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Results for “secondary attack rate”

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At least 19 recordsLinked to original sources

PubMed1992

Sex differences in secondary attack rate of IDDM to siblings of probands through older ages. Pittsburgh Etiology of IDDM Study.

OBJECTIVE: To determine the descriptive epidemiological patterns of the secondary attack rate of insulin-dependent diabetes mellitus (IDDM) among siblings of probands through older ages. RESEARCH DESIGN AND METHODS: A family history analysis was performed on 1774 IDDM probands who were diagnosed or seen within 1 yr of diagnosis at Children's Hospital of Pittsburgh from 1 January 1950 through 31 December 1981. The probands were discharged on insulin and were diagnosed at less than 17 yr of age. The time frame permitted the risk of IDDM for siblings of probands to be calculated over a broad spectrum of age. RESULTS: Risk estimates for the 3966 full natural siblings through 10, 20, and 30 yr of age were 1.6, 4.1, and 6.3%, respectively. Secondary attack rates were equivalent for male and female siblings through 15 yr of age (3%); however, the risk to males increased an additional 4% between 16 and 30 yr of age compared with 2.5% for females (P = 0.01). There was no evidence of an excess sex concordance among affected sibling pairs. CONCLUSIONS: Males have a greater secondary attack rate of IDDM at older ages than females. This may be due to an increased exposure to environmental agents among males or protective influences operating among females.

Adolescent↗

PubMed1977

Measles vaccine efficacy determined from secondary attack rates during a severe epidemic.

In February, March, and April 1974, a severe epidemic of measles, with 71 cases and three deaths, occurred on the Cheyenne and Standing Rock Sioux Indian Reservations in South and North Dakota. The attack rate was 9.0 cases per 1,000 persons, and associated with the illness were 24 cases of pneumonia and ten cases of otitis media. Age-specific attack rates were highest in those under one year of age. Using secondary attack rates in persons under nine years of age who were vaccinated and unvaccinated family contacts of cases, vaccine efficacy was measured as 97.3% (95% confidence interval 80.1 to 99.9%).

Adolescent↗

PubMed1976

Meningococcal disease. Secondary attack rate and chemoprophylaxis in the United States, 1974.

Three hundred twenty-six reported cases of meningococcal disease in the United States from November 1973 through March 1974 were investigated. Three household members became ill with meningococcal disease following onset of the initial case in their household. The secondary attack rate was approximately 3/1,000 household members. In 60% of the households, members were given an antimicrobial drug as chemoprophylaxis for meningococcal disease, but only 35% received minocycline hydrochloride or rifampin, the two drugs now available for the eradication of sulfonamide-resistant meningococci from the nasopharynx. Only 26% given chemoprophylaxis received the drug within 24 hours after the patient's hospital admission. Survey results indicate that the secondary attack rate of meningococcal disease may justify the use of chemoprophylaxis, but that frequently in the United States, the drugs given are likely to be ineffective, give too late, or administered to persons who are not at high risk to meningococcal disease.

Adolescent↗

PubMed1979

Common exposure outbreak of gastroenteritis due to type 2 rotavirus with high secondary attack rate within families.

A sharp outbreak of gastroenteritis associated with human rotavirus type 2 involved not only all of nine infants and young children in a playgroup but also seven of 10 parents and grandparents studied. The source of the outbreak appeared to be two non-playgroup siblings. Six of 11 individuals studied shed human rotavirus type 2, and each of seven from whom paired sera were obtained developed a type 2 sero-response. Overall, evidence of infection with rotavirus type 2 was demonstrated in 10 of 11 individuals by detection of virus in stools and/or a serologic response in an enzyme-linked immunosorbent assay.

Antibodies, Viral↗

PubMed1977

Contagiousness of acute hepatitis B. Secondary attack rates in household contacts.

In order to define the hazard of household exposure to patients with acute hepatitis B, in the absence of persistent hepatitis B surface antigen (HBSAg), 98 household contacts of 42 patients with the acute disease were interviewed and tested for HBSAg, antibody to HBSAg (anti-HBS), and serum transaminases shortly after identification and at 3-month intervals for at least 12 months. Most of the index cases with acute hepatitis B were young men and many had used illicit drugs parenterally before the onset of illness. Three of the household contacts had HBSAg detected on initial testing, and 2 of these were carriers with elevated serum transaminase levels. The 3rd HBSAg-positive contact developed acute hepatitis within 2 weeks. This appeared to represent a coprimary infection. Fourteen contacts had anti-HBS on initial evaluation and were considered immune as a result of prior experience with hepatitis B. Of 81 susceptible contacts (neither HBSAg nor anti-HBS on initial screening), 13 were spouses or sexual partners and 2 of these developed acute hepatitis B at 4 and 6 months after the onset of illness in their respective index cases; another developed anti-HBS at 6 months. Thus, 3 (23%) of 13 exposed spouses or sexual partners developed evidence of hepatitis B infection during the surveillance period. In contrast, no evidence of hepatitis B infection related to household exposure was found in 68 parents, siblings, and other domestic contacts. These data confirm the contagiousness of hepatitis B for household contacts of acute cases and suggest that the risk is confined to spouses and sexual partners. These persons appear to be prime candidates for prophylaxis with hepatitis B immune globulin.

Acute Disease↗

PubMed1978

Spread of Haemophilus influenzae. Secondary illness in household contacts of patients with H influenzae meningitis.

To determine the risk of severe secondary illness in household contacts of patients with Haemophilus influenzae meningitis, telephone interviews were conducted with contacts of patients with reported cases. Four probable or proved secondary cases of severe disease were identified for a secondary attack rate of 0.4%. The secondary attack rate for household contacts of patients 2 years of age and younger was 4.9%. Until safe, effective prophylactic measures become available, physicians should explain to parents that any person who becomes ill in the month after a household case of H influenzae meningitis should be brought to the attention of a physician for appropriate evaluation and treatment.

Child, Preschool↗

PubMedDate not supplied

Transmission of leprosy within households.

As part of the leprosy control program, population follow-up studies were carried out during 1962 to 1970 in Gudiyatham Taluk, an administrative unit in South India (population: 400,000). More than 97% of the 23,285 contacts from 5,088 families having a leprosy patient were clinically examined using accepted methodology and confirmed as having or not having leprosy. New cases developing among household contacts of leprosy (secondary attack rates) were determined and studied in relation to characteristics of the index case and that of contacts. The secondary attack rate is defined as the number of new cases discovered in the contacts of leprosy patients per 1,000 person-years, which is equivalent to observing 1,000 persons per year. Nearly two-thirds of all new cases were of the tuberculoid type of leprosy and another one-sixth of indeterminate type. Lepromatous and borderline cases each constituted about ten percent of the total new cases. The total secondary attack rate was 6.8 per 1,000 person-years. Compared to an annual incidence rate of 0.8 per 1,000 in the total population, this incidence rate among the contacts is nearly ten times higher. Such enhanced risks are observed clearly and consistently when studied by the number of patients within a family for both sexes and in various age-groups. The rate for females (6.3 per 1,000 person-year) though less, was not significantly different from that of males (7.1 per 1,000 person-year). The differences observed between males and females for each type of leprosy were also not statistically significant. The risks for children (less than 15 years) are significantly higher than those for adults. Among boys, the maximum risk was observed in the age-group 5-14 years, whereas for females the risk is highest in the age-group 5-9 years, dropping down significantly after that. Furthermore, it was observed that significant differences existed between children and adults only in males but not in females. The secondary attack rates almost doubled when there were multiple index cases in the family. Regardless of the number of index cases, the male-female differences were not statistically significant. Attack rates were significantly enhanced when there was a bacilliferous type of leprosy (lepromatous or borderline) in the family. This was true for the specific attack rates of each type of leprosy too. However, a significantly higher proportion of lepromatous and borderline types is also seen when there is a bacilliferous type of leprosy present. The study reiterates the differences in susceptibility to leprosy among males and females, especially during younger ages. Further immunological studies are necessary to determine the differences in host responses in males and females that produce such a characteristic sex-ratio in prevalence of leprosy. There is still a great need to obtain more data on incidence rates both in general population and among contacts on the basis of prospective observation using acceptable statistical technics in design and analysis.

Adolescent↗

PubMed1975

Epidemic keratoconjunctivitis: a community outbreak of mixed adenovirus type 8 and type 19 infection.

During the fall and winter of 1973, 145 cases of epidemic keratoconjunctivitis were diagnosed in Nashville, Tennessee. Of the 74 cases studied virologically and/or serologically, 62% were caused by adenovirus type 8, and 28% were caused by adenovirus 19. Whereas adenovirus type 8 was isolated only from conjunctival scrapings, adenovirus type 19 was isolated from nose and throat swabs as well as from conjunctivae. The two viruses produced clinically indistinguishable eye disease and household secondary attack rates that were not statistically different. Regardless of etiology, the secondary attack rate in households was significantly higher among the contacts of those patients who had severe disease for greater than 28 days than among the contacts of patients who had milder disease of shorter duration.

Adenoviridae↗

PubMed2026

Association of Baloxavir Treatment Timing with Serial Interval and Household Transmission of Influenza through a Likelihood-Based Analysis.

BACKGROUND: Baloxavir treatment is associated with reduced influenza transmission within households, and the serial interval varies by treatment status. However, it remains unclear how baloxavir-induced changes in the serial interval relate to household transmission. We aimed to quantify the model-based association between baloxavir treatment timing and the serial interval and household transmission risk. METHODS: We conducted a household survey of influenza cases in Japan between October 2018 and February 2019. We defined the likelihood-based model integrating the serial interval distribution by treatment status and the secondary attack rate (SAR) using individual-level data from index cases. Using this model, we estimated the reduction in the serial interval associated with baloxavir treatment. RESULTS: Compared with untreated index cases, baloxavir-treated cases were estimated to have a serial interval density reduced by 21.42% following treatment. Treatment within 24 hours was associated with a 0.1685 reduction in the area under the curve, with smaller reductions as treatment was delayed. Earlier treatment was associated with a shorter, more concentrated distribution, whereas treatment 72 hours after onset resembled untreated cases. CONCLUSIONS: Our findings highlight that baloxavir treatment is associated with a shorter serial interval and lower estimated secondary household transmission risk. We provide model-based estimates suggesting that earlier administration is associated with a greater reduction in serial interval density and estimated transmission risk, which may inform public health strategies for infection control.

Influenza↗

PubMed1978

An intercity outbreak of meningococcal meningitis in adults.

An intercity outbreak of meningococcal meningitis occurred in five adults, with the acute onset of symptoms developing in two of the patients after they returned to Los Angeles from the San Francisco Bay area. The secondary attack rate was 36.4 percent in this entirely adult household. The authors review reports of secondary cases in civilian epidemics, as well as recommendations for chemoprophylaxis in household contacts.

Adolescent↗

PubMed1976

Respiratory syncytial virus infections within families.

To examine intrafamily spread of respiratory syncytial virus infections and their associated illnesses, 36 families with 188 members were studied during an outbreak of such infections. Nurses visited every three to four days to obtain specimens for viral isolation and interview household members. The virus infected 44.4 per cent of families, and 21.9 per cent of all members. All age groups had appreciable attack rates (with a range of 16.8 per cent in adults to 29.4 per cent in infants). In infected families, 45.9 per cent of members became infected, including 10 of 16 infants. Secondary attack rate for all ages was 27 per cent, and that for infants 45.4 per cent. An infant's older sibling appeared most likely to introduce the virus into the family. Associated acute respiratory illnesses occurred in 94.9 per cent of cases, and appeared more severe than those not associated with respiratory syncytial virus. When the virus was introduced into a family the high attack rate produced an illness of age-related severity.

Adolescent↗

PubMed1992

Clusters of meningococcal disease in France (1987-1988).

We analyzed 814 cases of meningococcal disease notified in 1987 and 1988 to the Ministry of Health. Data were obtained by report forms including informations about possible additional cases among contacts. Coprimary cases (occurring within 24 hours after the index case) and secondary cases (occurring more than 24 hours after index case) were all reviewed. Twenty eight clusters of meningococcal disease were identified involving 65 cases (8% of total cases). Twelve of the 814 cases (1.5%) were coprimary cases of an index case and 25 (3%) were secondary cases. The secondary attack rate was 530/100,000 among household contacts and 31/100,000 among school contacts. Seventy two per cent of the secondary cases occurred in the first week after index case. Thirty-eight percent of the secondary cases occurred in the 15-20 age group as opposed to 15% of single cases. Serogroup A was more often found in coprimary (33%) and secondary cases (17%) than in single cases (6%). In France, prophylaxis of secondary cases is administered to the classroom contacts of a case of meningococcal infection but is not required for the entire school except under epidemic conditions.

Adolescent↗

PubMed1979

Variola minor in Braganca Paulista County, 1956: household aggregation of the disease and the influence of household size on the attack rate.

Household aggregation of cases, one possible characteristic of person-to-person transmitted disease, was formally tested in one epidemic of variola minor by using a pair statistic. A significant result was found for all households as well as for households grouped by the type of environment, or by the phase of the epidemic growth in time. Secondary attack rates, when related to household size (number of susceptibles) showed only a marginal trend in rural households but no trend in urban or semi-rural households.

Brazil↗

PubMed1975

Public health considerations in the management of meningococcal disease.

We discuss chemoprophylaxis of household contacts of cases, the current status and use of meningococcal vaccine, and the role of surveillance of household contacts. Available data on secondary attack rates strongly support the need for chemoprophylaxis of household contacts of meningococcal disease cases. Until the current difficulties with side reactions to minocycline are resolved, we recommend the use of rifampin. Surveillance of household contacts alone is an untested, generally impractical, and probably ineffective method of preventing secondary cases of meningococcal disease, although it may have some effect in preventing death by encouraging prompt and appropriate treatment of cases. We recommend the use of serogroups A or C vaccine, or both, in populations experiencing an epidemic of serogroups A or C meningococcal disease. The use of serogroups A or C meningococcal polysaccharide vaccines should also be considered, along with chemoprophylaxis for household contacts of sporadic cases due to either of these organisms.

Anti-Bacterial Agents↗

PubMed1975

The Seattle Virus Watch. VI. Observations of infections with and illness due to parainfluenza, mumps and respiratory syncytial viruses and Mycoplasma pneumoniae.

Seattle Virus Watch families were observed, 1965-1969, for infections with paramyxoviruses and M. pneumoniae by agent isolation and antibody assay of serial sera. Infection rates, based on serology, exceeded those in Tecumseh where families contained fewer young children. Rates per 100 person-years were 44.4 for parainfluenzavirus, 21.6 for respiratory syncytial (RS) virus and 12.3 for M. pneumoniae. Preschool children experienced the highest rates for RS and parainfluenza-viruses but, for the latter, rates were also high among older children and adults. Within invaded families infection rates generally varied inversely with age, although for M. pneumoniae the rates for adults and 6-9 year old children nearly equalled the infant rate. The introducers' identity and/or the age-specific infection rates in invaded families support the role of young schoolchildren in community spread of M. pneumoniae and, together with older children and adults, of RS virus. Young schoolchildren were less important than infants, preschoolers, and adults in spreading parainfluenza-viruses and less important than preschoolers and infants for mumps. The frequent infection of exposed older children and adults suggests that reinfection with all the agents studied is common. All agents spread significantly within families and secondary attack rates for the mostly non-immune infants indicated high infectivity of parainfluenza and mumps viruses. The basic high pathogenicity of these agents and of RS virus is indicated by the high frequency of illness among virus shedders (80-90%) and among seroconverting infants (greater than or equal 68%). The less frequent illness of older persons with serologically proven infection is consistent with diminished clinical response to reinfection. Parainfluenza-associated illnesses were relatively severe and contributed up to 9.3% to total respiratory illnesses. RS virus-related illnesses also were severe but contributed less (4-5%) to total respiratory disease. Mumps-associated illness was largely respiratory, 65% overall, 77% in infected infants and 75% above age 9. Thus, mumps virus emerges as another respiratory pathogen which is spread largely by 2-5-year old children rather than by schoolchildren with "typical" parotitis.

Adolescent↗

PubMed1978

A study of acute respiratory disease in the community of Port Chalmers. II. Influenza A/Port Chalmers/1/73: intrafamilial spread and the effect of antibodies to the surface antigens.

During the first year of a study of respiratory disease in the semi-isolated community of Port Chalmers, New Zealand, an epidemic of clinical influenza occurred from which the variant influenza A/Port Chalmers/1/73 (H3N2) was isolated. Within a selected group of 26 families, 59 (46%) members had clinical or laboratory evidence of infection. During intrafamilial spread the infection frequency was highest for school-aged children (77%), followed by female adults (67%), infants (64%) and male adults (41%). The index infection in each family was a school-age child on 10 occasions, suggesting the role of this age group in the transmission of influenza A in this community. The secondary attack rate (SAR) of 58.3% was higher than expected. In sera taken before the 1973 epidemic, 59% of family members had detectable HI antibody and 25% NI antibody to A/England/42/72 while 38% had detectable HI antibody and 8% NI antibody to A/Port Chalmers/1/73. The relation between pre-existing antibody and infection frequency is discussed.

Adolescent↗

PubMed1975

The Seattle virus watch. V. Epidemiologic observations of rhinovirus infections, 1965-1969, in families with young children.

Rhinovirus (RV) infections in Seattle Virus Watch (VW) families (1965-1969) were monitored by screening respiratory specimens in WI-38 cell cultures and by homotypic neutralization tests on sera related to family episodes revealed by RV isolation. Temporally related illness in members not proven infected was also taken to indicate infection. RV isolates (including those from the New York VW, 1961-1965) were typed within the official 90-serotype frame. Typed isolates from New York (165 with 39 serotypes) and Seattle (456 with 59 serotypes) were compared with the Tecumseh Study to test the hypothesis that some serotypes are "common," persisting because of greater infectivity. Of 32 serotypes qualifying as "common" in at least 1 study, 4 were "common" in all 3 studies and 8 in 2 studies. The 23 "common" Seattle serotypes differed from the remaining 36 serotypes in being more infective and in their more frequent association with prolonged shedding. The New York and Seattle isolates together revealed an increase over time in the proportion not typable or of of higher numbered types, consistent with progressive shift in RV antigenic character. WI-38 isolates indicated spring peaks of RV all 4 years but a fall peak only in 1967. An even larger fall peak was seen when all specimens from September-November 1968 were re-examined in fetal tonsil diploid cells. Thus, both spring and fall peaks appear to describe RV seasonality. RV infections explained 16% of all reported respiratory illness (20% of upper respiratory), but RV-associated illness in young children, especially under 2 years, was more severe and almost twice as frequent as in adults. The age of introducers and the direct relation of family size to frequency of episodes indicate that community spread depends largely on preschool children, including infants. Within families, the secondary attack rate (SAR) was highest following paternal introduction and, for all introducers, the SAR varied inversely with age (mother excepted). RV shedding was observed most often (85% of specimens) from the day before to 6 days after illness onset but prolonged shedding was common (to 21 days in 20% and 28 days in 1.4% of infections). RV infectivity, reflected by SAR among nonimmunes, was highest for infants (78%) and, for all ages, was greater with ill than with well introducers (71% versus 27%). Immunogenicity of RV was poor (Seroresponse: 48% of shedders, 32% of nonshedding contacts) but varied greatly with serotype. Illness frequencies among non-immunes were 59% for all proven infections and 35% when infection was not shown..

Adult↗

PubMed1976

Three tests for randomness of attack of social groups during an epidemic.

It is suggested that investigation of the attack of social units can be more illuminating of an epidemic process than the usual study of secondary attack rates of individuals. Three tests for detecting non-random differences in the occurrence of a disease between two groups of social units are presented. In each method the number of units attacked (X) in one of two groups of units is considered, rather than the number of individuals attacked. The tests are: (a) to use the Monte Carlo method, computer simulation of the epidemic process, to obtain an empirical distribution to which the observed value of X is compared; (b) to obtain the exact distribution of X; (c) to standardize X and compare it to the standard normal distribution. The three approaches are compared using data obtained from an epidemic of variola minor in two schools and the differences between the results are trivial. However, for large samples the only feasible approach is the Monte Carlo method.

Brazil↗