Evaluation of a PCR test for the detection ofHaemophilus paragallinarumin China

Abstract

The application of a recently described PCR test for the detection of Haemophilus paragallinarum in China is described. The test was used to examine a total of 127 chickens sourced from a challenge trial (38 chickens), a respiratory disease-free experimental chicken farm (50 chickens) and eight farms with suspect infectious coryza (IC) outbreaks (39 chickens). The PCR results were compared with traditional culture. The PCR detected 14/14 infected birds in the challenge trial as compared with 13/14 for culture. The 50 chickens from the disease-free experimental farm were all negative by both PCR and culture. PCR yielded 15/39 birds and 6/8 commercial farms positive as compared with 8/39 birds and 4/8 farms positive by culture. All farms positive by PCR had chickens showing the typical clinical signs of IC, indicating that culture failed to confirm coryza on two farms that had the typical clinical signs of the disease. Although chickens on two commercial farms were thought initially to be suffering from coryza, detailed clinical examination yielded no birds with typical clinical signs. The 12 chickens examined from these two farms were negative by both PCR and culture. The results suggest that the PCR test for H. paragallinarum is a suitable alternative to culture even under the typical field and laboratory conditions that operate in China.

Isolation and molecular identification of Avibacterium paragallinarum in suspected cases of infectious coryza

“…paragallinarum and the subsequent requirement for special media has made the isolation and identification of this organism a costly and laborious task (3,11). Furthermore, Av.…”

“…The swabs were soaked in 400 µL of phosphate-buffered saline for 1 h at room temperature and processed using a modification of the method described previously (7,11). In brief, the samples were centrifuged at 2000 rpm for 5 min to settle the blood.…”

Identificação de Avibacterium paragallinarum em frangos de corte e poedeiras comerciais no Estado de Pernambuco

“…Narita et al (1978) registraram o isolamento e identificação de A. paragalinarum no Brasil. Em laboratórios de países em desenvolvimento que geralmente têm um menor nível de recursos e muitos problemas de contaminação, o diagnóstico de CI pela cultura e a caracterização com testes bioquímicos é complicado (Chen et al 1998).…”

“…Clinicamente, as galinhas com sinais sugestivos de CI, também podem estar acometidas por outras doenças, como por exemplo, Ornithobacterium rhinotracheale, cólera aviária crônica, bouba aviária, síndrome da cabeça inchada e avitaminose (Amonsin et al 1997, Blackall & Matsumoto 2003. Chen et al (1998) recomendaram que os swabs para isolamento de A. paragalinarum sejam transportados em G-PBS ou, simplesmente, armazenados secos e enviados para o laboratório a 4°C, com o período de uma semana entre o tempo de coleta e o processamento da amostra, não influenciando negativamente nos resultados do teste de PCR, porém negativando em testes de cultura. A superioridade do teste de PCR em relação a cultura tradicional é evidente pelo fato de que para o sucesso na cultura, deve ser armazenado em local seco ou no G-PBS e esfregaços devem ser examinados dentro de no máximo três dias.…”

“…A PCR para diagnóstico de A. paragallinarum deve ser utilizada como um teste realizado no grupo ou plantel para que se tenha um custo reduzido (Chen et al 1998).…”