Although Colombia is a very welcoming country, there is a list of countries whose citizens are required to have a visa to enter our country (see http://www.colombia.travel/en/practical-information/visa or attached document page 11 -in spanish- ).
Is important to verify if your country is in the list of the countries (see page 17 in the attached document -in spanish- ) which for entering Colombia need the Yellow Fever Vaccine.
Please verify whether you require a Colombian visa or not. Upon arrival, foreign participants should ask for the PIP-6 stamp at the immigration stand, which identifies them as participants of a scientific event (as opposed to tourists). This is VERY IMPORTANT for the local organization.