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Arquivo Brasileiro de Medicina Veterinária e Zootecnia

Print version ISSN 0102-0935On-line version ISSN 1678-4162

Arq. Bras. Med. Vet. Zootec. vol.59 no.1 Belo Horizonte Feb. 2007

http://dx.doi.org/10.1590/S0102-09352007000100014 

VETERINARY MEDICINE

 

Amastigota forms resembling Leishmania sp. on corneal ulceration in a dog: case report

 

Formas amastigotas compatíveis com Leishmania sp. em ulceração corneal de cão: relato de caso

 

 

F.L.C. BritoI; L.C. AlvesI; F.C.L. MaiaI; A.R. AlbuquerqueI; J.P.D. OrtizII; J.L. LausII

IDepartamento de Medicina Veterinária, UFRPE – Recife, PE
IIFaculdade de Ciências Agrárias e Veterinárias – UNESP Via de Acesso Prof. Paulo Donato Castellane, s/n 14884-900 – Jaboticabal, SP

 

 


ABSTRACT

One dog with visceral leishmaniasis is reported presenting cutaneous lesions, cachexia, and corneal ulceration. Parasitological and serological diagnoses were performed by exam of contents of the aspirative punction of the bone marrow and by immunofluorecence, respectively. Amastigota forms resembling Leishmania sp. were visualized by citology.

Keywords: dog, ulceration corneal, Leishmania sp., ophthalmology


RESUMO

Relata-se o caso de um cão com leishmaniose visceral apresentando lesões cutâneas, caquexia e úlcera de córnea. Realizou-se o diagnóstico parasitológico e sorológico por meio de exame do material da medula óssea e por imunofluorescência indireta, respectivamente. À citologia da úlcera corneana, visibilizaram-se formas amastigotas compatíveis com Leishmania sp.

Palavras-chave: cão, úlcera de córnea, Leishmania sp., oftalmologia


 

 

INTRODUCTION

In Brazil, canine visceral leishmaniasis is also known as canine calazar and it is a potentially lethal zoonosis caused by a protozooan, a macrophages intracellular parasite from the Leishmania (Leishmania) chagasi species (Feitosa et al., 2000).

Dogs affected by visceral leishmaniasis usually develop the systemic form of the disease showing a great range of clinical signs (Noli, 1999). Ocular manifestations have been described in canine leishmaniasis affecting over 50% of the infected animals (Brito et al., 2006). Canine calazar affects mostly the anterior segment of the eye (Puchol ad Gonzalez, 1989).

Corneal limited involvement is seldom observed. Keratitis associated to conjunctival and uveal inflammation is often observed (Roze, 1986). Nevertheless, corneal exclusively pathologies, such as superficial and stromal keratitis and descementocele may be observed in dogs with canine calazar (Molleda et al., 1993; Roze, 2002).

There are a great number of studies about canine leishmaniasis pathogeny and lesions, although very few reported in detail the ocular lesions due to this disease (Garcia-Alonso et al., 1998).

 

CASE REPORT

A seven year-old German shepherd male dog was referred to the veterinary hospital at the Universidade Federal Rural de Pernambuco, Brazil, with clinical suspicion of canine visceral leishmaniasis. At clinical examination, cachexia and cutaneous lesions were observed. Ophthalmic examination revealed photophobia, blepharospasm, neovascularization and discrete corneal edema. Erosion of the corneal epithelium was observed in the right eye. The corneal ulceration was confirmed after the fluorescein test (Fig. 1). Anterior chamber, uveal tract, lens, vitreo and retina were normal in both eyes. Following the diagnosis, treatment was performed using antibiotic therapy (Tobramicina® eye drops1 at regular intervals of 6 hours for 15 days and condroitin sulfato (Dunason® eye drops1) at regular intervals of 8 hours over the same period. No improvement was observed following this medical treatment which demanded a revaluation. Since the animal came from an endemic region, cytology of the wounded area was performed. Anesthetic eye drops (AnestalconÒ eye drops1) was instilled previously the cytology. Soon after, the cytology of the corneal area was proceeded avoiding the contact with the conjunctive. The material obtained from the ulcer was stained by the fast staining technique and evaluated using an optic microscopy at a 1000x magnification. The analyses demonstrated the presence of epithelial cells, polimorphonuclears, red blood cells and also structures resembling amastigota forms of Leishmania sp. (Fig. 2 and 3). Meanwhile, it was performed the aspiration of the bone marrow in which amastigota forms of Leishmania sp. were observed. Indirect immunofluorescence was also performed and a seropositive reaction was observed in a 1:640 titer.

 

 

 

 

 

 

DISCUSSION

Canine visceral leishmaniasis is a chronic disease associated with varied clinical signs. Due to the diversity of clinical presentation; the disease may be difficult to diagnosis. Ocular alterations have been reported in some studies, as being common in dogs infected by Leishmania infantum and L. chagasi, such as uveitis and conjunctivitis (Peña et al., 2000; Brito et al., 2006). The ophthalmic form of this disease involving the cornea is less frequent, unless other ocular structures be involved (Roze, 2002).

Despite the very few reports and the low frequency in which isolated corneal involvement occurs in animals affected by visceral leishmaniasis, similar lesions to those reported by this study were described in dogs with ocular disease secondary to leishmaniasis (Roze, 1986). Deep corneal ulceration was reported in dogs and in one cat affected by visceral leishmaniasis (Roze, 2002; Leiva et al., 2002).

Ophthalmic reevaluation and corneal ulcer cytology in this case were due to the lack of success on previous treatment, since uncomplicated superficial clinical ulcers normally heal in a few days (Whitley and Gilger, 2003).

Corneal ulceration can be related to various factors. Fungi, bacteria and parasites may also induce corneal enzymatic degradation. Normally lesions get worse due to neutrophils quimiotatic action, which release lithic enzymes as they degranulate in the stroma (Gordon et al., 1980).

The mechanism which explains the presence of amastigota forms of Leishmania sp. in ocular tissues is unknown (Garcia-Alonso et al., 1996), although some admit that the parasites are carried to the cornea by antigen presenting cells (Saint-André Marchal et al., 1997). The main mononuclear cell population present at the ocular surfaces is represented by the Langerhans cells, especially at the conjuntival and corneal tissues (Wu and Zhang, 1991; Bielory, 2000). These cells have an important role at the ocular surface immunity (Gillette et al., 1982). Because macrophages, dendritic cells and Langerhans cells are the main APCs over Leishmaniasis (Ferrer et al., 1988), it is easy to understand the involvement of the immunogenic mechanisms on the ocular surface in events of CVL.

Antigenic stimulation and lymphocyte T migration leads to local antibodies production which probably achieve the cornea by diffusion. Presence of activated T lymphocyte at the cornea acts on antibody production by the secretion of the B cells growing factor. At the same time plasmocytes unchain an increase on total immunoglobulin levels. Therefore, in canine visceral leishmaniasis the response to immunoglobulins is significatively high, being deleterious instead of protective, permitting clinical signs to appear (Abbas et al., 1995; Noli, 1999). It is admitted that the lesion of the corneal epithelium in this case is connected to immune mediated events.

In similar corneal ulceration in stromal keratitis caused by type 1 simple herpesvirus it is proposed that the response be mediated by virus-specific T limphocytes of the delayed hypersensibility type promoted by the Langerhans cells just like the immunogenic responses unchained by visceral leishmaniasis (McLeish et al., 1989).

The presence of Leishmania has been described in the conjunctival ocular of dogs naturally infected (Laugier and Verro-Baoulanger, 1992). Therefore, the care should be taken in the procedure of the corneal cytology, for also not raising lesion of the conjunctive and, consequently, contamination of the material by conjunctival cells.

The literature consulted did not report studies showing the amastigota forms of Leishmania sp. at corneal cytology, except when from the nodules at cornea or limbus. Therefore, this is the first case that the authors describe the superficial ulcerative keratitis in which structures resembling amastigota forms of Leishmania sp. are isolated from the wounded area.

 

CONCLUSIONS

It is important to highlight that the ophthalmic signs in dogs are being correlated to visceral leishmaniasis, especially at the anterior segment of the eye. Therefore, in endemic areas where corneal affections non responsive to the conventional treatment is present, canine visceral leishmaniasis with ocular manifestations must be considered as a differential diagnosis. In the future, studies including a larger number of animals are necessary to elucidate the presence of the parasite in the area of the lesion.

 

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Recebido em 23 de outubro de 2004
Aceito em 20 de setembro de 2006

 

 

E-mail: fabiobrito@click21.com.br
1 Alcon – São Paulo, Brazil

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