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PubMed1997

An outbreak of invasive group A streptococcal disease associated with high carriage rates of the invasive clone among school-aged children.

OBJECTIVES: To determine if a common strain of group A streptococcus was responsible for an outbreak of invasive streptococcal disease in southeastern Minnesota and to determine whether this strain was prevalent among residents of this area during the outbreak who either had streptococcal pharyngitis or were asymptomatic streptococcal carriers. DESIGN: Pharyngeal culture survey and case-contact evaluation. SETTING: Three adjacent counties in southeastern Minnesota defined as the outbreak area. Outbreak period, January 1 through March 31, 1995. PATIENTS: Seven patients with invasive streptococcal infection, 1249 patients (adults and children) with sore throat who resided in the outbreak area, children from an elementary school located in 1 community where the majority of invasive cases occurred, and 896 students from 3 schools located in Minnesota counties outside the outbreak area. MEASUREMENTS: Pulsed-field gel electrophoresis (DNA fingerprinting) of group A streptococcal isolates obtained from patients with invasive disease, throat swabs of patients with sore throat, and throat swabs of asymptomatic school-aged children. RESULTS: All patients with outbreak-associated invasive disease had group A streptococcal isolates that were indistinguishable by pulsed-field gel electrophoresis. Additional testing showed that these isolates carried significant virulence factors including pyrogenic exotoxin A and streptococcal superantigen. Five of these 7 patients with invasive disease had underlying medical conditions; 4 developed toxic shock syndrome and died (case fatality, 57%). The outbreak-associated group A streptococcal clone was found in 69 (26.5%) of the 260 patients with sore throat from whom group A streptococcus was isolated. The frequency of the outbreak clone among pharyngeal carriers from the 3 schools outside the outbreak area was significantly less (range, 0%-10%) than in children from the school in the outbreak area (78%; relative risk, 29; 95% confidence interval, 11.1-78.1; P<.001). Four of the 7 patients with outbreak-associated disease had contact with children who attended the school in the outbreak area. CONCLUSIONS: A single clone of group A streptococcus was responsible for 7 cases of invasive streptococcal disease during an outbreak in Minnesota and for a significant number of pharyngitis cases that also occurred during the outbreak. Invasive disease occurred most frequently in persons with underlying medical conditions. This outbreak was also associated with increased carriage rates of the invasive streptococcal clone among community school-aged children. Cases of invasive group A streptococcal infection may therefore reflect the tip of the iceberg with regard to the burden of colonization of a specific invasive streptococcal clone in a community.

Adult↗
PubMed1998

Outbreaks of waterborne infectious intestinal disease in England and Wales, 1992-5.

Following the introduction of an improved surveillance system for infectious intestinal disease outbreaks in England and Wales, the Public Health Laboratory Service Communicable Disease Surveillance Centre received reports of 26 outbreaks between 1 January 1992 and 31 December 1995 in which there was evidence for waterborne transmission of infection. In these 26 outbreaks, 1756 laboratory confirmed cases were identified of whom 69 (4%) were admitted to hospital. In 19 outbreaks, illness was associated with the consumption of drinking water from public supplies (10 outbreaks) or private supplies (9 outbreaks). The largest outbreak consisted of 575 cases. In 4 of the remaining 7 outbreaks, illness was associated with exposure to swimming pool water. Cryptosporidium was identified as the probable causative organism in all 14 outbreaks associated with public water supplies and swimming pools. Campylobacter was responsible for most outbreaks associated with private water supplies. This review confirms a continuing risk of cryptosporidiosis from chlorinated water supplies in England and Wales, and reinforces governmental advice to water utilities that water treatment processes should be rigorously applied to ensure effective particle removal. High standards of surveillance are important for prompt recognition of outbreaks and institution of control measures. As microbiological evidence of water contamination may be absent or insufficient to implicate a particular water supply, a high standard of epidemiological investigation is recommended in all outbreaks of suspected waterborne disease.

Communicable Diseases↗
PubMed1995

An outbreak of occupational dermatosis in an electronics store.

An outbreak of skin disorders was noted by the primary care physician responsible for the health care of 52 employees in an electronics store. The cases occurred after termite treatment of the store, and the breakdown of the air-conditioning system in several areas in the store. Investigations were initiated to allay worker concern that the chemicals used for termite treatment (in particular, arsenic trioxide) were responsible for the outbreak. 9 of the 52 workers were found to have heat rash (miliaria rubra). 21% (7) of workers who worked in non-air-conditioned areas had heat rashes, as compared to 11% (2) of workers who worked in air-conditioned work zones. 2 workers had contact dermatitis due to exposure to greaseless lubricant, and 8 other workers had a non-work-related skin disorder. Indoor wet bulb globe temperature index measurements in the non-air conditioned areas were within threshold limit values, but ventilation in these areas was very poor. 2 environmental samples had non-detectable limits of arsenic.

Air Conditioning↗
PubMed1990

An outbreak of human Semliki Forest virus infections in Central African Republic.

Semliki Forest (SF) virus was responsible for an outbreak of febrile illnesses in Bangui, Central African Republic (CAR), during October-December 1987. The virus was isolated at first from mosquitoes, mainly Aedes africanus, collected August-October in a gallery forest 100 km from Bangui. During October-December, 22 isolations of SF virus were made from serum samples collected from patients in Bangui presenting with fever, severe persistent headache, myalgia, arthralgia, and a convalescence marked by asthenia. During the same period, 8 SF virus isolates were obtained from mosquitoes collected in Bangui, mainly from Ae. aegypti. Europeans, particularly soldiers who had recently arrived from France, were affected. Antibodies to alphaviruses had been previously detected in a high proportion of resident human populations in CAR. We conclude that SF virus is a human pathogen.

Aedes↗
PubMed1995

Emergence of nalidixic acid resistant Shigella dysenteriae type 1 in Thailand: an outbreak associated with consumption of a coconut milk dessert.

BACKGROUND: Although Shigella dysenteriae type 1 has been responsible for large outbreaks of severe dysentery in many parts of Asia, relatively few cases of this disease have been reported from Thailand and have generally not involved nalidixic acid resistant strains. METHODS: Beginning March 1991, all patients with diarrhoea seen at the hospital outpatient department (OPD) in Suan Phung, Thailand (a western district near the Burmese border) were cultured for enteric pathogens. Shigella dysenteriae 1 was first recognized in July 1992, and an OPD-based case-control study was conducted to pinpoint the source of the outbreak in the community. For each case of culture confirmed S. dysenteriae 1, one control person without diarrhoea, matched by age and date of visit, was randomly selected from the OPD registry. RESULTS: Of 197 patients treated for diarrhoea at the hospital OPD in July and August 1992, 79 (40%) had bloody diarrhoea, compared with 86/561 (15%) patients seen during 16 months of previous surveillance (P < 0.0001). Shigella dysenteriae 1 was isolated from 33/197 (17%) patients. Compared to matched controls, patients with S. dysenteriae 1 were more likely to attend one of the local elementary schools (odds ratio = 6.74, P = 0.025), or live in the community surrounding this school (odds ratio for non-school age people = 18.0, P = 0.008). A cross-sectional study conducted at the school indicated that 50 (10%) of 485 students had dysentery in July. A coconut milk dessert prepared at the school was identified as the vehicle of transmission (relative risk = 24.9, P < 0.0001). CONCLUSIONS: Nalidixic acid resistant S. dysenteriae 1 emerged in a community in Thailand, and was traced to a point source outbreak at a local school.

Adolescent↗
PubMed1979

Evaluation of a neuraminidase-specific influenza A virus vaccine in children: antibody responses and effects on two successive outbreaks of natural infection.

Three groups of children were immunized with an inactivated Port Chalmers (H3ChN2Ch) influenza vaccine (group A), a neuraminidase-specific (Heq1N2Ch) influenza vaccine (group B), or a placebo. Immunization induced seroconversion for H3Ch and N2Ch-specific antibody in group A and for N2Ch antibody in group B. The protective efficacies observed against naturally acquired illness with the Port Chalmers strain of influneza A virus were 68.7% and 37.4% in groups A and B, respectively, in comparison to the placebo group, and those against illness produced by the subsequent outbreak of the Victoria strain were 80.0% and 72.7%. These data support the role of neuraminidase-specific immunization in protection against influenza. Although the degree of protection after vaccination with the Heq1N2Ch vaccine was less than that provided by the biphasic H3ChN2Ch vaccine against the Port Chalmers strain, it appeared to be similar in the two vaccine study groups against the Victoria strain.

Adolescent↗
PubMed1989

The influence of seasonal temperatures on the natural regulation of the screwworm, Cochliomyia hominivorax, in the southern U.S.A.

The incidence of screwworm cases in Texas during the 1962-82 sterile-male eradication campaign is analysed in relation to seasonal temperatures and screwworm density. The analysis shows that screwworm outbreaks occur in response to favourable seasonal conditions, especially warm winters and cool summers. The outbreaks collapse following cold winters and hot summers. Screwworm density in autumn also influences rates of increase, possibly through a shortage of wounded hosts in the autumn-winter period. The analysis provides a simple predictive model which not only accounts for the fluctuations in case incidence seen in Texas during the eradication campaign, which others have attributed to strain problems and release methods, but also simulates the historical pattern of screwworm abundance in both Texas and Florida over the last 100 years. It is concluded that screwworm, being essentially a tropical species, might well have been eradicated from the southern U.S.A. by exceptionally unfavourable climate such as occurred in Florida in 1958 and in Texas in the late 1970s and early 1980s. Certainly, unfavourable climate must have been important to the success of the eradication campaigns.

Animals↗
PubMed1981

Salmonella and shigella surveillance in Hungary, 1972-1976. II. Shigella surveillance.

Shigellae were isolated from 32 399 persons in the bacteriological laboratories of the Public Health Stations between 1972-1976. The number of isolations ranged between 5325 and 8237 yearly. As S. dysenteriae and S. boydii serotypes occurred only in about 1.5% of all isolations, the epidemiological situation was determined by the incidence of S. flexneri and S. sonnei. Except in 1973, S. sonnei constituted the majority in every year. S. sonnei predominance, observed first in the western regions of the country, showed a gradual eastward spread and became characteristic of all localities in 1975-1976. The July-September peak of shigella isolations was associated with S. sonnei, as S. flexneri was distributed practically evenly in every season. The incidence of shigella isolations per 100 000 inhabitants was the lowest in the middle and the highest in the northern parts of the country. Sporadic cases were somewhat more frequent than epidemic outbreaks. Shigellae were isolated in 64.1% from patients and in 35.9% from asymptomatic excreters. The patient : excreter ratio was higher for S. sonnei (70.2 : 29.8) than for S. flexneri (54.6 : 45.4). In the survey period, 14 692 isolations were made in the course of 3278 epidemics; out of these, 11 171 cases were involved in 574 extensive outbreaks. S. sonnei was responsible mainly for school and nursery outbreaks, whereas S. flexneri dysentery predominated in mental wards and in homes for the aged and for mentally retarded children. The prevalent types of S. flexneri were (serological/phage type): 2a/69, 3a/5, 3a/19, 4a/81, 4a/89d and 6/85. The prevalent epidemiological subunits of S. sonnei were (phage/colicin type): 2/0, 2/6, 2/12, 3/12, 6/0, 7/0, 65/0, 65/6 and 65/12.

Adult↗
PubMed1999

Molecular analysis of Pseudomonas aeruginosa: epidemiological investigation of mastitis outbreaks in Irish dairy herds.

Pseudomonas aeruginosa is a pathogen in both humans and animals. This bacterium, most often associated with respiratory infections in cystic fibrosis patients, was found to be the causative agent in bovine mastitis outbreaks among 11 Irish dairy herds. Epidemiological findings suggested that the infection was spread to all herds by teat wipes that had been contaminated with this organism. Two molecular-typing strategies were used in an attempt to determine the genomic relationship(s), if any, of the P. aeruginosa strains isolated from the various herds and to verify whether the same strain was responsible for each outbreak. Thirty-six isolates from the mastitis outbreaks were tested and compared to fourteen clinical isolates from Cork University Hospital. With one exception, all outbreak-linked strains produced identical patterns when ribotyped with ClaI and PvuII enzymes. Eight of the clinical isolates gave the same ClaI ribotype pattern as the mastitis-causing strains. However, PvuII proved more discriminatory, with only the outbreak isolates producing identical patterns. Similar results were obtained with RW3A-primed DNA amplification fingerprinting, with all outbreak isolates except one displaying the same fingerprint array. The clinical strains produced several fingerprint patterns, all of which were different from those of the mastitis-causing isolates. Fine-resolution DNA fingerprinting with a fluorescence-labelled RW3A primer also identified a number of low-molecular-weight polymorphisms that would have remained undetected by conventional methods. These data support the view that the same P. aeruginosa strain was responsible for the mastitis outbreaks in all 11 herds.

Animals↗
PubMed1994

Anti-rotavirus G type-specific and isotype-specific antibodies in children with natural rotavirus infections.

Serum VP7 (G) type- and isotype-specific anti-rotavirus antibodies were assessed among children monitored longitudinally over one or two rotavirus seasons in day care centers. Seventy-five pairs of blood specimens from 63 children were tested for anti-rotavirus antibodies. Stool specimens were collected weekly and tested for rotavirus antigen. G typing of detected rotaviruses showed that seven outbreaks of G1 and one of G3 occurred during the two seasons. G type-specific responses to the outbreak strain occurred among 79% of infected children and 9% of children with infection not detected (P < .001). Of children infected with G1, 54% had a heterotypic response; they were older (P = .048) and had higher preexisting G1 antibody levels than children who had only homotypic responses (P = .012). Higher IgA, IgG, and homotypic antibody levels to the antigenic site C of the G1 and G3 VP7s correlated with protection against infection and illness, homotypic antibody independently of IgA or IgG titers.

Antibodies, Viral↗
PubMed1998

Hepatitis A vaccination of men who have sex with men--Atlanta, Georgia, 1996-1997.

Outbreaks of hepatitis A among men who have sex with men (MSM) are a recurring problem in many large cities in the industrialized world. Because MSM are at high risk for acquiring hepatitis A, in 1995 the Advisory Committee on Immunization Practices (ACIP) recommended that MSM be vaccinated against hepatitis A. These recommendations have not been implemented widely, even in outbreak settings. This report summarizes the investigation of an ongoing outbreak of hepatitis A among MSM in Atlanta, Georgia, and a public health vaccination campaign in response to the outbreak.

Adult↗
PubMed1993

Human immune responses to the Plasmodium falciparum ring-infected erythrocyte surface antigen (Pf155/RESA) after a decrease in malaria transmission in Madagascar.

A resurgence of falciparum malaria occurred in the central highlands of Madagascar in the 1980s and was responsible for an outbreak in 1986-1987. Since 1989, transmission has decreased dramatically. In April 1991, we investigated the humoral and cellular immune responses of 53 inhabitants of the village of Manarintsoa to six synthetic peptides that reproduced the major B and/or T cell epitopes of the Pfl 55/ring-infected erythrocyte surface antigen (RESA) of Plasmodium falciparum. The presence of RESA peptide-reactive T cells was assessed by lymphocyte proliferation assay as well as by detection of in vitro production of interferon-gamma and interleukin-2. The mean values of these cellular responses were low, and the results obtained in these three tests showed no correlation. Twenty-seven subjects presented with anti-RESA antibodies as detected by modified immunofluorescent assay, but the mean levels of anti-peptide antibodies were low. When compared with data obtained in January 1988 from the same subjects with three of the six peptides, the present data demonstrated a decrease in the response to these peptides in terms of both proliferative response and mean antibody titers. The mean values of anti-RESA antibodies remained unchanged. The fact that cellular and humoral responses to the major Pfl 55/RESA epitopes decreased but did not disappear probably reflects both the remainder of the acquired immunity resulting from the 1986-1987 malaria outbreak, and its conservation by the very low level of transmission since 1989.

Adolescent↗
PubMed1987

Campylobacter etiology in human gastroenteritis demonstrated by antibodies to acid extract antigen.

Campylobacter antibodies of the immunoglobulin G (IgG), IgM, and IgA classes were determined by enzyme immunoassay with acid glycine extract antigen in patients and controls involved in two Campylobacter outbreaks and in 266 unselected patients with acute enteritis. The assay showed a specificity of 99% for each immunoglobulin class in sera from 200 healthy blood donors. Elevated Campylobacter antibody titers were shown in 97% of stool culture-positive patients involved in the outbreaks. Rapid changes of IgA and IgM Campylobacter antibodies were typical of the early phase of serologic response in the outbreaks and thus offered the best diagnostic value in the serologic diagnosis of acute campylobacteriosis. In unselected patients with acute enteritis, the assay revealed elevated Campylobacter antibody titers in 37 patients, of whom only 12 had had positive Campylobacter stool cultures. In the sera of patients with other bacterial findings in addition to high titers of Campylobacter antibodies, no cross-reacting antibodies were found, but there was evidence of several mixed infections.

Acute Disease↗
PubMed1990

Cholera in Sarawak: a historical perspective (1873-1989).

Cholera has been in existence in Sarawak for many years and since 1873 many major epidemics have occurred. The epidemics usually occur during the dry months of May, June and July and the population affected are those in coastal areas. As in other outbreaks the areas affected were those which had poor environmental sanitation, poor water supply, poor refuse disposal and indiscriminate disposal of faeces. Malays are more affected as in Peninsular Malaysia outbreaks. The classical biotype was common prior to 1961. In later years the El Tor (biotype) has been responsible for most outbreaks.

Cholera↗
PubMed1995

Outbreak of HIV infection in a Scottish prison.

OBJECTIVE--To investigate the possible spread of HIV infection and its route of transmission among prison inmates. DESIGN--In response to an outbreak of acute clinical hepatitis B and two seroconversions to HIV infection, counselling and testing for HIV were offered to all inmates over a two week period in July 1993. Information was sought about drug injecting, sexual behaviour, and previous HIV testing. SETTING--HM Prison Glenochil in Scotland. SUBJECTS--Adult male prisoners. MAIN OUTCOME MEASURES--Uptake of HIV counselling and testing; occurrence and mode of HIV transmission within the prison. RESULTS--Of a total 378 inmates, 227 (60%) were counselled and 162 (43%) tested for HIV. Twelve (7%) of those tested were positive for antibody to HIV. One third (76) of those counselled had injected drugs at some time, of whom 33 (43%) had injected in Glenochil; all 12 seropositive men belonged to this latter group. Thirty two of these 33 had shared needles and syringes in the prison. A further two inmates who injected in the prison were diagnosed as positive for HIV two months previously. Evidence based on sequential results and time of entry into prison indicated that eight transmissions definitely occurred within prison in the first half of 1993. CONCLUSION--This is the first report of an outbreak of HIV infection occurring within a prison. Restricted access to injecting equipment resulted in random sharing and placed injectors at high risk of becoming infected with HIV. Measures to prevent further spread of infection among prison injectors are urgently required.

Adult↗
PubMed1999

Molecular typing methods to investigate transmission of Escherichia coli O157:H7 from cattle to humans.

The utility of phage typing, pulsed-field gel electrophoresis (PFGE), and plasmid profile analysis was compared, to differentiate between Canadian Escherichia coli O157:H7 strains of human (n = 27) and cattle (n = 24) origin. The diversity indices for phage typing, plasmid analysis and PFGE were 0.85, 0.69 and 0.93, respectively. PFGE and phage typing were also applied to study the role of direct transmission of E. coli O157:H7 from cattle to humans on isolates collected from two separate farm outbreaks. PFGE showed that more than one E. coli O157:H7 strain with varying PFGE DNA subtype profiles, may be responsible for an outbreak, and that more than one E. coli O157:H7 subtype may be circulating on a particular farm at any one time. To our knowledge, this is one of the first reports where PFGE typing was used to verify the direct transmission of E. coli O157:H7 from cattle to humans.

Animals↗
PubMedDate not supplied

Patient-care directives and infection control: the potential conflict of interest during epidemics in long-term care facilities.

Patient-care directives in long-term care facilities ensure that the aggressiveness of diagnostic and therapeutic interventions accurately reflects the desires of the patient. The results of our investigation of two outbreaks of fatal respiratory illness in long-term care facilities illustrate how patient-care directives may have delayed response to the outbreaks. Despite a cluster of deaths in each facility, staff delayed collection of laboratory specimens until patients with no directives restricting the medical workup became ill. Directives focus on the needs of the individual patient and family, but when an outbreak occurs, they may conflict with community needs. The challenge for the infection control practitioner is to recognize when community needs outweigh individual desires so that appropriate laboratory investigations can identify the cause of the illness.

Advance Directives↗