Epidemiology: prevalence
Seven publications (6 cross-sectional, 1 follow-up study) contained epidemiological data on prevalence for South Africa, Zimbabwe, Tanzania and Nigeria, as shown in Table
1. The prevalence of albinism from these studies ranged from as low as 1 in 15,000 in the East Central state of Nigeria [
8] to as high as 1 in 1,000 in the Tonga tribe of Zimbabwe [
9]. A paper from Cameroon [
10] lacked clarity in its study design making the epidemiological data difficult to interpret. Generally, albinism is considered to be a relatively common hereditary condition among the southern African populations.
Table 1
Estimated prevalence and number of people with albinism by country
Kromberg et al.(11) | South Africa/45,026,000 | Cross-sectional study. Subjects were ascertained through all 120 schools, 6 health clinics and 2 hospitals in Soweto and interviewed; 213 albinism cases found; 206 interviewed | 1/3,900 | 11,545 |
Venter et al. (12) | South Africa/45,026,000 | Prospective hospital based study on liveborn neonates in Sovenga; 5 albinism cases | 0.66 per 1,000 live births (Incidence) | 29,720+
|
Kagore et al. (14) | Zimbabwe/12,835,000 | Postal survey of all secondary schools within the Harare regional office area; second mailing in 3 months; visited, if there was no response | 1/2,833 | 4,531 |
Lund (13) | Zimbabwe/12,835,000 | Nationwide survey to schools; age range of 6–23 yrs; 278 albinism cases | 1/4,728 | 2,715 |
Lund et al. (9) | Zimbabwe/12,835,000 | Follow up on the above study which identified a cluster of OCA2# in Tonga community; 11 albinism cases; 5 adults and 1 school girl were interviewed | 1/1,000 | --- |
Luande et al. (17) | Tanzania/36,977,000 | Cross-sectional study. Questionnaire to 350 registered people with albinism in Tanzania Tumor Centre | 1/1,400 | --- |
Okoro (8) | Nigeria/124,009,000 | Cross-sectional study. Questionnaires distributed to people with albinism who came to the hospital; expanded the study to educational, health, religious institutions and markets in East central state; 517 albinism cases | 1/15,000 | 8,267 |
South Africa
In 1982 Kromberg et al. studied prevalence in the ethnic groups in Soweto and Johannesburg, South Africa. 206 individuals with albinism were surveyed and the 1970 census data for Johannesburg (803,511) was used to calculate the overall prevalence of 1 in 3,900 [
11]. In terms of ethnicity, the prevalence was lowest (1/4,794) among the Xhosa people and highest (1/2,041) in the Southern Sotho population. Albinism prevalences among the Swazi (1/2,716) and the Tswana (1/3,481) were slightly lower [
11].
High prevalence does not seem to exclusively occur in urban regions. A prevalence of 1 in 1,515 was reported from a prospective study of congenital anomalies of liveborn neonates in Sovenga, a more rural region in Northern Transvaal, South Africa [
12]. This is somewhat higher than the national rate of 1 in 3,900 [
11].
Zimbabwe
A school-based study in Zimbabwe ascertained 157 albinism cases among 772,758 primary school pupils, giving a prevalence of 1 in 4,922. Similar results (1/4,476) were found among secondary school students. However, there was a substantial difference in the prevalence when the data were analysed by provinces: the prevalence in Matabeleland South (1/7,539) was only half of that found in Mashonaland East (1/3,843) [
13].
Similar to South Africa, there was also a sizeable difference between rural and urban populations in Zimbabwe, most of which was due to Harare's high prevalence of 1 in 2,792 and 1 in 2,661 in the primary and secondary schools, respectively. Overall, urban schools, including Harare, had a prevalence of 1 in 3,268 compared to 1 in 4,694 in the rural schools [
14]. As mentioned previously, an extremely high prevalence of 1 in 1,000 was reported among the small Tonga tribe, who resides in an isolated rural community of Zimbabwe [
9].
Tanzania
Although there have been some studies addressing the health conditions of people with albinism in Tanzania, the data available on prevalence are not as extensive as for South Africa or Zimbabwe.
A study of individuals with albinism who were registered in the Tanzania Tumour Centre in Dar-es-Salaam estimated a prevalence of 1 in 1,400. However, this estimation is difficult to extrapolate to the entire population, given the data's limitation only to those individuals enrolled in the registry [
17].
Nigeria
Nigeria's data on the epidemiology of albinism were also sparse. A prevalence of 1 in 15,000 has been reported for the East Central state through a study investigating people with albinism attending the hospital with dermatological problems. To these individuals, a questionnaire concerning demographical information such as age and gender as well as knowledge of other persons with albinism was distributed. Then, the authors expanded the investigation to educational, health and religious institutions and markets in order to reach a broader population [
8]. The prevalence in this study is considerably lower than what has been reported for the other countries, but comparisons are hampered by the study design employed.
Regional differences: urban vs. rural
Findings of higher prevalence in urban areas may be due to various factors. Given the higher population density, it may have simply been more feasible to collect comprehensive data from urban areas. Migration to urban areas for education, health care and indoor occupations may also be contributing factors.
In addition, since many of the studies were school-based, one must consider the role of attendance. For example, urban families may have a greater ability to send their children with albinism to school. There may be more schools in urban areas that accommodate for the visually disabled and for the UV protection needs of this population. On the other hand, some families may only be able to send one or a limited number of children to school, in which case it is possible that the affected child will not be chosen in the majority of families. All of the above situations introduce bias into the prevalence estimates.
Regional differences: ethnicity
Ethnic differences also influence prevalence estimates. In Zimbabwe, given that the majority (83.1%) of people with albinism belonged to the Shona tribe, the diversity in the observed prevalence may be due to a founder effect or genetic drift since the Shona population have generally limited their residence to southern Africa [
14]. Kromberg et al. also reported similar variations in South Africa [
11].
Aside from the limited geographic mobility, consanguinity, along with other traditional marriage practices, may also be factors to consider in evaluating current and future prevalence trends of albinism [
6,
8,
9,
11].
Life expectancy and mortality
Several publications report a relatively greater number of individuals with albinism in the younger age groups (below 30 years). In the East Central state of Nigeria, 89% of identified people with albinism were in the age range of 0 – 30 years [
8] while another study reported that 77% were under the age of 20 in the same Nigerian state [
15]. A mean age of 17.8 years was reported in Soweto, South Africa [
16].
Also in Cameroon, Nigeria and Tanzania, observations indicate a low number of people with albinism in age groups above 30 [
8,
10,
17].
Whether this truly points to an increased mortality of people with albinism at a younger age (less individuals reach higher age groups) could only be evaluated on the basis of more specific mortality data. However, such data are missing.
Psychological and social issues
In addition to their health concerns, people with albinism must also deal with psychological and social challenges. In Nigeria, one study collected written accounts of people with albinism. These individuals stated that they tended to be more withdrawn from social situations to avoid being noticed. They were more emotionally unstable and had less assertive personalities than people without albinism. Also, they considered their society to be generally unkind and rejecting, even though they did have close friends [
4].
Much of the social discrimination appears to stem from the communities' lack of education about albinism's etiology. There is limited awareness of its genetic inheritance and therefore, traditional myths and superstitions are numerous [
6]. For example, some of these beliefs link albinism with (culturally unacceptable) conception during menstruation or consider albinism as a punishment from the gods for an ancestor's wrongdoing [
8]. Due to this socially rooted discrimination, the quality of life of people with albinism may be compromised. For example, they are more likely to drop out of school and face more difficulty in employment and marriage compared to the rest of the population.
Furthermore, their family members may also experience discrimination from the community. In light of the traditional myths concerning albinism's etiology, mothers of affected children may be subjected to a great deal of stigma and psychological distress.
WHO albinism pilot survey results
WHO drafted and distributed a survey (see
Additional file 1) to the African WHO Member States enquiring about information on the epidemiology, medical and social issues affecting people with albinism. The survey was intended to provide a qualitative overview of these issues in the countries concerned.
The following 12 countries returned surveys: Cameroon, Congo, Equatorial Guinea, Ghana, Guinea Bissau, Mali, Mauritius, Mozambique, Niger, Rwanda, Sao Tome and Principe, and Tanzania. Respondents were either medical doctors affiliated with the Ministry of Health (Cameroon, Congo, Ghana, Tanzania) including dermatologists (Mauritius), Ministry of Health officials (Mozambique, Niger), WHO Country Officers (Guinea Bissau) or NGO personnel/other (Congo, Equatorial Guinea, Mali, Rwanda, Sao Tome and Principe).
We distributed three language versions of the WHO Pilot Survey: English, French and Portuguese. Among the survey responders, the Francophone countries included Rwanda, Niger, Mauritius, Mali, Equatorial Guinea, Congo, Cameroon. The Anglophone countries included Ghana and Tanzania and the Lusophone countries included Sao Tome and Principe, Mozambique and Guinea Bissau. The countries were divided into Francophone, Anglophone and Lusophone groups purely on (official) language grounds. There was no intent to use this grouping for comparative analyses.
Prevalence data were unavailable for the majority of the countries. A few countries did report the prevalence of albinism, but there was much variation and, in comparison to published data, the reported high estimates appeared somewhat unrealistic. Furthermore, the data sources of these estimates were not specified.
In terms of health care, survey respondents felt that much more needs to be done to address the needs of people with albinism. None of the countries, aside from Tanzania, had specialized clinics to handle the dermatological consequences of albinism. Five countries (Sao Tome and Principe, Mozambique, Mauritius, Congo and Tanzania) reported that they provide some advice on UV radiation protection for people with albinism in clinics and hospitals. Overall, however, the care was felt to be incomprehensive due to the lack of medical personnel's awareness of albinism, discrimination against people with albinism and/or a lack of resources such as sunscreens. Also, the aid was only provided if actively sought. This passive approach raises concern considering many persons with this condition may not seek regular medical attention.
Most of the surveys reported a lack of trained medical personnel. Challenges to better health care also included the barriers existing among the health workers in approaching people with albinism (lack of sensitization), lack of finances and education among this population, high cost of protective products such as sunscreens and hats/medications and social preconceptions and marginalization. Seven of the surveyed countries (Congo, Equatorial Guinea, Guinea Bissau, Mali, Niger, Sao Tome and Principe, Tanzania) reported the use of traditional medicines by people with albinism. However, the information in the survey was limited and it could not be substantiated whether people with albinism use traditional medicines differently from the general population, both in terms of frequency and rationale.
The discrimination of people with albinism is not only limited to the health care arena. The surveys report a great amount of stigmatization in schools from fellow students and teachers and even within their own families. Stigmatization stems from traditional explanations of albinism of which there are many (see above) [
8]. In addition, the curiosity of their different skin colour plays a role. Most countries reported a lack of knowledge about this health condition among the general public. Survey respondents also felt that many people with albinism did not fully understand their own condition. This social discrimination was seen as an obstacle to building relationships and finding/maintaining an occupation. Therefore, most people with albinism were generally reported to be of lower, if not the lowest, economic status in their society.
In light of these difficulties, it is not surprising that many surveys reported abuse and psychological problems within this population.
However, there is some evidence of social support for people with albinism. This includes dedicated NGOs such as "SOS Albinos in Mali" and "SOS enfants vulnerables sans frontiers" in Congo. Tanzania and Congo reported that children with albinism who have visual difficulties may enroll in specialized schools for the blind. Community outreach programs exist in some surveyed countries (Congo, Cameroon and Tanzania).