Nat Commun: Scarlet fever has resurgent in China in the last decade, and air pollution is to blame?

On August 25, the latest issue of Nature Communications published a research paper entitled: Exposure to air pollution and scarlet fever resurgence in China: a six-year surveillance study, jointly completed by research institutions such as Sun Yat-sen University's School of Intelligent Engineering, the Zhejiang CDC, the China CENTER for Disease Control and Prevention, and the Taiwan Central Research Institute.
six-year study suggests that air pollution may be a major cause of China's scarlet fever resurgent! The researchers retrieved data on 655,039 cases of scarlet fever and 6 air pollutants nationwide and found that the increase in environmental pollutants NO2 and O3 was associated with an increase in scarlet fever incidence.
: Liu Shilan, Chen Enfu, Yu Zhi of Sun Yat-sen University, and Zhan Dachi of the Central Research Institute of Taiwan are the authors of this paper.
Scarlet fever is a disease caused by septic (alpha group) streptococcus, with symptoms and signs including sore throat, fever, headache, swollen lymph nodes, and characteristic rashes.
the disease most commonly occurs in children between the ages of 5 and 15, but adults can also be infected, with kindergartens, schools, factories, etc. being places with high scarlet fever.
scarlet fever symptoms most cases of scarlet fever are mild infections, with few fatal infections.
, however, the terrible thing about the disease is that it can develop serious sequelae, including kidney disease, rheumatoid heart disease and arthritis.
addition, scarlet fever can be transmitted through close contact, respiratory droplets (such as saliva or snot) or contaminants.
scarlet fever was Europe's worst killer in the 18th and 19th centuries.
the last century, however, the incidence of scarlet fever has declined significantly with the development of effective cures, improved living standards, improved sanitation and improved nutritional conditions.
, scarlet fever has made a comeback in recent years.
the incidence of scarlet fever has Chinese mainland in Asia, particularly in South Korea, South Korea and Hong Kong, and in Europe, particularly in the UK.
, however, the resurgent scarlet fever has become a global public health problem because there is no vaccine to prevent streptococcus infection.
2019, when the incidence of scarlet fever in China changed from 2004 to 2018, the World Health Organization (WHO) listed the top 10 threats to global health, with air pollution considered by the WHO to be the greatest environmental risk to health.
air pollution affects people's health in different ways, and a series of evidences suggest a positive correlation between exposure to air pollution and respiratory diseases.
Previously, a small number of studies had predicted that a small number of cases of scarlet fever might be associated with air pollution, but these studies focused only on specific regions or cities in China, or were based on a single scenario, so the results were diverse, fragmented and uncertain.
the study, researchers counted 655,039 cases of scarlet fever in China between 2004 and 2018, with an average annual incidence rate of 326 per 100,000 people.
note that the incidence of scarlet fever in China began to surge in 2011 and increased further in 2017 (5.37/100,000) and peaked in 2018 (5.67/100,000).
The National Scarlet Fever Annual Incidence Research Team also investigated the seasonal patterns of scarlet fever incidence in China, with scarlet fever peaking every six months nationwide, including the main peak in May-June and the secondary peak in November-December.
, scarlet fever is prevalent mainly in the north, northeast and northwest of China.
2013-2018 China's air pollution characteristics 2013-2018, the national average concentration of PM2.5 was 51.28 μg/m3, the average concentration of PM10 was 90.75 μg/m3, SO2 (sulfur dioxide) The average monthly concentration is 24.35 μg/m3, the average monthly concentration of NO2 (nitrogen dioxide) is 33.63 μg/m3, the average monthly concentration of CO (carbon monoxide) is 1.08μg/m3 and the average concentration of O3 (ozone) is 86 mg/m3 for 8 hours during the day.
, the average monthly concentrations of PM2.5 and PM10 are much higher than those of the China Guidelines II. levels published in 2018, while the monthly changes in atmospheric pollution concentrations have distinct seasonal characteristics.
peaks of PM2.5, PM10 and NO2 are mostly in December and January, while O3 peaks occur in May-August.
Descriptive statistics on scarlet fever cases and air pollution concentrations and weather conditions in China for 2013-2018 show that the average monthly concentrations of six air pollutants at high latitudes were significantly higher in high latitudes than in low latitudes between 2013 and 2018.
average annual concentrations of the six air pollutants vary widely, but increases are more pronounced in the north and west.
, the average monthly concentrations of PM2.5, PM10 and CO decreased significantly year by year, while the O3 values increased significantly, and NO2 began to show an upward trend in volatility in 2016 after a downward trend in 2013-2016.
Air pollutants and scarlet fever relationship research team used multiple distribution lag nonlinear models and metaregression models to analyze scarlet fever incidence data and air pollution data, they found a significant correlation between 4 of the 6 air pollutants and scarlet fever incidence, of which NO2 was the most correlated.
the average incidence of scarlet fever in 2011-2018 was twice as high as in 2004-2010 (4.40 vs. 1.91), and scarlet fever was associated with low to moderate correlations with NO2 (r s 0.21) and O3 (r s 0.11).
no2 and O3 in the air, the cumulative risk of a lag of 0 - 15 months is 1.06 (95% CI: 1.02-1.10) and 1.04 (95% CI: 1.01-1.07), respectively.
results suggest that long-term exposure to air pollution containing NO2 and O3 may be associated with an increase in scarlet fever incidence in China in recent years.
The Pearson correlation coefficient between air pollution concentration/weather conditions and scarlet fever incidence in China in 2013-2018 is noteworthy that NO2 in the air mainly comes from burning fossil fuels, especially vehicle fuels such as automobiles, trucks and buses.
ozone is mainly produced by the interaction of nitrogen oxides (NOx) and volatile organic compounds (VOCs) with sunlight, and of course, it is also associated with traffic-related exhaust emissions.
entering the 21st century, China's economy is booming, people's quality of life is getting better and people's car ownership per capita is getting higher and higher, which has also led to a surge in air pollutants such as NO2 and O3.
studies have shown that short- or long-term exposure to high concentrations of NO2 stimulates the airways of the human respiratory system and may increase susceptibleness to respiratory infections.
this means that vehicle-caused pollution emissions may be responsible for the increase in scarlet fever incidence in China in recent years! In summary, in this study, the team applied an ecological research design to study the relationship between long-term air pollution exposure, meteorological conditions, and scarlet fever incidence across China.
researchers assessed relative risks using a distributed lag nonlinear model (DLNM), layering them according to different air pollutants, meteorological factors, and high- and low-risk areas.
, the researchers assessed the effects of population and behavior, such as population density and school holidays, on scarlet fever incidence.
is also the first national study to look at the relationship between air pollution and a sudden rise in scarlet fever incidence in China, based on data from across the country, with a large population and the longest time span.
findings suggest that scarlet fever cases have increased dramatically since 2011 and that prolonged exposure to air containing NO2 and O3 is associated with a surge in scarlet fever.
, the incidence of scarlet fever also appears to be associated with school holidays, which are even lower during summer and winter holidays.
: "Our study encourages public health authorities to actively consider the risks of NO2 and O3 when fighting scarlet fever resurgent," the researchers said in the paper.
addition, school-based controls may be particularly important in controlling scarlet fever.
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