Francesca Mancianti

Studies on canine leishmaniasis control. 1. Evolution of infection of different clinical forms of canine leishmaniasis following antimonial treatment

81 dogs naturally infected with Leishmania infantum in the Isle of Elba, Italy, were treated with meglumine antimoniate (Glucantime). 36 of them (45.5%) were asymptomatic cases. 4-24 months after treatment the dogs were clinically and serologically examined; the recovery rates were 47.2% for asymptomatic cases, 33.3% for oligosymptomatic cases, and 11.1% for symptomatic cases. Furthermore, treatment had prevented the development of patent disease in 90% of non-recovered asymptomatic cases, whereas it had produced only slight improvement of clinical condition in patent dogs which were still infected after drug administration. Treatment with antimonial drugs is therefore recommended in canine leishmaniasis control if non-patent or sub-clinical forms of the disease are detected by seroepidemiological surveys.

Feline leishmaniosis due to Leishmania infantum in Italy

A case of leishmaniosis in domestic cats (Felis catus domesticus) is described. The subject showed a nodular lesion on the eyelid. The diagnosis was achieved by serological, parasitological, and light and electron microscopic investigations. By molecular techniques the aetiological agent was identified as belonging to Leishmania infantum, the species implicated in human and canine leishmaniosis in southern Europe. A preliminary study on the prevalence of asymptomatic feline leishmaniosis, performed in the areas where the infected cat was identified, revealed a low seroprevalence of infection: only 1 (0.9%) of the 110 cat sera examined by indirect fluorescent antibody test was positive for anti-Leishmania antibodies. Because clinical signs in feline leishmaniosis are unspecific and similar to those observed in other diseases commonly found in this species, leishmaniosis must be added to the differential diagnosis by feline veterinary practitioners and adequate serologic and histopathologic investigations must be performed in endemic areas.

RENAL INVOLVEMENT IN CANINE LEISHMANIASIS - A LIGHT-MICROSCOPIC, IMMUNOHISTOCHEMICAL AND ELECTRON-MICROSCOPIC STUDY

In a prospective survey in the Isle of Elba, 413 dogs affected by naturally acquired Leishmania infantum infection were identified out of a controlled population of 1,500 resident mongrel dogs. In all the 34 randomly selected dogs of different breed, age, and duration of disease, the presence of glomerular lesions which defined mainly two categories of glomerulonephritis (GN) was observed. The first group was characterized by mesangial-cell proliferation either with focal features (11 dogs), or with a diffuse pattern (10 dogs). The second group (12 dogs) showed the typical findings of segmental membrano-proliferative GN; amyloid deposits were seen in the glomerular tuft and interstitium in 1 dog. Immunohistochemical investigation revealed granular deposits of IgG, IgM, and C3 both in mesangial areas as well as on glomerular capillary walls. Granular immune deposits om the tubular basement membrane were also found in 31 out of 34 dogs examined. With ultrastructural investigation, subendothelial and mesangial electron-dense deposits were revealed. Age, sex, serum creatinine, BUN, duration of disease, anti-Leishmania antibody titers, and immune complexes did not discriminate between the types of observed GN, while proteinuria did. The study shows that the renal involvement is the natural sequela in dogs infected with L. infantum, and that the kidney lesions are characterized by immunologically mediated glomerular and tubular damage.

Comparison between an enzyme-linked immunosorbent assay using a detergent-soluble Leishmania infantum antigen and indirect immunofluorescence for the diagnosis of canine leishmaniosis

Serum samples collected from 290 dogs--186 Leishmania-infected and 104 control animals--were screened to detect the presence of specific antibodies to Leishmania infantum antigens in Tuscany, Italy. Two different techniques were compared: an indirect immunofluorescence assay (IFA) and an indirect enzyme-linked immunosorbent assay (ELISA). The ELISA was developed using a detergent-soluble antigen of L. infantum promastigotes. Triton X-100 and protease inhibitors were used as detergent and to increase reproducibility of the assay, respectively. A strong correlation between the anti-Leishmania antibody levels obtained by ELISA and those obtained using IFA was observed. The ELISA appeared to be somewhat more sensitive than IFA (99.5% vs. 98.4%), while its specificity was lower (97.1% vs. 100%), even if not significantly different. Immunoblotting analysis, using the detergent-soluble L. infantum antigen, demonstrated that proteins of M(r) 30 and 73 kDa were recognized by all positive sera, regardless of the serum titre. Furthermore, antigens of M(r) 16, 18, 26, 33, 50 and 117 kDa were also frequently reactive with a large proportion of sera from infected dogs. This ELISA demonstrated a high sensitivity and specificity as well as the IFA, and it seems to be a suitable assay for large scale epidemiological studies.

Evaluation of dot enzyme-linked immunosorbent assay (dot-ELISA) for the serodiagnosis of canine leishmaniosis as compared with indirect immunofluorescence assay

A dot enzyme-linked immunosorbent assay (dot-ELISA) was developed and compared with a standard indirect immunofluorescence assay (IFA) for the rapid serodiagnosis of canine leishmaniosis. The two tests were used to examine sera from Leishmania infantum-infected and control dogs. Using the dot-ELISA, 137 of 149 sera (91.9%) from infected animals gave a clearly positive reaction, whereas in the standard IFA technique 147 (98.7%) were positive at a reciprocal titer of 40 or over (titer range 40-10,240). Control sera from 75 healthy dogs, not living in endemic areas, and 11 dogs with other diseases (babesiosis, cryptococcosis, ehrlichiosis, dermatitis, and chronic hepatitis) but Leishmania-negative were used to determine the specificity of the assays. All the sera were negative with IFA (100%), whereas using the dot-ELISA only 74 sera (86%) from controls gave a negative result. In the standard IFA no cross-reactivity was noted, in the dot-ELISA a weak cross-reaction was observed with a serum sample from a dog with babesiosis. The interpretation of dot-ELISA could be easily performed by visual inspection of the nitrocellulose disks. The most remarkable feature of dot-ELISA was the high sensitivity (91.9%) and positive predictive value (92.6%), even if the test showed a specificity lower than IFA. Because of its easy performance and high sensitivity, the dot-ELISA may be a useful test to be executed in the field for the diagnosis of canine leishmaniosis.

Dermatophytes isolated from symptomatic dogs and cats in Tuscany, Italy during a 15-year-period

Between January, 1, 1986 and December, 31, 2000, dermatological specimens from 10.678 animals (7.650 cats and 3.028 dogs) were examined for dermatophytes. All the animals presented clinical signs of ringworm. Two thousand-four hundred fifty-six of the 10.678 (23%) examined animals scored positive for dermatophytes, 566 out of 3.028 canine (18.7%) and 1890 out of 7.650 feline specimens (24.7%). Microsporum canis constituted 83% and 97% of the isolated dermatophytes respectively in dogs and cats, M. gypseum represented 13% and 2.6% and T. mentagrophytes 5.5% and 0.2%. A sexual predisposition for mycotic infections was not observed. The animals with less than 1 year of age were more frequently infected. Canine toy breeds showed a significantly higher (P < 0.001) prevalence of infections by M. canis. Microsporum gypseum was mostly recorded from sporting (hunting) breeds [such as T. mentagrophytes (6.7%)]. Microsporum canis was isolated from long-haired cats with a ratio of 2:1 versus short-haired cats, while M. gypseum and T. mentagrophytes were never recovered from Persian cats. The annual distribution of the infections in dogs showed a significantly higher incidence for M. gypseum in summer versus winter and spring, while the recovery rate of M. canis from cats was very significantly higher in fall and winter than in summer and spring. Trichophyton mentagrophytes did not show a similar seasonal distribution.

Environmental detection of Microsporum canis arthrospores in the households of infected cats and dogs

Microsporum canis is the dermatophyte most frequently recovered from canine and feline ringworm cases. The household environment can be contaminated both by symptomatic animals and through asymptomatic M canis carriage, resulting in a potential human health risk. The load of M canis arthrospores was determined in households harbouring infected pets, in order to evaluate the infectivity of the animals versus the environment. The environments inhabited by 30 symptomatic animals (21 cats and 9 dogs) infected by M canis were examined by sampling both surfaces and indoor air. The surfaces were examined by means of contact plates; the air sampling was performed with a Sas super-100 AIR SAMPLER (PBI, Italy). Environmental contamination was detected in all households with cats, while only four out of nine houses harbouring dogs were found positive. The frequence of isolation in each sampling, and the results in terms of colony forming units per plate in the different houses appeared to be quite homogeneous. Heavily infected environments harboured kittens only. Infected owners were observed in eight households, in all of which at least one infected cat was present. No history of human dermatophytosis in households harbouring dogs was found. On the basis of our results, infected cats appear to cause substantial environmental contamination, and provoke a substantial presence of viable airborne fungal elements. Dogs seem to be of lower importance in the spread of M canis: they contaminated surfaces, but they never contaminated the air. The results of this study confirm the potential leading role of the feline species in the environmental spread of M canis.

Mycological findings in feline immunodeficiency virus-infected cats

Thirty-five FIV-seropositive cats and 55 FIV-seronegative matched cats were examined for yeasts (oropharyngeal swabs) and dermatophytes (hair brushings). The frequency of isolation of Candida albicans and Cryptococcus neoformans was significantly higher in the former group. The only dermatophyte isolated was Microsporum canis. Its prevalence was three times higher among FIV-infected cats than among control animals.

Studies on canine leishmaniasis control. 2. Effectiveness of control measures against canine leishmaniasis in the Isle of Elba, Italy☆

A serological and parasitological survey carried out in 1985 in the Isle of Elba, Italy, revealed a high prevalence of canine leishmaniasis. This focus was considered ideal for the evaluation of effectiveness of treating infected dogs with meglumine antimoniate, applied as a control measure during 1985 and 1986. New data on prevalence were obtained for the years 1986 and 1987. Incidence of new canine leishmaniasis cases after the transmission seasons 1984, 1985 and 1986 were determined by examining 2 cohorts: cohort I, dogs born within 2 transmission seasons, and cohort II, adult dogs examined and found to be negative before each transmission season. Over 2000 tests were carried out on 1500 dogs. Prevalence analysis showed a reduction of infective dogs (symptomatic and oligosymptomatic) from 14.4% in 1985 to 5.2% in 1987. Incidence analysis showed a decrease of new cases from 12.4% after transmission season 1984 to 4.6% after transmission season 1987. The results indicate a two-thirds reduction of the disease frequency in dogs of the Isle of Elba after a 2-year period of control measures.

Dermatophytes and Keratinophilic Fungi in Cats and Dogs Dermatophyten und keratinophile Pilze bei Katzen und Hunden

Summary: During an 11 month period from January to November 1987, dermatophytes and keratinophilic fungi were isolated from 70 (75 %) of 93 cats and 62 (36.9 %) of 168 dogs.