Susceptibility of five strains of Cryptosporidium parvum oocysts to UV light

A long-term epidemiological study of Cryptosporidium molnari in aquacultured European sea bass (ESB) and gilthead sea bream (GSB) was performed in different types of facilities on the Atlantic, Cantabric, and Mediterranean coasts. Four types of studies were carried out. In study A, fish raised from juveniles to marketable size (ongrowing stage) were periodically sampled in three different types of cultures. Studies B and C focused on hatchery and nursery facilities. In study D, occasional samplings were performed during mortality or morbidity outbreaks. As a general trend, C. molnari was more prevalent in GSB than in ESB. Data on the distribution pattern of C. molnari in total sampled GSB (studies A, B, and D) had a variance higher than the mean (overdispersion). In GSB (study A), the type of ongrowing system (sea cages, earth ponds, or indoor tanks) was found to have no significant effect. There was a significant relationship between the presence of the parasite and both fish weight and season. The highest infection values were recorded in spring. Prevalence and intensity had convex weight profiles, with a peak in 30-to 100-g fish. In study D, the prevalence of infection was higher in fish recently introduced in sea cages and in preongrowing systems. In studies B and C, fish were almost never infected before entering the postlarval and nursery facilities. The parasite seems to enter the host mainly through the water in production steps with less stringent water treatment. Recirculation systems and fish cannibalism could contribute to oocyst concentration and dispersion in aquaculture facilities.Parasite populations tend to show an aggregated distribution in host populations, in which different factors, such as host size, host density, and environment, are involved (4, 35). Hostparasite relationships at the population level are complex, and many factors related to the microhabitat (the host) and the macrohabitat (the host environment) have to be considered. In farmed hosts, culture conditions clearly affect this relationship, as they influence host density and other collateral factors. Gilthead sea bream (Sparus aurata L.) and European sea bass (Dicentrarchus labrax L.) are successfully cultured in the Mediterranean Sea and the Atlantic Ocean. Their production has reached almost 100,000 tons in the Mediterranean basin (17). With the increase of intensive farming, severe disease outbreaks have been reported, including those produced by emergent parasites (9).A new protozoan parasite, Cryptosporidium molnari (Apicomplexa) was described from cultured sea bass and sea bream (3), and homologous transmission and cross-transmission have recently been demonstrated under experimental conditions (40). Cryptosporidia are small coccidian parasites recognized as significant pathogens for humans and many other vertebrates (12,13,18,19,46). The importance of piscine species remains to be determined, but C. molnari may produce pathological effects, mainly in small fish (3). Epidemiological data are very important for ascertaini...

Section: Discussionmentioning

confidence: 99%

Epidemiology ofCryptosporidium molnariin Spanish Gilthead Sea Bream (Sparus aurataL.) and European Sea Bass (Dicentrarchus labraxL.) Cultures: from Hatchery to Market Size

Sitjà‐Bobadilla

Padrós

Aguilera

et al. 2005

“…Consequently, alternative disinfectants, such as UV light, have been investigated. Numerous studies have demonstrated the efficacy of UV light for disinfecting oocysts of at least six C. parvum isolates (2,3,11,14,16,24). However, all of the UV disinfection studies conducted to date have used C. parvum type 2 oocysts.…”

mentioning

confidence: 99%

UV Inactivation of Cryptosporidium hominis as Measured in Cell Culture

Johnson¹,

Linden

Ciociola

et al. 2005

The Cryptosporidium spp. UV disinfection studies conducted to date have used Cryptosporidium parvum oocysts. However, Cryptosporidium hominis predominates in human cryptosporidiosis infections, so there is a critical need to assess the efficacy of UV disinfection of C. hominis. This study utilized cell culture-based methods to demonstrate that C. hominis oocysts displayed similar levels of infectivity and had the same sensitivity to UV light as C. parvum. Therefore, the water industry can be confident about extrapolating C. parvum UV disinfection data to C. hominis oocysts.

“…It has been reported previously that different isolates of Escherichia coli have different levels of UV sensitivity (30). In contrast, multiple isolates of C. parvum were found to be equally sensitive to UV disinfection (8,27). This research provides the first evidence that different isolates of G. lamblia may not necessarily be equally sensitive to UV disinfection.…”

Section: Discussionmentioning

confidence: 48%

“…Clancy et al (8) concluded that five isolates of Cryptosporidium parvum oocysts were equally sensitive to UV light. In contrast, no direct comparisons between the UV inactivation properties of different Giardia spp.…”

mentioning

confidence: 99%

Comparison of Levels of Inactivation of Two Isolates of Giardia lamblia Cysts by UV Light

Liu

Craik

Smith

et al. 2007

The effects of 254-nm UV irradiation on two human isolates (WB and H3) of Giardia lamblia cysts were assessed using a collimated beam protocol and a Mongolian gerbil model. The levels of infection of cysts in the gerbils were assessed based on the presence of cysts in feces and the presence and activity of trophozoites in the small intestine of inoculated gerbils. The results suggest that there were differences in the infectivities of the WB and H3 isolates, as well as in susceptibilities of the parasites to UV light. Without UV exposure, gerbils were more readily infected by isolate H3 cysts. After UV exposure of the cysts, however, the gerbils were more susceptible to isolate WB cysts.