Lu Ta-Li, Wong Jun-Yue, Tan Ta-Lun, Hung Yong-Wei
Taiwan Academy of Veterinary Internal Medicine, Taipei, Taiwan.
Cardiospecial Veterinary Hospital, No.34, Sec. 2, Heping E. Rd, Taipei, 106, Taiwan.
Parasit Vectors. 2017 Nov 9;10(Suppl 2):484. doi: 10.1186/s13071-017-2435-7.
Heartworm, Dirofilaria immitis, has long been recognized in Taiwanese dogs but feline heartworm infection has been largely overlooked by veterinarians and pet owners. The main goal of this study was to determine the prevalence and epidemiology of canine and feline heartworm infection in Taiwan.
Household dogs and cats were selected from 103 veterinary hospitals in 13 cities throughout Taiwan. All animals were at least 1 year old, had received no heartworm prevention for more than 1 year, and had lived in the same city for at least 1 year. Client consent was obtained and an owner questionnaire was completed for each patient. Blood samples were collected from each canine patient and tested at each veterinary hospital for microfilariae and for circulating antigen. A positive result on either test was considered to confirm mature heartworm infection. Blood was collected from each feline patient and examined for microfilariae and a feline heartworm antigen/antibody test was performed. Descriptive statistics were used for heartworm prevalence. Multivariate logistic regression analysis was used to determine the relationships between heartworm infection and multiple risk factors.
A total of 2064 household dogs and 616 household cats from 103 veterinary hospitals throughout Taiwan were included in the study. The overall prevalence of canine heartworm disease was 22.8% (471/2064). In heartworm-positive dogs, 63% were both microfilaria positive and antigen positive, 35% were microfilaria negative and antigen positive, and only 2% were microfilaria positive and antigen negative. In the comparison of different life style groups, outdoor dogs (N = 797) had significantly higher heartworm prevalence rate than indoor dogs (N = 1267; p = 0.000). The heartworm prevalence rate in dogs presented with dyspnea and cough was as high as 51%. The overall prevalence of antibody-positive cats was 6.7% (41/616) and the antigen-positive prevalence rate was 3.1% (19/616). In 41 antibody-positive cats, 6 of them were also antigen-positive. In 19 antigen-positive cats, 13 of them were antibody negative. In antibody-positive and antigen-negative cats, half had no clinical signs. In antigen-positive cats, 21% had no clinical signs and only 38% had classic heartworm clinical signs (dyspnea, cough, or gastrointestinal signs).
Our canine study showed that southern and eastern Taiwan have the highest heartworm prevalence. Dogs not receiving preventive and living outdoors or those that have either cough or dyspnea have a high incidence of heartworm infection. We also confirmed that feline heartworm exposure exists in most cities in Taiwan. The diagnosis of feline heartworm infection will remain challenging for clinicians, however, without a consistent relationship between the presence of heartworm infection and clinical signs and the vagaries of microfilaria and antigen/antibody testing.
犬心丝虫，即恶丝虫，在台湾犬类中早有发现，但兽医和宠物主人大多忽视了猫的心丝虫感染情况。本研究的主要目的是确定台湾犬猫心丝虫感染的患病率及流行病学特征。
从台湾13个城市的103家兽医医院选取家养犬猫。所有动物至少1岁，超过1年未接受心丝虫预防措施，且在同一城市生活至少1年。获得了客户同意，并为每位患者填写了一份主人问卷。从每只犬类患者采集血样，并在每家兽医医院检测微丝蚴和循环抗原。任何一项检测结果呈阳性都被视为确诊为成熟的心丝虫感染。从每只猫科患者采集血液，检测微丝蚴，并进行猫心丝虫抗原/抗体检测。采用描述性统计分析心丝虫患病率。采用多因素逻辑回归分析确定心丝虫感染与多种风险因素之间的关系。
本研究纳入了台湾103家兽医医院的2064只家养犬和616只家养猫。犬心丝虫病的总体患病率为22.8%（471/2064）。在心丝虫阳性犬中，63%微丝蚴阳性且抗原阳性，35%微丝蚴阴性且抗原阳性，仅2%微丝蚴阳性且抗原阴性。在不同生活方式组的比较中，户外犬（N = 797）的心丝虫患病率显著高于室内犬（N = 1267；p = 0.000）。出现呼吸困难和咳嗽的犬的心丝虫患病率高达51%。抗体阳性猫的总体患病率为6.7%（41/616），抗原阳性患病率为3.1%（19/616）。在41只抗体阳性猫中，6只也为抗原阳性。在19只抗原阳性猫中，13只为抗体阴性。在抗体阳性且抗原阴性的猫中，一半没有临床症状。在抗原阳性猫中，21%没有临床症状，只有38%有典型的心丝虫临床症状（呼吸困难、咳嗽或胃肠道症状）。
我们对犬类的研究表明，台湾南部和东部的心丝虫患病率最高。未接受预防措施且生活在户外的犬或有咳嗽或呼吸困难症状的犬心丝虫感染发生率较高。我们还证实台湾大多数城市存在猫心丝虫感染情况。然而，对于临床医生来说，猫心丝虫感染的诊断仍具有挑战性，因为心丝虫感染的存在与临床症状之间没有一致的关系，而且微丝蚴和抗原/抗体检测存在不确定性。
