This is despite samples being taken to Kenya Medical Research Institute (Kemri) for further investigations three weeks ago.
At least 500 students were taken ill over suspected food poisoning forcing the Ministry of Education to shut down the school indefinitely after two students died.
Julian Mujema, a teacher who served as the boarding mistress at the school is the latest casualty of the mysterious illness after she succumbed to multiple organ failure at the LifeCare Specialty Hospital in Eldoret.
"Mujema was brought to the hospital on Wednesday night with acute kidney and liver failure and vaginal bleeding. She had lost a lot of blood and the pressure was very low," Dr Rahul Koshek, the head of the facility's ICU department.
Dr Koshek said that at the time the deceased was admitted, she was in a critical condition.
Mujama was taken ill on April 2 and admitted at a local hospital in Kakamega town from where her condition was being managed.
The medics at LifeCare hospital aver that the symptoms being exhibited by patients coming in from Mukumu Girls are very rare and need urgent interventions from health researchers.
At the same hospital, a student has also been admitted fighting for her life in critical condition.
What is puzzling the doctors is that those who have succumbed are exhibiting newer symptoms ranging from kidney and liver failure, hemorrhage, diarrhoea, and fluctuating fever.
The death of the boarding mistress comes just three days after a form four student, Diana Munyasia, died while undergoing treatment at the Kakamega County Teaching and Referral Hospital.
Munyasia, 18, was admitted to the hospital's Intensive Care Unit (ICU) last Sunday while in critical condition.
"When she came home for the half-term break last month, she was weak and sickly. We have taken her to different hospitals hoping that she will get well but all was in vain," said Rasoha Mambili, her mother.
She added: "My daughter had diarrhoea and was seriously vomiting. She had vaginal bleeding and her urine was like tea-coloured urine. At the hospital, we were told that she died from multiple organ failure. Her kidney and lungs had collapsed,"
Wendy Oyugi and Miriam Namachanja who were in Form One and Form Two respectively were the first causality of the mysterious illness.
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Titus Ngulungu, a government pathologist who conducted a postmortem on Wendy Oyugi's body at Umash funeral home in Nakuru said that she had an inflammation in her stomach that caused the hemorrhage.
Mukumu Girls Alumnae Association in a press release sent to newsrooms has accused the school management of speaking from both sides of the mouth despite the issue at hand being a matter of grave concern.
They have accused school principal Fridah Ndolo of not communicating what's happening and at the same time sideling the board chairman Dr Josphat Kwasira when making key decisions affecting the running of the school.
"This is not the first time the school is in the news for the wrong reasons. Management of this incident leaves a lot to be desired," said chairperson Enid Busolo.