) for M. haemocanis, 1 (1%) for E. canis and 3 (3%) for A. platys. No Babesia spp. or “Candidatus Mycoplasma haematoparvum” DNA was detected in any dog. No statistical differences were found between the ClinL and controls regarding age, sex, breed, lifestyle and use of ectoparasitic prevention. A significant association between ClinL and E. canis infection (OR = 12.4, 95% CI: 1.5–106.0, P = 0.022) was found compared to controls by multivariate logistic regression. This association was confirmed using SEM, which further identified that younger dogs were more likely to be infected with each of Hepatozoon spp. and M. haemocanis, and dogs with Hepatozoon spp. were more likely to be co-infected with M. haemocanis.

Conclusions

Dogs with ClinL are at a higher risk of co-infection with E. canis than clinically healthy dogs. We recommend that dogs diagnosed with ClinL should be tested for E. canis co-infection using PCR.

Does co-infection with vector-borne pathogens play a role in clinical canine leishmaniosis?

BACKGROUND

The severity of canine leishmaniosis (CanL) due to Leishmania infantum might be affected by other vector-borne organisms that mimic its clinical signs and clinicopathological abnormalities. The aim of this study was to determine co-infections with other vector-borne pathogens based on serological and molecular techniques in dogs with clinical leishmaniosis living in Spain and to associate them with clinical signs and clinicopathological abnormalities as well as disease severity.

METHODS

Sixty-one dogs with clinical leishmaniosis and 16 apparently healthy dogs were tested for Rickettsia conorii, Ehrlichia canis, Anaplasma phagocytophilum and Bartonella henselae antigens by the immunofluorescence antibody test (IFAT) and for E. canis, Anaplasma spp., Hepatozoon spp., Babesia spp. and filarioid DNA by polymerase chain reaction (PCR).

RESULTS

Among the dogs examined by IFAT, the seroprevalences were: 69% for R. conorii, 57% for E. canis, 44% for A. phagocytophilum and 37% for B. henselae; while the prevalences found by PCR were: 8% for Ehrlichia/Anaplasma, 3% for Anaplasma platys and 1% for H. canis. No other pathogen DNA was detected. Statistical association was found between dogs with clinical leishmaniosis and seroreactivity to R. conorii antigen (Fisher's exact test: P = 0.025, OR = 4.1, 95% CI = 1-17) and A. phagocytophilum antigen (Fisher's exact test: P = 0.002, OR = 14.3, 95% CI = 2-626) and being positive to more than one serological or molecular tests (co-infections) (Mann-Whitney test: U = 243, Z = -2.6, n ₁  = 14, n ₂  = 61, P = 0.01) when compared with healthy dogs. Interestingly, a statistical association was found between the presence of R. conorii, E. canis, A. phagocytophilum and B. henselae antibodies in sick dogs and some clinicopathological abnormalities such as albumin and albumin/globulin ratio decrease and increase in serum globulins. Furthermore, seroreactivity with A. phagocytophilum antigens was statistically associated with CanL clinical stages III and IV.

CONCLUSIONS

This study demonstrates that dogs with clinical leishmaniosis from Catalonia (Spain) have a higher rate of co-infections with other vector-borne pathogens when compared with healthy controls. Furthermore, positivity to some vector-borne pathogens was associated with more marked clinicopathological abnormalities as well as disease severity with CanL.

Histological and Immunological Description of the Leishmanin Skin Test in Ibizan Hounds

The leishmanin skin test (LST), a delayed-type hypersensitivity (DTH) reaction to Leishmania infantum, can specifically identify dogs that have made a cell-mediated immune response to L. infantum infection. The Ibizan hound appears to be more resistant to L. infantum infection than other breeds of dog. The aim of this study was to describe the histological and immunohistochemical changes induced by the LST in Ibizan hounds living in an area highly endemic for leishmaniosis. The majority of dogs were apparently healthy, lacked serum antibody to L. infantum and blood parasitaemia, but had marked specific interferon gamma production after in-vitro blood stimulation with L. infantum. Leishmanin (3 × 10⁸ killed promastigotes of L. infantum/ml) was injected intradermally and biopsy samples were obtained from a positive reaction at 72 h from nine Ibizan hounds. A moderate to intense, perivascular to interstitial dermatitis and panniculitis characterized the inflammatory response at the injection site. In addition, three samples had diffuse inflammation in the deep dermis and panniculus. Oedema and necrosis were present in the deep dermis and panniculus. Congestion and haemorrhage were observed in five biopsies. T lymphocytes (CD3⁺) and large mononuclear cells (lysozyme^-) were the most prevalent cells. CD3⁺ cells were significantly more numerous than CD20⁺ B cells and lysozyme⁺ cells. B cells were sparsely distributed, especially in the deep dermis and panniculus. Rare neutrophils and macrophages (lysozyme⁺) were observed with few eosinophils. Toll-like receptor (TLR)-2 protein was expressed in large mononuclear cells mainly located in the superficial dermis. Leishmania immunohistochemistry was negative and quantitative polymerase chain reaction was positive in all cases. The intradermal injection of killed L. infantum promastigotes in Ibizan hounds causes similar histological and immunohistochemical findings to those described for human subjects and are indicative of a DTH response. Moreover, TLR2 protein is expressed in inflammatory cells similar to findings in clinically affected skin biopsy samples.

Follow-up monitoring in a cat with leishmaniosis and coinfections with Hepatozoon felis and 'Candidatus Mycoplasma haemominutum'

Case summary

A 6-year-old female neutered domestic shorthair cat from Cyprus was presented with multiple ulcerated skin nodules. Cytology and histopathology of the lesions revealed granulomatous dermatitis with intracytoplasmic organisms, consistent with amastigotes of Leishmania species. Biochemistry identified a mild hyperproteinaemia. Blood extraction and PCR detected Leishmania species, Hepatozoon species and ‘Candidatus Mycoplasma haemominutum’ (CMhm) DNA. Subsequent sequencing identified Hepatozoon felis. Additionally, the rRNA internal transcribed spacer 1 locus of Leishmania infantum was partially sequenced and phylogeny showed it to cluster with species derived from dogs in Italy and Uzbekistan, and a human in France. Allopurinol treatment was administered for 6 months. Clinical signs resolved in the second month of treatment with no deterioration 8 months post-treatment cessation. Quantitative PCR and ELISA were used to monitor L infantum blood DNA and antibody levels. The cat had high L infantum DNA levels pretreatment that gradually declined during treatment but increased 8 months post-treatment cessation. Similarly, ELISA revealed high levels of antibodies pretreatment, which gradually declined during treatment and increased slightly 8 months post-treatment cessation. The cat remained PCR positive for CMhm and Hepatozoon species throughout the study. There was no clinical evidence of relapse 24 months post-treatment.

Relevance and novel information

To our knowledge, this is the first clinical report of a cat with leishmaniosis with H felis and CMhm coinfections. The high L infantum DNA levels post-treatment cessation might indicate that although the lesions had resolved, prolonged or an alternative treatment could have been considered.

Leishmania infantum-specific IFN-γ production in stimulated blood from dogs with clinical leishmaniosis at diagnosis and during treatment

There is limited data regarding Leishmania infantum specific T cell mediated immunity in naturally infected sick dogs at the time of diagnosis and during anti-Leishmania treatment. Our aim was to investigate the kinetics of L. infantum specific IFN-γ production in dogs with leishmaniosis at the time of diagnosis and during treatment and to correlate it with specific L. infantum antibodies, blood parasitemia and clinicopathological findings. Thirty-four dogs were diagnosed with leishmaniosis based on physical examination, routine laboratory tests and L. infantum-specific antibody levels by quantitative ELISA. Heparinized whole blood was stimulated with L. infantum soluble antigen (LSA) and concanavalin A (ConA) and incubated for 5days. IFN-γ concentration was evaluated in supernatants of stimulated blood using a commercial sandwich ELISA. Leishmania real-time PCR was also performed for assessing blood parasitemia. Dogs were treated with meglumine antimoniate and allopurinol. Sixteen dogs were classified as IFN-γ non-producers after LSA stimulation (mean±SD: 0±0pg/mL) and 18 dogs as IFN-γ producers (mean±SD: 2885.3±4436.1pg/mL) at the time of diagnosis (P<0.0001). IFN-γ non-producers were classified in a more severe clinical staging than IFN-γ producers that presented a mild to moderate clinical staging (P=0.03). In the IFN-γ non-producer group, production of IFN-γ after LSA stimulation was significantly increased during treatment especially at day 365 (P=0.018) together with clinical improvement when compared with day 0. In contrast, IFN-γ producers maintained their IFN-γ production after LSA stimulation and no statistically significant changes were found during treatment follow-up. At diagnosis, IFN-γ non-producers showed a significantly higher blood parasitemia versus IFN-γ -producers (P=0.005). IFN-γ non-producers drastically reduced blood parasitemia to minimum values at day 365 when compared with day 0 (P=0.017). No significant differences were found at day 365 in blood parasitemia of IFN-γ producers compared to pre-treatment. At diagnosis, L. infantum specific antibodies were higher in IFN-γ non-producers than IFN-γ producers (P=0.014). A marked reduction of antibody levels was found at day 365 when compared with day 0 in IFN-γ non-producers (P=0.005) and producers (P=0.001). These results demonstrate that IFN-γ concentration increases with long-term anti-Leishmania treatment together with clinical improvement in dogs that do not produce IFN-γ at diagnosis. Together with clinical recovery, reduction in blood parasitemia and L. infantum specific antibodies, tracking IFN-γ concentration could constitute an important prognostic tool for immune monitoring in CanL.

Diagnostic Challenges in the Era of Canine Leishmania infantum Vaccines

The diagnosis of canine leishmaniosis (CanL) is complex due to its variable clinical manifestations and laboratory findings. The availability of vaccines to prevent CanL has increased the complexity of diagnosis, as serological tests may not distinguish between naturally infected and vaccinated dogs. Current practices of prevaccination screening are not sufficiently sensitive to detect subclinically infected dogs, resulting in the vaccination of infected animals, which may lead to disease in vaccinated dogs that are also infectious to sand flies. This review evaluates the current techniques for diagnosing CanL, and focuses on new challenges raised by the increasing use of vaccines against this disease. Important gaps in knowledge regarding the diagnosis of CanL are underscored to highlight the need for novel diagnostic test development.

Novel Areas for Prevention and Control of Canine Leishmaniosis

There have been multiple recent advances regarding tools for the control and prevention of canine leishmaniosis (CanL), including new preventative vaccines. In this review, these advances are evaluated based on control targets, including vector and parasite. Leishvet recommendations are provided for control practices based on the dog's risk of infection. New topical insecticide formulations have proven to be effective in preventing sand fly bites, and subsequently infection. Parasite control occurs through chemotherapeutic or immunologic means, which decrease or prevent transmission to other animals, including humans. Leishmaniosis control programs that include a combination of coordinated measures, either in individuals or for prevention across reservoir populations, are required.

The inflammatory cytokine effect of Pam3CSK4 TLR2 agonist alone or in combination with Leishmania infantum antigen on ex-vivo whole blood from sick and resistant dogs

BACKGROUND

A wide spectrum of clinical manifestations and immune responses exist in canine L. infantum infection. Ibizan hounds are more "resistant" to disease than other dog breeds. Recognition of pathogen-associated molecule patterns by toll like receptors (TLRs) rapidly triggers a variety of anti-microbial immune responses through the induction of pro-inflammatory cytokines such as TNF-α and IL-6 which may play an important role in controlling Leishmania infection. The main objective of this study was to investigate and compare the effect of a TLR2 agonist (TLR2a) alone or in combination with L. infantum antigen (LSA) on ex vivo whole blood cytokine production from healthy seronegative IFN-γ non-producer dogs from an area of low in canine leishmaniosis endemicity (n = 11); sick seropositive dogs with low production of IFN-γ (n = 17) and healthy seronegative or low positive Ibizan hounds with a predominant IFN-γ production (n = 21) from a highly endemic area. Whole blood was stimulated with medium alone (Ø), LSA, concanavalin A, TLR2 (Pam3CSK4) receptor agonist (Ø + TLR2a) and TLR2a and LSA (LSA + TLR2a) for 48 h. Supernatants were harvested for measurement of canine TNF-α and IL-6 cytokines by ELISA.

RESULTS

A significant increase of TNF-α was found in the supernatants of stimulated blood from all groups (Ø + TLR2a and LSA + TLR2a) when compared with medium alone. A similar pattern was observed for IL-6. Interestingly, a significant increase of TNF-α production was only observed when stimulation with LSA + TLR2a was compared with TLR2a alone in Ibizan hounds. A significant increase of TNF-α production was observed with stimulation of LSA + TLR2a when compared with LSA in all groups. Significantly higher concentrations of TNF-α and IL-6 were detected in Ibizan hounds, especially for the Ø + TLR2a and LSA + TLR2a treatments compared with other groups.

CONCLUSIONS

This study demonstrated that TLR2a alone enhances the production of the inflammatory cytokines TNF-α and IL-6 in sick, "resistant" and healthy non-infected dogs. In addition, a combination of LSA+TLR2a promoted a synergistic pro-inflammatory effect with TNF-α in Ibizan hounds but not in seropositive sick dogs and seronegative healthy dogs. These findings might suggest the importance of Pam3CSK4 as a possible immunomodulator for CanL.

Histological and parasitological distinctive findings in clinically-lesioned and normal-looking skin of dogs with different clinical stages of leishmaniosis

Background

Normal-looking skin of dogs with leishmaniosis frequently shows microscopic lesions along with the presence of Leishmania amastigotes. However, histological lesions with or without detection of amastigotes might not occur in less severe clinical cases. In addition, comparative studies between paired clinically-lesioned and normal-looking skin samples from dogs with different disease severity are lacking. The objective of this study was to compare histological and parasitological findings by Leishmania immunohistochemistry (IHC) and quantitative PCR (qPCR) on paired clinically-lesioned and normal-looking skin biopsies from 25 dogs with different clinical stages of leishmaniosis, 11 with stage I-mild disease (papular dermatitis) and 14 with stage II-III (ulcerative or exfoliative dermatitis).

Results

The study demonstrated microscopic lesions in 14 out of 25 (56%) samples from normal-looking skin biopsies. In those samples, perivascular to interstitial dermatitis composed by macrophages with lymphocytes and plasma cells was observed mainly in the superficial and mid-dermis. The intensity of the dermatitis was mild to moderate and always less prominent than in the clinically-lesioned skin. In normal-looking skin samples, the presence of parasites was detected by histology, IHC and qPCR in 5/25 (20%), 8/25 (32%) and 18/25 (72%), respectively. Leishmania was encountered in 11/25 (44%), 23/25 (92%) and 25/25 (100%) of clinically-lesioned skin samples by histology, IHC and qPCR, respectively. Normal-looking skin from dogs with stage I-mild disease was less frequently inflamed (P = 0.0172). Furthermore, Leishmania was more easily demonstrated by histology (P = 0.0464), IHC (P = 0.0421) or qPCR (P = 0.0068) in normal-looking skin of dogs with stage II-III-moderate to severe disease. In addition, in the latter group, there was a significantly higher parasite load studied by means of qPCR than in dogs with less severe disease (P = 0.043). Clinically-lesioned skin from dogs with stage I disease was more frequently characterised by the nodular to diffuse pattern and granuloma formation (P = 0.0166) and by a lower parasite load studied by means of qPCR (P = 0.043) compared with more diseased dogs.

Conclusions

Normal-looking skin from dogs with stage I is less likely to present histological lesions as well as harbour the parasite when compared with dogs with moderate to severe leishmaniosis.

Diagnostic performance of ELISA, IFAT and Western blot for the detection of anti-Leishmania infantum antibodies in cats using a Bayesian analysis without a gold standard

Background

Anti-Leishmania antibodies are increasingly investigated in cats for epidemiological studies or for the diagnosis of clinical feline leishmaniosis. The immunofluorescent antibody test (IFAT), the enzyme-linked immunosorbent assay (ELISA) and western blot (WB) are the serological tests more frequently used. The aim of the present study was to assess diagnostic performance of IFAT, ELISA and WB to detect anti-L. infantum antibodies in feline serum samples obtained from endemic (n = 76) and non-endemic (n = 64) areas and from cats affected by feline leishmaniosis (n = 21) by a Bayesian approach without a gold standard.

Methods

Cut-offs were set at 80 titre for IFAT and 40 ELISA units for ELISA. WB was considered positive in presence of at least a 18 KDa band. Statistical analysis was performed through a written routine with MATLAB software in the Bayesian framework. The latent data and observations from the joint posterior were simulated in the Bayesian approach by an iterative Markov Chain Monte Carlo technique using the Gibbs sampler for estimating sensitivity and specificity of the three tests.

Results

The median seroprevalence in the sample used for evaluating the performance of tests was estimated at 0.27 [credible interval (CI) = 0.20–0.34]. The median sensitivity of the three different methods was 0.97 (CI: 0.86–1.00), 0.75 (CI: 0.61–0.87) and 0.70 (CI: 0.56–0.83) for WB, IFAT and ELISA, respectively. Median specificity reached 0.99 (CI: 0.96–1.00) with WB, 0.97 (CI: 0.93–0.99) with IFAT and 0.98 (CI: 0.94–1.00) with ELISA. IFAT was more sensitive than ELISA (75 vs 70%) for the detection of subclinical infection while ELISA was better for diagnosing clinical leishmaniosis when compared with IFAT (98 vs 97%).

Conclusions

The overall performance of all serological techniques was good and the most accurate test for anti-Leishmania antibody detection in feline serum samples was WB.