Parasitological, serological and molecular diagnosis of Dirofilaria immitis in dogs in Northeastern Brazil.

Dirofilaria immitis is a zoonotic filarid that mainly affects the domestic dog, causing a generally fatal chronic disease, known as heart worm disease. In addition to dogs, the parasite can affect wild canids, cats, and humans. Due to its importance to One Health, detection of parasitism by D. immitis in dogs can help the adoption of control measures that aim to reduce the occurrence of parasitosis in animals and humans. The detection of D. immitis is based on the use of parasitological, serological, and molecular methods, which vary in sensitivity and specificity. Therefore, the objective was to evaluate and compare the efficiency and performance of parasitological, serological, and molecular tests in the detection of D. immitis in dogs in Northeastern Brazil. Whole blood and serum from 140 dogs from the municipality of Sousa were used, varying between males and females; aged one to 17 years; pure and mixed breeds; domiciled and stray. Three microscopic parasitological techniques (MPT) were used: capillary blood smear (CBS), peripheral (PBS) and modified Knott test (MK) associated with the morphometric diagnosis of the microfilariae. For the detection of D. immitis antigens, a rapid immunochromatographic test (RIT) (ALERE Dirofilariose AG Teste kit®, Seogu-dong, Korea) was used, and polymerase chain reaction (PCR) as a molecular method. To evaluate the tests, PCR was considered the gold standard, and sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) values were calculated. To verify the agreement of the tests, the Kappa test was performed (p ≤ 0.05). From the 140 analyzed samples, 33.6% (48/140) presented microfilariae, antigen and/or parasitic DNA. 23.6% (33/140) were positive in the CBS; 25.7% (36/140) in the PBS; 29.3% (41/140) in the MK; 30% (42/140) in the RIT and 28.6% (40/140) in the PCR. All methods showed almost perfect agreement with PCR, high sensitivity (0.8-0.95), specificity (0.94-0.99), and values established with VPP (0.8571-0.9722) and VPN (0.9519-0.9797). The CBS and PBS showed less sensitivity and greater specificity. MK presented the highest sensitivity and RIT was the choice for hidden infections. Considering the occurrence of D. immitis in dogs in a non-coastal region of Northeastern Brazil, an epidemiological approach is recommended to identify risk factors for this zoonotic parasitosis.

High rate of feline immunodeficiency virus infection in cats in the Brazilian semiarid region: Occurrence, associated factors and coinfection with Toxoplasma gondii and feline leukemia virus.

To evaluate the occurrence of feline immunodeficiency virus (FIV) and factors associated with this and to demonstrate occurrences of coinfection with Toxoplasma gondii and feline leukemia virus (FeLV) in cats, a total of 103 blood samples were collected from owned cats, during home visits. To diagnose FIV and FeLV, immunochromatographic kit was used and serological diagnoses of T. gondii, the indirect immunofluorescence test was performed. The occurrence of FIV-seropositive cats was 23.3% (24/103) and the factor associated with infection was male sex. T. gondii seropositivity of 53.4% (55/103) was observed and 75% of FIV cases (18/24) were positive for T. gondii coinfection. Only 0.9% (1/103) was positive for FeLV. It can be concluded that the seroprevalence of FIV in cats in the Brazilian semiarid region is high and that FIV positive cats were also likely to be T. gondii seropositive, while FeLV had very low occurrence in the study region.

Vertical transmission of Toxoplasma gondii in naturally infected ewes in the semiarid region of Brazil.

To evaluate transplacental transmission of Toxoplasma gondii in naturally infected ewes, blood samples were collected from 55 pregnant ewes and their offspring, before ingestion of colostrum. From 16 offspring of positive ewes and nine offspring from negative ewes, blood samples were obtained after 48 h and 7, 14, 21, 28, 35, 42, 49 and 56 days after birth. T. gondii antibodies were detected in serum samples using the indirect fluorescence antibody test (IFAT ≥ 64). Four of the 30 positive ewes (13.3 %) had offspring positive for T. gondii before ingesting colostrum (vertical transmission). The colostrum antibody titers decreased every week, and only 20 % (2/10) of the lambs in continued to present detectable antibody titers until day 56 after birth. Therefore, vertical transmission of T. gondii in lambs was indication of occur and is an important route for transferring and maintaining the agent in sheep herds in the Brazilian semiarid region.