Loglinear models using capture-recapture methods to estimate the size of a measles epidemic.

Cases of measles reported separately by doctors, hospitals, laboratories, and others are treated as separate captures and releases of the population of children aged up to 10 years who have been infected by measles in a recent epidemic. Loglinear models are used to assess the adequacy of fit of various models for capture-recapture and the size of the epidemic in different age groups is estimated.

Measles outbreak in western Sydney. Vaccine failure or failure to vaccinate?

OBJECTIVES: To determine the effectiveness of measles vaccine during a measles outbreak, and to assess whether age at vaccination was a risk factor for measles vaccine failure. DESIGN: A matched case-control study. SETTING: The five primary schools in western Sydney with the largest number of measles cases during the June to December 1993 outbreak. SUBJECTS: Seventy-nine children aged 5-9 years with an illness consistent with a clinical definition for measles. Two controls per case were selected from children in the same classroom. MAIN OUTCOME MEASURES: Estimated measles vaccine effectiveness by age of the child at vaccination and vaccination status: "unvaccinated"; "parental recall" (parents stated the child was vaccinated but no record could be found); and "record" (record including date of vaccination available). RESULTS: The estimated vaccine effectiveness was 94% (95% confidence interval [CI], 83%-98%) in the "record" group, and 81% (95% CI, 46%-93%) in the "parental recall" group. Vaccine effectiveness did not differ significantly with age at vaccination (under 12 months of age 96% [64%-99%]; 12-14 months 95% [81%-99%]; and 15 months and over 93% [80%-98%]). CONCLUSION: Vaccination records should be used to calculate a vaccine's effectiveness as parental recall may not be sufficiently accurate. The high vaccine effectiveness in the "record" group (94%) makes it unlikely that low vaccine effectiveness was the cause of the outbreak. More effort is needed to increase vaccine coverage to at least 95% in all population subgroups.

Activity of gonadotropin-releasing hormone neurons during the preovulatory luteinizing hormone surge.

We assessed the frequency of luteinizing hormone (LH) pulsatility (reflecting the activity of gonadotropin-releasing hormone [GnRH] neurons in the hypothalamus) in six women during the periovulatory LH surge, in five women during the early follicular phase, and in seven women in the midfollicular phase (MFP) (calculated as being 3 to 8 days before the LH surge). Collection of blood at 5-minute, versus 15-minute, intervals allowed detection of a larger number of LH pulses in both the MFP (16, versus 27) and periovulatory phase (POP) (11, versus 22) groups of women, but it made no difference in the early follicular phase (EFP) (10 pulses with both methods). During the EFP, the mean number of LH pulses per 4 hours (detected by 5-minute sampling) was 2.0 +/- 0.7 (+/- standard deviation [SD]), and the mean LH amplitude (+/- SD) was 1.3 +/- 0.4 IU/l. There was a significant increase in the number of pulses in the MFP group (3.9 +/- 1.3 pulses/4 hours; P less than 0.05) but no significant change in pulse amplitude (1.1 +/- 0.1 IU/l). During the POP, the mean pulse amplitude was increased (8.5 +/- 1.4 IU/l; P less than 0.001), compared with the MFP and EFP groups, but the mean pulse frequency (3.7 +/- 1.2 pulses/4 hours) was not significantly different from the MFP frequency. We conclude that an acceleration of LH pulsatility occurs several days before the LH surge and does not change thereafter. However, there is an increase in LH pulse amplitude during the LH surge; we attribute this to the increase in pituitary sensitivity at this time.(ABSTRACT TRUNCATED AT 250 WORDS)