Infections and Diseases

Infections are the invasion and multiplication of an organism’s body tissues by pathogenic agents like bacteria and viruses.

  • Infection is often used as a synonym for disease even though the two are quite different. Infection is the entry of an agent into the body while a disease is the changes occurring in the body as a result of that entry.
  • All infections are caused by infectious agents which can be either bacteria, virus, fungi, or a parasite.
  • Infection is communicable that transmits due to the transmission of the infectious agent by different modes of transmission.
  • Depending on the infectious agent, infections are of four types; viral infection, bacterial infection, fungal infection, and parasitic infection.
  • Infections might not result in particular symptoms like diseases, as most infections tend to be subclinical.
  • Infections might be localized where the infectious agent only infects a particular organ or tissue or can be systemic where the agent reaches different parts of the body via blood or lymph to infect different organs and tissues.
  • Microorganisms that belong to the normal flora of an organism are not considered infectious agents unless they reach the sterile parts of the body to initiate some form of infection.
  • The pathophysiology of infections differs from one agent to another, but the general pattern of infections flows a similar trajectory; entry, colonization, disease, and transmission.
  • Symptoms of infections are also different depending on the type of infection, but some common symptoms include fever, chills, body aches, coughing, and sneezing.
  • The diagnosis of infection is based on the identification of the infectious agent via different diagnostic processes.
  • Some infections might show symptoms that allow for the symptomatic diagnosis, yet it usually needs further confirmation.
  • Infections are directly dependent on the infectious agent and the immune response of the host against the said agent.

Diseases are abnormal medical conditions that negatively affect the structure or function of an organism, other than immediate external injuries.

  • There are two types of diseases, viz., communicable and non-communicable diseases.
  • Infectious or communicable diseases are caused by viruses, pathogens, and other parasites that affect the host and can transmit from person to person. In contrast, non-communicable diseases might occur due to exposure to radiation, genetic inheritance, and an unhealthy lifestyle.
  • Whenever a disease-causing virus or pathogen enters the body of a host, the body shows two responses to it; clinical and immunologic. 
  • The white blood cells, mainly known for the defense against external microorganisms, attack such antigens which may result in different reactions such as fever, cold, headache, sweating, change in the rate of heartbeat, etc.
  • Plants also suffer from several diseases which are primarily caused by non-native viral, bacterial, and fungal pathogens. 
  • A few of such diseases that cause significant damage are a chestnut blight, butternut canker, Dogwood anthracnose, Elm yellows, etc.
  • Similarly, diseases are observed in plants and animals. Various bacteria and viruses cause diseases such as Anthrax, Black-quarter, Bluetongue, Pox. Rabies, etc. infect dogs, wolves, and foxes. 
  • The most effective and efficient way to prevent diseases is sanitation, proper nutrition, exercise, and self-care. 
  • Moreover, different forms of vaccines have been developed to prevent severe diseases like Cholera, Hepatitis A, Hepatitis E, Rabies, Yellow fever.
  • Although diseases can be fatal to humans, animals, and plants, their scientific study is useful in other fields of study.
  • Knowledge regarding disease-causing pathogens and bacteria helps microbiologists understand the nature and characteristics of various microorganisms.
  • Scientific diagnosis of parasites encourages people to take preventive measures for themselves and other animals.
  • Diseases have been an essential topic of research and findings in food microbiology as food and water are primary modes of transmission of many infectious diseases.