MOSCOW, June 19 (RIA Novosti) - A total of 44,287 cases of human A/H1N1 infection have been registered in 95 countries worldwide, with 180 deaths, the World Health Organization (WHO) said in a report on Friday.

A total of 4,667 new cases have been registered and 13 people have died in the past 24 hours, WHO also said.

Mexico has seen the most fatalities, with 7,624 cases and 113 deaths. The U.S. has so far seen 17,855 cases and 44 deaths. Other countries to be hit include Canada (4,905 cases, 12 deaths), Chile (3,125 cases and two deaths) and Australia (2,199 cases, no deaths).

WHO decided to raise its pandemic alert level to the maximum of 6 on June 11.

An influenza pandemic is an epidemic of an influenza virus that spreads on a worldwide scale and infects a large proportion of the human population.

There were three flu pandemics in the last century. The 1918 Spanish flu was the most serious pandemic, claiming over 50 million lives. It was followed by the Asian Flu in 1957 with up to 4 million deaths, and the Hong Kong Flu in 1968 resulting in about 1 million deaths.