The links do say that some of the children who are born with this condition are *stolen* or taken away from their families by organised crime. If there seems to be a large concentration of such children in one town or district, it might be that they were not necessarily born in that area and may have been brought in from outlying villages etc.. I might be making a generalisation but I expect that literacy and the recording of births etc. in rural areas will not be on par with major towns/cities in Pakistan so pinpointing where the children are coming from would also be problematic.
So this type of scenario would no doubt distort gaining true figures or statistics or indeed reasons as to what may be the underlying cause of the conditions, i.e. if it was indeed environmental or a genetic condition.
It also isn't that unknown for mothers to unwittingly take certain chemicals/medications which will affect their child. For e.g. the birthrate of people with physical deformities from Thalidomide is rising again in the Third World as it is being prescribed for leprosy cases etc.. Microcephaly (which is what these children/adults all have in common) can be acquired as well as being a genetic condition.
This
site (from one of many on a Google search) lists the causes of Microcephaly:
exposure to hazardous chemicals/substances
exposure to radiation
lack of proper vitamins and nutrients in the diet
infection
prescription or illegal drug and alcohol consumption
maternal diabetes
Also:
Microcephaly can occur alone or in association with other health problems, and may occur from inheritance of an autosomal recessive, or rarely, an autosomal dominant gene. Acquired microcephaly may occur after birth due to various brain injuries such as lack of oxygen or infection.
I'm not able to say what causes the condition, whether it is hereditary, deliberate etc.. I would hazard that in some rural areas, the lack of a nutritious diet for the mother could well be a likely factor in bringing about the condition of some of the children, having checked out the demographics and stats for Pakistan on the Unicef website.
I'm actually more curious as to why the children are surviving in a country where the infant mortality rate is high, rather than the actual cause of the condition. I find this to be interesting.
There could well be the organised crime element that is injuring children or parents deliberately taking chemicals etc. in order to have a disabled child. Such a child may increase the family finances as the cultural
and religious beliefs of the region states that the child is blessed or closer to God/s. Pretty much the same with Indian Brahmins or Buddhist monks I believe, no one can turn them away empty handed as it will bring about bad luck. The children are successful at begging because of the belief that they are holy. Which seems to be the case at the temple cited in the OP's first link. I should also think this accounts for the high survival-after-birth rate that appears to be going on for people with this condition.
Not because of *holy* intervention though.
What might account for the high stats for people with Microcephaly, compared to other regions in the area is that these children would be receiving slightly better care and attention due to the belief that they are holy and/or money earners. Also, there would be minimal genetic screening and/or option of abortion as is practiced in the West.
They will also no doubt be marked out as the family's future big-money breadwinners, improving their chances of survival in an area of the world where again, the infant mortality rate is still significantly high. So I would probably hazard again, one of the reasons as to why there is a perceived *high* population of rat-headed children in that area of Pakistan is mainly due to the apparent fact that they are *useful*, in that they can be exploited financially so are better cared for from birth than if they were seen to be *useless* in that they could never tend a field, learn to read or write etc..
edited: reason? my dumbass spelling and grammar