Sakai , near the regional commercial centre of Osaka , has been hit hardest by the deadly bacteria , with nearly 6,500 , mostly schoolchildren , affected by the disease .
<response> <location>Sakai</location> , near the regional commercial centre of <location>Osaka</location> , has been hit hardest by the deadly bacteria , with nearly 6,500 , mostly schoolchildren , affected by the disease . </response>