Fever is defined as a temporary rise in the temperature of the body in response to infection or illness, while convulsion is a medical condition where a person's body shakes rapidly and uncontrollably due to repeated contraction and relaxation of the muscles. Occasionally, fever and convulsions occur together. This condition is known as febrile seizure. Age and family history play an important role in the occurrence of febrile seizures, and these seizures are more common in children under five years of age.
Infections
As the blood cells of the infected individual fight the infection, there is an increase in the white blood cell count. This causes the hypothalamus--the temperature regulating portion of the brain--to increase the body temperature. Increased temperatures, especially in children, decrease the amount of certain proteins on the nerve cell membrane, resulting in increased muscle activity and convulsions.
Fever accompanied by convulsions occur commonly in infections of the brain and spinal cord such as meningitis and encephalitis. Other infections associated with febrile seizures include otitis media (ear infection), respiratory tract infections such as pneumonia caused by viruses, urinary tract infection, gastroenteritis (inflammation of the digestive tract) and influenza. An infection of the lymph nodes, known as roseola, is caused by a virus called human herpesvirus 6 and is commonly associated with fever and convulsions.
Vaccinations
Several vaccines like the diphtheria, pertussis and tetanus (DPT) vaccine, flu vaccine and mumps, measles rubella (MMR) vaccine are commonly associated with convulsions and fever in children. According to the British Department of Health, for every 100,000 children who receive the MMR vaccine, 25 to 34 children will experience febrile seizures, while 6 to 9 children will experience this condition for every 100,000 children who receive the DPT vaccine. Some countries like Australia and New Zealand have banned some influenza vaccines due to the high incidence of fever and convulsions in children.
However, most of these incidents of fever and convulsions are mild and do not lead to any brain damage. The risks posed by conditions like measles and flu are far greater than those associated with febrile seizures. Thus, although a parent has to be aware of these side effects, the child's vaccination schedule should be completed.
Genetics
The exact genetic component for susceptibility to fever and convulsions is unknown. However, Dr. Saleh F. Al-Ajlouni of King Hussein Medical Center, Jordan, notes in a review article published in a 2000 edition of "Neurosciences Journal" that siblings of children who frequently have febrile seizures have a 1 in 5 chance of being susceptible. If both the parents also have a history of these conditions, then the child has a 1 in 3 chance of getting them. The seizure incidence in offspring of individuals with a history of febrile convulsions is 10%.
