Abnormalities that are detectable early in infancy or are obvious at birth. These are also called congenital defects; they encompass both minor abnormalities, such as birth marks and more serious disorders such as spina bifida (failure of the spinal column to close properly). Birth defects can occur as the result of a variety of factors but in many cases no obvious cause can be found.
Some children are born with more or fewer than the normal 23 pairs of chromosomes. In Down’s syndrome there is an extra copy of one of the chromosomes, this is one of the most common chromosomal abnormalities.
Hereditary or genetic defects
These can be inherited from one or both parents. Genetic defects that are obvious at birth include albinism and achondroplasia (abnormally short stature).
Irradiation of the embryo at an early stage of development, for example if a woman is X-rayed before she is aware of her pregnancy can cause abnormalities.
If a woman contracts certain infections during pregnancy, there is a chance that this can cause birth defects. For example, rubella (German measles) in early pregnancy can cause foetal abnormalities, including cataract, deafness and heart disease. Toxoplasmosis (infection with a parasite found in cat faeces) can also be passed on to the foetus, creating damage to the eyes, liver and other organs.
Drugs and other harmful agents
Certain chemicals in drugs (known as teratogens) can damage the foetus if the mother takes or is exposed to them during early pregnancy. Teratogenic drugs include thalidomide (now rarely prescribed) and isotretinoin which is used in the treatment of severe acne. Alcohol can affect the development of the face or brain.
Other common defects
Abnormalities in the embryo’s development can affect the brain and spinal cord causing damage and defects such as spina bifida and hydrocephalus (a build up of fluid in the brain). In congenital heart disorders there is a structural abnormality in the heart that can interfere with normal blood flow. Cleft lip and palate result from the failure of the two sides of the foetal face and palate to join completely.
Blood tests and ultrasound scanning during pregnancy can help identify women at high risk of having a baby with a birth defect. Further tests such as chorionic villus sampling, fetoscopy or amniocentisis may then be carried out.
Certain birth defects can be prevented, or the risks minimised; for example by Rubella immunisation before pregnancy, (which has been known to cause autism in some children), folic acid supplement before and in early pregnancy and by avoiding teratogens during pregnancy.
A type of injury inflicted by the mouth parts of an animal, which can range from the puncture wounds of bloodsucking insects to the massive injuries, caused by crocodile or shark attacks. The teeth of carnivores can inflict widespread mechanical injury. Extreme injuries and lacerations to major blood vessels can lead to heavy blood loss and psychological shock. Serious infection can occur as a result of bacteria in the animals mouth being transferred in the bite, and tetanus is a particular danger. In countries were rabies is present, any mammal may potentially harbour the rabies virus and transmit it via bite.
Medical advice should always be sought for all but minor injuries and in all cases if there is a risk of rabies. The treatment usually includes examination and cleaning of the wound. The wound is usually left open and dressed, rather than stitched, as closing it can encourage the multiplication of bacteria. Anti biotic treatment and anti tetanus injection may also be given. If there is any possibility that the animal may be infected with rabies, antirabies vaccine is administered; people who haven’t previously been immunised against rabies are also given immunoglobulin.
Injuries caused by one person biting another. Human bites rarely result in serious blood loss or tissue damage; but infection from any microorganisms in the mouth is likely, particularly if the bite is deep. For example there is a risk of tetanus infection, and transmission of herpes simplex, HIV, hepatitis B and C.