27 Devastating Infectious Diseases
What Is Considered A Fever—and When To Get Medical Attention
ArtistGNDphotography / Getty Images
A body temperature of 100 to 100.4 degrees is considered a fever, medically known as pyrexia, in adults. An oral temperature of 99.5 degrees or a rectal temperature of 100.4 degrees is considered a fever in a child or infant. Normal body temperature is typically 98.6 degrees.
A fever is a common COVID-19 symptom. However, the only way to know if COVID is the cause of your fever is to receive a test.
A fever is a higher-than-normal body temperature. Your average body temperature varies but is usually about 98.6 degrees. Some evidence suggests that the average body temperature has dropped to 97.9 degrees over the last two centuries. A fever may be different in adults, children, and infants: Adults Children (rectally) Children (orally) Children (axillary) Infants (rectally) 100 to 100.4 degrees 100.4 degrees 99.5 degrees 99 degrees 100.4 degrees What Is a Low-Grade Fever? A low-grade fever is a body temperature above normal but not above or just barely above the fever threshold. A low-grade fever typically ranges between 99.1 and 100.4 degrees in adults and children. A low-grade fever in infants, which is slightly elevated but not quite 100.4 degrees, may be a sign of a mild infection. Fever symptoms typically depend on how high your body temperature is. Fevers can be cyclical, meaning they go up and down. You may begin to sweat when a fever breaks or comes down. Some of the most common signs and symptoms of a fever include: Chills Flushed skin that is warm to the touch Increased heart rate Muscle spasms Sweating (e.G., night sweats) Infants and children may show other signs and symptoms of a fever, such as: A lack of appetite Earache (e.G., a child may pull at their ears) Fussiness, high-pitching crying, and whimpering Painful, swollen joints Pale skin Severe headache Skin rash Sore throat Swollen soft spot on an infant's head Upset stomach A fever is not a disease but typically means your body is fighting an infection. Bacteria and viruses that cause infections thrive at normal body temperature. A fever results from your body trying to get rid of the invader by making your body an inhospitable environment for it. A fever starts an immune response, which defends you against the invader. Autoimmune disorders, early-stage cancer, heat illness, and some medicines (i.E., antibiotics) may also cause a fever. Children sometimes develop a low-grade fever after getting a vaccine. A fever may be present if you are hot to the touch, feel feverish, have chills and flushed skin, or look glassy-eyed. The best diagnostic tool for determining if you have a fever is a body temperature reading using a digital or electronic forehead thermometer. To take your temperature orally: Clean your thermometer with cool water and soap or rubbing alcohol Place the thermometer under your tongue, then close your mouth. Hold it in place using your lips. Do not bite down on the probe. Keep the thermometer in your mouth for three minutes or until it beeps Clean your thermometer once you are finished You can take your temperature axillary by placing the thermometer under your armpit for five minutes. Other methods include electronic ear thermometers and plastic strips that change colors if you have a fever. These methods are typically less accurate than a digital thermometer. Infants and Children Take an infant or young child's temperature rectally (in their bottom) since they cannot hold a digital thermometer firmly in their mouths. Keep a separate digital thermometer for rectal temperatures and label it as such. You can also take a child's temperature axillary or orally. To take a rectal temperature: Clean your thermometer with cool water and soap or rubbing alcohol Apply petroleum jelly to the probe of the thermometer Lay your infant or child across your lap and on their stomach Place the thermometer about half an inch into your infant or child's rectum, stopping if there's resistance Keep the thermometer still while it takes the temperature. Remove it after three minutes or once it beeps. Clean your thermometer once you are finished Do not bundle up an infant or child in blankets or clothing or bathe them before taking their temperature. You may raise their body temperature, resulting in an inaccurate reading. Do not leave an infant or child alone with a digital thermometer, which may be a choking hazard. A slightly elevated body temperature is not typically a cause for concern. You may want to take steps to lower, rather than suppress, your fever. Here are a few things you can do to help make yourself comfortable while the fever runs its course: Avoid bundling up in blankets or excess clothing Do not force food if you or your child do not have an appetite, but eat if you are hungry Get plenty of rest Keep your room comfortable. Use a fan to cool down the room if it's too hot. Stay hydrated with gelatin, ice pops, soup, and water Take fever reducers like Advil (ibuprofen) and Tylenol (acetaminophen). Follow the instructions on the label for using fever reducers. Do not give Advil to an infant younger than 6 months or aspirin to a child younger than 18. Follow the label instructions to give your infant or child the correct amount of medicine. Contact a healthcare provider if your infant is younger than 3 months before you give them medicine. Use a device, such as a syringe, to measure how much liquid medicine to give your child. You may give your child Children's Tylenol and then give them a warm bath. Without medicine first, a bath may cause shivers and raise your child's temperature. In certain cases, you may need to contact a healthcare provider about your fever. Reach out to a healthcare provider if: You have a fever of 105 degrees or higher, unless it comes down easily with home treatment and you are comfortable You have a fever persistently at 103 degrees or a fever that continues to rise above 103 degrees Your fever persists for longer than 48 to 72 hours Contact a healthcare provider if your infant or child: Is 12 months or older and has a 105-degree or higher fever that does not go away with home remedies Is 3 months or younger with a rectal temperature of 100.4 degrees or higher Is 3 to 12 months with a 102.2-degree or higher fever Is 2 years or younger with a fever that does not go away after 24 to 48 hours Is older than 2 years with a fever longer than 48 to 72 hours Call a healthcare provider right away if you or your infant or child have: A cough, earache, or sore throat (for infants and children) A fever that comes and goes for one week or longer A weak immune system (i.E., due to cancer treatment or spleen removal) An underlying health condition (i.E., a chronic lung problem, diabetes, and heart disease) New bruises or rash Pain while urinating Recently been vaccinated (for infants and children) Recently traveled abroad A fever is typically a sign of an illness or infection, such as COVID. Healthcare providers generally consider a body temperature of 100 to 100.4 degrees a fever in adults. Infants and children have a fever if they have an oral temperature of 99.5 degrees or a rectal temperature of 100.4 degrees. Mild fevers typically resolve with home remedies, like getting plenty of rest and staying hydrated. However, follow recommendations, depending on your or your child's age and severity and duration of the fever, for when to reach out to a healthcare provider.Thanks for your feedback!
13 Sources
Health.Com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Dinarello CA, Porat R. Pathophysiology and treatment of fever in adults. In: Spelman D, Hall, KK, eds. UpToDate. UpToDate; 2024.
Smitherman HF, Macias CG. The febrile infant (29 to 90 days of age): Outpatient evaluation. In: Teach SJ, Kaplan SL, Wiley JF, eds. UpToDate. UpToDate; 2024.
MedlinePlus. Fever.
MedlinePlus. Fever.
Centers for Disease Control and Prevention. Symptoms of COVID-19.
Centers for Disease Control and Prevention. Testing for COVID-19.
Protsiv M, Ley C, Lankester J, et al. Decreasing human body temperature in the United States since the industrial revolution. Elife. 2020;9:e49555. Doi:10.7554/eLife.49555
Balli S, Shumway KR, Sharan S. Physiology, fever. In: StatPearls. StatPearls Publishing; 2024.
MedlinePlus. When your baby or infant has a fever.
American Academy of Family Physicians. Fever in infants and children.
Centers for Disease Control and Prevention. Definitions of signs, symptoms, and conditions of ill travelers.
MedlinePlus. Temperature measurement.
Thomas M, Bomar PA. Upper respiratory tract infection. In: StatPearls. StatPearls Publishing; 2024.
What Are Ticks And What Diseases Do They Spread?
Ticks are parasites, which means they live off a host. They feed on the blood of people and animals. Ticks might look like insects, but they're arachnids, such as spiders. There are many types of ticks, and they live in different parts of the U.S.
Ticks are related to spiders, so they have eight legs. They have flat, oval bodies that swell when they eat. They range in color from light brown to dark brown or brownish-red, depending on the species. All types are very small. The largest tick may swell to the size of an apple seed after it feeds, but many ticks are much smaller than that.
Ticks are flat before they feed. As they feed, they expand in size and become round. (Photo Credit: iStock/Getty Images)
Ticks can be hard or soft. Each type has a different type of body and life cycle.
Hard ticks (Ixodidae). This type has a hard outer shell called a scutum. Hard ticks come in 700 species. Their life cycle has four stages:
Hard ticks carry the germs that cause Lyme disease, Rocky Mountain spotted fever, and other diseases. Their bite doesn't hurt. It can take them hours, days, or weeks to feed.
Soft ticks (Argasidae). This type has a soft body and comes in 200 species. A soft tick's life cycle also has four phases:
Soft ticks can live for months to years. They mainly bite rodents such as rats and mice. Less often, they bite humans. Their bite is painless and they feed for just 15 to 30 minutes.
Only a small number of ticks bite and spread diseases to humans. How many ticks actually cause disease depends on the number of infected ticks in a certain area. For example, between 1% and 50% of ticks may be infected with the bacteria that cause Lyme disease. The actual risk of getting Lyme disease from a single tick bite is about 2%.
Ticks prefer to live in warm, humid climates. Many of them die when it's cold outside. Warming temperatures from climate change help ticks live longer, and allow them to move into more northern areas that were once too cold for them.
The most common types of ticks live in different parts of the U.S.:
When are ticks most active?
Ticks can be active at any time of the year, but they're most active in the spring and summer months, from April to September. That's when you're most likely to get a tick bite.
It's not just the outdoorsy types who get exposed to ticks. You may get bitten while playing, gardening, or doing yard work right outside your house, especially if you live in an area where there are a lot of ticks. Ticks can also hitch a ride on animals, such as pets, and get into your home that way.
It's common for a red bump to form in the area of the tick bite. This is a reaction to the tick's saliva. The bite may or may not itch.
Infections from a tick bite cause symptoms such as:
Rashes are another common symptom. Infections such as Rocky Mountain spotted fever and Lyme disease cause a rash that looks like:
Ticks spread disease by passing along bacteria, viruses, and parasites. Most of these illnesses cause typical flu-like symptoms, such as chills, fever, headache, and muscle aches.
Lyme disease
Lyme disease is a bacterial disease that spreads through the bite of infected blacklegged ticks in the upper Midwest, mid-Atlantic, and Northeast. The western blacklegged tick spreads Lyme disease along the Pacific Coast. In the U.S., Borrelia burgdorferi bacteria transmit Lyme disease. In other countries, other Borrelia species spread Lyme disease.
Soon after a tick bites, you may see the telltale bull's-eye rash. Lyme disease also causes flu-like symptoms, such as:
If you don't treat Lyme disease, it can get more serious and cause:
Doctors usually treat Lyme disease with antibiotics. The sooner you start taking these medicines, the better.
Other illnesses caused by ticks
Anaplasmosis. This bacterial illness spreads through the bite of the blacklegged tick and western blacklegged tick. In the first 5 days after infection, symptoms such as fever, chills, muscle, aches, and nausea are common. The illness can become serious if you don't treat it. Quick treatment with antibiotics usually clears up the infection.
Babesiosis.The blacklegged tick spreads this parasitic infection. The parasites infect red blood cells and cause symptoms such as fever, chills, headache, and body aches. Eventually, the parasites can destroy more red blood cells than your body can produce. Babesiosis can be life-threatening, especially if you're 50 or older, you had your spleen removed, or you have a weak immune system.
Hard tick relapsing fever (HTRF). This infection is caused by Borrelia miyamotoi bacteria. It's spread by blacklegged ticks in the upper midwestern, northeastern, and mid-Atlantic states, as well as in Pacific coastal states. Although its name indicates otherwise, research shows that people with HTRF usually only have one episode of fever. This comes along with flu-like symptoms such as chills, headache, fatigue, and achy muscles and joints. Taking antibiotics for about 2 weeks can clear up the infection.
Colorado tick fever.This rare viral disease spreads through bites from the Rocky Mountain wood tick. The tick lives in Rocky Mountain states at heights of 4,000 to 10,000 feet above sea level. If you get this infection, you may have a fever for several days, then feel fine for a while, and then have a fever again for a few more days. Chills, headache, and body aches are other symptoms. Most people who get Colorado tick fever have a mild illness that goes away within a few weeks.
Ehrlichiosis. This flu-like bacterial illness spreads through the bite of lone star and blacklegged ticks in the midwestern, south-central, and eastern U.S. Typical symptoms include fever, chills, headache, and muscle soreness. A few days later, some people get a cough, nausea, stomach pain, and a rash. A 5- to 7-day course of antibiotics should get rid of the infection.
Heartland virus. This is a viral illness that spreads in the eastern, southeastern, and south-central U.S. Lone star ticks spread the virus. Like other tick-borne illnesses, the Heartland virus causes flu-like symptoms such as tiredness, fever, nausea, and muscle or joint pain. It may also damage blood cells that help your body fight infections and stop you from bleeding.
Powassan virus.This virus used to be rare, but it has become more common in recent years. Backlegged ticks and groundhog ticks spread the virus in the Great Lakes and Northeast regions. Early symptoms include fever, headache, weakness, and vomiting. Sometimes, the virus can cause more serious problems such as memory loss, trouble speaking, and seizures.
Red meat allergy.This serious allergic condition happens after a bite from the lone star tick. Another name for the allergy is alpha-gal syndrome (AGS). The bite causes you to develop a meat allergy. When you're exposed to meat or other foods made from mammals (pork, lamb, venison), you may get symptoms such as hives, belly pain, shortness of breath, or even a severe, life-threatening reaction called anaphylaxis.
Rickettsia parkeri rickettsiosis. This is a bacterial infection spread by the Gulf Coast tick. After the bite, a dark scab forms on the skin, followed by a fever, muscle pain, headache, and rash. Some people have swollen glands. Antibiotics treat the infection.
Rocky Mountain spotted fever (RMSF). RMSF is a bacterial infection that spreads through the bite of the American dog tick, Rocky Mountain wood tick, and brown dog tick. Despite the name, it's most common in the southeastern and south-central U.S. Most people get a pink spotted rash on their hands, feet, arms, and legs. Other symptoms include a fever, headache, appetite loss, and stomach pain.
RMSF damages small blood vessels, which can cause swelling in the brain, heart, and lungs. Untreated, it can lead to amputation, hearing loss, and mental changes. Treating the bacteria with antibiotics can prevent complications, especially if you start the medicine within 5 days after your symptoms first appear.
Southern tick-associated rash illness (STARI). STARI is a disease with symptoms that are similar to those of Lyme disease, including a bull's-eye-like rash and joint pain. Bacteria cause Lyme disease, but experts don't know what type of germ causes STARI. The illness starts after a bite from the lone star tick. Other symptoms include tiredness, fever, headache, and muscle pain.
Tick-borne relapsing fever. This bacterial illness spreads through bites from the soft-bodied tick. People get it in mountainous areas from California to Ohio, usually after sleeping in rustic cabins infested with mice or rats. The illness causes a high fever, headache, muscle and joint aches, and chills. Fevers come in episodes with shaking chills and drenching sweats. This infection can be life-threatening without antibiotic treatment.
Tularemia.Also called "rabbit fever," tularemia is an infection with the bacteria Francisella tularensis. It spreads from the bite of a dog tick, wood tick, or lone star tick in many parts of the country. The most common symptoms are a high fever, swollen glands, sore throat, and an open, painful sore where you were bitten. Tularemia can be life-threatening, but it's treatable with antibiotics.
364D rickettsiosis. Also called Pacific Coast tick fever, it spreads along the coasts of California, Oregon, and Washington through the bite of the Pacific Coast tick. Rickettsia bacteria also cause this infection. 364D rickettsiosis causes fever, headache, muscle aches, and a dark scab in the bite area.
If you see a tick on your skin, try to remove it. Use fine-tipped tweezers to grab the tick as close as possible to your skin. Then, pull up with even pressure. Save the tick in a bag, in case you need to bring it to your doctor's office with you.
Contact a doctor if:
Ticks are parasites that feed on the blood of humans and animals and spread disease when they bite. Fever, chills, headache, and rash are common symptoms of an infection after a tick bite. If you see a tick on your skin, try to remove it with tweezers. See a doctor if you can't fully remove the tick, you have symptoms of a tick bite, or the bite looks infected.
What do ticks do?
Ticks are parasites that feed on the blood of humans and animals. They can spread disease when they bite.
What ticks carry Lyme disease?
Blacklegged ticks carry the bacteria that cause Lyme disease. These ticks live in the northeastern, mid-Atlantic, and north-central U.S.
How do you know if a tick has Lyme disease?
You can't tell if a tick has Lyme disease just by looking at it. But you'll know that you have the infection by symptoms such as a growing red bull's-eye rash, fever, chills, headache, and swollen glands.
Signs And Symptoms Of Influenza (Flu)
Influenza, commonly known as the flu, causes symptoms like a cough, fever, sore throat, and fatigue. The flu is a viral infection of the respiratory tract (the lungs, voice box, throat, nose, mouth, and airways). It's a highly contagious disease mostly caused by the viruses influenza A and B, both of which share similar symptoms.
The flu typically sets on rapidly. Not everyone with the flu will experience all, or even any, of the same symptoms. It's possible to have the flu and spread it to others without realizing you have it. The flu can cause more severe symptoms or even be fatal in adults older than 65, infants, or people with certain health conditions.
A characteristic sign of the flu is pain in the muscles and joints, or myalgia. These aches occur due to your body's immune reaction to flu viruses, which causes inflammation. A need to cough is another common sign of the flu. Your lungs form mucus to trap the virus. Coughing helps to rid your body of this infected mucus. Feeling very tired and needing more sleep is also a sign of infection. Your body expends more energy to fight off the disease. Other symptoms, such as coughing, can affect your sleep. Feeling feverish and experiencing chills are signs of your body fighting off an infection. You may have sweats and fluctuations in temperature, with body temperatures climbing to between 100 to 104 degrees. Another symptom often distinguishing the flu from a cold is headache, which is caused by cytokines. Your body releases these molecules as part of its natural immune reaction to the infection. A runny nose (rhinitis) or stuffy nose (nasal congestion) are common symptoms of respiratory infections like the flu. The soft tissues of your nasal passages can sometimes become inflamed due to infection. Not everyone who has the flu experiences a sore throat, but a dry, painful throat can sometimes be a sign of infection. It arises as the virus enters your body through soft tissues in the nasal passages and airways, causing irritation. The flu can spread from the respiratory tract to other parts of the body in some more severe cases—especially if the body is not able to fight off the infection. This response can lead to several symptoms, including an ear infection, pneumonia, and sinus infection. Ear Infection The flu virus can spread to the passages of the middle ear and cause inflammation and an ear infection, or otitis media. Ear pain and pressure, fever, and fussiness (in infants and children) are the most common signs. Pneumonia Pneumonia is a severe infection characterized by fluid or pus (a viscous fluid) build-up in the air sacs, or alveoli, of the lungs. It ranges in severity and can be fatal. Pneumonia causes symptoms like: Chest pain when coughing or breathing Chills Cough with or without mucus Fever Low oxygen levels in the blood (hypoxemia) Shortness of breath or difficulty breathing Sinus Infection Sinus infections (sinusitis) affect the pockets of air in your forehead, nasal passages, and cheeks. They are a moderate complication of the flu. This causes fluid build-up in these spaces, leading to symptoms like: Bad breath Cough Headache Pain or pressure in the face Post-nasal drip (mucus in the throat) Runny or stuffy nose Sore throat The flu can lead to life-threatening complications in rare, severe cases. Certain populations are at increased risk of these, including infants or children younger than 5, people older than 65, pregnant people, and those with health conditions like asthma, diabetes, or heart disease. Encephalitis The flu can cause a severe infection called encephalitis if it spreads to the tissues of the brain. This causes many symptoms, including: Difficulties understanding speech or speaking Double vision Flu-like symptoms Hallucinations Loss of consciousness Loss of touch sensation in parts of the body Memory loss Muscle weakness Partial paralysis of arms or limbs Seizures Multiple Organ Failure Multiple organ failure is one of the most common causes of death in people who experience flu complications. It's characterized by multiple organs, such as the lungs or kidneys, failing to operate. Symptoms of multiple organ failure include: Fatigue Headaches Itchiness Loss of appetite Memory or cognitive problems Pain and stiffness in the joints Sleep difficulties Swelling in the limbs Weight loss Muscle Infections Other rare complications of the flu affect the muscles. This can lead to myositis, or a cluster of conditions that cause muscle weakness, fatigue, and pain. Myositis can lead to rhabdomyolysis (rhabdo), or a potentially fatal breakdown of the muscles. Rhabdo can cause kidney or heart failure. Myocarditis Myocarditis occurs when the flu spreads to the muscles of the heart. This very serious condition causes symptoms like: Cardiac arrest (the heart stopping) Chest pain Fatigue and loss of energy Irregular heartbeat Persistent cough Swelling in the arms or legs Thick mucus, sometimes with spots of blood Wheezing Sepsis Sepsis is a blood infection that occurs due to an extreme immune reaction in your body. It's a dangerous medical emergency that requires immediate treatment. Signs and symptoms of sepsis include: Difficulty breathing or shortness of breath Disorientation or confusion Elevated heart rate Fever, chills, or shivers Rapid breathing Severe pain or discomfort Sweating or clammy skin Children, especially those younger than 2, are at a higher risk of the flu and its complications. About 9.3% of those younger than 18 develop the flu, which is more than twice the rate of adults older than 65. It's important to know the signs and symptoms of the flu in infants and children, such as: Body aches Diarrhea Earaches Fatigue Fever or chills Nausea or vomiting Runny nose Sore throat The flu is a highly contagious respiratory infection. It's spread from person to person through infectious droplets. An infected person can spread these droplets when they cough, sneeze, or talk near you. The droplets can land in your mouth or nose. It's less common, but you may pick up flu germs when you touch an infected surface and then touch your face. Any sign of severe illness warrants medical attention, which is critical given how severe the flu can be. Certain signs and symptoms in adults warrant emergency help, such as: Chronic pain or pressure in the chest Dizziness, lightheadedness, and confusion that doesn't go away A fever or cough that gets better but then returns and gets worse Lack of urination Seizures Severe muscle pain, weakness, or loss of balance Shortness of breath or breathing difficulties Worsening symptoms of other conditions, such as asthma Get medical attention right away if your child or infant has: Any fever in infants younger than 12 weeks or a fever above 104 degrees in children older than 3 months Bluish tint to the face or lips Chest or muscular pain No alertness when awake, a lack of interaction with others Rapid or difficult breathing Ribs retracting with every breath Seizure Signs of dehydration, such as dry mouth, lack of urination for eight hours or more, and no tears when crying Worsening fever or cough Worsening symptoms of other conditions The flu is a viral infection that primarily affects the respiratory system. Typical symptoms include cough, runny nose, fever, body aches, fatigue, and headache. It's rare, but complications may occur, ranging in severity from a sinus or ear infection to pneumonia, endocarditis, and encephalitis. It's important to seek out treatment, especially if your or your child's symptoms are severe.Thanks for your feedback!
Comments
Post a Comment