Dengue fever and chikungunya are both mosquito-borne infections for which no vaccines are available. The HPA advises travellers to ensure they take necessary precautions against mosquito bites when visiting endemic areas.
Cases of dengue fever and chikungunya are not actively monitored by the HPA, so data are sent in by diagnosing clinicians when they submit cases for laboratory confirmation.
From 2009 to 2010, cases of dengue fever imported into the UK rose from 166 to 406. Cases occurred most commonly among people in their 20s and were most commonly reported in travellers returning from India, Thailand and Indonesia.
The HPA said it was not clear why cases from India had risen as indigenous cases reported in India and visits by UK residents to India both fell in 2010 compared with 2009.
For chikungunya, cases rose from 63 in 2009 to 79 in 2010 and occurred most often in those aged 45 to 49.
Individuals diagnosed with chikungunya had most often travelled to India.
In fact, compared with 2009, there was a two-fold increase in cases from India, a difference not accounted for by UK travel trends.
Last month, the HPA released data showing that malaria infections had increased by 30 per cent since 2008, rising to 1,761 cases in 2010. In 85 per cent of cases, patients had not taken any antimalaria drugs.