Molecular epidemiology of norovirus gastroenteritis outbreaks in North Carolina, United States: 1995-2000.

Noroviruses (NoVs) are the most common cause of acute non-bacterial gastroenteritis outbreaks in the US. We investigated 16 gastroenteritis outbreaks in North Carolina (NC), from 1995 to 2000, to further characterize the epidemiology of NoV using RT-PCR on stool and ELISA on sera. NoV were identified in 14 outbreaks by RT-PCR. Sequence analyses of the amplicons indicated the outbreak strains belonged to the following clusters: five GII/4, three GI/3, one GI/4, one GII/2, one GII/5, one GII/7, and one GII/13 (prototype strain). We detected NoV in stool samples from one outbreak but could not determine its specific cluster within the GII genogroup based on polymerase sequence analysis. The five GII/4 strains were classified as the "95/96 US common strain" and occurred throughout the 5-year period. In contrast to national trends, the majority (86%) of NoV outbreaks identified in North Carolina were foodborne. Of the 12 food-related NoV outbreaks, we were able to document transmission by food handlers in two outbreaks. Person-to-person transmission from primary cases was suggested in three outbreaks. Our results indicate that NoVs are important agents of viral gastroenteritis outbreaks in NC.

Histamine poisoning associated with eating tuna burgers.

CONTEXT: Histamine poisoning occurs when persons ingest fish in which bacteria have converted histidine to histamine, a process that usually can be controlled by storage at low temperatures. From 1994 to 1997, North Carolina averaged 2 cases annually; however, from July 1998 to February 1999, a total of 22 cases of histamine fish poisoning were reported. OBJECTIVES: To examine the increase in histamine case reports, identify risk factors for poisoning, and develop recommendations for prevention. DESIGN AND SETTING: Case series evaluated in North Carolina from July 1998 to February 1999. SUBJECTS: Reported case-patients with 2 of the following symptoms within 2 hours of eating tuna: rash, facial flushing, vomiting, diarrhea, dyspnea, a tight feeling in the throat, headache, or a metallic or peppery taste in the mouth. RESULTS: Twenty cases occurred during 5 outbreaks, and there were 2 single occurrences. Of the 22 persons affected, 19 (86%) sought emergency medical care. All case-patients ate tuna: 18 ate tuna burgers, 2 ate salad containing tuna, and 2 ate filets. Tuna samples (available from 3 outbreaks) had histamine levels above the Food and Drug Administration regulatory level of 50 ppm (levels were between 213 and 3245 ppm). In 19 cases, the tuna used to prepare burgers or salads was frozen and thawed more than once before serving. Violations of recommended temperature controls were identified in 2 of the 5 restaurants, accounting for 14 (64%) cases. CONCLUSIONS: Tuna burgers, a relatively new menu item in restaurants, were associated with an increase in histamine poisoning cases in North Carolina. Tuna ground for burgers can be susceptible to both temperature fluctuations and bacterial contamination.

Transmission of Norwalk virus during a football game.

BACKGROUND: During a college football game in Florida, diarrhea and vomiting developed in many of the members of a North Carolina team. The next day, similar symptoms developed in some of the players on the opposing team. METHODS: We interviewed those who ate the five meals served to the North Carolina team before the game and some of the players on the opposing team who became ill. Patients with primary cases were members or staff of the team who had vomiting or diarrhea at least 10 hours after but no more than 50 hours after eating a box lunch served the day before the game. Patients with secondary cases had a later onset of symptoms or had symptoms without having eaten the box lunch. Stool samples were examined by electron microscopy and by a reverse-transcription-polymerase-chain-reaction (RT-PCR) assay. RESULTS: The two football teams shared no food or beverages and had no contact off the playing field. Of five meals served to the North Carolina team before the game, only the box lunch was associated with a significant risk of illness (relative risk of illness, 4.1; 95 percent confidence interval, 1.6 to 10.0). The rate of attack among those who ate the box lunch was 62 percent. There were 11 secondary cases among the members and staff of the North Carolina team and 11 such cases among the Florida players. All four stool samples obtained from North Carolina patients were positive for Norwalk-like virus on electron microscopy. All four samples as well as one of two stool samples from players on the Florida team were positive for a Norwalk-like virus of genogroup I on RT-PCR assay; the RT-PCR products had identical sequences. CONCLUSIONS: This investigation documents person-to-person transmission of Norwalk virus among players during a football game. Persons with acute gastroenteritis should be excluded from playing contact sports.

Coinfection with multiple tick-borne pathogens in a Walker Hound kennel in North Carolina.

Both dogs and humans can be coinfected with various Ehrlichia, Bartonella, Rickettsia, and Babesia species. We investigated a kennel of sick Walker Hounds and their owners in southeastern North Carolina for evidence of tick-borne infections and associated risk factors. A high degree of coinfection was documented in the dog population. Of the 27 dogs, 26 were seroreactive to an Ehrlichia sp., 16 to Babesia canis, and 25 to Bartonella vinsonii, and 22 seroconverted to Rickettsia rickettsii antigens. According to PCR results, 15 dogs were infected with Ehrlichia canis, 9 with Ehrlichia chaffeensis, 8 with Ehrlichia ewingii, 3 with Ehrlichia equi, 9 with Ehrlichia platys, 20 with a Rickettsia species, 16 with a Bartonella species, and 7 with B. canis. The detection of DNA from any Ehrlichia species was associated with clinical illness and with concurrent B. canis infection (by PCR). Both E. canis and an uncharacterized Rickettsia species appeared to result in chronic or recurrent infection. Death in the dog population was associated with living in a dirt lot rather than the concrete kennel. Of 23 people on whom serologic testing was conducted, eight were seroreactive to Bartonella henselae, one to E. chaffeensis, and one to R. rickettsii antigen; however, none had clinical or hematologic abnormalities consistent with illness caused by these organisms. We conclude that kennel dogs with heavy tick exposure can be infected at a high rate with multiple, potentially zoonotic, tick-borne pathogens. In addition, our findings further illustrate the utility of PCR for documenting coinfection with tick-transmitted pathogens.

A large outbreak of antibiotic-resistant shigellosis at a mass gathering.

In July 1987, a large outbreak of shigellosis occurred among attendees at a mass gathering in a national forest, the annual Rainbow Family Gathering. Sanitation in the campsite was poor, allowing widespread transmission of disease, probably by food, water, and person-to-person spread. The attack rate may have been greater than 50% among the estimated 12,700 attendees. The outbreak was caused by Shigella sonnei, resistant to ampicillin, tetracycline, and trimethoprim-sulfamethoxazole; the organism was of colicin type 9 and contained a 90-kilobase plasmid not found in non-outbreak-related strains. The dispersal of the group resulted in nationwide dissemination of the organism, and outbreaks in three states were linked to transmission from attendees at the Gathering. This outbreak demonstrates the potential for rapid dissemination of disease in such a setting and the necessity for careful planning of mass gatherings.

Risk factors for tornado injuries.

Tornadoes in North and South Carolina on 28 March 1984 caused 252 people to be injured seriously enough to require hospitalization and 59 to be killed. To evaluate risk factors, we gathered information on 238 (94%) of those hospitalized and 46 (78%) of those killed. Those hospitalized or deceased had statistically significantly more deep cuts, concussions, unconsciousness and broken bones than those with them at the time of the tornado who were not hospitalized or killed. People living in mobile homes were more likely to be hospitalized or die than people occupying conventional houses. Other risk factors for hospitalization or death included advanced age (60+ years), no physical protection (not having been covered with a blanket or other object), having been struck by broken window glass or other falling objects, home lifted off its foundation, collapsed ceiling or floor, or walls blown away. More awareness of the tornado risk before it strikes and better adherence to tornado protection guidelines could reduce injuries and deaths in the future.

Pertussis immunization in eight-month-old children in North Carolina.

Between 1984 and 1987 reported pertussis cases in North Carolina increased threefold. Pertussis immunization rates were examined for those years in three one-year cohorts drawn from a random selection of North Carolina birth records. The percentage of children immunized with three DTPs at eight months of age was 58.1, 58.6, and 56.7 for the three cohorts. Only 20.5 percent of 117 reported pertussis cases in children 9-36 months of age during the last 10 years were adequately immunized. The low pertussis immunization rate may have contributed to the recent increase in pertussis cases in North Carolina.

Risk factors for tornado injuries

Tornadoes in North and South Carolina on 28 March 1984 caused 252 people to be injured seriously enough to require hospotalization and 59 to be killed. To evaluate risk factors, we gathered information on 238 (94

) of those hospitalized and 46 (78

) of those killed. Those hospitalized or deceased had statistically significantly more deep cuts, concussions, unconsciousness and broken bones than those with them at the time of the tornado who were not hospitalized or killed. People living in mobile homes were more likely to be hospitalized or die than people occupyng conventional houses. Other risk factors for hospitalization or death included advanced age (60+ years), no physical protection (not having been covered with a blanket or other object), having been struck by broken window glass or other falling objects, home lifted offits foundation, collapsed ceiling or floor, or walls blown away. More awareness of the tornado risk before it strikes and better adherence to tornado protection guidelines could reduce injuries and deaths in the future (AU)

Antibodies to spotted fever-group rickettsiae in dogs in North Carolina.

A seroepidemiologic survey was conducted to determine the prevalence of antibodies reactive with 4 spotted fever-group (SFG) rickettsiae in sera of dogs from various geographic regions in North Carolina. Serum specimens were obtained from 600 dogs, and antibody titers were determined, using microimmunofluorescence. Data analysis (setting as the criterion for a positive result, a Rickettsia rickettsii titer greater than or equal to 1:64) overestimated the actual prevalence of canine exposure to this rickettsia. When data were analyzed by considering each dog's serologic response to all 4 rickettsial antigens simultaneously, the prevalence rate for exposure to R montana was 15%, to R rhipicephali was 11%, and to R rickettsii was 5%. A definitive exposure to R bellii was not observed, and the identification of the specific inciting rickettsia could not be established for 13% of the dogs, because of identical highest titers to 2 or more antigens. Our data indicate that canine exposure to R rhipicephali is prevalent in the eastern coastal region, whereas exposure to R montana takes place uniformly throughout the state. Rickettsia rickettsii exposure appears to be more prevalent in the central Piedmont region, but rarely is encountered in the western mountains. Regional seroprevalence for canine R rickettsii exposure approximates that for human exposure. Our findings support earlier suggestions that dogs may serve as environmental sentinels for establishing the geographic prevalence of foci of spotted fever.

Control of a non-foodborne outbreak of salmonellosis: day care in isolation.

We report an outbreak of Salmonella typhimurium in the infant room of a day care center. Time between onset dates, clustering of cases in the room, lack of a common food exposure, lack of illness among other children and staff, and lack of community-wide infection suggested person-to-person or continuing-common-source transmission. Successful preventive measures included instruction of personnel in proper handwashing and diaper-changing procedures and cohorting of infected and non-infected children. This is the second description of a non-foodborne outbreak of salmonellosis in a day care center, and the first involving S. typhimurium.

One-time screening to define the problem: Legionella exposure in an electric power company.

An electric utility screened 1,455 production employees for job exposure to Legionella pneumophila sources, illness history, and antibodies to L pneumophila serotypes I-IV. L pneumophila-associated illness outbreaks had occurred in a neighboring electric utility district; bacteria serocompatible with L pneumophila had been detected in all four plants participating in an environmental survey, and the company was concerned about the implications of these findings for their employees and the public living near power plants with large cooling towers. The survey revealed a prevalence of antibodies in employees consistent with general population surveys. Within the employee group, antibody titer was not associated with either reports of recent illness or work exposure to potential L pneumophila sources. Inability to detect a relationship between exposure to potential L pneumophila sources and specific antibody results was used to define L pneumophila as a historic nonproblem for this company and to rationally advise against the need for an ongoing screening program.

The prevalence of antibodies to Rickettsia rickettsii in an area endemic for Rocky Mountain spotted fever.

A study of Rickettsia rickettsii was conducted in Rowan, Cabarrus, and Granville counties, North Carolina in an attempt to define the prevalence of endemic infection in this area. Serum samples were obtained from 1,976 healthy persons and tested by indirect hemagglutination for detectable antibodies to R. rickettsii. Of this group, 568 (28.7%) had detectable antibody (greater than or equal to 1:8), 80 (4%) had titers greater than or equal to 1:64, and 1,408 (70%) had no detectable antibody (less than or equal 1:8). Indirect immunofluorescence testing for antibody was also performed for 315 (15%) of the serum samples, of which 301 (95%) had undetectable titers and 14 (5%) had detectable titers ranging from 1:8 to greater than or equal to 1:64. Serological reactivity by indirect hemagglutination was detected in persons in the absence of known Rocky Mountain spotted fever. The study failed to show a good correlation of either the height of the geometric mean titer or percentage of seropositive persons with the previously determined age-related rates of acquisition of the disease. These data suggest that the antibodies measured may not be specific for R. rickettsii or that the antibody levels wane with time or both. It is probable that unrecognized infection occurs, but the true incidence or prevalence cannot be determined by available serological tests.

Epidemiology of Rocky Mountain spotted fever as determined by active surveillance.

Prospective, active surveillance for Rocky Mountain Spotted fever (RMSF) was undertaken in two North Carolina counties for the years 1979-1981. Appropriate age, sex, and geographically matched controls were compared with the serologically confirmed cases of disease. Patients who were suspected of having infection, but were shown not to have RMSF, were also compared with the serologically proven cases. Ninety-eight cases were identified, and three of these patients died. The mean annual incidence of RMSF in these two counties was 14.59 cases/100,000 population. Identified cases occurred between the months of March and September. The overall mean annual incidence for men was 19.65/100,000 and for women 10.3/100,000. The study suggests that persons contracting RMSF are exposed to the vectors at their residences, which tend to be detached dwellings in woody, brushy areas. Children are more likely than adults both to be seen by physicians early in the illness and to be checked for ticks. Eighty-four percent of patients with serologically confirmed cases developed a rash. The epidemiology of RMSF in these two endemic counties is described.

Detection of Rickettsia rickettsii antibodies in human sera by crossed immunoelectrophoresis.

To identify Rickettsia rickettsii antigens of immunological importance, we examined sera from patients with serologically confirmed cases of Rocky Mountain spotted fever by crossed immunoelectrophoresis for antibodies to antigens extracted from the R strain of R. rickettsii with the detergent Triton X-100. Sixteen antigens were identified in the detergent extract by crossed immunoelectrophoresis with a hyperimmune rabbit serum raised against whole rickettsiae. When the rabbit antiserum was placed in the reference gel and patient sera were placed in the intermediate gel, antibodies to one or more antigens were detected in 61 of 71 North Carolina sera, all of 7 Oklahoma sera, and 9 of 10 Montana sera obtained from 1 day to 40 years after onset of Rocky Mountain spotted fever. Antibodies to antigens 1 and 16 were found as early as 1 day after onset of illness, and antibody to 16 was found in 20 of 29 sera obtained within the first 7 days of illness. Antibodies to antigens 2 and 3 generally did not appear until the third week of illness but were found in six of seven serum samples collected 4 to 40 years after onset of Rocky Mountain spotted fever. Antibodies to R. rickettsii antigens 1, 7, 8, and 16 were found in sera from patients with illnesses caused by other etiological agents. Four of the Oklahoma and Montana sera from Rocky Mountain spotted fever patients, but none of the North Carolina sera, had antibodies to antigen 12. Sera containing antibodies against antigens 3 and 14 prevented death of mice challenged with two 50% lethal doses of R. rickettsii.

Aseptic meningitis among members of a high school football team. An outbreak associated with echovirus 16 infection.

During the period Sept 1 through Oct 1, 1978, an outbreak of enteroviral illness affected 43 (70%) of the 61 members of a high school football team. Thirty-three (54%) had symptoms of aseptic meningitis, a diagnosis confirmed for each of seven players hospitalized. Echovirus 16 was recovered from a throat swab of one hospitalized player and from the CSF of another. Enteroviruses isolated from stool specimens taken after the illness from other ill players and from stool specimens of non-ill team members were also identified as echovirus 16. A survey among students not on the team showed an attack rate for enteroviral-like illness that was half that experienced by team members during the same period. Symptoms reported by nonteam members were less severe. Only 10% had an aseptic meningitis-like syndrome, and none were hospitalized. Membership on the school football team was associated with an increased attack rate of illness and a greater risk for aseptic meningitis developing.

Epidemic typhus in the United States associated with flying squirrels.

Between July 1977 and January 1980, seven cases of sporadic, nonepidemic "epidemic" typhus (Rickettsia prowazekii) were discovered in Virginia, West Virginia, and North Carolina. The reservoir seemed to be the southern flying squirrel (Glaucomys volans), an animal indigenous to the eastern United States; however, the vector or mode of acquisition was not evident. Diagnosis was established principally through complement fixation, indirect immunofluorescence, and toxin neutralization tests. Patients' ages were 11 to 81 years. Most were white women. Six had abrupt onset of illness. Headaches, fever, myalgias, and exanthems were among the presenting complaints. The disease seemed milder than classic louse-born epidemic typhus, but in some instances, it was life-threatening. All patients responded to tetracycline or chloramphenicol. This entity probably is more common than reported, is difficult to recognize, and is produced by an organism seemingly identical to that producing louse-born epidemic typhus.

Detection of Rocky Mountain spotted fever antibodies by a latex agglutination test.

A latex test for immunodiagnosis of Rocky Mountain spotted fever, using erythrocyte-sensitizing substance from Rickettsia rickettsii adsorbed to latex particles, has been developed. The test was evaluated with a total of 123 single and 118 paired human sera submitted for Rocky Mount spotted fever testing. This test is simple, sensitive, and specific. Its efficiency, relative to the reference microimmunofluorescence test, was 95.1% for single sera and approached 100% for paired sera.