Comparison of three cryptosporidiosis outbreaks in Western Australia: 2003, 2007 and 2011.

Cryptosporidium is a protozoan parasite that causes the diarrhoeal disease, cryptosporidiosis. Although many species have been identified, the majority of human disease worldwide is caused by two species; Cryptosporidium parvum and Cryptosporidium hominis. In Australia, data from the National Notifiable Diseases Surveillance System (NNDSS) show that cryptosporidiosis outbreaks occur every few years. To better understand the transmission, trends and nature of cryptosporidiosis outbreaks in Western Australia, epidemiological and genomic data from three cryptosporidiosis outbreaks in 2003, 2007 and 2011 were reviewed. The 2007 outbreak was the largest (n = 607) compared with the outbreaks in 2003 (n = 404) and 2011 (n = 355). All three outbreaks appeared to have occurred predominantly in the urban metropolitan area (Perth), which reported the highest number of case notifications; increases in case notifications were also observed in rural and remote areas. Children aged 0-4 years and non-Aboriginal people comprised the majority of notifications in all outbreaks. However, in the 2003 and 2007 outbreaks, a higher proportion of cases from Aboriginal people was observed in the remote areas. Molecular data were only available for the 2007 (n = 126) and 2011 (n = 42) outbreaks, with C. hominis the main species identified in both outbreaks. Subtyping at the glycoprotein 60 (gp60) locus identified subtype IbA10G2 in 46.3% and 89.5% of C. hominis isolates typed, respectively, in the 2007 and 2011 outbreaks, with the IdA15G1 subtype was identified in 33.3% of C. hominis isolates typed in the 2007 outbreak. The clustering of cases with the IdA15G1 subtype in the remote areas suggests the occurrence of a concurrent outbreak in remote areas during the 2007 outbreak, which primarily affected Aboriginal people. Both the C. hominis IbA10G2 and IdA15G1 subtypes have been implicated in cryptosporidiosis outbreaks worldwide; its occurrence indicates that the mode of transmission in both the 2007 and 2011 outbreaks was anthroponotic. To better understand the epidemiology, sources and transmission of cryptosporidiosis in Australia, genotyping data should routinely be incorporated into national surveillance programmes.

Investigation of a swimming pool-associated cryptosporidiosis outbreak in the Kimberley region of Western Australia.

Cryptosporidiosis is a gastroenteric disease caused by the protozoan parasite Cryptosporidium, which manifests primarily as watery diarrhoea. Transmitted via the faecal-oral route, infection with the parasite can occur through ingestion of water, food or other fomites contaminated with its infective oocyst stage. In the months of November and December 2012, there were 18 notified cases of cryptosporidiosis from Broome, Western Australia. The 5-year average for the Kimberley region for this period is <1 case. Interviews conducted by Broome local government staff on the notified cases revealed that 11/18 cases had been swimming at the Broome public swimming pool. Molecular analyses of extracted DNA performed on 8/18 microscopy-positive faecal samples from interviewed cases and three water samples from different locations at the hypervariable glycoprotein 60 (gp60) gene, identified the C. hominis IbA10G2 subtype in all human samples and one water sample.

Identification of novel and zoonotic Cryptosporidium species in fish from Papua New Guinea.

There is still limited information on the distribution of Cryptosporidium species and genotypes in fish. The present study investigated the prevalence of Cryptosporidium species in cultured freshwater (n=132), wild freshwater (n=206) and wild marine (n=276) fish in Papua New Guinea (PNG) by PCR screening at the 18S rRNA locus. A total of seven fish (2 cultured freshwater, 1 wild freshwater and 4 wild marine fish) were identified as positive for Cryptosporidium. Specifically, Cryptosporidium was found in four different host species (Nile tilapia, Oreochromis niloticus; silver barb, Puntius gonionotus; mackerel scad, Decapterus maracellus and oblong silver biddy, Gerres oblongus), giving an overall prevalence of 1.14% (95% CI: 0.3-2%, n=7/614). Of the seven positive isolates, five were identified as C. parvum and two were a novel piscine genotype, which we have named piscine genotype 8. Piscine genotype 8 was identified in two marine oblong silver biddies and exhibited 4.3% genetic distance from piscine genotype 3 at the 18S locus. Further subtyping of C. parvum isolates at the 60 kDa glycoprotein (gp60) locus identified 3 C. parvum subtypes (IIaA14G2R1, IIaA15G2R1 and IIaA19G4R1) all of which are zoonotic and a C. hominis subtype (IdA15G1). The zoonotic Cryptosporidium were identified in fish samples from all three groups; cultured and wild freshwater and wild marine fish. Detection of Cryptosporidium among aquaculture fingerlings warrants further research to gain a better understanding of the epidemiology of Cryptosporidium infection in cultured fish. The identification of zoonotic Cryptosporidium genotypes in fish from PNG has important public health implications and should be investigated further.