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.
3. The pill is to be taken soon after unprotected sex. It should be taken preferably within 24 hours and before 72 hours or else the pill may turn useless. 4. I-pill checks pregnancy by preventing ovulation or fertilisation or implantation of the fertilised egg. 5. I-pill is 95 per cent effective if taken in time.