Research Centre of Infection and Immunology, The University of Hong Kong, Pokfulam, China.
J Clin Microbiol. 2012 Nov;50(11):3534-41. doi: 10.1128/JCM.01590-12. Epub 2012 Aug 22.
Dirofilariasis is globally the commonest manifestation of zoonotic filariasis. We report the detection of a novel canine species causing human and canine dirofilariasis in Hong Kong. Three human cases occurring over 10 months were identified, one presenting with cervical lymphadenopathy, one with an abdominal subcutaneous mass, and one with a subconjunctival nodule. Transected worms recovered from the resected abdominal subcutaneous mass were morphologically compatible with Dirofilaria. The cox1 gene sequences of the three human isolates were identical; however, they were only 96.2% and 89.3% identical to the cox1 gene of Dirofilaria repens and Dirofilaria immitis, respectively. Sequencing of the 18S-ITS1-5.8S gene cluster was successful in the intact worm, and the nucleotide sequences were 94.0% and 94.9% identical to those of D. repens and D. immitis, respectively. Screening of the blood samples from 200 dogs and 100 cats showed the presence of the novel Dirofilaria species in 3% (6/200) of the dogs' but none of the cats' blood samples. Nucleotide sequences of the cox1 gene and 18S-ITS1-5.8S gene clusters of the dogs' samples were identical to those in the human samples. The sera of canines infected by this novel Dirofilaria species were negative when tested with the SNAP 4Dx D. immitis detection kit, except in the case of dogs with a mixed infection with D. immitis as detected by PCR. The results from this study suggest that this novel Dirofilaria species is a cause of filarial infection in humans and dogs in Hong Kong. We propose to name this Dirofilaria species "Candidatus Dirofilaria hongkongensis."
犬恶丝虫病是全球最常见的动物源性丝虫病。我们报告在香港发现了一种新型犬种，可引起人类和犬类的恶丝虫病。在过去 10 个月中发现了 3 例人类病例，其中 1 例表现为颈部淋巴结病，1 例表现为腹部皮下肿块，1 例表现为结膜下结节。从切除的腹部皮下肿块中取出的被切断的蠕虫在形态上与恶丝虫相符。从 3 例人类分离株中获得的 cox1 基因序列完全相同；然而，它们与犬恶丝虫和犬心丝虫的 cox1 基因的相似度分别为 96.2%和 89.3%。成功地对完整蠕虫进行了 18S-ITS1-5.8S 基因簇测序，其核苷酸序列与犬恶丝虫和犬心丝虫的相似度分别为 94.0%和 94.9%。对 200 只犬和 100 只猫的血液样本进行筛查显示，在 3%（6/200）的犬血样中存在新型犬恶丝虫，但在猫血样中均未发现。犬血样 cox1 基因和 18S-ITS1-5.8S 基因簇的核苷酸序列与人类样本完全相同。用 SNAP 4Dx 犬心丝虫检测试剂盒检测感染这种新型犬恶丝虫的犬血清均为阴性，除了通过 PCR 检测到犬混合感染犬心丝虫的情况外。本研究结果表明，这种新型犬恶丝虫是导致香港人类和犬类丝虫感染的原因。我们建议将这种新型犬恶丝虫命名为“香港犬恶丝虫候选种”。
