On Friday, September 28, 2018, the 7.4 Richter Scale earthquake hit Central Sulawesi and was followed by a tsunami. Within a month after the unpredictable earthquake and tsunami, a 773 aftershock earthquake was noted. These events took a major toll on the population in the affected areas. 2,086 people died and more than four thousand people were injured. 1.373 people went missing and 206.494 were evacuated. Surveillance data from November 4, 2018, to October 24, 2018, showed that an increased number of illnesses such as diarrhea was the second leading reported cases. Data showed that the number of diarrhea cases was 3.350 with two peaks of epidemic curves on October 10 and 22, 2018.

To verify the diarrhea outbreak after the tsunami in Palu, Donggala, and Sigi District.

Verification of medical records at six selected primary healthcare institutions with the highest number of cases of diarrhea.

A pseudo-epidemic of diarrhea occurred. A high number of diarrhea cases occurred due to double reporting and misdiagnosed cases. Investigation reports showed that liquid defecation was considered diarrhea even though it occurred less than three times a day. The follow-up activity was contacting data entry managers to revise data, disseminate findings during the daily meeting of the health-related officers, and broadcasting findings through a WhatsApp group of provincial and district surveillance officers. Post-investigation, the number of diarrhea incidences was lower and the peak was not shown on the epidemic curve. It can be interpreted that a diarrhea outbreak did not occur in the tsunami-affected area in the Palu, Donggala, and Sigi districts.

During a time of disaster, a chaotic situation led to improper data collection. Data verification should be conducted to assure the validity of reported data.