The U.S. Centers for Disease Control recommends that the following measures be undertaken to reduce the risk for histoplasmosis in HIV-infected patients with CD4 cell counts <150 cells/μL who reside in the endemic area: avoid disturbing soil contaminated with chicken or bird guano; spelunking; remodeling, demolishing or cleaning old buildings; or cleaning chicken coops [67]. The gene discussed is CD4; the disease is histoplasmosis.