Article 18U.K.Public health
1.Member States may refuse applications for residence from long-term residents or their family members where the person concerned constitutes a threat to public health.
2.The only diseases that may justify a refusal to allow entry or the right of residence in the territory of the second Member State shall be the diseases as defined by the relevant applicable instruments of the World Health Organisation's and such other infectious or contagious parasite-based diseases as are the subject of protective provisions in relation to nationals in the host country. Member States shall not introduce new more restrictive provisions or practices.
3.Diseases contracted after the first residence permit was issued in the second Member State shall not justify a refusal to renew the permit or expulsion from the territory.
4.A Member State may require a medical examination, for persons to whom this Directive applies, in order to certify that they do not suffer from any of the diseases referred to in paragraph 2. Such medical examinations, which may be free of charge, shall not be performed on a systematic basis.