Estimated global incidence of Japanese encephalitis: a systematic review
Grant L Campbell, Susan L Hills, Marc Fischer, Julie A Jacobson, Charles H Hoke, Joachim M Hombach, Anthony A Marfin, Tom Solomon, Theodore F Tsai, Vivien D Tsu & Amy S Ginsburg
Volume 89, Number 10, October 2011, 766-774E
Table 2. Summary of the 12 primary references used to estimate the incidence of Japanese encephalitis (JE) in Asia, by incidence group
||Study period||Study area||Study age group||Estimated study population||Estimated annual incidencea||Relative quality of study data|
|A||Japan||Arai et al. (2008)
||Routine (passive) national surveillance||53||100||1992–2004 (13 years)||Entire country||All||126.4 million (approx. mid-interval population)||0.003||Medium-quality data from national surveillance system based on physician reports of laboratory-confirmed cases; caveats include that laboratory methods used have evolved over time.|
|Hashimoto et al. (2007)
||Routine (passive) national surveillance||33||100||2000–2005 (6 years)||Entire country||All||126.55 million||0.004||Medium-quality data from national surveillance, based on laboratory confirmation of physician-reported, clinically suspected cases.|
|C1||China||Yin et al. (2010)
||Multiple hospital-based surveillance||121||100||Apr. 2007 to Sept. 2008 (17 months) or Sept. 2006 to Sept. 2008 (25 months), depending on prefecture||Guigang prefecture, Guangxi province; Yichang prefecture, Hubei province; Jinan prefecture, Shandong province||All||14.13 million||0.6b||Medium-quality data from 6 carefully selected sentinel hospitals in each prefecture; caveats include that not all hospitals in each prefecture were included.|
|Xufang et al. (2010)
||Multiple hospital-based surveillance||1609||75||2006 (1 year)c||Guizhou province||All||37.6 million||4.3||Medium-quality data; all hospitals in the province were included in surveillance, but samples were unavailable for testing in 25% (455/1837) of clinically suspected cases, so incidence estimate was adjusted upward, based on seropositivity rate among those tested.|
|C2||China||Yin et al. (2010)
||Multiple hospital-based surveillance||18||100||Apr. 2007 to Sept. 2008 (17 months)||Shijiazhuang prefecture, Hebei province||All||5.06 million||0.01d||See above.|
|D||Cambodia||Touch et al. (2009)
||Multiple hospital-based surveillance||583e||19||2007 (1 year)||Entire country||0–14 years||5.25 million||11.1||Medium-quality data from 6 carefully selected sentinel hospitals distributed throughout the country.|
|Indonesia||Kari et al. (2006)
||Multiple hospital- and clinic-based enhanced (active) surveillance||90||100||July 2001 to Dec. 2003 (2.5 years)||Bali province||0–11 years||599 120||6.0||High-quality data; all health care facilities in the province providing care for the study population were included in active surveillance system.|
|Thailand||Hoke et al. (1988)
||Vaccine trial; enhanced (active) local public health surveillance||11||100||1985–1986 (2 years)||Kampangphet province||1–14 years||21 516||25.6||High-quality data; all health care facilities in the province providing care for the study population were included in active surveillance system.|
|F||Nepal||Partridge et al. (2007)
||Multiple hospital-based surveillance||225||(100)||2006 (1 year)||Terai & Inner Terai districts (n = 24)||All||12.46 milliong||1.8||Medium-quality data from national surveillance system, based on laboratory confirmation of clinically suspected cases using an incomplete network of 93 hospitals and clinics; caveats include that specimens for laboratory testing were unavailable in 16% of clinically suspected cases, with no adjustment for this potential source of underdiagnosis.|
|Wierzba et al. (2008)
||Multiple hospital-based surveillance||951||100||May 2004 to Apr. 2006 (2 years)||Terai & Inner Terai districts (n = 24)||All||12.46 milliong||3.8||Medium-quality data from national surveillance system, based on laboratory confirmation of clinically suspected cases using an incomplete network of 64 hospitals; caveats include that specimens for laboratory testing were unavailable in 31% of clinically suspected cases, with no adjustment for this potential source of underdiagnosis.|
|G||Bangladesh||Paul et al. (in press)
||Multiple hospital-based surveillance||472d||8||Oct. 2007 to Dec. 2008 (15 months)||Bagerhat, Chittagong, Cox's Bazar, Jessore, Jhenaidah, Khulna, Naogaon, Narail, Nawabganj, Rajshahi, & Satkhira districts||All||27.5 million||1.4d||Relatively lower quality data because incidence was not directly measured, but rather extrapolated retrospectively from hospitalized, laboratory-confirmed cases to non-hospitalized, clinically suspected but laboratory-untested patients.|
|Nepal||Partridge et al. (2007)
||Multiple hospital-based surveillance||67||100||2006 (1 year)||Mountain and hill (non-Terai) districts (n = 51)||All||10.69 milliong||0.6||See above.|
|Wierzba et al. (2008)
||Multiple hospital-based surveillance||84||100||May 2004 to Apr. 2006 (2 years)||Mountain and hill (non-Terai) districts (n = 51)||All||10.69 milliong||0.4||See above.|
|Bhattachan et al. (2009)
||Multiple hospital-based surveillance||90||100||2007 (1 year)||Mountain and hill (non-Terai) districts (n = 51)||All||10.69 milliong||0.8||Medium-quality data from national surveillance system, based on laboratory confirmation of clinically suspected cases using an incomplete network of hospitals; specimens for laboratory testing were available in 96% of clinically suspected cases.|
|H||Malaysia||Wong et al. (2008)
||Single hospital-based surveillance||49||100||July 2001–2006 (post-vaccine programme) (5.5 years)||Sibu Hospital, Sarawak state||All||600 000 (in catchment area)||1.5||Medium-quality data from a single, central, large, sentinel hospital; caveats include that incidence estimates were apparently based on the assumption that 100% of JE cases in this hospital’s catchment area would present to this hospital, and that none from outside the catchment area would do so.|
IG. incidence group.
a Per 100 000.
b Weighted average of results from all three prefectures (using raw incidence data, as data used in their adjustment of incidence rates were not provided).
c April to November, but because this timeframe brackets the JE transmission season in the region, 1 year was used.
d Using raw incidence data, as data used in their adjustment of incidence rates were not provided.
e 100% of study cases were laboratory-confirmed; the study's authors then extrapolated their results to a larger geographic area, proportionate to the total number of acute encephalitis syndrome cases reported.
f These historical, pre-vaccination-era data from Thailand were used, in part, to estimate incidence in Incidence Group D, but present-day Thailand was included in Incidence Group H.
g 2001 census data.