18 December 1922, and entered into effect on 15 February 1923. Another one was signed between the governments of Poland and Romania on 20 December 1922. Ratifications were exchanged on 11 July 1923. The Polish government also concluded such a convention with the Soviet government on 7 February 1923, for which ratifications were exchanged on 8 January 1924. A sanitary convention was also concluded between the governments of Poland and Czechoslovakia on 5 September 1925, for which ratifications were exchanged on 22 October 1926. A convention was signed between the governments of Germany and Latvia on 9 July 1926, for which ratifications were exchanged on 6 July 1927. In 1897, the incubation period for this disease was determined and this was to be adopted for administrative purposes. The incubation period was comparatively short, some three or four days. After much discussion ten days was accepted by a majority. The principle of disease notification was unanimously adopted. Each government had to notify other governments of the existence of plague within their jurisdictions and state the measures of prevention being carried out to prevent its spread. The area declared infected was limited to the district or village where the disease prevailed, and no locality was deemed to be infected because of the importation into it of a few cases of plague while there has been no spread. It was decided during the prevalence of plague, every country had the right to close its land borders to traffic. At the Red Sea, it was decided after discussion a healthy vessel could pass through the Suez Canal and continue its voyage in the Mediterranean during the incubation period of the disease and that vessels passing through the Canal in quarantine might, subject to the use of the electric light, coal up in quarantine at Port Said by night or by day, and that passengers might embark in quarantine at that port. Infected vessels, if these carry a doctor and a disinfecting stove, have a right to navigate the Canal in quarantine and subject only to the landing of those who have plague. In the 20th and 21st centuries, people suspected of carrying infectious diseases have been quarantined, as in the cases of Andrew Speaker (multi-drug-resistant tuberculosis, 2007) and Kaci Hickox (Ebola, 2014). During the 1957–58 influenza pandemic and the 1968 flu pandemic, several countries implemented measures to control spread of the disease. In addition,