This thing is lethal especially coz its a combination of two viruses. However i know Cimmyt In collaboration with KARI are actively trying to develop a variety that is resistant to the disease but that will definitely take some time.All in all pole Have you enquired from Kephis/KARI/kenya seed if they may have any tolerant varieties for your area?

The Kenya Plant Health Inspectorate Service (KEPHIS) has approved three new maize varieties that are resistant to the deadly necrosis disease
maize-disease-Kenya-KEPHISThe new maize varieties are resistant to necrosis disease.
The Tumaini 1 variety, also known as Type Wei 101, will soon be released to Kenyan farmers and has been deemed suitable to farmers in Bomet, Nakuru and Narok counties as well as areas in the lower eastern part of the East African country.
KEPHIS has bred the new variety in collaboration with the Kenya Agricultural Research Institute (KARI), the Global Maize Programme of the International Maize and Wheat Improvement Centres (CIMMYT) and the Africa Agricultural and Technology Foundation (AATF).
Three other highly tolerant varieties – Wei 108 and WM 1259 both from KARI and MZ 1202 from the Kenya Seed Company (KSC) – have also been undergoing further testing.
"Tests are at advanced stage," said KEPHIS managing director Dr James Onsando. "We are fast-tracking the process and the varieties could be released before the end of the year."

Thanks @Marie & @Small. ...meant Duma. We observed that the Kienyenji type somehow resisted while this hybrid type was all taken down in a two acre farm.Things are bad.