Epidemic hysteria following the National School Deworming Day, Zamboanga Peninsula, Philippines, 2015


  • Johnette Agpoon Peñas Department of Health, Philippines
  • Vikki Carr de los Reyes Department of Health, Philippines
  • Ma. Nemia Sucaldito Department of Health, Philippines
  • Julius Erving Ballera Department of Health, Philippines
  • Herdie Hizon Department of Health, Philippines
  • Rio Magpantay Department of Health, Philippines
  • Vicente Belizario Jr Department of Health, Philippines
  • Kenneth Hartigan-Go Department of Health, Philippines




Introduction: In July 2015, the Philippines conducted a school-based mass drug administration using albendazole for soil-transmitted helminths infection. Reports of adverse events were subsequently made through the event-based surveillance system, mostly from the Zamboanga Peninsula on the island of Mindanao. A team from the Epidemiology Bureau investigated the reports of adverse events following mass drug administration (AEFMDA).

Methods: Five schools were identified for the investigation which comprised an unmatched case-control study, key informant interviews and laboratory examinations. AEFMDA cases were students who had sudden onset of abdominal pain, vomiting, diarrhoea, loss of consciousness, headache or dizziness within 24 hours after intake of deworming tablet; controls were healthy students who did not develop signs and symptoms after deworming.

Results: Most (85%) of the 7313 AEFMDA cases reported nationwide were from Zamboanga Peninsula. Most reports were made after rumours of deaths following deworming and of the use of expired drug were spread through the region. Many parents sent their children to hospital, even if asymptomatic. The case-control study found that being an AEFMDA case was associated with no history of previous deworming (odds ratio = 4.08, 95% confidence interval: 1.77–9.42).

Discussion: The investigation concluded that epidemic hysteria was the cause of the increased number of AEFMDA cases in the Zamboanga Peninsula. The false information, aggravated by social media, caused panic and an increase in reporting. Some cases had no history of deworming, and they may not have been aware that albendazole is safe and that side-effects are expected. Risk communication before, during and after future national deworming programmes are recommended to prevent unnecessary reporting of AEFMDA.

Author Biography

Johnette Agpoon Peñas, Department of Health, Philippines

Field Epidemiology Training Program Fellow, 

Epidemiology Bureau, Department of Health, Philippines


Gyorkos T. The Effect of a Deworming Intervention to Improve Early Childhood Growth and Development in Resource-poor Areas [Internet]. US: CLinicalTrials.gov; 2014 [cited 2015 July 31]. Available from https://clinicaltrials.gov/ct2/show/NCT01314937

Department of Education. Dep.Ed Memorandum. Guidelines on the Implementation of National School Deworming Day. Philippines; 2015

Department of Health. Administrative Order No. 2015-0030. Guidelines on the Implementation of the National School Deworming day. Philippines; 2015.

World Bank Health-Nutrition-Population. School Deworming at a Glance [Internet]. US: the World Bank; n.d. [cited 2015 July 31]. Available from http://web.worldbank.org/archive/website01213/WEB/IMAGES/AAGDEWOR.PDF

World Health Organization. Preventive Chemotherapy in Human Helminthiasis - Coordinated use of anthelminthic drugs in control interventions: a manual for health professionals and programme managers. Switzerland; 2006 [cited 2015 August 14]. Available from http://apps.who.int/iris/bitstream/10665/43545/1/9241547103_eng.pdf

World Health Organization. Assuring safety of preventive chemotherapy interventions for the control of neglected tropical diseases – Practical advice for National Programme managers on the prevention, detection and management of serious adverse events. Switzerland; 2011 [cited 2015, August 14]. Available from http://apps.who.int/iris/bitstream/10665/44683/1/9789241502191_eng.pdf

Jones TF. Mass Psychogenic Illness: Role of the Individual Physician. Am Fam Physician. 2000 Dec 15; 62 (12): 2649-53, 2655-6.

Boss LP. Epidemic Hysteria: A Review of the Published Literature. Epidemiologic Reviews. 1997; 19 (2): 233-243.

Govender, I. (2010). Mass hysteria among South African primary school learners in Kwa-Dukuza, KwaZulu-Natal. South African Family Practice, 52 (4), 318-321. Retrieved February 28, 2016, from http://www.tandfonline.com/doi/pdf/10.1080/20786204.2010.10873998

de Rochars MB, Kanjilal S, Direny AN, Radday J, Lafontant JG, Mathieu E, et al. The Leogane, Haiti demonstration project: decreased microfilaremia and program costs after three years of mass drug administration. Am J Trop Med Hyg. 2005 Nov; 73(5):888-94.

Kumar R, Khera A, Deb S, Chopra S, Jha P, Yadav D. National Deworming Day Operational Guidelines [Internet]. India: Child Health Division Ministry of Health and Family Welfare Government of India, 2016 [cited 2016 February 1]. Available from http://nrhm.gov.in/images/pdf/NDD-2016/Guidelines/Draft_NDD_2016_Operational_Guidelines.pdf

Njomo DN, Tomono N, Muhoho N, Mitsui Y, Josyline KC, Mwandawiro CS. The adverse effects of albendazole and praziquantel in mass drug administration by trained schoolteachers. African Journal of Health Sciences. 2010 July- December 2010; 17 (3-4): 10-14.

Njenga SM, Ng’ang’a PM, Mwanje MT, Bendera, FS, Bockarie MJ. A School-Based Cross-Sectional Survey of Adverse Events following Co-Administration of Albendazole and Praziquantel for Preventive Chemotherapy against Urogenital Schistosomiasis and Soil-Transmitted Helminthiasis in Kwale County, Kenya. PLoS One. 2014; 9(2): e88315. PubMed Central PMCID: PMC3919734.

Yasamy, M. T., Bahramnezhad, A. & Ziaaddini, H. (1999). La revue de Sante de la Mediterranee orientale, 5 (4), 710 – 716. Retrieved February 28, 2016, from http://apps.who.int/iris/bitstream/10665/118758/1/emhj_1999_5_4_710_716.pdf

Clements, J. C. (2003). Mass Psychogenic Illness after Vaccination. Drug Safety, 2003, 26 (9), 599 – 604. Retrieved February 28, 2016, from ww.cdc.gov.tw/downloadfile.aspx?fid=3F444A294998490C

Dodoo, A, Adjie, S., Couper, M., Hugman, B. & Edwars, R. (2007). When rumors to mass deworming exercise derail. Fundacio Institut catala de Farmacologia, 370 (9586), 465 – 466. Retrieved February 28, 2016, from http://www.sietes.org/buscar/cita/80881

Bush LM and Perez MT. Noncholera Vibrio Infections [Internet]. USA: MSD Manual; 2014 [cited 2015 August 26]. Available from http://www.msdmanuals.com/professional/infectious-diseases/gram-negative-bacilli/noncholera-vibrio-infections

Right Diagnosis. Vibrio Mimicus Food Poisoning [Internet].US; 2015 [cited 2015 August 26]. Available from http://www.rightdiagnosis.com/v/vibrio_mimicus_food_poisoning/intro.htm



How to Cite

Peñas JA, de los Reyes VC, Sucaldito MN, Ballera JE, Hizon H, Magpantay R, Belizario Jr V, Hartigan-Go K. Epidemic hysteria following the National School Deworming Day, Zamboanga Peninsula, Philippines, 2015. Western Pac Surveill Response J [Internet]. 2018 Dec. 3 [cited 2023 Sep. 22];9(4). Available from: https://ojs.wpro.who.int/ojs/index.php/wpsar/article/view/538



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