Bulletin of the World Health Organization

Paperless registration during survey enumerations and large oral cholera mass vaccination in Zanzibar, the United Republic of Tanzania

Mohammad Ali, Jaqueline L Deen, Ahmed Khatib, Godwin Enwere, Lorenz von Seidlein, Rita Reyburn, Said Mohammed Ali, Na Yoon Chang, Valérie Perroud, Frédérique Marodon, Abdul A Saleh, R Hashim, Anna Lena Lopez, James Beard, Benedikt N Ley, Kamala Thriemer, Mahesh K Puri, Binod Sah, Mohamed Saleh Jiddawi & John D Clemens


Field trials require extensive data preparation and complex logistics. The use of personal digital assistants (PDAs) can bypass many of the traditional steps that are necessary in a paper-based data entry system.


We programmed, designed and supervised the use of PDAs for a large survey enumeration and mass vaccination campaign.

Local setting

The project was implemented in Zanzibar in the United Republic of Tanzania. Zanzibar is composed of two main islands, Unguja and Pemba, where outbreaks of cholera have been reported since the 1970s.

Relevant changes

PDAs allowed us to digitize information at the initial point of contact with the respondents. Immediate response by the system in case of error helped ensure the quality and reliability of the data. PDAs provided quick data summaries that allowed subsequent research activities to be implemented in a timely fashion.

Lessons learnt

Portability, immediate recording and linking of information enhanced structure data collection in our study. PDAs could be more useful than paper-based systems for data collection in the field, especially in impoverished settings in developing countries.