transmit HIV during pregnancy, while giving birth and, following the birth, through their breast milk. Acquired immunodeficiency syndrome (hereinafter also “AIDS”) is the final stage of the HIV infection. It is a medical condition that occurs 7 to 10 years after a person has become an “asymptomatic carrier of HIV.” It is characterized by a significant weakening of the body’s defense system, which causes a series of severe illnesses that may result in death. The infections that accompany AIDS are known as “opportunistic” infections because the pathogens that cause them take advantage of the opportunity offered by a weakened immune system.23 36. The most common opportunistic diseases and infections include bacterial diseases such as tuberculosis; protozoal diseases such as pneumonia; fungal diseases such as candidiasis; viral diseases such as herpes, and HIV-associated malignancies such as Kaposi sarcoma, lymphoma and squamous cell carcinoma. HIV is transmitted through blood or products derived from contaminated blood, through sexual relations, vertically (mother-tochild) and by workplace accidents or accidental perforation with medical instruments or contaminated needles. The natural course of an HIV infection is divided into four stages: (a) eclipse period (1-2 weeks); (b) primary or acute infection (2-4 weeks); (c) chronic infection or clinical, but not virological or immunological, latency (2-20 years), and (d) AIDS stage (1-2 years).24 37. Antiretroviral therapy (ART) suppresses viral replication and may greatly improve quality of life, but does not eliminate HIV disease. The first treatment with antiretroviral drugs offers the best chance of effectively suppressing the virus, immune recovery and clinical benefit. However, for the treatment to be successful, the drugs must be taken as prescribed. One of the main characteristics of the HIV virus is its genetic diversity, in view of its high replication, the tendency for errors in the reverse transcriptase, and the large number of people infected. This characteristic results in high rates of mutation of the virus. Thus, patients with HIV must adhere to their treatment strictly because, to the contrary, the virus can mutate making it resistant to the antiretroviral drugs. 25 38. According to the World Health Organization (hereinafter also “WHO”), the early use of ART for people living with HIV reduces the risk of transmitting the virus to their sexual partners and to individuals with whom they share drugs. It has also been established that treatment of HIV/AIDS requires not only the treatment of those living with the virus, but also of their partners, even if the latter do not have the virus, and other key populations. In this regard, WHO has recommended that, in partnerships where one of the partners does not have HIV, both partners should be given ART to reduce the risk of transmission of the Cf. Joint United Nations Program on HIV and AIDS (UNAIDS), Comunicar en VIH y SIDA, Manual de capacitación en VIH y SIDA para comunicadores sociales, STATOIL, 1ra. Edición, Caracas, 2006, p. 4; World Health Organization (WHO), Elimination of mother-to-child transmission (EMTCT) of HIV and syphilis: Global guidance on criteria and processes for validation, 2015, p. 3, and Joint United Nations Program on HIV and AIDS (UNAIDS), HIV-related opportunistic diseases, 1999, p. 3. Available at: http://data.unaids.org/publications/irc-pub05/ opportu_en.pdf 23 Cf. Joint United Nations Program on HIV and AIDS (UNAIDS), HIV-related opportunistic diseases, 1999, p. 2. Available at: http://data.unaids.org/publications/irc-pub05/opportu_en.pdf, and expert opinion provided by Ricardo Boza Cordero at the public hearing held before the Court and written report on this opinion (merits file, folios 1459 and 1460). 24 Cf. Joint United Nations Program on HIV and AIDS (UNAIDS), UNAIDS Terminology Guidelines (evidence file, folio 8456); World Health Organization, Consolidated guidelines on the use of antiretroviral drugs for treating and preventing HIV infection. Recommendations for a public health approach (evidence file, folios 14346 and 14461), and expert opinion provided by Ricardo Boza Cordero at the public hearing held before the Court and written report on this opinion (merits file, folios 1458 and 1467). 25 12