Disorders caused by pathogens, such as bacteria, fungi, viruses, or parasites are called infectious diseases. So many harmless organisms live in and on the human body. However, some are pathogens that cause illness and disease.
Infectious diseases are widespread disorders across the world. Certain infectious diseases infect people more than others do. For example, in the United States, nearly 20% of people suffer from the influenza virus every year, which is a viral infectious disease.
What are Signs and Symptoms of Infectious Disease?
Symptoms and signs are different depending upon the organism that causes infection 1. However, some signs and symptoms occur with almost all infectious diseases.
Common symptoms of infectious diseases include 1,2:
- Diarrhea or GI upset
- Muscle aches
Causes of Infectious diseases
Pathogens entering the body cause infectious diseases by using the host’s body to survive and replicate3. When the pathogen invades the body, it damages the immune system and causes fatigue and fever before shifting to a new host. Transmission occurs when the pathogen is passed from one host to another2.
Types of Infections
There are a variety of infections caused by different pathogens. The most common types are:
- Bacterial infections
- Fungal infections
- Viral infections
- Parasitic infections
Viruses are covered by a coating of protein and are made up of a piece of genetic code. This code is ribonucleic acid (RNA) or deoxyribonucleic acid (DNA). After entering into the body, viruses invade host cells. Next, they use the components of the host cells to replicate and produce more viruses.
Viruses cause common infectious diseases such as influenza, cold, and warts. In certain cases, they may lead to severe illnesses such as chickenpox, polio, Ebola, HIV, AIDS, and COVID-19.
Bacteria are tiny single-cell organisms. Not all bacteria cause infections, some healthy forms of bacteria line the gut and other areas in the body like the nose, mouth, skin, and vagina4. Only pathogenic bacteria are harmful.
Examples of bacterial infections include tuberculosis, whooping cough, syphilis, pneumococcal pneumonia, cholera, botulism, tetanus, anthrax, and bacterial meningitis.
Millions of different fungal species are found on the earth. Not all, but nearly three hundred may cause illness. Fungi are present everywhere in the atmosphere, including outdoors, indoors, and on the human body. When they’re overgrown, they cause infections. Fungi cells have a nucleus and other components covered by a thick wall of protein. With these barriers, they’re harder to kill by antibiotics.
Infections caused by fungi include athlete’s foot, thrush, ringworm, aspergillosis, histoplasmosis, fungal meningitis, and cryptococcus infection.
Parasites live in or on the host body and get their food and other nutrients from the host and in return harm them. There are three types of parasites that may lead to illness in the human body:
- Protozoa: small, unicellular organisms
- Helminths: larger, worm-like organisms
- Ectoparasites: organisms such as fleas, lice, and ticks.
Parasites may cause infections like tapeworm infection, roundworm infection, scabies, river blindness, malaria, and toxoplasmosis.
Transmission of infectious diseases
Certain infectious diseases are contagious. Few are spread by insects or other animals. Consuming contaminated water or food or being exposed to bacterial organisms in the environment can also cause illness.
Everybody is liable to suffer from infectious diseases. Those with a low immune system have a greater risk for certain types of infections. People at higher risk are1:
- Those with suppressed immune systems, for instance, those under cancer treatment, pregnant, or those having an organ transplant recently
- Those traveling to risky areas where they can be exposed toparasites that carry malaria, Zika viruses, and dengue virus
- People who have not been vaccinated against common infectious diseases
- Healthcare staff
Preventive measures that can be taken to reduce the risk of infectious diseases include 1:
- Wash hands thoroughly and frequently with soap and water.
- Ensure covering of nose and mouth while sneezing or coughing.
- Do not use contaminated water for drinking or swimming in any circumstances.
- Disinfect high touch surfaces in the home and workplaces thoroughly and frequently.
- Avoid sharing personal items like combs, razors, or toothbrushes.
- Avoid contact with sick people.
- Avoid eating or drinking food and beverages prepared by sick people.
- Do not share drinking or dining utensils.
Treating Infectious Disease
Common antibiotics treat most bacterial infections1. However, some types of bacteria are resistant to the usual antibiotics and require a different approach. Antiviral medications can treat some viruses, but it must be administered early on in the infection. There are also antiparasitics and antifungals, depending on the causative pathogen type.
Infections of a mild nature may be cured by rest, hydration and supportive home remedies. But life-threatening infections need proper health care and hospitalization. Regardless of the type of infectious disease, seek medical care immediately for guidance.
- Mayo Clinic. Infectious diseases. 2021.
- Cleveland clinic. Infectious diseases. 2018.
- Healthline. What you need to know about pathogens and the spread of disease. 2019.
- Mohajeri, M. H., Brummer, R. J. M., Rastall, R. A., Weersma, R. K., Harmsen, H. J. M., Faas, M., & Eggersdorfer, M. (2018, May). The role of the microbiome for human health: From basic science to clinical applications. European journal of nutrition. Retrieved August 30, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5962619/