臺灣斯文豪氏攀蜥 (Diploderma swinhonis) 皮膚病灶真菌調查

Abstract

新興真菌性疾病日益受到重視，並可能威脅爬蟲類健康；然而，亞洲野生蜥蜴之爬蟲類相關爪甲團囊菌目 (Onygenales) 真菌資料仍相當有限。本研究調查臺灣野生斯文豪氏攀蜥 (Diploderma swinhonis) 皮膚病灶中真菌的出現情形、病裡意義及宿主特徵，並以爬蟲類相關的 Paranannizziopsis 與 Nannizziopsis 為主要研究對象。本研究於大臺北、嘉義及臺南之選定地點進行野外調查，共取得230筆捕獲紀錄，代表229隻不同個體；其中85隻具有肉眼可見皮膚病灶的蜥蜴接受切片採樣及真菌檢測。檢查方法包括真菌培養、形態學觀察、核糖體內轉錄間隔 (internal transcribed spacer, IT) 定序、親緣分析及組織病理學檢查。依綜合診斷結果，將個體分為爬蟲類相關爪甲團囊菌目真菌組、非爪甲團囊菌目／未分類組及真菌陰性組，並評估各組之肉眼與組織病理病灶特徵、人口學資料、形態測量值及體況指數 (body condition index, BCI)。 在85隻接受切片採樣的蜥蜴中，共有19隻成功分離真菌並完成分子鑑定。六隻蜥蜴檢出爬蟲類相關爪甲團囊菌目真菌，占全部捕獲紀錄的 2.61%。其中，大臺北地區五隻蜥蜴分離出 Paranannizziopsis australasiensis；臺南地區一隻蜥蜴之分離株則於 ITS 親緣樹中形成 Nannizziopsis 屬內的獨立分支。僅兩隻 P. australasiensis 陽性蜥蜴於病灶組織內同時發現真菌元素及相關宿主組織反應，占全部捕獲紀錄的0.87%。據我們所知，這是首次於亞洲野外原生爬蟲類中，經組織病理學確認之P. australasiensis 相關皮膚真菌病病例。各分析組的肉眼病灶特徵彼此重疊，無法可靠判斷真菌病因或組織侵犯深度。經分子鑑定的非爪甲團囊菌目分離株均未在組織病理切片中顯示與宿主反應相關的真菌元素；另有六例具有皮膚真菌病的組織病理證據，但其致病真菌仍未能鑑定或分類。六隻爪甲團囊菌目真菌陽性蜥蜴皆為成體，但現有資料不足以評估年齡或性別相關的易感性。三個分析組之 BCI 分布無顯著差異 (Kruskal–Wallis 檢定，H(2) = 3.89，P = 0.143)。 本研究證實爬蟲類相關爪甲團囊菌目真菌存在於臺灣野生斯文豪氏攀蜥，且可造成具有組織侵犯的皮膚真菌病。研究結果亦顯示，僅由病灶中分離出真菌不足以證明其致病性，必須結合分子鑑定與組織病理學結果加以判讀。由於本研究採橫斷式設計，且真菌檢測僅針對具有可見病灶的個體，因此所得檢出頻率受採樣與診斷架構限制，亦未涵蓋亞臨床感染。未來應進行縱向及機率式監測，並整合宿主、環境及多基因座遺傳資料，以進一步釐清此類真菌在臺灣的分布、持續存在、傳播方式及生態意義。

Emerging fungal diseases are increasingly recognized as threats to reptile health, but information on reptile-associated onygenalean fungi in wild Asian lizards remains limited. This study investigated the occurrence, pathological significance, and host associations of fungi recovered from skin lesions of wild Swinhoe’s tree lizard (Diploderma swinhonis) in Taiwan, with particular emphasis on the reptile-associated genera Paranannizziopsis and Nannizziopsis. A cross-sectional field survey was conducted at selected localities in Greater Taipei, Chiayi, and Tainan. A total of 230 capture records representing 229 individual lizards were obtained, and 85 lizards with visible skin lesions underwent biopsy and fungal testing. Samples were evaluated using fungal culture, morphological examination, internal transcribed spacer (ITS) sequencing, phylogenetic analysis, and histopathological examination. Lizards were classified into the onygenalean, non-onygenalean/unclassified, and fungal-negative groups based on combined diagnostic findings. Gross and histopathological lesion characteristics, demographic variables, morphometric measurements, and body condition index (BCI) were evaluated. Fungi were successfully isolated and molecularly identified from 19 of the 85 biopsied lizards. Reptile-associated onygenalean fungi were recovered from six lizards, corresponding to 2.61% of all capture records. Five lizards from Greater Taipei yielded Paranannizziopsis australasiensis, whereas one lizard from Tainan yielded an isolate that formed a distinct lineage within Nannizziopsis in the ITS-based phylogeny. Histopathological evidence of fungal elements accompanied by host tissue responses was demonstrated in only two P. australasiensis-positive lizards, corresponding to 0.87% of all capture records. To the best of our knowledge, these represent the first histopathologically confirmed cases of P. australasiensis-associated dermatomycosis in a free-roaming reptile native to Asia. Gross lesion characteristics overlapped among the analytical groups and did not reliably indicate fungal etiology or histological depth. Molecularly identified non-onygenalean isolates were not histologically associated with host tissue responses, although six additional cases showed evidence of dermatomycosis for which the fungal etiologies remained unidentified or unclassified. All six onygenalean-positive lizards were adults, but the available data were insufficient to evaluate age- or sex-specific susceptibility. BCI distributions did not differ significantly among the three analytical groups (Kruskal–Wallis test, H(2) = 3.89, P = 0.143). These findings demonstrate that reptile-associated onygenalean fungi occur and can cause tissue-invasive dermatomycosis in wild D. swinhonis in Taiwan. They also emphasize that fungal isolation alone does not establish lesion causation and must be interpreted together with molecular and histopathological evidence. Because the survey was cross-sectional and testing was directed toward animals with visible lesions, the reported frequencies are conditional on the sampling and diagnostic framework and do not account for subclinical infection. Longitudinal and probability-based surveillance integrating host, environmental, and multilocus genetic data will be required to clarify fungal distribution, persistence, transmission, and ecological significance in Taiwan.