SOARES, L. A.; http://lattes.cnpq.br/1346408953529450; SOARES, Laynaslan Abreu.
Resumo:
Dirofilaria immitis is a zoonotic parasite that mainly affects domestic dogs, and wild canids
and occasionally other mammals such as domestic cats and humans. This dissertation consists
of two chapters in the form of scientific articles. In chapter 1, the objective was to determine
the prevalence and factors associated with infection by D. immitis in dogs in the city of Sousa,
semiarid of Paraíba. 320 dogs were selected and evaluated, of which 160 were domiciled and
160 stray, from 32 neighborhoods in the city of Sousa. Clinical examination, blood collection
and epidemiological data of each animal were performed. For microfilariae research, three
methods were performed: capillary blood smear (ESC), peripheral (ESP) and modified Knotttest
(KM), associated with the morphometric diagnosis of the microfilariae. There was a
prevalence of 17.5% (56/320) positive animals for D. immitis, with 71.43% (40/56) wandering
and 28.57% (16/56) domiciled. Of the 32 neighborhoods evaluated, 24 were found positive
dogs, with Angelim and Doutor Zezé, the neighborhoods with the highest percentage 1.56%
(5/320) each. The categories of cardiac disorders (Odds ratio 6,231 [CI 1,539-25,236]) and stray
dogs (Odds ratio 2,463 [CI 1,281-4,735]) were risk factors for infection. Of the 56 positive
animals, 28 showed positivity in the three tests, and another 28 showed variation between
methods and / or between made slides. It was considered that the region of the Sertão Paraibano
has a significant prevalence of infection by D. immitis, being necessary to establish forms of
control and prophylaxis, to reduce the risks of transmission to animals, as well as to humans.
In Chapter 2, the objective was to evaluate and compare the efficiency and performance of
parasitological, serological and molecular tests in the diagnosis of D. immitis in the Sertão
Paraibano, Northeast Brazil. Whole blood and serum from 140 dogs from the municipality of
Sousa were used. Three microscopic parasitological techniques (PMS) were used: ESC, ESP
and KM, associated with the morphometric diagnosis of microfilariae. For the detection of D.
immitis antigens, the rapid immunochromatographic test (TRI) of ALERE Dirofilariose AG
Teste kit® was used, and direct polymerase chain reaction (PCR) as a molecular method. To
evaluate the tests, PCR was considered the gold standard, with sensitivity, specificity, positive
predictive value (PPV) and negative predictive value (NPV) values being calculated. To verify
the agreement of the tests, the Kappa test was performed (p≤0.05). Of the 140 samples analyzed,
33.6% (48/140) presented microfilariae, antigen and / or parasitic DNA. Of this total of samples,
23.6% (33/140) were positive in the ESC; 25.7% (36/140) in the ESP; 29.3% (41/140) in the
KM; 30% (42/140) in the TRI and 28.6% (40/100) in the PCR. All methods showed almost
perfect agreement with PCR, high sensitivity (0.8 to 0.95), specificity (0.94 to 0.99), values
established with VPP (0.8571 to 0.9722) and VPN (0.9519 to 0.7979). All techniques were
highly effective with almost perfect agreement with PCR. ESC and ESP were the techniques
with less sensitivity and greater specificity. KM was considered the most sensitive test and IRT
was the choice for hidden infections. The PCR showed high sensitivity and specificity in
comparison to the other tests, and better identification of D. immitis.