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Why Infants Often Get Fever?

Fever is a sign of interaction between antigen and the host's defense mechanism. The body maintains normal core body temperature at a set point of 37°C (98.6°F), within a narrow range of 1 - 1.5 °C. Heat generation (increased cell metabolism, muscle activity, involuntary shivering) and heat conservation (vasoconstriction, heat preference behavior) are balanced against heat loss {evaporation-radiation-convection-conduction), vasodilatation, sweating and cold preference behavior.

Auxiliary temperature may be 1°C lower than core temperature. When a rise in temperature is not associated with tachycardia, chills, and sweating, a fictitious fever should be suspected.

Normal body temperatures in a well child can range from 97.7 degrees F / 36.5 degrees C to 100 degrees F / 37.8 degrees C. Babies have higher temperatures than older children, and everyone's temperature tends to go up during the day and down after midnight. In general, a baby isn't considered feverish unless her temperature is over 100 degrees F / 37.7 degrees C in the morning or over 101 degrees F / 38.2 degrees C in the evening.

There are three types of fever:

a) Continued-the fever does not fluctuate more than 1DC(1.5°F) during the 24 hours but never touch base line;

b) Remittent-when the daily fluctuation exceeds 2°C and does not touch the base line;

c) Intermittent- fever is present only for several hours during the day and touches the base line. When a paroxysm of intermittent fever occurs daily, the type is quotidian; when on alternate days, tertian; when two days intervene between consecutive attacks, quarten.

Normal 36.6 - 37.2 °C or 98-99°F
Subnormal below 36.6°C or below 98°F
Hypothermia below 35 C or below 95°F
Febrile above 37.2°C or above 99°F
Hyperpyrexia above 41.6 C or above 107°F

But turning up the temperature can have a down side: in about one in 25 infants or small children, high fever can trigger fever-induced (febrile) seizures. While the seizures themselves are generally harmless, a prolonged fever resulting from infection or heatstroke of over 108 °F (42 °C) can eventually lead to respiratory distress, cognitive dysfunction, brain damage or death.

The antigens either infectious or noninfectious induce the production of endogenous pyrogens such as interleukins (IL-I?, IL-l?, 1L-6), tumor necrosis factors (TNF-?, TNF-?) and interfern-?, induce fever within 10-15minutes. The cytokines directly stimulate the hypothalamus to produce prostaglandin E2, which then reset the temperature regulatory set-point; then neuronal transmission to the periphery leads to conservation and generation of heat, thus raising core body temperature.

In fact, an infant under two or three months of age may have a serious bacterial infection, such as meningitis (an infection of the fluid surrounding the brain and spinal cord), bacteremia (a blood infection), or a urinary tract infection and still appear totally fine. That is why doctors routinely do a septic work-up on infants who are under two or three months old when they have a rectal temperature that is at or above 100.4°F.

The measles virus causes a rash, cough, runny nose, eye irritation and fever, but it can also lead to ear infections, pneumonia, seizures, brain damage, and rarely, death. The mumps virus causes fever, headache and swollen glands, but it may also cause deafness, meningitis, painful swelling of the testicles or ovaries, and rarely, death. The rubella virus causes a rash, mild fever and arthritis, but in pregnant women, it can lead to a miscarriage or birth defects, according to the CDC.

Heat production associated with fever, increases oxygen consumption, carbon dioxide production, and cardiac output. Further children between the ages of 6 months and 5 years are at increased risk of benign febrile seizures.

Fever is a symptom, not a disease. Fever helps fight harmful infections by activating the body’s immune system. At birth, the capacity of the immune system to defend against infectious pathogens is not fully developed. The capacity increases during the early months and years of life, with this evolution most pronounced during the first two to three months.

Infants who experience fevers before their first birthday are less likely to develop allergies by ages six or seven, according to a new study funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH). In particular, fever-inducing infections involving the eyes, ears, nose or throat appeared to be associated with a lower risk of developing allergies, compared with similar infections that did not result in fevers.

High body temperature not caused by hypothalamic regulatory mechanism may be due to:

i) Increased indigenous heat production (vigorous exercise, malignant hypothermia, neuroleptic malignant syndrome, hyperthyroidism),

ii) Decreased heat loss (wrapping in multiple blanket layer, atropine intoxication) or

iii) Prolonged exposure to environmental temperature (heat stroke).

Drug fever not always associated with skin rash, eosinophilia, drug allergy and usually resolves within 24 hours of stopping the drug. The common drugs are penicillin, cephalosporin, phenytoin, carbamazepine, methyldopa etc.

Hyperpyrexia: The cause may be severe infection, hypothalamic disorders or central nervous system hemorrhage and put the patient at higher risk of brain damage.

Management:

The aim is to keep the temperature at a level that the child feel comfortable and specific treatment for the cause of fever, maintain hydration and nutrition.
Most children are comfortable until their temperature reaches 38.5°C; antipyretic is not indicated below this temperature.

The environment should be cool and airy and clothing bare minimum. Gentle message may lower the temperature through cutaneous vasodilatation.
Hydrotherapy: A towel soaked in luke warm water, rinsed, and sponge the body. Paracetamol in a dose of 10-15mg/kg/dose may be used to reduce temperature and no more than 6 doses should be administered in 24-hours.
Hyperpyrexia: Immersed the body in ice cold water, rectal temperature to be monitored continuously and continue the therapy till temperature comes down to 38"C. During the hydrotherapy, a lytic cocktail of very small doses of chlorpromazine, promethazine and pethidine may be given intravenously at intervals of 30 minutes to reduce shivering and rebound rise of temperature.

Because a fever can occur with many different conditions, other signs and symptoms can often help identify the cause. If you don't know why you have a fever, it's best not to try to lower your temperature. This may only mask your symptoms and make it harder to determine the cause. In addition, some experts think that aggressively treating all fevers actually interferes with your body's immune response. That's because the viruses that cause colds and other respiratory infections thrive at cool temperatures. By producing a low-grade fever, your body may actually be helping eliminate the virus. What's more, most fevers go away in a relatively short time — usually within a few days.

Studies have found that the presence of a minor to moderate illness such as an upper respiratory tract infection, ear infection, skin infection, fever or diarrhea does not compromise a child’s ability to respond to vaccines or increase the risk of an adverse vaccine reaction.”

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