Dar es Salaam (Arabic for "haven of peace"), where the head office of HDT is located, is a city in eastern Tanzania. Formerly Mzizima, Dar es Salaam is the largest city in Tanzania. It was founded in the 1860s as a summer residence for the sultan of Zanzibar and later developed by the Germans in 1885. It was a capital city before the smaller city of Dodoma was designated as the current capital of Tanzania. It is the nation's largest city, chief seaport, and principal commercial, manufacturing, and educational center. Its population in 2005 census was estimated to be about 5 million. It is among the regions with high regional HIV prevalence (10% according to HIV indicator survey of 2004).

Mbeya is a city located in the southwest of Tanzania. Following the 1905 gold rush, Mbeya was founded as a gold mining town in the 1920s. At later stage the TAZARA railway attracted farming migrants and small entrepreneurs to the area. Mbeya and its district was administered by the British until 1961. Its urban population was estimated to be 280,000 in 2005, but total regional population estimated to be approximately 2 million). Mbeya is the first large urban settlement encountered when traveling overland from the neighboring nation of Zambia. Mbeya is situated at an altitude of 1,700m/5500ft, and sprawls through a narrow highland valley surrounded by a bowl of high mountains. Mbeya is one of the regions with the highest HIV prevalence in the country (estimated to be 13% according to the HIV indicator survey of 2004).

Kagera region was formally known as the West Lake region. It was renamed Kagera region after the war between Tanzania and Uganda, when Idi Amin attempted to annex the region in 1979. The region takes its name from the Kagera River, which flows from Rwanda through northern Tanzania before it penetrates the waters of Lake Victoria, to emerge as the river Nile, the longest river in the World. For a period of about five centuries, Kagera Region had nine different Kingdoms and a highly hierarchical society. These kingdoms are Kihanja, Karagwe, Kiziba, Misenye, Bugabo, Kyamtwara, Ihangiro, Bukara and Biharamulo. The kingdoms were blended into the Germans who colonized Tanganyika in 1890. The region is considered to be the first area where Lutheran missionaries settled, with Roman Catholic and other denominations also now enjoying a large following in the region. According to the 2003 National Census, the population is over 2 million people, with an annual growth rate of 3.1%. Kagera region was the first hard hit by HIV in the country and grossly affected by the influx of refugees, both compromising security and impact of HIV to the communities.