Twenty-one US states report weekly rise in new casesCases are spiking in parts of California and the southwest of the US, with 21 states reporting weekly increases in new cases.It could lead authorities to reimpose or tighten public health restrictions, with Arizona having already reactivated its emergency plan for medical facilities while California has placed counties where half of its 39 million residents live on a watch list."Many of the cases that are showing up in hospitals are linked to gatherings that are taking place in homes - birthday parties and funerals," said Olivia Kasirye, public health director of Sacramento County, one of the nine counties on California's watch list.Arizona, Utah and New Mexico all posted rises of 40% or higher for the week ending on Sunday, compared with the prior seven days.-bbc.com/news