The wife of a kidnapped American missionary missing in Africa is appealing for the hostage takers to telephone her and to let her husband go. 

Els Woodke pleads in a video for news of Jeff Woodke, a US aid worker, abducted from their home in Niger in October last year. 

His wife made the appeal through World Watch Monitor after he failed to appear in a video released a few days ago by the jihadists she believes to be his captors. That video showed six hostages, including kidnapped Colombian nun Sister Gloria Argoti. According to the US-based monitoring group SITE, the group is the Islamist al-Qaeda affiliate Nusrat al-Islam wal Muslimeen.

No group has claimed responsibility for taking Woodke but his captors were tracked to Mali by Nigerian authorities, reports WWM.

'Jeff has lived and worked in Niger for more than 29 years,' she tells WWM.

'He leads an NGO that assists the local population with farming, health improvement, access to clean water, literacy and education.' She says he is 'truly loved and respected' by the people of Niger.

In the jihadists' video, in which Woodke was not mentioned, the kidnappers urge the hostage families to 'strive to rescue them'.

Els Woodke urges the hostage takers to call her also, and says Jeff can give them the number.

'I am sure that the families of the captives were very encouraged by this message and appreciated the mercy shown by Jama'at Nusrat al-Islam wal Muslimeen in sending this news and instructions about their loved ones. But my husband Jeff is not mentioned, so I did not receive the benefit of the reassurance and directions of how to proceed that the other families did. This has been very hard for me, for Jeff's sons and his father to understand.'

WWM reports that the kidnapping and ransoming of foreign nationals has become a lucrative business for jihadist groups. On July 2, French President Emmanuel Macron attended a meeting with the leaders of Niger, Mali, Chad, Burkina Faso and Mauritania to allocating troops to fight jihadis.