Islamabad, Sep 13 (IANS): The number of polio cases detected in Pakistan this year has increased to 18 after a three-month-old infant in Khyber Pakhtunkhwa's North Waziristan district was paralysed by the virus, the Health Ministry announced.

The Ministry said on Tuesday that the child suffering from polio-induced disabilities had an onset of paralysis on August 25 as confirmed by the Pakistan National Polio Laboratory at the National Institute of Health, reports Xinhua news agency.

All the cases in Pakistan this year were detected in Khyber Pakhtunkhwa, with two patients from its Lakki Marwat and 16 from North Waziristan.

Last week, a positive environmental sample for poliovirus was detected in Karachi, in addition to four other isolates from Bannu, Peshawar and Swat cities of Khyber Pakhtunkhwa, and Lahore, capital of Punjab province, the Ministry said.

"Karachi, home to communities from across Pakistan, is a historic polio reservoir and remains among areas categorized by the program at high risk of wild poliovirus transmission," it added.

The humanitarian crisis in the wake of the unprecedented floods will pose graver challenges to Karachi and other areas of Pakistan in the foreseeable future, as millions of people are displaced and move to urban centres for refuge, said the statement.

It further added that large-scale movement of people, in addition to the high transmission season for the poliovirus, escalates the risk of wild poliovirus spreading.

"Despite the extreme climatic conditions, the Pakistan Polio Program conducted immunization campaign wherever possible, and the program is prepared to restart the campaign in the flood-affected areas as soon as it becomes feasible," Health Minister Abdul Qadir Patel was quoted as saying in the statement.