Epidemiologic investigation of a cluster of deaths due to eating fried rice balls intentionally tainted with Quinalphos, Sironko District, Uganda, a case series, 2017

Abstract

Background: Quinalphos is an organophosphate chemical chiefly used as a pesticide. On 13 November 2017, a cluster of unexplained deaths was reported in Village X, Sironko District, Eastern Uganda. We investigated to identify the scope and exposures for the cluster of deaths, and recommend control-measures. Case Presentation: We defined a suspected case as acute onset from 1-11 November 2017 of abdominal pain plus ≥1 of the following: vomiting, nasal bleeding, sweating, confusion, convulsion, loss of consciousness in a Village X resident. A confirmed case was a suspected case with a positive toxicological test of quinalphos by liquid chromatography. We reviewed clinical records and conducted active community case-finding. We investigated the exposure histories of case-patients, and inspected their homes for potential exposures. We identified 4 cases (including 1 confirmed) from a single household. The age range was six to fifty-two years; attack rate: 50%, 4/8, and case fatality rate: ¾ 75%. Symptoms included abdominal pain (100%), vomiting (75%), self-reported fever (50%), confusion (25%), convulsion (25%), loss of consciousness (25%), nasal bleeding (25%). Of the 4 case-patients, 3 had onset at 09:00hours and 1 at 19:00hours on 9 November 2017. The 4 case-patients shared 5 “bolingos” (fried rice balls) at 14:00hours, which had been given to case-patient A, a primary two level pupil (equivalent to the second grade in the US system) by an unknown person on her way home from school on 8 November. Case-patient A ate 1 bolingo and died within 35 hours, case-patient B ate 2 bolingos and died within 27 hours, case-patient D ate 1½ bolingo and died in 45 hours, case-patient C ate ½ bolingo, developed mild symptoms and survived. Additionally, 8 chickens also ate crumbs of the bolingo and died. A blood specimen of the lone survivor tested positive for quinalphos. After reading our report, police conducted a criminal investigation and found that the affected family had land disputes with a neighbour. One man was arrested and is awaiting trial. Conclusion: This fatal food-poisoning cluster of deaths was caused by eating bolingos (fried rice balls) intentionally tainted with quinalphos. We recommended strict control of pesticides, assessment of availability and use of pesticides in communities, and re-orientation of clinicians on case-presentation and management of organophosphate poisoning.