Communitywide cryptosporidiosis outbreak--Utah, 2007

Cryptosporidiosis is a nationally notifiable gastrointestinal illness caused by chlorine-resistant protozoa of the genus Cryptosporidium. Fecal-oral transmission of Cryptosporidium occurs via ingestion of contaminated recreational water, drinking water, or food, or via contact with infected persons or animals (e.g., cattle). Incidence peaks in late summer and coincides with the summer swimming season. The number of nonoutbreak cryptosporidiosis cases reported nationally increased from 3,411 cases in 2004 to nearly 8,300 in 2007 (CDC, unpublished data, 2008). This substantial increase (143%) mirrors the increase in the number of nationally reported cryptosporidiosis outbreaks associated with treated recreational water venues (e.g., pools, water parks, and interactive fountains): seven reported treated recreational water-associated outbreaks in 2004, 19 in 2006, and, as of September 5, 2008, provisional reports of 26 in 2007 (CDC, unpublished data, 2008). This report describes a communitywide cryptosporidiosis outbreak in Utah that likely was associated initially with treated recreational water venues and subsequently with person-to-person transmission. Cryptosporidium's ability to cause communitywide outbreaks, which is attributable to factors such as its chlorine resistance, underscores the need for more rapid implementation of control measures once an increase in case reporting is noted rather than waiting for an outbreak investigation to implicate a specific source of transmission. Such a response should include 1) pre-outbreak planning and preparation, 2) pre-outbreak adoption of a disease action threshold (e.g., a twofold to threefold increase in cases over baseline), and 3) rapid mobilization of community partners to implement control measures once the threshold is exceeded.     

Retrospective cohort study of an outbreak of cryptosporidiosis caused by a rare Cryptosporidium parvum subgenotype

The occurrence of a gastrointestinal illness among a class of 96 undergraduate veterinary students in New Zealand prompted laboratory and questionnaire-based investigations. Cryptosporidium parvum was the only enteropathogen identified in 4/7 faecal specimens analysed. The C. parvum isolates carried a rare IIa GP60 allele, indicating a point-source outbreak. The infection source could not be microbiologically traced, but the investigation suggested contact with calves during a practical class as the most likely exposure. A total of 25/80 respondents to a questionnaire were defined as cases using a clinical case definition (31% attack rate). The inferred median incubation period was 5 days (range 0-11 days), and the median illness duration was 5-6 days (range 2-23 days), corroborating previous observations in experimental cryptosporidiosis. Disease was self-limiting, characterized by abdominal discomfort, diarrhoea, and in some cases, vomiting. Originating from a rural area and having had previously handled ruminants were associated with a significant risk reduction in males. All the three students who reported chronic use of steroid inhalers for treatment of asthma were cases. This case highlighted, once again, the potential hazard for explosive outbreaks of cryptosporidiosis.     

Cryptosporidiosis in Wisconsin: a case-control study of post-outbreak transmission.

During March-April 1993, an estimated 403000 residents of the 5-county greater Milwaukee, Wisconsin area developed cryptosporidiosis after drinking contaminated municipal water. Although the number of cases dropped precipitously after the implicated water plant closed on 9 April, cases continued to occur. To investigate risk factors for post-outbreak cryptosporidiosis, 33 Milwaukee-area residents who had laboratory-confirmed Cryptosporidium infection with onset of diarrhoea between 1 May and 27 June 1993 were interviewed by telephone. Of these, 28 (85%) had onset of diarrhoea during May, 12 (36%) had watery diarrhoea during the outbreak, and 5(15%) were HIV-infected. In a neighbourhood-matched case-control study, immunosuppression (matched odds ratio (MOR) not calculable, 95% confidence interval (CI) 3.0, infinity) and having a child less than 5 years old in the household (MOR = 17.0, CI 2.0, 395.0) were independently associated with infection. When persons who had diarrhoea during the outbreak were excluded, immunosuppression remained significantly associated with illness (MOR not calculable, CI 1.6, infinity). Cryptosporidium transmission continued after this massive waterborne outbreak but decreased rapidly within 2 months.     

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.     

Recurrent outbreaks of cryptosporidiosis associated with calves among students at an educational farm programme, Minnesota, 2003

Enteric illness outbreaks among middle-/high-school students in consecutive semesters of an educational farm programme were investigated with retrospective cohort studies. During the first outbreak, 31/92 (34%) interviewed students were ill. Risk factors included participating in animal science class (RR 8.1, 95% CI 1.2-55.2) and contact with calves (RR 4.2, 95% CI 1.1-16.2). Stool samples from seven students and two calves yielded Cryptosporidium parvum. Students cared for animals in street clothes and practised poor hand washing. During the second outbreak, 37/81 (46%) interviewed animal science students were ill. Risk factors included having visible manure on hands, and wearing coveralls and boots. Stool samples from seven students and eight calves yielded C. parvum. Student hand washing was still inadequate. Coveralls/boots were cleaned infrequently and removed after hand washing. These outbreaks of cryptosporidiosis resulted from calf contact and inadequate hygiene practices. The failure to adequately implement recommended interventions contributed to the second outbreak.     

浙江省首次发现支原体肺炎爆发流行调查

1985年11~12月,浙江省衢州市某劳改工厂发生一起罕见的支原体肺炎爆发流行。发病102例,罹患率3.3%,无死亡。病人血清冷凝集试验阳性。引起本次流行的传染源是3例散发病人。国内还未见类似报道。     

A community outbreak of Cryptosporidium infection associated with a swimming pool complex

A case-control study was conducted to investigate the cause of a sudden increase in cases of cryptosporidiosis notified to the Brisbane Southside Public Health Unit from January to March 1998. Fifty-two eligible cases were identified over a three-week period early in 1998. Thirty-one of these cases and 21 control subjects participated in the study. Swimming in the 2 weeks before onset of illness was identified as a likely risk factor for cryptosporidiosis infection (OR 3.1, CI 0.8-12.6, P = 0.06). Analysis of swimming pool attendance identified swimming at Pool Complex A as a significant risk factor for the acquisition of cryptosporidiosis (OR 8.9, CI 1.5-67.4, P = 0.004). No other potential risk factors were significantly associated with illness. The detection of cryptosporidium oocysts in three of the four pools at Pool Complex A supported the findings of the case-control study. As a response to this outbreak, Queensland Health has developed a Code of Practice outlining measures for the control and prevention of future outbreaks of swimming pool-associated cryptosporidiosis and/or giardiasis.     

Hepatitis A in south-eastern Sydney 1997-1999: continuing concerns for gay men and an outbreak among illicit drug users

The incidence of hepatitis A virus (HAV) in south-eastern Sydney is one of the highest in Australia with large outbreaks previously associated with male-to-male sexual contact. We report HAV notification trends over the period 1 June 1997 to 31 May 1999 for this location. In the first twelve-month period, 233 cases were notified (crude rate 30.5/100,000 per year) with a peak incidence of 110/100,000 in males aged 20-39 years. Over 60% of male cases reported male-to-male sexual contact. The notification rate (crude rate 15.5/100,000) and proportion of males (61%) was considerably lower in the following twelve month period with 118 cases notified. Less than a third of males reported male-to-male sexual contact. An outbreak (n = 45) of HAV among illicit drug users and their contacts was detected in December 1998. The transmission of HAV remains endemic in south-eastern Sydney. Vaccination among high-risk groups remains an important preventive strategy.     

Measles outbreak in a vaccinated school population: epidemiology, chains of transmission and the role of vaccine failures

An outbreak of measles occurred in a high school with a documented vaccination level of 98 per cent. Nineteen (70 per cent) of the cases were students who had histories of measles vaccination at 12 months of age or older and are therefore considered vaccine failures. Persons who were unimmunized or immunized at less than 12 months of age had substantially higher attack rates compared to those immunized on or after 12 months of age. Vaccine failures among apparently adequately vaccinated individuals were sources of infection for at least 48 per cent of the cases in the outbreak. There was no evidence to suggest that waning immunity was a contributing factor among the vaccine failures. Close contact with cases of measles in the high school, source or provider of vaccine, sharing common activities or classes with cases, and verification of the vaccination history were not significant risk factors in the outbreak. The outbreak subsided spontaneously after four generations of illness in the school and demonstrates that when measles is introduced in a highly vaccinated population, vaccine failures may play some role in transmission but that such transmission is not usually sustained.     

Use of passive surveillance data to study temporal and spatial variation in the incidence of giardiasis and cryptosporidiosis

OBJECTIVE: The goal of this study was to evaluate temporal and spatial variations in the reporting of cases of giardiasis and cryptosporidiosis to a passive surveillance system, and to assess the relationship of those variations to source of drinking water, adjusting for socioeconomic variables. METHODS: The authors analyzed temporal and spatial patterns for 4,058 cases of giardiasis and 230 cases of cryptosporidiosis reported to the Massachusetts Department of Public Health for 1993-1996. They linked each reported case to a database containing information on source of residential water supply and socioeconomic characteristics and evaluated the association between these factors and reporting rates using regression techniques. RESULTS: Reports of giardiasis and cryptosporidiosis were highest for the mixed unfiltered drinking water supply category. Reports of giardiasis were associated with income levels. Increases in reporting for both giardiasis and cryptosporidiosis were seen in summer to early fall. During a suspected outbreak of cryptosporidiosis n the city of Worcester in 1995, a significant increase in reported cases was also observed in the Boston metropolitan area. Following the suspected outbreak, weekly giardiasis rates increased slightly in Worcester and the Boston metropolitan area, while reporting of cryptosporidiosis increased dramatically. CONCLUSIONS: Consistently collected passive surveillance data have the potential to provide valuable information on the temporal variation of disease incidence as well as geographic factors. However, passive surveillance data, particularly in the initial period of surveillance, may be highly sensitive to patterns of diagnosis and reporting and should be interpreted with caution.     

The evaluation of web-based data collection for enhanced surveillance of cryptosporidiosis

Following an increase in the number of people diagnosed with cryptosporidiosis in November 2005, the Communicable Diseases Branch initiated enhanced surveillance using a developmental version of NetEpi Collection, an open-source, web-based data collection tool. We evaluated the usefulness of NetEpi Collection for enhanced surveillance, using the Centers for Disease Control and Prevention's Updated Guidelines for Evaluating Public Health Surveillance Systems as a guide. Most staff (73 per cent) who used NetEpi Collection found it easy to use. Although ongoing support was thought to be adequate by 82 per cent of respondents who used NetEpi Collection, 36 per cent reported that training was limited and 27 per cent reported technical problems such as internet, server and password problems. In order to improve its usefulness in enhanced surveillance, training in NetEpi Collection should be enhanced and the stability of the system improved.     

Rabies in Poland in 2003

In Poland 399 cases of animal rabies were reported in 2003. Mass oral vaccination of wild animals against rabies, which was introduced in 1993, seems to show a positive impact on the epizootic situation of rabies in Poland. In 2003 we observed about three-fold decrease in number of animal rabies cases. The outbreak of animal rabies, which started in 2001 in Wielkopolskie voivodeship, was still present. About 42% of rabies cases were reported from this province. Moreover sources of wild and domestic animal rabies are present in the north-east, east, and south-east of the country. Out of 7 155 persons vaccinated in Poland against rabies, 519 (7%) were bitten by or had contact with a rabid animal. Main reason for vaccination against rabies was exposure to an animal category C--rabies not excluded (5 790 cases, 81%) or category D--animals healthy at the moment of an exposition (846 cases, 12%).     

Serological analysis of a cryptosporidiosis epidemic

BACKGROUND: A cryptosporidiosis epidemic occurred among residents and visitors to Collingwood, Ontario, during March 1996. Fifty-five per cent of 36 confirmed cases were Collingwood visitors and 57% of Collingwood resident cases were under 10 years of age. The low level of reported diarrhoeal illness among adult Collingwood residents caused government officials and physicians to question whether an epidemic had occurred in Collingwood. METHODS: To better evaluate the extent of the epidemic, anonymous surplus sera from 89 adult Collingwood residents, collected for routine tests prior to, during and after the epidemic, and from 80 adult Toronto residents were tested using a Western blot assay for IgG antibody response to two Cryptosporidium antigen groups (15/17-kDa and 27-kDa). RESULTS: For sera collected from 1 January 1996 to 17 June 1996, a higher fraction of Collingwood residents had a detectable serological response (P < 0.002) and the mean intensity of serological responses was higher for Collingwood than Toronto residents (P < 0.001). The mean intensity of serological responses for Collingwood residents was higher in specimens drawn during the 8 weeks following the initial case reports compared to those drawn before or after this period (15/17-kDa, P < 0.02; 27-kDa, P < 0.10). CONCLUSIONS: These elevated serological responses indicate that Cryptosporidium infections among Collingwood residents likely occurred more commonly than illness reports suggested, consistent with a community-wide cryptosporidiosis epidemic. Similar studies should be considered in future suspected cryptosporidiosis epidemic investigations.     

Epidemiological features and control of an outbreak of scarlet fever in a Perth primary school

Scarlet fever was associated with feared outbreaks and mortality in the 19th Century. It occurs sporadically in modern society and infection is readily treated with antibiotics. We report on a scarlet fever outbreak in children attending a primary school in Perth, Western Australia, in late 2003. A total of 13 cases were identified over a five week period. Six of the cases were pre-primary children (ages 4 to 5) from the same class of 26 children (attack rate 23.1%). Three of the remaining seven cases were older siblings of pre-primary cases who developed scarlet fever after their younger siblings. Screening of the children and teachers from the two pre-primary classes at the school yielded 12 positive pharyngeal swabs for group A Streptococcus. Emm-typing of the screening isolates indicated that a common strain was circulating within the outbreak pre-primary class, with four of six isolates identified as emm-type 3. The overall group A Streptococcus carriage rate in screened students in this class was 31.6 per cent and the carriage rate for emm-type 3 was 21.1 per cent. Carriers were treated with oral penicillin V to eradicate carriage and control the outbreak. No further cases of scarlet fever were reported after the treatment of pharyngeal carriers. Outbreaks of scarlet fever still occur in young children and identification and treatment of carriers may still be valuable.     

Epidemiology and control of staphylococcal pyoderma among newborn infants: evaluation of a method for routine cord care with 4 per cent chlorhexidine-detergent solution

The incidence and types of staphylococcal purulent lesions were prospectively studied among 3602 newborn infants. During an epidemic of post-discharge pyoderma, 87 per cent of all Staphylococcus aureus isolates from lesions could be traced to the nursery. The risk of post-discharge disease was related to the degree of staphylococcal skin colonization in the nursery. A method for routine cord care in the nursery with 4 per cent chlorhexidine-detergent solution was evaluated and proved to be effective in reducing staphylococcal colonization in the nursery as well as purulent skin disease at home. The clinical effectiveness of the regimen was followed up for 19 months and a persistent low infection rate was obtained among infants in the post-discharge period.     

Rabies in Poland in 2001

In Poland in 2001, no case of human rabies was reported. Mass oral vaccination of wild animals against rabies, which was introduced in 1993, seems to show a positive impact on the epizootic situation of rabies in Poland. However, this year is the second one when we observed an increase in number of animal rabies cases. This year outbreak of animal rabies starts in Wielkopolskie voivodeship where we observed six-fold increase of animal rabies cases. Moreover sources of wild and domestic animal rabies are present on the north-east, east, and south-east of the country. Out of 9210 persons vaccinated in Poland against rabies, 3080 (33%) were bitten by or were in contact with a rabid animal. Main reason for vaccination against rabies was exposure to an animal category C--rabies not excluded (6747 cases, 73%) or category D--animals healthy at the moment of an exposition (1147 cases, 12%).     

Can syndromic surveillance data detect local outbreaks of communicable disease? A model using a historical cryptosporidiosis outbreak

A national UK surveillance system currently uses data from a health helpline (NHS Direct) in an attempt to provide early warning of a bio-terrorist attack, or an outbreak caused by a more common infection. To test this syndromic surveillance system we superimposed data from a historical outbreak of cryptosporidiosis onto a statistical model of NHS Direct call data. We modelled whether calls about diarrhoea (a proxy for cryptosporidiosis) exceeded a statistical threshold, thus alerting the surveillance team to the outbreak. On the date that the public health team were first notified of the outbreak our model predicted a 4% chance of detection when we assumed that one-twentieth of cryptosporidiosis cases telephoned the helpline. This rose to a 72% chance when we assumed nine-tenths of cases telephoned. The NHS Direct surveillance system is currently unlikely to detect an event similar to the cryptosporidiosis outbreak used here and may be most suited to detecting more widespread rises in syndromes in the community, as previously demonstrated. However, the expected rise in NHS Direct call rates, should improve early warning of outbreaks using call data.     

Modelling the transmission dynamics of acute haemorrhagic conjunctivitis: application to the 2003 outbreak in Mexico

We model an outbreak of acute haemorrhagic conjunctivitis (AHC) using a simple epidemic model that includes susceptible, infectious, reported, and recovered classes. The model's framework considers the impact of underreporting and behaviour changes on the transmission rate and is applied to a recent epidemic of AHC in Mexico, using a fit to the cumulative number of cases to estimate model parameters, which agree with those derived from clinical studies. The model predicts a 'mean time from symptomatic onset to diagnosis' of 1.43 days (95 per cent CI: 1-2.5) and that the final size of the Mexican epidemic was underreported by 39 per cent. We estimate that a primary infectious case generates approximately 3 secondary cases (R0* = 2.64, SD 0.65). We explore the impact of interventions on the final epidemic size, and estimate a 36 per cent reduction in the transmission rate due to behaviour changes. The effectiveness of the behaviour changes in slowing the epidemic is evident at 21.90 (SD 0.19) days after the first reported case. Results therefore support current public health policy including expeditious announcement of the outbreak and public health information press releases that instruct individuals on avoiding contagion and encourage them to seek diagnosis in hospital clinics.     

Multi-drug resistant Salmonella Java infections acquired from tropical fish aquariums, Australia, 2003-04

Antibiotic resistant Salmonella infections are rare in Australia. We investigated an increase in multidrug resistant Salmonella Paratyphi B biovar Java (S. Java) infections in Australia during 2003-04. Eighty-two per cent (18/22) of S. Java cases enrolled into the study reported that they had been in contact with aquariums housing fish during their incubation period. Seventy-two per cent (13/18) of cases were infected with strains that were resistant to ApSmTcCmSuSp (ampicillin, streptomycin, tetracycline, chloramphenicol, sulfonamides, spectinomycin). Case households commonly reported high risk behaviours, such as cleaning aquaria in sinks. Sixty-one per cent (11/18) of cases reported that fish in their aquarium had been sick or died in the week prior to their illness, and S. Java was isolated from the water or gravel of 5 cases. These antibiotic strains are being spread internationally and may become endemic in countries importing tropical fish or result in transfer of resistance to other more common Salmonella serotypes.     

Recurrent outbreaks of giardiasis in a child day care center, Wisconsin.

In the 19-month period September 1983-March 1985, three outbreaks of giardiasis occurred in one large child day care center. Control measures instituted during each outbreak included case finding; pharmacologic treatment and follow-up testing of stool specimens for cases of giardia infection in day care children and staff, and their household contacts; facilitating and stressing personal and environmental hygiene, including altering diapering practices and teaching appropriate hand washing techniques. In the first, second, and third outbreaks, overall attack rates (stool analysis positive for Giardia lamblia) were determined for those persons with greater than or equal to 2 stool specimens submitted; attack rates in children were 47, 17, and 37 per cent, respectively; for tested staff, the rates were 35, 13, and 9 per cent; and for tested household contacts were 18, 9, and 5 per cent. Attack rates were highest for ambulatory diapered children, children attending the day care center greater than or equal to 40 hours per week, and children who were infected with G. lamblia in the most recent previous outbreak. Despite extensive efforts to identify cases, a cure rate of greater than 90 per cent in treated cases, and improvements in personal and environmental hygiene practices, G. lamblia infections recurred in outbreak proportions.