Manuela Rodrigues

Use of a leishmanin skin test in the detection of canine Leishmania-specific cellular immunity

The leishmanin skin test was used to detect Leishmania-specific cellular immunity in asymptomatic dogs from an endemic region of visceral leishmaniosis. The test was safe since no clinical signs of intolerance to leishmanin were detected during 1 month, in 14 dogs after inoculations of 3 x 10(8) promastigotes/ml. In another group of four dogs no cross reactivity was found after inoculations of a PPD which demonstrated the specificity of the test. In the same group of animals, repeatability was assessed by repeated inoculations of leishmanin at 1-5-month intervals and the threshold of sensitivity was the concentration of 3 x 10(6) promastigotes/ml. Secondly, we applied the test in a dog population that live in an endemic region of visceral leishmaniosis and found a significant increase in Leishmania-infected dogs after the application of this test in the field.

Serological survey of Toxoplasma gondii infection in domestic cats from northeastern Portugal

Cats are very important hosts in the epidemiological cycle of Toxoplasma gondii, a zoonotic protozoan parasite that can infect humans and many other animal species worldwide. We report a serological survey of antibodies to T. gondii in domestic cats from northeastern Portugal, by means of the modified agglutination test. Three cats had titres of 20 (3.9%), 18 had titres of 40 (23.7%) and 55 animals had titres of > or =800 (72.4%). Results of three seropositive kittens with less than 4 months were not considered for determining the seroprevalence of infection, which was found to be 35.8% (73/204). Differences in the seroprevalence levels were not statistically significant between males (35.6%) and females (36.0%) or pure non-European (26.7%) and European or mixed-breed cats (39.6%). Animals aged 36-71 months and 72-180 months had the highest seroprevalences of infection, i.e. 51.7% and 51.2%, respectively, which significantly differ from the values observed in cats with 2-11 months (14.6%) and 12-35 months (26.3%). Infection levels were also significantly different between cats that lived totally indoors (7.7%) and those that had access to outdoors (45.4%), as well as between cats living alone (13.8%) and those that had contact with other cats (39.4%). Seroprevalence values in cats fed only commercial canned or dried food (22.9%) and animals whose diet included raw or undercooked viscera and/or meat (53.5%) were also significantly different. Furthermore, considering only 108 cats, differences of seropositivity to T. gondii were significant between feline immunodeficiency virus infected and non-infected animals, but this was not observed for feline leukaemia virus. Age, habitat and diet were identified as risk factors for the feline T. gondii infection by logistic regression analysis. Some control measures are suggested based on these findings.

Seroprevalence of Toxoplasma gondii infection in cattle, sheep, goats and pigs from the North of Portugal for human consumption

Prevalence of antibodies to Toxoplasma gondii and risk factors associated with infection were assessed in food animals from the North of Portugal for human consumption. Antibodies were assayed by means of the modified agglutination test with a cut-off titre of 100 for cattle, and 20 for sheep, goats, and pigs; 7.5% of 161 cattle, 33.6% of 119 sheep, 18.5% of 184 goats, and 9.8% of 254 pigs were seropositive. Among the risk factors examined animal age was an important risk factor for seropositivity to T. gondii. The consumption of raw or undercooked meat should be regarded as an important source of infection to people in the study area.

High seroprevalence of antibodies to Toxoplasma gondii in wild animals from Portugal

We report an investigation of antibodies to Toxoplasma gondii in 52 wild birds and 20 wild mammals from northern and central areas of Portugal by using the modified agglutination test. The birds comprised 26 common buzzards (Buteo buteo), five tawny owls (Strix aluco), four white storks (Ceconia ceconia), three Eurasian eagle owls (Bubo bubo), three northern goshawks (Accipiter gentilis), two booted eagles (Hieraaetus pennatus), two common barn owls (Tyto alba), two Eurasian sparrowhawks (Accipiter nisus), two short-toed eagles (Circaetus gallicus), one black kite (Milvus migrans), one Griffin vulture (Gyps fulvus), and one peregrine falcon (Falco peregrinus). The mammals were eight wild boars (Sus scrofa), six red foxes (Vulpes vulpes), two common genets (Genetta genetta), two European badgers (Meles meles), one European roe deer (Capreolus capreolus), and one Iberian wolf (Canis lupus signatus). Fifty percent of the wild birds and 90% of the wild mammals were seropositive; the overall seroprevalence of infection was 61.1%. When comparing the prevalence of antibodies in birds and mammals from northern Portugal, a significant difference was found, but the same was not true for birds and mammals from central Portugal. Seroprevalence levels were 30.0% in juvenile and 62.5% in adult birds (p = 0.046), 0.0% in juvenile and 94.7% in adult mammals (p = 0.100), 80.0% in female and 66.7% in male birds (p = 1.000), and 81.8% in female and 100% in male mammals (p = 0.479). This is the first study performed on T. gondii in birds of prey, white storks, and wild carnivores in Portugal.

Seroepidemiology of Toxoplasma gondii infection in women from the North of Portugal in their childbearing years.

Seroprevalence of Toxoplasma gondii infection and associated risk factors were investigated in 401 women of childbearing age from the North of Portugal. Of the 98 (24·4%) seropositive women, 92 (93·9%) only had immunoglobulin (Ig)G, two (2·0%) only had IgM, and four (4·1%) others had both IgG and IgM. Risk factors for T. gondii infection in women were: engaging in soil-related activities without gloves [odds ratio (OR) 8·4], consumption of unwashed raw vegetables or fruit (OR 7·6), and consumption of smoked or cured (non-cooked) processed pork products (OR 2·5). Most women of childbearing age from the North Portugal are susceptible to primary infection with T. gondii and, therefore, the risk of congenital toxoplasmosis remains high.

Identification of antibodies to Leishmania silent information regulatory 2 (SIR2) protein homologue during canine natural infections: pathological implications

Dogs are the domestic reservoir of zoonotic visceral Leishmaniasis caused by Leishmania infantum in the Mediterranean basin and thus constitute an important health problem in both human and veterinary medicine. Until vaccines become available, conventional measures such as epidemiological surveillance including reservoir control will be among the practical options for prevention and containment of the disease. We have recently characterised novel Leishmania sp. genes encoding parasite proteins named (LmS3a: homologous to mammalian ribosomal protein S3a; LmSIR2: homologous to the silent information regulatory 2 protein family; LimTXNPx: homologous to the peroxiredoxin family with N-terminal mitochondrial leader sequence) that may contribute to the host immune dysfunction in murine experimental Leishmaniasis. In the present study we have investigated the humoral responses against the parasite antigens in groups of L. infantum-infected dogs with different clinical status: symptomatic and asymptomatic with DTH positive or negative test. The determination of immunoglobulin (Ig) isotypes revealed high levels of total IgG in both symptomatic and asymptomatic animals when compared to IgM. Furthermore, the IgG2 appeared to be the predominant subclass of Ig present in the sera of infected animals particularly in the case of symptomatic dogs. The IgG subclass reactivity analysis revealed a broad specific recognition range of parasite recombinant antigens. Interestingly, differential profiles of IgG1 and IgG2 antibody reactivity were observed in asymptomatic and symptomatic dogs. The LmSIR2 protein was found to be a highly reactive molecule with IgG2 from most of the asymptomatic and symptomatic animals. Considering the fact that LmSIR2 secreted by the parasites can be bound and taken up by neighbouring cells, the latter could be a target for anti-LmSIR2 antibodies and this may contribute to the immunopathological alterations and host tissue damage. The implications of these observations in the pathogenesis of Leishmaniasis are discussed.

Leishmania infantum MON-98: infection in a dog from Alto Douro, Portugal

We report the isolation of Leishmania infantum zymodeme MON-98 in Portugal, its first known occurrence outside the focus of El Agamy, Egypt. One dog found to be infected with Acanthocheilonema dracunculoides during a survey of canine filariosis in the Alto Douro region, north-east Portugal, was also discovered to have Leishmania in bone marrow. The isolated strain was identified by isoenzyme analysis. A search for other possible cases of L. infantum MON-98 infection in dogs, vectors and particularly humans is necessary to establish the real epidemiological importance of this zymodeme in the endemic region of Alto Douro.

Development of a Dipstick Assay for Detection of Leishmania-Specific Canine Antibodies

ABSTRACT A dipstick assay, based on Leishmania infantum antigen, for the rapid detection of Leishmania-specific antibodies in canine serum samples was developed and evaluated. After determination of optimal dipstick test conditions, test performance was compared with two existing serological tests, i.e., the direct agglutination test (DAT) and the fast agglutination screening test (FAST). In the present study the dipstick test had a sensitivity of 99.2% and a specificity of 87.9%. The DAT had a sensitivity of 97.7% and a specificity of 95.2%, whereas the FAST had also a sensitivity of 97.7% and a specificity of 93.0%. High degrees of agreement were observed between the dipstick test and DAT (93.7%; κ value, 0.86), between the dipstick test and FAST (91.8%; κ value, 0.82), and between the DAT and FAST (95.2%; κ value, 0.90). The high sensitivity and ease of performance make the dipstick test very suitable for surveillance surveys.

Opisthorchis felineus in cat: case report

Opisthorchis felineus foi encontrado em um gato admitido no Hospital Veterinario da Universidade de Tras-os-Montes e Alto Douro. No momento de admissao, o animal apresentava-se em estado de choque, com hipotermia, desidratacao e mucosas palidas. As analises hematologicas revelaram linfopenia, eosinofilia e anemia moderada. A necropsia observou-se distensao da vesicula biliar e intensa infestacao parasitaria no figado. O estudo morfologico do parasita revelou tratar-se de Opisthorchis felineus.