The study describes the trend of malaria admissions and the outcome of patients with severe malaria in EFSTH after the start of COVID-19 in The Gambia. Most of the malaria patients admitted to EFSTH during the study period were adults. The admitted adults were at least twice more as the admitted paediatric patients. This result confirms the increasing number of malaria in youths and older adults in The Gambia and is consistent with the age shift in incidence of infection towards older children which happens with endemic infectious diseases in low transmission settings [1, 15]. It is however unlike a study done in Kenya, which did not find a significant burden of severe malaria in the adults [16].
Most of the adult patients were within the youth age group but the youth-to-older adult ratio decreased overtime suggesting that more older adults also got infected after a while. This could be explained by the waning of the malarial immunity in adults following decreased exposure to parasites [15, 17,18,19]. There were also more male malaria patients than female and the male to female ratio also decreased over the three transmission seasons. In general, females show stronger humoral and cellular immune responses to infection or antigenic stimulation than males [20]. Gender-based occupational or behavioural factors have also been implicated in the gender differences seen in low transmission settings [15]. The COVID 19 pandemic also resulted in significant job loss across the globe and males were more affected, especially those who worked in non-agricultural industries [21, 22]. This may have resulted in lesser number of males engaging in occupations that predisposes them to malaria infections and thus contributing in the reduction of the male to female ratio over time. Other studies have also shown a high burden of malaria in adult females especially after the typical childbearing age (i.e. above 39 years of age) due to the positive health-seeking behaviours of females in these health facilities [19]. A study done during the COVID 19 pandemic also suggested changes in health behaviour with females less likely to be engaged in positive health behaviours compared to males [23]. This behavioural factor may have also resulted in the increase number of females having malaria and thus decreasing the male to female ratio over time. With less bias in the proportions in the most recent transmission season, an increasing number of older adults and females have likely either lost their immunity to malaria overtime or have not developed this due to low levels of exposure following malaria decline in The Gambia. This presents a risk to the vulnerable population (children and pregnant women), as infected adults could serve as a reservoir which spread and sustain transmission against intervention efforts. Beyond the declining transmission and incidence, other factors affecting the age shift and sex distribution of incident cases of referral malaria in The Gambia remains unclear and needs further investigation.
The total number of admitted malaria cases increased by 84% from 2021 to 2022 and admission peaked in November in both years. The Gambia suffered four intensive COVID-19 waves and 3 of those were in 2021 (2nd, 3rd and beginning of the 4th waves) (Fig. 4). Out of the total number of confirmed COVID-19 cases diagnosed between 2020 and 2022, 3791 cases were diagnosed in 2020, 6681 in 2021 and 1846 cases in 2022 [24]. This showed an increase number of COVID-19 cases in 2021 as compared to 2022. This increase number of COVID-19 cases in 2021 most likely led to: (1) reduced access to healthcare services due to the pandemic control measures (such as the declaration of a state of emergency (SOE) [25], (2) a high level of fear and worry related to COVID-19 in Gambian adults [4] in the early phase of the pandemic resulting in delay in presenting to health facilities or not even visiting health facilities, (3) negative impact on the malaria preventive measures such as distribution of insecticide-treated nets (ITNs), indoor residual spraying, chemoprevention for pregnant women and young children [8, 9, 26], and (4) an undesirable effect such as the stock out of malaria test kits, reagents and medications meant for the testing and treatment of malaria [25].
There was also a spike in the number of admitted malaria cases in August 2022, which corresponds to the beginning of 2022 season. In late July and early August 2022, The Gambia suffered unprecedented torrential rainfall that resulted in widespread flooding in many communities [Greater Banjul area (Tobacco road), Ebo Town, Kotu-Manjai, and Nemakunku]. This flood was the most severe disaster the country has recorded in decades that affected more than fifty thousand people in the suburbs of urban settlements [27]. As already known, climate change also has an effect on the incidence of vector- borne diseases, such as malaria [28,29,30]. The increase number of admitted adult malaria patients in the early months of the 2022 malaria season most likely may have been triggered by these floods exposing this already vulnerable population to malaria infection.
The study also showed a higher number of admitted malaria cases during the peak of the malaria season in September to December 2022 as compared to September to December 2021.This jump in cases in the recent transmission season could be an indication of post- COVID-19 resurgence of malaria. It could have also been due to a decrease number of testing or diagnosis of malaria in the September to December 2021 season as majority of COVID 19 cases in The Gambia were recorded in 2021 (Fig. 4). This could have caused a disruption in testing or diagnosis of malaria resulting in decrease number of admissions in the September to December 2021 season. There is, therefore, need for increased monitoring and surveillance plus targeted preventive interventions to curb further rise in admitted malaria cases as previously suggested [4]. Malaria interventions predominantly target rural endemic areas, meanwhile, urban malaria is becoming more important. The persistent and continuous rise in malaria cases in the adult urban and peri-urban population presents a risk of spread to younger children and pregnant women, who account for most of the global mortality in higher transmission settings.
There was also an increase in both severe and uncomplicated malaria during this same period (2021 to 2022). Severe malaria cases were predominant in the first and fourth quarters of the year and uncomplicated malaria in the third quarter of the year. As patients with severe malaria are more likely to die, knowing the time the severe cases peak will help Government through the Ministry of Health and National Malaria Control Programme to deploy more preventive measures and intensify health promotion activities during this period. It could also inform decision on committing more resources (e.g. personnel, diagnostics and medications) to the health facilities during this period to prevent mortality.
The total mortality was 31 (9.7%) and mortality in 2021 and 2022 were similar. Mortality was significantly higher in October 2020 to February 2021 compared to October 2021 to February 2022 and October to February 2023. This is consistent with our previous finding as October 2020 to 2021 coincided with the end of the first wave of the COVID-19 pandemic in The Gambia [4]. Impaired consciousness using Glasgow coma score (GCS) at the time of presentation compared to those without impaired consciousness was found to be associated with death. This was also similar to the previous study [4] and has also been confirmed in several other studies in malaria-endemic and non-endemic areas [16, 31, 32]. In contrast to the previous study [4], this study also found significant relationship of death with malaria patients with AKI which is similar to the findings of other study done in African adults [31]. This adverse impact of AKI could have been due to several factors: (1) Delayed referral of patients especially those in the rural areas, (2) Limited number of critical care beds, monitoring equipment, and the capacity of personnel to provide basic critical care services such as blood transfusion at the different hospitals [33], (3) Limited access to dialysis as there is only one haemodialysis unit in the country which caters for all patients with dialysis requiring kidney failure.
One of the limitations of this study is the fact that it is a retrospective single-centre study, and the results may not be generalizable to other settings. Secondly, due to the limited access to laboratory investigations, severe malaria features such as hyperparasitaemia and acidosis could not be assessed. Notwithstanding, the study provides an understanding of temporal trends of malaria admission and outcomes in a tertiary hospital after the start of COVID-19 in The Gambia.
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