HEALTH ADVICE from the Foreign and Commonwealth Office website FCO.gov.uk
In 2005 there were reports of a small number of tourists contracting malaria in the La Altagracia province in the east of the country. In the majority of cases the visitors were staying in the Bavaro and Punta Cana resorts. The resort of Bayahibe is also within the same province. Before travelling, you are advised to contact your doctor for up-to-date advice on anti-malarial medication and on arrival, ensure that you take adequate precautions against being bitten by mosquitoes. More than three-quarters of British travellers who contracted malaria in 2005 did not take preventive measures, such as malaria prevention tablets. However, malaria can occur despite appropriate prevention, and therefore you should promptly seek medical care in the event of a fever or flu-like illness in the first year following your return from travelling to a malaria risk country. Before travelling you should seek medical advice about the malaria risk in the Dominican Republic.
There is also a year round threat from dengue fever, which is contracted from mosquitoes. The highest number of cases usually reported in the hot season from May to November. Recent media reports indicate an increased incidence of this disease in the cities of Santo Domingo and Santiago but cases have been reported throughout the country. There is no vaccine to protect against dengue fever and you should therefore use mosquito repellent regularly and cover up with suitable clothing to avoid being bitten. Symptoms of dengue fever usually begin seven to ten days after being bitten and include fever with aching joints and bones and a headache.
Rabies exists so steer clear of stray dogs and cats.
Don't drink tap water or buy food from street vendors.
High prevalence of the HIV/AIDS virus in the Dominican Republic, take precautions to avoid exposure to it.