HIV/AIDS

HIV causes AIDS by destroying immune cells

Human Immunodeficiency Virus (HIV) is a retrovirus that can progress, if untreated, to the acquired immunodeficiency syndrome (AIDS). The primary target of HIV are cells of the human immune system, the CD4+ T cells, which are used for viral replication. Ultimately, these cells will be destroyed, leading to immunodeficiency in the patient.

Disease progression varies between patients

In the absence of antiretroviral therapy, HIV infection progresses over time from clinical latent HIV infection to early symptomatic HIV infection and ultimately to AIDS, the most severe manifestation of HIV infection. The average time of progression from HIV infection to AIDS is about ten years, but varies between individuals. AIDS is characterized by opportunistic infections and malignant tumors that are usually unable to develop in those with a healthy immune system and which can be fatal.

Disease stage determined by number of CD4+ T cells

Disease progression is associated with a decrease in the number of CD4+ T cells and an increase in virus particles (‘viral load’). The stage of HIV infection is determined by measuring the amount of CD4+ T cells and viral load in the blood. When the number of these cells drops below a critical level, symptoms of opportunistic infections will appear (often around or below 200 CD4+ T cells per microliter (µL)). The definition of AIDS includes both laboratory and clinical findings. Treatment should be started before the patient’s CD4+ count drops below 200, but most national guidelines recommend starting treatment around CD4+ cell counts of 350. For more information, see WHO, 2006f.

ICD classification follows the pattern of co-morbidity

In the ICD-10 classification AIDS and HIV-infections are classified as follows (WHO, 2007r):

• HIV disease resulting in infectious and parasitic diseases (ICD-10 code B20);
• HIV disease resulting in malignant neoplasms (ICD-10 code B21);
• HIV disease resulting in other specified diseases (ICD-10 code B22);
• HIV disease resulting in other conditions (ICD-10 code B23);
• Unspecified HIV disease (ICD-10 code B24).

HIV infection rates vary greatly across Europe

In 2006, 86,912 newly diagnosed HIV cases were reported from 50 of the 53 countries in the WHO European region, of which 26,220 (30%) cases were reported in the 27 countries of the European Union. The rate of HIV-infection varies considerably across Europe, as shown by the Newly diagnosed HIV infection rates in four European regions. The highest rates are observed in the East (210.8 per million population), nearly three times the rates reported in the west (82.5 per million) and over twenty times that in the centre (9.4 per million). Of the 27 EU member states, 16 are assigned to the ‘west’ region, eight to the ‘centre’ and three to the ‘east’. Due to the large proportion of western European countries within the EU, the epidemiology of HIV in the EU reflects that of the west region. It should be noted that the HIV-infection rate in western Europe is underestimated, due to the fact that no national data are reported for Italy and Spain (countries with high rates of HIV infection) (EuroHIV, 2007a, EuroHIV, 2007b).

HIV prevalence relatively low but on the rise in western and central Europe

An estimated 0.3% of the adult population in western and central Europe are infected by HIV (www.unaids.org). After the introduction of highly active antiretroviral therapy (HAART) in 1996, the number of AIDS cases and AIDS related deaths dropped significantly in Western Europe. However, the number of reported HIV infections has continued to rise. The parallel or diverging trends of newly diagnosed HIV and AIDS rates are shown in Trends in HIV incidence rates in selected countries, Newly diagnosed HIV infection rates in four European regions, Trends in AIDS incidence rates in selected countries, and Newly diagnosed AIDS cases in four European regions. The number of new HIV diagnoses among men who have sex with men (MSM) increased by almost 50% since 2000, underlining the need for renewed prevention efforts targeted at MSM. The increasing prevalence of infection among heterosexuals is largely due to immigration. The proportion of heterosexually acquired HIV cases in persons originating from high prevalence countries varied from 22% in Portugal to 71% in Belgium and Sweden, reinforcing the need to ensure that prevention and care services are adapted to reach immigrant populations (EuroHIV, 2007a, EuroHIV, 2007b).

HIV infection rate highest in Eastern Europe

HIV prevalence among adults living in eastern Europe is estimated at 0.9% (www.unaids.org). Although the rate of new HIV infections appears stable after the steep increase observed in 2001, an increase in the number of new HIV cases was again reported in 2005. Nearly 90% of the newly reported HIV diagnoses in this region in 2006 were from two countries: the Russian Federation (66%) and Ukraine (21%). A map shows the HIV cases diagnosed in the WHO European region, 2006. The corresponding AIDS incidence rates are shown by AIDS cases diagnosed in the WHO European region, 2006.

The HIV epidemic in eastern Europe is mainly driven by injecting drug use. Additionally, the number of infections that were reported as heterosexually acquired has doubled since 2005, which highlights the need for initiatives to control transmission in the heterosexually active population. The relative importance of four transmission routes is shown in Predominant transmission route for HIV by country.

Strong link between STI incidence and possible spread of HIV-infection

Having other sexually transmitted infections (STI) increases the risk of HIV infection for both men and women. The prevalence of HIV is relatively low in Europe and HIV infections are largely restricted to high risk groups. Therefore, the monitoring of HIV prevalence among STI patients can give an early indication of how HIV is likely to spread in the general population.

Tuberculosis is an AIDS-defining illness in Europe

In 2005, 33% of those with AIDS had been diagnosed as having tuberculosis (TB) as well, making TB an AIDS-defining illness. In eastern Europe over half of the AIDS cases (54%) were diagnosed with TB and in western and central Europe this was 22%. Thus, tuberculosis is one of the most important indicators of AIDS. In western European countries, the prevalence of TB among new AIDS cases is largely due to the immigration of persons from sub-Saharan African countries, while Kaposi sarcoma, another AIDS-defining illness, is more often related with sex between men.

More than 33 million peope are living with HIV/AIDS worldwide

Globally an estimated number of 33.2 million people were living with HIV/AIDS in 2007. In 2007, the estimated number of deaths due to AIDS was 2.1 million worldwide, of which 76% occurred in sub-Saharan Africa. In 2007, there were approximately 1.6 million people living with HIV in Eastern Europe and Central Asia, and a total of 55,000 have died of AIDS. In Western and Central Europe the number of people living with HIV was much lower (760,000), and the number of people who died from AIDS was 12,000. For mortality rates by country and by larger region, see: Trends in mortality (SDR) from HIV/AIDS in selected countries, and the Trends in AIDS mortality in four European regions. As a large number of AIDS cases and deaths are not reported, the actual infection and death rates are most likely higher (UNAIDS, 2007).

Antiviral therapy causes a decline in AIDS mortality in Europe

The decline in AIDS death rates that is observed in most European countries, is due to the life-prolonging effects of effective antiretroviral therapy (HAART). In the EUROSIDA study, the number of deaths dropped from 14.6 per 100 persons/year in the pre-HAART period to 9.3 per 100 in the early-HAART period to 2.6 in the late-HAART period (Mocroft et al., 2003)

Health burden

The prognosis for people with HIV has changed considerably since the first cases of AIDS were diagnosed in the early 1980s. The use of Highly Active Antiretroviral Therapy (HAART) from the mid-1990s onwards, has led to dramatic improvements in the prognosis of people with HIV. By the end of 2006, HAART had become available in 51 out of the 53 countries in the WHO European region, but access to treatment varies between countries (WHO, 2006f). People living with HIV who receive HAART before the immune system is damaged, are drug-compliant and are able to tolerate the therapy, can live a more or less normal life span. However, many HIV infected people do not know their HIV status, and are in some cases too far advanced when finally diagnosed, to fully benefit from treatment and care.

Late presentation is detrimental for both individual morbidity and mortality, and for public health because people who are unaware of their HIV status can further spread the virus. Access to HIV testing, treatment and care is fairly good in western and central Europe, but remains a challenge in eastern Europe, in particular for intravenous drug users. In western Europe, migrant populations face more difficulties in accessing testing and treatment services.

Financial burden

HIV treatment is costly. The total cost comprises the costs of HAART, disease monitoring and hospitalisation. The costs of first line therapy (per patient per year) tend to vary considerably across Europe (estimates of average costs range between €600 and 14,000), depending on various factors such as financial support by the Global Fund for AIDS, TB and Malaria (Mounier-Jack et al., 2008).

Highest transmission risk from blood and semen

Blood and semen of HIV infected people contain high concentrations of HIV. In vaginal fluid the concentration is significantly lower. The virus can also be present in other body fluids, such as saliva, sweat, tear drops and urine. The concentration in these fluids, however, is too low to be infectious.

Unsafe practices in relation to infected blood, semen and vaginal fluid can create a risk of infection. The virus can also be transmitted from mother to child, during pregnancy, at birth or after birth (through breastfeeding).

Possible transmission routes are manifold

HIV is known to be transmitted via the following routes:

• Through unprotected anal or vaginal sexual contact with an infected person. The risk of infection through heterosexual intercourse with an infected person is relatively small: around 0.1% per unprotected contact. The risk of transmitting the virus is higher for anal intercourse: 0.8%-3.0%. Also, the risk of transmission is higher from male to female. Finally, the risk is higher for the receptive sexual partner than for the insertive sexual partner (Holmberg et al., 1989).
• Through exposure to infected blood, by sharing contaminated needles or syringes (e.g. injecting drug users).
• Through transmission from mother to child, during pregnancy, birth or from breastfeeding. The risk of transmission depends on the number of virus particles in the mother’s blood.
• Through accidental puncture wounds acquired during the medical treatment of an HIV-infected patient. The risk of infection after such an injury is estimated at 0.3% (Gisselquist et al., 2006).
• Through blood transfusions and organ transplants. The risk of transmission through intravenous exposure to HIV infected blood is very high: 60-95%.The careful screening and selection of donors (those at risk of contracting HIV are asked not to donate their blood) now carried out virtually prevents the transmission of HIV through blood transfusions (Schreiber et al., 1996).

Transmission through spit and household contact (dinnerware, cutlery, bathroom hygiene) does not occur.

Transmission risk is greatest shortly after infection and several years later

The risk of transmission is highest shortly after infection and several years later, when the infection has become symptomatic. The prevalence of the infection and the risk of infection together determine whether transmission takes place per contact.

STI increase infection risk

The risk of infection is increased through simultaneous infection with other sexually transmitted infections (STI). Those infected with HIV are also more susceptible to contracting other STI and to a greater number of complications (Fleming & Wasserheit, 1999). The risk of HIV transmission is therefore greatly reduced where preventive measures are put in place to combat STI.

Antibodies and viral load used in diagnosis of HIV

HIV infection can be diagnosed when the presence of specific antibodies is indirectly demonstrated or when virus particles are directly detected. In the latter case the presence and the level of HIV-RNA (viral load) in the blood is determined. A prognosis of the progress of the disease can be made on the basis of the identified viral load and the number of detected CD4+ T cells.

Transmission from mother to child does not always occur

HIV can be transmitted from a mother to her baby, but this does not occur in every case. All babies of infected mothers have antibodies in their blood that originate from the mother. These antibodies disappear after about 18 months. Therefore, testing newborn babies on the presence of antibodies does not prove useful, as the antibodies detected may not belong to the baby itself. Therefore, it is only useful to test a baby on antibodies for HIV after 15 months. The direct detection of the virus or parts of the virus does, however, offers a suitable testing method for newborns (Krist & Crawford-Faucher, 2002). Antiretroviral treatment of the mother reduces the risk of transmission to her (unborn) child significantly (McGowan & Shah, 2000a, McGowan & Shah, 2000b, Ioannidis et al., 2001).

No cure for HIV and AIDS but treatment can prolong life expectancy

Both HIV infection and AIDS cannot be cured, but they can be treated. Treatment builds on two measures. The first measure consists of inhibiting the progress of infection through drugs that act against the virus. These drugs are also known as HIV inhibitors or antiretroviral drugs. The second measure aims at preventing and treating opportunistic infections, such as pneumonia, as much as possible.

Since 1996, highly active antiretroviral therapy (HAART) has been generally available. Three to four drugs with different mechanisms are combined in this therapy. The aim is to inhibit the production of the virus, to block the integration in human cells, and subsequently allow the immune system, which is no longer affected, to recuperate. This therapy prolongs the survival of AIDS patients significantly.

Prevention measures in the European Union

Currently, there is no effective vaccine to prevent transmission of HIV. Several candidate vaccines are in development and tested in clinical trials, but so far results have been disappointing. Most European countries have reduced the rate of HIV transmission in medical settings (through blood screening and universal precautions) and from mother to child (through routine screening, use of preventive drugs, preventive measures during the delivery, and advising mothers who are infected not to breastfeed). Countries that have implemented comprehensive harm reduction programmes, (e.g. needle exchange programmes, methadone maintenance), such as the UK, Germany and the Netherlands, have also maintained a very low rate of infection among injecting drug users.

Recently the number of sexual transmitted infections and HIV infections in migrants and men having sex with men has increased. This, together with the increase in unsafe sexual behaviour this emphasises the importance of reinforced prevention programmes aimed at men who have sex with men, migrants from HIV endemic countries, young people, commercial sex workers, drug users and HIV infected people.

The European Commission still considers prevention of new infections as the central instrument in the fight against HIV and pleads in that framework for an evidence-based approach. In such an approach, prevention programmes are combined with a good and accessible information supply, counselling and recommendations, treatment, care and support.

Key priorities on European level includes: increasing voluntary HIV testing, scaling up HIV prevention, reducing risk behaviour in men having sex with men, and providing specific services for migrant communities (Amato-Gauci et al., June 2007), UNAIDS, 2004b, Hamers & Downs, 2004, Hamers et al., 2006).

Drug use

Health inequalities

EuroHIV European Centre for the Epidemiological Monitoring of AIDS

UNAIDS The Joint United Nations Programme on HIV/AIDS

Trends in mortality (SDR) from HIV/AIDS per 100,000 population, in selected countries, 1980-2005 (interactive)

Trends in newly diagnosed HIV infection rates per million population, in four European regions, 1994-2006

Trends in newly diagnosed AIDS cases per million population, in four European regions, 1988-2006

Trends in AIDS mortality per million population, in four European regions, 1988-2006

Trends in AIDS incidence rates in selected countries, 1999-2006 (interactive)

Trends in HIV incidence rates in selected countries, 1999-2006 (interactive)

Number of AIDS cases in European countries, in 2006.

Number of HIV cases in European countries, in 2006.

Predominant route of HIV transmission for newly diagnosed cases in European countries, in 2006.

Data are for men and women together.

Graph includes countries providing data for the entire periods shown.

EU is EU-27.

The region 'West' includes: Andorra, Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Israel, Italy, Luxemburg, Malta, Monaco, Netherlands, Norway, Portugal, San Marino, Spain, Sweden, Switzerland, United kingdom (total population 408 million).

The region 'Centre' includes: Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Czech Republic, Hungary, Former Yugoslav Republic of Macedonia, Montenegro, Poland, Romania, Serbia, Slovakia, Slovenia, Turkey (total population 192 million).

The region 'East' includes: Armenia, Azerbaijan, Belarus, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Republic of Moldova, Russian Federation, Tajikistan, Turkmenistan, Ukraine, Uzbekistan (total population 284 million).

HIV data by year of report. Countries excluded: West: Andorra, Austria (EU), France (EU), Greece (EU), Italy (EU), Malta (EU), Monaco, Netherlands (EU), Portugal (EU), Spain (EU); East: Uzbekistan.

Graph includes countries providing data for the entire periods shown.

EU is EU-27.

The region 'West' includes: Andorra, Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Israel, Italy, Luxemburg, Malta, Monaco, Netherlands, Norway, Portugal, San Marino, Spain, Sweden, Switzerland, United kingdom (total population 408 million).

The region 'Centre' includes: Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Czech Republic, Hungary, Former Yugoslav Republic of Macedonia, Montenegro, Poland, Romania, Serbia, Slovakia, Slovenia, Turkey (total population 192 million).

The region 'East' includes: Armenia, Azerbaijan, Belarus, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Republic of Moldova, Russian Federation, Tajikistan, Turkmenistan, Ukraine, Uzbekistan (total population 284 million).

AIDS data by year of diagnosis adjusted for reporting delays. Countries excluded: West: Andorra, Monaco; East: Azerbaijan, Uzbekistan.

Graph includes countries providing data for the entire periods shown.

EU is EU-27.

The region 'West' includes: Andorra, Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Israel, Italy, Luxemburg, Malta, Monaco, Netherlands, Norway, Portugal, San Marino, Spain, Sweden, Switzerland, United kingdom (total population 408 million).

The region 'Centre' includes: Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Czech Republic, Hungary, Former Yugoslav Republic of Macedonia, Montenegro, Poland, Romania, Serbia, Slovakia, Slovenia, Turkey (total population 192 million).

The region 'East' includes: Armenia, Azerbaijan, Belarus, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Republic of Moldova, Russian Federation, Tajikistan, Turkmenistan, Ukraine, Uzbekistan (total population 284 million).

Data by year of death adjusted for reporting delays. Countries excluded: West: Andorra, Monaco, Netherlands (EU); East: Azerbaijan, Uzbekistan.

Data are for men and women together. Data are adjusted for reporting delay. Due to differences in estimation methods, data adjusted may differ slightly from those presented in national reports.

Data are for men and women together

France: new HIV reporting system started in 2003; Greece: retrospective reporting before 1999, data for 1999 include many cases diagnosed earlier; Italy: data based on reporting in 10 regions (34% of the population); Netherlands: new HIV reporting started in 2002; this year's data include many cases diagnosed earlier, same for 1999; Portugal: HIV reporting changed in 2000, data for 2000 include many cases diagnosed earlier; Spain: data based on 8 regions (32% of the population); Russian federation: excluding mother-to-child cases.

Authors: Op de Coul ELM, Koedijk FDH (RIVM, Bilthoven, The Netherlands)

Editor: Kramers PGN (RIVM, Bilthoven, The Netherlands)

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