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Biomedical subjects

D W Dreesen

Publications and source records attributed to D W Dreesen.

At least 19 recordsLinked to original sources

Epidemiologic features of Campylobacter jejuni isolated from poultry broiler houses and surrounding environments as determined by use of molecular strain typing.

OBJECTIVE: To genetically type Campylobacter jejuni isolates from broiler houses or the external environment to identify the source of Campylobacter organisms in broiler chickens. SAMPLE POPULATION: Environmental samples associated with broiler chickens, in commercial grow-out houses. PROCEDURE: Polymerase chain reaction (PCR) was used to amplify flaB, and the amplicon was digested with Sau3A to create a restriction fragment length polymorphism assay; PCR was also used to detect a transcribed spacer region in the 23S rRNA gene. RESULTS: Isolates possessing a 23S spacer region were more prevalent outside broiler houses than inside. Houses that had previously contained chickens or lacked biosecurity procedures were more likely to contain isolates possessing the 23S spacer. One house contained only isolates possessing the spacer, whereas an adjacent house contained only isolates lacking the spacer. The flaB type detected in broiler houses was different from the type detected in the environment; however, many isolates within the broiler houses contained untypable flaB genotypes. CONCLUSIONS AND CLINICAL RELEVANCE: Most isolates from within houses were genetically distinct from isolates from outside houses that were examined by bacteriologic culture, suggesting an undetected source of C jejuni. Detection of isolates containing the 23S spacer appeared to be an indicator of environmental contamination of the houses. The observation of completely different C jejuni genetic types simultaneously within adjacent houses suggests that some types do not compete successfully during the grow-out period. In addition, the diversity of genotypes identified within broiler houses indicates the complexity of the ecologic features of C jejuni in the chicken environment.

Animals↗

Purified Chick Embryo Cell Culture Rabies Vaccine: interchangeability with Human Diploid Cell Culture Rabies Vaccine and comparison of one versus two-dose post-exposure booster regimen for previously immunized persons.

The equivalence and interchangeability of Purified Chick Embryo Cell Culture Rabies Vaccine (PCECV) to Human Diploid Cell Culture Rabies Vaccine (HDCV) and the immunogenicity of a reduced post-exposure regimen with PCECV was investigated. Statistical analyses revealed no difference (P</=0.05) between the geometric mean titers (GMT) on day 49 of subjects that received PCECV or HDCV. In Year 2, subjects were boosted with one or two dose(s) of PCECV. No significant difference (P</=0.05) was detected between the GMT of the two groups on days 7 and 365 post-booster. Subjects that received HDCV initially developed an adequate anamnestic response to PCECV. On day 21 post-booster, the GMT of subjects that received two boosters was higher (151.6 IU/ml) than those that received one booster (120.9 IU/ml). However, this difference may not be clinically significant.

Adult↗

Molecular epidemiology of Campylobacter jejuni in broiler flocks using randomly amplified polymorphic DNA-PCR and 23S rRNA-PCR and role of litter in its transmission.

Poultry has long been cited as a reservoir for Campylobacter spp., and litter has been implicated as a vehicle in their transmission. Chicks were raised on litter removed from a broiler house positive for Campylobacter jejuni. Litter was removed from the house on days 0, 3, and 9 after birds were removed for slaughter. Chicks were raised on these three litters under controlled conditions in flocks of 25. None of these birds yielded C. jejuni in their cecal droppings through 7 weeks. Two successive flocks from the same Campylobacter-positive broiler house were monitored for Campylobacter colonization. Campylobacter jejuni prevalence rates were determined for each flock. Randomly amplified polymorphic DNA (RAPD)-PCR and 23S rRNA-PCR typing methods were used to group isolates. A high prevalence (60%) of C. jejuni in flock 1 coincided with the presence of an RAPD profile not appearing in flock 2, which had a lower rate of prevalence (28%). A 23S rRNA-PCR typing method was used to determine if strains with different RAPD profiles and different prevalence rates contained different 23S sequences. RAPD profiles detected with higher prevalence rates contained a spacer in the 23S rRNA region 100% of the time, while RAPD profiles found with lower prevalence rates contained an intervening sequence less than 2% of the time. Data suggest varying colonizing potentials of different RAPD profiles and a source other than previously used litter as a means of transmission of C. jejuni. These molecular typing methods demonstrate their usefulness, when used together, in this epidemiologic investigation.

Animal Husbandry↗

Current recommendations for the prophylaxis and treatment of rabies.

Once onset of clinical rabies develops in an individual, death is inevitable. Thus, it is imperative that, for persons exposed or potentially exposed to rabies virus, prophylaxis must be instituted as soon as possible following the exposure. Local wound management is an essential part of postexposure rabies prophylaxis. Exposed persons should receive a recommended series of a tissue culture or cell culture origin vaccine. The number of doses and route of vaccination differ in various regions of the world and are discussed in the text. The administration of a rabies immune globulin is generally recommended in conjunction with the first dose of the rabies vaccine. Nerve tissue origin vaccines, although used extensively in some parts of the world, are not recommended if cell or tissue culture vaccines are available. Decision trees are presented in the text to aid in determining if rabies vaccine is necessary following a known or presumed exposure to the virus, along with a table outlining the various rabies vaccines available in the World. Rabies pre-exposure immunisation is recommended for those individuals at risk of exposure to the virus. Pre-exposure prophylaxis consists of 3 doses of an approved rabies vaccine administered either intramuscularly or intradermally on days 0, 7, and 21 or 28 with periodic booster doses or titre determination depending on the level of risk of potential exposure to the virus.

Decision Making↗

A global review of rabies vaccines for human use.

Rabies is one of the oldest known diseases of mankind, yet it has been only slightly more than 100 years since Pasteur developed the first vaccine for post-exposure treatment. Since this first crude nerve tissue vaccine, numerous other rabies vaccines for human use have been developed and used with varying degrees of effectiveness and safety. When used appropriately, new cell culture vaccines provide nearly 100% protection with a high degree of safety: yet over 40,000 people world-wide die from rabies each year. Several pre- and post-exposure controlled vaccine trials and clinical studies have shown that the purified chick embryo cell (PCEC) vaccine, Rabipur, is as safe and effective as the rabies human diploid cell vaccine (HDCV), which is currently considered the gold standard. Additionally, PCEC vaccine does not result in immune-mediated hypersensitivity reactions following booster doses seen in about 6% of those receiving HDCV boosters following an initial series of HDCV.

Animals↗

Pathogenesis of experimentally induced rabies in domestic ferrets.

OBJECTIVE: To determine susceptibility, incubation and morbidity periods, clinical signs, serologic response, and excretion of virus in domestic ferrets inoculated with rabies virus. ANIMALS: 55 domestic ferrets. PROCEDURE: 5 groups of 10 ferrets were inoculated with rabies virus, IM, at doses of 10(5.5) to 10(1.5) median mouse intracerebral lethal dose. Ferrets were observed and behavior was recorded. Rectal temperature, body weight, and samples from the oral cavity and samples of saliva and blood were obtained. Virus isolation was attempted, using intracranial mouse inoculation and cell culture. Virus neutralizing antibodies were determined by rapid fluorescent focus inhibition test. Ferrets were euthanatized immediately if clinical signs were severe. Rabies was confirmed by direct immunofluorescent antibody test. RESULTS: Mean incubation period was 33 days (range, 16 to 96 days). Clinical signs included ascending paralysis, ataxia, cachexia, bladder atony, fever, hyperactivity, tremors, and paresthesia. Mean morbidity period was 4 to 5 days (range, 2 to 10 days). Virus antigen was detected in brain tissue from all clinically rabid ferrets. Ferrets given the highest viral dose were euthanatized and had VNA; ferrets receiving the next dilution also were euthanatized, but only 4 had seroconverted. Of 17 ferrets that survived, 5 seroconverted. Survivors remained clinically normal except for 1 that recovered with severe paralytic sequelae. Rabies virus was isolated from the salivary gland of 1 ferret that was euthanatized. CONCLUSIONS AND CLINICAL RELEVANCE: Rabies should be considered as a differential diagnosis in any ferret that has acute onset of paralysis or behavioral changes and a condition that rapidly deteriorates despite intense medical intervention.

Animals↗

Safety and immunogenicity of Lyssavac Berna human diploid cell rabies vaccine in healthy adults.

A clinical trial testing the safety and immunogenicity of a newly developed human diploid cell rabies vaccine (Lyssavac-HDC) was conducted on subjects at three colleges of veterinary medicine in the United States. Lyssavac-HDC is a sterile lyophilized vaccine containing no antibiotics or preservatives and is administered intramuscularly as a 0.5 ml dose of vaccine containing at least 2.5 i.u. of rabies inactivated antigen per dose. Subjects were given either a three dose pre-exposure series (days 0, 7, and 28), followed by one booster dose of vaccine (day 360); or a five dose simulated post-exposure series of injections (days 0, 3, 7, 14, and 28). All subjects in the post-exposure and pre-exposure groups possessed adequate levels of rabies neutralizing antibody (> or = 5) when tested on day 14 and day 28, respectively. Subjects in the pre-exposure group demonstrated a vigorous anamnestic response after the administration of one booster dose of vaccine on day 360. The type and severity of local and systemic reactions observed were comparable to other primary cell culture rabies vaccines. Significantly, there were no type III hypersensitivity reactions reported in subjects previously immunized with Lyssavac-HDC after the administration of a booster dose of vaccine on day 360.

Adult↗

A simulation of microbial competition in the human colonic ecosystem.

Many investigations of the interactions of microbial competitors in the gastrointestinal tract used continuous-flow anaerobic cultures. The simulation reported here was a deterministic 11-compartment model coded by using the C programming language and based on parameters from published in vitro studies and assumptions were data were unavailable. The resource compartments were glucose, lactose and sucrose, starch, sorbose, and serine. Six microbial competitors included indigenous nonpathogenic colonizers of the human gastrointestinal tract (Escherichia coli, Enterobacter aerogenes, Bacteroids ovatus, Fusobacterium varium, and Enterococcus faecalis) and the potential human enteropathogen Salmonella typhimurium. Flows of carbon from the resources to the microbes were modified by resource and space controls. Partitioning of resources to the competitors that could utilize them was calculated at each iteration on the basis of availability of all resources by feeding preference functions. Resources did not accumulate during iterations of the model. The results of the computer simulation of microbial competition model and for various modifications of the model. The results were based on few measured parameters but may be useful in the design of user-friendly software to aid researchers in defining and manipulating the microbial ecology of colonic ecosystems as relates to food-borne disease.

Carbohydrates↗

Virulence determinants invA and spvC in salmonellae isolated from poultry products, wastewater, and human sources.

The presence of two virulence foci, invA and spvC, in Salmonella isolates obtained from poultry, wastewater, and human sources was determined. All isolates (n = 245) were positive for the invA gene sequence. Differences in degree of invasiveness were apparent with the Madin Darby canine kidney cell line, as only 79 of 159 randomly selected isolates (49.7%) tested were invasive at > 0.1% of the inoculum. 25% were invasive between 0.1 and 1.0% of the inoculum, and 24.5% were invasive at > 1.0% of the inoculum. There was a significant correlation between degree of invasion and source from which the isolate was recovered but no correlation between geographic origin of poultry isolates and degree of invasion. Only 37 of 245 isolates (15.1%) hybridized with the spvC DNA probe. All isolates that were recovered from a commercial egg production environment and chicken eggs and whose sequences exhibited homology with the spvC gene sequence were determined to be either Salmonella enteritidis PT 23 or PT 13. The sequences of few isolates from ceca and none from wastewater or humans demonstrated homology with the spvC gene.

Animals↗

Risk factors for systemic hypersensitivity reactions after booster vaccinations with human diploid cell rabies vaccine: a nationwide prospective study.

To determine the incidence of and risk factors for adverse reactions following the boosters, we conducted a nationwide prospective study of persons receiving pre-exposure booster vaccination with human diploid cell rabies vaccine (HDCV). Persons who had previously received three pre-exposure doses of HDCV and whose rabies neutralizing antibody titres were < or = 1:5 were enrolled in the study if they stated that they intended to receive a booster. Of the 98 persons enrolled in the study, 40 (41%) were in risk groups for whom boosters are not recommended. Three (3%) of 98 developed generalized urticaria or wheezing within 1 day of receiving boosters and three others (3%) developed urticaria 6 to 14 days after the booster. No differences were found between individuals with reactions (either type) and those with no adverse reaction according to age, gender, occupation, history of previous allergies, or time since or route of primary vaccination. Reactions were somewhat more common among persons who received primary vaccinations by the intramuscular route (i.m.) and booster vaccinations by the intradermal route (i.d.) (3/15, 20%) or primary vaccinations i.d. and booster vaccinations i.m. (2/10, 20%), and somewhat less common among persons who received both these vaccinations i.d. (1/52, 2%) or i.m. (0/7). The number of persons who develop allergic reactions may be minimized by administering vaccinations only when vaccination is strictly indicated. The influence of the route of primary and booster vaccinations on the development of reactions deserves further study.

Adult↗

Prevalence of toxoplasmosis in swine from Iowa.

Of swine from 104 herds, 2,616 were tested for antibodies against Toxoplasma gondii, using an ELISA. Data were analyzed according to swine type, herd size, facility type, and season. The true prevalence of toxoplasmosis was estimated as 5.4% among finishing swine and 11.4% among sows and gilts. Herds with less than 100 breeding swine were significantly (P less than 0.05) more likely to be infected than were herds with greater than or equal to 100 breeding swine. The rate of seropositivity in breeding swine was approximately the same in infected herds, regardless of herd size. Herds with finishing swine maintained in total confinement were as likely to become infected as were herds maintained in other types of facilities, but infected herds with finishing swine maintained in confinement appeared to have a lower in-herd prevalence than did herds maintained in other types of facilities (P = 0.09). Seasonal effects were not observed, and prevalence remained relatively constant throughout the year.

Age Factors↗

Western blot analyses and LD50 determinations of Toxoplasma gondii isolates.

Western blot analysis of tachyzoite detergent extracts revealed striking similarities and only minor differences in the antigenic profiles of four isolates, including one new isolate of Toxoplasma gondii. At least nine common protein bands with molecular weights ranging from 14,000-108,000 were recognized by all antitoxoplasma antisera. Differences existed primarily between molecular weights 28,000 and 33,000. The LD50 determinations showed that strains of laboratory mice were affected differently by the various Toxoplasma isolates used in this study. Results indicate a need for further investigations into whether there are true strain differences of Toxoplasma gondii or simply different isolates of the same strain of this single species in the genus Toxoplasma.

Animals↗

Two-year comparative trial on the immunogenicity and adverse effects of purified chick embryo cell rabies vaccine for pre-exposure immunization.

The human diploid cell rabies vaccine (HDCV) has been shown to be highly immunogenic when used for pre-exposure immunization. However, the high cost of the product and the adverse reactions seen following booster doses of HDCV have limited its use. A purified chick embryo cell (PCEC) rabies vaccine was compared with the HDCV by two routes of administration for reactogenicity, antibody response, duration of antibody, and anamestic response to boosters over a 2 year period. The study showed that the two vaccines were comparable in their immunogenicity and reactogenicity after initial three dose series. No adverse reactions were noted following the 2 year booster with PCEC. The PCEC can be produced at less than one-half the cost of the HDCV.

Adult↗