Impact of virgin land development on morbidity and mortality from diphtheria in KazakhstanZhanna Mazhitova, Dina Kurbanova, Meruyert Bektayeva, Baktybala Rakhimzhanova, Zauresh Saktaganova, Gulnar Baigozhina and Zhanara AbdukarimovaE3S Web of Conf., 389 (2023) 02021DOI: https://doi.org/10.1051/e3sconf/202338902021