When a Diver Has a Fever

The last thing anyone wants to happen on a dive trip is that he or she becomes ill, but sooner or later it happens to all of us. A common manifestation of illness is elevated body temperature, which can range from being an insignificant indicator to a serious, debilitating problem. “Heat illness” refers to elevated body temperature attributed to environmental exposure and will be discussed in an upcoming article. Because many divers are parents who travel with children, I am including practical information for younger persons as well.

Fever is an elevation in body temperature most commonly caused by infection. It occurs because of a change in the thermoregulatory (temperature-controlling) center located in the brain. From an evolutionary perspective, it appears that fever may help fight infections.

If infection is present, the causative organism (most commonly a bacterium or virus, but also including certain parasites and other agents of disease) releases substances or causes the release of substances into the bloodstream that reach the part of the brain which acts as the body thermostat. Thus, body temperature is “reset” at a higher level. Some authorities believe that this may help to fight infection, but the temperature may need to be lowered if the elevation is extreme or prolonged, or if it contributes to functional debilitation.

What’s Normal?

Normal body temperature centers around 98.6˚F/ 37˚C measured orally and 99.6˚F/37.6˚C measured rectally. (To convert degrees Fahrenheit [F] into degrees Centigrade [C, or Celsius], subtract 32, then multiply by 5, then divide by 9. To convert degrees C into degrees F, multiply by 9, then divide by 5, then add 32.) Usually, body temperature is slightly lower early in the morning and higher in the late afternoon because of normal body rhythms, so a fever is considered morning temperature of greater than 98.9˚F/37.2˚C or a late-afternoon/evening temperature of greater than 99.9˚F/ 37.7˚C.

Although your mother may have determined that you had a fever by holding her hand against your forehead, temperature is properly measured with a thermometer. Electric (digital) thermometers are easiest to use and require the least time to record a temperature. If a mercury or alcohol thermometer is used, the thermometer should first be wiped down with rubbing alcohol or an antiseptic and then wiped dry. (This is important to help prevent the spread of disease.) It should then be shaken to pool the mercury or alcohol below the 94˚F/35˚C marking.

To take a temperature by mouth, the thermometer is placed under the tongue, the mouth is closed, and a reading is taken after three to four minutes. Advise the patient to be careful not to bite down on the thermometer. To take a temperature rectally (the more reliable method, although generally less preferred for aesthetic reasons), the thermometer is gently placed, ideally lubricated with oil or petroleum jelly, 1 inch/2.5 cm into the rectum. It is held in place for at least two minutes and then read. Never leave a child or confused adult unattended with a thermometer in the mouth or rectum.

An armpit (axillary) temperature is far less reliable because it may underestimate the temperature elevation. However, a high temperature recorded from the armpit may be interpreted to mean that there is some elevation in body temperature. An armpit temperature may be the only one you get in an uncooperative person. Since an axillary temperature tends to read on the low side, add 1.4˚F/.8˚C to obtain the equivalent rectal temperature.

What’s Not Normal?

Generally, an infection will not elevate the core (rectal) body temperature higher than 105˚F/40.5˚C. Persons who have temperatures measured above that level should be examined for heat illness, stroke or drug abuse. Vigorous, prolonged muscular activity (such as occurs with a seizure or marathon running) can raise the core temperature above 107˚F/41.7˚C.

For persons traveling with children, a child is considered to have a fever if his or her rectal temperature is greater than 100.4˚F/38˚C, oral temperature is greater than 100˚F/37.8˚C, or axillary temperature is greater than 99˚F/37.2˚C. One should be concerned about a fever greater than 100.4˚F/38˚C in an infant younger than 3 months of age or greater than 104˚F/40˚C in any small child, since the fever can indicate a severe infection. A physician should investigate prolonged fever in a child.

Chills are caused by the release of bacteria or viruses (or their toxins) into the bloodstream. The victim will suddenly feel very cold and begin to shiver, with teeth chattering, “goose bumps” and weakness. The “chill” may actually occur during a temperature spike within a fever.

A person suffering from a fever will often feel extremely tired. If the temperature gets very high, a person can suffer headache, back pain, drowsiness, loss of appetite, weakness or even delirium. A child who experiences a rapid elevation in temperature can suffer a seizure. Because fever may be accompanied by sweating and poor oral intake, it may contribute to dehydration, so drink lots of fluids when you have a fever.

Divers with fevers should consider common causes, such as infected cuts, bronchitis, severe ear infection, sinus infection or tonsillitis. Most fevers in healthy divers represent infections by common bacteria and viruses, and have the nature and duration of illnesses we suffer regularly at home. But travelers to foreign countries should keep their immunizations current (see sidebar) and be mindful of fever that develops while abroad — it may indicate a serious illness.

First Aid for Fever

If a person has a temperature higher than 100.5˚F/38˚C that is thought to be due to an infection, he will be made more comfortable by the administration of aspirin, ibuprofen (Motrin® or Advil®), or acetaminophen (Tylenol®). However, there are circumstances (such as dengue fever) where nonsteroidal anti-inflammatory drugs (such as ibuprofen) and aspirin should be avoided, so in general, acetaminophen is the best choice for a first-line antipyretic (antifever drug).

To avoid Reye’s syndrome (postviral abrupt abnormal brain function and liver failure), do not use aspirin to control fever in a child under the age of 17. Infants and small children with fevers (usually due to ear infections or viral illnesses) should be treated as soon as any elevation of temperature is noted to prevent febrile seizures. An infant (younger than 6 months) with a fever should be seen as soon as possible by a physician.

Sponging a child with cold water doesn’t help much to reduce fever and can even be counterproductive if the child struggles or begins to shiver, both of which generate heat. If the fever is greater than 104˚F/40˚C, sponging can be attempted using lukewarm water. Never sponge a child with alcohol, because it can be absorbed through the skin and act as a poison.

If a person suffers from environmental heat-induced illness, he will not benefit from and should not be given aspirin or acetaminophen.

When treating a fever, the label on most over-the-counter painkillers offers some of the best common-sense medical advice: “If a fever persists for more than three days or gets worse, or if new symptoms occur, consult a doctor, because these could be signs of a more serious condition.”

Update Your Immunizations

By some estimates, one in 20 people who travel abroad will suffer a fever, either during the trip or after returning home. Although most of these fevers are related to common illnesses, like an upper respiratory virus (such as a “cold” or influenza) or infectious diarrhea, there are other, more serious causes.

As a dive traveler, it is important to keep your immunizations current. Hepatitis A and B are common in many countries through which divers may travel and are particularly prevalent in “developing” or “third world” countries. Influenza (the “flu”) is considered to be present year-round in the Southern Hemisphere.

Common vaccines administered to travelers include those to prevent polio, measles, mumps, hepatitis A, hepatitis B, meningococcus, typhoid fever, cholera and yellow fever. Other measures to prevent certain diseases, such as preventive drugs against diseases like malaria and certain types of diarrhea-causing bacteria, are available. Ask your doctor about immunizations and other preventive measures that may be recommended when visiting remote, exotic dive destinations.

By Paul S. Auerbach, M.D.