Pattern of acute poisoning at two urban referral hospitals in Lusaka, Zambia
In the present study, it was observed that the majority of poisoning cases were in children involving accidental circumstances. Literature shows that although accidental poisoning can occur at any age, it is most common in children with peak age around two years [10, 14–16]. Hand to mouth behaviour of inquisitive children as they explore the world around them, coupled with the lack of knowledge of consequences puts the children at a higher risk of poisoning [2, 17]. Overall, non sex differentiation was observed in the distribution of poisoning cases reviewed in this study. Age and sex distribution of poisoning burden vary in different geographic regions and time periods due to the interaction and influence of socioeconomic, cultural and behavioural factors in the general population [17–19].
The mortality rate of 2.6 per 100 cases noted in this study was similar to findings in a study conducted in South Africa [3]. A male predominance in deaths was observed in the poisoning cases reviewed in this study. This pattern has been observed by others and has been attributed to the male tendency to choose more violent and successful means of self-harm than women [16, 19]. Furthermore, high case fatality rates were associated with pesticide poisoning. This observation can be attributed to the high toxicity of these agents. However, other toxicological factors – such as potency of toxic agent and amount exposed to – also need to be put into consideration with regard to survival of the victims. While mortality is usually high in patients of deliberate self-harm, a study in rural Sri Lanka found that the choice of poison was based on availability and not toxicity of the poison [20].
The finding that the most prevalent chemical agents involved in poisoning were pesticides and pharmaceuticals was not surprising because these tend to be the most predominant chemicals in poor resource settings. Existing literature shows that toxic agents associated with morbidity and mortality are influenced by various factors such as location, time periods, availability and use of chemicals or poisoning agents, as well as changes in lifestyles, beliefs and traditions of people [21, 22]. To this effect, we observed similarities and differences in findings from our study and those found by others. For instance, a Zimbabwean study revealed that pesticides and pharmaceuticals were the most common toxic agents responsible for hospital admissions [16]. In Francistown and Gaborone, Botswana, household chemicals and pharmaceuticals were the predominant cause of acute poisoning [3]. In Kampala, Uganda, agrochemicals, household chemicals and carbon monoxide were more prevalent among the cases [23]. A study conducted in Hong Kong found sleeping pills and analgesics to be the most common poisons [9]. In Khuzestan region, South Western Iran, envenomation by scorpions, spiders and snakes was the major cause of poisoning [24].
Though only a few cases with narcotic poisoning were recorded in the present study, this observation is of particular importance since Zambia has in recent years become a consumer of hard drugs as evidenced by the increasing number of drug-dependent persons attended to by the Drug Enforcement Commission [25]. This increase in the rate of drug abuse observed poses a threat to public health in the near future. In addition, our study showed that children recorded more cases of poisoning with kerosene. This finding is in support of evidence in the literature that kerosene and paraffin oils are often kept in unsafe non-child-proof containers, resulting in accidental ingestion of the chemicals by children [17].
The number of snake envenomation cases recorded in this study was in accordance with those recorded in studies within countries such as Zimbabwe, Uganda and South Africa where more than 10 % were affected [16, 23]. As noted by the WHO, snake bites are an important public health issue in rural areas of sub-Saharan African countries – like Zambia – where the burden of snakebites is also high [26].
Background factors such as residence and socioeconomic status have been associated with acute poisoning elsewhere [27, 28]. Residential areas in urban Lusaka are classified as high, medium and low-cost housing areas based on the infrastructure and social services available. Studies and surveys have shown distinct differences in socioeconomic characteristics among these classes such as level of education, income and employment status [29]. A gradient in number of cases was observed with regard to area of residence. Most of the cases were from low cost, densely populated residential areas suggesting an influence of socioeconomic status and living conditions on acute poisoning.