From 1990 to 1998, new diagnoses of HIV infection in the United Kingdom (UK) averaged 2675 per year, most among homosexual men. In 1999, however, a rapid increase in numbers of new diagnoses began (figure 1). By the end of March this year there were 5338 reports of new HIV diagnoses in 2002, representing a 28% increase on numbers of new diagnoses in 2001, reported by the same time last year. The number is predicted to rise to over 6000 new HIV diagnoses in 2002 as further reports are received. In contrast, the numbers of new AIDS diagnoses increased annually peaking in 1994 at 1854, until the widespread use of highly active antiretroviral therapy (HAART) in the mid nineties led to a fall, numbers stabilising in the late nineties, with 647 new AIDS diagnoses in 2002 reported so far.

Figure 1: HIV diagnoses and AIDS cases by year of first diagnosis in the United Kingdom:

(Data to end of March 2003)

Reports of new HIV diagnoses in the UK are received from laboratories and clinicians, the latter also reporting new AIDS diagnoses. Data presented are from reports received at the Communicable Disease Surveillance Centre by the end of March 2003.

Between 1999 and 2002, there were 17 188 new HIV diagnoses; 3058 in 1999, rising to 5338 in 2002, an increase of over 75%. Of those newly diagnosed with HIV during this period, where probable route of infection was reported, 9130 (57%) probably acquired infection heterosexually and 5985 (37%) through sex between men (table 1). Injecting drug use only accounted for 431 infections, and mother to child exposure for 358. One thousand one hundred and sixty nine (6.8%) of individuals do not yet have a probable route of infection assigned; this will decrease as follow up continues.

Table 1: New HIV diagnoses in the United Kingdom between 1999 and 2002, by sex and probable route of exposure
(Data to end of March 2003)

Exposure route	Male	Female	Total(%)
Sex between men*	5985	-	5985(35)
Heterosexual sex**	3472	5657	9130(53)
Injecting drug use	306	125	431(3)
Blood transfusion/products	41	48	89(1)
Mother to child	184	174	358(2)
Other	17	9	26(0.2)
Undetermined**	709	459	1169(7)
Total	10714	6472	17188
*includes 86 individuals who also injected drugs
**total includes 1 individual of unreported sex

Of the 9130 individuals who acquired infection heterosexually, 3472 (38%) were male and 5657 (62%) female. Where ethnicity was reported, 6095 (73%) were black African, 1410 (17%) white, and 407 black Caribbean (table 2). Where reported, 6686 (78%) were probably infected in Africa, 974 (11%) in the UK, and 374 in Asia (table 3). Heterosexual transmission within the UK is likely to be underestimated, because if an individual has been exposed to infection in more than one area of the world, probable country of infection is allocated to the area with the highest prevalence. In comparison, of the 5985 homosexual men, 3901 (88%) were white, with most (84%) for whom a likely country of infection has been recorded, probably infected in the UK.

Table 2: New HIV diagnoses in the United Kingdom between 1999 and 2002, by probable route of infection and ethnicity
(Data to end of March 2003)

Ethnic group	Men who have sex with men	Heterosexuals	Other/ Undetermined	Total (% of sub total)
White	3901	1410	593	5904(42)
Other/mixed	206	216	89	511(4)
Black Caribbean	165	407	41	613(4)
Black African	82	6095	564	6741(48)
Black other	51	91	11	153(1)
Indian/Pakistani/ Bangladeshi	51	130	29	210(2)
Sub total	4456	8349	1327	14132
Not reported	1529	781	746	3056
Total	5985	9130	2073	17188

 

Table 3: New HIV diagnoses in the United Kingdom between 1999 and 2002, by probable route of infection and probable region/country of infection
(Data to end of March 2003)

Probable country/region of infection*	Men who have sex with men	Heterosexuals	Other/ Undetermined	Total(% of sub total)
UK	2213	974	206	3393(28)
Africa	52	6686	397	7135(59)
Asia	42	374	42	458(4)
Australasia	32	16	5	53(0.4)
Europe	160	200	133	493(4)
Latin America/ Caribbean	75	299	13	387(3)
North America	60	24	7	91(1)
Sub total	2634	8573	803	12010
Not reported	3351	557	1270	5178
Total	5985	9130	2073	17188

There were 2867 new AIDS diagnoses between 1999 and 2002. As AIDS has become a poorer marker of infection progression since the introduction of HAART, reporting of AIDS, particularly when it is not present at HIV diagnosis, may have decreased, and this may underestimate the true number of new diagnoses over the period. Where probable route of infection was reported, 1524 (54%) of those diagnosed with AIDS probably acquired infection heterosexually and 998 (36%) through sex between men. An individual may have more than one AIDS defining illness at the time of first AIDS diagnosis. Pneumocystis carinii pneumonia (PCP) was the most frequently diagnosed AIDS defining condition among men who have sex with men, with 442 diagnoses. Among heterosexuals, tuberculosis was diagnosed in 565 individuals, reflecting the high numbers of black Africans in this exposure group, and PCP was diagnosed in 419 individuals (table 4).

Table 4: Initial AIDS defining illnesses and number new AIDS diagnoses by probable route of infection, United Kingdom 1999-2002
(Data to end of March 2003)

Probable route of infection
Initial AIDS defining illness	Men who have sex with men	Heterosexuals	Other	Total(%)
Kaposi's sarcoma	175	81	5	261(8)
Lymphoma	75	51	21	147(4)
Mycobacterium - other	42	57	8	107(3)
Mycobacterium tuberculosis	39	565	32	636(19)
Candidiasis	127	163	42	332(10)
Pneumocystis carinii pneumonia	442	419	112	973(28)
Other opportunistic infection	165	354	121	640(19)
Wasting	86	108	63	257(8)
Encephalopathy	31	26	25	82(2)
Total	1182	1824	429	3435
Total number of individuals*	998	1524	345	2867
*An individual may have more than one initial AIDS defining illness

The UK's HIV epidemic has changed substantially over the past decade, moving from one predominantly affecting white homosexual men, to one where HIV heterosexually acquired in Africa is driving significant rises in numbers of new HIV diagnoses here. Nevertheless, new diagnoses among white homosexual men continue. In sharp contrast, AIDS diagnoses have fallen since the introduction of HAART.

The need to recognise the diversity of the people affected has been acknowledged by the UK government's National Sexual Health Strategy (1), but effective action to reduce further spread of HIV within the UK will be hampered if resources are inadequate to meet the rapidly increasing prevention and care needs.

UK data from the Health Protection Agency Communicable Disease Surveillance Centre (CDSC), Scottish Centre for Infection and Environmental Health, and the Institute of Child Health, London.