臺灣博碩士論文加值系統

梨形鞭毛蟲及隱孢子蟲是常見的腸道寄生性原生動物。梨形鞭毛蟲能寄生在人類及多種哺乳動物的小腸而引起梨形鞭毛蟲症；其症狀有腹瀉、胃絞痛、頭暈、噁心等。至於隱孢子蟲則會導致人類及哺乳動物感染隱孢子蟲症，其症狀與梨形鞭毛蟲症類似，這兩種原蟲通常經由飲水進入宿主體內。近幾年美國及英國已爆發多起梨形鞭毛蟲症與隱孢子蟲症的流行；這兩種原蟲之外壁有厚夾膜，因此對水廠的消毒劑具有抗性。目前水廠的消毒方法並不能有效抑制隱孢子蟲卵囊體的生長；同樣的，在偏遠地區，若只用簡單的消毒設備，也不足以去除水中梨形鞭毛蟲的囊體。當務之急乃應建立飲用水水源中致病原生動物存在情形以確保民眾健康。
水體中梨形鞭毛蟲及隱孢子蟲的檢測方法包括三個步驟：水樣的收集與濃縮、原蟲與其他雜質顆粒分離以及原蟲的檢測。ICR原蟲分析法是美國所公告第一個檢測梨形鞭毛蟲與隱孢子蟲的標準方法，但此法的原蟲回收率過低，一直為人所詬病。因此，另一原蟲分析法-Method 1622已在1997年提出。近十年來，國外已爆發多起飲用自來水而引起梨形鞭毛蟲症和隱孢子蟲症的大型感染案例，因此希望藉由檢測本省自來水原水及清水之致病性原生動物及相關水質，了解原蟲之分佈狀況，進而採取必要之行政及技術管制措施，以保障大眾健康。
本研究乃對國內十一處淨水場原水與清水及十三處簡易自來水進行梨形鞭毛蟲、隱孢子蟲及相關水質參數之調查，以了解原蟲在水體中之含量及其與水質參數間之相關性。另外，本研究也對ICR原蟲分析法各個操作步驟的原蟲回收率進行分析，並評估四種市售之飲水機濾心對原蟲的去除效率。
研究結果顯示，國內十一處淨水場之原水中，梨形鞭毛蟲及隱孢子蟲的檢出率分別為79%與69%，平均含量為380.5 cysts/ 100L與184.8 oocysts/ 100L。淨水場的清水中，梨形鞭毛蟲及隱孢子蟲檢出率分別為66%與40%，平均含量為16.4 cysts/ 100L與9.3 oocysts/ 100L。至於十三處簡易自來水設施，梨形鞭毛蟲的檢出率為37%，隱孢子蟲的檢出率為37%。在相關性的比較上，除了梨形鞭毛蟲與隱孢子蟲含量彼此具有相關性外，與濁度及總菌落數亦具相關性。另外梨形鞭毛蟲含量和糞便大腸菌具相關性。十一處淨水廠之整體梨形鞭毛蟲平均感染風險度為0.0296/年，隱孢子蟲之平均感染風險度則為0.0878/年。以聚丙烯濾管進行原水之原蟲回收率分析時，梨形鞭毛蟲與隱孢子蟲的整體回收率都較Polycarbonate濾膜低。四種市售飲水機濾心中，T/C濾心的原蟲截留率最差，而Sediment Filter和聚丙烯管的截留效率最好。目前國內亟需訂定相關議題之指導規範，並對水廠操作提出建議，來防止致病性原生動物的感染，使其感染風險降至最低。

The protozoan parasites Giardia and Cryptosporidium have been recognized as the most common pathogenic protozoa of the gastrointestinal tract. Members of the genus Giardia infect the upper portions of the small intestine in humans and in several other mammals, causing giardiasis with diarrhea, stomach cramps, nausea, and fatigue. Many outbreaks of giardiasis have been reported in the last few decades. Members of the genus Cryptosporidium also cause gastroenteritis in humans and animals and are often responsible for waterborne outbreaks, which are associated with the consumption of surface water or inadequately removing protozoa in water supplies. In the United States and Great Britain, Giardia and Cryptosporidium have been involved in several outbreaks of waterborne gastroenteritis. The thick-walled cysts and oocysts are extremely resistant to commonly used disinfectants such as chlorine. The disinfection method applied currently in the water treatment plant failed to deactivated effectively the growth of Cryptospordium oocyts. Meanwhile, the simple disinfection process used in the retired area is unable to remove completely Giardia cysts. It is important to investigate the outbreak of Giardia and Cryptospordium in the source water to protect the public health.
Methods available for the detection of Giardia and Cryptosporidium in water sample involve three stages: sample collection and concentration; separation of protozoan parasites from other debris; and detection of the parasites. The Information Collection Rule (ICR) protozoan method of USA is the first standard method for detecting Giardia and Cryptosporidium in water samples by a fluorescent antibody procedure. However, this method has been heavily scrutinized for the low recoveries. Method 1622, as improved procedure by adopting the immunomagnetic separation (IMS) is propounded in 1997. Many outbreaks of giardiasis and cryptosporidiosis have been reported in the last decade. Therefore, there is an urgent need to survey the occurrence of protozoan parasites though understanding the relationship between protozoa and water quality parameters in drinking water in order to provide the information for concerning human health.
The research has conducted the sampling and measurement of Giardia and Cryptosporidium in water samples. The sampling sites include 11 major water treatment plants and 13 simple water facilities. The values of water quality parameter from various sampling points were determined for the evaluation of correlation to protozoan parasites. The concentrations of cysts and oocysts in the treated water were applied to the risk analysis equation to calculate the risk of human infection of Giardia and Cryptosporidium in drinking water supplies. The efficiencies of concentration, elution and purification techniques in ICR protozoan method for recovering cysts and oocysts were also evaluated in this research. In addition, we collected four blanks of filter cartridges for water fountain and their removal efficiencies were assayed for Giardia and Cryptosporidium.
It was discovered that the percentage positive of Giardia and Cryptosporidium in the raw water samples from 11 water treatment plants were 79% and 69%, and the average counts were 380.5 cysts/ 100L and 184.8 oocysts/ 100L, respectively. In treated waters, the percentage positive was 66% for Giardia and 40% for Cryptosporidium, while the average counts were 16.4 cysts/ 100L and 9.3 oocysts/ 100L, respectively. In water samples from simple water facilities, the occurrences for both were 37%. Positive correlations were discovered in the following inter-relationships: concentrations of both parasites, parasite concentrations and turbidity level, parasite and heterotrophic bacteria concentrations, and Giardia and fecal coliforms concentrations. The annual risk of infecting parasites from treated water samples in five different plants were 2.96’10-2 for giardiasis and 8.78’10-2 for cryptosporidiosis, respectively. The overall recovery efficiencies of cysts and oocysts were sampled with polypropylene filter higher than these sampled with polycarbonate membrane. When the removal efficiencies by four filter cartridges used in the water fountain were compared, the Sediment filter and polypropylene filter showed the better removal efficiency than the other filters. The results of investigation confirm the need for more stringent regulation. In the mean time, recommendations must be made optimizing treatment process in order to lower the risk of infecting protozoa and the outbreak of waterborne diseases.

目錄
目次.
中文摘要
英文摘要
誌謝
目錄
表目錄
圖目錄
第一章 前言………………………………………………….1
第二章 文獻回顧…………………………………………….5
2.1 梨形鞭毛蟲及隱孢子蟲之感染特性及其對人體
健康危害之風險評估……………………………...……………5
2.2 致病性原生動物在水體中之分佈情形與水質參數之關係…..16
2.3 致病性原生動物分析方法……………………………………..20
2.3.1 採樣方法…………………………………………………….21
2.3.2 分離方法…………………………………………………….24
2.3.3 檢測方法…………………………………………………….27
2.3.4 各種分析方法之比較……………………………………….30
第三章 實驗方法與設備……………………………………………………33
3.1藥品及設備………………………………………………………33
3.1.1藥品…………………………………………. ………………33
3.1.1.1 採樣及前處理…………………...……………………..33
3.1.1.2 水樣濃縮與雜質分離…………………..…………..….34
3.1.1.3 免疫螢光抗體分析法………………………………...34
3.1.1.4 指標微生物檢測…………………..…………………...35
3.1.2 實驗材料與研究設備…………………………………….35
3.1.2.1 採樣及前處理………………………….……………...35
3.1.2.2 水樣濃縮與雜質分離……………………..…………...37
3.1.2.3免疫螢光抗體分析法…………………………...………37
3.1.2.4 其他水質分析……………..…………………………...38
3.2採樣、分析及鏡檢方法………………………………………….38
3.2.1 原蟲採樣方法與步驟………………………………………..38
3.2.1.1傳統濾管過濾法………………………………………….38
3.2.1.2圓盤過濾法……………………………………………….38
3.2.2原蟲濃縮步驟…………………………………………………40
3.2.3原蟲與Percoll-Sucrose梯度澄清分離法…………………….42
3.2.4原蟲之螢光染色與鏡檢步驟…………………………………42
3.3 研究內容….……………………………………………………...46
3.3.1水樣採集與前處理……………………………………………46
3.3.2水樣中梨形鞭毛蟲與隱孢子蟲之檢測………………………46
3.3.3梨形鞭毛蟲囊孢子之培養……………………………………46
3.3.4原蟲之回收率測試……………………………………………47
3.3.5原蟲與其它水質參數之相關性分析…………………………49
3.3.6原蟲之感染風險評估…………………………………………49
3.3.7飲水機過濾裝置對原蟲截留率之評估………………………51
第四章 結果與討論………………………………………………………..…53
4.1 原蟲檢測數據及其含量表示…………………………….……...53
4.2 原蟲在淨水場原水、清水與簡易自來水中的含量及檢出率….60
4.3 原蟲含量與水質參數之相關性分析……………………………70
4.4 傳統過濾法和圓盤過濾法之偵測極限比較……………………78
4.5 不同大腸桿菌群分析方法之檢測結果比較……………………81
4.6 淨水場原蟲去除率與濁度去除率之關係………………………82
4.7 梨形鞭毛蟲症與隱孢子蟲症之感染風險………………………83
4.8 原蟲採樣及分析回收率之評估…………………………………87
4.9 飲水機濾心原蟲截留率之評估…………………………………90
第五章 結論與建議……………………………………...……………………93
參考文獻…………………………………………………………………………...97
表 目 錄
表2.1各國水體梨形鞭毛蟲與隱孢子蟲之散佈情形……………….18
表3.1 水樣之前處理及免疫螢光抗體分析法………………………….45
表4.1 原蟲檢測原始數據及經計算後之原蟲含量…………………….54
表4.2淨水場原水、清水與簡易自來水中之原蟲含量與
水質參數之檢測結果…………………………….……………...61
表4.3原蟲在淨水場原水、清水與簡易自來水中的平均含量
及檢出率…………………………………………………………..70
表4.4自來水原水中之致病性原生動物與水質參數
及指標微生物的相關性…………………………………..……..72
表4.5(a)水廠原水以濾管及濾膜採樣之原蟲偵測極限………………..79
表4.5(b)水廠清水以濾管及濾膜採樣之原蟲偵測極限…………….80
表4.5(c)簡易自來水以濾管及濾膜採樣之原蟲偵測極限……………81
表4.6 國內十一處淨水場對梨形鞭毛蟲、隱孢子蟲
及濁度的物理去除率……………………………………………...83
表4.7 直接飲用自來水廠清水及簡易自來水時梨形鞭毛蟲症
與隱孢子蟲症的感染風險………………………………………86
表4.8 以聚丙烯濾管及Polycarbonate濾膜進行原蟲分析時
各步驟之回收率……………………………………….………88
表4.9以聚丙烯濾管及Polycarbonate濾膜進行原蟲分析時
之總回收率…………….……………………………………89
表4.10飲水機濾心原蟲截留率測試結果………………………………91
圖 目 錄
圖2.1梨形鞭毛蟲的生命週期及說明…………………………………..9
圖2.2隱孢子蟲的生命週期及說明……………………………………10
圖2.3連續式渦流濃縮法的系統裝置圖……………………………….23
圖2.4 Percoll-Sucrose 梯度澄清法……………………………………..24
圖2.5免疫磁性抗體法操作原理示意圖………………………………..26
圖2.6原蟲收集濃縮、分離純化以及檢測步驟中
所使用各項分析技術間之相關性…………………………..32
圖3.1 傳統濾管過濾法之採樣裝置………………………………..…36
圖3.2 圓盤過濾器與Envirochek之採樣裝置 ……………………….37
圖4.1 原水中梨形鞭毛蟲含量與隱孢子蟲含量之相關性……….…..72
圖4.2 原水中隱孢子蟲含量與濁度之相關性…………………………73
圖4.3 原水中隱孢子蟲含量與總菌落數之相關性…………………….74
圖4.4 原水中梨形鞭毛蟲含量與濁度之相關性………………..….…..75
圖4.5 原水中梨形鞭毛蟲含量與總菌落數之相關性……………...…..76
圖4.6 原水中梨形鞭毛蟲含量與糞便大腸菌之相關性………...……..77
圖4.7 不同培養基檢測大腸桿菌群含量之相關性…………………….82

參 考 文 獻
Akin E. W. and Jakubowski W., (1986) "Drinking Water Transmission of Giardiasis in the United States," Wat. Sci. Technol., 18:219-226.
APHA, (1995) Standard Method for the Examination of Water and Wastewater, 15th Edition. APHA, WEF and AWWA, Washington, D.C..
AWWARF, (1991) Giardiasis and Cryptosporidiosis in Water Supplies, Denver, Coloradi\o, USA.
Badenoch J., (1990) Cryptosporidium in Water Supplies, Department of the Environment and Department of Health, London.
Blewett D. A, Wright S. E., Casemore D. P., Booth N. E., and Jones C. E., (1993) "Indective Dose Size Studies on Cryptosporidium Parvum Using Bnotobiotic Lambs," Wat. Sci. Technol., 27:41-64.
Borst R. T., (1992) "Los Angeles Water Carries Parasite Disagree on Potential Danger," Searchlight 2:4.
Boutros S. N., (1989) Sampling and Analysis for Cryptosporidium in PA Public Surface Water Supply Sources, Report to Pennsylvania Division of Water Supply, Harrisburg, PA.
Chung E., Aldom J. E., Chagla A. H., Kostrzynska M., Lee H., Palmateer G., Trevors J. T., Unger S., and De Grandis S., (1998) "Detection of Cryptosporidium parvum oocysts in Municipal Water Samples by the Polymerase Chain Reaction, " J. Microbiol. Meth., 33(2):171-180.
Colbourne J. S., (1989) "Thames Utilities Experience with Cryptosporidium," In Proc. AWWA Wat. Qual. Tech. Conf., Philadelphia, PA, 275-286 Nov.12-16
Current W. L., Reese N. C., Ernst J. V., Bailey W. S., Heyman M. B., and Weinstein W. M., (1983) "Human Cryptosporidiosis in Immunocompetent and Immunodeficient Persons," New England Jour. Med., 308:1252-1257.
Dagan R., Fraser D., Elon J., Kassis I., Deckelbaum R., and Turner S., (1995) "Evaluation of an Enzyme-Immunoassay for the Detection of Cryptosporidium Spp in Stool Specimens from Infants and Young-Children in-Field Studies, " Am. J. Trop. Med. Hyg., 52(2):134-138.
DcRegnier, D. P., Cole, L., Schupp, D. G., and Erlandsen, S. L., (1989) "Viability of Giardia Cysts Suspended in Lade, River and Tap Water," Appl. Environ. Microbiol., 55:1223-1229.
Delcon R., Rose J., Bosch A., Torrella F., and Gerba C., (1993) "Detection of Giardia. Cryptosporidium and Genetic Viruses in Surface and Tap Water Samples in Spain," Int. J. Environ. Hhh. Res, 3:121-129.
Du Pont H. L., Chappell C. L., Sterling C. R., Okhuysen P. C., Rose J. B., Jakubowski W., (1994)"Infectivity of Cryptosporidium parvum for Adult Humans," in Preprint of the Meeting of the Association of American Physicians, Baltimore, Maryland, 29 April - 2 May.
DuPont H. L., Chappell C. L., Sterling C. R., Okhuysen P. C., Rose J. B., and Jakubowski W., (1995) "The Infectivity of Cryptosporidium parvum in Healthy Volunteers, " New England Jour. Med., 332(13): 855-859.
Falk C. C., Karanis P., Schoenen D., and Seitz H. M., (1998) "Bench Scale Experiments for the Evaluation of a Membrane Filtration Method for the Recovery Efficiency of Giardia and Cryptosporidium from water, " Water Res.,32(3):565-568.
Garcia L. S. and Shimizu R. Y., (1997) "Evaluation of Nine Immunoassay Kits (Enzyme Immunoassay and Direct Fluorescence) for Detection of Giardia lamblia and Cryptosporidium parvum in Human Fecal Specimens, " J. Clin. Microbiol., 35(6):1526-1529.
Gornik N., and Exner M., (1991) "Detection Methods and Occurrence of Cryptosporidium sp. in Selected Surface Waters," Zentralbl. Hvg. Umwelnned., 192:124-133.
Haas C. N., Crockett C. S., Rose J. B., Gerba C. P., and Fazil A. M., (1996) "Assessing the Risk Posed by Oocysts in Drinking Water, " J. Am. Water Works Ass, 88(9):131-136.
Haas C. N., Rose J. B., (1994) "Reconcilliation of Microbial Risk Model Risk Models and Outbreak Epidmiology: The Case of the Milwaukee Outbreak," In Proc. Annual Conf. Am. Wat. Assoc., New York, USA, 517-522.
Hend, G. G., (1996) "Chlorine in Water Disinfection," Pure & Appl. Chem., 68:1731-1735.
Hoffman R. M., Standridge J. H., Prieve A. F., Cucunato J. C., and Bernhardt M., (1997) "Using Flow Cytometry to Detect Protozoa, " J. Am. Water Works Ass., 89(9):104-111.
Humphteys S. W., Smith H. V., and Mccreadie A., (1995) "The Occurrence and Viability of Cryptosporidium sp. Oocysts in an Upland Raw Water Source in Central Scotland, " In Protozoan Parasites and Water (Betts WB. et al. eds), Royal Society of Chemistry,. 87-90.
Istre G. R., Dunlop T. S., Gaspard G. B., and Hopkins R. S., (1984) "Waterborne Giardiasis at a Mountain Resort: Evidence for Acquired Immunity," Am. J. Publ. Health., 74:602-604.
Jephcott A. E., Begg T. N., and Backer A. L., (1986) "Outbreak of Giardiasis Associated with Mains Water in United Kingdom," Lancet, 1:370-372.
LeChevallier M. W., Norton W. D., and Lee R. G., (1991) "Occurrence of Giardia and Cyptosporidium in Surface Water Supplies," Appl. Environ. Microbiol., 57:2610-2616.
LeChevallier M. W., Norton W. D., and Lee R. G., "Occurrence of Giardia and Cyptosporidium in Surface Water Supplies," Appl. Environ. Microbiol., 57:2610-2616, 1991.
Lippy E. C., (1978) "Tracing a Giardiasis Outbreak at Berlin, New Hampshire," J. Am. Water Works Ass .,70:512-520.
Lippy E. C., (1981)"Waterborne Disease Occurrence is on the Upswing," J. Am. Water Works Ass .,72:57-62.
Ljungstrom I. And Castor B., (1992) "Immune Response to Giardia Lamblia in a Waterborne Outbreak of Giardiasis in Sweden," J. Med. Microbiol., 36:347-352.
Matheson Z., Hargy T. M., McEwen R. M., Clancy J. R., and Fricker C. R., (1998) "An evaluation of the Gelman Envirochek capsule for the simultaneous concentration of Cryptosporidium and Giardia from water? " Lett. Appl. Microbiol., (in press).
Meyer E. A. andJarroll, E. L. (1980) "Giardisis," Am J. Epidemiol, 111:1-12.
Miller R. A., Brondson M. A., and Morton W. R., (1990) "Environmental Cryptosporidiosis in a Promate Model," J. Infect. Dis., 161:312-315.
Musial C. E., Arrowood M. J., Sterling C. R., and Gerba C. P., (1987) "Detection of Cryptosporidium in Water Using Polypropylene Cartridge Filters," Appl. Environ. Microbiol., 53:687-692.
Nannis P. W., (1993) Testimony to the Subcommittee on Health and the Environment, Commissioner of Health, City of Milwaukee, April 19.
Nash T. E., Herrington D. A., Losonsky G. A., and Levine N. M., (1987) "Experimental Human Infections with Giardia Lamblia," J. Infect. Dis., 156:974-984.
Neringer R., Andersson Y., Baker I. A., (1986) "Waternborne Outbreak of Giardiasis in Sweden. Scand," J. Infect. Dis., 19:85-90.
Nieminski E. C., Schaefer F. W., and Ongerth J.E., (1995) "Comparison of 2 Methods for Detection of Giardia Cysts and Cryptosporidium Oocysts in Water, " Appl. Environ. Microb., 61(5):1714-1719.
Olson ME, Morck AW, Ceri H , (1997) "Preliminary data on the efficacy of a Giardia vaccine in puppies, " Canadian Veterinary Journal-Revue Veterinaire Canadienne., 38: (12) 777-779 .
Olson ME, Morck DW, Ceri H., (1996) "The efficacy of a Giardia lamblia vaccine in kittens. " Canadian Journal of Veterinary Reseach-Revvue Canadienne Derecherche Veterinaire 60: (4) 249-256 .
Petersen C., (1992) "Cryptosporidiosis in Patients Infected with the Human Immunodeficiency Virus," Clinical Infectious Diseases. 15:903-909.
Regli S., Rose J. B., Haas C. N., and Gerba C. P., (1991) "Modeling the Risk from Giardia and viruses in Drinking Water, " J. Am. Water Works Ass ., 83(11):76-84.
Richardson , A. J. et al., (1991) "An Outbreak of Waterborne Cryptosporidiosis in Swindon and Oxfordshire," Epidemiol. Infect., 107:485-495.
Rochelle P. A., DeLeon R., Stewart M. H., and Wolfe R. L., (1997) "Comparison of Primers and Optimization of PCR Conditions for Detection of Cryptosporidium parvum and Giardia lamblia in Water, " Appl. Environ. Microb., 63(1):106-114.
Rodgers M. R., Bernardino C. M., and Jakubowski W., (1993) "A Comparison of Methods for Extracting Amplifiable Giardia DNA from Various Environmental-Samples, " Water Sci. Technol., 27(3):85-88.
Rose J. B., (1990) "Cryptosporidium in Water: Risk of Protozoan Waterborne Transmission, " J. Am. Public Health Assoc.
Rose J. B., Gerba C. P., and Jakubowski W., (1991) "Survey of Potable Water Supplies for Cryptosporidium and Giardia, " Environ. Sci. Technol., 25:1393-1400.
Rose J. B., Haas C.N., and Regli S., (1991) "Risk Assessment and Control of Waterborne Giardiasis, " Am. J. Publ. Health, 81:709-713.
Shepherd K. M. and WynJones A. P., (1996) "An Evaluation of Methods for the Simultaneous Detection of Cryptosporidium Oocysts and Giardia Cysts from Water, " Appl. Environ. Microb., 62(4):1317-1322.
Smith , H. V. , Parker J., Bukhari Z., Campbell D.M., Benton C., Booth N., Mccreadie A., (1993) "Significance of Small Numbers of Cryptosporidium sp. Oocysts in Water," Lancet, 342: 312-313.
Smith H. V. and Rose J. B., (1990) "Waterborne Cryptosporidiosis," Parasitology Today 6:8-12.
Sterling C. R., (1990) "Waterborne Cryptosporidiosis," In Cryptosporidiosis of Man and Animals, (Dubey J. P., Speer C. A., and Fayer R.. Eds.).
The National Cryptosporidium Survey Group, (1993) "A Survey of Cryptosporidium Oocysts in Surface and Groundwaters in the UK, " J. Inst. Wat. Environ. Managmnt., 6:697-793.
Thiriat L., Sidaner F., and Schwartzbrod J., (1998) "Determination of Giardia Cyst Viability in Environmental and Faecal Samples by Immunofluorescence, Fluorogenic Dye Staining and Differential Interference Contrast Microscopy," Lett. Appl. Microbiol., 26(4):237-242.
USEPA, (1994) "National Primary Drinking Water Regulations; Disinfectants and Disinfection Byproducts; Proposed Rule," Federal Reg., 59:145-386.
Vesey G., Hutton P., Champion A., Ashbolt N., Williams K. L., Warton A., and Veal D., (1994a) "Application of Flow Cytometric Methods for the Routine Detection of Cryptosporidium and Giardia in Water, " Cytometry, 16(1):1-6.
Vesey G., Narai J., Ashbolt N., Williams K., and Veal D., (1994b) "Detection of Specific Microorganisms in Environmental-Samples Using Flow-Cytometry, " Method Cell Biol., 42:489-522.
Wallis P. M., Zammuto R. M., and Buchanan-Mappin J. M., (1986) "Cysts of Giardia spp. In Mammals and Surface Waters in Southwestern," Alberta. J. Wildlife Dis., 22:115-118.
Webster K. A., Pow J. D. E., Giles M., Catchpole J., and Woodward M. J., (1993) "Detection of Cryptosporidium-parvum Using a Specific Polymerase Chain-Reaction, " Vet. Parasitol., 50(1):35-44.