A growth study of Coxiella burnetii Nine Mile Phase I and Phase II in fibroblasts.

Coxiella burnetii, a slow-growing, gram-negative, obligate intracellular bacterium, is the causative agent of Q fever in humans. The avirulent Phase II C. burnetii Nine Mile strain can invade and establish persistent infections in a wide variety of laboratory cell lines, and is generally considered to be easier to grow in culture than the wild-type Phase I organism. Efforts to improve Phase I organism yield in the BHK-21 cell line demonstrated that high CO2 conditions and the use of Dulbecco's modified Eagle's medium (DMEM) with 4.5 g/l glucose supplementation resulted in higher organism yields. Phase II organisms grown in the same cell line and conditions showed lower growth rates. Analysis revealed that increased average numbers of C. burnetii Phase I organisms within fibroblasts was due to higher growth rates within the hosts rather than to increased uptake or to increased cell-to-cell spreading. Addition of the nucleoside cytidine to the growth medium stimulated growth of Phase II but not Phase I organisms.

Rabies epizootics among raccoons vary along a North-South gradient in the Eastern United States.

The characteristics of rabies epizootics among raccoons were investigated in 11 eastern states along a North-South gradient from New York to North Carolina. Epizootics were defined as discrete intervals of time of at least 5 months in duration, when reported cases of raccoon rabies from an individual county exceeded the median value of raccoon rabies cases reported by that county over the entire period rabies was present among raccoons in the county. Over the approximately 20-year study period, 35,000 cases of raccoon rabies were reported, and epizootics were detected from 251 (64.4%) of 390 counties. The median annual incidence was 0.14 epizootics per year. During the first defined epizootic in a county, the median total number of raccoons reported rabid was 47, with a median monthly incidence of rabies in raccoons of 3.1. The median lag time from the first report of a rabid raccoon in a county to the beginning of the first epizootic was 4 months. Significant differences in the annual incidence of epizootics and monthly incidence of rabid raccoons during epizootics were observed among different states. Although human population density and per capita health spending within counties were positively associated with increasing magnitude of epizootics, a significant difference in the characteristics of rabies epizootics in northern and southern states was apparent. We hypothesize that environmental conditions and perhaps human influence resulted in rabies epizootics in southern states that were smaller, less-frequent, and lacking in well-defined temporal structure compared with those in northern states.

Fort Chaffee revisited: the epidemiology of tick-borne rickettsial and ehrlichial diseases at a natural focus.

A retrospective cohort study was conducted among troops training at Fort Chaffee, Arkansas, from May through June 1997, to identify infections caused by tick-borne pathogens. Serum samples were tested by IFAs for antibodies to selected Rickettsia and Ehrlichia species and by an investigational EIA for spotted fever group Rickettsia lipopolysaccharide antigens. Of 1,067 guardsmen tested, 162 (15.2%) had antibodies to one or more pathogens. Of 93 guardsmen with paired serum samples, 33 seroconverted to Rickettsia rickettsii or spotted fever group rickettsiae (SFGR) and five to Ehrlichia species. Most (84.8%) of the personnel who seroconverted to SFGR were detected only by EIA, and seropositivity was significantly associated with an illness compatible with a tick-borne disease. In addition, 34 (27%) of 126 subjects with detectable antibody titers reported a compatible illness. The primary risk factor for confirmed or probable disease was finding > 10 ticks on the body. Doxycycline use and rolling up of long sleeves were protective against seropositivity. The risk of transmission of tick-borne pathogens at Fort Chaffee remains high, and use of the broadly reactive EIA suggests that previous investigations may have underestimated the risk for infection by SFGR. Measures to prevent tick bite and associated disease may require reevaluation.

Isolation compliance among university students during a mumps outbreak, Kansas 2006.

A large mumps outbreak occurred among students at a Kansas university in 2006. To reduce transmission, students with mumps were asked to isolate themselves. We describe isolation measures and student compliance with these measures. Questionnaires were administered to students suspected of having mumps. Of the 132 students instructed to stay isolated, 75% stayed isolated for the number of days recommended and were considered compliant. Case-students told to stay isolated for 1-4 days were more likely to be compliant [86% vs. 66%; adjusted odds ratio (aOR) 3.6, 95% CI 1.4-9.0] than those told to stay isolated for 5-9 days. Those who rated avoiding contact with others during isolation as very important were also more likely to be compliant (83% vs. 60%; aOR 3.6, 95% CI 1.5-8.4) than those who rated the importance lower. In a college setting, it may be difficult to achieve high compliance with guidelines recommending that persons stay isolated for much longer than 4 days.

Temporal dynamics of rabies in a wildlife host and the risk of cross-species transmission.

An epidemiological model was developed for rabies, linking the risk of disease in a secondary species (cats) to the temporal dynamics of disease in a wildlife reservoir (raccoons). Data were obtained from cats, raccoons, and skunks tested for rabies in the northeastern United States during 1992-2000. An epizootic algorithm defined a time-series of successive intervals of epizootic and inter-epizootic raccoon rabies. The odds of diagnosing a rabid cat during the first epizootic of raccoon rabies was 12 times greater than for the period prior to epizootic emergence. After the first raccoon epizootic, the risk for cat rabies remained elevated at levels six- to seven-fold above baseline. Increased monthly counts of rabid raccoons and skunks and decreasing human population density increased the probability of cat rabies in most models. Forecasting of the public health and veterinary burden of rabies and assessing the economics of control programmes, requires linking outcomes to dynamic, but predictable, changes in the temporal evolution of rabies epizootics.

Trends in infectious disease hospitalizations among American Indians and Alaska Natives.

OBJECTIVES: This study sought to describe trends in hospitalizations associated with infectious diseases among American Indians and Alaska Natives. METHODS: Infectious disease hospitalizations and rates among American Indians and Alaska Natives from 1980 through 1994 were examined via Indian Health Service hospital discharge data and compared with published trends for the general US population. RESULTS: Annual hospitalization rates for infectious diseases among American Indians and Alaska Natives decreased by 31.0% between 1980 and 1994. Infectious disease hospitalizations accounted for 16.3% of all hospitalizations in 1980 and 21.2% in 1994, an increase of 30.1%. In 1994, the age-adjusted infectious disease hospitalization rate for American Indians and Alaska Natives was 1863 per 100,000 population, approximately 21% greater than that for the general US population. CONCLUSIONS: Hospitalization trends for infectious diseases show that there has been improvement in the health status of American Indians and Alaska Natives but also indicate that this population has a higher infectious disease burden than the general US population.

Analysis of risk factors for fatal Rocky Mountain Spotted Fever: evidence for superiority of tetracyclines for therapy.

Epidemiologic and clinical characteristics of fatal and nonfatal cases of Rocky Mountain spotted fever (RMSF) were compared to identify risk factors for death caused by this disease. Confirmed and probable RMSF cases reported through US national surveillance for 1981-1998 were analyzed. Among 6388 RMSF patients, 213 died (annual case-fatality rate, 3.3%; range, 4.9% in 1982 to 1.1% in 1996). Use of tetracycline-class antibiotics for treatment of RMSF increased significantly in the 1990s, compared with use in the 1980s. Older patients, patients treated with chloramphenicol only, patients for whom tetracycline antibiotics were not the primary therapy, and patients for whom treatment was delayed > or =5 days after the onset of symptoms were at higher risk for death. Although the case-fatality rate was lower in the 1990s than in the 1980s, risk factors for fatal RMSF were similar. Despite the availability of effective antibiotics, RMSF-related deaths continue to occur because of delayed diagnosis and failure to use appropriate therapy.

Predicting the local dynamics of epizootic rabies among raccoons in the United States.

Mathematical models have been developed to explore the population dynamics of viral diseases among wildlife. However, assessing the predictions stemming from these models with wildlife databases adequate in size and temporal duration is uncommon. An epizootic of raccoon rabies that began in the mid-Atlantic region of the United States in the late 1970s has developed into one of the largest and most extensive in the history of wildlife rabies. We analyzed the dynamics of local epizootics at the county level by examining a database spanning more than 20 years and including 35,387 rabid raccoons. The size, number, and periodicity of rabies epizootics among raccoons were compared with predictions derived from a susceptible, exposed, infectious, and recovered model of raccoon rabies [Coyne, J., Smith, G. & McAllister, F. E. (1989) Am. J. Vet. Res. 50, 2148-2154]. After our methods for defining epizootics were applied to solutions of the model, the time series revealed recurrent epizootics in some counties, with a median first epizootic period of 48 months. Successive epizootics declined in size and the epizootic period progressively decreased. Our reanalysis of the model predicted the initial-epizootic period of 4-5 years, with a progressive dampening of epizootic size and progressive decrease in epizootic period. The best quantitative agreement between data and model assumed low levels of immunity (1-5%) within raccoon populations, suggesting that raccoons develop little or no rabies immune class. These results encourage the use of data obtained through wildlife surveillance in assessing and refining epidemic models for wildlife diseases.

Rapid evaluation of risk of white particulate matter in blood components by a statewide survey of transfusion reactions.

BACKGROUND: In January 2003, white particulate matter (WPM) was detected in blood components. Because the composition and cause of WPM was not understood at that time, there was uncertainty about whether WPM could endanger patient safety. To investigate possible adverse patient events associated with WPM, transfusion reaction rates were examined. STUDY DESIGN AND METHODS: A questionnaire was distributed to Georgia medical centers. Data collected included the number of components transfused and reported adverse reactions by component type from January 2002 through January 2003, and date, reaction type, and blood supplier for events in January 2003. RESULTS: Of 124 transfusion services contacted, 108 (87%) responded. During the survey period, there were 1213 reported transfusion reactions and 528,412 units transfused, or 2.3 reactions per 1000 units transfused; for RBCs, 2.4 (range, 1.8-3.1); plasma, 1.5 (range, 0.6-3.5); and PLTs, 3.4 (2.1-5.4) per 1000 units. Transfusion reaction rates by component for January 2003 did not differ significantly from the rate for January 2002 or for the calendar year. The 86 reported reactions that occurred in January 2003 were attributed to bacterial contamination (n = 2, 2.3%), other febrile nonhemolytic (n = 49, 57.0%), allergic (n = 14, 16.3%), and "other" reactions (n = 21, 24.4%); the proportions of reaction types did not differ significantly during the month. CONCLUSION: No overall changes in reported adverse reaction rates occurred over the survey period or in the proportion of reaction types during January 2003 when WPM was detected. Statewide surveillance of transfusion reactions could be useful to evaluate potential threats to blood safety.

Trends in intussusception-associated hospitalizations and deaths among US infants.

CONTEXT: The newly licensed tetravalent rhesus-human reassortant rotavirus vaccine has been withdrawn following reports of intussusception among vaccinated infants. OBJECTIVE: To describe the epidemiology of intussusception-associated hospitalizations and deaths among US infants. DESIGN: This retrospective cohort study examined hospital discharge data from the National Hospital Discharge Survey for 1988-1997, Indian Health Service (IHS) for 1980-1997, California for 1990-1997, Indiana for 1994-1998, Georgia for 1997-1998, and MarketScan for 1993-1996, and mortality data from the national multiple cause-of-death data for 1979-1997 and linked birth/infant death data for 1995-1997. PATIENTS: Infants (<1 year old) with an International Classification of Diseases, Ninth Revision, Clinical Modification code for intussusception (560.0) listed on their hospital discharge or mortality record, respectively. RESULTS: During 1994-1996, annual rates for intussusception-associated infant hospitalization varied among the data sets, being lowest for the IHS (18 per 100 000; 95% confidence interval [CI] = 9-35 per 100 000) and greatest for the National Hospital Discharge Survey (56 per 100 000; 95% CI = 33-79 per 100 000) data sets. Rates among IHS infants declined from 87 per 100 000 during 1980-1982 to 12 per 100 000 during 1995-1997 (relative risk =7.6, 95% CI = 3.2-18.2). Intussusception-associated hospitalizations were uncommon in the first 2 months of life, peaked from 5 to 7 months old, and showed no consistent seasonality. Intussusception-associated infant mortality rates declined from 6.4 per 1 000 000 live births during 1979-1981 to 2.3 per 1 000 000 live births during 1995-1997 (relative risk = 2.8, 95% CI = 1.8-4.3). Infants whose mothers were <20 years old, nonwhite, unmarried, and had an education level below grade 12 years were at an increased risk for intussusception-associated death. CONCLUSIONS: Intussusception-associated hospitalization rates varied among the data sets and decreased substantially over time in the IHS data. Although intussusception-associated infant deaths in the United States have declined substantially over the past 2 decades, some deaths seem to be related to reduced access to, or delays in seeking, health care and are potentially preventable.intussusception, hospitalizations, deaths, risk factors, infants.