Tablets of ivermectin, or Mectizan by trade name, are seen in this photo provided by MSD.

Kitasato University distinguished emeritus professor Satoshi Omura is seen in this August 2014 file photo. (Mainichi/Yohei Koide)

TOKYO -- An American research team has reported that ivermectin, a medication used to treat head lice and other parasitic infestations, is effective in reducing the mortality rate of the novel coronavirus.

According to the team, the death rate of coronavirus patients declined to about one-sixth, compared to the rate of death in those who did not use the medication.

The medication was developed based on substances produced by bacteria, discovered by Kitasato University distinguished emeritus professor Satoshi Omura, winner of the 2015 Nobel Prize in physiology or medicine. It has been used to treat onchocerciasis, a disease caused by parasites with symptoms including blindness, and lymphatic filariasis, a parasitic disease that can cause thickening of the skin.

An Australian research team had initially confirmed in experiments on cells that ivermectin is effective in reducing the amount of novel coronavirus molecules. The team says a dose of the treatment suppressed virus growth within one or two days of administration.

The American team collected data of coronavirus patients who received some kind of treatment between January and March 2020. Researchers carried out statistical analysis by comparing 704 cases in which patients were administered with ivermectin at 169 medical institutions in Asia, Europe and North America to 704 cases in which the medication was not used.

Of the patients who had to use ventilators, the death rate of patients who were not treated with ivermectin stood at 21.3%, while the figure for those who received the medication stood at 7.3% -- about one-third of the former figure. Furthermore, the mortality rate of all patients stood at 1.4% for those who were administered ivermectin. This was roughly one-sixth of the death rate for people who did not use the medication, which stood at 8.5%.

The team says the use of ivermectin is also effective in shortening the days a patient needs to be hospitalized, serving as a point of reference when considering treatment methods.

(Japanese original by Ryo Watanabe, Science & Medical News Department)