臺灣南部洋蔥農作地區空氣中真菌暴露評估與真菌性角膜炎關連性之探討

Fungi Genus and Concentration in the Air of Onion Fields and its Opportunistic Action Related to Mycotic Keratitis in Southern Taiwan

本省落山風地區發現㈨位洋蔥採收工人眼角膜遭真菌感染，其中四名單眼失明。為探討洋蔥採收作業、落山風、空氣中真菌量與眼角膜感染之關連性，本研究以高雄林園（非落山風區）與屏東楓港、車城、恆春（落山風區）洋蔥種植農地為暴露區，以枋寮市集與枋寮蓮霧田為對照組，在洋蔥採收前、採收季節及採收後於選定的採樣點離地約㈧十公分高度，以安德森單階式微生物採樣器（Andersen Single Stage Microbial Sampler）將空氣中真菌捕集於Sabouraud dextrose agar（SDA）與添加40 μg/mL chloramphenicol 的Sabouraud dextrose agar（SDAC）中，25℃下培養4-7㈰後記錄菌落數與菌屬別。採樣時亦記錄當地溫度、相對濕度與風速。SDA與SDAC樣本均顯示，不論在採收前、採收時或採收後，以非落山風地區空氣中真菌濃度最高，落山風地區次之，對照組最低；且在採收季節各地區空氣中真菌濃度均明顯上升。以 T test 檢定325件SDA樣本與353件SDAC樣本顯示其真菌濃度並未達統計上顯著差異（p=0.46）。在洋蔥採收前與採收後各地區均以Cladosporium為主要菌屬，然在採收季節洋蔥田空氣中Aspergillus、Fusarium、Acremonium、Alternaria、Penicillium、Monilia、Mycelia與Rhizopus 濃度顯著上升；Aspergillus更成為落山風地區採收季節的最主要菌屬。濃度顯著上升的菌屬中已知Aspergillus、Fusarium、Acremonium、Alternaria與Penicillium可導致真菌性角膜炎。本省洋蔥作業人員角膜炎感染個案主要集中在落山風地區，該區空氣中真菌濃度雖不若非落山風地區高，然落山風地區特有的強勁風速，助長真菌孢子與洋蔥外皮四散飛揚，作業人員眼角膜被洋蔥外皮或其他外物割傷，高感染性真菌孢子侵入眼睛的機會大增，應是真菌性角膜炎個案集中於落山風地區的主要原因之一。

Nine onion harvesters in Monsoon area of Taiwan were found to suffer from fungal corneal infection. Four lost their eyes. The present study was initiated to explore the relationship among the onion harvesting, Monsoon characteristic, airborne fungi level and mycotic infection. Three onion fields located in the Monsoon area and one in non-Monsoon were selected as the exposed sites, while a fruit garden and a county housing place as the controls. During the periods of onion pre-harvest, harvest and post-harvest seasons, airborne fungi were extracted from approximately 80 cm above the ground of the sampled sites using an Andersen Single Stage Microbial Sampler, and were collected on Sabouraud dextrose agar(SDA) as well as the SDA containing 40 μg/mL chloramphenicol(SDAC). Colonies were counted and fungal genus was identified after incubation at 25℃ for 4-7 days. Temperature, relative humidity and wind velocity were recorded simultaneously with the sampling. Results showed airborne fungal concentration in non-Monsoon onion fields was highest, followed by the Monsoon and the controls independent of the sampling periods. For all of measured sites, the geometric mean of airborne fungal concentration was found highest during the harvest season. The fungal concentrations determined from 325 SDA samples and 353 SDAC samples showed no statistical difference (p=0.46). Cladosporium was the most dominant fungi found during the pre-harvest and post-harvest seasons, while airborne concentrations of Aspergillus, Fusraium, Acremonium, Alternaria, Penicillium, Monilia, Mycelia as well as Rhizopus were significantly increased during the onion harvest. Among them Aspergillus, Fusraium, Acremonium, Alternaria and Penicillium have been identified as keratitis-related genuses. Although fungal concentrations in Monsoon onion fields was lower than those measured in non-Monsoon, the invasion of dangerous fungal pathogens following an eye trauma by airborne sharp exotics (e.g., onion skin) dispersed in high wind may be the reason for corneal ulcer cases occurring in Monsoon area.