By Anurag Maan and Shaina Ahluwalia

(Reuters) – California on Wednesday overtook New York, the original epicenter of the U.S. novel coronavirus outbreak, as the worst-hit state for cases, according to a Reuters tally of county data.

Total cases in the most populous U.S. state rose by 12,112 on Wednesday to a total of more than 421,000, the biggest single-day increase since the pandemic started. California deaths also set a one-day record, rising by 159.

New York has recorded by far the most deaths of any U.S. state at more than 32,000 with California in fourth place with over 8,000 deaths.

If California were a country, it would rank fifth in the world for total coronavirus cases behind only the United States, Brazil, India and Russia. New York has more than 413,500 cases and has been adding on average 700 new ones a day in July. In California there is an average of 8,300 new cases a day.

The rapid increase of cases has made it difficult to trace the pathogen’s path through the community through contact tracing, a process of interviewing people who test positive for the virus to find out how they were exposed, and whom they in turn might have exposed, California Secretary of Health and Human Services Dr. Mark Ghaly said on Tuesday.

“No one anticipated building a program to contact trace the number of cases we’re seeing here,” Ghaly said at a news conference, referring to Los Angeles and other counties struggling to trace cases of the disease.

Since its crush of cases earlier in the year, New York state has managed to get the virus under control, reporting the fewest hospitalizations in four months on Monday and only two deaths on Tuesday.

Nearly 143,000 Americans have died of COVID-19 – nearly a quarter of the global total.

(Reporting by Anurag Maan and Shaina Ahluwalia in Bengaluru, and Sharon Bernstein in Sacramento, California; Editing by Lisa Shumaker and Jonathan Oatis)