A newborn baby and four children were among the 395 people newly diagnosed with HIV last year, it was disclosed today.
Latest figures also showed a 42.2% rise in the number of gay and bisexual men infected in 2009, despite the overall rate dropping slightly.
The Health Protection Surveillance Centre (HPSC) confirmed 138 men who had sex with men (MSM) were diagnosed up to December, compared with 97 the previous year.
Dr Aidan O’Hora specialist in public health medicine, said: “The majority of these men – 63% – were born in Ireland and most likely acquired their infection here.
“Young men under 30 years of age accounted for 35% of new diagnoses.
“This trend is consistent with what is being seen in many other western industrialised countries.”
The HPSC said 1,038 people were living with Aids by the end of December. The figure included 33 who were newly diagnosed throughout the year and two people had died from Aids.
A further 5,637 people were living with HIV.
But Dr O’Hora warned: “The epidemiology of HIV in Ireland is complex and due to the voluntary nature of the reporting system, it is likely that the number of case reports is an underestimate.”
Of those newly diagnosed with HIV:
:: 156 cases were heterosexually acquired, 30 were injecting drug users (IDUs), while the cause was unknown in 65 cases.
:: 258 were men and 137 were women – 13% of whom were pregnant.
:: The average age was 35 years.
:: Five were children who were infected through mother to child transmission (MCT).
:: Where geographic origin was known: 141 were Irish; 96, sub-Saharan African; 21, Western European; 13, Central European; 15, Eastern European; 14, South American.
Tiernan Brady, of the Gay and Lesbian Equality Network (GLEN), said it was clear HIV remained an issue of critical concern for men who have sex with men.
“A renewed focus on prevention of HIV is urgently required with this group of men,” said Mr Brady.
“The reasons for this increase must be better understood so as to reduce this rising incidence of HIV.
“However, if we are to succeed in preventing further infections, we must also tackle the continuing stigma and discrimination associated with HIV.”
Of those who contracted HIV through a heterosexual relationship, 87 cases – 58 female and 29 male – were born in sub-Saharan Africa and 40 cases – 18 female and 22 male – were born in Ireland.
Among gay men, 87 were born in Ireland and 38 were born abroad, while 13 drug users diagnosed were Irish and 14 were born abroad.
Of the five children infected, one was born in Ireland to a mother who was known to be infected during pregnancy and originally from sub-Saharan Africa.
The remaining four were older children who were born in sub-Saharan Africa.
A further 135 babies – including twins – were born to 131 HIV infected mothers, while 13 cases are undetermined and 122 were given the all clear.
Dr O’Hora urged adults to practise safe sex.
“Anyone engaging in sexual activity should practise safe sex. A properly used condom provides effective protection from HIV,” he said.