Men of refugee and migrant backgrounds in Australia: a scoping review of sexual and reproductive health research

Keywords: Australasia, health promotion, health services, men, migrant and mobile populations, refugee, reproductive health, sexual health.

Involving men in sexual and reproductive health (SRH)  programs and discussions is widely recommended by global health policies to improve pregnancy, maternal and child health outcomes.^1,2 Traditionally, SRH research has disproportionally focused on women,³ and where men have been included, representation of those from refugee and migrant backgrounds is minimal.⁴ The invisibility of men from SRH research has several implications. First, designing gender sensitive SRH care would be difficult without understanding their specific needs and experiences with access to health care.⁵ Second, health promotion efforts, SRH policies and clinical practice are unlikely to be tailored to the needs of men, resulting in limited SRH literacy and poor engagement with help seeking behaviours.⁶ This results in lower uptake of preventative health behaviours including screening for sexually transmitted infections (STIs) and contraception use for pregnancy prevention, with implications for the lives of both men, women and their families.⁴ Third, there will be poor acknowledgement of the role that men may have in women’s health, which is important to engage men as supportive partners in improving contraceptive use, family planning and other SRH outcomes of women.⁷

The focus of this review is culturally and linguistically diverse men from refugee and migrant backgrounds. In Australia, people from refugee and migrant backgrounds experience inequitable health outcomes, with one major inequity being SRH.⁸ Specifically, men have unique SRH needs upon arrival, including higher rates of STIs and HIV infections.⁹ Sexual violence and trauma are also prevalent problems affecting men.¹⁰ While, they may be offered a range of SRH services during and after resettlement to meet these needs, resettlement demands are generally prioritised over SRH issues, with focus given to competing practical and social needs such as housing, employment, and childcare responsibilities.¹¹ The high burden of mental health illness among refugee men may lead to a delay in seeking care for SRH issues.¹² Given these inequities migrant and refugee men have been identified as priority groups in Australia’s National Men’s Health Policy¹³ and Men’s Health Strategy 2020–2030.¹⁴

Refugee and migrant men and women have different SRH care needs and preferred sources of care after resettlement. For example, in one study, men reported to prefer peer and online sources for SRH information,¹⁵ while women may talk with their close family members¹⁶ or would like to access groups sessions.¹⁷ In addition, men have stressed concerns about confidentiality when accessing SRH care, whereas women identified shame and embarrassment when discussing sexual health with service providers.¹⁶ These differences suggest the need to design gender sensitive SRH interventions. However, the degree of health and SRH evidence needed to design policy and health promotion interventions for men from refugee and migrant backgrounds is limited.^6,18 This review aimed to synthesise the available evidence on refugee and migrant men’s SRH needs, understandings, and experiences of accessing services after resettlement in Australia. Exploring existing SRH literature and identifying gaps in current knowledge will help to identify areas of future research and service provision to meet the needs of refugee and migrant men whose perspectives and experiences are often neglected in mainstream SRH programs and research.³

This scoping review adhered to the systematic review processes and standards described in the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA).¹⁹ The review addressed two research questions: (1) what is the published evidence of needs, understanding and experiences of refugee and migrant men in Australia in relation to their access to SRH care and factors influencing this? and (2) what are the gaps in this evidence?

We developed the search strategy based on the SRH definitions of the World Health Organization (WHO)²⁰ and a previous systematic review investigating refugee and migrant women’s SRH.²¹ The search terms covered the following SRH topics: SRH, sexual health and relationships, pregnancy, fertility, abortion, contraception, family planning, sexually transmitted infections, sexual and intimate partner violence and marriage.

The search strategy (Table 1) used the following format: Australia and (focus population terms) and (men related terms) and (SRH related key words). We included peer reviewed literature published between 2000 and 2021 and searched three major databases: Scopus, PubMed, PsycInfo. We also searched for literature in Google, Google Scholar and websites of organisations involved in SRH care research and service delivery for refugees and migrants in Australia. Reference lists of articles included in this review were screened to identify further potential articles. These steps were conducted to make sure that the review was as comprehensive as possible in identifying all relevant articles that examined the SRH of migrant and refugee men in Australia.

Table 1.  Search strategy.

Australian studies that examined the SRH needs, care access experiences and outcomes of men from refugee and migrant backgrounds were included. We use the term men to include all men, including cis-gendered men (gender identity and sex assigned at birth are the same) and trans men. We were also interested in men across differing sexualities, including gay, bisexual and heterosexual identifying men. We included studies that involved both men and women but provided results disaggregated by gender, as originally only 11 papers exclusively focused on men. Studies published in English and involved qualitative, quantitative, and mixed method designs were included. Articles were excluded if they: (1) were commentaries, reviews, letters, or books; (2) focused on women; (3) focused on Australian-born men; (4) were conducted outside of Australia; (5) did not involve empirical research methodology; and (6) SRH was not the primary focus. The PRISMA flow diagram (Fig. 1) provides reasons for exclusion.

Fig. 1.  PRISMA flow diagram.

All papers identified from the systematic search were downloaded and saved into an Endnote library for title and abstract screening using the inclusion and exclusion criteria. Two authors (ZM and AJH) independently conducted primary screening and full-text review of the articles. Results were cross-checked and differences were discussed and resolved. The fourth author (JMU) was continuously consulted over the review process when there was no agreement between ZM and AJH. A diverse range of articles involving a range of methodologies covering several areas of migrant and refugee men’s SRH were identified. Data were then extracted from the studies selected for inclusion using a template developed for this purpose. Extracted data included: first author, year, population category, research question/objective, study design, data collection approaches, SRH services referred in the study and summary results.

A framework developed by the WHO for operationalising sexual health and its relationship with reproductive health²⁰ was used to map the studies included in this review (Fig. 2). The framework was developed to explain the intertwined nature between sexual health and reproductive health and ensure both sexual health and reproductive health receive full attention in research and programming for all population groups. In addition to the eight topics from this framework, intimate marital relationship and reproductive cancers were added, as these two are integral parts of SRH. The remaining studies that broadly explored SRH were categorised under ‘other’. The analysis was informed by the socio-ecological framework that provides a multi-level lens to understanding and addressing disparities in health care access and outcomes.²² The framework is useful to understand the complexity of accessing SRH care in the context of migration to a new country.²³ Accordingly, the results from each article were coded and synthesised using the five levels of the socio-ecological framework: (1) individual such as health literacy and socio-economic factors; (2) interpersonal, which examines encounters of men with health care providers and close family members; (3) organisational, which included formal and informal rules that guide health service provision; and the larger influence of (4) the community; and (5) policies.

Fig. 2.  Framework for operationalising sexual health and its linkages to reproductive health²⁰ (blue and orange ribbons represent sexual health and reproductive health, respectively).

The systematic search resulted in a total of 1548 articles, and after 306 duplicate removals, 1242 remained for title and abstract screening. Of these, 144 were included for full-text screening. Finally, we included 38 articles that met the inclusion criteria (Fig. 1). The characteristics of the 38 included articles are summarised in Table 2. Eighteen studies adopted qualitative methods, 17 studies quantitative designs and three studies mixed method approaches. Eleven studies exclusively focused on men and 27 studies involved both men and women.

Table 2.  Characteristics of included studies.

Fig. 3 presents the number of studies grouped by SRH topics from the WHO framework. We identified 24 studies that examined the sexual health of refugee and migrant men in Australia. The majority of sexual health studies (n = 16) explored STIs, namely HIV (12), hepatitis B (3), and safe sexual practices (1). Five studies explored the topic of education and information including refugee and migrant men’s knowledge, attitude and behaviours, and their experiences of accessing, interpreting and applying sexual health information. In addition, we found three studies dealing with sexual functioning (construction of sexuality, masturbatory behaviours and help seeking preferences); three studies that examined intimate marital relationships in the context of migration to a new country, and two studies on screening behaviours for SRH cancers.

Fig. 3.  Number of studies mapped by sexual and reproductive health topics.

We also found five studies dealing with refugee and migrant men’s reproductive health: contraception counselling and provision (3), antenatal, intrapartum and postnatal care (1), and safe abortion care (1). We found no studies focusing on SRH in the context of gender-based violence prevention, support and care among refugee and migrant men in Australia. Finally, four studies that do not have a specific focus were grouped as ‘others’ (female genital mutilation (1), general SRH (2) and sexual health (1)). In the presentation of the analysis below, we describe how the identified socio-ecological factors were understood to impact SRH needs, understanding and experiences of accessing services by refugee and migrant men in Australia (Fig. 4).

Fig. 4.  Socio-ecological factors influencing the SRH of refugee and migrant men.

Studies included in the review show that men bear the majority of HIV cases among the refugee and migrant population in Australia, with the main route of transmission being among men who have sex with men (MSM).⁹ Rates of male-to-male HIV exposure and late HIV diagnosis showed an increasing trend between 2006 and 2015,^35,42 with higher rates identified among migrant and refugee men compared to Australian-born men.³⁵ In contrast, refugee and migrant men’s new HIV diagnosis rates attributed to heterosexual exposure decreased over the past decade although the rate remained higher than Australian-born men.³⁵ In addition, refugee and migrant men far outnumbered women in recent trends in heterosexually acquired HIV infection.⁴⁶

Studies included in this review identified that refugee and migrant men in Australia had varied levels of knowledge about SRH and available services. Although some studies described refugee and migrant men as having ‘reasonable’³³ and ‘widely varied’⁵² SRH knowledge, other studies identified them to ‘be inadequately informed’,⁴³ ‘held incorrect beliefs’³³ and ‘not aware of the relationship between HIV and AIDS’.⁴¹ Similarly, refugee and migrant men were identified to be unaware of the range of SRH services available to them,^29,39 including where to test for HIV,³⁴ the process of sexual health consultations,³⁹ and access to specialist SRH services.^11,39 This review has revealed contributory factors to the ‘limited’²⁹ or ‘insufficient’^39,51 SRH knowledge among refugee and migrant men. For instance, access to SRH care and information was limited in their home country for South Sudanese men and opportunities to acquire sexual health information remain limited after resettlement in Australia,⁴⁰ with the exception of school-based sexuality education for young men, which was perceived to be ‘informative’ and ‘valuable’.^11,29 Language and literacy proficiencies also made accessing online family planning information difficult for men of Afghan background.⁵⁰ SRH knowledge, however, significantly improved the longer refugee and migrant men had lived in Australia.³¹ Finally, using a peer education approach, Sievert et al.⁵³ delivered and evaluated the effectiveness of a health promotion intervention to build chronic hepatitis B (CHB) knowledge and dispel misconceptions. Their analysis revealed that refugee and migrant men demonstrated a significant change in their CHB knowledge.

We identified four quantitative studies that reported on gender differences in SRH literacy.^31-33,54 With an exception of the finding of Gray et al.³³ where men were more likely to know that condoms could prevent HIV transmission than women, the other three studies showed that men had less SRH literacy. Men reported significantly lower levels of both STI and HIV knowledge, and confidence to talk about SRH compared with women.³¹ Studies also reported lower knowledge about the sexual transmission risk of hepatitis B among Chinese- and Vietnamese-born men.⁵⁴ For Sri Lankan men living in Australia, they had more difficulty obtaining helpful contraceptive advice.³²

Across the reviewed studies, three explored attitudes in relation to fertility management.^27,50,57 Overall, refugee and migrant men were open to having fewer children following migration, associated with the belief that they experienced a reduction in authority within the family.⁵⁰ The majority of men were also open to using contraception, associating it with being ‘open-minded’ and ‘modern’ and resisting the idea that it was religiously forbidden, or something men could ‘force’ upon women. However, some men prefered not to use condoms and often relied on withdrawal to avoid pregnancies: ‘At the start, I was going with condoms, and after that, I thought ‘nah’, I went just with the withdrawal method, and that’s it … I didn’t like condoms, so I’m going with the withdrawal method and it’s working’.⁵⁰

In another study, migrant men were less enthusiastic about potential use of male hormonal contraception (MHC), with only 13.6% (95% CI: 5.8–21.4) of migrant fathers indicating they would definitely or probably consider using MHC compared with 47.5% (95% CI: 38.5–56.5) of Australian-born fathers.⁵⁷ The same study examined attitudes to two existing male contraceptive methods, condoms and vasectomy, which were significantly different between migrant and Australian-born fathers. Acceptability of condoms was highest in the south-east Asian-born men (82.4%) and lowest in men born in the Indian subcontinent (50%), with Australian-born men in-between (65.3%).⁵⁷ Migrant fathers were less likely than Australian-born men to find the idea of vasectomy acceptable, and more likely to favour a tubal ligation for their female partner over a vasectomy for themselves.⁵⁷ Finally, two papers also reported on socio-cultural beliefs in relation to abortion.^27,50 In one study with Afghan men, it was indicated that while abortion was increasingly being positioned as an acceptable option in Australia, most men remained firmly against termination of pregnancies due to religious objections. In a younger cohort of men across varying migrant and refugee backgrounds, abortion was viewed as a ‘possible’ alternative to carrying through with a pregnancy, due to cultural prohibitions around premarital sex and having children outside of wedlock.²⁷

We have also identified additional individual level factors that impact refugee and migrant men’s SRH care needs and care access experiences in Australia. A study by McMichael and Gifford¹¹ identified that the demands of resettlement takes precedence over accessing SRH care, with focus given to fulfilling practical social needs such as employment, housing and attending English language classes. In another study, refugee and migrant men living in regional areas were more likely to have had a prostate-specific antigen test than those living in urban areas.⁵⁶ Two studies examined the impact of marital status on safe sexual practices and masturbatory behaviour among men from India. While married men were less likely to masturbate than unmarried men,⁴⁹ there were no significant differences in safe sexual practices based on their relationship status.⁴⁷ Travelling to countries of origin was also identified to be a risk factor for non-adherence to HIV/AIDS care due to the inabilities of men to take treatments appropriately.⁵⁸

Studies included in this review identified language and communication barriers as main obstacles that limit refugee and migrant men’s abilities to fully understand the information provided to them by healthcare providers,^15,39,52 sometimes even with the presence of an interpreter.³⁹ Although Australia has a publicly funded translation and interpretation program, these services were not readily used by refugee and migrant men in SRH services due to concerns related privacy and confidentiality^11,39 and limited interpreter options for some ethnic groups.⁵² Consequently, language barriers made ‘it difficult to convey your pain and feeling helpless when you don’t know what is the right word’.³⁹

Shaped by previous experiences in their countries of origin, refugee and migrant men represented in some studies expressed privacy and confidentiality concerns as potential barriers to accessing SRH care in Australia.^24,26 In a study by McMichael and Gifford,¹¹ many young refugee and migrant men were reluctant to access sex related information from health care providers due to the fear of confidentiality breaches and family and community repercussions. However, ‘nonjudgmental support’ from health care providers³⁶ and having HIV test at GP surgeries provided a sense of anonymity and made refugee and migrant men feel ‘relieved’.²⁶

While the ethnicity and gender of the provider were ‘not important’⁴⁸ and ‘not a necessity’⁵⁰ for Indian and Afghan men, Iranian refugee and migrant men reported that ‘Iranian same-gender sexologists and gynecologists’ and ‘Iranian health professionals can act as enablers for Iranian migrants in providing SRH’.³⁹ Gender of the provider was also identified to be an important factor in accessing SRH care. Refugee and migrant men in a study by Sievert et al.⁵² explained that gender difference may affect their capacity to fully disclose information as ‘to be seen by a female doctor is a bit [un] comfortable for the male’.

Two qualitative studies spoke to East African migrant and refugee men’s experiences of sexual intimacy following migration.^40,45 In one study, men described Australia as a more sexually promiscuous society compared to their home countries.⁴⁵ The majority of participants positioned this negatively, associated with the erosion of sexual morals. East African men also described difficulty in negotiating socio-cultural norms, such as the collective community involvement in partner choice, with many men wanting to decide whom they wished to marry. A number of South Sudanese men spoke to a loss of power associated with migrating to Australia and women’s resistance to traditional ways of resolving relationship difficulties: ‘[She] will tell you ‘this is not Africa... here [in Australia] we have the freedom, we have our rights, everyone is equal here’. She doesn’t agree with you. So she can decide to do whatever she likes also. So here, we don’t have power very much’.⁴⁰

For some men, such loss of power led to relational conflict, the desire to return to their home countries or to select a wife from overseas, for those who were not partnered. Changes in adherence to cultural roles, in addition to financial issues and a lack of family support, was also reported among Sudanese refugee men.⁴⁰ ‘Freedom’ provided to women in Australia and changes in gender roles were also reported by men as being a major cause of conflict, marriage break up and acculturative stress: ‘The woman in Africa they don’t have freedom, here they have it. Also the wife she felt that she have rights in this country. Some of the people feel the wife now she has freedom she can do anything. She has rights now she has freedom.’ Furthermore, two studies reported the preference for participants to retain mono-ethnic relationships,^37,45 preferably heterosexual relationships.³⁷ A further study investigated experiences of migrant African men, who entered into cross-cultural relationships with Australian women.³⁸ Many men in this study reported difficulties associated with a lack of socio-cultural and economic capital, compared to their partners, leading to men feeling ‘useless’, ‘powerless’ and ‘emasculated.’

Studies included in this review identified financial barriers based on the cost of STI tests and services at organisational level.³⁴ Refugee and migrant men represented in one study explained that they ‘had to pay A$120 for 2 h consultation services and that was expensive’ and would do an HIV test ‘if it is free’.²⁶ In another study, difficulty navigating the health system including the referral system was also highlighted by refugee and migrant men as a key barrier to accessing SRH services.^34,39 Men were more likely to report not being able to find a doctor that understood their culture as a barrier compared to women.³³

SRH taboo, shaped by cultural and generational differences, emerged as an important factor shaping the way refugee and migrant men perceive and access SRH.^{24,28–30,39,47,50} Studies pointed out that Australian culture is perceived to be ‘quite relaxed’²⁸ and ‘more open to discussing sexual health issues’^30,50 by refugee and migrant men, making ‘discussion of sexual health and HIV related issues appeared to be more acceptable’.²⁴ In their country of origin, however, refugee and migrant men ‘do not have courage to talk about sexual health – even with a doctor’.⁵⁰ This culture of shame and stigma regarding the discussion of SRH issues is identified to be a major barrier in discussing the topic freely with health care providers⁵⁰ and sexual partners⁴⁷ after resettlement in Australia. Botfield et al.²⁷ suggested that the culture of silence regarding SRH may constrain access to quality SRH information and care. We also identified intergenerational differences in SRH taboo from the literature included in this review.^28,30 For young men from refugee and migrant backgrounds, ‘attitude to talking about sex is more open’.³⁰ For older men, however, discussing SRH matters is ‘no man’s land’ and ‘no man speaks of it’.²⁹

Four studies identified stigma and discrimination, both at family and societal levels and mainly related to HIV/AIDS, as major barriers to testing and status disclosure at workplaces.^11,24,34,36 Men in one study explained that having HIV/AIDS means ‘you are odd from the family and they don’t care because you can still infect them’.²⁴ Due to the fear of stigma and discrimination, men in another study ‘haven’t talked to anyone in the company about these things [HIV status] and don’t want to talk to them’.³⁶ In addition, stigma and shame were associated with non-marital sex and sexual health issues, which presented a barrier to seeking knowledge and services.¹¹ The perceived association between HIV and same-sex sexuality/sexual practices also created barriers to accessing information and care.³⁴

Visa status and health insurance emerged as policy level factors that shaped access and utilisation of SRH care by refugee and migrant men.^9,32,33,39 For instance, some men on temporary work visas avoided HIV testing due to the fear that diagnosis would jeopardise future visa applications including to permanently stay in Australia.³⁶ In addition, men from countries that are ineligible for the reciprocal health care agreement had lower rates of early HIV diagnosis and treatment.⁹ Even if they are eligible for Medicare, some Iranian men in one study mentioned that ‘Just 10 consultation sessions [supported by Medicare] were not enough for those who have a serious [psychosexual] concern’.³⁹ This lack of adequate coverage through Medicare may have implications as reported by Ellawela et al.³², where not having private health insurance was associated with difficulty obtaining helpful contraceptive advice among Sri Lankan men living in Australia.

The purpose of this review was to synthesise the available evidence on refugee and migrant men’s SRH needs, understandings, and experiences of accessing services after resettlement in Australia. Mapping of the identified studies against the WHO SRH framework revealed that the majority of the 38 studies addressed men’s sexual health, mainly care related to STIs (HIV and hepatitis B). There were gaps in the literature on sexual function, psychosexual counselling, gender-based violence prevention, support, and care. The focus on STIs reflects the risk-based biomedical conceptualisation of health care. It may also reflect the focus of state hospital services on STIs and the paucity of services on male sexuality and gender based violence services.⁵⁹

The research about refugee and migrant men’s reproductive health has been restricted to understanding their perspectives on family size and attitude towards condoms and male hormonal contraceptives. The reproductive health literature also lacked viewpoints regarding other important components of fertility control including fertility/infertility care, safe abortion care, gender roles and joint reproduction and family planning decisions. In addition, the impact of forced migration, trauma and sexual violence on refugee men’s SRH during and after resettlement in Australia has not been explored. The identified research gaps should be addressed to develop effective, equitable and gender sensitive SRH programs for refugee and migrant men in Australia.

By applying the socio-ecological lens on the extracted data, we found that refugee and migrant men face multilevel barriers to access SRH care. At the individual level, the lack of access to and understanding of SRH information including on the availability of services emphasises the need for SRH education as part of resettlement programs.⁶⁰ Education and support should also be provided well after resettlement to address SRH issues that often arise later after the immediate issues of resettlement have been addressed. Gender differences in SRH literacy also suggest that programs need to be independently designed for men and women.¹⁶ This requires greater participation of refugee and migrant men in the co-design, delivery and evaluation of SRH programs. Addressing confidentiality concerns and the low uptake of interpreters is critical to overcome the interpersonal level communication barriers in SRH consultations with men from refugee and migrant backgrounds.⁶¹

Although we identified some barriers at organisational and policy levels, there was infrequent mention in the published literature how the organisation of SRH services in Australia and the National Men’s Health Policy 2010 affected refugee and migrant men’s utilisation of SRH services. This makes evaluating the impact of the policy on equitable SRH interventions, service utilisation and outcomes a necessity. Knowledge about the impact of the policy is required to facilitate and guide implementation of Australia’s Men’s Health Strategy 2020–2030, which prioritises both refugee and migrant men and SRH for possible interventions.

Overall, the findings of this review show that refugee and migrant men in Australia are underrepresented and generally marginalised in SRH program development, research conceptualisation, implementation and service delivery. Achieving the aims of Australia’s Men’s Health Policy¹³ and Men’s Health Strategy¹⁴ requires greater engagement of refugee and migrant men in SRH. This is important to enhance men’s access and use of SRH services to meet their own needs and aspirations.⁶² Engaging men is also critical to enable them equitably support their partners’ reproductive health and share responsibilities for healthy sexuality and reproduction.⁶³ This is significant as refugee and migrant women and health care providers in recent research have called for greater engagement of men in SRH care.^17,23 Furthermore, improved engagement of men in SRH is critical to promote and achieve gender equality and challenge harmful gender roles and attitudes that undermine women’s SRH autonomy and rights and discourage men from seeking care.^7,64 Evidence suggests that gender transformative approaches across the life span that operate at multiple levels of the socio-ecological environment and consider a broad approach to sexuality, gender and masculinities are effective in engaging men.⁷

This is the first systematic scoping review in Australia to synthesise the evidence on the SRH needs, understandings and experiences of refugee and migrant men, which can guide future research and programs. The use of the socio-ecological framework facilitated a systematic understanding of factors that shape refugee and migrant men’s SRH. It is valuable to mention that when presenting the results and discussing major findings, we chose to implicitly treat ‘refugee’ and ‘migrant’ men as essentially similar. Studies that involved both refugee and migrant men did not disaggregate results by refugee status, making it difficult to aggregate and synthesise results for these two groups. This may obscure important differences between and within the two groups (e.g. refugee men may have experienced trauma and sexual abuses in their asylum and resettlement journeys).

The review demonstrated that SRH research involving refugee and migrant men in Australia concentrated on the domains of STIs and HIV/AIDS and other aspects of both sexual health and reproductive health have not been sufficiently explored. This suggests the need to have a more comprehensive understanding of refugee and migrant men’s SRH needs and experiences. Specifically, further research should examine the influence of the National Men’s Health Policy 2010, state level men’s health policies and frameworks, and organisation of SRH care on refugee and migrant men’s access and experience in SRH care. Such knowledge is critical to guide the implementation of the National Men’s Health Strategy 2020–2030 and develop effective and gender sensitive SRH programs for refugee and migrant men at both national and state levels in Australia.

All relevant data are included in this manuscript.

The authors declare that they have no conflicts of interest.

No funding received for this project.

ZM and AJH conceived the review. ZM and AJH conducted the search and screened the titles with support from MB, JMU and JP. ZM, AJH and MB extracted and synthesised the data and drafted the manuscript. All authors reviewed, edited, and approved the final manuscript.