Measles - a disease Beijing had intended to virtually eliminate by 2012 - is making a comeback as millions of migrant workers miss out on vaccinations.
Cases of measles on the mainland hit 11,089 in April compared to 2,070 in January, according to the health ministry. The total was almost as high - 10,563 - in May. In just the first five months of the year, the number of cases reached 35,677, surpassing the 27,646 cases for the whole of last year.
"The outbreak of measles is related to the lack of vaccination. The incidence of measles is likely to rise, mostly in adults, because China has such a large mobile population and many have missed their vaccinations," said Professor Cai Haodong, an expert in infectious diseases at Beijing Ditan Hospital.
There were 245 million migrant workers, accounting for 18 per cent of the population, at the end of last year, according to the National Bureau of Statistics. Low awareness among migrants of the need for vaccinations, in addition to the challenge for public health authorities of tracking the mobile population, are key reasons for much lower vaccination rates among migrants.
The Guangdong-based Information Times reported in April that according to Guangzhou's Centre for Disease Control and Prevention director Wang Ming , migrant children often failed to receive vaccinations on time, forcing public health workers to try to reach them.
In Beijing, more than 92 per cent of permanent residents' children have had shots, but in some areas of the capital with a high proportion of migrant workers, the rate is only 54.7 per cent, according to a survey published by the city health authorities.
Last year, 24 people died of the contagious viral disease characterised by fever and red spots on the skin. So far this year, 15 have died. Authorities had hoped to bring down the prevalence rate to just one case in every one million people by 2012. But even that year, when there was a record low number of cases, there were still more than 6,000 reported by the health authorities.
Amid warnings the number of cases is likely to keep on rising, doctors have urged the central government to push vaccination. In 2010, nearly 100 million children aged between eight months and 14 years were vaccinated in the mainland's biggest inoculation effort.
The 10-day campaign was in response to the World Health Organisation's call to combat measles in China.