We assessed the trends and spatial distribution of organophosphate poisoning admissions incidence and deaths in Uganda, 2017─2022. The incidence of organophosphate poisoning admissions declined over the study period with an overall CFR of4.2%. Males, children < 5 years, and residents of Ankole Region were the most affected. Two districts (Kiruhura and Bukwo) had the highest incidences throughout the study period.
The incidence of organophosphate poisoning admissions declined throughout the study period. Since 2014, Uganda has implemented periodic public awareness campaigns about safe use of pesticides for small-holder farmers and pesticide dealers [21]. These campaigns have included sensitization about responsible handling to reduce risk of poisoning and environmental pollution. Additional campaigns targeting government pesticide regulators, non-governmental organisations, and media have also been implemented to address the dangers of organophosphate poisoning [22]. These have included information about safe handling and use of pesticides and sensitization about banned and counterfeit pesticides. Similar health education and hazard assessment programs have been shown to have contributed to a reduction in organophosphate incidences amongst livestock farmers in Zambia [23]. Additionally, in 2008, Uganda ratified the Rotterdam Convention, which banned the importation and use of highly toxic pesticides [24]; Uganda has also implemented the Agricultural Chemical Control Act to use less toxic pesticides [25]. Together, these may be contributing to the reduction in the incidence of organophosphate poisonings. To continue this decline, it is important to monitor and strengthen these interventions.
The overall CFR was 4.2%. This is lower than the CFR in two other Uganda studies on organophosphate poisonings done in hospital emergency centres in Uganda in 2022 (18%; 11/61) and 2018 (7.3%; 7/96) [26, 27]. Mortality in organophosphate poisoning depends on the route of administration, the exposure dose, obtaining early diagnosis, and availability of appropriate medical care [28, 29]. It is possible that since patients included in this study were inpatients, they may have had access to appropriate treatment, including activated charcoal and atropine, which are known to decrease mortality after organophosphate ingestion [3, 30]. High CFRs were reported in a retrospective study; CFR = 7.8% (51/656) and a prospective study CFR = 5.6% (13/230) conducted in Tanzania[31]. This was attributed to challenges in clinical management of patients due to lack of specific details on the OP chemicals responsible for poisoning during hospital care. Ensuring that hospitals are stocked with equipment and antidotes for organophosphate could help further reduce the mortality associated with this exposure.
Males in our study were more affected than females. In Uganda, men are more involved than women in agricultural activities which involve spraying of pesticides and these put them at high risk of occupational exposure [32–34]. Occupational exposures can occur through unintentional ingestion, inhalation, and skin and eye contact [35]. Studies in India have similarly identified higher incidence of organophosphate poisoning among men than women [36, 37]. There is need to sensitize the public, especially men involved in agricultural work, about the importance of wearing personal protective gear like gloves, boots, and gloves during pesticide application.
Children below 5 years were more affected by organophosphate poisoning than persons who were above 5 years. Studies in Uganda and China in 2017 also found that children were more affected than adults [38–40]. Globally, most organophosphate poisoning cases in children are accidental and occur after they ingest pesticide that was poorly stored in households [41, 42]. In Uganda, there is often poor storage practices of pesticides in the households [38], leading to easy access by children. The exploratory and inquisitive behaviour together with frequent hand-mouth movements puts children at a risk of pesticide poisoning through the oral route [43]. Interventions that facilitate further reduction in the incidence of organophosphate poisoning amongst children are advisable. For instance, care takers to safely keep pesticides away from reach of children and packaging pesticides in containers that cannot easily be breached by children.
Residents in Ankole Region were the most affected by organophosphate poisonings. Additionally, the incidences of Kiruhura and Bukwo districts remained high every year during the study period. Ankole Region (which includes Kiruhura District) is one of several regions engaged in both agriculture and livestock farming [44]. This region implements the intensive mixed farming model of growing of crops (banana-coffee) and rearing of cattle unlike other regions which exclusively apply either the crops (banana, coffee, millet, tea, cotton, millet, maize and cassava) or rearing animals (cattle-goats) only models[45]. This may lead to increased circulation of organophosphate agro-chemicals in Ankole Region as opposed to other regions. Additionally, poor handling likely plays a role. A study in Ankole Region about the usage of pesticides amongst dairy livestock farmers revealed that most farmers handled highly toxic agrochemicals without following proper instructions or having personal protective equipment [46]. However, similar data are not available for other regions. Like Kiruhura District, Bukwo District is also heavily involved in agriculture and livestock farming [47, 48]. Further investigation is needed to understand the reason for persistently elevated levels of organophosphate poisoning in these districts, compared to other districts with similarly agricultural and livestock-based economies.
Higher-level admitting health facilities recorded a higher CFR compared to lower-level health facilities. Lower-level health facilities (which act as the first point of care) may not have the staff, stock, or equipment to handle emergency poisoning cases [49, 50] and often refer cases to higher-level facilities, which can incur treatment delays. In addition, more severe cases may be more likely to attend the higher-level facilities as their first point of care. Together, these may contribute to the higher CFRs in higher-level facilities. These findings are consistent with those in the Tanzanian study which showed that higher level health level facilities had a higher CFR than lower level primary health facilities [31]. This was attributed to lack of clinical capacity amongst healthcare workers to diagnose and treat such cases at primary healthcare level. It is important that rapid referrals are done from lower-level health facilities to higher level health facilities. In areas in which organophosphate poisonings comprise a high proportion of patient visits, it may be worthwhile to stock antidotes and train staff to manage such cases until they can reach higher-level facilities. Higher-level health facilities should additionally be equipped to handle organophosphate poisoning emergencies.
Limitation
Our study only utilized secondary data from the DHIS2, which are limited in terms of variables available for analysis. Secondly, the study utilized information of only admitted patients, and thus outpatients and persons who did not seek care from the health facilities were excluded, resulting in an under-estimation of the incidence of organophosphate poisoning in Uganda. Community-level studies using primary data to determine the factors associated with organophosphate poisoning may be beneficial in understanding the trends of organophosphate poisoning in Uganda.