Epidemiology, diagnosis, aetiology and knowledge about autism spectrum disorders (ASD) in Africa: perspectives from literatures cited in pubmed over the last decade (2000 – 2009)

Abstract

Background

The universal occurrence of ASD was queried about twenty-six years ago. It was thought to occur only in western industrialized countries with high technological development. Over the last decade, knowledge about ASD and its prevalence had been documented to be on the rise in different regions of the world with most literatures coming from the western world but the present situation in Africa on aspects of ASD remained unclear. Perspectives of literatures cited in pubmed over the last decade on aspects of epidemiology, diagnosis, aetiology and knowledge about ASD among Africans were assessed.

Methods

Key words like autism, diagnosis, aetiology, knowledge and Africa were variously combined in doing a pubmed search of literatures published over the last decade about ASD among Africans.

Results

No study addressed specifically epidemiology of ASD in Africa. One of the two studies that were relevant addressed epidemiology of ASD in Arab countries, though included two Northern African countries. Higher proportion of non-verbal cases of ASD compared to verbal cases was documented in literature coming from Africa. Associated co-morbid disorders included intellectual disability, epilepsy and oculo-cutaneous albinism. Aetiological factors postulated were post-encephalitic infection, genetic and auto-immune factors, vitamin D aetiological hypothesis among others. Knowledge about ASD in Africa was noted to be low.

Conclusion

There is need for epidemiological studies in Africa to define the magnitude of the problem of ASD and characteristics of children affected by ASD in this region. This would help in planning and might be helpful in answering the bothering question of aetiology of ASD. More policy making attention need to be directed at issues of childhood developmental disorders in Africa.

Background

About two and half decades ago, the universality of autism spectrum disorders (ASD) was put into question.¹ Autism spectrum disorders (ASD) was thought to occur mostly in Western civilized cultures and countries with high technological development.¹ Occurrence of ASD in Africa was then a subject of debate. Sanua¹ concluded then, that studies need to be done to address the open question of universality of ASD. Over the last decade and half, there had also been documented evidence of increase in prevalence and knowledge about ASD in other parts of the world.² The present situation in Africa as a continent on various aspects of ASD is unclear. It is on this background that this study looked at the perspectives of literatures cited in pubmed on various aspects of ASD over the last decades. The study assessed specifically aspects of epidemiology, diagnosis, aetiology and knowledge about ASD as documented in pubmed cited literature published on ASD among Africans over the last decade.

Methods

Key words like autism, diagnosis, aetiology, knowledge and Africa were variously combined to do pubmed search of literature published on topic of ASD in Africa over the last decade (2000 – 2009). A total of twelve (12) literatures published over the last decade on ASD among Africans fulfilled the inclusion criteria.^{3 – 14} They addressed various aspects of ASD like epidemiology, diagnosis, aetiology and knowledge among Africans and in African countries. Four of the literatures were coming from Nigeria, three from Egypt, two from Sweden and one each from Tunisia and Tanzania. Another one of the literatures focused on Arab countries, but with inclusion of Egypt and Tunisia as part of the countries where the study was conducted. Two of the twelve studies addressed the aspect of epidemiology as it is related to prevalence of ASD. Three studies addressed the aspect of diagnosis as it is related to symptoms presentation and associated co-morbidities. Six studies addressed the aspect of aetiology among African children, while two studies addressed the aspects of knowledge and awareness about ASD in Africa.

Table 1 showed the country or region of origin of the literatures and also various aspects of ASD addressed by these literatures.

Table 1.

Country or region of origin and various aspects of ASD addressed by the literatures included

Country or Region of Origin	Number of Studies	Aspects of ASD	Number of Studies
Nigeria	4	Epidemiology	2
Egypt	3	Diagnosis	3
Sweden	2	Aetiology	6
Tunisia	1	Knowledge	2
Tanzania	1
Arabs (Tunisia & Egypt)	1

Inclusion and exclusion criteria

Literatures related to aspects of ASD being assessed which were published prior to January, 2000 and those published either electronically or paper based publication after December, 2009 and cited in pubmed were excluded from the study. However, all studies published and cited in pubmed either electronically or paper based between January, 2000 and December, 2009 were included in the study.

Ethical consideration

Ethical approval for this study was obtained from the Institutional Review Board (IRB) of Federal Neuro-Psychiatric Hospital, New Haven, Enugu, Enugu State, Nigeria.

Procedure

Relevant information was extracted from the twelve literatures that fulfilled the inclusion criteria.

Results

Epidemiology

Two studies addressed aspect of prevalence of ASD among African children. Seif Eldin et al study³ was focused on Arab countries, but included two African countries which were Egypt and Tunisia in Northern Africa. Prevalence of ASD among children with developmental disorders in Egypt and Tunisia were documented to be 33.6% and 11.5% respectively by this study.³ Seif Eldin et al study³ employed the Modified Checklist for Autism in Toddlers (M-CHAT) as a screening tool. The other study, Barnevik-Olsson et al⁴ was not conducted in African continent. Barnevik-Olsson et al⁴ assessed prevalence of ASD among children born to Somali parents living in Sweden. They documented significantly higher prevalence of ASD among children of Somali parents living in Sweden compared to non-Somali group. Children of Somali parents living in Sweden were found to have a prevalence of 0.7% ASD compared with approximately 0.2% in non-Somali group. Barnevik-Olsson et al⁴ concluded that their findings warrant further investigation into why children of Somali parents living in Sweden tend to have higher prevalence of ASD, suggesting possible Vitamin D aetiological hypothesis among other factors might be responsible for this finding.

Diagnosis

Three studies^{5, 6, 7} fulfilled the criteria of providing information on diagnosis of ASD among African children over the last decade, as it relates to symptoms presentation and co-morbid disorders.

Symptoms presentation

Aside the core symptoms of ASD in the areas of impairments in social interaction, communication and restricted, repetitive repertoire of behavior, one common symptoms presentation that was found in over fifty percent of the cases reported in literature over the last decade was lack of expressive language (non-verbal cases). Belhadj et al⁵ reported 51.2% of non-verbal cases of ASD in their study. Mankoski et al⁶ observed about 71 % of non-verbal cases of ASD in their study, but they quickly concluded that this observation might be as a result of local diagnostic practice. The inference of these findings is that based on current diagnostic practice, the population of non-verbal cases diagnosed with ASD in Africa might be more than those who are verbal.

Co-morbidities

Among the co-morbid conditions diagnosed in association with ASD among African children documented in the literature over the last decade intellectual disability was more common. Belhadj et al⁵ documented co-morbid intellectual disability in over 60% of cases studied. Other documented co-morbid disorders in association with ASD among African children included Epilepsy⁵ and in one case, Oculo-cutaneous albinism.⁷

Aetiology

Six literatures addressed the aspect of aetiological factors for ASD among African children. Five of these studies based the proposed etiological factors on scientific methodologies^{6, 8, 9, 10, 11}, while one assessed the opinion of healthcare workers about the aetiology of ASD.¹² Common aetiological factors proposed for ASD among African children by these studies included post-encephalitic infection or sepsis preceding onset of symptoms of ASD⁶, genetic and auto-immune factors^{8, 10, 11}, vitamin D deficiency⁹. The only study that assessed the opinion of healthcare workers on aetiology of ASD documented a very significant proportion of 43 % of the healthcare workers subscribing to preternatural and supernatural aetiological factors for ASD¹², a finding further substantiating the inseparable spiritual beliefs of Africans and aetiological explanations of neuro-psychiatric disorders.

Knowledge about ASD

Two literatures addressed the aspects of knowledge about ASD in Africa. The findings of these two studies inferred that knowledge and awareness about ASD is still low in Africa, especially sub-Saharan Africa.^{13, 14} The studies^{13, 14} also concluded that continuous education of healthcare workers and the general public in Africa is of essence to raise the level of knowledge and awareness about ASD as improved knowledge would help in early recognition and intervention for African children with ASD.

Discussion

The debate raised about two and half decades ago that queried occurrence of ASD in Africa¹ had been put to rest to a large extent by literatures addressing aspects of ASD in Africa over the last decade. Based on the present update of knowledge, there is no element of doubt that ASD does occur among African children living both in Africa and abroad. However, many questions still remained unanswered about definitive prevalence, aetiology and characteristics of children affected by ASD in Africa, especially sub-Saharan Africa.

The two studies^{3, 4} that addressed aspect of epidemiology of ASD among Africans did not assess the prevalence of ASD in the context of population of children living in Africa. Seif Eldin et al study³ was specifically intended to study Arab countries and Barnevik-Olsson et al study⁴ determined prevalence of ASD among Somali immigrants living in Sweden.

The documented information about excess of cases of ASD who lack expressive speech (non-verbal cases) in the literature over the last decade^{5, 6} need to be subjected to verification in a large epidemiological study rather than clinic-based approach. Co-morbidity of epilepsy and intellectual disability in association with ASD found by the literature from Tunisia is an interesting finding⁵ as it corroborate the observation of Mankoski et al⁶ that ASD in Africa is rarely diagnosed exclusively of intellectual disability. The possibility also exist that more severe cases of ASD are likely to be referred to orthodox medical practice for help as majority of cases that are often less severe are likely to seek help from spiritualists and traditional healers, stemming from perceived etiological explanation of ASD among African healthcare workers as documented by a recent study.¹² Therefore, the relationship between ASD and intellectual disability among African children need to be further explored in an epidemiological study.

The proportion of children who presents with symptoms of ASD following post-encephalitic infection or sepsis as documented by Mankoski et al⁶ might be substantially higher among African children when compared to what obtains in most developed world and this may translate cumulatively to higher prevalence of ASD among African children compared to children from the western world. The hypothesis that pre-natal Vitamin D deficiency may contribute to aetiology of ASD as put forward by Barnevik-Olsson et al⁴ in the Sweden immigrant study would need further confirmation through epidemiological study of ASD in the tropical and subtropical regions of Africa where Vitamin D deficiency is likely to be rare because of availability of abundant ultra violet-B radiation from sunlight. On the other hand, the general population prevalence of ASD among African children may be lower than what had been found in the Western societies because of some certain environmental factors including the proposed Vitamin D aetiological hypothesis⁴. The proposition of Sanua¹, that ASD is a disease of western civilization and more prevalent in highly industrialized countries with high technological development may still hold true. Epidemiological data on ASD in sub-Saharan Africa children would not only reveal the present picture of ASD in this region, it would also help in further understanding the possible aetiological factors for ASD.

The low level of knowledge and awareness about ASD as documented by recent literature from Africa^{13, 14} is a call for engaging in activities that can improve the level of knowledge and awareness about ASD among healthcare workers and general populace in Africa. This would help early recognition of cases and interventions which had been shown to improve prognosis.^{15, 16} It would also help in changing the wrong perception of spiritual explanation for aetiology of ASD in Africa as found by another study.¹²

Child and adolescent mental health services, human resources and policy making in Africa

It is of import to pay attention to the recurrent theme of scarce child and adolescent mental health legislation, policies, services, programmes and human resources in Africa.^{17, 18} The need to scale up services to meet the challenges of child and adolescent mental health in Africa through mass education, personnel training, and appropriate policy formulation is imperative. The modalities stated by Patel et al¹⁷ in meeting the challenges of scarce resources in area of child and adolescent mental health in Africa and other low income countries is worth giving thoughtful consideration.

Conclusions

Studies need to be done soon, especially epidemiological studies to define the magnitude of the problem of ASD and characteristics of children with ASD in Africa, especially sub-Saharan Africa. These might be the tool for answering the bothering question of aetiology of ASD and may also shed light on reasons for possible differences in prevalence over geographical regions, if any does exist. Africa also needs more policy making attention directed at child and adolescent mental health service provision, especially the issues of childhood developmental disorders and intellectual disability in children and adolescents.