Long-term outcome after thrombectomy in acute myocardial infarction.

BACKGROUND: Current data appear in favour of thrombectomy for ST-elevation myocardial infarction (STEMI). However, information on long-term outcome after thrombectomy is limited. We performed a retrospective long-term study to assess the risk of cardiac re-hospitalizations and survival after discharge from the index hospitalization for STEMI. METHODS: Patients originally randomized to percutaneous coronary intervention (PCI) with thrombectomy vs. standard PCI were included in a retrospective long-term observational study. The primary study endpoint was the combined risk for all-cause death or cardiac re-hospitalization after index discharge under optimal medical therapy. The cumulative number of cardiac hospitalization days and ventricular remodelling assessed by echocardiography and plasma biomarkers were secondary endpoints. RESULTS: Of 94 STEMI patients who had been randomized between 11/2000 and 03/2003, 89 patients consented to long-term follow-up. A total of 43 patients had been allocated to thrombectomy and 46 to standard primary PCI. The minimum follow-up time was 1115 days. There was a significantly lower risk for death or cardiac re-hospitalization for patients of the thrombectomy group (hazard ratio = 0.69, 95% CI: 0.49-0.98, P = 0.036). The incidence of recurrent myocardial infarction was not different (P = 0.343). No differences in cardiac remodelling were detected by echocardiography, with the exception that heart-type fatty acid binding protein at 53.2 +/- 17 months was lower in the thrombectomy group (P = 0.045). CONCLUSION: Thrombectomy in STEMI may decrease the long-term risk for death or cardiac re-hospitalization.

Immunological surveillance in a pseudorabies quarantined herd using gilts and their progeny as sentinels.

Specific pathogen free gilts and their progeny were evaluated to use as sentinels in a pseudorabies virus (PRV) infected herd by immunologically monitoring for PRV seroconversions. Time intervals targeted were pre- and post-PRV vaccinations, herd exposure, and farrowing to finishing. Post-PRV vaccinations, gilts showed low PRV lymphocyte stimulation and humoral responses. Following herd exposure, control gilts PRV seroconverted and PRV vaccinated gilts increased (2 to 4 times) in virus neutralization (VN) titers. Sixty-seven percent (4/6) of the progeny from a control gilt were PRV seropositive at finishing. Progeny from PRV vaccinated gilts were depleted of passive immunity by week 7, and were seronegative until week 9. At finishing 47% (14/30) of them were PRV seropositive indicating exposure to PRV. The VN test was not sensitive enough to detect weak positive serums, noted as positives by latex agglutination (LA) test, ELISA, and Western blots. The gilts and progeny detected PRV, respectively, in the herd housing quarters and in the farrow to finish facilities. A strategy for future sentinel experimental surveillances using primarily the LA test is proposed.

Serological evidence of infection of dogs and man in Nigeria by lyssaviruses (family Rhabdoviridae).

A survey was conducted for serum neutralizing antibodies against 3 members of the Lyssavirus group (rabies, Lagos bat and Mokola viruses) in Nigerian dogs and humans. Of 463 unvaccinated dogs sampled, 142 (30.7%) had antibodies against rabies; 39.2% of the stray dogs were positive. Of 241 dogs tested, 17.4% had antibodies against Mokola virus and 5.8% against Lagos bat virus. 28.6% of human samples tested had antibodies against rabies and, of 158 human samples tested, 12 (7.5%) had antibodies against Mokola virus and 4 (2.5%) had antibodies against Lagos bat virus.

Ecology of dogs in the Central Philippines in relation to rabies control efforts.

Rabies is endemic in dogs but has no other host as reservoir in the Philippines. Essential to programmes of rabies control is an understanding of the ecology of dogs and their relationships to human society. In the central Philippines, where this study was conducted before and during rabies control efforts, most households in rural 'barangays' or communities owned one or more dogs which served as guards, as scavengers and, in some, as a source of meat--but not as pets to be handled and played with. A second important category of dogs comprised those which foraged semi-self-sufficiently but were recognized by the barangay residents as belonging to the community. The number of these dogs was determined by the carrying capacity of the community, but their population was dependent upon cast-off owned dogs as their fecundity was below maintenance levels. Killing of any dogs, except for meat or in the event of suspicion of rabies, was of low social acceptance. In urban centres, upper class residents owned dogs as guards or pets but their employees, who often lived within their compounds, related to their dogs as did rural residents. Middle class families maintained greater control over their dogs. In lower class urban districts, a continual influx of dogs which on occasion were incubating rabies, plus the large size of many such districts, enabled them to serve as continual foci of infection. In this setting, rabies control was most effectively achieved by teams of vaccinators going house to house, capturing and injecting all dogs whether owned or belonging to the community. The immunization of 80% or more of the dogs was readily achieved and brought rabies under complete control.

The effect of storage time on isolation of Leptospira interrogans from bovine kidneys.

Kidney tissues from 20 cattle infected with Leptospira interrogans serovars hardjo, pomona, or grippotyphosa were cultured on the day of slaughter and 3, 6, and 8 days later to examine the effect of storage time on the recovery of leptospires by conventional culture methods. Leptospires were isolated from 85% of infected bovine kidney tissues cultured on day 1, and from 95%, 90%, and 90% of kidney tissues stored in transport medium at 4 C for 3, 6, and 8 days, respectively, prior to inoculation of culture media.

A study comparing the immunologic responses of swine to pseudorabies viral antigens based on the ELISA, serum virus neutralization, and latex agglutination tests.

A study of pseudorabies virus (PRV)-vaccinated pigs comparing the immune responses detected by the latex agglutination test (LAT) with responses detected by other routine tests for pseudorabies antibodies indicated that LAT was more sensitive than either the enzyme-linked immunosorbent assay (ELISA) or the serum virus neutralization test (SVNT). The LAT detected antibodies sooner than ELISA and SVNT in unvaccinated pigs after challenge with virulent PRV. The specificities of the 3 tests were found to be near 100%. The LAT is a good alternative to SVNT or ELISA for detection of PRV-specific antibodies.

A current assessment of the role of porcine parvovirus as a cause of fetal porcine death.

One hundred one litters containing 1 or more dead porcine fetuses were collected at an Iowa abattoir during a 2-month interval and examined for evidence of viral infection. Each of 1,137 fetuses (302 dead, 835 alive) of these litters was tested for porcine parvovirus (PPV) antigens by direct immunofluorescence microscopy (FA) of fetal lung. Antigens of PPV were detected in the lungs of most of the fetuses of 11 of the litters. The 11 FA-positive litters contained 105 dead (100 FA-positive) and 14 live (12 FA-positive) fetuses. Infectious PPV was isolated from 10 of the 11 FA-positive litters and from 3 of the 90 FA-negative litters. No cytopathogenic agents other than PPV were isolated from any of the litters. Eleven of 101 (11%) litters examined and 100 of 302 (33%) dead fetuses examined were FA positive for viral antigen, indicating that PPV remains as a major cause of porcine fetal death.

Porcine leptospirosis in Iowa.

The epidemiology of leptospirosis in Iowa swine was examined on the basis of serologic results and herd data from 55 herds in the National Animal Health Monitoring System (NAHMS) program and culture results and histories from 578 cases of reproductive failure submitted to the Iowa Veterinary Diagnostic Laboratory during a 3-year period. Thirty-eight percent of sera from NAHMS herds contained antibodies against 1 or more of 12 leptospira antigens. Leptospires were isolated from 9 (1.6%) of 578 cases of reproductive failure. Seven (78%) of the isolates were identified as Leptospira interrogans serovar kennewicki and 2 (22%) as serovar grippotyphosa. In 7 herds from which leptospires were isolated, attack rates ranged from 1% to 84%. Clinical leptospirosis, characterized by reproductive failure and confirmed by isolation of leptospires, was sporadic. No significant differences in farrowing averages and reproductive problems were observed between vaccinated and nonvaccinated NAHMS herds or between herds with higher (43-63%) or lower (14-40%) percentages of animals that were serologically positive against serovar bratislava.

The epidemiology of toxoplasmosis on Iowa swine farms with an emphasis on the roles of free-living mammals.

Multiparous sows from 19 central Iowa swine farms were tested for antibodies against Toxoplasma gondii by the modified direct agglutination test. Antibody titers of 1:32 or greater were considered positive. Rodents, domestic cats, opossums (Didelphis virginiana), raccoons (Procyon lotor) and striped skunks (Mephitis mephitis) were live-trapped on each farm and similarly tested for antibodies. The overall prevalence of T. gondii antibodies in the species tested was 39/273 (14.3%) swine, 31/74 (41.9%) cats, 2/588 (0.3%) house mice (Mus musculus), 0/21 mice of the genus Peromyscus, 0/9 Norway rats (Rattus norvegicus), 1/34 (2.9%) opossums, 4/14 (28.6%) raccoons and 2/7 (28.6%) striped skunks. The overall prevalence was significantly greater in adult cats versus juvenile cats, adult male cats versus adult female cats, and adult raccoons versus juvenile raccoons. The prevalence of T. gondii antibodies in sows was compared with the prevalence in each non-swine species on a farm basis in order to identify existing associations. The prevalence in sows (and each of the non-swine species) was also analyzed on a farm basis for association with farm characteristics or swine management practices, including the degree of confinement of swine, population size and average parity of breeding female swine, estimated cat population size, and estimated mouse and rat abundance. Average titers of seropositive animals were compared on a species basis. The prevalence in sows which were totally and continuously confined was lower than that in sows which were not totally and continuously confined. The prevalence in sows from farms with an average parity of less than 2.0 was significantly lower than that in sows from farms with an average parity of 2.0 or greater. These results suggested that the prevalence of T. gondii antibodies in swine increased with age and that prevalence in swine could be reduced through total confinement. No associations could be established between prevalence in sows and prevalence in non-swine species or other farm characteristics/swine management practices. However, the high prevalence of T. gondii antibodies in cats suggested that fecal contamination of the environment by cats may be the most significant source of toxoplasmosis for swine. The extremely low prevalence of T. gondii antibodies in house mice suggested that this species was not an important source of T. gondii for swine in Iowa.

Influence of environmental factors upon the survival of Aujeszky's disease virus.

The survival of Aujeszky's disease (pseudorabies) virus outside the living host was found to be dependent on pH level and temperature. Virus inactivation occurred at a rate varying from 0.04 log10 per day at 4 degrees C to 0.6 log10 per day at 37 degrees C at the optimum pH levels of 6 to 8. Fluctuation of the temperature between 4 degrees C and 37 degrees C had no apparent effect upon the titre of the virus. At a steady temperature of -13 degrees C, the virus was rapidly inactivated at all tested pH levels. For long-term storage it is recommended that the pH should be adjusted to between 6 and 7, that suspensions should be kept at -90 degrees C and that freezing and thawing should be rapid so as to pass through the just subzero temperature zone as quickly as possible. Drying, both on glass and on gelatin, caused inactivation of the virus at all pH levels, as did exposure to ultraviolet light.

Virus survival in the environment.

Viruses pass into the environment from clinically ill or carrier hosts; although they do not replicate outside living animals or people, they are maintained and transported to susceptible hosts. Population concentrations and movement, both animal and human, have been steadily increasing in this century, enhancing transmission of respiratory and enteric viruses and compounding the difficulty of preventing environmental transmission. Studies on environmental survival factors of viruses have been most definitive for polioviruses, foot and mouth disease viruses and Aujeszky's disease virus. In addition, heat resistance studies have been reported on adenoviruses, African swine fever virus and the Norwalk virus. Resistance to disinfectants has been studied for many viruses, including picornaviruses, papovaviruses, reoviruses and retroviruses. Survival of viruses in and on a variety of fomites has been studied for influenza viruses, paramyxoviruses, poxviruses and retroviruses. The subacute spongiform encephalopathy agents, under extensive current studies, are being found to have incredible stability in the environment.

Pseudorabies virus latency and reactivation in vaccinated swine.

Latency and reactivation of pseudorabies virus in swine was studied. Thirty-one pigs were assigned to 5 groups and were given 1 of 4 vaccines; 10 remained unvaccinated controls. All pigs were then challenge exposed with a sublethal dose of virulent pseudorabies virus. One hundred one days after challenge exposure, all pigs were treated with dexamethasone to reactivate the virus. Virus-positive tonsil and nasal mucus isolates were recovered from 29 of the 31 pigs over a 12-day period. Frequency and duration of virus-positivity were significantly (P less than 0.05) and consistently lower among vaccinated pigs than among the unvaccinated controls. It was concluded that vaccination before challenge exposure had little or no effect on the rate of establishment of virus latency, but that vaccination reduced shedding after subsequent reactivation of the virus.

Survey to estimate prevalence of Leptospira interrogans infection in mature cattle in the United States.

A total of 5,142 kidney tissue samples and 5,111 serum samples from mature cattle in 49 states and Puerto Rico were collected at slaughter. Age of cattle ranged from 1 to 16 years (mean, 6.6 years). Leptospires were isolated from 88 (1.7%) kidney tissues, and 2,493 (49%) sera contained antibodies against 1 or more of 12 Leptospira interrogans serovars. Leptospires were observed by immunofluorescence in 41 (0.8%) kidney tissues. Using agglutinin-absorption tests, 73 (83%) isolates were identified as serovar hardjo, 11 (12.5%) as serovar pomona, and 4 (4.5%) as serovar grippotyphosa. By use of restriction endonuclease analysis studies of chromosomal DNA, all isolates differed from reference serovars but were identical to strains previously isolated from cattle or swine in the United States. Of the serovar hardjo isolates, 85% were identical to restriction endonuclease analysis type (genotype) hardjo-bovis A and 11 (15%) were identical to genotype hardjo-bovis B. Serovar pomona isolates were identical to genotypes kennewicki A (64%) or kennewicki B (36%), and serovar grippotyphosa isolates were identical to the RM 52 strain. Isolation rates were significantly (P less than 0.001) higher for beef cattle than for dairy cattle and were higher (P less than 0.001) for bulls than for cows. Combined culture and immunofluorescence results indicated that 2% of mature cattle were renal carriers of leptospires.

Relationships between prevalence of Leptospira interrogans in cattle, and regional, climatic, and seasonal factors.

On the basis of serologic test results and isolation of leptospires from mature cattle, distribution and prevalence of Leptospira interrogans serovars and genotypes were compared by state and region of the United States. Relationships between isolation rate and month of sample collection, mean regional temperature, and mean regional precipitation were examined. Isolation rate and seroprevalence were significantly (P less than 0.001) higher for southeastern, south central, and Pacific coastal regions than for other regions of the United States. Isolates of genotypes hardjo-bovis A and kennewicki A and B, and of serovar grippotyphosa appeared to be randomly distributed. Genotype hardjo-bovis B isolates came from a southern area of the country that extends from Georgia to New Mexico. To the authors' knowledge, this is the first recorded isolation of serovar hardjo from Hawaii. Although significant relationship was not documented between isolation rate and month or season of the year, seroprevalence for summer, fall, and winter was significantly (P less than 0.001) higher than that for spring. Regional isolation rate was related more to mean temperature (r = 0.83; P less than 0.05) than to mean precipitation amount (r = 0.34; P greater than 0.50).

Epidemiologic study of campylobacteriosis in Iowa cattle and the possible role of unpasteurized milk as a vehicle of infection.

Bile samples were collected from 477 Iowa dairy cows and were cultured for thermophilic campylobacters. The prevalence of thermophilic campylobacters in the bile was 15.5%. Campylobacter jejuni and C coli from dairy cattle, chickens, pigs, sheep, and human beings were serotyped to develop host-species profiles. Human and cattle serologic profiles were the most similar, and human and chicken profiles shared several similarities. Epidemiologic data from 168 human cases of campylobacteriosis indicated that 23% of the cases were associated with consumption of unpasteurized milk.

Influence of temperature and age on the recovery of pseudorabies virus from houseflies (Musca domestica).

In laboratory experiments, pseudorabies virus was readily recovered from within the body of houseflies (Musca domestica L) that had ingested the virus. Age of the fly and ambient temperature affected the rate of virus inactivation within the houseflies. Virus half-life in 3-day-old flies was 6.36 hours vs 2.81 hours in flies 8 or 13 days old. Half-life in 5-day-old flies was 12.92 hours at 10 C, 5.95 hours at 20 C, and 2.69 hours at 30 C. Virus half-life in dead flies was 9.06 hours at 10 C, 4.28 hours at 20 C, and 1.71 hours at 30 C. The data did not provide any evidence of virus replication in either living or dead flies.

Survival of pseudorabies virus in aerosol.

The survival of pseudorabies virus in an aerosol was studied under different environmental conditions of temperature and relative humidity. Pseudorabies virus decayed logarithmically with mean half-lives of 17.4 (85% relative humidity, 22 C), 18.8 (25% relative humidity, 22 C), 27.3 (85% relative humidity, 4 C), 36.1 (55% relative humidity, 22 C), and 43.6 (55% relative humidity, 4 C) minutes. Virus survival was significantly improved in environments at 55% relative humidity, compared with those at 85% relative humidity (P = 0.017). Rates of survival were improved in environment at 4 C in comparison with those at 22 C. Results suggest that, under the best conditions of this study, the infectivity of pseudorabies virus in an aerosol decreases by 50% in less than 1 hour.

Epizootiologic aspects of viscerotropic velogenic Newcastle disease in six pet bird species.

Pet birds of 6 species were exposed to a psittacine isolate to viscerotropic velogenic Newcastle disease (VVND) virus to evaluate the impact of VVND in those species. Species examined were the budgerigar, yellow-headed Amazon parrot, canary, halfmoon conure, lesser hill mynah, and blackheaded nun. Five of the 6 species were highly susceptible to infection with VVND virus. Canaries were relatively refractory to infection with the virus. Contact birds of the same species developed infections almost as rapidly as did the birds directly exposed to nebulized VVND virus. Mortality was most marked for the conures. Less than half of the parrots exposed to nebulized virus died of VVND. Of the directly exposed budgerigars, mynahs, and nuns, 16% to 22% died during an observation period of postexposure days 0 through 28.

Experimental inoculation of raccoons (Procyon lotor) with rabies virus of skunk origin.

To determine raccoon (Procyon lotor) susceptibility and serum neutralizing antibody response to a skunk salivary gland rabies virus, raccoons were inoculated with a rabies virus isolated from a naturally-infected striped skunk (Mephitis mephitis). Raccoons were divided into four groups of three animals each. A dilution of the rabies virus suspension, 10(2.4), 10(3.4), or 10(4.8), mouse intracerebral lethal dose50 (MICLD50), was administered into the masseter muscles of each animal. Three negative control animals received only diluent. Saliva and sera were collected on post-inoculation days 35, 63 and 92 for virus isolation and determination of serum neutralizing antibody titer. All animals survived the 92 day observation period and none exhibited the behavioral changes classically associated with clinical rabies virus infections. Rabies virus was not detected in the saliva of any raccoon and two of the three animals receiving the highest inoculum developed serum neutralizing antibodies (SNA). On day 92, a challenge suspension of New York City/Georgia (NYC/GA) strain rabies virus in fox salivary glands (10(3.2) MICLD50) was administered to all 12 raccoons. All animals succumbed to rabies virus except the two animals that had earlier developed SNA. The results of this study provided evidence about the susceptibility of raccoons to a skunk rabies virus and demonstrated that exposed raccoons could survive for at least 92 days following exposure. Furthermore, animals developing SNA under such circumstances were capable of withstanding challenge with rabies virus that was fatal for seronegative raccoons.

Demonstration of rabies virus-specific antibody in the sera of free-ranging Iowa raccoons (Procyon lotor).

Between 1984 and 1988, a study was conducted to evaluate the frequency of rabies virus neutralizing antibodies in raccoons (Procyon lotor) in two counties in Iowa. Nine hundred eighty five raccoons were trapped and tagged in Guthrie and Cerro Gordo counties during the spring, summer and fall of each year. Sex, age and weight were recorded for each animal and a blood sample was collected. Serum samples were tested for the presence of serum neutralizing antibodies (SNA) by the rapid fluorescent focus inhibition test (RFFIT), mouse serum neutralization test (MSN), and an indirect fluorescent antibody (IFA) technique for detecting immunoglobulin G. Fifty-one raccoons (5%) were found to have SNA by the RFFIT. Thirty-six serum samples (24 with RFFIT antibody titer greater than 3.0, and 12 less than 3.0) were also tested by the MSN, with results correlating well with the RFFIT results (r = 0.86, P less than 0.01, Kappa = 0.93). In 35 raccoons with SNA by the RFFIT, six individuals had immunoglobulin G binding activity by the IFA test. These results provided serologic evidence of exposure of raccoons to rabies virus in an area free of enzootic raccoon rabies.