Epidemiology and Infection

Original Papers

Molecular typing of Cryptosporidium parvum associated with a diarrhoea outbreak identifies two sources of exposure

J. G. MATTSSONa1, M. INSULANDERa2, M. LEBBADa3, C. BJÖRKMANa4 and B. SVENUNGSSONa2 c1

a1 Department of Parasitology (SWEPAR), National Veterinary Institute and Swedish University of Agricultural Sciences, Uppsala, Sweden

a2 Department of Communicable Disease Control and Prevention, Karolinska University Hospital, Stockholm, Sweden

a3 Department of Parasitology, Mycology, Water and Environmental Microbiology, Swedish Institute for Infectious Disease Control, Stockholm, Sweden

a4 Department of Clinical sciences, Swedish University of Agricultural Sciences Uppsala, Sweden

Abstract

An outbreak of cryptosporidiosis associated with exposure to outdoor swimming-pool water affected an estimated 800–1000 individuals. PCR products were obtained from faecal specimens from 30 individuals who tested positive for Cryptosporidium oocysts. RFLP and sequencing analyses showed that all individuals were infected with Cryptosporidium parvum. Among the infected individuals, five had just swum in an adjacent indoor pool during the same period, and had no identified contact with individuals linked to the outdoor pool. With the use of subgenotyping based on analysis of three mini- and microsatellite loci, MS1, TP14, and GP15, we could identify two sources of exposure. One subtype was associated with the outdoor pool and another with the indoor pool. These data demonstrate that the use of mini- and microsatellite loci as markers for molecular fingerprinting of C. parvum isolates are valuable in the epidemiological investigation of outbreaks.

(Accepted September 07 2007)

(Online publication October 26 2007)

Correspondence:

c1 Author for correspondence: B. Svenungsson, M.D., Ph.D., Associate Professor, Department of Communicable Disease Control and Prevention, Karolinska University Hospital, Norrbacka, S-171 76 Stockholm, Sweden. (Email: bo.svenungsson@sll.se)

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