Introduction

Neglected Tropical Diseases (NTDs) are a group of disabling conditions that are among the most common infections affecting the world’s poorest people [1]. Many NTDs lead to chronic and often disfiguring conditions that result in significant disability and affect more than 1 billion people across the world [2].

Lymphatic filariasis (LF) is a mosquito-borne disease caused by filarial parasitic worms like Wuchereria bancrofti, Brugia malayi and Brugia timori [3]. Global estimates suggest that 120 million are affected in 80 countries throughout the tropics and subtropics with people at risk exceeding 1.3 billion [4, 5]. LF often manifests as enlargement of the entire leg or arm, the genitals (scrotal hydrocele in men), vulva and breasts leading to significant physical disfigurement [3]. Significant social stigma is associated with this stage of the disease [6], and the psychosocial problems linked with the condition are believed to be more severe than the physical ones [7].

In the 2010 Global Burden of Disease study, the Disability Adjusted Life Years (DALYs) associated with depressive illness in lymphatic filariasis was found to be twice that of the physical consequences of the disease (5.09 million global DALYs vs 2.78 million respectively) [8]. Despite this report, very few studies have been carried out to explore the association between depressive illness and lymphatic filariasis.

This study, therefore, aimed to determine the prevalence and severity of depression and the social and clinical factors associated with depression in individuals with lymphatic filariasis in Plateau State, North Central Nigeria.

Methods

The study was carried out in five catchment areas in Plateau State where people living with LF periodically meet to receive physical care and support. These centers are run by the Carter Center, a US-based international Non-Governmental Organization (NGO). They include Tudunwada (Jos North Local Government Area (LGA)), Nyes (Mangu LGA), Ampier (Kanke LGA), Dadur (Langtang LGA) and Gwamlar (Kanam LGA). These sites include both rural and urban communities and were chosen as they have a high prevalence of LF.

The study population included all individuals accessing care at these five centers in Plateau State with obvious physical manifestation of the condition and who were available on site on the day of the visit of the research team. Advance notice was sent to all the Centers about a month before the visit, inviting potential participants to attend. There is no reason to believe that the attendees on these clinic days vary systematically from those attending on other days, though they are characterised by their access to clinical and rehabilitative care, which is not universal in Nigeria.

A cross-sectional 2-stage descriptive convenience study design was adopted. It involved the recruitment of all available and consenting individuals with physical manifestations of LF. Data was collected using a semi-structured socio-demographic questionnaire designed by the research team and a 9-item Patient Health Questionnaire (PHQ-9) for the first stage. Those who screened positive (with a score of 5 and above) were further interviewed using the Depression module of the Composite International Diagnostic Interview (CIDI) to make definitive diagnosis and rate the severity of the depression. Rosenberg Self-esteem scale was used to assess self-esteem in the study population.

On each day of the visit to a particular center, all participants were briefed on the purpose of the study. Each participant was then approached, given a more detailed explanation, consent obtained and the interview conducted in private. Six researchers (two consultant psychiatrists, a clinical psychologist, a social worker and two resident doctors in psychiatry) administered the socio-demographic, Rosenberg self-esteem and the PHQ-9 questionnaires to the participants and scored the PHQ-9. Those who scored 5 and above were sent to 2 consultant psychiatrists trained in the use of CIDI for the second stage. The participants were then formally diagnosed and rated for severity of the depression.

All those who screened positive for depression using the CIDI were given advice and information (psycho-education), and those who had moderate and severe depression were referred to a nearby comprehensive health facility for further treatment. They have subsequently been followed up in an on-going psychosocial service being developed at the Centers.

Results

A total of ninety-eight participants, who met the inclusion criteria and gave consent for the study, were interviewed. Ninety-four (95.9%) had full documentation and were analysed. The majority, 58 respondents (61.7%), were female. Other socio-demographic details are provided in Table 1.

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Table 1. Socio-demographic characteristics of study participants.

https://doi.org/10.1371/journal.pntd.0005567.t001

The median duration of illness was 17 years (IQR 7.0–30.0 years). Twenty-three (24.5%) had the illness for more than 30 years. 21 respondents (22.3%) rated their level of functioning as poor. Other details of functioning, as well as perceived adequacy of support are presented in Table 2.

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Table 2. History of mental illness, economic status, functioning and adequacy of support.

https://doi.org/10.1371/journal.pntd.0005567.t002

Nineteen respondents (20%) met criteria for depression, using CIDI, with the severity of the depression being Mild [8 (42.1%)], Moderate [6 (31.6%)] and Severe [5 (26.3%)]. See Fig 1.

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Fig 1. Severity of depression among respondents.

https://doi.org/10.1371/journal.pntd.0005567.g001

Fourteen of the depressed respondents (73.7%) were female. Furthermore, 69 respondents (73.4%) reported low self-esteem. See Table 3.

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Table 3. Prevalence of depression and low self-esteem.

https://doi.org/10.1371/journal.pntd.0005567.t003

Logistic regression analysis revealed that history of mental illness (OR 40.83, p = 0.008); duration of the illness between 11–20 years (OR 5.02, p = 0.079), being unemployed (OR 12.71, p = 0.003) and Self Esteem (OR 0.09, p = 0.004) were predictive of depression in the cohort. High self-esteem was negatively correlated to depression. See Table 4 below.

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Table 4. Predictors of depression.

https://doi.org/10.1371/journal.pntd.0005567.t004

Discussion

Lymphatic filariasis cuts across all age-groups affecting both the elderly and the young with a slight preponderance in the mid to older age group. The over-representation of women (61.7%) in the study population is in keeping with the population of people receiving care at the Centers. The percentage of the participants who were separated/ divorced was higher than the expected in the general population (35.1% as against 6.8% in the general population) [9] and is in keeping with typical findings among this study population in relevant literature. They are less likely to be married, often described as the “last choice” in qualitative studies, and when the disease manifest itself during their married life, it may lead to divorce (7, 8). Nearly half of the study population (46.8%) had no formal education but this is not a sharp departure from typical rates in the rural population of the country [9]. The participants were largely self-employed as farmers and traders, which reflects the usual occupation of the people in the study areas. The average monthly income of more than three-quarter of the study population was less than N10, 000 (<$50 monthly) and this was described by more than 80 percent of the participants as inadequate. This is in keeping with the fact that NTDs principally impact the world’s poorest populations, as well as being a driver to poverty by itself [1]. The median duration of illness was 17 years (IQR 7.0–30.0 years), with about a quarter being over 30 years, illustrating relatively early onset and the chronic nature of the condition.

The percentage of those found to be depressed among the people with lymphatic filariasis (20%) is higher than the reported prevalence of depression among adults in Nigeria (3.1–5.2%) [10, 11, 12] and in primary care patients [13]. It is, however, similar to reported prevalence of depression in chronic medical conditions [14], who have been found to have two- to three- fold higher rates of major depression when compared with age- and gender- matched primary care patients [15, 16].

More women were found to be depressed among the study population, with a female to male ratio of almost 3:1. This large difference cannot be explained by the higher representation of women (F:M ratio of 1.6:1) in the study sample, and is also higher than the reported two-fold greater prevalence of Major Depressive Disorder in women than men in the general population [17]. This may be associated with greater social exclusion or stigmatisation experienced by women than men.

History of mental illness is an important and recognised risk factor, as such individuals are at greater risk of a relapse or development of another mental illness. Individuals with previous history of mental illness are almost 41 times more likely to be depressed than those without a previous history in our study.

Participants with low self-esteem, as measured by the Rosenberg self-esteem questionnaire in this study, were more likely to have depression when compared to those with high self-esteem. This could be attributable to the fact that people with depression are more likely to have low self-esteem. Our study, and many others in the region [18] and elsewhere have found that low self-esteem is often seen in people with NTDs possibly as a consequence of self-stigma, discrimination and limitations in functioning. This would suggest that high self-esteem is protective against the development of depression among this group. This is in keeping with recognised mechanisms linking stigma and depression, and may point towards potential therapeutic or health promotion interventions [19]. The link between social stigma and mental illness, including depression, are reported to be cyclical and reinforcing [19]. Self-stigma, a self-imposed restriction of expectations is common and may negatively affect expectations and motivation to engage socially [20]. In fact, people affected by LF will experience both the stigma associated with their physical condition and of their comorbid mental health problems.

Duration of the illness may be associated with higher prevalence of depression for a number of reasons. This may include the chronicity of exposure to risk factors inherent in the condition (disfigurement, pain, disability) which would be further compounded by the severity of the illness (likely to be greater in longer-term illness). It is also possible that there will be a greater extent of social drift over time. In keeping with this, unemployment was also found to be associated with greater prevalence of depression. This is the pattern found with many psychiatric disorders, where there is a vicious cycle of mental illness provoking poverty (through mechanisms summarised as social drift) and poverty being a risk factor for mental illness (social causation, or poverty as a social determinant) [21].

Conclusion

Beyond the physical burden of living with lymphatic filariasis, people with the condition also have significant psychiatric complications (particularly depression). Appropriate treatment for depression has been found to improve outcomes in other chronic conditions [22]. Therefore, given the high prevalence of depression, providing access to mental health screening and interventions should be integral to NTD programmes. Thus, in addition to attending to physical needs, emotional needs should also be routinely assessed and catered for.

It is recommended that staff should be sensitised to the high risk of depression and be trained to recognize basic signs and symptoms of depression. Simple screening instruments for depression, such as the PHQ-9 can also be utilized in routine clinics, and those found to be depressed can be treated or referred appropriately. Health promotion strategies geared towards assessing and addressing factors associated with depression (for example self-esteem) should be incorporated in routine community engagement, including health talks in the clinic. These are simple steps that can easily be incorporated into specific NTD services, and general health care for endemic populations, providing the possibility of improving the quality of life of affected persons, and reducing the negative impact of depression on an already marginalised population.

Supporting information

Acknowledgments

The authors acknowledge the support of the Health and Development Support (HANDS) Programme and The Carter Center, who provided access to their programmes, and the Jos University Teaching Hospital, who provided the local research expertise. We also acknowledge the contribution of Dr Toyin Aderemi, of the CBM Nigeria Country Office, towards the success of this project.