Epidemiology, production losses, and control measures associated with an outbreak of avian influenza subtype H7N2 in Pennsylvania (1996-98).

An outbreak of H7N2 low-pathogenicity (LP) avian influenza (AI) occurred in a two-county area in Pennsylvania from December of 1996 through April of 1998. The outbreak resulted in infection of 2,623,116 commercial birds on 25 premises encompassing 47 flocks. Twenty-one (one premise with infection twice) of the twenty-five infected premises housed egg-laying chickens and one premise each had turkeys, layer pullets, quail, and a mixed backyard dealer flock. Despite dose proximity of infected flocks to commercial broiler flocks, no infected broilers were identified. Experimentally, when market age broilers were placed on an influenza-infected premise they seroconverted and developed oviduct lesions. The outbreak was believed to have originated from two separate introductions into commercial layer flocks from premises and by individuals dealing in sales of live fowl in the metropolitan New York and New Jersey live-bird markets. Source flocks for these markets are primarily in the northeast and mid-Atlantic areas, including Pennsylvania. Mixed fowl sold include ducks, geese, guinea hens, quail, chukar partridges, and a variety of chickens grown on perhaps hundreds of small farms. Infections with the H7N2 AI virus were associated with variable morbidity and temporary decreases in egg production ranging from 1.6% to 29.1% in commercial egg-laying chickens. Egg production losses averaged 4.0 weeks duration. Mortality ranged from 1.5 to 18.3 times normal (mean of 4.3 times normal). Duration of mortality ranged from 2 to 13 weeks (average of 3.9 weeks) in flocks not depopulated. Lesions observed were primarily oviducts filled with a mucous and white gelatinous exudates and atypical egg yolk peritonitis. Quarantine of premises and complete depopulation were the early measures employed in control of this outbreak. Epidemiological studies suggested that depopulation furthered the spread of influenza to nearby flocks. Thereafter, later control measures included quarantine, strict biosecurity, and controlled marketing of products.

Spatial and temporal epidemiology of pseudorabies virus infection.

OBJECTIVE: To examine the pattern of pseudorabies virus (PRV) infection in Pennsylvania and identify the area factors associated with herd quarantine status. SAMPLE POPULATION: 123 PRV-quarantined commercial swine herds identified between 1986 and 1993 were selected as cases, and 162 uninfected herds were selected as controls. PROCEDURE: Herd location, demographics, and temporal vaccination and quarantine data for a case-control study were obtained from producer questionnaires and state records, using a database of swine herds from 2 Pennsylvania counties. Any herd that was on quarantine as of Jan 1, 1991, or quarantined subsequent to this date, was defined as a case. A herd was defined as a control if it had never been quarantined for PRV. Controls were group matched to cases by year. Study herds were centered in a circle, or buffer zone, with a 1.61-km (1-mile), 3.22-km (2-mile), or 6.44-km (4-mile) radius, and densities of operation types, quarantined herds, nonquarantined herds, and vaccinated herds in the buffer zone were compared. The analytical outcome was the probability of a herd being quarantined, conditional on the buffer zone density of herds quarantined, herds not quarantined, and herds in which a PRV vaccine was used. These density variables were categorized into high, medium, and low, or just high and low categories. Confounding by year was assessed in the analysis. Analysis was performed, using unconditional logistic regression. RESULTS: Decreased density of PRV-quarantined herds in the study region was associated with reduced risk of a herd becoming quarantined, whereas increased density of nonquarantined, presumably uninfected herds was associated with decreased probability of a herd becoming quarantined. Decreased density of vaccinated herds was associated with increased probability of a herd becoming quarantined. In addition, being a farrow-to-finish study herd was associated with increased probability of becoming quarantined, compared with being a feeder pig producer study herd. CONCLUSIONS: Associations with quarantine status and area densities of vaccinated, nonquarantined, and quarantined herds indicate the importance of area spread in PRV control. These effects are seen most strongly at a 3.22-km (2-mile) radius, but also are seen at a 6.44-km (4-mile) radius.

Toxicology of selected pesticides, drugs, and chemicals. Boric acid.

With the advent of boric acid insecticides, accidental ingestion of the compound can be encountered in animals. Toxic levels of boric acid most commonly cause vomiting, depression, and, occasionally, diarrhea. Boric acid is, however, cytotoxic to all cells. If a sufficiently high level is ingested, seizures, renal tubular nephrosis, and, rarely, hepatotoxicity may be noted. Gastrointestinal evaluation and supportive care are usually of primary therapeutic importance, although in severe cases, exchange transfusion and/or peritoneal dialysis may be required to decrease blood boron concentrations.

Toxicology of household cleaning products and disinfectants.

Hundreds of different household cleaning products are available in homes, presenting potential hazards to pets. These products are complex mixtures of chemicals that vary widely in their toxic potential. Prevention of toxicoses in companion animals follows the same guidelines as those recommended for children: Keep cleaning products out of the reach of pets, do not leave open containers or solutions of cleaning products unattended where animals may get into them, make sure containers of cleaning products are tightly sealed and properly labeled, and dispose of any cleaning solutions promptly after use. If a companion animal has ingested or spilled a cleaning product or disinfectant on itself, it is very important to assess the potential hazard to the animal promptly. Many products contain warnings regarding the corrosive or irritation potential of the product and instructions on the label for preliminary action in the case of accidental oral, dermal, or ocular exposures in humans. These instructions can generally be followed initially until further information on the product can be obtained, although the recommendations on some product labels may be outdated. In general, the clinical management for toxicoses caused by cleaning products and disinfectants involves the prevention of further contact with the concentrated product through either dilution or bathing; emergency stabilization of the patient if clinical signs are present; instituting specific therapies, if available; and use of general supportive care.