Sudanese doctors and aid workers are urging the government to declare a state of emergency over a cholera outbreak and delay the start of the school year, which began Sunday.
The disease, which is passed through contaminated water, has surfaced in five states, including the capital, Khartoum.
The U.S. Embassy said last month that fatalities had been confirmed, and Egypt has begun screening passengers from Sudan at Cairo's international airport.
Some 22,000 cases of acute watery diarrhea have led to at least 700 fatalities since May 20, said Hossam al-Amin al-Badawi, of the Central Committee of Sudanese Doctors, adding that it is most likely cholera, but the government refuses to test for it.
Doctors say cholera, a bacterial infection linked to contaminated food or water, has surfaced in the states of Khartoum, Al-Jazeera, Sennar, White Nile and North Kordofan, and are urging the government to seek international aid.
The fast-developing, highly contagious infection can spread in areas without clean drinking water or with poor sanitation. If left untreated, it can cause death from dehydration.
Sudan's official news agency SUNA meanwhile announced the opening of the school year, saying that authorities had the outbreak of "acute watery diarrhea" under control.
Activists and the opposition say President Omar al-Bashir's government refuses to acknowledge the cholera outbreak because it would reveal failures in the country's crumbling health system, where corruption is rife.
Neighboring South Sudan is grappling with the "the longest, most widespread and most deadly cholera outbreak" since the it won independence in 2011, according to the U.N. Since the outbreak began a year ago, over 11,000 cases have been reported, including at least 190 deaths, according to the World Health Organization and South Sudan's government.