Growth kinetics of the Lyme disease spirochete (Borrelia burgdorferi) in vector ticks (Ixodes dammini).

Lyme disease spirochetes (Borrelia burgdorferi) multiplied rapidly in larval Ixodes dammini, reaching a mean density of 2,735 spirochetes/tick on day 15 post-repletion. A 5-fold drop in spirochete levels occurred during the subsequent premolting period. Recently molted nymphs contained a mean of less than 300 spirochetes/tick. Following nymphal repletion, spirochete multiplication renewed, reaching a mean abundance of 61,275 spirochetes/nymph on day 75 post-repletion. A 10-fold drop in spirochete abundance occurred again when ticks molted to the adult stage. Tick-derived spirochetes proved to be infectious when greater than 10(4) spirochetes were inoculated ip into hamsters (4 of 4 animals infected). Inocula of 10(3-4) spirochetes were not always infectious (8 of 23 animals infected), and inocula of less than 10(3) spirochetes were insufficient for establishing infection (0 of 8 animals infected).

Ear punch biopsy method for detection and isolation of Borrelia burgdorferi from rodents.

An ear punch biopsy method for the detection and isolation of Borrelia burgdorferi from rodents was developed. The ear punch biopsy proved to be extremely sensitive, detecting spirochetes in 100% (11 of 11) of laboratory hamsters infected by tick bite and 95.8% (23 of 24) of hamsters infected by intraperitoneal inoculation. When cultured at 4 to 6 weeks postinfection, 92 to 100% of the ear punches taken from individual hamsters yielded viable spirochetes. B. burgdorferi was detected in sequential cultures from animals as early as 4 days postinfection and as late as 20 weeks postinfection. A total of 86% (6 of 7) of field-collected white-footed mice (Peromyscus leucopus) which were positive for B. burgdorferi as determined by xenodiagnosis were also positive by the ear punch method. The ear punch biopsy method allows individual rodents to be sampled for B. burgdorferi serially over a long period and thus should prove useful for both field and laboratory experiments.

Duration of tick attachment and Borrelia burgdorferi transmission.

Nymphal Ixodes dammini transmitted Borrelia burgdorferi to 1 of 14 rodents exposed for 24 h, 5 of 14 rodents exposed for 48 h, and 13 of 14 rodents exposed for greater than or equal to 72 h. Prompt removal of attached ticks is a prudent public health measure, especially in regions where Lyme disease is endemic.

Simultaneous transmission of Borrelia burgdorferi and Babesia microti by individual nymphal Ixodes dammini ticks.

Nymphal Ixodes dammini ticks, selected from a group of ticks in which 22 of 31 (71%) contained dual Borrelia burgdorferi and Babesia microti infections, simultaneously transmitted B. burgdorferi and B. microti to 4 of 7 (57%) hamsters exposed to individual ticks.

Infant mortality review as a vehicle for quality improvement in a local health department.

BACKGROUND: Many communities across the United States have established fetal and infant mortality review (FIMR) programs as a way of gaining insight into the causes of such deaths and of devising and implementing ways to improve the health of pregnant women and their infants. IMR PROCESS: The IMR process in the Jefferson County Department of Health in Birmingham, Alabama, evolved in a somewhat different fashion than that in other communities. A technical review team reviews all the infant deaths in the county, with particular attention to each woman's pregnancy history. A community review team reviews composite cases that illustrate some particular problem that might lead to infant mortality, such as teenage pregnancy or short intervals between pregnancies. This team provides insights into cultural patterns and a community perspective on the problems. Recommendations from the two teams are acted on by the health department, with the assistance of other agencies as needed. IMPACT OF THE IMR PROCESS: The IMR process has been used to increase community agency participation in health department activities, improve health department procedures, increase health department staff acceptance of a new and controversial program (Healthy Start), and offer services to women who need them. CONCLUSIONS: IMR has become a mechanism for CQI in the health department, embodying many of the principles of CQI, including the use of teams, focus on a team mission, and examination of processes, not individuals. The program offers a model of how to reduce rates of fetal and infant mortality.

Virulence factors of Bordetella bronchiseptica associated with the production of infectious atrophic rhinitis and pneumonia in experimentally infected neonatal swine.

Four strains of Bordetella bronchiseptica (CSU-P-1, 64-C-0406, 1120-A-83-013, and B205BT) with defined virulence for neonatal swine were examined, and an attempt was made to correlate the presence of certain in vitro phenotypic characteristics with the ability of a particular B. bronchiseptica strain to produce turbinate and lung lesions in piglets. All of the strains except CSU-P-1 colonized the nasal passages of the pigs heavily, and strains 1120-A-83-013 and B205BT produced moderate to severe nasal and lung lesions in experimentally infected piglets. All of the strains attached equally well to porcine tracheal ring explant cultures, and all of the strains except CSU-P-1 produced smooth, hemolytic colonies on Bordet-Gengou medium, agglutinated porcine erythrocytes, and possessed adenylate cyclase activity. Strains 1120-A-83-013 and B205BT produced considerably higher levels of dermonecrotic toxin activity than did strains CSU-P-1 and 64-C-0406. These results indicate that production of nasal and lung lesions in neonatal piglets by the B. bronchiseptica strains tested can be directly correlated with their level of dermonecrotic toxin production.