Home > New data on the incidence of HIV.

Long, Jean (2006) New data on the incidence of HIV. Drugnet Ireland, Issue 19, Autumn 2006, p. 24.

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HIV (subsequently known as HIV1) was identified in 1981 and HIV2 was identified in 1986. The virus attaches itself to the CD4 particle of the T-lymphocytes. These T-lymphocytes co-ordinate the body’s immune response. HIV may lead to a condition known as acquired immunodeficiency syndrome (AIDS). This condition generally occurs when the CD4 count is below 200 per millilitre and is characterised by the appearance of opportunistic infections. Such infections take advantage of a weakened immune system. The HIV virus is found in all body fluids and is transmitted via sexual intercourse (both heterosexual and homosexual), mother to foetus and baby, infected blood and blood products and procedures with unsterile needles, syringes and skin-piercing instruments. Best evidence available to date indicates that once an individual is infected he or she remains infected for life.

Voluntary linked testing for antibodies to HIV has been available in Ireland since 1985. By the end of 2005, there were 4,082 diagnosed HIV cases in Ireland, of which 1,270 (31%) were probably infected through injecting drug use.1

Figure 1 [see PDF document] presents the number of new cases of HIV among injecting drug users, by year of diagnosis, reported in Ireland; data from 1982 to 1985 were excluded from the figure as these four years were combined in the source records. The data presented in Figure 1 are based on data reported to the Department of Health and Children,2 the National Disease Surveillance Centre3 and the Health Protection Surveillance Centre.1, 4 Kelly and Clarke5 reported a fall in the number of HIV cases among injecting drug users between 1994 and 1998, with about 20 cases per year compared to about 50 cases each year in the preceding six years. In 1999, there was a sharp increase in the number of cases among injecting drug users, which continued into 2000, with 69 and 83 new cases respectively.6 Between 2001 and 2003 there was a decline in the number of new injector cases (38, 50 and 49 respectively) when compared to 2000 but the number was higher than in 1998. In 2004, once again there was an increase (to 71 cases) in the number infected through injecting drug use compared to the preceding three years. In 2005 there were 66 cases infected through injecting drug use. It was difficult to interpret the trend due to the relatively small numbers diagnosed each year, so a smoother curve (red line in Figure 1) was calculated using a rolling centred three-year average. This curve presents an increase in the annual number of HIV cases in 1999; this higher number of cases was sustained between 2000 and 2004. This indicates a true increase in the number of cases.

1.    Health Protection Surveillance Centre (2005) Newly diagnosed HIV infections in Ireland: quarters 3 & 4 2004, and 2004 annual summary. Dublin: Health Service Executive.

2.    O'Donnell K, Cronin M and Igoe D (2000) Review of the epidemiology of AIDS in Ireland 1983–1999. Dublin: National Disease Surveillance Centre.

3.    National Disease Surveillance Centre (2004) Newly diagnosed HIV infections in Ireland. quarters 3 & 4 2003, & 2003 annual summary. Dublin: National Disease Surveillance Centre.

4.    Health Protection Surveillance Centre (2006) Newly diagnosed HIV infections in Ireland: quarters 3 & 4 2005, and 2005 annual summary. Dublin: Health Protection Surveillance Centre.

5.    Kelly GE and Clarke SM (2000) Has there been a turning point in the numbers of AIDS and HIV antibody positive cases in Ireland? Irish Journal of Medical Science, 169(3): 183–186.

6.    National Disease Surveillance Centre (2001) HIV and AIDS: updated 2000 figures. Dublin: National Disease Surveillance Centre.

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