Sometimes a person should stop digging. The drug has been widely used world wide since the 1930’s. There are known side effects that are seen in long term therapy.
Research by German scientists to discover a substitute for quinine led to the synthesis in 1934 of Resochin (chloroquine) and Sontochin (3-methyl-chloroquine). These compounds belonged to a new class of antimalarials, the four-amino quinolines.
Following the war, chloroquine and DDT emerged as the two principal weapons in WHO’s global eradication malaria campaign. Subsequently, chloroquine resistant P. falciparum probably arose in four separate locations starting with the Thai-Cambodian border around 1957; in Venezuela and parts of Colombia around 1960; in Papua New Guinea in the mid-1970s and in Africa starting in 1978 in Kenya and Tanzania and spreading by 1983 to Sudan, Uganda, Zambia and Malawi.
Chloroquine was recently studied in pregnant women for Zika prophylaxis https://www.nature.com/articles/s41598-017-15467-6
Again. The question is not can it be taken. The question is does it work? We can know the answer to that question right now.
Not many are familiar with Difluorodiphenyltrichloroethane or DFDT, which the German army favored over DDT. It killed insects four times as swiftly with a smaller application; and, did not provide survival rates which would allow development of resistance to this insecticide.