Microcephaly Epidemiology

Microcephaly is a condition that causes smaller than average head in an affected baby or infant. The disease is either congenital or acquired but it cannot be cured. Patients tend to have an underdeveloped brain which leads to neurological issues or other complications. If the disease is diagnosed early, medical staff can put in place actions to limit any further damage to the developing infant’s brain and abilities.

Microcephaly is still a rare condition worldwide although there have been surges in the numbers of cases in specific countries. Globally, 1 in every 30,000 to 250,000 babies has microcephaly at birth. In the United States, this is about 2 per 10,000 to 12 per 10,000 of live births. In the UK, there are 1.02 cases of microcephaly per 10,000 births.

Various congenital conditions such as familial autosomal recessive defects, autosomal dominant disorders, and Down’s syndrome can cause microcephaly. Continuous and single gene deletions can have an impact too. Doctors usually investigate the baby’s family history to determine whether the observed microcephaly is due to heritage.

The condition can also be linked to viruses such as Rubella, chicken pox, and cytomegalovirus of the herpes family, and can put an infected pregnant mother’s baby at an increased risk of the disease. The health of the mother also plays a part. Malnutrition and the lack of essential vitamins and nutrients for the growing fetus can lead to microcephaly making it a potentially higher risk in populations with limited supplies of food.

There has been a recent surge of microcephaly cases in some countries. On average, the state of Pernambuco in northeast Brazil reports about 10 cases of microcephaly a year. However, from the beginning of January 2015 to November 2015, 141 cases were reported in 44 of its 185 municipalities. Similarly, Rio Grande de Norte saw an uncharacteristic rise in microcephaly from August 2015 to 16 November 2015 with 35 cases reported.
This compares to an average of 163 cases with a standard deviation of 16.9 every year nationwide between 2010 and 2014.

Scientists are investigating whether the cases are connected to an increase in Zika virus infections in the region. This infection is transmitted by mosquitoes and is believed to cause microcephaly in babies of infected mothers. Many of the mothers of affected babies were reported to live in a Zika affected area or to have visited a Zika affected area during pregnancy.

References

• http://www.cdc.gov/mmwr/volumes/65/wr/mm6503e2.htm
• http://www.who.int/csr/don/27-november-2015-microcephaly/en/
• http://www.paho.org/hq/index.php?option=com_docman&task=doc_view&Itemid=270&gid=32879&lang=en
• http://ecdc.europa.eu/en/publications/Publications/communicable-disease-threats-report-21-nov-2015.pdf