Introduction
On October 6, 2018, a collision between a trailer truck and a tanker truck carrying 25 m³ of fuel at the Mbuba marketplace resulted in an explosion that killed 75 people and severely burned 67 others [1].
Road traffic accidents and related disasters may cause significant psychopathology, including depression, anxiety disorders, specific phobia, acute stress disorder, and post-traumatic stress disorder [2,3]. Motor vehicle accidents are among the leading causes of PTSD in the general population [4,5].
PTSD is characterized by the occurrence of characteristic symptoms following exposure to a traumatic event. The disorder presents with four symptom clusters: re-experiencing, avoidance, negative alterations in cognition and mood, and marked hyperarousal (hypervigilance, exaggerated startle response). Dissociative manifestations (depersonalization and derealization) may also be present. In road traffic accidents (RTAs), intrusions such as nightmares mainly consist of memories of the accident (braking sounds, impact, emergency sirens, screams, the sight or smell of blood). Recalling the event elicits substantial emotional distress [6,7].
Population-based studies report a lifetime risk of post-traumatic stress disorder of approximately 10% following trauma exposure. This risk increases to 50% or higher among survivors of sexual assault, war, military detention, genocide, and political imprisonment [6].
Post-traumatic stress disorder is associated with psychiatric comorbidities, poor quality of life, and increased risk for psychosomatic conditions including hypertension, diabetes, peptic ulcer disease, hormonal dysregulation, and chronic pain [8].
Post-traumatic stress disorder also shows intergenerational effects, with trauma-related psychopathology observable in descendants of affected individuals [9-11].
PTSD risk is influenced by sociodemographic factors (female sex, low socioeconomic status, low educational attainment, unemployment), medical history, and the severity and nature of the traumatic event [7,12].
Tanker truck explosions regularly make headlines. In 2019, at least 75 people died and 70 were injured while siphoning fuel from a tanker near Morogoro, Tanzania [13]. More than 140 people died under similar circumstances in northern Nigeria [14]. At least 230 people died and around a hundred were injured in a tanker truck explosion near the village of Sange, about a hundred kilometers from Bukavu, the capital of South Kivu province [15].
To our knowledge, no study has assessed the prevalence of post-traumatic stress disorder or its associated factors among survivors or witnesses of tanker truck explosions. Research in sub-Saharan Africa has instead focused primarily on post-traumatic stress disorder in conflict settings. In a cross-sectional study aiming to determine the frequency of PTSD in outpatient consultations at the Bangui General Hospital in a context of armed conflict, Mpembi et al. reported a frequency of 50.48%, including 33.33% for PTSD and 17.14% for acute stress disorder [16]. Bayer et al. found a PTSD rate of 34.9% among former child soldiers in Uganda and the Democratic Republic of Congo [17].
Currently, the prevalence of post-traumatic stress disorder and its risk factors among witnesses of road traffic accidents in the Democratic Republic of Congo remain undocumented. This study was therefore conducted among adults who directly witnessed the October 6, 2018 tanker truck explosion in Mbuba, aiming to estimate the prevalence of post-traumatic stress disorder and identify its associated factors.
Methods
Study setting
This study was conducted in Mbuba, an area within the Boko grouping, Ngufu sector, Madimba territory, Lukaya district, Kongo Central province, in the DRC. Residents of Boko and surrounding villages established the Mbuba market in the 1960s. It experienced considerable growth in the 2000s, to the point of giving its name to the area. The population of Mbuba is approximately 1,500 inhabitants, with an area of 15,000 km² [18].
Study type and period
This was a descriptive cross-sectional study conducted from February 2 to March 30, 2019.
Study population
This study included adults aged ≥ 18 years who were direct witnesses to the explosion that followed the collision between a trailer truck and a tanker truck at Mbuba on October 6, 2018. Participants unable to answer the questions and/or presenting with cognitive impairment affecting comprehension of the questions were excluded from the study.
Sampling technique and study procedure
Trained investigators visited Mbuba on market days (Saturdays) and administered a French-language questionnaire to participants. Data collection was made possible through a research clearance letter issued by the administrative authorities and the authorities of Kongo University. Participants were included in the study by convenience sampling. Over the two-month study period, nine investigators met with participants, each of whom was asked to present a form of identification; identity details were used to eliminate duplicate entries. A total of 900 people were interviewed.
Data collection tools
Sociodemographic characteristics (age, sex, marital status, socioeconomic status, educational level), medical history, and substance use were collected using an ad hoc questionnaire.
PTSD frequency was calculated using the Post-Traumatic Stress Disorder Checklist for DSM-5 (PCL-5). This is a 20-item questionnaire used to screen for symptoms of post-traumatic stress disorder (PTSD). The total score ranges from 0 to 80; current literature considers a score of 33 or higher to be positive, indicating the possible presence of post-traumatic stress disorder. The PCL-5 has been validated in French and shows good psychometric properties: stability (test-retest reliability between 0.79-0.94), good diagnostic accuracy (for a score ≥ 33), and sensitivity to change [19].
Dependent variable
PTSD frequency:
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Score ≥ 33: presence of PTSD
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Score < 33: absence of PTSD
Independent variables
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Age: < 35 years / ≥ 35 years
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Sex: Male / Female
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Marital status: Living alone (single, widowed, divorced) / Living with a partner (common-law union)
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Socioeconomic status: Low socioeconomic status (monthly income < US$30); Higher socioeconomic status (monthly income ≥ US$30). This threshold was set based on World Bank data [20].
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Educational level: Low (primary school certificate at most); High (at least a secondary school diploma).
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Medical history: physical assault, fractures and head trauma, chronic diseases (hypertension, diabetes mellitus), history of hospitalization, and disfiguring scars.
Statistical analysis
Data were analyzed using Epi Info (version 7.2.6.0). Categorical variables are presented as frequencies and percentages. Associations between PTSD and sociodemographic factors were tested using the chi-square test, or Fisher’s exact test when expected cell counts were < 5. Statistical significance was set at p < 0.05.
Ethical considerations
Informed consent was obtained from all participants, who consented after receiving clear, complete, and appropriate information about the survey. Anonymity and confidentiality of data were ensured at every stage of the study, from data collection to the presentation of results. Ethical approval was granted by the Ethics Committee of the School of Public Health of the University of Kinshasa, under reference ESP/CE/Q78/2025.
Results
Sociodemographic characteristics
Sociodemographic characteristics of the 900 participants are summarized in Table 1.
| Sociodemographic characteristics | n = 900 | % |
| Age | ||
| < 35 years | 491 | 54.6 |
| ≥ 35 years | 409 | 45.4 |
| Sex | ||
| Male | 489 | 54.3 |
| Female | 411 | 45.7 |
| Marital status | ||
| Married | 582 | 65 |
| Single | 318 | 35 |
| Educational level | ||
| High | 567 | 63 |
| Low | 333 | 37 |
| Monthly income | ||
| Higher socioeconomic status | 415 | 46.1 |
| Low socioeconomic status | 485 | 53.9 |
Participants’ ages ranged from 18 to 80 years (mean = 35.4, SD = 12.5). The sample was predominantly male (54.3%) and under 35 years of age (54.6%). Subjects living with a partner and those with a high educational level each represented nearly two-thirds of the sample. More than half of the sample (53.9%) lived on less than $30 per month.
Medical history
Physical assault, fractures, and head trauma were reported by 7.2%, 5.1%, and 2.5% of participants, respectively. Chronic diseases and disfiguring scars were reported by 19.3% and 2.8% of participants, respectively.
| History | n = 900 | % |
| Physical assault | 65 | 7.2 |
| History of fracture | 46 | 5.1 |
| Head trauma | 23 | 2.5 |
| Chronic diseases | 174 | 19.3 |
| Disfiguring scars | 25 | 2.8 |
Substance use
Alcohol, tobacco, and cannabis use was reported by 358 (39.8%), 172 (19.1%), and 41 (4.6%) participants, respectively.
| Substance use | n = 900 | % |
| Alcohol | 358 | 39.8 |
| Tobacco | 172 | 19.1 |
| Cannabis | 41 | 4.6 |
Prevalence of post-traumatic stress disorder
The prevalence of probable PTSD (PCL-5 score ≥ 33) in this sample was 50.1%.
| Post-traumatic stress disorder (PCL-5) | n = 900 | % |
| Score ≥ 33: presence of PTSD | 451 | 50.1 |
| Score < 33: absence of PTSD | 449 | 49.9 |
Sociodemographic factors and PTSD
Age ≥ 35 years (p = .06), female sex (p = .34), low educational level (p = .06), and low socioeconomic status (p = .08) showed no significant association with PTSD. Living with a partner was significantly associated with a higher likelihood of PTSD (p = .002).
| Factors | PTSD (PCL-5) (%) | P |
| Age | ||
| < 35 years | 47.40 | 0.06 |
| ≥ 35 years | 53.81 | |
| Sex | ||
| Female | 51.82 | 0.34 |
| Male | 48.67 | |
| Marital status | ||
| Single | 43.08 | 0.002 |
| In a relationship | 53.95 | |
| Educational level | ||
| Low | 54.05 | 0.06 |
| High | 47.80 | |
| Income | ||
| < 30 USD/month | 52.78 | 0.08 |
| ≥ 30 USD/month | 46.99 |
Psychoactive substance use and PTSD
Alcohol (p < .001), tobacco (p < .001), and cannabis use (p = .007) were all significantly associated with PTSD.
| Substances | PTSD (PCL-5) | n | % | P |
| Alcohol | Yes | 209 | 58.38 | <0.001 |
| No | 242 | 44.65 | ||
| Tobacco | Yes | 111 | 64.53 | < 0.001 |
| No | 340 | 46.70 | ||
| Cannabis | Yes | 29 | 70.73 | 0.007 |
| No | 422 | 49.13 |
Discussion
This study aimed to assess the frequency of, and identify factors associated with, the occurrence of PTSD among nine hundred residents of Mbuba and its surroundings. Half of the subjects surveyed had PTSD symptoms. Living with a partner, and alcohol and tobacco consumption, were statistically significantly associated with the occurrence of PTSD. By contrast, age ≥ 35 years, low educational level, and low socioeconomic level were non-significantly associated with the occurrence of PTSD.
Frequency of PTSD
The prevalence of PTSD observed in this study was 50.11%. This frequency is relatively high compared with results generally reported in the literature. In Ethiopia, a study of 492 adult road traffic accident survivors followed at five public hospitals 30 days after the traumatic event found an observed PTSD frequency of 22.8%. That study identified female sex, low social support, depression, and a post-accident care duration of 1-3 months as factors associated with PTSD among RTA survivors [21].
Another study conducted in southeastern Nigeria on road traffic accidents and post-traumatic stress in an orthopedic setting also revealed the negative impact of RTAs on subjects’ health. The age range of the road accident victims in that study consisted of young adults, with a mean age of 31.61 ± 9.18 years; three-quarters were male. The frequency of PTSD was 26.7% among injured RTA victims. Accidents had occurred at the earliest one month and at the latest twelve months before consultation [22]. Subjects were interviewed using the English-language version of the Mini International Neuropsychiatric Interview (M.I.N.I) to establish a PTSD diagnosis.
The negative impact on mental health among RTA survivors varies considerably depending on the country of study, sample size, timing of PTSD assessment, the tool used to assess PTSD, the severity of the event, loss of occupational activity due to the accident, and disruption of commercial and professional activities, accompanied by probable financial difficulties among subjects [22,23].
The high frequency observed in this study can be explained by several factors: the intense emotional burden generated by the traumatic event, the nature of the event and of the injuries sustained, the absence of psychotherapeutic and psychiatric care after the event to immediately reduce the intensity of emotional distress, the lack of social support, and the presence of stigmata from the fire at the Mbuba marketplace several months after the accident. From a cultural standpoint, Africa is the most Christian continent in the world, and this growth has been even more pronounced in the Democratic Republic of Congo, reaching 95%. Fire is often associated with the Holy Spirit among Christians; on its negative side, fire burns, destroys, and ravages, evoking the fire of the passions (hatred, anger, discord, revenge) or the fire of hell, which burns without being consumed, causing eternal suffering. In our population, the negative religious conception of death by fire may have contributed to this high frequency of PTSD [24,25].
Conversely, the frequency of PTSD in this study is lower than that reported in a Canadian study of a train derailment in downtown Lac-Mégantic, Quebec. On July 6, 2013, in the middle of the night, a 72-car train carrying crude oil derailed in downtown Lac-Mégantic, causing a series of explosions, a fire covering 5.7 hectares of the town, the death of 47 people, and the destruction of numerous buildings, including 5 private residences, 66 apartments, and 44 businesses. This disaster forced the evacuation of more than 2,000 people, 169 of whom were never able to return to their homes, and released more than five million tons of crude oil into the environment. Three years after the event, a survey of a sample of 800 adults aged 18 years and older, including 282 men, found a PTSD frequency of 72.1% [23]. That study used the 1979 Horowitz, Wilner, and Alvarez Impact of Event Scale to assess PTSD three years after the traumatic event. Exposure to various secondary stressors, such as the continued operation of rail traffic downtown, the destruction of homes in the affected area, and the reduction of psychosocial services, was likely responsible for the delay in the recovery process among the men, and the population as a whole, affected by the tragedy [23].
Following a fire, the frequency of post-traumatic stress symptomatology tends to increase over time. Many factors can heighten subjects’ vulnerability, including the intensity of exposure, proximity to the event site, duration of exposure to fire-related odors, having heard the sound of the fire, low socioeconomic status, lack of social support, personality traits, resilience, and history of psychological disorders. These disorders can persist for several years after a fire [23].
Sociodemographic factors and PTSD
Age ≥ 35 years, low educational level, and low socioeconomic status showed no significant association with PTSD.
Living with a partner was statistically significantly associated with the occurrence of PTSD (p ≤ 0.05).
Living with a partner is generally associated with certain health benefits [26]. One possible explanation is that participants with family responsibilities experienced heightened survivor guilt or anticipatory distress regarding the potential impact of their own death on dependents.
Marital stress has already been associated with a higher incidence of psychiatric disorders; this type of stress can compromise the process of emotional response, and prolonged tension within a couple can reduce spouses’ capacity to appreciate positive experiences [26]. With the various professional and family responsibilities, together with shared plans as a couple, many relationships become overwhelmed by marital and professional stress [27]. These various responsibilities constitute an acute or chronic stress factor that can promote the occurrence of mental disorders such as PTSD [28].
Substance use and PTSD
Alcohol (p < 0.001), tobacco (p <0 .001), and cannabis use (p = 0.007) were significantly associated with PTSD.
PTSD and psychoactive substance use are two comorbidities linked in a bidirectional biopsychosocial relationship. Biologically, acute or chronic stress leads to elevated levels of hormones such as cortisol and other circulating molecules.
Corticotropin-releasing factor (CRF) and cortisol are strongly implicated in the occurrence of addiction and PTSD (28,29). Psychosocially, the affective disturbances associated with PTSD induce risk behaviors, notably substance use, as a means of reducing emotional disturbance. Substance use may be a coping strategy used by subjects with PTSD seeking to reduce their symptoms [30,31]. Early use of psychoactive substances impairs the learning of coping strategies for dealing with stressful situations. Five out of every ten patients treated for substance use present with PTSD [31].
Conclusion
This study found that half of Mbuba’s residents had PTSD. RTAs involving fire are associated with a higher frequency of PTSD. The lack of care for subjects in the days and weeks following the accident likely contributed to the high frequency observed in this study. Given that individuals affected by PTSD present a vulnerability that can also be found in their descendants, major mental health problems can be anticipated in the region in the coming years.
The results of this study highlight the need to ensure appropriate biopsychosocial care in the face of any traumatic event, particularly RTAs, which are so frequent on National Road No. 1 in Kongo Central province. Biopsychosocial care for any traumatic event should be ensured by qualified personnel.
Declarations
Ethical Approval and Informed Consent
Ethical approval was granted by the Ethics Committee of the School of Public Health, University of Kinshasa (Ref. ESP/CE/Q78/2025). Informed consent was obtained from all participants, and anonymity and confidentiality were maintained throughout the study.
Conflicts of Interest
The authors declare no conflict of interest.
Funding Statement
None
Data Availability Statement
All data supporting the findings of this study are available upon request from the corresponding author.
Authors’ contributions
Hergy Bazungula Mumpasi: literature review, database management, statistical analysis, writing.
Justin Muilu Pila: review and proofreading.
Jacques Kinkumpa Benangindu: review and proofreading.
Victoria Kubuta Massamba: supervision, review and proofreading.
Thierry Matonda-Ma-Nzuzi: supervision, review and proofreading.
Odon Nzuzi Mabiala: data collection, encoding, and statistical analysis.
Landry Daniel Nsekoko Bola: data collection, encoding, and statistical analysis.
Christiane Mboma Diafuana: data collection, encoding, and statistical analysis.
Magloire Nkosi Mpembi: conception, literature review, statistical analysis, supervision.
Acknowledgments
The authors thank the study participants for their cooperation and their adherence to the survey by providing the necessary information.
The authors also thank the scientific and administrative authorities for facilitating access to certain documents that made this work possible.