China Sunday stepped up efforts to curb a deadly bird flu outbreak centred on Shanghai, disinfecting schools and shutting down bird markets, as state media criticised “intense” farming for helping spread disease.

China has confirmed 18 cases of the H7N9 strain of avian influenza, so far confined to its developed eastern region, since announcing a week ago that the virus had been found in humans for the first time. There have been six deaths.

The education ministry ordered schools nationwide to “guarantee” the health of students and teachers against infectious disease, including H7N9.

They should educate students about the importance of washing hands, guarantee the safety of food served in canteens and strengthen monitoring of symptoms for illness, the ministry said in a statement.

In Shanghai, workers sprayed liquid disinfectant in classrooms to prepare for the return of pupils on Sunday after a holiday, local television showed. Sunday is officially a work day in China after the three-day Qingming Festival.

Shanghai — which reported two new cases on Saturday to bring the city’s total to eight, with four deaths — has banned live poultry trading and shut markets to try to halt the spread of the disease.

The Shanghai government said in a statement on its website Sunday that it had grounded nearly two million carrier pigeons and banned all races. Raising pigeons and songbirds is a popular hobby in China.

The city has also banned the sale of wild birds as pets, blocked public access to bird exhibitions at the city zoo and captured pigeons at city parks, the Shanghai Daily newspaper reported Sunday.

The nearby city of Nanjing has closed markets selling live poultry to its more than eight million residents, while Hangzhou culled poultry after discovering infected quail at a market.

In a strongly worded editorial on Sunday, the state-backed Global Times newspaper said the country’s “intense” farming methods heightened the risk of deadly diseases crossing from animals to humans.

“In China’s southern and eastern coastal areas, agriculture, especially animal husbandry, has become more intense and populations more dense,” said the English-language edition of the paper.

“There is greater chance of contact between humans and animals and subsequent diseases. Local authorities have to develop disease prevention and control methods to match this situation, but this is a weak spot in the country’s overall development.”

It called for higher standards in the agricultural industry and more balanced development, instead of a narrow focus on rapid economic growth.

Last month more than 16,000 dead pigs were found floating in a Shanghai river after being discarded by farmers upstream, casting a spotlight on China’s poorly regulated agricultural industry.

Chinese authorities, which have confirmed H7N9 in poultry, repeated Saturday there was no evidence of human-to-human transmission of the virus, a conclusion previously echoed by the World Health Organisation.

Experts have expressed concern about the wide geographical spread of human cases.

Taiwan has two possible cases of H7N9 involving people who travelled to the affected area in mainland China, now awaiting confirmation by medical tests, the island’s Centers for Disease Control said Sunday.

Taiwan, which has close travel links with mainland China, also said it had sent two health experts to Shanghai to get information on H7N9.

State media has reported the government had sought to improve transparency on the disease after being accused of covering up the 2003 outbreak of Severe Acute Respiratory Syndrome (SARS), which killed about 800 people globally.