Volume 20, Number 4—April 2014
Large Outbreak of Cryptosporidium hominis Infection Transmitted through the Public Water Supply, Sweden
|Sample type||No. samples||No. positive samples||Analyzed volume, L||Presumptive no. oocysts, min–max/10 L||Confirmed no. oocysts, min–max/10 L||Time span for positive samples|
|Raw water†||18||10||100||0.2–3.1||0.1–0.7||2010 Nov 27–2011 Feb 9|
|Drinking water, WTP-Ö†||7||7||800–1,500||0.047–1.4||0.02–1.3||2010 Nov 27–2011 Jan 20|
|Drinking water, distribution network||9||9||800–1,400||0.063–0.36||0.05–0.05||2010 Nov 29–2011 Jan 31|
|Wastewater, untreated†||21||13||0.05‡||200–270,000||§–160,000||2010 Nov 29–2011 Feb 17|
|Wastewater, treated||15||14||0.25–0.3‡||30–21,000||30–10,000||2010 Dec 1–2011 Jan 24|
|Recipient (Lake Storsjön)||14||8||9–10||2–21||1–18||2010 Nov 29–2011 Mar 22|
|Connected streams||8||5||2–10||1,300–5,000||950–3,500||2010 Nov 30–Dec 14|
|Other¶||10||2||10–17||1–3||1–3||2010 Nov 30–2011 Jan 17|
|Total||102||68||0.047–270,000||0.02–160,000||2010 Nov 27–2011 Mar 22|
*Min, minimum; max, maximum; WTP-Ö, water treatment plant–Östersund.
†Details are available in Technical Appendix Figures 1 and 2.
‡These samples consisted of 30-mL aliquots from every 50–60 m3 of wastewater produced over 24 h.
§Not possible to determine the lowest density by microscopy because of substantial background material in the concentrated water sample.
¶Samples from sources, such as swimming pools, water used to flush the distribution network, and sediment from fire hydrants.