We get malaria prevdoxycycline100mg 1tab daily.do i have to take it up to 4weeks after leaving this place or just 4weeksbecause already 2weeks in port?

4 weeks once no risk: Regarding Doxycycline as a malaria "preventive", you need to complete 4 weeks of daily therapy once you've left the area of malaria risk (eg: no further risk of being bitten by a possibly infected mosquito). Depending on where you are, you likely need to continue for four more weeks as there is likely risk in your port. If not, then you only need to finish up the remaining two weeks.

Be Careful: For malaria prevention, Doxycycline must be continued a full four weeks after leaving a malaria zone.Whenever that time begins, count a full four weeks and do not skimp. Shortchanging any doses of Doxycycline can lead to a late case of malaria.