Table 1: State variables of the HIV/AIDS basic model.

Symbol Description

𝑆 ( 𝑡 ) Susceptibles or HIV negatives at time 𝑡
𝐼 1 ( 𝑡 ) HIV-infected individuals unaware of their status
𝐼 2 ( 𝑡 ) HIV-infected individuals aware of their status
𝑃 ( 𝑡 ) Pre-AIDS individuals at time 𝑡
𝐴 ( 𝑡 ) AIDS individuals at time 𝑡