Because of the different standard and quality of health service system among Thailand and its
3 neighboring countries, many migrants carries contagious diseases that were already controlled in
Thailand. Pulmonary Tuberculosis, Syphilis, Leprosy, Malaria and Elephantiasis were the 5 most
common contagions/communicable diseases. The Diarrhea, Influenza, Dengue hemorrhagic fever
were more difficult to eradicate among the undocumented migrants in the urban area. These diseases
can also spread into Thai people by many vectors and routes in the tropical climate. The sanitation
and environment of the migrant’s communities are poor and because of the un-registration housing,
due to the fact that these illegal immigrants are inapplicable to services from local authorities.