Background In resource-limited settings, where rubella is endemic, it is difficult to determine which sporadic case should be tested for rubella. The study aimed to provide useful evidence to help screen rubella cases for real-time reverse transcriptase-polymerase chain reaction (RT-PCR) examination for rubella in resource-limited settings. Method Suspected rubella patients identified by a physician and brought to the notice of the Ryugasaki public health center or the Tsuchiura public health center were enrolled from April 2018 through December 2019. The inclusion criterion was a confirmed rubella diagnosis based on laboratory tests. We studied the distribution of the time from the onset of fever until the onset of rash. Results The study included 86 cases with simultaneous presentation of fever and rash. Twenty-nine cases had confirmed rubella based on the laboratory diagnosis. Among these, the time from the onset of fever until the onset of rash was limited to − 1 day to 2 days. The number of rubella cases was the highest when the onset of rash was on the following day of the onset of fever. Of the 78 patients who underwent the RT-PCR test, 48% tested positive for rubella among those with a time from the onset of fever to the onset of rash between − 1 day and 2 days (22 out of 46, 95% confidence interval 34–62%); no positive results (0 out of 30, 95% confidence interval - 14%) were seen in patients with a time from fever to rash onset ≥3 days. Conclusion The period from the onset of fever to the onset of rash was limited to − 1 day to 2 days among confirmed rubella patients. If the period from onset of fever to the onset of rash was ≥3 days for a patient, the likelihood of rubella was low.

In recent years, drug-induced photosensitivity as a side effect has been an increasing problem. To examine the effectiveness of broadspectrum sunscreens in preventing the disease, we quantitatively assessed efficiency of some sunscreens in suppressing the photosensitized reactions with sparfloxacin, a fluoroquinolone antibacterial agent. Some broad-spectrum sunscreens suppressed sparfloxacin-photosensitized formation of strand-breakage in plasmid pBR322 DNA. The present findings suggest that the use of broad-spectrum sunscreens contributes to the prevention of drug-induced photosensitivity. In addition, the suppressive effects showed a linear relation with the effective UV-A quanta absorbed by the tested sunscreens independent of the product types and manufacturers. Therefore, we propose that the indication of UV-A absorption spectrum in addition to PA classification (protection grade of UV-A) as factors for assessing for the ability of sunscreens to prevent drug-induced photosensitivity. An in vitro method to assess quantitatively the effectiveness of broad-spectrum sunscreens in preventing druginduced photosensitivity was also presented.