Ebola guinea
A Guinean student gets her temperature checked on 19 January 2015 in ConakryCELLOU BINANI/AFP/Getty Images

New cases of Ebola in Guinea and Sierra Leone have risen for the second week in a row, the World Health Organization reports, after the battle against the virus appeared to be won.

The decline in new cases throughout April and May, WHO announced, has reversed in two of the nations hardest hit by the virulent, and often fatal, illness that can cause internal and external bleeding in its victims.

As of 7 June, 16 new cases were reported in Guinea and 15 in Sierra Leone respectively. For Sierra Leone, this marks the highest spike in cases since 10 May. Guinea has also seen an increasing number of cases since that date.

In Guinea, the source of five infections is still unknown and WHO teams are investigating.

The health authority could not immediately attribute the cause of this rise.

A total of 27,237 people in Liberia, Guinea, and Sierra Leone were infected during the outbreak, with a 11,158 people dying from infection. Liberia was declared Ebola free on 12 May.

The rise was noted as the UK handed out medals to physicians and microbiologists who helped stem the spreading tide of the virus last year.