Some 47 people have died since the first outbreak in March, said Dr. Omar Mohammed Suleiman of the Ministry of Health and Social Welfare in Zanzibar, blaming poor sanitation in rural areas on the tropical island.
Several villages have been quarantined in the north of the island to prevent the disease spreading.
Last month the government closed cholera camps it had set up to combat the disease believing the outbreak had been contained.
Although the latest outbreak is around 20 kilometers from the nearest tourist areas, health officials said they feared visitors would be discouraged from traveling to Zanzibar.
Last year some 500,000 tourists traveled to Zanzibar, bringing in vital foreign currency to the Indian Ocean island, the AP reports.
Cholera is transmitted through contaminated water and is linked to poor hygiene, overcrowding and bad sanitation. Symptoms include diarrhea and vomiting, which can kill unless treated quickly.
A 1997 outbreak killed 124 people and sickened 1,100 in Zanzibar, which has a population of 1 million.
Russian President Vladimir Putin got the West worried again by signing Decree No. 915. The news did not produce any public effect in Russia