Evaluation of the accuracy of parasitological techniques for the diagnosis of intestinal parasites in cats

Avaliação da acurácia de técnicas parasitológicos para o diagnóstico de parasitos intestinais em gatos

Hanstter Hallison Alves Rezende Juliana Boaventura Avelar Heloísa Ribeiro Storchilo Marina Clare Vinaud Ana Maria de Castro About the authors

Abstract

The accuracy of the parasitological techniques of Willis, Hoffman-Pons-Janer or Lutz (HPLJ), Sheather and Faust was evaluated in fecal samples from stray cats caught by the Zoonosis Control Center in Goiânia, Goiás, Brazil. These four techniques were applied separately to analyze 154 fecal samples, and their accuracy was analyzed based on an evaluation of their sensitivity, specificity, positive and negative predictive values, and Kappa index, resulting in the selection of the Willis technique as the nominal gold standard. Of the 154 samples, 115 (74.68%) tested positive for intestinal parasites. The analysis of the frequency of positivity indicated that the HPLJ technique detected 86.1% of the positive samples and was the closest to the gold standard. The analysis of the accuracy of the techniques was evaluated using the most prevalent parasites. The Sheather technique showed the highest accuracy in the detection of Ancylostomatidae, while the Sheather and HPLJ techniques showed similar accuracies in the detection of Cystoisospora spp. when compared to the gold standard. Lastly, the Faust technique showed the highest accuracy in the detection of Toxoplasma gondii when compared to the gold standard. This study underscores the importance of combining parasitological techniques in the diagnosis of intestinal parasites in cats.

Keywords:
Accuracy; intestinal parasites; parasitological techniques; stray cats

Resumo

A avaliação da acurácia das técnicas parasitológicas de Willis, Hoffman-Pons-Janer ou Lutz (HPJL), Sheather e Faust foram realizadas em amostras fecais de gatos capturados pelo Centro de Controle de Zoonoses em Goiânia, Goiás. Essas quatro técnicas foram utilizadas separadamente para análise de 154 amostras fecais. A análise de acurácia foi empregada, avaliando-se a sensibilidade, especificidade, valor preditivo positivo, valor preditivo negativo e índice kappa, sendo a técnica de Willis eleita como padrão-ouro. Das amostras analisadas 74,68% (115/154) foram positivas para enteroparasitos. A análise de frequência de positividade demonstrou que a técnica HPJL detectou 86,1% dos positivos, aproximando-se do padrão-ouro. A avaliação da acurácia foi realizada pela análise dos parasitos mais prevalentes, sendo que, para Ancilostomídeos, a técnica de Sheather apresentou melhor acurácia; para Cystoisospora spp., as técnicas de Sheather e HPJL foram semelhantes e para Toxoplasma gondii, a técnica de Faust apresentou melhor acurácia comparada ao padrão ouro. Este estudo demonstra a importância da associação de técnicas parasitológicas para o diagnóstico de enteroparasitos em gatos.

Palavras-chave:
Acurácia; enteroparasitos; técnicas parasitológicas; gatos errantes

Introduction

Cats play an important role in the transmission of zoonotic agents, especially of heteroxenous parasites that may infect humans, leading to important public health diseases such as cutaneous larva migrans, visceral larva migrans, toxoplasmosis, giardiasis and cryptosporidiosis, among others (SCHANTZ, 1991Schantz PM. Parasitic zoonoses in perspective. Int J Parasitol 1991; 21(2): 161-170. http://dx.doi.org/10.1016/0020-7519(91)90006-S. PMid:1869350.
http://dx.doi.org/10.1016/0020-7519(91)9...
; MCCARTHY & MOORE, 2000McCarthy J, Moore TA. Emerging helminth zoonoses. Int J Parasitol 2000; 30(12-13): 1351-1360. http://dx.doi.org/10.1016/S0020-7519(00)00122-3. PMid:11113260.
http://dx.doi.org/10.1016/S0020-7519(00)...
; SERRA et al., 2003Serra CMB, Uchôa CMA, Coimbra RA. Exame parasitológico de fezes de gatos (Felis catus domesticus) domiciliados e errantes da Região Metropolitana do Rio de Janeiro, Brasil. Rev Soc Bras Med Trop 2003; 36(3): 331-334. http://dx.doi.org/10.1590/S0037-86822003000300003. PMid:12908032.
http://dx.doi.org/10.1590/S0037-86822003...
). Several diagnostic techniques have been used in order to identify the different parasite stages, thus providing a more reliable diagnosis. The techniques most commonly employed are: zinc sulfate centrifugal flotation (Faust), flotation in saturated sodium chloride solution (Willis), spontaneous sedimentation (Hoffman-Pons-Janer-Lutz), and the formol ether concentration technique (DE CARLI, 2001De Carli GA. Colheita e preservação da amostra fecal. In: De Carli GA. Parasitologia clínica: seleção de métodos e técnicas de laboratório para o diagnóstico das parasitoses humanas. São Paulo: Editora Atheneu; 2001. p. 3-26.; DE CARLI & OLIVEIRA, 2001De Carli GA, Oliveira OLM. Controle de qualidade em parasitologia clínica. In: De Carli GA. Parasitologia clínica: seleção de métodos e técnicas de laboratório para o diagnóstico das parasitoses humanas. São Paulo: Editora Atheneu; 2001. p. 577-610.; MARIANO et al., 2005Mariano MLM, Carvalho SMS, Mariano APM, Assunção FR, Carzola IM. Uma nova opção para diagnóstico parasitológico: Método de Mariano e Carvalho. NewsLab 2005; 68: 132-140.; MACHADO et al., 2008Machado ER, Santos DS, Costa-Cruz JM. Enteroparasites and commensal among children in four peripheral districts of Uberlândia, State of Minas Gerais. Rev Soc Bras Med Trop 2008; 41(6): 581-585. http://dx.doi.org/10.1590/S0037-86822008000600007. PMid:19142436.
http://dx.doi.org/10.1590/S0037-86822008...
).

Numerous clinical and veterinary diagnostic laboratories seek a parasitological methodology that combines specificity, sensitivity, speed and low operational cost. A correctly performed parasitology stool test enables the identification of the etiological agent responsible for the disease, the parasite burden, effective treatment and follow-up. It can also be used in epidemiological surveys as a guideline for the adoption of local prophylactic measures, and as an indication of the quality of population health. Therefore, this test is an extremely important component of human and veterinary medicine practices (VAZ, 2001Vaz AJ. Diagnóstico imunológico das parasitoses. In: De Carli AG. Parasitologia clínica: seleção de métodos e técnicas de laboratório para o diagnóstico das parasitoses humanas. São Paulo: Editora Atheneu; 2001. p. 505-540.; MENDES et al., 2005Mendes CR, Teixeira ATLS, Pereira RAT, Dias LCS. Estudo comparativo entre os métodos de Kato-Kazt e coprotest. Rev Soc Bras Med Trop 2005; 38(2): 178-180. http://dx.doi.org/10.1590/S0037-86822005000200010. PMid:15821795.
http://dx.doi.org/10.1590/S0037-86822005...
; TOSATO et al., 2005Tosato MEVB, Pilonetto M, Scarin AK. Apuração de custos para a realização de urocultura em um laboratório de médio porte do setor privado. NewsLab 2005; 12(69): 114-142.; MACHADO et al., 2008Machado ER, Santos DS, Costa-Cruz JM. Enteroparasites and commensal among children in four peripheral districts of Uberlândia, State of Minas Gerais. Rev Soc Bras Med Trop 2008; 41(6): 581-585. http://dx.doi.org/10.1590/S0037-86822008000600007. PMid:19142436.
http://dx.doi.org/10.1590/S0037-86822008...
).

The parasitological method most routinely employed is the Hoffman-Pons-Janer or Lutz (HPJL) technique, which has the advantage of requiring minimal materials and financial resources, but the disadvantage of involving large amounts of fecal debris from each sample, which hinders the microscopic analysis of the material. Hence, combining different parasitological techniques is useful for the correct identification of different species of parasites and improves the diagnostic accuracy (FLANAGAN, 1992Flanagan PA. - diagnosis, clinical course and epidemiology. A review. GiardiaEpidemiol Infect 1992; 109(1): 1-22. PMid:1499664.; TASCA, 2001Tasca T. Incidência de enteroparasitos na cidade mais fria do Brasil: São José dos Ausentes, Rio Grande do Sul. Rev Brasil Anal Clin 2001; 33(1): 10-20.).

The purpose of this study was to assess the accuracy of different parasitological stool test methods for the detection of intestinal parasites, with emphasis on the detection of T. gondii oocysts.

Materials and Methods

Study

This study was approved by the Animal Ethics Committee (CEUA) of the Federal University of Goiás, under Protocol no. 054/2013).

One hundred and fifty-four fecal samples were obtained from stray cats captured by the Zoonosis Control Center of Goiânia, GO. The samples were placed in sterile universal fecal collectors and refrigerated until processing at the Laboratory of Host-Parasite Relationship Studies (LAERPH) of the Institute of Tropical Pathology and Public Health at the Federal University of Goiás.

Analysis of samples

Various parasitological techniques were employed to identify cysts and oocysts of protozoan parasites, eggs and larvae of parasitic helminths in the feces of stray cats. These techniques were flotation in a saturated sucrose solution, density 1.2 g/mL (SHEATHER, 1923Sheather AL. The detection of intestinal protozoa and mange parasites by a floatation technique. J Comp Pathol Ther 1923; 36: 266-275. http://dx.doi.org/10.1016/S0368-1742(23)80052-2.
http://dx.doi.org/10.1016/S0368-1742(23)...
), spontaneous sedimentation (HOFFMAN et al., 1934Hoffman WA, Pons JA, Janer JL. The sedimentation concentration method in schistosomiasis mansoni. PR J Public Health Trop Med 1934; 9: 283-291.; LUTZ, 1919Lutz AOO. Schistosoma mansoni e a schistosomatose segundo observações, feitas no Brazil. Mem Inst Oswaldo Cruz 1919; 11(1): 121-155. http://dx.doi.org/10.1590/S0074-02761919000100006.
http://dx.doi.org/10.1590/S0074-02761919...
), zinc sulfate centrifugal flotation density 1.18 g/mL (FAUST et al., 1938Faust EC, D’Antoni JS, Odom V, Miller MJ, Peres C, Sawitz W, et al. A critical study of clinical laboratory technics for the diagnosis of protozoan cysts and helminth eggs in feces. Am J Trop Med Hyg 1938; 18(2): 169-183.), and flotation in saturated sodium chloride solution density 1.2 g/mL (WILLIS, 1921Willis HHA. A simple levitation method for the detection of hookworm ova. Med J Aust 1921; 8: 375-376.). The Willis technique was elected as the gold standard in this study due to its ability to detect helminth eggs and larvae and coccidian oocysts, especially T. gondii oocysts.

Statistical analysis

The prevalence of intestinal parasites, the frequency of positivity for each parasite and for each technique were evaluated. To evaluate the diagnostic tests, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and Kappa index (K) of each technique were compared with the gold standard (Willis technique). The parasitological results were analyzed using Epi Info 3.2.1 software (CDC, 2015Centers for Disease Control and Prevention – CDC. Epi Info [online]. Atlanta: CDC; 2015 [cited 2015 Feb 12]. Available from: http://wwwn.cdc.gov/epiinfo/
http://wwwn.cdc.gov/epiinfo/...
).

Results and Discussion

Among the 154 analyzed fecal samples, 74.68% (115/154) were positive for intestinal parasites (Table 1).

Table 1
Frequency of intestinal parasites in fecal samples from stray cats captured by the Center of Control of Zoonosis, in the year of 2012, from Goiania, Goiás, Brazil.

Associations were observad between Ancylostomatidae and T. gondii (8 cases), Ancylostomatidae and Cystoisospora sp. (23 cases), T. gondii and Cystoisospora sp. (4 cases), Ancylostomatidae, T. gondii and Cystoisospora sp. (5 cases), Ancylostomatidae, Cystoisospora sp. and Giardia sp. (1 case) and Ancylostomatidae, Cystoisospora sp. and T. cati (1 case).

The frequency of positivity of each technique was analyzed, based on the 115 positive samples. The Willis technique detected 97.4% (112/115) of the positive samples and presented three false negative results. The HPLJ technique detected 86.1% (99/115) of the positive samples and was the closest to the gold standard, followed by the Sheather technique, which detected 79.1% (91/115). The technique with the lowest frequency of positivity was Faust, with 73% (84/115). Even the gold standard was not able to detect 100% of the positive samples, which reinforces the need to use more than one diagnostic technique. The association of various diagnostic techniques with different principles favors the identification of a greater number of parasitic structures, thus increasing the diagnostic efficacy (SANTOS & CASTRO, 2006Santos SV, Castro JM. Ocorrência de agentes parasitários com potencial zoonótico de transmissão em fezes de cães domiciliados no município de Guarulhos, SP. Rev Arq Inst Biol 2006; 73(2): 255-257.). This study confirmed that using a combination of the gold standard technique (Willis) and the HPJL method, which is the technique most widely employed in diagnostic laboratories, increases the diagnostic efficiency.

The accuracy of the techniques was analyzed based on the parasites that showed the highest frequency, i.e., Ancylostomatidae, Cystoisospora sp. and T. gondii. Thus, in the detection of Ancylostomatidae eggs, the accuracy of the HPLJ, Faust and Sheather techniques was analyzed in comparison to that of the Willis technique (gold standard). This analysis revealed that the Sheather technique presented the highest accuracy, showing 81.1% of sensitivity and 98.4% of specificity, a PPV of 98.6% and NPV of 78.8%, and a k index in good agreement with that of the gold standard (Table 2).

Table 2
Evaluation of the accuracy of the Sheather, Faust and Hoffman-Pons-Janer-Lutz techniques compared to the Willis technique (golden standard), for the diagnosis of Ancylostomatidae.

Cerqueira et al. (2007)Cerqueira EJL, Arcanjo MS, Alcântara LM. Análise comparativa da sensibilidade da técnica de Willis, no diagnóstico parasitológico da Ancilostomíase. Diálogos de Ciência 2007; 5: 1-7. compared the efficiency of the Willis technique to that of the HPLJ method and found that the latter was more sensitive for the diagnosis of Ancylostomatidae. In our study, the HPLJ technique showed good agreement with the gold standard, with k = 0.689. However, the accuracy of the Sheather technique was higher than that of the HPLJ technique for the diagnosis of Ancylostomatidae, because these parasites have light eggs that are more easily detected by flotation with density differences of the Sheather technique (SHEATHER, 1923Sheather AL. The detection of intestinal protozoa and mange parasites by a floatation technique. J Comp Pathol Ther 1923; 36: 266-275. http://dx.doi.org/10.1016/S0368-1742(23)80052-2.
http://dx.doi.org/10.1016/S0368-1742(23)...
; DE CARLI, 2001De Carli GA. Colheita e preservação da amostra fecal. In: De Carli GA. Parasitologia clínica: seleção de métodos e técnicas de laboratório para o diagnóstico das parasitoses humanas. São Paulo: Editora Atheneu; 2001. p. 3-26.). The use of flotation techniques enables the separation of fecal debris from parasitic structures, the use of Sheather solution with a density of 1.2 g/ml promotes the flotation of the eggs which present density ranging from 1.023 to 1.050 (DAVID & LINDQUIST, 1982David ED, Lindquist WD. Determination of the specific gravity of certain helminth eggs using sucrose density gradient centrifugation. J Parasitol 1982; 68(5): 916-919. http://dx.doi.org/10.2307/3281005. PMid:6890102.
http://dx.doi.org/10.2307/3281005...
).

The Faust technique showed the lowest sensitivity (73%) and lowest k index = 0.667. This sensitivity finding differs from that found in the study of Souza-Dantas et al. (2007)Souza-Dantas LM, Bastos OPM, Brener B, Salomão M, Guerrero J, Labarthe NV. Técnica de centrífugo-flutuação com sulfato de zinco no diagnóstico de helmintos gastrintestinais de gatos domésticos. Cienc Rural 2007; 37(3): 904-906. http://dx.doi.org/10.1590/S0103-84782007000300051.
http://dx.doi.org/10.1590/S0103-84782007...
, who reported a sensitivity of 100% when compared with the necropsy of the intestinal tract of cats.

In the analysis of the accuracy of the diagnosis of Cystoisospora sp. oocysts, the HPLJ and Sheather techniques showed the same results, both with 66.7% of sensitivity, 97.4% of specificity, PPV of 89.7%, NPV of 89.6% and a k index of 0.700, which were in good agreement with the gold standard (Table 3).

Table 3
Evaluation of the accuracy of the Sheather, Faust and Hoffman-Pons-Janer-Lutz techniques in comparison to the Willis technique (golden standard), for the Cystoisospora sp. diagnosis.

For the diagnosis of Coccidia, flotation techniques using hypertonic solutions are recommended. Our results reinforce those of studies that demonstrate the accuracy achieved by associating the Willis and Sheather techniques, or even the HPLJ and Willis or Sheather techniques in routine laboratory tests (GARCIA et al., 1995Garcia LS, Bullock-Iacullo S, Palmer J, Shimizu RY. Diagnosis of parasitic infections: collection, processing, and examination of specimens. In: Murray PR, Baron EJ, Pfaller MA, Tenover FC, Yolken RH, editors. Manual of clinical microbiology. Washington: ASM Press; 1995. p. 2674-2698.; GARCIA, 2007Garcia LS. Diagnostic medical parasitology. 5th ed. Washington: ASM Press; 2007.).

The accuracy of the results of the detection of T. gondii oocysts showed that the Faust technique presented the highest sensitivity (66.7%), specificity (99.3%), PPV (92.3%), NPV (95.7%) and k index, in agreement with the gold standard (Table 4).

Table 4
Evaluation of the accuracy of the Sheather, Faust and Hoffman-Pons-Janer-Lutz techniques in comparison to the Willis technique (golden standard), for the Toxoplasma gondii diagnosis.

In this analysis, the three techniques showed sensitivities lower than 70%. Flotation in saturated solutions is recommended for oocysts and offers good diagnostic sensitivity (SHEATHER, 1923Sheather AL. The detection of intestinal protozoa and mange parasites by a floatation technique. J Comp Pathol Ther 1923; 36: 266-275. http://dx.doi.org/10.1016/S0368-1742(23)80052-2.
http://dx.doi.org/10.1016/S0368-1742(23)...
; FAUST et al., 1938Faust EC, D’Antoni JS, Odom V, Miller MJ, Peres C, Sawitz W, et al. A critical study of clinical laboratory technics for the diagnosis of protozoan cysts and helminth eggs in feces. Am J Trop Med Hyg 1938; 18(2): 169-183.; DRYDEN et al., 2005Dryden MW, Payne PA, Ridley R, Smith V. Comparison of common fecal flotation techniques for the recovery of parasite eggs and oocysts. Vet Ther 2005; 6(1): 15-28. PMid:15906267.). Therefore, for the diagnosis of T. gondii oocysts, it is advisable to use a combination of the Willis and Faust techniques or the Willis and Sheather techniques, in which the k index was 0.627, representing a good agreement.

In conclusion, this study demonstrated that the combined use of parasitological techniques is important for the diagnosis of intestinal parasites in cats. The association of the Sheather and Willis techniques showed higher accuracy in the diagnosis of Ancylostomatidae and Cystoisospora sp., while the Faust technique in association with the Willis technique (gold standard) showed higher accuracy in the diagnosis of T. gondii.

References

  • Centers for Disease Control and Prevention – CDC. Epi Info [online]. Atlanta: CDC; 2015 [cited 2015 Feb 12]. Available from: http://wwwn.cdc.gov/epiinfo/
    » http://wwwn.cdc.gov/epiinfo/
  • Cerqueira EJL, Arcanjo MS, Alcântara LM. Análise comparativa da sensibilidade da técnica de Willis, no diagnóstico parasitológico da Ancilostomíase. Diálogos de Ciência 2007; 5: 1-7.
  • David ED, Lindquist WD. Determination of the specific gravity of certain helminth eggs using sucrose density gradient centrifugation. J Parasitol 1982; 68(5): 916-919. http://dx.doi.org/10.2307/3281005. PMid:6890102.
    » http://dx.doi.org/10.2307/3281005
  • De Carli GA, Oliveira OLM. Controle de qualidade em parasitologia clínica. In: De Carli GA. Parasitologia clínica: seleção de métodos e técnicas de laboratório para o diagnóstico das parasitoses humanas. São Paulo: Editora Atheneu; 2001. p. 577-610.
  • De Carli GA. Colheita e preservação da amostra fecal. In: De Carli GA. Parasitologia clínica: seleção de métodos e técnicas de laboratório para o diagnóstico das parasitoses humanas. São Paulo: Editora Atheneu; 2001. p. 3-26.
  • Dryden MW, Payne PA, Ridley R, Smith V. Comparison of common fecal flotation techniques for the recovery of parasite eggs and oocysts. Vet Ther 2005; 6(1): 15-28. PMid:15906267.
  • Faust EC, D’Antoni JS, Odom V, Miller MJ, Peres C, Sawitz W, et al. A critical study of clinical laboratory technics for the diagnosis of protozoan cysts and helminth eggs in feces. Am J Trop Med Hyg 1938; 18(2): 169-183.
  • Flanagan PA. - diagnosis, clinical course and epidemiology. A review. GiardiaEpidemiol Infect 1992; 109(1): 1-22. PMid:1499664.
  • Garcia LS, Bullock-Iacullo S, Palmer J, Shimizu RY. Diagnosis of parasitic infections: collection, processing, and examination of specimens. In: Murray PR, Baron EJ, Pfaller MA, Tenover FC, Yolken RH, editors. Manual of clinical microbiology. Washington: ASM Press; 1995. p. 2674-2698.
  • Garcia LS. Diagnostic medical parasitology. 5th ed. Washington: ASM Press; 2007.
  • Hoffman WA, Pons JA, Janer JL. The sedimentation concentration method in schistosomiasis mansoni. PR J Public Health Trop Med 1934; 9: 283-291.
  • Lutz AOO. Schistosoma mansoni e a schistosomatose segundo observações, feitas no Brazil. Mem Inst Oswaldo Cruz 1919; 11(1): 121-155. http://dx.doi.org/10.1590/S0074-02761919000100006.
    » http://dx.doi.org/10.1590/S0074-02761919000100006
  • Machado ER, Santos DS, Costa-Cruz JM. Enteroparasites and commensal among children in four peripheral districts of Uberlândia, State of Minas Gerais. Rev Soc Bras Med Trop 2008; 41(6): 581-585. http://dx.doi.org/10.1590/S0037-86822008000600007. PMid:19142436.
    » http://dx.doi.org/10.1590/S0037-86822008000600007
  • Mariano MLM, Carvalho SMS, Mariano APM, Assunção FR, Carzola IM. Uma nova opção para diagnóstico parasitológico: Método de Mariano e Carvalho. NewsLab 2005; 68: 132-140.
  • McCarthy J, Moore TA. Emerging helminth zoonoses. Int J Parasitol 2000; 30(12-13): 1351-1360. http://dx.doi.org/10.1016/S0020-7519(00)00122-3. PMid:11113260.
    » http://dx.doi.org/10.1016/S0020-7519(00)00122-3
  • Mendes CR, Teixeira ATLS, Pereira RAT, Dias LCS. Estudo comparativo entre os métodos de Kato-Kazt e coprotest. Rev Soc Bras Med Trop 2005; 38(2): 178-180. http://dx.doi.org/10.1590/S0037-86822005000200010. PMid:15821795.
    » http://dx.doi.org/10.1590/S0037-86822005000200010
  • Santos SV, Castro JM. Ocorrência de agentes parasitários com potencial zoonótico de transmissão em fezes de cães domiciliados no município de Guarulhos, SP. Rev Arq Inst Biol 2006; 73(2): 255-257.
  • Schantz PM. Parasitic zoonoses in perspective. Int J Parasitol 1991; 21(2): 161-170. http://dx.doi.org/10.1016/0020-7519(91)90006-S. PMid:1869350.
    » http://dx.doi.org/10.1016/0020-7519(91)90006-S
  • Serra CMB, Uchôa CMA, Coimbra RA. Exame parasitológico de fezes de gatos (Felis catus domesticus) domiciliados e errantes da Região Metropolitana do Rio de Janeiro, Brasil. Rev Soc Bras Med Trop 2003; 36(3): 331-334. http://dx.doi.org/10.1590/S0037-86822003000300003. PMid:12908032.
    » http://dx.doi.org/10.1590/S0037-86822003000300003
  • Sheather AL. The detection of intestinal protozoa and mange parasites by a floatation technique. J Comp Pathol Ther 1923; 36: 266-275. http://dx.doi.org/10.1016/S0368-1742(23)80052-2.
    » http://dx.doi.org/10.1016/S0368-1742(23)80052-2
  • Souza-Dantas LM, Bastos OPM, Brener B, Salomão M, Guerrero J, Labarthe NV. Técnica de centrífugo-flutuação com sulfato de zinco no diagnóstico de helmintos gastrintestinais de gatos domésticos. Cienc Rural 2007; 37(3): 904-906. http://dx.doi.org/10.1590/S0103-84782007000300051.
    » http://dx.doi.org/10.1590/S0103-84782007000300051
  • Tasca T. Incidência de enteroparasitos na cidade mais fria do Brasil: São José dos Ausentes, Rio Grande do Sul. Rev Brasil Anal Clin 2001; 33(1): 10-20.
  • Tosato MEVB, Pilonetto M, Scarin AK. Apuração de custos para a realização de urocultura em um laboratório de médio porte do setor privado. NewsLab 2005; 12(69): 114-142.
  • Vaz AJ. Diagnóstico imunológico das parasitoses. In: De Carli AG. Parasitologia clínica: seleção de métodos e técnicas de laboratório para o diagnóstico das parasitoses humanas. São Paulo: Editora Atheneu; 2001. p. 505-540.
  • Willis HHA. A simple levitation method for the detection of hookworm ova. Med J Aust 1921; 8: 375-376.

Publication Dates

  • Publication in this collection
    10 Nov 2015
  • Date of issue
    Oct-Dec 2015

History

  • Received
    12 Feb 2015
  • Accepted
    27 Apr 2015
Colégio Brasileiro de Parasitologia Veterinária FCAV/UNESP - Departamento de Patologia Veterinária, Via de acesso Prof. Paulo Donato Castellane s/n, Zona Rural, , 14884-900 Jaboticabal - SP, Brasil, Fone: (16) 3209-7100 RAMAL 7934 - Jaboticabal - SP - Brazil
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