Species of virus
Rice black-streaked dwarf virus (RBSDV) is a plant pathogenic virus of the family Reoviridae, causing diseases in rice and maize, causing significant crop losses in East Asian countries.
Not to be confused with the Southern Rice Black-streaked Dwarf Virus, as this virus does not contain the same insect vectors, and is an entirely separate virus. The sole transmitter of RBSDV is the Laodelphax striatellus, aka the small brown planthopper (SBPH).
Affected areas.
RBSDV primarily affects regions in East and Southeast Asia, particularly countries such as China, Vietnam, South Korea, Japan, and Thailand. Affected countries are dependent on the migration patterns of L. striatellus.
Preventative actions.
China has been significantly affected by RBSDV and has implemented various control measures, such as seedbed coverage, chemical seed treatments, and chemical spraying of seedlings. Researchers in China are also actively screening for effective anti-RSBDV drugs and investigating further preventative measures (2013). 
While specific measures may not be detailed, we can assume that heavily impacted countries such as Vietnam are taking similar actions.
References.
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