There are 55 nationally recognized minorities in China, comprising just less than 9% of China’s total population. The five largest ethnic minority groups are Zhuang, Manchu, Moslems or Hui, Miao, and Uygur or Weiwu’er. Chinese minority groups are mainly distributed in the mountain area. In the 1950s, five provinces with large minority populations were designated as autonomous minority nationality regions: Xinjiang, Inner-Mongolia, Tibet, Ningxia, and Guangxi. Genetic backgrounds, customs, culture, and food consumption among ethnic minority groups are different. In the term of the health status of Chinese ethnic minorities, using the China Health and Nutrition Survey data collected during 1989-2006, Ouyang and Pinstrup-Andersen (2012) found negative and significant differences between minority and Han Chinese in a set of anthropometric measures for people of all age groups [1] .

Here, prior studies are collected to address the insight and understanding of the ethnic difference of disease prevalence in rural China. It also aims to describe knowledge and practices of the disease prevention in ethnic rural China.

The number and level of evidence of peer-reviewed papers and published ethnic differences of disease prevalence is outlined. See Table 1. The search strategy identified 9 peer-reviewed descriptive studies in the past 10 years. It is clear that the available literature is largely low level evidence, in line with the nature of previous research efforts.

Complementally, in a cross-sectional survey, Li, et al. (2012) found ethnic groups living in Xinjiang had striking differences in cardiovascular disease risk factors (CRFs; hypertension, obesity, diabetes, dyslipidemia, smoking) [12] . In Hainan, the prevalence of asthma in the Li ethnic group was 3.38%, much higher than the national average level in China. Aging, agriculture industry (the rubber industry in particular), rural residence, family history of asthma, history of allergies, cold air, inhalation of dust and irritant gases, smoking, domestic cooking fuel and living environment were associated with increased risk of asthma [13] . The prevalence of dyslipidemia, diabetes, and current smoking among older Korean Chinese with hypertension were 75.4%, 6.6%, and 23.1% respectively [14] .

In fact, not all diseases demonstrate ethnic difference. An investigation sponsored by Kunming Huaxia secondary specialized school in Yunnan confirmed there was no significant difference in deafness associated gene mutational spectrum and frequency between the Yunnan minority and Han patients [15] . Results from the review showed that there exist significant ethnic differences of disease prevalence in rural China. Next, the causes of ethnic differences need explanations.

Ethnic differences of disease prevalence mainly may be due to inequality in social status as for gender disparities [16] , inequality of access to health care services [17] , spatial inequality in health care [18] , differences in life expectancy [19] , regional health inequality [20] . Ouyang and Pinstrup-Andersen (2012) suggest that the economic development level of the province of residence is a major factor contributing to the health gap between minority and Han Chinese [1] .

Living environment and habits may be the second cause. Using data from the Chinese national survey on students’ physical fitness and health from 1985 to 2005, Ma, et al. (2009) find the physical functions and the athletic ability of the minority students in China had the advantages and characteristics, which might be related to their living environment and habits [21] . A cross-sectional survey conducted in rural areas of Yunnan Province, China from 2010 to 2011 find individuals belonging to an ethnic minority had a lower probability of exposure to secondhand smoke and nicotine dependence [22] . Social selection and the costs of relative deprivation appear to be useful to the understanding of health inequality in rural China, though in a manner shaped by the particular social context [23] . Chen and Meltzer (2008) suggest that, among rural Chinese residents, increasing community average income and income inequality are positively associated with both obesity and hypertension [24] .

The third cause may be different responses to drugs from different ethnic groups in China. In an open label, parallel-group study, healthy volunteers (10 Hans, 10 Mongolians, 10 Uygurs, 10 Huis and 9 Koreans) of Chinese nationality received a single oral tablet dose of 15 mg midazolam. The results are midazolam maximum concentration (C(max)) was significantly lower in Mongolians than that in Hans, Uygurs, Huis and Koreans (74.9 ± 33.7, 103.1 ± 26.4, 124.8 ± 50.0, 130.0 ± 38.3 and 189.0 ± 82.1 μg/L, respectively). Midazolam terminal half-life (t(1/2z)) were 3.0 ± 0.8, 2.2 ± 0.7, 1.9 ± 0.7, 3.5 ± 1.9, 3.8 ± 2.3 h for Hans, Mongolians, Uygurs, Huis and Koreans, respectively [25] .

The fourth cause may be ethnic factors. Innate factor is mainly concerned with heredity and race. A study aimed to explore the association between HLA-DRB1 alleles and anti-neutrophil cytoplasmic antibodies among Uyghur and Han patients with ulcerative colitis in China finds Genetic polymorphisms of the HLA-DRB1*08 and *13 may contribute to the clinical heterogeneity of ulcerative colitis between Uyghur and Han ulcerative colitis patients in China. In Uyghur ulcerative colitis patients, HLA-DRB1*13 may be correlated with anti-neu- trophil cytoplasmic antibodies positivity [26] . The gene frequencies of ADH2(2) and ALDH2(2) were lower in Tibetan and Mongolian populations than in Vietnamese, Han Chinese, and three Chinese minority populations [27] .

The fifth cause may be infant feeding. A longitudinal study of infant feeding practices with 1219 mothers (578 Han, 360 Uygur and 281 “other minority” mothers) report “exclusive breastfeeding” rates in the Han, Uygur and “other minority” groups at discharge were 78.0%, 34.5% and 83.1% respectively, at six months they had fallen to 4.8%, 0.4% and 16.8% respectively [28] . Breastfeeding is speculated to influence later-life health of an infant.

The sixthcause may be health literacy. An in-person interviews with 913 rural women aged 23 - 57 (57.5% Hui minorities/42.5% Han ethnicity) in Ningxia poor minority area revealed Hui minorities had 1.65 times higher rates of low health literacy and 1.22 and 1.25 times for pain/discomfort and anxiety/depression impairments, respectively. Low health literacy was associated with poor HRQoL, with a 23% increase in the prevalence of pain/discomfort impairments after adjusting for socio-demographics. This association was significant in the Hui group (PR = 1.30, 95% CI = 1.06 - 1.58) but not for the Han group (PR = 0.99, 95% CI = 0.76 - 1.30) [29] .

The final cause may be inequality in maternal health services utilization. A cross-sectional study from 10 provinces in rural Western China in 2005 reported that Han ethnicity woman, particularly in conjunction with high school education and rich wealth status, was the main contributor to inequality in maternal health services utilization. And it suggests that an effective way to reduce the inequality is not only to narrow the gap of income between the rich and poor, but focus education on ethnic minority woman in rural remote areas [30] .

The research effort undertaken aims to date on ethnic differences of disease prevalence in rural China. The ethnic differences of disease prevalence in China were produced due to socio-economic, ethnic, human, and policy- making causes. The key point is inequality distribution of health resources and poor primary health care services in rural and remote mountains.

The prevalence of diseases is high among ethnic minorities in rural China, representing an important health problem. More effort should be devoted to the study, prevention, and treatment of these diseases. Effective strategies are needed to reduce the incidence of diseases in this ethnic population. Public health should be more concerned with social policies and social determinants than with health services and disease control. Governments should make sure that high-quality health service can reach remote ethnic rural China. Zheng, et al. (2011) suggest policy-makers should attempt to improve economic development in less developed regions and to improve health policies and the public health systems that address the needs of everyone [19] . I also agree with Fang, et al. (2010) that investment in health resources can help China achieve and maintain equality in distribution of health [20] . In fact, primary health care plays a more important role than hospital services in reducing ethnic disparities in health. Strategies that can enhance public awareness of diseases and increase access to affordable medications are urgently needed, especially for poor, less educated individuals who belong to ethnic minorities. Ethnic-specific strategies should be developed to prevent disease in different ethnic groups, as ethnic villagers with diseases were not actually aware of their condition.

This study was funded by the “Wellbeing and quality of life of minority families migrating from rural to urban areas” sponsored by the Ministry of Education of China Humanities and Social Sciences Research Youth Project Fund (Project number:14YJC630042).