Phylogenetic Analysis Implicates Birds as a Source of Cryptosporidium spp. Oocysts in Agricultural Watersheds

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• 作者：Kristen L. Jellison ; Daniel L. Distel ; Harold F. Hemond ; David B. Schauer
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：May 15, 2007
• 年：2007
• 卷：41
• 期：10
• 页码：3620 - 3625
• 全文大小：134K
• 年卷期：v.41,no.10(May 15, 2007)
• ISSN：1520-5851

文摘

Cryptosporidium parvum and C. hominis are protozoanparasites responsible for cryptosporidiosis, an acutegastrointestinal illness that can be life-threatening forimmunocompromised persons. Sources and genotypes ofCryptosporidium oocysts were investigated in two agriculturalareas within the Wachusett Reservoir watershed, adrinking water source for Boston, Massachusetts. Twobrooks (denoted Brook SF and Brook JF, respectively), eachdowngradient from a dairy farm, were chosen as samplesites. For one year, Brooks SF and JF were sampled monthly;oocysts were detected in 6 (50%) out of 12 samplesfrom Brook JF, and no oocysts were detected in BrookSF. Oocyst genotypes from agricultural surface waters werecompared to oocyst genotypes from Genbank, as well asfecal samples of cattle and birds, using phylogenetic analysisof a hypervariable region of the 18S rRNA gene by bothneighbor-joining and parsimony methods. Results showextensive heterogeneity among Cryptosporidium spp. 18SrRNA sequences, and also suggest that birds are an oocystsource in this watershed. Principal components analysisshowed oocyst presence correlating strongly with seasonalfactors, and oocysts in surface waters were only detectedin the summer through late fall, co-incident with thepresence of migratory birds in this watershed. If birds areconfirmed to be an important source of oocysts infectiousto humans, the data suggest that protection of raw drinkingwater supplies in some agricultural areas may dependupon management and control of resident and migratorybird populations.