Health workers in Marsabit and NGOs are on high alert following an outbreak of malaria in North Horr constituency. The disease has claimed at least 23 lives in two weeks in that constituency alone.
But there are fears more residents could be suffering from the disease in their homes in other areas.
Health officials said tests carried out on 590 residents on Wednesday revealed that more than 70 % have malaria.
North Horr subcounty director of health Huko Halake on Wednesday said 424 of the 590 residents in Dukana tested positive for malaria.
It was reported that two dozen residents suffering from the disease are receiving treatment at various dispensaries in the subcounty.
The health official said the county government and humanitarian agencies have started supplying medicine to residents.
50,000 mosquito nets are being supplied to residents since the state has adequate anti-malaria drugs and assured residents there is no cause for alarm.
Blood samples collected from residents have been taken to the Kenya Medical Research Institute laboratories in Nairobi for further testing.