Mumps outbreak at a summer camp--New York, 2005

On July 26, 2005, the Sullivan County Health Department (SCHD) and the New York State Department of Health (NYSDOH) were notified of a cluster of cases of parotitis among campers and staff members at a summer camp. An investigation conducted by NYSDOH identified 31 cases of mumps, likely introduced by a camp counselor who had traveled from the United Kingdom (UK) and had not been vaccinated for mumps. This report summarizes the results of the subsequent investigation by NYSDOH, which determined that, even in a population with 96% vaccination coverage, as was the case with participants in the summer camp, a mumps outbreak can result from exposure to virus imported from a country with an ongoing mumps epidemic.     

Cryptosporidiosis outbreak in a recreational swimming pool in Minnesota

On May 6, 1998, the Olmsted County Public Health Department initiated an investigation into an outbreak of diarrheal illness that had occurred among people who swam frequently at a local swimming pool. Interviews of swimmers and microbiological testing of stool samples and swimming pool filter material were conducted to determine the source of the outbreak. Twenty-six of 206 swimmers interviewed had illnesses that met the case definition. The most common symptoms were diarrhea (100 percent), abdominal cramps (81 percent), and nausea (77 percent). The median duration of symptoms was nine days. Four cases of cryptosporidiosis were confirmed by stool analysis. The outbreak was found to be associated with swimming at the pool. Public awareness-including an understanding that recreational water facilities should be avoided during diarrheal illness-and proper pool hygiene are vital in preventing cryptosporidiosis outbreaks. Health care providers also must consider testing specifically for cryptosporidiosis when a patient presents with persistent diarrhea.     

Cryptosporidiosis in Great Yarmouth--the investigation of an outbreak

A community outbreak of 36 cases of Cryptosporidium infection which occurred during Spring 1986 in Great Yarmouth and Waveney is described. A period prevalence study suggested that there was a more widespread outbreak of diarrhoeal illness in the locality although only 3/68 stool samples obtained at a median time interval of 38 days from the onset of symptoms contained Cryptosporidium oocysts. The distribution of cases of cryptosporidiosis in time and place suggested person to person spread rather than a common vehicle. A retrospective matched case-control study provided no evidence of water borne spread.     

Epidemiology of a tuberculosis outbreak in a South Carolina junior high school

A 13-year-old, female, seventh-grade student (the index patient) was found to have smear-positive, cavitary, pulmonary tuberculosis. Epidemiologic and contact investigation, involving skin testing over 900 people, revealed a 40 per cent tuberculin reactor rate for persons in the junior high school she attended compared to a 2 per cent rate for control schools. Repeat skin testing of initial non-reactors identified an additional 3 per cent of infected school children. School teachers showed a seven-fold increase in the prevalence of positive skin-test reactions following the outbreak. Tuberculin-reactor rates for seventh graders were substantially higher than for eighth graders. The more classes shared with the index patient, the higher the probability of being a reactor. Among students who shared no classes with the index patient, the highest rates of tuberculin reactions were found for those who had entered a classroom immediately after the index patient had left it. Evidence of transmission on the school bus and in the church choir was also suggested. Six secondary cases (three pulmonary) resulted from the outbreak. Identical phage types from the index and secondary patients suggest who had left school during the term proved useful in determining when transmission began. The index case was found to be a missed contact of a previously identified case of tuberculosis. Since household contacts are at high risk for developing active disease, there is a need for meticulous and complete investigation and preventive therapy for all such persons, especially children.     

Hospital-associated measles outbreak - Pennsylvania, March-April 2009

Although endemic measles transmission has been interrupted in the United States, importations of this highly infectious virus continue. On March 28, 2009, a physician notified the Pennsylvania Department of Health (PADOH) of a measles case involving an unvaccinated child. Within 5 days, four additional cases were reported to PADOH and the Allegheny County Health Department. All five infected persons had been in the same hospital emergency department (ED) on March 10; one of them was a physician who worked in the ED. To find the source patient, PADOH reviewed electronic records of patients evaluated in the ED on March 10 for fever and rash. This identified a child who arrived recently from India, was treated for viral exanthema, and discharged. On April 3, PADOH obtained serum from this child and confirmed a diagnosis of measles. After an extensive regional search and investigation of the six patients' 4,000 contacts, no additional cases were identified. The hospital reviewed employee health records to identify any exposed personnel who did not have serologic evidence of measles immunity. Among 168 potentially exposed employees, 72 (43%) had no documented measles immunity, thus requiring serologic testing and subsequent vaccination if they lacked serologic evidence of immunity. This outbreak highlights the potential for measles transmission in health-care settings. To decrease transmission, clinicians should know the signs and symptoms of measles, request travel histories of patients suspected of any infectious disease, and isolate potentially infectious patients. Hospital employees should have documented immunity to measles, and employees without evidence of measles immunity should be offered vaccination in accordance with Advisory Committee on Immunization Practices (ACIP) and Hospital Infection Control Practices Advisory Committee (HICPAC) recommendations.     

Cryptosporidiosis in children during a massive waterborne outbreak in Milwaukee,Wisconsin: clinical,laboratory and epidemiologic findings.

During the spring of 1993 an estimated 403000 residents of the greater Milwaukee, Wisconsin area experienced gastrointestinal illness due to infection with the parasite Cryptosporidium parvum following contamination of the city''s water supply. To define the clinical, laboratory and epidemiologic features of outbreak-associated cryptosporidiosis in children, medical and laboratory records for all children submitting stool samples to the microbiology laboratory of the Children''s Hospital of Wisconsin between 7 April and 13 May 1993 were reviewed retrospectively. Interviews with parents were also conducted to obtain additional clinical history. Cryptosporidium, as the sole pathogen, was identified in stools from 49 (23%) of the 209 children enrolled in the study. Children with laboratory-confirmed cryptosporidiosis were more likely to live in areas of Milwaukee supplied with contaminated water (RR = 1.92, CI = 1.19-3.09), to be tested later in their illness (P < 0.05), to have submitted more than one stool specimen (P = 0.01), to have an underlying disease that altered their immune status (RR = 2.78, CI = 1.60-4.84), and to be older than 1 year of age (RR = 2.02, CI = 1.13-3.60). Clinical illness in these patients was more prolonged and associated with weight loss and abdominal cramps compared with Cryptosporidium-negative children. In the context of this massive waterborne outbreak relatively few children had documented infection with Cryptosporidium. If many children who tested negative for the parasite were truly infected, as the epidemiologic data suggest, existing laboratory tests for Cryptosporidium were insensitive, particularly early in the course of illness.     

Waterborne outbreak of gastroenteritis in a religious summer camp in Norway, 2002

In July 2002 an outbreak of acute gastroenteritis occurred in a camp facility in western Norway during a 10-day seminar, with around 300 guests staying overnight and several day-time visitors. Environmental and epidemiological investigations were conducted to identify and eliminate the source of the outbreak, prevent further transmission and describe the impact of the outbreak. Of 205 respondents, 134 reported illness (attack rate, 65%). Multivariate analysis showed drinking water and taking showers at the camp-site to be significant risk factors. Secondary person-to-person spread among visitors or outside of the camp was found. Norovirus was identified in 8 out of the 10 stool samples analysed. Indicators of faecal contamination were found in samples from the private untreated water supply, but norovirus could not be identified. This outbreak investigation illustrates the importance of norovirus as a cause of waterborne illness and the additional exacerbation through person-to-person transmission in closed settings. Since aerosol transmission through showering contributed to the spread, intensified hygienic procedures such as isolation of cases and boiling of water may not be sufficient to terminate outbreaks with norovirus.     

Cryptosporidiosis outbreak in a Nassau County, Florida, return travel group from Ireland, May 24, 2006-June 4, 2006

The Nassau County Health Department (NCHD) in Florida investigated an outbreak of gastrointestinal (GI) illness in a returning choral group who toured Ireland from May 24 to June 4, 2006. The travel group, consisting predominantly of retirees, had performed at several churches and at a dinner theater in Ireland. The NCHD administered a telephone questionnaire to 40 of the 41 group members to examine possible water exposures; common meals; and food, travel, and clinical histories. The results of the questionnaire showed that 29 people met the case definition for the outbreak. Five stool samples from travel group members tested positive for Cryptosporidium parvum, a species that is animal in origin and often spread through an environmental contamination with animal feces. All five positive samples were subtyped 11aA16G1R1b, a strain that scientists at the Centers for Disease Control and Prevention (CDC) Division of Parasitic Diseases detected twice in 2006 in other human specimens from Northern Ireland.     

Dengue outbreak in Key West, Florida, USA, 2009

After 3 dengue cases were acquired in Key West, Florida, we conducted a serosurvey to determine the scope of the outbreak. Thirteen residents showed recent infection (infection rate 5%; 90% CI 2%-8%), demonstrating the reemergence of dengue in Florida. Increased awareness of dengue among health care providers is needed.     

Drug-susceptible tuberculosis outbreak in a state correctional facility housing HIV-infected inmates--South Carolina, 1999-2000

During 1999-2000, South Carolina's Department of Corrections (SCDC), Department of Health and Environmental Control (DHEC), and CDC investigated an outbreak of drug-susceptible tuberculosis (TB) that occurred in a state correctional facility housing human immunodeficiency virus (HIV)-infected inmates. All culture-confirmed case-patients have been linked by IS6110-based DNA fingerprinting of Mycobacterium tuberculosis isolates. This report describes the outbreak investigation and illustrates the need for increased vigilance for TB in settings in which HIV-infected persons congregate.     

Investigation of a ricin-containing envelope at a postal facility--South Carolina, 2003

On October 15, 2003, an envelope with a threatening note and a sealed container was processed at a mail processing and distribution facility in Greenville, South Carolina. The note threatened to poison water supplies if demands were not met. The envelope was isolated from workers and other mail and removed from the facility, and an investigation was begun. On October 21, laboratory testing at CDC confirmed that ricin was present in the container. To assess the human health effects related to possible ricin exposure, the South Carolina Department of Health and Environmental Control (SCDHEC) and CDC interviewed all workers at the postal facility and initiated statewide surveillance for illness consistent with ricin exposure during October 15-29. On October 22, the facility was closed for a detailed epidemiologic and environmental investigation. This report summarizes the results of the investigation, which found no evidence of environmental contamination and no cases of ricin-associated illness. Clinicians and public health officials should be vigilant for illnesses suggestive of ricin exposure.     

Presumptive summer influenza A: an outbreak on a trans-Tasman cruise

A number of recent reports from the Northern Hemisphere have drawn attention to the occurrence of summer outbreaks (May to August) of influenza A among cruise ship passengers and their contacts. In cases amongst passengers returning to Canada from Alaska, exposure appears to have occurred during the land-based Alaskan tour with illness developing during the subsequent cruise. A late summer outbreak of influenza A among passengers and crew on the return leg of a 14-day Sydney-New Zealand-Sydney cruise is reported in this article.     

First reported foodborne outbreak associated with microsporidia, Sweden, October 2009

Microsporidia are spore-forming intracellular parasites that infrequently cause disease in immunocompetent persons. This study describes the first report of a foodborne microsporidiosis outbreak which affected persons visiting a hotel in Sweden. Enterocytozoon bieneusi was identified in stool samples from 7/11 case-patients, all six sequenced samples were genotype C. To confirm that this was not a chance finding, 19 stool samples submitted by healthy persons from a comparable group who did not visit the hotel on that day were tested; all were negative for microsporidia. A retrospective cohort study identified 135 case-patients (attack rate 30%). The median incubation period was 9 days. Consumption of cheese sandwiches [relative risk (RR) 4·1, 95% confidence interval (CI) 1·4-12·2] and salad (RR 2·1, 95% CI 1·1-4) were associated with illness. Both items contained pre-washed, ready-to-eat cucumber slices. Microsporidia may be an under-reported cause of gastrointestinal outbreaks; we recommend that microsporidia be explored as potential causative agents in food- and waterborne outbreaks, especially when no other organisms are identified.     

Salmonellosis outbreak traced to playground sand, Australia, 2007-2009

A community outbreak of gastroenteritis in Australia during 2007-2009 was caused by ingestion of playground sand contaminated with Salmonella enterica Paratyphi B, variant Java. The bacterium was also isolated from local wildlife. Findings support consideration of nonfood sources during salmonellosis outbreak investigations and indicate transmission through the animal-human interface.     

Household responses to school closure resulting from outbreak of influenza B, North Carolina

School closure is a proposed strategy for reducing influenza transmission during a pandemic. Few studies have assessed how families respond to closures, or whether other interactions during closure could reduce this strategy's effect. Questionnaires were administered to 220 households (438 adults and 355 children) with school-age children in a North Carolina county during an influenza B virus outbreak that resulted in school closure. Closure was considered appropriate by 201 (91%) households. No adults missed work to solely provide childcare, and only 22 (10%) households required special childcare arrangements; 2 households incurred additional costs. Eighty-nine percent of children visited at least 1 public location during the closure despite county recommendations to avoid large gatherings. Although behavior and attitudes might differ during a pandemic, these results suggest short-term closure did not cause substantial hardship for parents. Pandemic planning guidance should address the potential for transmission in public areas during school closure.     

Rickettsia parkeri in Amblyomma maculatum ticks, North Carolina, USA, 2009-2010

We detected Rickettsia parkeri in 20%-33% of Amblyomma maculatum ticks sampled in North Carolina. Results highlight the high frequencies of R. parkeri-infected ticks in the state with the highest annual incidence of Rocky Mountain spotted fever. Epidemiologic studies are needed to definitively link R. parkeri to cases of spotted fever rickettsiosis.