The number of polio cases in Yemen has risen to 63 and more are expected, the World Health Organization (WHO) confirmed on Sunday in the capital, Sana.
There were 22 cases confirmed in the first week of May. Aid agencies are continuing their drive to raise polio awareness and immunisation as quickly as possible, in the face of what has been termed a "major outbreak" by the WHO. Until this outbreak, the country had been categorized as polio free since 1996.
The United Nations Children’s Fund (UNICEF), one of the major partners in Yemen's polio eradication programme, has launched a campaign to promote polio awareness and inform communities about the vaccine.
"We're trying to mobilise everything we can. This is a huge effort involving the mosques, community leaders, schools and radio programming," UNICEF communications coordinator, Naseem Ur-Rehman, said on Sunday.
Polio is a highly infectious viral disease. It invades the nervous system and can cause total paralysis in a matter of hours.
The 3,500 mosques participating in the campaign will incorporate a message about the importance of polio vaccination into Friday prayer services. It also aims to reach Yemeni children through radio programmes on school channels and through mobile units spreading the message.
Even during Yemen's last polio immunisation campaign in April, before the outbreak was detected, announcements from vans equipped with loudspeakers could be heard through the streets of Sana, urging parents to take their children for vaccination.
UNICEF is now working to increase the fleet of mobile announcers and to repair public address equipment for its new awareness campaign.
"We are trying to neutralise the conflicting messages that vaccines don't work," Ur-Rehman added.
Even with proper vaccination, Yemeni children face particular problems in gaining immunity from the vaccine.
"Diarrhoea is very common. The vaccine is given by mouth and it can go out and this is not efficient," Dr Kamel Ben Abdallah, UNICEF's health officer in Yemen told IRIN.
The health expert pointed out that other factors can also impede the efficiency of the vaccine.
"Severely malnourished children do not respond to the vaccine," he explained.
Polio is detected through a method called Acute Flaccid Paralysis (AFP) surveillance. Children displaying AFP symptoms such as numbness are recorded and provide two stool samples, which are sent to nearby countries for analysis in a WHO accredited laboratory.
UNICEF is also helping Yemen with the procurement of polio vaccines and 11 million doses will be delivered later this month, targeting around five million children. They will be administered in two rounds, the first running from 30 May to 1 June.
According to a statement from the WHO, Yemen is using a new monovalent vaccine, specifically targeting the type 1 polio that has been detected in Yemen, as opposed to the previous vaccine which effective against all three types of polio.
All types of polio virus are very similar but type 1 is the most common and the easiest to detect.
The WHO's polio eradication campaign suffered a setback in Nigeria in 2003, when some local Muslim leaders asserted that the vaccine was part of a sterilisation campaign and that it would spread HIV.
The virus spread to other African countries, including Sudan, from where it migrated to Yemen earlier this year officials said.