The effect of intravenous or subcutaneous administration of meglumine antimonate (Glucantime) in dogs with leishmaniasis. A randomized clinical trial

Survival time and prognostic factors in canine leishmaniosis in a non-endemic country treated with a two-phase protocol including initial allopurinol monotherapy

BACKGROUND

Leishmania infantum is an intracellular protozoan parasite which is endemic in countries of the Mediterranean Basin. Leishmaniosis is increasingly diagnosed in non-endemic areas due to the relocation of dogs from endemic areas and the travel of dogs to and from these areas. The prognosis of leishmaniosis in these dogs may differ from that of those in endemic areas. The aims of this study were (1) to determine the Kaplan-Meier estimated survival time for dogs with leishmaniosis in the Netherlands (a non-endemic country), (2) to determine if clinicopathological variables at the time of diagnosis predicted the survival of these dogs, and (3) to evaluate the effect of a two-phase therapy protocol of allopurinol monotherapy followed by meglumine antimoniate and/or miltefosine in the case of incomplete remission or relapse.

METHODS

The database of the Department of Clinical Sciences of Companion Animals of the Faculty of Veterinary Medicine, Utrecht University was investigated for leishmaniosis patients. Patient records were reviewed for signalment and clinicopathological data at the time of diagnosis. Only treatment-naive patients were included. Follow-up was performed during the study by phone contact and included treatment received and date and cause of death. Univariate analysis was performed using the Cox proportional hazards regression model.

RESULTS

The estimated median Kaplan-Meier survival time was 6.4 years. In the univariate analysis, increases in monocyte, plasma urea and creatinine concentrations, and urine protein to creatinine ratio were all significantly associated with decreased survival time. The majority of patients only received allopurinol monotherapy.

CONCLUSIONS

Canine leishmaniosis patients in our study population in the Netherlands, which is non-endemic for the disease, had an estimated Kaplan-Meier median survival time of 6.4 years, which is comparable to the outcome of other reported therapy protocols. Increased plasma urea and creatinine concentrations and monocyte concentration were statistically associated with an increased risk of death. We conclude that initial allopurinol monotherapy for 3 months should be effective in more than half of canine leishmaniosis cases, provided there is adequate follow-up, and that meglumine antimoniate or miltefosine therapy should be started as the second phase of the protocol in cases where remission is incomplete or there is a relapse.

Scientometric analysis of chemotherapy of canine leishmaniasis (2000-2020)

Background

Zoonotic visceral leishmaniasis by Leishmania infantum is a first-order pathology in canine veterinary clinics in endemic areas. Moreover, canine infections are considered the main reservoir for human disease; despite their importance in the control of the disease within a One Health approach, no scientometric study has been published. Aims of the study included analyzing the impact of canine leishmaniasis (CanL) on the scientific literature, drugs or combinations used, trends in the period from 2000 to 2020 and efficacy criteria employed.

Methods

A Web of Science (WOS)-based analysis of publications on CanL and chemotherapy of the disease in the period 2000–2020 was carried out using a stepwise methodology. Data were analyzed by year, geographical origin, chemical groups, drugs and combinations, and efficacy criteria.

Results

Reports on CanL (n = 3324) represented < 16% of all publications on leishmaniasis (n = 20,968), and of these around 18% (n = 596) were related to chemotherapy. Publication records on CanL followed the distribution of the infection by L. infantum in endemic areas although Mediterranean countries were overrepresented in the reports on chemotherapy of CanL. Publications on the main antileishmanial drugs used in clinical practice showed a sustained tendency in the period analyzed. Pentavalent antimonials (Sb^V), alone or in combination with allopurinol, represented > 50% of all publications on chemotherapy of CanL despite the availability of more recently marketed drugs.

Conclusions

Chemotherapy of CanL still relies on Sb^V and combinations and to a lesser extent on miltefosine (MIL). Reports on chemotherapy are scarce and mostly publicly funded, and the variability of experimental conditions hampers the direct comparison of the efficacy of drugs, combinations and schedules. The vast majority of reports on efficacy do not include any information on supportive therapy; this reduces the actual value of the studies if intended for the practical management of the disease. Complete reports on the chemotherapy (etiological + symptomatic) would add value to the trials performed.

Parasitic load and histological aspects in different regions of the spleen of dogs with visceral leishmaniasis

Leishmania infantum causes from subclinical infection to severe disease in humans and dogs. The spleen is one of the organs most affected by the infection. Although evidence exists that the parasitic load distribution and histological alterations may not be homogeneous in the affected organs of naturally infected individuals, it has not been formally demonstrated using the current techniques used for studying the disease. In six dogs naturally infected with Leishmania, parasitic load and histological changes were compared in samples collected from the lower, middle and upper third of the spleen. Parasitic load in the spleen of the group of dogs was variable, revealing a difference of 61 times between animals with the lowest and the highest parasitism. The set of parasitic load values of each dog showed a cluster trend, when compared to the other animals. Nevertheless, the parasitic load values of each dog showed a variation ranging from 3.2 to 34.7 times between lowest and highest value. Histological changes showed recognizable variation in frequency (granulomas) or intensity (perisplenitis) in the spleen of 2 out of the 6 dogs. The agreement of histological findings between samples collected from the different thirds of the spleen was good (kappa coeficient, 0.61-0.80) very good (0.81-0.99) or perfect (1.00), for most of the parameters analyzed. Variability of parasitic load and, to a lesser extent, histological changes in spleen of dogs with visceral leishmaniasis is observed. Such variability may be taken in account in the design of studies on pathogenesis, vaccine and therapeutic drug development.

Current status on prevention and treatment of canine leishmaniasis

Canine leishmaniasis (CanL) is a parasite-borne disease mainly induced by Leishmania infantum in the Old World and Leishmania chagasi (infantum) in the New World. CanL is a zoonosis transmitted by the bite of infected Phlebotominae flies that act as vectors. CanL is a very serious disease that usually produces death when remains untreated and can be a focus of transmission to other dogs or humans. Infected dogs and other domestic and wild animals act as reservoirs and are a real threat to uninfected/healthy dogs and humans in endemic areas where the sand flies are present. Prevention of new infections in dogs can help to stop the current increase of the disease in humans, reinforcing the concept of "One Health" approach. The management of CanL is being performed using prophylactic measures in healthy dogs - insecticides impregnated in collars or immunostimulants applied by spot-on devices - and chemotherapy in animals that suffer from the disease. Antimonials as first-line monotherapy have proven efficacy in reducing most of the clinical signs of CanL, but they need to be administered during several days, and no complete parasite clearance is achieved, favouring the presence of relapses among treated dogs. Therefore, new drugs, such as miltefosine, or combinations of this drug or antimonials with allopurinol are in the pipeline of clinical treatment of CanL. Recently, there has been an emergence of protective - prophylactic - and curative - autogenous vaccines - immunotherapy tools to face CanL, whose results are still under study. This review highlights the current use of preventive and eradicative weapons to fight against this disease, which is a scourge for dogs and a continuous threat to human beings.

Allopurinol Resistance in Leishmania infantum from Dogs with Disease Relapse

BACKGROUND

Visceral leishmaniasis caused by the protozoan Leishmania infantum is a zoonotic, life threatening parasitic disease. Domestic dogs are the main peridomestic reservoir, and allopurinol is the most frequently used drug for the control of infection, alone or in combination with other drugs. Resistance of Leishmania strains from dogs to allopurinol has not been described before in clinical studies.

METHODOLOGY/PRINCIPAL FINDINGS

Following our observation of clinical disease relapse in dogs under allopurinol treatment, we tested susceptibility to allopurinol of L. infantum isolated from groups of dogs pre-treatment, treated in remission, and with disease relapse during treatment. Promastigote isolates obtained from four treated relapsed dogs (TR group) showed an average half maximal inhibitory concentration (IC50) of 996 μg/mL. A significantly lower IC50 (P = 0.01) was found for isolates from ten dogs before treatment (NT group, 200 μg/mL), as well as for five isolates obtained from treated dogs in remission (TA group, 268 μg/mL). Axenic amastigotes produced from isolates of the TR group also showed significantly higher (P = 0.002) IC50 compared to the NT group (1678 and 671 μg/mL, respectively). The lower sensitivity of intracellular amastigotes from the TR group relative to those from the NT group (P = 0.002) was confirmed using an infected macrophage model (6.3% and 20% growth inhibition, respectively at 300 μg/mL allopurinol).

CONCLUSIONS

This is the first study to demonstrate allopurinol resistance in L. infantum and to associate it with disease relapse in the canine host. These findings are of concern as allopurinol is the main drug used for long term control of the disease in dogs, and resistant L. infantum strains may enhance uncontrolled transmission to humans and to other dogs.

Modelling canine leishmaniasis spread to non-endemic areas of Europe

Expansion of sandflies and increasing pet travel have raised concerns about canine leishmaniasis (CanL) spread to new areas of Europe. This study aimed to estimate the probability of CanL introduction and persistence following movements of infected dogs. Stochastic modelling was used to estimate the probabilities of (1) CanL infection during travels or imports of infected dogs (P inf and P infCA, respectively), (2) CanL persistence in a dog network with sandflies after introduction of an infected dog (P per), and (3) persistence in a CanL-free region (P per region) for N dogs moving between endemic and free regions. Different mitigation measures (MMs) were assessed. P inf [7.8%, 95% predictive interval (PI) 2.6-16.4] and P per (72.0%, 95% PI 67.8-76.0) were reduced by use of repellent, vaccine, prophylactic medication, and insecticide, in decreasing order of effectiveness. Testing and exclusion of positive dogs was most effective in reducing P per region for a small N. The spread of CanL to CanL-free areas with sandflies is thus likely, but can be reduced by MMs.

Immunotherapy and Immunochemotherapy in Visceral Leishmaniasis: Promising Treatments for this Neglected Disease

Leishmaniasis has several clinical forms: self-healing or chronic cutaneous leishmaniasis or post-kala-azar dermal leishmaniasis; mucosal leishmaniasis; visceral leishmaniasis (VL), which is fatal if left untreated. The epidemiology and clinical features of VL vary greatly due to the interaction of multiple factors including parasite strains, vectors, host genetics, and the environment. Human immunodeficiency virus infection augments the severity of VL increasing the risk of developing active disease by 100–2320 times. An effective vaccine for humans is not yet available. Resistance to chemotherapy is a growing problem in many regions, and the costs associated with drug identification and development, make commercial production for leishmaniasis, unattractive. The toxicity of currently drugs, their long treatment course, and limited efficacy are significant concerns. For cutaneous disease, many studies have shown promising results with immunotherapy/immunochemotherapy, aimed to modulate and activate the immune response to obtain a therapeutic cure. Nowadays, the focus of many groups centers on treating canine VL by using vaccines and immunomodulators with or without chemotherapy. In human disease, the use of cytokines like interferon-γ associated with pentavalent antimonials demonstrated promising results in patients that did not respond to conventional treatment. In mice, immunomodulation based on monoclonal antibodies to remove endogenous immunosuppressive cytokines (interleukin-10) or block their receptors, antigen-pulsed syngeneic dendritic cells, or biological products like Pam3Cys (TLR ligand) has already been shown as a prospective treatment of the disease. This review addresses VL treatment, particularly immunotherapy and/or immunochemotherapy as an alternative to conventional drug treatment in experimental models, canine VL, and human disease.

Methods of Control of the Leishmania infantum Dog Reservoir: State of the Art

Leishmania infantum is a protozoan parasite causing severe vector-borne visceral diseases both in humans and dogs. The latter are the most important natural reservoir and therefore should be the main target of control measures. The real efficacy of seropositive dogs culling as a direct control method is still debated, and the new sensitivity of large part of population considers ethically unacceptable this kind of approach. Treatment of infectious dogs with one of the available therapeutic protocols is recommendable as it allows to reduce parasite burdens and therefore the possibility of transmission of Leishmania infantum to vectors. Vaccination has been proven to be a very effective control tool, but the absence of a commonly recognized diagnostic method able to distinguish vaccinate from seropositive individuals is still an important limit. Concerning indirect control methods, a number of studies have demonstrated the efficacy of topical insecticides treatment (collars, spot-on, and sprays) in reducing incidence and prevalence of L. infantum. Also, the reduction of the odds of seroconversion in humans in endemic areas has been reported after the application of indirect control measures on dogs. The contemporary use of direct and indirect methods is even more effective in reducing seroprevalence in dogs.

Microscopic evaluation of renal changes in experimental canine visceral leishmaniosis after chemo- and immunotherapy

Visceral Leishmania (VL) with diverse clinical manifestation is prevalent and remains a major public health problem in Iran. This study was performed in Ahwaz, Khozestan province southwest to increase immune system and to reduce of the renal lesions. Treatment of dogs with visceral leishmaniosis is basically the same as the treatment of human. However, cure is not usually achieved, leaving the sacrifice of animal as the only feasible choice. The goal of this work was to test the therapeutic efficacy of N-methyl glutamic antimoate (glucnime), Mycobacterium vaccae adjuvant (SRL 172), alone and in association with L. major promastigote and the latter compound in association to glucantime, in dog with visceral leishmaniasis. In this trial 18, mixed bred dogs with different ages, receiving amastigte promastigote of L. infantum intravenously were used. They were monitored for 6 months. Serologic assays (Elisa, Dot and IFAT) were performed on blood samples of each animal. The animals were divided into six groups, each having 3 dogs: Group 1: receiving 100 mg kg(-1) day(-1) Glucantime for 30 days, IM. Group 2: Receiving 3 mg dog(-1) (0.1 mL) of Mycobacterium vaccae adjuvant suspension intradermaly. Group 3: receiving L. major promastigote plus M. vaccae adjuvant each of them 0.1 mL intradermaly by one month intervals for 3 months. Group 4: receiving Glucantime in association L. major promastigote plus M. vaccae adjuvant with previous doses. Group 5: Receiving no treatment. Group 6: was control group with no infection and treatment. In microscopic evaluation following lesions have been shown in kidney: Chronic, interstitial nephritis, sever glomerulosclerosis, membranoproliferative glomerulonephritis and also non suppurative nephritis were the lesions in 5 groups. The prescription of Mycobacterium vaccae adjurant was able to reduce the number of parasites in the macrophages of liver and spleen in this round of treatment.

Treatment of canine Old World visceral leishmaniasis: a systematic review

Canine visceral leishmaniasis is a systemic disease caused by Leishmania infantum. The aim of this systematic review was to identify and evaluate the evidence of efficacy of interventions for treatment or prevention of canine visceral leishmaniasis, and to propose recommendations for or against their use. Forty-seven articles describing clinical trials published between 1980 and 2004 fulfilled selection criteria. The evaluation of clinical trials provided good evidence for recommending the use of meglumine antimoniate at a minimum dosage of 100 mg kg(-1) daily for at least 3-4 weeks, combined with allopurinol in order to obtain a good clinical efficacy and a reduced relapse rate. The evaluation of the articles also provided fair evidence for recommending the use of pentamidine (4 mg kg(-1) twice weekly) and aminosidine (5 mg kg(-1) twice daily) for 3-4 weeks. There was insufficient evidence for recommending the use of allopurinol alone, amphotericin B, buparvaquone, ketoconazole, enrofloxacin, and the combinations of metronidazole with spiramicyn or metronidazole with enrofloxacin. Fair evidence against the use of aminosidine at high dosages (20-80 mg kg(-1) per day) was proposed due to its side effects. Evaluation of articles on repellent measures against sand fly vectors of leishmaniasis provided good evidence for recommending deltamethrin collars and fair evidence for recommending spot-on permethrin.

Canine Leishmaniasis

Canine leishmaniasis is caused by Leishmania infantum (syn. L. chagasi, in America) and is transmitted by the bite of phlebotomine sand flies. Infected dogs constitute the main domestic reservoir of the parasite and play a key role in transmission to humans, in which the parasite produces visceral leishmaniasis. The increasing awareness that control of the human disease depends on effective control of canine leishmaniasis has promoted, in the last few years, research into leishmanial infection in dogs. Newly available specific reagents and molecular tools have been applied to the detailed investigation of canine leishmaniasis and important advances have been made in elucidating the epidemiology and pathology of the disease. These new findings have led to better understanding of the disease, and have also helped in the development of new diagnostic methods and control measures against the infection, such as insecticide-impregnated collars for dogs, new drugs and treatment protocols, and second generation vaccines, with the hope of not only reducing the heavy burden of the disease among dogs but also reducing the incidence of human visceral leishmaniasis.

Effect of insecticide-impregnated dog collars on incidence of zoonotic visceral leishmaniasis in Iranian children: a matched-cluster randomised trial

BACKGROUND

Deltamethrin-impregnated dog collars reduce sandfly bite rates on dogs, and are effective in killing sandflies that attempt to feed. Because domestic dogs are the principal reservoir hosts of zoonotic visceral leishmaniasis, we tested whether community-wide application of dog collars could protect children against infection with Leishmania infantum, the parasite that causes the disease.

METHODS

18 villages were paired, matched by preintervention child prevalence of L infantum infection. Within pairs, villages were randomly assigned to either control or intervention. All domestic dogs in intervention villages were provided with collars for the transmission season. The main outcome measure was incidence of L infantum infection after 1 year measured by seroconversion. Secondary outcomes were leishmanin skin test (LST) conversion and seroconversion in dogs.

FINDINGS

The seroconversion rate in children was 1.49% (17/1141) in the intervention villages and 2.41% (26/1078) in control villages (odds ratio 0.57, 95% CI 0.36-0.90, p=0.017). LST conversion was also lowered, but not significantly (odds ratio 0.66, 0.41-1.08, p=0.096). The seroconversion rate in dogs in intervention villages was also significantly reduced (0.46, 0.30-0.70, p=0.0003).

INTERPRETATION

Community-wide application of deltamethrin-impregnated dog collars not only protects domestic dogs from L infantum infections, but might also reduce the risk of L infantum infection in children. These dog collars could have a role in control of visceral leishmaniasis and replace controversial dog culling programmes in some countries. However, the effectiveness of dog collars will depend on the importance of wild versus domestic canids as reservoir hosts of L infantum.

Chemotherapy of canine leishmaniosis

Visceral leishmaniosis is a widespread and potentially fatal disease of dogs and humans common in the Mediterranean region, the Middle East, and South America. Canine leishmaniosis is most frequently treated with the drugs meglumine antimoniate, allopurinol, amphotericin B, or a combination of meglumine antimoniate and allopurinol. Therapy with the currently used drugs often achieves temporary clinical improvement and changes in immunologic parameters with restoration of the ability to mount parasite-specific cell mediated responses and decrease in anti-leishmanial antibody titers. However, treatment usually does not prevent relapse of disease or eliminate parasite carriage. Due to the current lack of an ultimate and effective therapy for canine leishmaniosis, new drugs, delivery systems and treatment strategies are necessary to achieve a consistent parasitological cure in infected dogs.

A randomised, blinded, placebo-controlled clinical trial with allopurinol in canine leishmaniosis

A total of 45 non-uremic dogs, with clinical signs indicating leishmaniosis, entered the study. Diagnosis was confirmed by indirect immunofluorescence assay (IFA) on serum and polymerase chain reaction (PCR) on bone marrow samples. The dogs were randomly allocated into Group A (n=37) that received allopurinol (10mg/kg B.W., per os, twice daily) for 4 consecutive months, and Group B (n=8) that were placebo-treated. Clinical signs were scored just before and at monthly intervals throughout the study period, in a blinded and independent fashion. Complete blood count, serum biochemistry profile, urinalysis, lymph node and bone marrow parasitology, IFA and enzyme-linked immunosorbent assay (ELISA) serology and bone marrow PCR were carried out at the beginning and at the end of the trial. A total of three Group A and one Group B dogs died of end stage kidney disease that developed during the trial. In Group A animals that endured the trial there was a significant improvement in the general body condition, conjunctivitis, peripheral lymphadenopathy, splenomegaly, masticatory muscle atrophy, ulcerative stomatitis, epistaxis, exfoliative dermatitis, cutaneous ulcerations, blepharitis and nasodigital hyperkeratosis. The same observation was made for anemia, lymphopenia, hyperproteinemia, hyperglobulinemia, hyperphosphatemia, increased alkaline phosphatase activity and the low albumin/globulin ratio. By contrast, no improvement of any kind was seen in Group B dogs. Lymph node and bone marrow parasite numbers were significantly decreased in Group A animals. In Group B, that occurred only in the lymph nodes. Apart from remission of clinical signs and restoration to normal of clinicopathological abnormalities, allopurinol did not eliminate Leishmania organisms, as the PCR result on bone marrow was still positive in all the dogs that finished the trial.

Topical insecticide treatments to protect dogs from sand fly vectors of leishmaniasis

We compared the susceptibility of sand fly vectors to four topical insecticide treatments applied to domestic dogs, a reservoir of human leishmaniasis. Dogs were exposed to sand flies pretreatment and at 1 week, 1 month, and 2 months posttreatment. Sand fly bloodfeeding and survival rate of both fed and unfed flies were significantly reduced by the permethrin, deltamethrin, and fenthion treatments, but diazinon had no effect. The survival rate of bloodfed sand flies was reduced by up to 86% with deltamethrin collars. The antifeeding effect suggests that deltamethrin collars may be recommended to dog owners to protect their pets from sandfly- borne diseases. The combined effects on sand fly feeding and survival indicate that epidemiologic, community-based trials are warranted to test whether deltamethrin collars could reduce the incidence of canine and, hence, human leishmaniasis.