5.2.2 Yersinia Yersinia is a genus of heterotrophic bacteria with 11 recognized species, some of which cause disease in humans, and both pathogenic and non-pathogenic strains of Yersinia have been found in surface water and unchlorinated drinking-water (Lassen 1972; Caprioli et al. 1978; Cafferkey et al. 1993)..2.2 Yersinia Yersinia is a genus of heterotrophic bacteria with 11 recognized species, some of which cause disease in humans, and both pathogenic and non-pathogenic strains of Yersinia have been found in surface water and unchlorinated drinking-water (Lassen 1972; Caprioli et al. 1978; Cafferkey et al. 1993).
1 When a woman ovulates, the egg is able to be fertilized for 12-24 hours (1 day). 2  When sperm enters the woman's body, it remains alive and able to fertilize an egg for 1-5 days. 3  It takes emergency contraception from 12-24 hours to be effective (1 day).  Emergency contraception remains effective for at least 10 days.
Your periods may be irregular when you first come off the pill, and you should allow up to three months for your natural menstrual cycle to re-establish itself fully. This is because the pill contains the hormones that stop ovulation (the release of an egg) each month. The first period after stopping the pill is known as a withdrawal bleed. The next period after this withdrawal bleed is your first natural period.