HIV/AIDS policy fails to address the reasons why sex and birth are more risky in Africa. Malnutrition lowers immunity and increases viral load in HIV-infected persons, making them more contagious. Malaria also increases viral load and thus the risk of sexual and vertical HIV transmission. Schistosomiasis increases risk of sexual transmission of HIV by lowering immune response and by causing genital lesions and inflammation. The weaknesses of developing economies and governance structures also interact with health variables. Often the best investment for improving health and preventing disease is outside the health sector. HIV prevention must go beyond last-minute interventions, such as promoting abstinence or condom use, and address the economic context in which risky behaviors occur.