Infectious Diseases – Symptoms and Causes
Overview
Infections can easily pass from one person to another through simple contact. When someone who is sick touches, kisses, coughs, or sneezes near you, they can pass germs directly to you. These germs might be bacteria, viruses, fungi, or parasites.
Some people can spread disease without showing any symptoms themselves. They are carriers who look healthy but can make others sick. Meanwhile, body fluids exchanged during sexual contact are another way infections spread between people.
Mothers can pass infections to their babies before birth through the placenta. Germs can also be transferred during childbirth or through breast milk after the baby is born.
Causes
Environmental Transmission
Germs don’t always need direct contact to spread. They can survive on everyday objects like doorknobs, phones, tables, and faucet handles.
When you touch these surfaces after a sick person has left germs behind, you can pick up the infection.
If you then touch your face before washing your hands, the germs can enter your body through your eyes, nose, or mouth.
Common surfaces where germs linger:
- Door handles
- Cell phones
- Computer keyboards
- Shared towels
- Light switches
Bug Bites and Infections
Some diseases reach humans through insect bites. Scientists call these insects “vectors” because they carry disease from one host to another.
Common disease-carrying insects:
- Mosquitoes (malaria, West Nile virus)
- Ticks (Lyme disease)
- Fleas
- Lice
These tiny creatures bite an infected animal or person, pick up the germs, and then inject them into the next person they bite.
Contaminated Food and Drink
Eating or drinking items containing harmful germs can make many people sick at once. This is why food poisoning often affects groups who ate at the same restaurant or event.
Bacteria like E. coli can live in undercooked meat, unpasteurized milk, or unwashed produce. When food isn’t handled properly during preparation, storage, or cooking, dangerous organisms can multiply and cause illness when eaten.
High-risk foods:
| Food Type | Potential Germs |
|---|---|
| Raw meat | Salmonella, E. coli |
| Unpasteurized dairy | Listeria, Brucella |
| Raw seafood | Vibrio, hepatitis A |
| Unwashed produce | E. coli, parasites |
Symptoms
Common signs of infection include:
- Fever
- Diarrhea
- Fatigue
- Muscle aches
- Coughing
These symptoms vary depending on the specific disease affecting the person. Each infection creates its own pattern of signs.
When You Should See a Doctor
Contact a healthcare provider right away if you experience any of these issues:
- Animal bites
- Breathing difficulties
- Cough lasting longer than 7 days
- Strong headache with fever
- Unusual rash or swelling
- Fever that won’t go away
- Sudden changes in vision
These symptoms can indicate serious health problems that need professional evaluation. Don’t delay seeking medical help when these warning signs appear.
Risk Factors
Certain conditions can make you more vulnerable to catching infectious diseases:
- Weakened immune system from medications like steroids or anti-rejection drugs for organ transplants
- HIV or AIDS infection
- Certain cancers that affect immune function
Other factors that increase infection risk include:
- Having implanted medical devices
- Poor nutrition
- Being very young or elderly
When your body’s natural defenses are compromised, germs have an easier time invading and causing illness.
Complications
Most infections lead to minor problems. However, some diseases like pneumonia, AIDS, and meningitis can threaten lives.
Certain infections increase cancer risk over time. For example, human papillomavirus raises cervical cancer risk. Meanwhile, Helicobacter pylori bacteria is associated with stomach cancer and peptic ulcers. Also, hepatitis B and C viruses are connected to liver cancer development.
Some infections can hide in the body and reappear later. For instance, a person who had chickenpox as a child might develop shingles years or even decades later when the virus reactivates.
Ways to Stay Healthy
Hand washing is one of the best ways to stop infections. Wash before and after cooking, before meals, and after using the bathroom. Also, avoid touching your face with unwashed hands since germs enter the body this way.
Keep your vaccinations current. Vaccines help protect you and your children from many serious illnesses.
Stay home when sick. If you or your child has vomiting, diarrhea, or fever, don’t go to work or school.
Proper food handling prevents many infections. Wash produce well, and keep raw foods separate from ready-to-eat items to avoid contamination.
Keep kitchen surfaces clean when cooking. Use a food thermometer to ensure proper cooking temperatures:
- Ground meat: 160°F (71°C)
- Poultry: 165°F (74°C)
- Other meats: 145°F (63°C)
Put leftovers in the refrigerator quickly. Don’t leave cooked foods at room temperature for long periods.
Practice safe sex by using condoms, especially if you or your partner has had sexually transmitted infections or high-risk behaviors.
When traveling abroad, check with your doctor about needed vaccines like yellow fever, cholera, hepatitis A or B, or typhoid fever.
More Health Tips
- Keep your living space clean. Make sure to pay extra attention to bathrooms and kitchens.
- Stay active with regular exercise. This will help boost your immune system.
- Make sure to get enough sleep. Most adults need 7-8 hours per night.
- Stay hydrated by drinking plenty of water throughout the day.
- Consider using hand sanitizer when soap and water aren’t available.
