Earl J. Lewis

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The prevalence of Cryptosporidium, Giardia and Eimeria, in healthy, asymptomatic, post-weaned and mature cattle was investigated on three Maryland farms. One farm, a dairy research facility, had 150 multiparous Holstein milking cows; 24 were examined and Cryptosporidium andersoni was detected in three (12.5%) but neither Giardia nor Eimeria was detected.(More)
Oocysts of Cryptosporidium parvum placed in artificial seawater at salinities of 10, 20, and 30 ppt at 10 degrees C and at 10 ppt at 20 degrees C were infectious after 12 weeks. Those placed in seawater at 20 ppt and 30 ppt at 20 degrees C were infectious for 8 and 4 weeks, respectively. These findings suggested that oocysts could survive in estuarine(More)
Oysters were placed in an aquarium containing artificial seawater, and Cryptosporidium parvum oocysts were added. Oocysts were later found in the gill washings, hemocytes, and gut contents of the oysters. Hemocytes containing oocysts were intubated into four mice. C. parvum stages developed in the ileal epithelia of all of the mice, indicating that the(More)
Fecal droppings of migratory Canada geese, Branta canadensis, collected from nine sites near the Chesapeake Bay (Maryland), were examined for the presence of Cryptosporidium parvum and Giardia spp. Cryptosporidium sp. oocysts were found in feces at seven of nine sites, and Giardia cysts were found at all nine sites. The oocysts from three sites were(More)
Filter-feeding molluscan shellfish can concentrate environmentally derived waterborne pathogens of humans, which can be utilized in the sanitary assessment of water quality. In the present study, oocysts of Cryptosporidium were detected in Bent mussels (Ischadium recurvum) at two Chesapeake Bay sites from which C. parvum-contaminated oysters had previously(More)
The potential cross-reactivity of the combined Cryptosporidium/Giardia direct immunofluorescence antibodies (IFA) of MERIFLUOR and HYDROFLUOR-COMBO tests was examined against tissues containing known developmental stages of 12 pathogens causing the principal infectious diseases in oysters. Spores of Haplosporidium nelsoni and Haplosporidium costale produced(More)
Chromosome association at first meiotic metaphase in tetraploid hybrids between Lolium perenne and L. multiflorum was compared with that in autotetraploid L. perenne. The hybrids were found to have significantly higher levels of bivalent frequency, and lower levels of multivalent and chiasma frequency. A significant increase in multivalent frequency with(More)
Filter-feeding molluscan shellfish can concentrate zoonotic and anthroponotic waterborne pathogens. Cysts of Giardia sp. were detected by immunofluorescent antibodies in tissues of the clams Macoma balthica and M. mitchelli from Rhode River, a Chesapeake Bay (Maryland) subestuary. Molecular tests identified the cysts as Giardia duodenalis Genotype A, the(More)
Oocysts of Cryptosporidium parvum, a zoonotic waterborne pathogen, can be removed by bivalve molluscs from contaminated water and retained on gills and in hemolymph. We identified oocysts of C. parvum in oysters from seven sites in the Chesapeake Bay area. These findings document the presence of C. parvum infectious for humans in oysters intended for human(More)
It was demonstrated by an in vitro slide phagocytosis assay that hemocytes of the Eastern oyster, Crassostrea virginica Gmelin, 1791 are capable of rapid recognition and internalization of infectious Cryptosporidium parvum (AUCP-1 strain) oocysts. The incubation of hemocyte monolayers (8.5 x 10(4) cells) that had received 6.8 x 10(5) or 3.4 x 10(5) oocysts(More)