Search Results (32)

Compounds in sand fly saliva elicit specific immune responses that may play a role in the establishment of canine Leishmania infection. Although canine antibodies to anti-sand fly saliva antigens have been extensively studied, little is known about cellular immune responses against Phlebotomus perniciosus salivary proteins. This study aimed to explore humoral and T-cell-mediated immunity against P. perniciosus salivary proteins in dogs (n = 85) from Mallorca (Spain), a leishmaniosis-endemic area, and find correlations with demographic (age, sex, and breed) and parasite-specific immunological parameters. Anti-sand fly saliva IgG was examined using a P. perniciosus whole salivary gland homogenate (SGH) ELISA and recombinant salivary protein rSP03B ELISA. Interferon gamma (IFN-γ) release whole blood assays with L. infantum soluble antigen (LSA), SGH, and rSP03B were also performed. Positive correlations were found between IgG levels in the SGH and rSP03B tests and between concentrations of SGH IFN-γ and rSP03B IFN-γ. While concentrations of SGH IFN-γ and rSP03B IFN-γ were low and produced only by a minority of dogs (less than 20%), high levels and frequencies of LSA IFN-γ as well as anti-saliva IgG for SGH and rSP03B were detected in a majority of dogs (61% and 75%, respectively). LSA IFN-γ levels were positively correlated with age and Leishmania-specific antibodies. In conclusion, dogs from a leishmaniosis-endemic area presented high humoral immunity against P. perniciosus salivary proteins, but their cellular immunity to these proteins was low and less frequent. Full article

Cutaneous lesions suggestive of vasculitis and/or ischemic dermatopathy (ID) are anecdotally reported in canine leishmaniosis, and the clinicopathological features of these conditions have not been fully characterized. The objective of this case series was to describe six dogs with leishmaniosis and ID. In 5/6 dogs, leishmaniosis was diagnosed at the time of ID diagnosis, whereas in 1/6 dogs, ID developed during the first month of anti-Leishmania conventional treatment. One each of greyhound, Chihuahua, whippet, American bully, hound and mixed breeds were represented, and the median age at presentation was 6 years [2–8]. All patients presented high or very high levels of circulating anti-Leishmania infantum antibodies. The cutaneous lesions were multifocal alopecia with atrophic skin with hyper- or hypopigmentation (6/6), ulcers located on the extremities and trunk (3/6) and onychodystrophy (2/6). Histologically, ID was confirmed by the presence of follicular atrophy (faded follicles) (6/6), perivascular or interstitial lymphoplasmacytic dermatitis or panniculitis (6/6), collagen smudging (3/6), dermal fibrosis (3/6), lymphocytic interface dermatitis (3/6) and ulceration (3/6). Vasculopathy was observed in the superficial and mid-vascular plexuses in 4/6 dogs and characterized by the combination of some of the following lesions: vasocongestion, hemorrhagic foci, mild hyaline mural degeneration, thrombi and fragmented degenerating nuclear debris of neutrophils in the vascular wall. Moreover, myositis was observed in 1/6 cases. Leishmania-specific immunohistochemistry was positive in the skin of 4/6 cases. Leishmaniosis might be considered an underlying cause of ID in dogs. However, the immune mechanisms and pathogenesis need to be elucidated. Full article

The course and outcome of infection with the parasitic protozoa Leishmania major depends on the host immune response which, itself, depends mainly on the cytokine milieu, especially early in the infection. It is widely accepted that INF-γ, TNF-α, and IL-12 usually favor a protective response, while IL-4, IL-5, IL-10, and IL-13 favor a pathogenic one. These and other cytokines also play a major role in Leishmania-induced hyperalgesia via two possible pathways, one involving prostaglandins and the other sympathetic amines as final mediators, preceded by a cascade of cytokines, among which TNF-α seems to play a pivotal role via a still unclear mechanism of action. This study investigates the effects of anti-TNF-α antibody (Infliximab) on L. major-induced hyperalgesia in susceptible BALB/c mice using the hot plate and tail flicks tests, as well as the levels of many cytokines in the infected paws of mice using the ELISA technique. In addition, the parasite burden was assessed using the serial dilution method. Our results show that Infliximab can reduce the induced hyperalgesia, up-regulate TNF-α, IL-1β, and keratinocyte-derived chemokine (KC), and down-regulate IL-10 and IL-17 in the paws of infected mice. Infliximab may also have beneficial effects on the prognosis of cutaneous leishmaniasis by reducing the parasite burden. Full article

Background: Toxoplasmosis has been of public health concern due to direct associations with socioeconomic vulnerability and inadequate living conditions. Methods: Accordingly, the present study aimed to assess antibodies against T. gondii, historical reported toxoplasmosis cases and associated socio-environmental risk factors in Pinhais, a full urban area of Curitiba, currently the eighth biggest metropolitan area of Brazil. Anti-Toxoplasma gondii antibodies were assessed by an indirect immunofluorescence reaction (RIFI). Owner and dog samples were also tested by IFAT to anti-Leishmania spp. and anti-Trypanosoma cruzi antibodies. Results: Overall, 20/135 (14.8%) persons and 13/133 (9.8%) dogs from 25 different households were considered seropositive to T. gondii. All samples were seronegative to Leishmania spp. and Trypanosoma cruzi. Conclusions: Although no significant covariates were found in the regression model, statistically associated risk factors in the bivariate analysis included no public water use (p = 0.016) and drinking raw milk (p = 0.041) for owners, and obesity (p = 0.028) and tick infestation (p = 0.03) for dogs. In addition, a spatial cluster of T. gondii seropositivity for both owners and their dogs overlapped the location of historic reported cases of human acquired, gestational and congenital toxoplasmosis. Finally, the results herein showed tick infestation as an indicator of socio-environmental risk for T. gondii exposure in the household environment, and dogs may be used as sentinels for human toxoplasmosis cases. Full article

Leishmaniasis in wild canids is a vector-borne disease caused in Europe by the protozoan parasite Leishmania infantum. To date, there is limited information on clinical signs and laboratory abnormalities in wolves due to leishmaniasis. The current clinical case report described a female Iberian wolf (Canis lupus signatus) housed in semi-captivity conditions at the Centro del Lobo Ibérico “Félix Rodríguez de la Fuente”, in Robledo de Sanabria, Zamora (Spain), with an interdigital ulcerous wound at the right forepaw, hyper-gammaglobulinemia, and abnormal liver blood parameters. Definitive serodiagnosis of leishmaniasis was established using antileishmanial serum antibodies and PCR analysis of different biological samples. A gold-standard anti-L. infantum treatment protocol consisting in subcutaneous meglumine antimoniate and oral allopurinol combination was installed. However, the presence of pain at the site of injection due to meglumine antimoniate administration forced its substitution by oral miltefosine. A progressive reduction of the levels of anti-L. infantum serum antibodies and the concentrations of gamma-globulin fraction was detected after antileishmanial treatment as well as a decline of liver GPT. To our knowledge, this is the first case of leishmaniasis diagnosed in a wolf housed in semi-captivity conditions, with the condition subsequently treated and successfully cured. Full article

The diagnosis of canine leishmaniasis (CanL) still represents a challenge due to the variable clinical manifestations and the large number of asymptomatic dogs. Serological tests are most commonly used to detect infected animals, revealing anti-Leishmania antibodies, mainly of the IgG isotype. Recently, a new diagnostic antigen, rKLi8.3, containing 8.3 kinesin tandem repeats (TR) from a Leishmania infantum strain from Sudan, has been shown to provide excellent specificity and sensitivity for the detection of Leishmania-infected humans and dogs. However, asymptomatic animals with very low antibody titers are often difficult to detect by serodiagnosis. Thus, we wondered whether the addition of an anti-IgG-enhancing step in the protein A/G-based rKLi8.3-ELISA will improve the diagnostic performance without decreasing the specificity. For this, parasitologically confirmed CanL cases with low or high clinical scores, uninfected healthy controls and dogs with other infections were tested by rKLi8.3-ELISA as well as two different immunochromatographic rapid tests, rKLi8.3-lateral flow test (LFT) and Dual Path Platform (DPP^®) based on the rK28 antigen. Our results show that the diagnostic accuracies of the rKLi8.3-ELISA and LFT were similar to that of DPP, missing several asymptomatic animals. However, the addition of a secondary, amplifying anti-dog IgG antibody in the protein A/G-based rKLi8.3-ELISA enabled the detection of nearly all asymptomatic dogs without compromising its specificity. Full article

The mucosal immune system plays a pivotal role in the control of infections, as it represents the first line of defense against most pathogens, from respiratory viruses to intestinal parasites. Mucosal vaccination is thus regarded as a promising strategy to protect animals, including humans, from infections that are acquired by ingestion, inhalation or through the urogenital system. In addition, antigens delivered at the mucosal level can also elicit systemic immune responses. Therefore, mucosal vaccination is potentially effective also against systemic infections acquired through non-mucosal routes, for example, through the bite of hematophagous insects, as in the case of leishmaniasis, a widespread disease that affects humans and dogs. Here, we explored the potential of antigen rectal administration for the generation of anti-Leishmania immunity. Mice were immunized through rectal administration of whole cells of the model parasite Leishmania tarentolae (using a clone engineered to express the spike protein of the SARS-CoV-2 virus generated in a previous study). A specific anti-Leishmania IgG antibody response was detected. In addition, the recorded IgG2a/IgG1 ratio was higher than that of animals injected subcutaneously; therefore, suggesting a shift to a Th1-biased immune response. Considering the importance of a Th1 polarization as a protective response against Leishmania infections, we suggest that further investigation should be focused on the development of novel types of vaccines against these parasites based on rectal immunization. Full article

Background and objectives: Feline leishmaniasis (FeL) is caused by several species of parasites of the genus Leishmania. The disease can occur with the presence or absence of clinical signs, similar to those observed in other common infectious diseases. In endemic regions for FeL, the infection has been associated with dermatological lesions. Therefore, considering the search for less invasive and more effective diagnostic techniques, we aimed to investigate the presence of Leishmania spp. in domestic cats through Polymerase Chain Reaction (PCR) and high-resolution melting (HRM) analyses of conjunctival, oral, and nasal epithelial cells, and we detected the presence of anti-Leishmania IgG antibodies from serological techniques of the Immunofluorescent Antibody Test (IFAT) and ELISA. Methods: The PCR and HRM for detection of Leishmania spp. were performed on 36 samples of epithelial cells from the conjunctiva of male and female cats, collected using sterile swabs. The serological tests IFAT and ELISA were also performed. Results: The prevalence of Leishmania donovani infection was 11.1% (4/36) by PCR assay, and those results were confirmed for Leishmania species using the HRM technique. Twenty-four cats (24/36 = 66.7%) were reactive to the IFAT and twenty-two cats were reactive by the ELISA technique (22/36 = 61.1%). Interpretation and Conclusions: The use of conjunctival swabs was shown to be a non-invasive, practical, and easy-to-perform technique, and in addition to the genetic sequencing and HRM, it was able to identify the parasitic DNA of L. donovani in cats. This technique can be used for screening diagnosis in future epidemiological surveys of FeL and can be used as a complement to clinical and/or serological tests, as well as associating the clinical history of the animal, for the diagnostic conclusion. Full article

Visceral canine leishmaniasis (CanL) can cause several clinical manifestations, including neurological lesions. Few reports have characterized the lesions observed in the central nervous system (CNS) during CanL; however, its pathogenesis remains unclear. The choroid plexus (CP) is a specialized structure responsible for the production and secretion of cerebrospinal fluid (CSF) and considered an interface between the peripheral immune system and CNS. It can allow the passage of inflammatory cells or pathogens and has the potential to act as a source of inflammatory mediators in several diseases. Thus, this study aimed to evaluate the role of CP as a possible route of inflammatory cells in the development of brain lesions in dogs with CanL, as well as its association with blood–CSF barrier (BCSFB) dysfunction. Samples were collected from 19 dogs that were naturally infected with CanL. We evaluated the histopathological lesions in the brain and investigated the gene expression of the cytokines. Capture enzyme-linked immunosorbent assay (ELISA) was used to evaluate the presence of the same cytokines in the CSF. Biochemical analysis was performed to compare the presence of albumin in the serum and CSF. Indirect ELISA was performed to measure the presence of anti-Leishmania antibodies in the CSF, which would suggest the disruption of the BCSFB. Histopathological evaluation of the dogs’ brains revealed mild-to-severe inflammatory infiltrates, mainly in the CP and meninges. We also detected the presence of anti-Leishmania antibodies and albumin in the CSF, as well as Leishmania DNA in the CP. The gene expression of CCL-5 was increased in the CP of infected dogs compared with that of controls, and there was a tendency for the increase in the gene expression of CXCL-10. Thus, our findings confirm the disfunction of the BCSFB during CanL and suggest that the chemokines CCL-5 and CXCL-10 can be responsible for the recruitment of inflammatory cells found in CP. Full article

Visceral leishmaniasis (VL) in the Americas is a chronic systemic disease caused by infection with Leishmania infantum parasites. The toxicity of antileishmanial drugs, long treatment course and limited efficacy are significant concerns that hamper adequate treatment against the disease. Studies have shown the promise of an immunotherapeutics approach, combining antileishmanial drugs to reduce the parasitism and vaccine immunogens to activate the host immune system. In the current study, we developed an immunotherapy using a recombinant T cell epitope-based chimeric protein, ChimT, previously shown to be protective against Leishmania infantum, with the adjuvant monophosphoryl lipid A (MPLA) and amphotericin B (AmpB) as the antileishmanial drug. BALB/c mice were infected with L. infantum stationary promastigotes and later they received saline or were treated with AmpB, MPLA, ChimT/Amp, ChimT/MPLA or ChimT/MPLA/AmpB. The combination of ChimT/MPLA/AmpB significantly reduced the parasite load in mouse organs (p < 0.05) and induced a Th1-type immune response, which was characterized by higher ratios of anti-ChimT and anti-parasite IgG2a:IgG1 antibodies, increased IFN-γ mRNA and IFN-γ and IL-12 cytokines and accompanied by lower levels of IL-4 and IL-10 cytokines, when compared to other treatments and controls (all p < 0.05). Organ toxicity was also lower with the ChimT/MPLA/AmpB immunotherapy, suggesting that the inclusion of the vaccine and adjuvant ameliorated the toxicity of AmpB to some degree. In addition, the ChimT vaccine alone stimulated in vitro murine macrophages to significantly kill three different internalized species of Leishmania parasites and to produce Th1-type cytokines into the culture supernatants. To conclude, our data suggest that the combination of ChimT/MPLA/AmpB could be considered for further studies as an immunotherapy for L. infantum infection. Full article

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. Full article

Ruxolitinib is a JAK1/2 inhibitor that has revolutionized the approach to myelofibrosis. On the one side, this drug can rapidly improve the symptoms related to the hematological disease; on the other side, the inhibition of JAK1/2 can lead to immunosuppression which may increase the risk of infections, due to a change in the cytokine balance in favor of anti-inflammatory cytokines, to direct inhibition of immune cells, and to the suppression in the production of specific antibodies. In this patient setting, much is known about possible viral and bacterial infections, while little is reported in the literature concerning parasitic infections, specifically leishmaniasis. Leishmania is a parasitic infection that can cause serious problems in immunosuppressed patients. The parasite can invade the bloodstream and cause a wide range of symptoms, including fever, weight loss, and anemia. In severe cases, it can lead to multi-organ failure and, rapidly, death. Early diagnosis and prompt treatment are essential especially for these patients, unable to respond adequately. In this case and the following review of the existing literature, the cytokine kinetics and the production of specific anti-Leishmania antibodies represent characteristic aspects capable of providing a more in-depth understanding of the mechanisms underlying these complex clinical cases in an immunocompromised patient. Full article

Leishmania donovani causes both cutaneous and visceral leishmaniasis (CL and VL) in Sri Lanka, where chronic kidney disease (CKD) and kidney transplant recipients’ (KTR) geographical areas overlap. This study aimed to determine the risk of exposure to Leishmania infection among renal patients. This cross-sectional study in a renal unit assessed clinical symptoms and signs of CL and VL in recipients of blood/kidney or immunosuppressives. Sera were tested with Leishmania-specific DAT and rK-39 ELISA. There were 170 participants. A total of 84.1% (n = 143) were males (CKD: 101, KTR; 42, mean age 45) and 27 were females (females: CKD: 23, KTR: 4, mean age 39 years). Recipients of blood transfusion/s within last 2 years: 75.9% (CKD: 115, KTR: 14), on immunosuppressive therapy: 34.1% (CKD: 13, KTR: 45). Two CKD patients repeatedly showed clear positive titres (1: 12,800 and 1: 3200) with Leishmania-DAT and another two (CKD) became marginally positive with rK39-ELISA. Prevalence of anti-Leishmania antibodies: 2.4% (4/170). All four patients were clinically asymptomatic and were recipients of recent blood transfusions. Attributable risk of exposure to Leishmania infection through blood transfusions was 0.032, OR 2.99 (95% CI = 0.16 to 56.45, p = 0.47). Therefore, routine screening of kidney/blood donors and CKD and KTR patients in Sri Lanka may not be necessary. Full article

Canine leishmaniosis (CanL) caused by Leishmania infantum is an important zoonosis in southwestern European countries where this disease is endemic, and dogs, as domestic animals in close contact with humans, are the reservoir hosts for the parasite. In Portugal, CanL is of relevant veterinary concern. The previous national study revealed an overall seroprevalence of 6.3%. Since then, new prophylactic measures, such as vaccines, have been introduced in Europe. The aim of this study was to update seroprevalence for Leishmania infection and reassess risk factors in Portugal. A cross-sectional study was conducted from January–March 2021 with 1860 client-owned dogs from continental Portugal. A questionnaire and whole blood samples on filter paper were collected and a direct agglutination test was used to calculate anti-Leishmania antibody titres. True seroprevalence was 12.5% (95% CI 10.3–13.2%). Potential risk factors associated with L. infantum infection in dogs were age ≥ 2 years (aOR = 1.68, 95% CI 1.1–2.6) and residing in the interior regions of the country (aOR = 1.92, 95% CI 1.3–2.9) and non-use of repellents (aOR = 1.75, 95% CI 1.2–2.5). The key to controlling CanL and its impact on Public Health in endemic areas lies in continuous implementation of prophylactic measures, through the correct use of repellents/insecticides and vaccines and early detection and monitoring of infected dogs. Full article

Leishmaniasis is a widespread vector-borne disease in Brazil, with Leishmania (Leishmania) infantum as the primary etiological agent of visceral leishmaniasis (VL). Dogs are considered the main reservoir of this parasite, whose treatment in Brazil is restricted to the use of veterinary medicines, which do not promote a parasitological cure. Therefore, efficient vaccine development is the best approach to Canine Visceral Leishmaniasis (CVL) control. With this in mind, this study used hamsters (Mesocricetus auratus) as an experimental model in an anti-Leishmania preclinical vaccine trial to evaluate the safety, antigenicity, humoral response, and effects on tissue parasite load. Two novel formulations of nanoparticles made from poly(D, L-lactic) acid (PLA) polymer loading Leishmania braziliensis crude antigen (LB) exhibiting two different particle sizes were utilized: LBPSmG (570 nm) and LBPSmP (388 nm). The results showed that the nanoparticles were safe and harmless to hamsters and were antigenic with the induction in LBSap, LBPSmG, and LBPSmG groups of total anti-Leishmania IgG antibodies 30 days after challenge, which persists 200 days in LBSap and LBPSmP. At the same time, a less pronounced hepatosplenomegaly in LBSap, LBPSmG, and LBPSmP was found when compared to control groups, as well as a less pronounced inflammatory infiltrate and granuloma formation in the spleen. Furthermore, significant reductions of 84%, 81%, and 90% were observed in spleen parasite burden accessed by qPCR in the LBSap, LBPSmG, and LBPSmP groups, respectively. In this way, LBSap, LBPSmG, and LBPSmP formulations showed better results in vaccinated and L. infantum-challenged animals in further reducing parasitic load in the spleen and attenuating lesions in liver and splenic tissues. This results in safe, harmless nanoformulation vaccines with significant immunogenic and infection control potential. In addition, animals vaccinated with LBPSmP had an overall reduction in parasite burden in the spleen, indicating that a smaller nanoparticle could be more efficient in targeting antigen-presenting cells. Full article