Surface Waters and Urban Brown Rats as Potential Sources of Human-Infective Cryptosporidium and Giardia in Vienna, Austria.

Silvia Cervero-Aragó,Regina Sommer,Iveta Häfeli,Julia Walochnik,Gerhard Lindner,Amélie Desvars-Larrive

doi:10.3390/microorganisms9081596

Abstract

Cryptosporidium and Giardia are waterborne protozoa that cause intestinal infections in a wide range of warm-blooded animals. Human infections vary from asymptomatic to life-threatening in immunocompromised people, and can cause growth retardation in children. The aim of our study was to assess the prevalence and diversity of Cryptosporidium and Giardia in urban surface water and in brown rats trapped in the center of Vienna, Austria, using molecular methods, and to subsequently identify their source and potential transmission pathways. Out of 15 water samples taken from a side arm of the River Danube, Cryptosporidium and Giardia (oo)cysts were detected in 60% and 73% of them, with concentrations ranging between 0.3–4 oocysts/L and 0.6–96 cysts/L, respectively. Cryptosporidium and Giardia were identified in 13 and 16 out of 50 rats, respectively. Eimeria, a parasite of high veterinary importance, was also identified in seven rats. Parasite co-ocurrence was detected in nine rats. Rat-associated genotypes did not match those found in water, but matched Giardia previously isolated from patients with diarrhea in Austria, bringing up a potential role of rats as sources or reservoirs of zoonotic pathogenic Giardia. Following a One Health approach, molecular typing across potential animal and environmental reservoirs and human cases gives an insight into environmental transmission pathways and therefore helps design efficient surveillance strategies and relevant outbreak responses.

Highlights

Even though the Danube River is the second largest river in Europe, information regarding the prevalence of protozoan enteric pathogens in its water is scarce
Using a One Health approach, this study aimed to (i) assess for the first time the prevalence of parasitic protozoa such as Cryptosporidium and Giardia in urban surface water such as the Danube Canal, a side-arm of the River Danube that flows through the city center of Vienna, Austria, and in urban brown rats trapped in the city center of Vienna, (ii) determine the diversity and zoonotic potential of the aforementioned parasites by identifying species, genotypes, and assemblages, and (iii) assess the potential role of the
The present study reports for the first time the prevalence of Cryptosporidium, Eimeria, and Giardia at the wildlife–water interface ecosystem in two densely populated sites located in the city center of Vienna, the capital of Austria

Summary

Introduction

Even though the Danube River is the second largest river in Europe, information regarding the prevalence of protozoan enteric pathogens in its water is scarce. Kirschner et al [1] reported that human-associated faecal pollution is a crucial problem throughout the Danube River basin, posing a threat to all types of water uses. Cryptosporidium and Giardia are parasitic protozoa responsible for diarrheal diseases in humans and other animals worldwide [2]. In the USA these parasites are responsible for 30,000 cases of diarrhea every year [3]. The two parasites have similar life cycles, characterized by an environment-resistant infective stage, the Cryptosporidium oocysts and Giardia cysts, which initiate infection Infections caused by the two parasites are underreported, the prevalence of Cryptosporidium among the world’s population is estimated to range between 3–5% while prevalence is approximately 10% for Giardia [3].

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Methods

Conclusion