John Kerry says the US is prepared to do more to help Nigeria fight Boko Haram. <br /><br />The US Secretary of State is visiting the country ahead of next month's presidential election.<br /><br />Kerry has been meeting both contenders, President Goodluck Jonathan and former military leader Muhammadu Buhari.<br /><br />Al Jazeera's Yvonne Ndege reports from Abuja.
