It's almost peak season for a deadly virus spread by ticks in China. In fact, the number of people affected by the disease called severe fever with thrombocytopenia syndrome (SFTS) has exploded since it was first reported in 2009.
Those afflicted with SFTS show symptoms such as fever, diarrhea, nausea, and swollen lymph nodes. Currently, no known cure exists.
Although global deaths from SFTS each year have been fewer than 200, the numbers of infected are growing.
The disease' incidence has increased dramatically in East Asia, with China reporting 2,600 cases in 2016 compared to only 71 in 2010, according to the journal Nature.
The virus that causes the disease was first identified in the rural areas of China's Hubei and Henan provinces, and later spread throughout the country and to neighboring S. Korea and Japan.
A Nature report shows that Chinese health authorities recorded over 5,000 confirmed cases from 2011 to 2016. Several factors contribute to the likelihood of being infected.
Immune function
One is occupation, as the majority of those affected are farmers who are more likely to come into contact with animals carrying Haemaphysalis longicornis ticks or engage in outdoor activity in tick-dense rural areas.
Another is age, as the elderly are particularly susceptible, possibly due to lower immune function. The median age of confirmed cases is 60 years or older.
Provinces in east or central China have reported the highest number of cases, such as Henan, Shandong and Hubei. However, the report's authors noted that certain provinces with higher prevalence had lower rates of death and they speculated that was because experienced physicians were able to identify the disease early on.
The peak months of the disease are May, June and July, according to the report.
To control the spread of the virus, the report's authors advise that people avoid areas with ticks, but if they must go, then wear light-colored clothing so that the ticks are easily visible. They also suggest that hospitals improve their capabilities to identify the disease in its early stages and measures be taken to control tick populations.
