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PubMed2005

Vaccine effectiveness during a varicella outbreak among schoolchildren: Utah, 2002-2003.

OBJECTIVES: In the context of a chickenpox outbreak involving 2 Utah elementary schools, we conducted an investigation to assess vaccine effectiveness, describe illness severity, and examine risk factors for breakthrough varicella (ie, varicella in those who have been vaccinated). METHODS: All parents were asked to complete a questionnaire about their child's medical history. Parents of children with recent varicella were interviewed, and vaccination records were verified. Lesions were submitted for polymerase chain reaction testing. RESULTS: Questionnaires were returned for 558 (93%) of 597 students in school A and 924 (97%) of 952 students in school B. A total of 83 schoolchildren (57 unvaccinated and 26 vaccinated) had varicella during the October 2002 through February 2003 outbreak period. An additional 17 cases occurred among household contacts, including infants and adults. Polymerase chain reaction analysis recovered wild-type varicella. Vaccine effectiveness was 87%. With 1 notable exception, vaccinated children tended to have milder illness. Risk factors for breakthrough varicella included eczema, vaccination > or =5 years before the outbreak, and vaccination at < or =18 months of age. Restricting analysis to children vaccinated > or =5 years before the outbreak, those vaccinated at < or =18 months of age were more likely to develop breakthrough varicella (relative risk: 9.3; 95% confidence interval: 1.3-68.9). CONCLUSIONS: The vaccine, administered by >100 health care providers to 571 children during a 7-year time period, was effective. Risk factors for breakthrough varicella suggest some degree of biological interaction between age at vaccination and time since vaccination.

Adult↗

PubMed1993

[Outbreak of malaria induced among users of injectable drugs].

Five cases of malaria were detected among cocaine users by the local health service in Bauru, a city with a population of 260,000, located 324 km from S. Paulo, Brazil, during the first three weeks of July 1990. Autochthonous malaria had not occurred in Bauru since 1978, and all the five cases denied having recently traveled to endemic areas. An extensive epidemiologic survey conducted from July 19 to September 13 revealed that the 5 cases were in fact part of a malaria outbreak among endovenous drug users. Moreover, at least 114 other people, who had in the last three months shared syringes and needles with one or more proved cases, were also involved in the outbreak. One hundred and two people were identified and interviewed orally. The examination of thick smears made from samples collected from 99 of them confirmed 21 cases of vivax malaria. Three people with negative blood smears had an indirect immunofluorescent assay positive to P. vivax antigen. Although the index case could not be discovered, the investigation suggested that one or more people who had recently traveled to the Amazon region might have introduced the disease. The control of the outbreak was achieved after offering treatment with chloroquine (10 tablets) to confirmed cases and contacts, followed by weekly suppressive chloroquine (2 tablets) until the last contact was detected. Malaria examination of 91 blood samples also revealed a high prevalence of hepatitis B virus infection (40%) and HIV infection (58%) among those involved in the outbreak. The strategy used to identify the cases and the contacts and the difficulties overcome in carrying it through are described.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗

PubMed1995

[Food poisoning outbreak caused by Salmonella Enteritidis in the northwest of São Paulo State, Brazil].

A foodborne outbreak which affected 211 persons occurred, in a School, in 1993. The epidemiological data obtained by interviewing the affected and non affected persons sampled showed as predominant symptoms: diarrhoea, fever (77.7%), abdominal cramps (67.7%), vomiting (65.8%), hot-and-cold sensations (54.5%) and headache (44.5%). The median incubation period was of 17 hours, the limits being 3 and 29 hours. The disease period was of from 3 to 4 days. The food concerned was a kind of paté, a mayonnaise mixture prepared with fresh eggs with boiled potatoes that was consumed with bread. The biological material analysis-3 coprocultures, and leftovers of the food revealed the presence of one and the same organism: Salmonella Enteritidis. In the food, the numbers of this bacterium per gram were sufficient to account for the manifestation of the disease (10(4) and 10(5)g). The antibiogram of all th isolates showed the same sensibility pattern. The preparation related to this outbreak suggests the endogenous contamination of the eggs; the cross contamination-the outbreak affected three school periods, as the food was prepared separately for each school period; and the conditions under which the food was kept during the time from preparation to consumption. The observation of the 3 food handlers, by successive coprocultures, for one week, indicates that they were not asymptomatic carriers nor were they affected as a result of this outbreak by the causal bacteria.

Adolescent↗

PubMed1998

[Food borne disease outbreaks caused by Salmonella enteritidis].

OBJECTIVE: It is to describe outbreaks of salmonellosis reported from July 1993 through June 1997 in the Northwest region of S. Paulo State, Brazil, one of the areas where several foodborne outbreaks of salmonellosis have been recently detected. METHOD: Data of 19 epidemiological investigations were analysed; 87 stool specimens and 38 food samples (including 12 of shell eggs) were processed for microbiological analysis. Salmonella strains were identified by serotyping, phagetyping and antimicrobial susceptibility testing. RESULTS: There were 906 ill persons including 295 hospitalized patients. Phage type 4 (PT 4) Salmonella Enteritidis strains were isolated from 80.5% of stool samples, from all food samples and from 41.7% of eggs. Of the outbreaks, 95.7% were associated with the consumption of food containing raw or undercooked eggs. All strains were susceptible to the 13 antimicrobials, except the strains from the nosocomial outbreak. CONCLUSIONS: The results obtained show the need for the implementation of control measures regarding egg and storage, as well as for guidance to the public as to the risks involved in the consumption of inadequately prepared eggs.

Aged↗

PubMedDate not supplied

[Nosocomial and community outbreak of epidemic keratoconjunctivitis in Navarra in 1996].

BACKGROUND: Epidemic keratoconjunctivitis is an acute, generally bilateral infection, that appears sporadically or in outbreaks from a source of common infection which may be a visit to the ophthalmologist or a swimming pool. Keratitis may evolve to form sub-epithelial injuries in the cornea lasting as much as several months. METHODS: Description of an outbreak of epidemic keratoconjunctivitis that took place in Navarra (Spain) between April and August 1996 and which affected at least 266 people. RESULTS: The epidemiological research highlights the existence of two ophthalmologist consulting rooms as the transmission mechanism for the infection in 46 of the 116 patients researched. The spread of the infection in the environment of the patients was recorded in 119 cases, 62 of which are considered secondary cases. The aetiological diagnosis of the outbreak was carried out 11 days after the start of the microbiological research, isolating adenovirus in conjunctival samples of 8 of the 19 patients researched. CONCLUSIONS: The preventive measures taken to control the outbreak and their effectiveness was highlighted by the gradual reduction in cases.

Adenovirus Infections, Human↗

PubMed2006

Multilocus genotyping of Cryptosporidium hominis associated with diarrhea outbreak in a day care unit in São Paulo.

UNLABELLED: A number of species of Cryptosporidium are associated with diarrhea worldwide. Little data exists regarding the genotypes and species of Cryptosporidium associated with cases of infections in Brazil. PURPOSE: In the present study, we ascertained by molecular methods the species and the genotype of Cryptosporidium sp from a diarrhea outbreak diagnosed in a day care at the Hospital Clínicas, São Paulo University Medical School. MATERIALS AND METHODS: Specific identification and typing of the isolates associated with the outbreak was done by DNA sequencing analysis of fragments amplified by polymerase chain reaction (PCR) from 3 different Cryptosporidium loci: the SSUrRNA coding region, the Cryptosporidium oocyst wall protein (COWP) gene, and the microsatellite locus 1 (ML1), a tandem GAG-trinucleotide repeat containing substitutions that differentiate the genotypes of Cryptosporidium parvum and Cryptosporidium hominis. RESULTS: A total of 29 positive samples from the outbreak were studied by the molecular methods described. Our study revealed the presence of a single genotype of Cryptosporidium hominis in all samples. CONCLUSION: The molecular analysis reinforced the hypothesis that the transmission of Cryptosporidium hominis during the period the samples were collected occurred in an outbreak pattern, possibly by person-to-person contact through the fecal-oral route. As far as we know, this is the first time that molecular tools have been used to identify the species and the genotype of isolates showing the presence of the ML1 genotype in samples from Brazilian patients.

Animals↗

PubMed2003

Epidemiology, production losses, and control measures associated with an outbreak of avian influenza subtype H7N2 in Pennsylvania (1996-98).

An outbreak of H7N2 low-pathogenicity (LP) avian influenza (AI) occurred in a two-county area in Pennsylvania from December of 1996 through April of 1998. The outbreak resulted in infection of 2,623,116 commercial birds on 25 premises encompassing 47 flocks. Twenty-one (one premise with infection twice) of the twenty-five infected premises housed egg-laying chickens and one premise each had turkeys, layer pullets, quail, and a mixed backyard dealer flock. Despite dose proximity of infected flocks to commercial broiler flocks, no infected broilers were identified. Experimentally, when market age broilers were placed on an influenza-infected premise they seroconverted and developed oviduct lesions. The outbreak was believed to have originated from two separate introductions into commercial layer flocks from premises and by individuals dealing in sales of live fowl in the metropolitan New York and New Jersey live-bird markets. Source flocks for these markets are primarily in the northeast and mid-Atlantic areas, including Pennsylvania. Mixed fowl sold include ducks, geese, guinea hens, quail, chukar partridges, and a variety of chickens grown on perhaps hundreds of small farms. Infections with the H7N2 AI virus were associated with variable morbidity and temporary decreases in egg production ranging from 1.6% to 29.1% in commercial egg-laying chickens. Egg production losses averaged 4.0 weeks duration. Mortality ranged from 1.5 to 18.3 times normal (mean of 4.3 times normal). Duration of mortality ranged from 2 to 13 weeks (average of 3.9 weeks) in flocks not depopulated. Lesions observed were primarily oviducts filled with a mucous and white gelatinous exudates and atypical egg yolk peritonitis. Quarantine of premises and complete depopulation were the early measures employed in control of this outbreak. Epidemiological studies suggested that depopulation furthered the spread of influenza to nearby flocks. Thereafter, later control measures included quarantine, strict biosecurity, and controlled marketing of products.

Animals↗

PubMed2003

Low-pathogenicity H7N2 avian influenza outbreak in Virgnia during 2002.

An outbreak of low-pathogenicity H7N2 avian influenza virus (AIV) in the Shenandoah Valley of Virginia during the spring and summer of 2002 affected 197 farms and resulted in the destruction of over 4.7 million birds. The outbreak affected primarily turkey farms (28 breeders, 125 grow out) with some spillover into chicken farms (29 breeders, 13 grow out, 2 table-egg layers). Although no direct link was established, the strain of H7N2 AIV in this outbreak had a molecular fingerprint that was essentially identical to the H7N2 AIV strain that has circulated in the live bird markets of the northeastern United States for the last 8 yr. After an initial delay caused by lack of viable disposal options, depopulation and disposal, primarily in sanitary landfills, was carried out within 24 hr of detection of a positive flock. Increased surveillance efforts included once-a-week testing of the daily mortality of all poultry farms in the region, testing of all breeder farms every 2 wk, and testing of all flocks prior to movement for any reason. A statistical sampling of backyard flocks and wild birds found no evidence of the virus. The successful eradication of this outbreak was the result of the efforts of a highly effective task force of industry, state, and federal personnel.

Agriculture↗

PubMedDate not supplied

Investigation of H7N2 avian influenza outbreaks in two broiler breeder flocks in Pennsylvania, 2001-02.

An avian influenza (AI) outbreak occurred in meat-type chickens in central Pennsylvania from December 2001 to January 2002. Two broiler breeder flocks were initially infected almost simultaneously in early December. Avian influenza virus (AIV), H7N2 subtype, was isolated from the two premises in our laboratory. The H7N2 isolates were characterized as a low pathogenic strain at the National Veterinary Services Laboratories based on molecular sequencing of the virus hemagglutinin cleavage site and virus challenge studies in specific-pathogen-free leghorn chickens. However, clinical observations and pathologic findings indicated that this H7N2 virus appeared to be significantly pathogenic in meat-type chickens under field conditions. Follow-up investigation indicated that this H7N2 virus spread rapidly within each flock. Within 7 days of the recognized start of the outbreak, over 90% seroconversion was observed in the birds by the hemagglutination inhibition test. A diagnosis of AI was made within 24 hr of bird submission during this outbreak using a combination of virus detection by a same-day dot-enzyme-linked immunosorbent assay and virus isolation in embryonating chicken eggs. Follow-up investigation revealed that heavy virus shedding (90%-100% of birds shedding AIV) occurred between 4 and 7 days after disease onset, and a few birds (15%) continued to shed virus at 13 days post-disease onset, as detected by virus isolation on tracheal and cloacal swabs. AIV was not detected in or on eggs laid by the breeders during the testing phase of the outbreak. The two flocks were depopulated at 14 days after disease onset, and AIV was not detected on the two premises 23 days after depopulation.

Animals↗

PubMed2005

Viral genotyping of infectious bursal disease viruses isolated from the 2002 acute outbreak in Spain and comparison with previous isolates.

An infectious bursal disease (IBD) outbreak occurred in the east region of Spain in the spring of 2002 and rapidly spread thorough the whole country, although proper vaccination programs were applied. In this report, 33 infectious bursal disease viruses (IBDVs) isolated from this outbreak were characterized by nucleotide sequencing of the VP2 gene hypervariable region and were compared with reference IBD strains and the 1990s Spanish IBDVs in order to determine possible emergence of IBDV isolates with modified antigenic or virulent properties. Moreover, histopathologic and immunohistochemical studies of those cases where bursal tissues were available were carried out. Of the 33 isolates, 23 were identified as very virulent IBDVs (vvIBDVs), whereas the other 10 isolates were classified as attenuated or intermediate virulence classical strains and could possibly be IBDV live vaccine strains used in the immunization of these chickens. Results of this study indicate that wIBDV isolates from the 2002 Spanish outbreak are closely related with those from the 1990s outbreak. However, acute IBD cases have not been reported in Spain during these 10 yr. Genetic, management, and environmental factors likely related with IBD reemergence in Spain are discussed. Moreover, our results indicate that good correlation exists between the IBDV subtype present in the field and the degree of lesions in bursa tissue, as well as the immunohistochemistry staining.

Amino Acid Sequence↗

PubMed1994

Outbreaks of contagious ecthyma in camels (Camelus dromedarius) in the Turkana district of Kenya.

Mortality among camel calves (Camelus dromedarius) is one of the most serious problems faced by camel herdsmen and, although there are several reasons for this mortality, diseases play a major role. In an investigation of outbreaks of contagious ecthyma in camels in the Turkana district of Kenya, four outbreaks were detected involving only camel calves. The principal lesions were distinct or largely coalesced pustules on the mouth, nose and muzzle. Direct electron microscopy of infected scabs was used to confirm the presence of the virus. Secondary infection of the pustules was common in affected calves. Morbidity in affected herds was 100%, with no adult involvement. Affected calves were unable to suckle properly. In all outbreaks, there was a concurrent outbreak of contagious pustular dermatitis in goat kids in the same household. Contagious ecthyma is an important disease in camels, contributing to calf debility and eventually to high calf mortality.

Animals↗

PubMed1995

An outbreak of African swine fever in the southern region of Malawi.

An outbreak of African swine fever (ASF) was first detected in December 1989 in the southern region of Malawi. During 1990 the outbreak reached epidemic proportions: by August 1990, over 31,000 pigs (45%) from a population of 70,000 in the affected areas had died or been slaughtered. In affected villages this accounted for 83% of the pigs present. The outbreak probably originated in the central region of Malawi, where ASF is enzootic. Virus isolates from the southern and central region outbreaks in 1989-1990 were indistinguishable using DNA restriction fragment pattern analysis. The rapid spread of the disease and the difficulty experienced in halting this spread are discussed. Important factors included the type of pig husbandry (mainly scavenging without penning) and the fact that veterinary field staff lacked the mobility to ensure the observance of restrictions. New initiatives will be required--in particular, raising public awareness and developing community participation--if ASF is to be controlled in the future.

African Swine Fever↗

PubMed2002

How predictable were the outbreaks of foot and mouth disease in Europe in 2001 and is vaccination the answer?

The author raises three important questions on the outbreaks of foot and mouth disease (FMD) in Europe in 2001: were these linked to stopping preventive vaccination, could these outbreaks have been forecast and were they avoidable, and is vaccination an efficient tool to control outbreaks? The replies to these questions are based on recent history of FMD in Europe. The author demonstrates that the 2001 outbreaks were not linked to ceasing vaccination in Europe in 1991. He also attempts to understand the reasons which encouraged the United Kingdom not to use vaccination to halt the progression of the disease, despite the clear demonstration that vaccination is a useful tool in arresting the spread of an epidemic. In conclusion, the author suggests that substantial changes to European policy for FMD control used for the past ten years are not necessary, but that recourse to emergency vaccination should be considered as an important control option in the future. This option should be optimised by ensuring that differential serological tests are performed in parallel with emergency vaccination, thereby enabling the identification and subsequent elimination of infected herds.

Animals↗

PubMed1977

A large outbreak of foodborne salmonellosis on the Navajo Nation Indian Reservation, epidemiology and secondary transmission.

In September 1974, the largest outbreak of foodborne salmonellosis ever reported to the Center for Disease Control--affecting an estimated 3,400 persons--occurred on the Navajo Nation Indian Reservation. The responsible agent was Salmonella newport and the vehicle of transmission was potato salad served to an estimated 11,000 persons at a free barbecue. The cooked ingredients of the potato salad had been stored for up to 16 hours at improper holding temperatures. The magnitude of the outbreak allowed us to study secondary transmission by calculating the rates of diarrheal illness during the 2 weeks following the outbreak in persons who did not attend the barbecue and by examining the results of stool cultures obtained after the outbreak. We found no secondary transmission. We conclude that a health official should monitor food preparation and service at large social gatherings and that person-to-person transmission of salmonellosis probably does not normally occur even in settings considered highly conductive to cross-infection.

Adolescent↗

PubMed1983

Serologic investigation of an outbreak of hepatitis A in a rural day-care center.

We studied an outbreak of hepatitis A in a day-care center in a rural community where less than 7 per cent of the population possessed anti-HAV. Serotesting for IgM specific antibody to hepatitis A virus identified 78 cases in center attendees, staff, and families. Thirty-five per cent of the center children were seropositive. In children under age three anicteric infection was at least 17 times more frequent than icteric infection, but in older children and adults icterus was a predominant manifestation of the disease. Clinical suspicion should be high in any day-care child with nausea, emesis, diarrhea, or arthralgia. The low incidence of icterus in infected children suggested that outbreak reports reaching public health departments are likely to be incomplete and poorly indicative of outbreak magnitude. The high frequency of intrafamilial transmission and anicteric infection appeared to justify administration of immune serum globulin to household contacts of center children under age three when a day-care outbreak is detected.

Antibodies, Viral↗

PubMed1983

Traveler's diarrhea at sea: two multi-pathogen outbreaks caused by food eaten on shore visits.

In 1976 and 1981, two outbreaks of gastrointestinal illness aboard cruise ships occurred within 24 hours following onshore visits to Haiti and Mexico, respectively. Three hundred eighty-six of 600 (64 per cent) and 98 of 260 (38 per cent) passengers became ill following luncheons in Port-au-Prince, Haiti, and Cozumel, Mexico. No increase in illness was observed among those passengers who did not attend the onshore luncheons. In both outbreaks, unrefrigerated seafood dishes served at outdoor buffets were epidemiologically incriminated as the vehicles of transmission. Several species of Vibrion, Salmonella, and toxigenic Escherichia coli were recovered from stool specimens of ill passengers in both outbreaks. In addition, invasive Escherichia coli and Shigella were isolated from stool specimens of ill passengers who ate at the Haitian buffet. Previous investigations of outbreaks of gastrointestinal illness aboard cruise ships have implicated exposures on board as the source and have involved only a single pathogen.

Diarrhea↗

PubMed1985

Two successive outbreaks of Clostridium perfringens at a state correctional institution.

An outbreak of acute gastrointestinal illness of short duration involving 100 inmates at a correctional institution followed a similar outbreak among the same population by eight days. Clostridium perfringens was the specific etiology in both outbreaks; the vehicle was roast beef in the first outbreak, ham in the second. Direct observation of food handling practices revealed that the meats were not cooled quickly enough following cooking; not reheated adequately prior to serving, and; held at improper temperatures prior to serving.

Animals↗

PubMed1987

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.

Adolescent↗