18 January 2000
Polio in China
The following case report is from the WHO Polio
The case was first reported to the County EPS in Geizi Township, Xunhua County, Haidong
Prefecture, Qinghai Province, on 13 October 1999, and reported to the Provincial EPS on
the following day. The case was born on 13 June 1998, had onset of paralysis on 12
October, after a day of fever on 11 October. The parents took the boy to a local private
clinic in a neighbouring township when a sudden onset of flaccid paralysis made him unable
to stand or walk (both of which he had been capable of before). Two stool samples were
taken, the first on 14 October and the second on 25 October. They were analyzed in the
provincial laboratory. Both samples yielded poliovirus isolates, which were later typed
and differentiated as P1 wild viruses at the national laboratory in Beijing. At the time
that the second sample was taken five contacts were sampled, one of which, a four year old
cousin of the infected child, was also positive for wild poliovirus. The case child was
unregistered and had received zero doses of polio vaccine.
The case belongs to the Sala minority group, a Muslim group of Turkic speaking people
whose ancestors migrated to Qinghai from the area of Turkmenistan about seven hundred
years ago. There are around 80 000 Sala in China, 60 000 in Qinghai Province (nearly all
of which live in Xunhua Sala Autonomous County) and nearly all of the remainder in
neighbouring Gansu Province. Adult male Sala travel widely as traders and workers, within
Qinghai province and outside to other provinces, including Gansu, Sichuan,Xinjiang, and
particularly Tibet, even as far as the border area with Nepal.
Neither the case nor the direct family reported a history of travel outside the county
in the two months prior to onset. No visit to the family by a traveler from outside the
county was reported to occur during the same period. However, the family, including the
case, attended a major festival of Sala people in the county capital during the period 25
to 28 September 1999. Up to 30 000 Sala are reported to have attended this gathering.
Despite intensive investigation in the area of the case, including searches of health
facilities, no evidence of wide-scale circulation of wild poliovirus has yet been found.
Surveillance quality including laboratory proficiency in Qinghai Province and in
neighbouring provinces is in general good. Indications are therefore that the virus has
been recently imported.
The Ministry of Health of China is actively collaborating with the global laboratory
network including CDC Atlanta, NIID Tokyo and the national laboratories in India. Initial
sequencing information on the wild poliovirus show a close similarity to viruses recently
circulating in India. The virus is significantly different from those that have been
circulating in China up to the last case in 1994. Further genomic sequencing work is
A combined MOH/WHO/UNICEF/JICA mission visited Qinghai Province from 20-25 December
1999 to review the response to the case. Initial case response immunization has been
carried out, achieving high coverage of the target group. Extensive additional activities
are planned, including large scale immunization across several provinces, intensified
surveillance, retrospective review of hospital records at all levels in several
provinces,and active search for cases of acute flaccid paralysis.