LEISHMANIA INFANTUM INFECTION IN BENNETT'S WALLABIES (MACROPUS RUFOGRISEUS RUFOGRISEUS) IN A SPANISH WILDLIFE PARK

Is leishmaniasis the new emerging zoonosis in the world?

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

A Systematic Review (1990-2021) of Wild Animals Infected with Zoonotic Leishmania

Leishmaniasis are neglected diseases caused by several species of Leishmania that affect humans and many domestic and wild animals with a worldwide distribution. The objectives of this review are to identify wild animals naturally infected with zoonotic Leishmania species as well as the organs infected, methods employed for detection and percentage of infection. A literature search starting from 1990 was performed following the PRISMA methodology and 161 reports were included. One hundred and eighty-nine species from ten orders (i.e., Carnivora, Chiroptera, Cingulata, Didelphimorphia, Diprotodontia, Lagomorpha, Eulipotyphla, Pilosa, Primates and Rodentia) were reported to be infected, and a few animals were classified only at the genus level. An exhaustive list of species; diagnostic techniques, including PCR targets; infected organs; number of animals explored and percentage of positives are presented. L. infantum infection was described in 98 wild species and L. (Viania) spp. in 52 wild animals, while L. mexicana, L. amazonensis, L. major and L. tropica were described in fewer than 32 animals each. During the last decade, intense research revealed new hosts within Chiroptera and Lagomorpha. Carnivores and rodents were the most relevant hosts for L. infantum and L. (Viannia) spp., with some species showing lesions, although in most of the studies clinical signs were not reported.

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

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

Antibodies elicited by the CaniLeish® vaccine: long-term clinical follow-up study of dogs in Spain

The prevention of canine leishmaniosis in healthy dogs requires a multimodal approach combining repellents with an effective vaccine. A vaccine that modulates the cell-mediated immune response against the protozoan has been available in Europe since 2012 (CaniLeish®, Virbac, France). The aim of the present study was to monitor dogs vaccinated with CaniLeish® to examine the kinetics of the antibody response and the safety and tolerance of CaniLeish®. Dogs vaccinated with CaniLeish® were monitored for 12 months. In follow-up visits at baseline (primovaccination or annual booster) (Visit 1, V1), and 1 (V2), 4 (V3), 8 (V4) and 12 (V5) months later, we examined antibody response kinetics using two serology techniques (IFAT and Speed Leish K™). Tolerance to CaniLeish® and its safety were also monitored. Anti-L. infantum IgG antibodies were determined in 242 dogs (125 dogs after primovaccination (Group P) and 117 dogs after booster vaccination (Group B). In addition, 46, 22 and 19 dogs were followed for 2, 3 and 4 years, respectively. At baseline, 100% of dogs in Group P returned negative IFAT and Speed Leish K™ test results while 9.4% (11/117) in Group B tested IFAT positive though Speed Leish K™ negative. In subsequent visits, seropositivity was detected by IFAT in 31.2% (Group P) and 41% (Group B) of the dogs in V2; 16.8% (Group P) and 10.2% (Group B) in V3; 6.4% (Group P) and 8.5% (Group B) in V4; and 3.2% (Group P) and 5.9% (Group B) in V5. All dogs tested Speed Leish K™ negative except two, in which it was later confirmed by molecular testing that they were not infected. Adverse events that could be associated with the vaccine were detected in 20 out of 314 dogs (6.4%). The good clinical status of all dogs was confirmed in an exhaustive clinical exam and haemato-biochemical profile. The Canileish® vaccine was well-tolerated with exceptions that did not appear to be related to age, sex, race or size of vaccinated dogs. Anti-L. infantum antibodies were detected by IFAT in 31.9-40.3% of the dogs 1 month after vaccination, and these antibodies could still be detected in 3.2% of the dogs 1 year later. This means that veterinarians need to use other tools (eg. PCR) to correctly diagnose seropositive dogs.

Where's wallaby? Using public records and media reports to describe the status of red-necked wallabies in Britain

Investigating the range and population dynamics of introduced species provides insight into species behavior, habitat preferences, and potential of becoming established. Here, we show the current population status of the red-necked wallaby (Notamacropus rufogriseus) in Britain based on records from an eleven-year period (2008-2018). Records were obtained from Local Environmental Records Centres (LERCs), the National Biodiversity Network (NBN), and popular media. All records were mapped and compared to a historical distribution map (1940-2007), derived from published data. A total of 95 confirmed wallaby sightings were recorded between 2008 and 2018, of which 64 came from media sources, 18 from Local Environmental Records Centres (LERCs), seven from the National Biodiversity Network (NBN), and six from the published literature (Yalden, Br. Wildl., 24, 2013, 169). The greatest density of wallaby sightings was in southern England, with the Chiltern Hills Area of Outstanding Natural Beauty a particular hot spot (n = 11). More sightings were recorded in August than in any other month. Much of the species' ecology and responses to British biota and anthropogenic pressures are unknown, and therefore, further research is warranted. The methods used here are widely applicable to other non-native species, particularly those that the public are more likely to report and could be an important supplement to existing studies of conservation and management relevance.

Molecular xenomonitoring and host identification of Leishmania sand fly vectors in a Mediterranean periurban wildlife park

The epidemiological cycle of zoonotic phlebotomine-borne Leishmania infantum is a complex system in which domestic animals and wildlife interact and participate in its maintenance and transmission. In this study, we combined entomological surveillance, xenomonitoring of L. infantum and identification of host feeding sources of engorged females to investigate the potential contribution of a periurban wildlife park to leishmaniosis in neighbouring residential areas. Overall, 7,309 sand flies were collected in 111 trap-days during the summers of 2016-2018 in an endemic area in south-east Spain. Five different sand fly species were captured, with Phlebotomus perniciosus, the main L. infantum vector in this region, representing the most common species. Sand fly distribution was spatially heterogeneous in terms of species, sexes and female physiological stage (unfed, gravid and engorged females) and related to host distribution and management, and environmental features. None of the 602 sand flies analysed for L. infantum infection by kinetoplast real-time PCR were positive. We used molecular tools to identify the vertebrate hosts of sand flies and identified 17 host species, mainly mammals. Human DNA was not identified in engorged sand flies. This study provides evidence that wildlife parks in south-east Spain are ideal grounds for sand fly vectors but do not necessarily increase L. infantum infection risk to humans and dogs living in surrounding residential areas. This is probably because vectors feed mostly on non-L. infantum competent hosts and this should be investigated for a better understanding of the contribution of wildlife parks to the local epidemiology of L. infantum.

Serological and Molecular Findings of Leishmania Infection in Healthy Donkeys (Equus asinus) from a Canine Leishmaniosis Endemic Focus in Tuscany, Italy: A Preliminary Report

Leishmania parasites are considered to be emergent zoonotic pathogens, which is a new concept regarding their epidemiology and the identification of novel animal hosts. The present study is the first in Italy to evaluate anti Leishmania seroprevalence, and the first in Europe to detect parasite DNA in donkeys' blood. The study was performed on jennies living in a Leishmania infantum endemic area of Central Italy. One hundred and ten blood samples were obtained from 67 healthy lactating Amiatina jennies that were semi-extensively reared in Tuscany. When possible, more than one sample was subsequently obtained from the same subject. All samples were processed by immunofluorescence antibody test (IFAT) and by polymerase chain reaction (PCR). For the results, 11 out of 30 animals (36.7%) showed positive scores under IFAT. In addition, 22 out of the other 37 jennies had positive scores, also. The animals showed titers ranging from 40 to 320. Furthermore, 2 subjects that were submitted for 2 and 3 blood samplings, both had more than one positive score. Moreover, 2 seropositive animals were positive for Leishmania DNA. Donkeys are considered to be a preferred source for a sandfly blood meal, even if clinical leishmaniosis has never been reported in Europe for this animal species. In the view of these facts, our preliminary findings would suggest the role of donkey as a potential reservoir for this protozoan agent. Additional studies would be welcome to elucidate the role of the donkey in Leishmania epidemiology of CanL endemic areas and to confirm the preliminary findings and the hypothesis proposed here.

Canine Leishmaniasis: An Overview of the Current Status and Strategies for Control

Canine leishmaniasis (CanL) is a vector-borne disease caused by Leishmania infantum and is transmitted by female phlebotomine sand flies primarily between animals and secondarily to humans. The course of infection may be different from one individual dog to another, ranging from spontaneous cure to acute evolution that leads to death, if proper management and therapy are not adopted. A parasitological cure is rarely achieved and clinical recurrences in CanL are frequent. Vaccination associated with the use of topical insecticides is undoubtedly the most effective form of prevention and control of the disease. In order to integrate the most important scientific knowledge of the literature in one objective publication, this review proposes a short overview of the main points of CanL.

First report of Leishmania infantum infection in the endangered orangutan (Pongo pygmaeus pygmaeus) in Madrid, Spain

Background

Some wild animals have been recognized as potential reservoirs of Leishmania infantum infection (e.g. carnivores, lagomorphs, rodents, etc.). Leishmania infantum was also identified infecting humans and lagomorphs (i.e. hares and rabbits) over the period of 2009–2016, with the latter acting as the main reservoirs involved in the human leishmaniosis outbreak in Madrid.

Results

Two cases of clinical leishmaniosis are reported in orangutans (Pongo pygmaeus pygmaeus) housed at two different centres in Madrid. The first is the case of a 36-year-old male orangutan with severe weight loss and apathy. A complete blood count and biochemical profile revealed anaemia, neutropenia, hypoalbuminaemia and elevated transaminases. Hepato-splenomegaly was also observed. Four months later, due to worsening of clinical signs (mainly bilateral epistaxis), blood and bone marrow samples were collected. Amastigotes of L. infantum were detected in macrophages from a bone marrow aspirate and by specific polymerase chain reaction. The second case was a 34-year-old female orangutan with severe weight loss and apathy and no other apparent clinical signs. A complete blood count and biochemical profile revealed anaemia, pancytopenia and hypoalbuminaemia. Splenomegaly and pericardial effusion were also observed. As leishmaniosis was included in the differential diagnosis, both blood and bone marrow samples were collected. Leishmania infantum infection was confirmed by microscopy, molecular diagnosis and serology (immunofluorescence antibody test). Both animals were treated daily with oral miltefosine for 28 days; allopurinol was also given uninterruptedly in Case 2 for at least 6 months. During follow-up, though good clinical recovery was clear, a lack of parasitological cure was confirmed molecularly in both blood and bone marrow samples from the two orangutans. In both habitats, the presence of the sand fly vector identified as Phlebotomus perniciosus was confirmed.

Conclusions

To our knowledge, this is the first report of L. infantum infection in great apes and in the endangered species P. p. pygmaeus. We are presently looking for L. infantum in other non-human primates living in the same peri-urban areas. If detected, we will examine the impacts of this serious disease on these critically endangered species.

Clinical management of canine leishmaniosis versus human leishmaniasis due to Leishmania infantum: Putting "One Health" principles into practice

The initiative One World, "One Health" tries to rapidly detect emerging or reemerging human and animal infectious diseases and prevent epidemiological situations such as deforestation, some agricultural practices or the appearance of new foci of leishmaniosis due to Leishmania infantum with alternative reservoirs. With this objective in mind, we here consider leishmaniosis in the Mediterranean basin and compare its current clinical management from two perspectives: that of a veterinarian specialized in infectious and parasitic diseases, and that of a physician specialized in infectious tropical diseases. We thus prepared a list of 10 key questions from epidemiology to control of the disease in both species: dogs and humans. This issue requires a concise and clear response to help animal and human health clinicians to improve their clinical management and understanding of this important zoonosis. Our ultimate aim is to update and bring together the information available backed by sound scientific evidence.

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.

Epidemiological role of dogs since the human leishmaniosis outbreak in Madrid

Background

Canine leishmaniosis (CanL) has been in the spotlight since the 2009 outbreak of human leishmaniosis in Madrid. In the framework of the Leishmaniosis Surveillance Programme set up in Madrid, this study examines Leishmania-specific seroprevalences in stray dogs for the outbreak area and rest of the Madrid region over the period spanning from the outbreak to the present (2009–2016). These data are of interest because stray dogs could be sentinels for disease surveillance in endemic areas. Since 2011, we have also been monitoring owned dogs in the outbreak area.

Methods

Over the study period, Leishmania infantum seroprevalence was determined in 2,123 stray dogs from the outbreak and non-outbreak areas. A serological study was also performed for owned dogs in the outbreak area: high-risk dogs such as hunting or farm dogs (n = 1,722) and pets (n = 1372). All dogs were examined and blood was collected. The variables recorded for each animal were: breed, age, sex, and clinical history indicating if the animal was healthy or clinically suspected of having any disease, and if they showed a clinical picture compatible with CanL.

Results

Seroprevalences of L. infantum in stray dogs were similar in the two areas examined: 4.7% (20 out of 346) in the outbreak area and 5.4% (96 out of 1,777) in the remaining Madrid region (χ² = 0.080, P = 0.777). A significant association was found between seroprevalence and age (z = -6.319; P < 0.001). Seroprevalence in owned dogs in the outbreak area was 2.1% in high-risk dogs (37 out of 1,722) and 1.2% in pets (17 out of 1,372) (χ² = 3.561, P = 0.0591).

Conclusions

Both stray and owned dogs do not seem to play an important role in maintaining the transmission cycle of L. infantum in the Madrid outbreak area. The stable seroprevalence of infection observed in sentinel dogs suggests the good clinical management and prevention of CanL by local practitioners in owned dogs.