Migrants make up about 70% of TB, HIV and malaria cases in England, Wales and Northern Ireland, a report has found.
The report said migrants were more likely to have HIV, TB or malaria
The Health Protection Agency said this was a "disproportionate burden", but stressed it reflected a small fraction of people not born in the UK.
In its first report on migrant health, it also found there was little evidence to suggest the general population was being placed at increased risk.
The Department of Health said the report would be a "valuable tool".
Recent government figures estimated about 1,500 migrants arrived every day to live in the UK in 2005.
In 2001, the report said, 7.53% of people living in the British Isles were migrants, the majority coming from Europe, South Asia and Africa.
Dr Jane Jones, of the Health Protection Agency, said: "The majority of TB, HIV and malaria cases were found in people not born in the UK."
But she added: "This must be seen in context: most migrants do not have these diseases."
She said the reason migrants were more likely to carry these diseases was because they came from parts of the world where the infections were more common, and had either been infected before they came to the UK, or infected on visits to their country of origin.
The HPA report added the migrants may have also contracted diseases after they had arrived in the UK, because of close contact with other migrants or travel.
But it said evidence revealed the general UK population was not at increased risk of TB, HIV or malaria infection from migrants, but some UK-born ethnic communities did have a higher risk of disease because of their links to countries where the diseases were endemic.
The HPA has put forward a range of recommendations to improve migrant health, including increased diseases surveillance, primary care support, such as language and cultural support, and raising awareness.
But Professor Pat Troop, chief executive of the HPA, said the agency was waiting for more evidence to see if screening of migrants on arrival would be an effective measure.
A Department of Health spokesperson said: "The data in this report will be a valuable tool for NHS Trusts in planning their services to meet the needs of different migrant groups."
Yusef Azad, director of policy and campaigns at the National AIDS Trust, said: "This important report makes clear how untrue it is to claim migrants pose any health risk to the UK population - indeed the rates of infectious disease are low.
"But it is also clear that there are real health needs in this group of people, including around HIV. The government must look again at all its immigration processes in the light of this report to ensure they promote rather than undermine the health of migrants in the UK."