Incidence and Prevalence

INCIDENCE AND PREVALENCE OF SPINA BIFIDA
Spina Bifida (L. Spilt spine) is a neural tube defect.
The world average of spina bifida has been estimated to be around 1 per 1000 population but marked geographical variations can occur. The highest rates are found in the British Isles, mainly Ireland and Wales where there is 3-4 cases of myelomeningocele per 1000 population with more than 6 cases of anencephaly per 1000 population.
France, Norway, Hungary, Czechoslovakia, Yugoslavia and Japan have a low prevalence is reported: 0.1-0.6 cases per 1000 live births.
In the US, a declining prevalence has been noted, with incidence higher on the East Coast than on the West. The prevalence in African Americans (0.1-0.4 per 1000) is lower than the white Americans (1 case per 1000)
Immigrants from Ireland have a higher prevalence of spina bifida than do nonimmigrants, suggesting a complex genetic relationship. A higher incidence is found in women than in men in anencephaly and an association has been reported with infertility and with antiepileptics (particularly valproate and carbamazepine).
US 1998, research indicates that folate can reduce the incidence of neural tube defects by about 70% and can also decrease the severity of these defects when they occur.
Due to current fortification programs in US, around 22, 000 cases or 9% of the estimated folic acid-preventable spina bifida and anencephaly.
The most common type of spina bifida is spina bifida cystica (myelomeningocele) accounting for 94% of the cases.
Occurance is higher in first and second degree relatives of affected infants than to the general population.
Australia has a mandatory folic acid fortification program which is in wheat flour for bread making within the prescribed range of 200-300 µg per 100 g of flour. In Australia, between 1998-2005, the average prevalence was 4.6 per 10000 births. Incidence in younger women pregnancies were higher than in older women. (Australia Government: Australian Institute of Health and Welfare)