Today, Egypt's Shi‘ites are a tiny percentage; 1% of the population is sometimes heard. They were much harassed under Mubarak, mostly by State Security which suspected them of being a potential pro-Iranian fifth column. Some are indeed of Iranian or Pakistani origin, but there are indigenous Shi‘ites as well. Some of the often quoted activists are, in fact, converts from Sunnism.
|Shahada on the Bab al-Nasr|
Sayyida Zaynab, being honored by the celebrants described at the link, was the Prophet's granddaughter, daughter of ‘Ali and Fatima, sister of Imams Hasan and Hussein. She is also one of the "patron saints" of Cairo, and her tomb there is a popular place of pilgrimage, especially for women. Her birthday is one of he great mulids or saint's days in Cairo, celebrated by Sunnis and marked by the Sufi orders, though explicitly Shi‘ite observations have been suppressed. (Like certain other highly venerated saints, Muslim as well as Christian, she is too popular to be buried in only one place. She also has a highly visited tomb in Damascus. Her brother, Imam Hussein, is held by most Shi‘ites to be buried in Karbala' in Iraq, but the Sayyidna Hussein mosque in Cairo says they have his head. Christians should not be cynical: do you know how many places have John the Baptist's head?)
In fact, Cairo's most popular "patron saints" are almost all of them Shi‘ite figures: Sayyidna Hussein, mentioned already, though today his celebrations are primarily an outlet for the Sufi orders; Sayyida Zaynab; her half-sister (daughter of ‘Ali by a wife other than Fatima), Sayyida Ruqayya (who, like her sister, is also buried in Damascus); and Sayyida Nafisa, a great-great-great-granddaughter of the Prophet who, so far as I know, is only buried in Cairo.
Ironically, of Cairo's great city patron saints, all but one are highly venerated descendants of the Prophet and thus Shi‘a saints as well. The one unambiguously Sunni patron saint is Imam al-Shafi‘i, founder of one of the four great legal schools of Sunni Islam. His tomb is also a major pilgrimage site. The only irony there is that the Shafi‘i legal school does not wholly approve of venerating saints' tombs and holding pilgrimages.
An oddity: Anwar Sadat in his last years allowed a modern Indian Isma‘ili group to refurbish the Fatimid Mosque of Al-Hakim, creating a Shi‘ite (but not a "Twelver") presence in the ancient Fatimid city.
Despite some heated propaganda when the Mubarak regime was denouncing Iran, there is little likelihood of a major rebirth of Shi‘ism in Egypt. But the bits and pieces of its history still play a role in the daily popular (and Sunni) religious life of the city, especially for the popular city saints.