On 30 October 2015, three students in Mukuju Primary Teacher’s College, Tororo district, died of suspected food poisoning after eating chapattis (locally made flat bread). We investigated this cluster of illness to identify the cause and recommend prevention measures. Using a standard case definition, we reviewed medical and police records and interviewed survivors, health workers, and police officers for case-finding and hypothesis generation. We tested the chapattis and flour for poisons. We identified 7 cases with 3 deaths (case-fatality ratio=43%). Clinical manifestations included mental confusion (100%), constricted pupils (43%), frothing of saliva (43%), and low blood pressure (43%). The epidemic curve indicated a point-source exposure. The majority (86%; 6/7) of the cases were men; the mean age was 24 (range: 20–32) years. The deceased ate more of the chapattis than the survivors. Autopsy findings were consistent with organophosphate poisoning. Lab analysis of the flour and the chapatti indicated organophosphate contamination. This cluster of food-poisoning was caused by eating chapatti made of flour contaminated with organophosphate pesticide. We recommended stricter control of pesticides in Tororo District and throughout Uganda.
Background: Organophosphate poisoning results from exposure to organophosphates (OPs) commonly insecticides, which leads to symptoms of visual disturbances, tightness in chest, wheezing due to bronchoconstriction, increased bronchial secretions, in- creased salivation, lacrimation, sweating, and urination [1]. The onset and severity of symptoms, whether acute or chronic, depends upon the specific chemical, the route of exposure, the dose, and the individual’s ability to degrade the compound [2]. OPs are one of the commonest causes of poisoning worldwide, and are frequently intentionally used in suicides and homicides [3]. There are around 1 million Organophosphate (OP) per year with several hundred thousand resulting in fatalities annually [3]. Unintentional OP has been caused by ingestion of contaminated flour or leafy vegetables [4, 5]. In some cases it is accidentally ingested by children. In Uganda it has been estimated that 1,250 – 2,500 deaths per year due to OP [6].
On 30th/10/2015, at about 16:00 hours 3 students of Mukuju Core Primary Teachers’ College (PTC) in Tororo District bought and ate chapatti from a local food vendor at Mukuju trading centre adjacent to the school. Within approximately 20 minutes, they developed profuse sweating,
foaming of saliva, confusion, vomiting and difficulty in breathing. After a short while, they vomited blood and had diarrhoea. Two of the students were rushed to Mukuju HC IV for first aid before referral to Tororo Hospital where they were pronounced dead on arrival. The third was taken straight to Tororo Hospital but also passed away. Four other people who had eaten chapatti from the same vendor and developed similar though milder symptoms have since recovered following treatment. The recovered people included a student, the chapatti vendor himself, a bodaboda rider and a salon operator in the fateful trading centre of Mukuju. Preliminary information suggested that all identified people with these symptoms had eaten chapatti from this particular vendor before developing symptoms. The vendor reported that he made the chapattis as he always did and started selling them. When one of the students came back complaining about a strange smell from the chapattis, he decided to taste the chapatti himself and soon developed similar symptoms. Having been alerted about this, the Ministry of Health sent out a team to characterize the clinical, lab and post-mortem details of the deceased and survivors in order to identify the cause and prevent any further risk of contamination.
Methods: We defined a suspected case as onset of foaming of saliva or low blood pressure or loss of consciousness or constrict- ed pupils in a resident of Mukuju from 24th/10/2015 onwards. A confirmed case was any suspected case with confirmed toxicological re- sults. We found cases systematically by reviewing all the information of the deaths and patients and creating a line list. We visited the nearby health centres and district hospitals to identify patients fitting the case definition. With the help of the school administrators we searched for any other students who may have suffered from similar symptoms and fit the case definition. We also used the help of Local Council chairmen to search for any new cases especially among people living near the chapatti vending area. Patients’ clinical records were reviewed. Postmortem results were followed up with Police to identify the cause of death. The Police Surgeon undertook postmor- tem and shipped samples for toxicological tests to the Government Chemist in Kampala. An environmental assessment of the chapatti vending business was carried out to assess for possible sources of contamination. Samples of the left over chapatti, baking flour, cooking oil and mixed chapatti pastry dough were also sent for toxicological testing
Results: Six of the seven people affected were male. The mean age was 24 years and the ages ranged between 20 and 32 years. Four were students of whom 3 died and one survived leading to a Case Fatality Rate (CFR) of 3/7 (43%). The characteristics of these cases are summarized in table 1 below. The 3 who passed away developed symptoms consistent with organophosphate poisoning while the survivors had similar but milder symptoms. They all developed dizziness within approximately 20 minutes of eating the chapatti. This was followed by profuse sweating, confusion and loss of consciousness. The salon operator who only tasted the baking flour used for making the chapatti reported that she felt dizzy almost immediately, and shortly after developed irritation in the throat. The Medical Superintendent of Tororo Hospital stated that as he attended to one of the students, he noticed a strange smell on the student. The student was in coma, had low blood pressure and his pupils were constricted. All the affected people lived in the same village close to the chapatti vendor’s place.
We therefore deduced that some organophosphate poison had been introduced into the flour used to make the chapattis during the after- noon hours, after the 1st batch of chapattis were made in the morning. The reasons supporting the conclusion were:
The chapatti vending place is just outside the school gate and students as well as several other community members usually bought chapatti from there. There was no history of movement by the affected persons outside the school compound by the affected students on the 30th/10/2015 or within the past week. We therefore deduced that some organophosphate poison had been introduced into the flour used to make the chapattis during the after- noon hours, after the 1st batch of chapattis
were made in the morning. The reasons supporting the conclusion were:
The sudden onset of symptoms similar to those expected in OP and recovery after prompt organophosphate poisoning management at
Tororo hospital strongly support OP The post-mortem and lab findings all confirmed organophosphate poisoning.
All cases/deaths had eaten chapatti from this one vendor on that afternoon, indicating a point source exposure.
All cases had eaten lunch with other people (fellow students or family members) and were fine before eating the chapatti. This eliminates any possibility of having been poisoned prior to eating the chapatti. -People who had eaten chapatti from the same vendor in the morning had not developed any symptoms suggesting that the poison was introduced sometime in the afternoon.
-The 3 students who died had eaten a whole chapatti each while their colleague who survived had only eaten a portion of a chapatti before getting concerned about its smell. This demonstrated a dose response relationship.
There were no new cases from the time the chapatti business was banned.
Samples of the chapatti and flour tested from the National Analytical Laboratory (NAL) in Kampala were positive for the organophosphate pesticide Malathion. Post-mortems performed at Mbale Regional Referral Hospital showed results consistent with organophosphate.
There were no lab tests conducted on any of the patients and no specimens had been collected by the hospital.
At the time of the investigation, there were rumours in the village that the poison might be the chemicals used for Indoor Residual Spraying (IRS), an activity that was being conducted by the Ministry of Health at the time
Discussion and public health actions taken: This cluster of food poisoning was caused by consumption of chapatti baked using flour contaminated by organophosphate powder. Several cases of organophosphate poisoning caused by contaminated flour have been reported in the past [4]. On banning of chapatti vending in the area, the cases ceased immediately. We recommended stricter control of pesticides in Tororo and the whole of Uganda. Due to rumours in Mukuju town that the chemicals implicated might be IRS chemicals, community members were reassured by the district health officials that the chemicals used for IRS were tightly protected and were not the ones implicated. This prevented community- wide resentment of the IRS program that was ongoing at the time. We also noted that delays in early recognition of symptoms and prompt referral may have worsened the prognosis of the patients who died. The health workers of Mukuju HCIV were therefore briefed on the importance of early referral of patients in such scenarios. We explained to the health workers that early recognition of such life threatening conditions and prompt referral can greatly improve the chances of survival of such patients.
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