Fecal Shedding Patterns Research Articles

DIFFERENT FECAL SHEDDING PATTERNS OF TWO COMMON STRAINS OF HEPATITIS E VIRUS AT THREE JAPANESE SWINE FARMS

Zoonotic infections caused by eating the meat of deer, wild boar, and pig have been suggested in Japan, a country that is not epidemic for hepatitis E caused by hepatitis E virus (HEV). This virus is widely spread in domestic pigs in both epidemic and non-epidemic countries. We studied fecal HEV shedding patterns on three Japanese farms that had two common genotype III HEV strains. Two of the three farms had high shedding peaks (75% and 100%) in pigs 1-3 months of age, suggesting that these animals had the highest risk of spreading HEV through feces. Another farm had a low shedding rate in animals six months of age and a low prevalence of the IgG antibody to HEV. Fecal IgA antibody to HEV was found in sucking pigs < 13 days of age on farms that had high and low shedding patterns. A small fraction of pigs (3 of 43 [7%]) at the finishing stage (5-6 months of age) still shed HEV on the three farms.

Intermittent long-term shedding and induction of carrier birds after infection of chickens early posthatch with a low or high dose of Salmonella enteritidis

Poultry are very likely to become infected with Salmonella in the early posthatch period, due to environmental contamination. The purpose of this study was to evaluate the effect of infection dose on the risk of persistent infection in laying hens. In this study, young layer chicks were orally infected with a low (10(2) at 1 d posthatch) or a high dose (10(9) cfu at 1 wk posthatch) of Salmonella Enteritidis. The pattern and duration of fecal shedding was studied for 18 wk. All chickens shed Salmonella early after infection and shed Salmonella intermittently during the whole study period. There were more positive birds in the high-dose group than in the low-dose group in the first weeks following Salmonella exposure. From 10 wk postinfection onwards, however, birds that were orally infected with the low dose of Salmonella Enteritidis shed more Salmonella than the birds that received the high dose. At 18 wk of age, there was no difference in cecal colonization between the treatment groups. It can be concluded that infection of newly hatched chicks with a low dose of Salmonella Enteritidis can lead to persistent infection until onset of lay, hereby excreting Salmonella bacteria intermittently.

Seasonal Shedding of MultipleCryptosporidiumGenotypes in California Ground Squirrels (Spermophilus beecheyi)

Twelve percent of 853 California ground squirrels (Spermophilus beecheyi) from six different geographic locations in Kern County, Calif., were found to be shedding on average 44,482 oocysts g of feces(-1). The mean annual environmental loading rate of Cryptosporidium oocysts was 57,882 oocysts squirrel(-1) day(-1), with seasonal patterns of fecal shedding ranging from <10,000 oocysts squirrel(-1) day(-1) in fall, winter, and spring to levels of 2 x 10(5) oocysts squirrel(-1) day(-1) in summer. Juveniles were about twice as likely as adult squirrels to be infected and shed higher concentrations of oocysts than adults did, with particularly high levels of infection and shedding being found among juvenile male squirrels. Based on DNA sequencing of a portion of the 18S small-subunit rRNA gene, there existed three genotypes of Cryptosporidium species in these populations of squirrels (Sbey03a, Sbey03b, and Sbey03c; accession numbers AY462231 to AY462233, respectively). These unique DNA sequences were most closely related (96 to 97% homology) to porcine C. parvum (AF115377) and C. wrairi (AF115378). Inoculating BALB/c neonatal mice with up to 10,000 Sbey03b or Sbey03c fresh oocysts from different infected hosts did not produce detectable levels of infection, suggesting that this common genotype shed by California ground squirrels is not infectious for mice and may constitute a new species of Cryptosporidium.

Prevalence of Escherichia coli O157:H7 in white-tailed deer from Louisiana.

Escherichia coli O157:H7 (EC O157) is an important zoonosis. White-tailed deer (Odocoileus virginianus) have been implicated in transmission of this bacterium to humans and have been suggested as reservoirs that might affect carriage in cattle populations. Our study objectives were to estimate prevalence of EC O157 in feces of hunter-harvested deer and to describe fecal shedding patterns in a captive herd sampled over 1 yr. Prevalence of EC O157 in hunter-harvested deer was 0.3% (n = 338). In August 2001, EC O157 was detected in one of 55 deer (1.8%) from the captive herd. Prevalence over the 1-yr period was 0.4% (n = 226). Escherichia coli O157:H7 was rarely isolated from hunter-harvested deer during the winter. We could not describe a seasonal shedding pattern based on one positive sample in the captive herd. These data do not support a prominent role of deer as a reservoir for EC O157 for cattle or humans.

Prevalence of Shiga-toxigenic Escherichia coli O157:H7 in adult dairy cattle.

To describe shiga-toxigenic Escherichia coil O157:H7 (STEC O157:H7) fecal shedding prevalence, seasonal fecal shedding patterns, and site-specific prevalence from the oral cavity, skin, and feces of dairy cattle. Cross-sectional study. Adult dairy cattle from 13 herds in Louisiana. Samples were cultured for STEC O157 by use of sensitive and specific techniques, including selective broth enrichment, immunomagnetic separation, monoclonal antibody-based O:H enzyme immunoassay serotyping, and polymerase chain reaction virulence gene characterization. Point estimates and 95% confidence intervals were calculated for fecal shedding prevalence as well as site-specific prevalence from the oral cavity, skin, and feces. Logistic regression was used to assess seasonal variation and differences at various stages of lactation with respect to fecal shedding of STEC O157 in cattle sampled longitudinally. Summer prevalence in herds in = 13) was 38.5%, with a cow-level prevalence of 6.5%. Among positive herds, prevalence ranged from 3% to 34.6%. Samples from 3 of 5 herds sampled quarterly over 1 year yielded positive results for STEC O157. In herds with STEC O157, an increase in cow-level prevalence was detected during spring (13.3%) and summer (10.5%), compared with values for fall and winter. Site-specific prevalences of STEC O157:H7 from oral cavity, skin, and fecal samples were 0%, 0.7%, and 25.2%, respectively. Our data indicated that STEC O157:H7 was commonly isolated from dairy cows in Louisiana, seasonally shed, and isolated from the skin surface but not the oral cavity of cows.

Enteric and nasal shedding of bovine torovirus (Breda virus) in feedlot cattle.

To assess fecal and nasal shedding patterns of bovine torovirus (BoTV) in cattle at time of arrival and periodically throughout the first 21 days after arrival at a feedlot. 57 steers. Fecal and nasal-swab samples collected on days 0, 4, 14, and 21 after arrival were tested for BoTV, using ELISA. A subset of samples from calves testing positive and negative for BoTV was analyzed, using reverse transcriptase-polymerase chain reaction (RT-PCR). Paired serum samples were collected on days 0 and 21 and tested for BoTV antibodies, using a hemagglutination inhibition assay. Overall rate of fecal shedding of BoTV was 21 of 57 (37%) by ELISA and 40 of 42 (95%) by RT-PCR with peak shedding on day 4. Diarrhea was more common in calves shedding BoTV than those not shedding the virus (odds ratio, 1.72). Overall rate of nasal shedding of BoTV was 15 of 57 (26%) by ELISA and 42 of 42 (100%) by RT-PCR, with peak shedding on day 0. Specificity of the RT-PCR product was confirmed by sequence analysis. Approximately 93% of the calves seroconverted to BoTV (> 4-fold increase in titer). Differences were not detected between calves shedding BoTV and nonshedders in relation to disease and treatments, perhaps because of the low number of cattle in the study. This study confirmed BoTV infections in feedlot cattle, including BoTV antigen and viral RNA in nasal secretions, and the shedding pattern during the first 21 days after arrival in a feedlot.

Fecal Shedding and Antimicrobial Susceptibility of Selected Bacterial Pathogens and a Survey of Intestinal Parasites in Free-Living Waterfowl

Free-living waterfowl residing in metropolitan parks in central Ohio were surveyed for the fecal shedding and antimicrobial susceptibility patterns of Campylobacter jejuni, Escherichia coli, Salmonella spp., and Pasteurella multocida. In addition, a survey for intestinal parasites was also conducted in these same waterfowl to determine parasite burdens in free-living waterfowl. Prevalences of 67%, 50%, and 0.2% of E. coli, C. jejuni, and Salmonella spp., respectively, were observed for all waterfowl species. Pasteurella multocida was not isolated from the sampled population. Salmonella java was isolated from one mallard duck. Statistically, there was a significantly higher E. coli isolation rate for mallard ducks than for Canada geese, but no difference was observed for C. jejuni isolation rates between waterfowl species. Antimicrobial susceptibility testing was conducted via the disk diffusion method and multidrug resistance was exhibited for penicillin G, lincomycin, vancomycin, erythromycin, and bacitracin. In addition, the prevalence of endoparasites in these sampled waterfowl ranged from 5% to 66%. Protozoan oocysts were most prevalent followed by nematode ova. No trematode or cestode ovum was recovered from this sampled population.

Effects of Antibiotic Regimens on the Fecal Shedding Patterns of Pigs Infected with Salmonella Typhimurium

An experiment was conducted to determine (i) the effects of antibiotic regimens on the shedding patterns of pigs infected with Salmonella Typhimurium and (ii) whether antibiotic resistance increases the incidence of pathogen shedding. The experiment involved 48 50-day-old pigs challenged with Salmonella Typhimurium and receiving one of four antibiotic regimens including (i) intramuscular injection of ceftiofur sodium followed by inclusion of oxytetracycline in the feed; (ii) apramycin in the feed for 14 days followed by oxytetracycline; (iii) carbadox in the feed until pigs reached 35 kg followed by oxytetracycline; (iv) no antibiotics (control). Fecal samples were collected preinoculation, 2 and 4 days postinoculation (DPI) and at weekly and biweekly intervals thereafter to determine shedding patterns. Salmonella Typhimurium isolates from 2, 4, 7, 21, 42, and 70 DPI were analyzed for antibiotic resistance. A time effect (P < 0.05) was observed, indicating that the proportion of isolates resistant to at least one antibiotic varied over time. Overall resistance was determined to be 46% at 2 DPI and increased significantly (P < .05) thereafter. Treatment × time and antibiotic × time interactions were also observed (P < 0.05) as the percentage of isolates resistant to each test antibiotic increased over time. In no case did the development of antibiotic resistance result in an increased incidence of shedding of the original inoculate. The incidence of shedding was reduced in pigs receiving the apramycin–oxytetracycline treatment, when compared to control pigs; however, no differences were observed between antibiotic treatments.

Fecal shedding of feline coronavirus in adult cats and kittens in an Abyssinian cattery

Objective To determine patterns of fecal shedding of feline coronavirus (FCV) by cats, age at which kittens first began to shed FCV in their feces, and whether there was any relationship between fecal shedding of FCV and serum antibody titers in adult cats or kittens. Design Prospective observational study. Animals 15 adult cats and 18 kittens from a single cattery. Procedure Blood and fecal samples were collected from adult cats every other month for 13 months. Serum FCV antibody titers were measured by use of an indirect immunofluorescence assay. A reverse-transcriptase, nested polymerase chain reaction assay was used to detect FCV in feces. Blood and fecal samples were collected from kittens at approximately 2-week intervals from 3 weeks to 15 weeks of age. Results Adult cats shed FCV intermittently. All adult cats shed virus in their feces at least once during the year, and 4 of 15 shed virus &gt; 75% of the time. Serum antibody titer was not significantly associated with shedding of FCV. For the kittens, median age at the time FCV was first detected in feces was 67 days (range, 33 to 78 days). All except 1 of the kittens was found to be shedding virus in their feces before or at the time of seroconversion. Conclusions and Clinical Relevance Results suggest that serum FCV antibody titers are not a good indicator of shedding of FCV in the feces. Kittens may shed FCV in their feces before they seroconvert, and all kittens in a cattery in which FCV infection is endemic may be infected before 12 weeks of age. (J Am Vet Med Assoc 1999;215:948–951)

Patterns of feline coronavirus infection and fecal shedding from cats in multiple-cat environments

Objective— To determine, by use of a reverse transcriptase-polymerase chain reaction (RT-PCR) test, patterns of fecal shedding of feline coronavirus among cats. Design— Prospective observational study. Animals— 275 purebred cats from 6 private catteries and 40 specific-pathogen-free (SPF) laboratory-reared cats. Procedure— 40 SPF cats were experimentally inoculated with crude fecal extract containing feline enteric coronavirus (FECV). Fecal and plasma samples were collected every 4 days and evaluated by use of RT-PCR and indirect immunofluorescence assays, respectively, to correlate RT-PCR results with fecal infectivity and to determine patterns of FECV shedding and anti-FECV IgG production in acutely infected cats. The 275 cats in private catteries were monitored for 1 year. Fecal and blood samples were collected every 1 to 3 months and assayed by use of RT-PCR and serologic tests to determine patterns of coronavirus shedding and cofactors for high frequency shedding. Results— Results of the RT-PCR test in SPF cats were directly correlated with fecal extract infectivity. Overall, 370 of 894 (41%) fecal samples collected from cattery and shelter cats contained infectious levels of coronavirus. Of 121 cats from which multiple samples were collected, 11 never shed virus and 35, 65, and 10, respectively, shed virus with low, moderate, and high frequency. High frequency shedding was associated with age and cattery of origin, but not with sex or concurrent disease. Stress associated with parturition and lactation did not induce shedding in queens. Kittens did not shed coronavirus before they were 10 weeks old, even when nursed by shedding mothers. Clinical Implications— A large proportion of cats in multiple-cat environments shed coronavirus at any given time, but most undergo cycles of infection and shedding, recovery, and reinfection. Infection is acquired from chronically shedding cats and from infectious cats undergoing transient primary infection. Chronically shedding cats cannot be identified on the basis of antibody titer or signalment, but must be identified on the basis of the results of serial fecal RT-PCR tests. (J Am Vet Med Assoc 1997;210:1307–1312)

Viral Shedding And Fecal Iga Response After Norwalk Virus Infection

Protection is not conferred by preexposure to Norwalk virus (NV). By use of an ELISA with baculovirus-expressed recombinant NV (rNV) capsid protein, the pattern of NV fecal shedding and the protective effect of rNV-specific fecal IgA (flgA) were investigated in volunteers who were repeatedly challenged with NV. After the first challenge, ill volunteers were significantly more likely than well volunteers to have NV antigen in their stool (P < .05). After challenge, antigen shedding was detected on days 1-13; ill volunteers shed the antigen longer (P = .02). A higher prechallenge rNV-specific flgA geometric mean titer was found in ill compared with well volunteers (P < .05) and in infected versus noninfected volunteers (P < .05). NV shedding was common after infection and was present up to 2 weeks after challenge. Preexisting rNV-specific flgA, like serum IgG, is not protective and may be a marker for symptomatic disease.

Development of nasal, fecal and serum isotype-specific antibodies in calves challenged with bovine coronavirus or rotavirus

Unsuckled specific pathogen free calves were inoculated at 3–4 weeks of age, either intranasally (IN) or orally (O) with bovine coronavirus or O plus IN (O/IN) or O with bovine rotavirus. Shedding of virus in nasal or fecal samples, and virus-infected nasal epithelial cells were detected using immunofluorescent staining (IF), ELISA or immune electron microscopy (IEM). Isotype-specific antibody titers in sera, nasal and fecal samples were determined by ELISA. Calves inoculated with coronavirus shed virus in feces and virus was detected in nasal epithelial cells. Nasal shedding persisted longer in IN-inoculated calves than in O-inoculated calves and longer than fecal shedding in both IN and O-inoculated calves. Diarrhea occurred in all calves, but there were no signs of respiratory disease. Calves inoculated with rotavirus had similar patterns of diarrhea and fecal shedding, but generally of shorter duration than in coronavirus-inoculated calves. No nasal shedding of rotavirus was detected. Peak IgM antibody responess, in most calves, were detected in fecal and nasal speciments at 7–10 days post-exposure (DPE), preceeding peak IgA responses which occurred at 10–14 DPE. The nasal antibody responses occurred in all virus-inoculated calves even in the absence of nasal shedding of virus in rotavirus-inoculated calves. Calves inoculated with coronavirus had higher titers of IgM and IgA antibodies in fecal and nasal samples than rotavirus-inoculated calves. In most inoculated calves, maximal titers of IgM or IgA antibodies correlated with the cessation of fecal or nasal virus shedding. A similar sequence of appearance of IgM and IgA antibodies occurred in serum, but IgA antibodies persisted for a shorter period than in fecal or nasal samples. Serum IgG 1 antibody responses generally preceeded IgG 2 responses and were predominant in most calves after 14–21 DPE.