He said "with the tools we have today, it is most unlikely eradication will be achieved."
Alonso was presenting the results of a WHO-commissioned report by experts who said they couldn't offer a definitive timeline or cost estimate for malaria eradication because there are too many uncertainties to develop a clear strategy, the AP reported.
Eradicating malaria has long been a goal of WHO, with the first attempt launched in 1955. Malaria kills about 435,000 people worldwide every year, mostly children in Africa.
Smallpox is the only human disease to ever have been wiped out. In 1988, WHO and partners began a global campaign to eradicate polio by 2000, but that effort is still ongoing, the AP reported.