Although the dog is the main reservoir, other animals such as hares and rabbits, goats, rodents, cats, even birds, can be effective reservoirs, and may therefore be involved in the transmission of leishmaniasis. Control in these animal populations is important to prevent their role as active reservoirs.
These animals do not directly spread the disease, it is always through the phlebotome vector, so it is important to protect themselves from bites by avoiding passing from dusk and in the early hours of the night, and at dawn, or using appropriate protective clothing and personal use repellents
Leishmaniosis in leporids (hares and rabbits)
Although it has been described that other animals, besides the dog, may be infected with Leishmania Its epidemiological relevance is generally very limited. However, in recent years it has been shown that in certain circumstances secondary reservoirs may have a prominent role in the origin of human leishmaniasis outbreaks. This has been the case of the outbreak of the Community of Madrid in which a new cycle of jungle transmission has been described in which in leporids they have acted as the main reservoirs and origin of the disease in humans, including for their demonstration studies of xenodiagnostic, serology and molecular characterization.
Leishmaniosis outbreak in the southwest of the Community of Madrid
In 2009, alarms went off when there was an increase in cases declared in the southwest zone of the CM, encompassing four municipalities close to each other (Fuenlabrada, Leganés, Getafe and Humanes de Madrid), with which the largest outbreak of leishmaniosis began declared in Europe. This remains active, having affected, from July 2009 to date, more than 690 people (38% affected by visceral leishmaniasis and 62% by cutaneous) (Arce et al.,).
It was found that the increase in human cases did not correlate with an increase in canine leishmaniasis and this fact suggested that it could be due to the appearance of new reservoirs: the hare and the rabbit. As for these new reservoirs, it is already known that both the hare and the rabbit are capable of transmitting Leishmania to the sandfly, as evidenced by the xenodiagnostic studies conducted in both species. The highest density of hares in the area of the outbreak (caused by urban changes in previous years and absence of natural predators) and the seroprevalence found in them (74.1% positive and of these, 31.8% with titles greater than 1 / 400 according to Moreno et al., 2013 suggest that the hare was the most important reservoir in the CM outbreak.The rabbit, also involved, would contribute to a lesser extent to maintain the infection.In both species, in addition, the presence of Leishmania DNA in spleen and skin samples using specific PCR techniques, and different studies have demonstrated the presence of Lesihmania in rabbits and hares outside this area of the outbreak both in the Community of Madrid and in other areas of Spain , which suggests that in certain epidemiological circumstances they could lead to new outbreaks (García et al., 2014, Ruiz-Fons et al.,).
The species causing the outbreak was L. infantum, specifically the ITS-LOMBARDI genotype. He drew attention that 70% of human cases corresponded to immunocompetent people, between 40 and 60 years of age, which made us suspect that we were facing a more virulent strain of L. infantum. The ex vivo virulence analysis of two isolates (BOS1FL1 and POL2FL7) from the area of the outbreak showed that it was significantly greater than the characteristic virulence of the strain commonly isolated in the CM since 1992.
Regarding the vector, the majority species in the area of the outbreak and the only one from which it has been isolated Leishmania is P. perniciosus, although the presence of Sergentomyia diminuta and P. ariasi. The density of P. perniciosus increased considerably during the outbreak, reaching 143 sandflies / m2 in 2012 when before the average was 30 sandflies / m2. The prevalence of L. infantum in P. perniciosus collected in the area of the outbreak was 58.5% according to Jimenez et al., 2013, which highlights the high transmission rate of Leishmania existing then. The vector also showed preferences when feeding. When blood was taken from inside the sandflies, 60% came from hares, 30% from humans and 10% from cats.
In hares and rabbits, leishmaniasis occurs asymptomatically without causing injury, as is the case in most wild reservoirs.
There have been many teams of health and administration professionals who have dedicated their efforts to ending the escalation of human cases and advancing the knowledge of the vector, the reservoirs, the parasite itself and the relationship between them. With the data updated to October 2016, a downward trend in the number of cases can be seen from 2012 to the present.
In addition to the scientific advances mentioned above, a series of actions have been carried out to control the progress of the infection. A control plan for both the reservoir and the vector was implemented, apart from environmental measures, managed by the Administration in collaboration with the Town Halls and with the support of different centers (Carlos III Health Institute, VISAVET, Faculty of Veterinary Medicine and Faculty of Biological Sciences, among others).
The actions carried out were:
- About the reservoir: control of the populations of hares and rabbits in the affected area, in addition to closing the vivariums where the rabbits are protected. Animal surveillance was intensified by serological (IFI) and molecular (PCR) techniques to detect the circulation of Leishmania in these animal populations. In addition to promoting different lines of research.
- About the vector: a program of disinsection at risk points (landfills, sewers, etc.) and surveillance by means of the collection of specimens through adhesive and light traps for sandflies, has also been investigating the infection of the female sandfly by Leishmania and of feeding study to know the type of reservoir from which they take the blood.
- Environmental control: sanitation measures have been applied at risk points (clearing, sewer network cleaning, garbage and debris cleaning, sludge disposal, etc.). The collection of abandoned animals was also intensified.
- Communication and education: in addition to the reinforcement of surveillance, communication of the situation was promoted to professionals in the health system and recommendations were sent to individuals. Different technical documents, posters, information leaflets, online information, etc. have been prepared. and scientific sessions have been held.
Very common in dogs, leishmaniasis was considered a very strange pathology in the cat, due to its natural resistance and the effective response of the immune system to the disease. But, at present it is observed that its incidence is increasing in a worrying way. Depending on the area of the Iberian Peninsula, from 1.7% to 60% of the cats studied may be affected. It seems that there is a greater chance of getting the disease in cats suffering from other diseases, which reduce the effectiveness of the immune system, such as feline immunodeficiency or toxoplasmosis.
Symptoms of feline leishmaniasis
Leishsmaniosis in the cat is a disease with a long incubation period (it takes a long time to manifest symptoms) and once they develop, they are quite nonspecific. In the cat the disease can study in three different ways:
- Cutaneous form. Painless subcutaneous nodules are observed, especially located in the head and neck. In addition, these symptoms of feline leishmaniasis are usually accompanied by an increase in the size of nearby lymph nodes. Also, these ganglia can subsequently be opened and ulcerated. Other skin symptoms can be observed.
Eye shape. The eyes are affected, observing conjunctivitis, blepharitis (inflammation of the eyelids), uveitis (inflammation of the uvea), peri-orbicular alopecia (hair loss around the eyes), etc.
Diagnosis of feline leishmaniasis
The disease is diagnosed by specific tests, such as blood test, with a test that searches and quantifies the antibodies generated by the animal in the presence of the protozoan. It is not possible to make a symptomatic diagnosis, because the symptoms are very nonspecific.
Treatment of feline leishmaniasis
In leishmaniasis, both in humans and in dogs and cats, there are two strategies when it comes to treatment. On the one hand, there is preventive treatment and, on the other, curative treatment once the disease is diagnosed.
- He preventive treatment against feline leishmaniasis It consists of avoiding contact with the mosquito. For this, physical barriers are used (for example, putting mosquito nets on the windows) or using different insectic>
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Leishmaniosis in cats, a dangerous disease
Cats with leishmaniasis have signs, such as lesions on the skin, mucous membranes and eyes
Immunosuppressed cats, or with low defenses, usually have a higher risk of developing leishmaniosis, experts explain. Probably, the immune system of a healthy cat is able to control the infection caused by the protozoan or parasite Leishmania infantum, either because it eliminates it or because it is dormant in your body.
"It is likely that only genetically predisposed cats, with an immune system weakened by a viral disease, receiving treatments with immunosuppressive products or suffering from tumors develop the disease," explains Imanol Sagarzazu, veterinarian.
The leishmaniosis is a parasitic disease and endemic in the Mediterranean area. In Spain it is presented with greater incidence in the southern and central areas. The Cantabrian cornice has less favorable conditions for the development of the vector insect, so there is a lower incidence.
Leishmaniasis in cats, transmitted by a mosquito
The reason is that the phlebotome, a disease-transmitting insect, is active with certain environmental conditions: warm or temperate temperatures and a certain degree of humidity, conditions that mostly take place in Spain during the period between April and October.
The feline population of endemic areas for leishmaniasis is usually infected through parasite-transmitting mosquitoes. Leishmania. However, "only a small part of these cats develop the disease and have clinical signs, such as skin ulcers," says Sagarzazu.
Leishmaniosis in cats and their clinical signs
Cats with leishmaniasis usually have several types of clinical signs, such as lesions on the skin, mucous membranes or eyes, ulcers and scabs, explains Xavier Roura, veterinarian of the Hospital Clínic Veterinari, of the Autonomous University of Barcelona, and member of a platform to prevent leishmaniasis in cats and dogs.
Visceral clinical signs of leishmaniasis in cats are less common, and affect organs such as the liver and kidneys. A common injury, Roura adds, are the nodules that form under the cat's skin. These nodules usually appear on the eyelids or ears, and are not painful, although they can also occur on any other part of the feline's body, such as paw pads.
Other less common signs of cats suffering from leishmaniasis are lack of appetite or anorexia, as well as decay, fatigue and apathy.
Cats with leishmaniosis: data
"The number of cats affected by leishmaniasis has increased in the last ten years," says Roura. Although in Spain there is no conclusive data on the number of feline population affected by the disease, there are genetic studies in this regard.
According to the area of Spain where the sampling is done, the percentage of cats affected by the leishmania, may vary between 0.5% and 28%. The autonomous community with the largest number of felines affected by the disease is the Andalusian, compared to other regions, such as the Basque Country, where the cases of cats with leishmaniasis are almost anecdotal.
Treatment and prevention of leishmaniosis in cats
A cat with leishmaniasis needs periodic checks to detect possible disease regrowths
A feline that has developed the disease needs a specific veterinary treatment against the parasite and for the clinical signs triggered by the leishmania. Once these disappear, it is necessary to carry out periodic controls to the animal to detect regrowths of the disease.
A cat's defenses with leishmaniasis require special care. You have to keep your immune system as active as possible to avoid relapses. To achieve this, it is key to ensure that you do not get sick from other pathologies, as in the case of a cold or gastroenteritis, which can leave the cat's defenses and the door open to a reappearance of the clinical signs of leishmaniasis.
The preventive methods against the bite of the phlebotome insect They are key to avoiding leishmaniasis, especially in the case of cats that live in high-risk areas, such as the Mediterranean basin. Pipette, collar and aerosols are formats in which methods to protect felines from this insect are marketed. However, the choice of the product must be supervised by the veterinarian, in order to guarantee both the efficacy of the antiparasitic and the health of the animal.
A preventive method against recent leishmaniasis is the vaccine against this disease. However, the feline version of this preventive method does not yet exist and, for now, can only be applied to dogs.
Can leishmaniasis in cats be spread to people?
Is there a risk of infection for people living with cats infected by Leishmania? The probability of this is low, because the disease transmitter is the phlebotome insect and not the cat, which is only the host of the protozoan (Leishmania) that causes the disease.
A healthy person with an effective immune system would not be affected by the disease. On the contrary, if the person is immunocompromised, they may be more likely to develop leishmaniasis.
Clinical signs and diagnosis
Verde, A. OrtГєГ ± ez, S. Villanueva, M. Pardo
1. Veterinary Faculty Zaragoza, Animal Pathology. Diagnostic Service Clinical Immunopathology Animals Company. [email protected]
2. Vilazoo Veterinary Center, Santa Margalida, Mallorca
Images courtesy of the authors
Feline leishmaniasis (LFel), the result of the natural infection of cats by the parasite Leishmania infantum, was first diagnosed in the world in Algeria in 1912 (Sergent et al., 1912). However, while numerous patients with canine leishmaniasis (Lcan) have been registered over these one hundred years, the number of cases described in cats has been much smaller.
In Spain, the first clinical description of an LFel was made in 1933. In all of Europe, from 1989 to 2014 only 59 cases have been described.
The estimated seropositivity rates in our country are very variable (from 1.7 to 60%) (Sainz A, 2011), since they depend on factors such as:
- The geographical area.
- The technique used.
- The cut-off point or lintel.
- The diagnostic performance of the technique.
- The type of habitat of cats (indoor or outdoor-free).
- The season of the year in which the samples were obtained (higher incidence and prevalence in samples taken in periods of activity of the vector according to some authors).
But, in general, the seropositivity values for LFel are lower than those of Lcan for the same endemic geographical area.
Cats that live in endemic areas are usually exposed to being infected by the parasite, but most feline pets live indoors, so the risk of exposure decreases considerably.
In Spain, as in the rest of Europe, L. infantum it is to date the only kind of Leishmania Isolated in cats. There is no genetic or phenotypic difference between strains isolated in dogs and those isolated in the feline species, with MON-1 zymodema being the most frequent (Pennisi and Solano, 2013a).
LFel is a disease transmitted to cats throughout Europe by Phlebotomus spp. That is, the same vector that transmits LCan and human leishmaniosis (LHum). In turn, it has already been demonstrated by xenodiagnostics that Phlebotomus get infected by L. infantum after feeding on blood from naturally infected cats (Maroli et al., 2007). It remains to clarify the role that cats (alternative reservoir to dogs versus accidental hosts) can play in the epidemiology of leishmaniasis in endemic areas.
Of all the studies on seroprevalence of LFel carried out in the last ten years in Spain (Table 1), the most recent one was developed in Madrid analyzing by IFI technique 346 stray cats (MirГі et al., 2014). The results provide a seroprevalence of 3.2% (11/346). But no positive cat could be found using the PCR technique in any of the blood samples. On the other hand, of the 11 HIV-positive IFI cats, three were also positive for IVF, six to Toxoplasma gondii and none to FeLV. So it seems that cats infected by Toxoplasma, and to a lesser extent HIV-positive IVF, are more likely to be infected by L infantum.
Although some recent publications (Pennisi et al., 2013b) state that epidemiological investigations would indicate that feline infection by L. infantum It could be underestimated in endemic areas, nor have any clinical case been described or known in our geographical area (middle valley of the Ebro), which is endemic and that, however, in the canine species has a variable prevalence , ranging between 2.6% and 20% (Peris et al., 2011).
Since in 2007 Maroli showed that Phlebotomus they could be competent vectors for the transmission of infection in the cat when ingesting blood from infected animals has increased the concern to determine if the cats with whom we live may or may not harbor the parasite and what this may mean in the face of Public Health . In endemic areas there may be infected cats, but only a very small part of these animals develop the disease. It is very likely that the cat's immune system will be able to control the infection of this parasite, either by eliminating it or by keeping it in a chronic subclinical state. Only in a minority of cats, probably with compromised immune system, the disease progresses and clinical signs appear.
There are no studies on the pathogenesis of LFel, nor on the immune response in infection by L. infantum in cats It is known that antibody titers rise within two weeks of experimental inoculation (IV or SC) of the parasite, but no clinical signs appear in experimental infections nor clear biopathological abnormalities are detected as in the canine species (Pennisi et al., 2013a).
LFel should be included in the lists of differential diagnoses of various processes that present with clinical signs similar to the clinical patterns described below.
The cutaneous form of the LFel
It is the most frequent and should be taken into account in the differential diagnosis of nodular dermatitis, erosive-ulcerative and allopathic. Clinically, skin and mucocutaneous lesions can be observed.
One of the most frequent cutaneous presentations is nodular dermatitis, characterized by painless subcutaneous dermal nodules and predominantly located in the head (truffle, beautiful, ears, eyelids) (Figure 1), and on the front and back legs (bearings), but they can appear anywhere on the body (Navarro et al., 2010).
|Figure 1. Subcutaneous dermal nodules by L. infantum.|
Erosive-ulcerative dermatitis is characterized by ulcerative-crusted lesions located on the head, face and neck (ears, truffle, lower jaw and eyelids), on plantar pads (figure 2) or with bilateral symmetrical distribution in carpus, elbows, tarsus or ischial tuberosity.
|Figure 2. Erosive-ulcerative lesions on plantar pads of a cat infected by L. infantum.|
There have also been described nodular-ulcerative lesions in the mucous membranes, mucocutaneous lesions in the beautiful, tongue (figure 3) eyelids and nostrils, and vesicles and hemorrhagic nodules located on the head (edge of the truffle and edge of the ears).
|Figure 3. Mucocutaneous nodules in the tongue of a cat infected by L. infantum.|
Other cutaneous pictures, very rare, include allopathic forms, squamous dermatitis, miliary dermatitis and papular dermatitis. Itching of varying intensity is a rare sign that only appears in less than a third of cases with cutaneous symptomatology.
The ocular forms are also very frequent, having been described from granulomatous blepharitis, conjunctivitis and keratitis, to monolateral uveitis (which is the most frequent ocular lesion) and can evolve into panophthalmitis.
Generalized systemic forms
The widespread spread of the parasite, resulting in a visceral systemic picture, is a clinical presentation of little presentation in cats. But in those affected clinical cases it can involve lesions in the spleen, liver, kidneys and lymph nodes. Regional or generalized lymphadenopathy can be observed, which appears in a high percentage of cases. Among the most frequent systemic signs are asthenia and anorexia.
To establish the diagnosis in a suspicious cat, it must be carried out comprehensively, including numerous tests.
- Cytological examination of samples from skin lesions, mucous membranes and enlarged lymph nodes.
- Blood smear and bone marrow.
- Cutaneous biopsy for conventional staining (H&E) and immunohistochemistry.
- Quantification of the antileishmania antibodies with serological techniques developed in the cat. In the case of high suspicion and low or even seronegative antibody titers it is advisable to perform molecular techniques to rule out the disease.
It is important to consider that the use of serology as a test of confirmation of the infection could underestimate the diagnosis of leishmaniasis. On the other hand, we must not forget that it is highly probable that there is an underlying or concurrent disease (IVF, FeLV, allergies, autoimmune processes, toxoplasmosis, neoplasms, metabolic diseases), therefore basic laboratory tests, including blood count, biochemistry, should be performed , urinalysis and serum proteinogram.
Biopathological abnormalities such as normocytic anemia, moderate to severe normochromic anemia, monocytosis, neutrophilia, lymphopenia or pancytopenia, elevated urea and creatinine, elevated phosphorus, and altered proteinogram with hyperglobulinemia may occur.
However, some of the biopathological alterations such as pancytopenia may correspond to abnormalities dependent on other concurrent pathologies (IVF, FeLV) or, in general, a state of immunological compromise.
It is performed for direct confirmation of the presence of amastigotes in skin samples, lymph nodes, bone marrow or any other affected tissue (such as conjunctival nodules and in aqueous humor).
IFI, ELISA, DAT, WB, HAI. Of all of them ELISA is the most sensitive (Penissi et al., 2013).
Biopsy with hematoxylin-eosin staining (H&E) and immunohistochemical technique. In the conventional histology of cutaneous lesions we can find nodular to diffuse dermatitis, histiocytic with intracytoplasmic microorganisms, or a superficial and deep diffuse granulomatous pattern, with attachment in some cases. Patterns of dermatitis of the lichenoid interface associated with epidermal hyperplasia, multifocal spongiosis and orthokeratotic hyperkeratosis have also been described.
In general, different levels of hyperkeratosis and hyperplasia appear in the epidermis with ulcerated foci. To visualize the presence of amastigotes inside macrophages, it will often be necessary to perform specific immunhystochemical staining against L. infantum.
Qualitative PCR or quantitative PCR can be performed. As in the canine species, the PCR performed on lymph node samples is more sensitive than in blood.
Treatment and prevention
There are no studies, in the feline species, nor on what is the treatment of choice, nor of the half-life, nor of the pharmacokinetics of the allopurinol and n-methyl-meglumine drugs. Nor is there data with sufficient scientific evidence on what the best therapeutic protocol in LFel may be.
From what was published, it could be inferred that the best results are obtained by administering allopurinol at a dose of 10 mg / kg / 12 h or 20 mg / kg / 24 h, until clinical cure. In some cases n-methyl-meglumine at a dose of 5 mg / kg / 24 h or 25 mg / cat / 24 h, for one month. The combination of allopurinol with n-methyl-meglumine is not recommended due to toxicity problems. There are no data on the use of miltefosine in cats.
The prognosis is reserved and any underlying process or situation that may be compromising the immune system must be controlled.
No other preventive measures are available other than avoiding exposure to vectors, since permethrin-based repellents are toxic to cats. There is also no experience for the use of immunomodulators or vaccines in the feline species.
- In the endemic areas of Lcan, the diagnosis of cats with suspicious clinical signs should be investigated.
- Although the role of cats in the epidemiology of leishmaniasis is not known, it can be considered as a reservoir of much less importance than the dog.
- There is not a good correlation between the clinical symptoms and the positive results with the serological techniques. It is advisable to use complementary diagnostic methods to establish the definitive diagnosis.
- As for the available serological techniques, ELISA and IFI are the most used, but cats seem to develop a humoral response much weaker than dogs.
- There is no scientific evidence to support the use of a certain treatment.
- Chatzis MK et al. Vet Parasitol. 2014, 202 (3-4): 217.
- Maroli M et al. Vet Parasitol. 2007, 145: 357.
- MirГі G et al. Parasit Vectors.2014, 24 (7): 112.
- Navarro JAm et al. J Comp Path. 2010, 143: 297.
- OrtuÃ ± ez A et al. SEVC Poster. 2010
- Pennisi MG et al. J Fel Med Sug. 2013 (b), 15 (7): 638.
- Pennisi MG and Solano L. Ed. Servet. 2013 (a), pp 185.
- Sainz A. Proceedings. FC- AVEPA. 2011, pp.
- Sergent ED et al. Bulletin of the Society of Pathologie Exotique. 1912, 5:93.
- Peris A. Seroepidemiological study of the dynamics of infection of Leishmania infantum in canine populations of the middle valley of the Ebro. Univ. Doctoral Thesis Zaragoza, 2011.