A list of the more common and well-known diseases associated with infectious pathogens is provided and is not intended to be a complete listing.

Other causes or associations of disease are: a compromised immune system, environmental toxins, radiation exposure, diet and lifestyle choices, stress, and genetics. Diseases may also be multifactorial, requiring multiple factors to induce disease. For example: in a murine model, Crohn's disease can be precipitated by a norovirus, but only when both a specific gene variant is present and a certain toxin has damaged the gut.

The U.S. Centers for Disease Control and Prevention (CDC) publishes a journal "Emerging Infectious Diseases" that identifies the following factors contributing to disease emergence:

- Microbial adaption; e.g. genetic drift and genetic shift in Influenza A

- Changing human susceptibility; e.g. mass immunocompromisation with HIV/AIDS

- Climate and weather; e.g. diseases with zoonotic vectors such as West Nile Disease (transmitted by mosquitoes) are moving further from the tropics as the climate warms

- Change in human demographics and trade; e.g. rapid travel enabled SARS to rapidly propagate around the globe

- Economic development; e.g. use of antibiotics to increase meat yield of farmed cows leads to antibiotic resistance

- Breakdown of public health; e.g. the current situation in Zimbabwe

- Poverty and social inequality; e.g. tuberculosis is primarily a problem in low-income areas

- War and famine

- Bioterrorism; e.g. 2001 Anthrax attacks

- Dam and irrigation system construction; e.g. malaria and other mosquito borne diseases

Infectious diseases are sometimes called contagious disease when they are easily transmitted by contact with an ill person or their secretions (e.g., influenza). Thus, a contagious disease is a subset of infectious disease that is especially infective or easily transmitted. Other types of infectious/transmissible/communicable diseases with more specialized routes of infection, such as vector transmission or sexual transmission, are usually not regarded as "contagious", and often do not require medical isolation (sometimes loosely called quarantine) of victims. However, this specialized connotation of the word "contagious" and "contagious disease" (easy transmissibility) is not always respected in popular use.

Infectious diseases are commonly transmitted from person to person through direct contact. The types of contact are through person to person and droplet spread. Indirect contact such as airborne transmission, contaminated objects, food and drinking water, animal person contact, animal reservoirs, insect bites, and environmental reservoirs are another way infectious diseases are transmitted,

For infecting organisms to survive and repeat the infection cycle in other hosts, they (or their progeny) must leave an existing reservoir and cause infection elsewhere. Infection transmission can take place via many potential routes:

- Droplet contact, also known as the "respiratory route", and the resultant infection can be termed airborne disease. If an infected person coughs or sneezes on another person the microorganisms, suspended in warm, moist droplets, may enter the body through the nose, mouth or eye surfaces.

- Fecal-oral transmission, wherein foodstuffs or water become contaminated (by people not washing their hands before preparing food, or untreated sewage being released into a drinking water supply) and the people who eat and drink them become infected. Common fecal-oral transmitted pathogens include "Vibrio cholerae", "Giardia" species, rotaviruses, "Entameba histolytica", "Escherichia coli", and tape worms. Most of these pathogens cause gastroenteritis.

- Sexual transmission, with the resulting disease being called sexually transmitted disease

- Oral transmission, Diseases that are transmitted primarily by oral means may be caught through direct oral contact such as kissing, or by indirect contact such as by sharing a drinking glass or a cigarette.

- Transmission by direct contact, Some diseases that are transmissible by direct contact include athlete's foot, impetigo and warts

- Vehicle Transmission, transmission by an inanimate reservoir (food, water, soil).

- Vertical transmission, directly from the mother to an embryo, fetus or baby during pregnancy or childbirth. It can occur when the mother gets an infection as an intercurrent disease in pregnancy.

- Iatrogenic transmission, due to medical procedures such as injection or transplantation of infected material.

- Vector-borne transmission, transmitted by a vector, which is an organism that does not cause disease itself but that transmits infection by conveying pathogens from one host to another.

The relationship between "virulence versus transmissibility" is complex; if a disease is rapidly fatal, the host may die before the microbe can be passed along to another host.

An emerging infectious disease (EID) is an infectious disease whose incidence has increased in the past 20 years and could increase in the near future. Emerging infections account for at least 12% of all human pathogens. EIDs are caused by newly identified species or strains (e.g. Severe acute respiratory syndrome, HIV/AIDS) that may have evolved from a known infection (e.g. influenza) or spread to a new population (e.g. West Nile fever) or to an area undergoing ecologic transformation (e.g. Lyme disease), or be "reemerging" infections, like drug resistant tuberculosis. Nosocomial (hospital-acquired) infections, such as methicillin-resistant Staphylococcus aureus are emerging in hospitals, and extremely problematic in that they are resistant to many antibiotics. Of growing concern are adverse synergistic interactions between emerging diseases and other infectious and non-infectious conditions leading to the development of novel syndemics. Many emerging diseases are zoonotic - an animal reservoir incubates the organism, with only occasional transmission into human populations.

Outbreaks of zoonoses have been traced to human interaction with and exposure to animals at fairs, petting zoos, and other settings. In 2005, the Centers for Disease Control and Prevention (CDC) issued an updated list of recommendations for preventing zoonosis transmission in public settings. The recommendations, developed in conjunction with the National Association of State Public Health Veterinarians, include educational responsibilities of venue operators, limiting public and animal contact, and animal care and management.

Contact with farm animals can lead to disease in farmers or others that come into contact with infected animals. Glanders primarily affects those who work closely with horses and donkeys. Close contact with cattle can lead to cutaneous anthrax infection, whereas inhalation anthrax infection is more common for workers in slaughterhouses, tanneries and wool mills. Close contact with sheep who have recently given birth can lead to clamydiosis, or enzootic abortion, in pregnant women, as well as an increased risk of Q fever, toxoplasmosis, and listeriosis in pregnant or the otherwise immunocompromised. Echinococcosis is caused by a tapeworm which can be spread from infected sheep by food or water contaminated with feces or wool. Bird flu is common in chickens. While rare in humans, the main public health worry is that a strain of bird flu will recombine with a human flu virus and cause a pandemic like the 1918 Spanish flu. In 2017, free range chickens in the UK were temporarily ordered to remain inside due to the threat of bird flu. Cattle are an important reservoir of cryptosporidiosis and mainly affects the immunocompromised.

Equine infectious anemia or equine infectious anaemia (EIA), also known by horsemen as swamp fever, is a horse disease caused by a retrovirus and transmitted by bloodsucking insects. The virus ("EIAV") is endemic in the Americas, parts of Europe, the Middle and Far East, Russia, and South Africa. The virus is a lentivirus, like human immunodeficiency virus (HIV). Like HIV, EIA can be transmitted through blood, milk, and body secretions.

Transmission is primarily through biting flies, such as the horse-fly and deer-fly. The virus survives up to 4 hours in the vector (epidemiology). Contaminated surgical equipment and recycled needles and syringes, and bits can transmit the disease. Mares can transmit the disease to their foals via the placenta.

The risk of transmitting the disease is greatest when an infected horse is ill, as the blood levels of the virus are then highest.

A vaccine is available, called "Chinese Live Attenuated EIA vaccine", developed in China and widely used there since 1983. Another attenuated live virus vaccine is in development in the United States.

Reuse of syringes and needles is a risk factor for transfer of the disease. Currently in the United States, all horses that test positive must be reported to federal authorities by the testing laboratory. EIA-positive horses are infected for life. Options for the horse include sending the horse to a recognized research facility, branding the horse and quarantining it at least 200 yards from other horses for the rest of its life, and euthanizing the horse. Very few quarantine facilities exist, which usually leads to the option of euthanizing the horse. The Florida Research Institute for Equine Nurturing, Development and Safety (a.k.a. F.R.I.E.N.D.S.) is one of the largest such quarantine facilities and is located in south Florida.

The horse industry and the veterinary industry strongly suggest that the risks posed by infected horses, even if they are not showing any clinical signs, are enough of a reason to impose such stringent rules. The precise impacts of the disease on the horse industry are unknown.

Porcine circoviral disease (PCVD) and Porcine circovirus associated disease (PCVAD), is a disease seen in domestic pigs. This disease causes illness in piglets, with clinical signs including progressive loss of body condition, visibly enlarged lymph nodes, difficulty in breathing, and sometimes diarrhea, pale skin, and jaundice. PCVD is very damaging to the pig-producing industry and has been reported worldwide. PCVD is caused by porcine circovirus type 2 (PCV-2).

The North American industry endorses "PCVAD" and European use "PCVD" to describe this disease.

Postweaning multisystemic wasting syndrome ("PMWS") is the classic PCVD entity, caused by PCV-2. PCV-2 has a near universal distribution – present in most pig herds. In contrast, PMWS is more sporadic in its distribution. Experimental induction of PMWS has not been achieved by PCV-2 infection alone, using infectious DNA clones of the virus or a pure form of PCV-2 derived from infectious DNA clones. Therefore, it is assumed that PMWS is a multifactorial disease. PCV-2 is necessary but not sufficient for the development of PMWS. However, viral infection by itself tends to cause only mild disease, and co-factors such as other infections or immunostimulation seem necessary for development of severe disease.[1] For example, concurrent infection with porcine parvovirus or PRRS virus, or immunostimulation lead to increased replication of PCV-2 and more severe disease in PCV-2-infected pigs. There is no significant correlation of the disease with virus sequence variation with affected and control pigs.

Infectious pancreatic necrosis (IPN) is a severe viral disease of salmonid fish. It is caused by infectious pancreatic necrosis virus, which is a member of the Birnaviridae family. This disease mainly affects young salmonids, such as trout or salmon, of less than six months, although adult fish may carry the virus without showing symptoms. Resistance to infection develops more rapidly in warmer water. It is highly contagious and found worldwide, but some regions have managed to eradicate or greatly reduce the incidence of disease. The disease is normally spread horizontally via infected water, but spread also occurs vertically. It is not a zoonosis.

Ultraviolet (UV) radiation is implicated in cattle with no pigmentation around the eyelids and cattle with prominently placed eyes. Exudate from the sun-burnt skin around the eyes can contain bacteria and attracts flies. UV light also directly damages the corneal epithelium, leading to a breakdown in host innate immunity.

Dust, dried-up plants, tall vegetation, and oversized or incorrectly placed ear tags may cause mechanical damage to the eye and facilitate bacterial colonization.

The disease may be complicated by concurrent infection with viruses such as infectious bovine rhinotracheitis virus (bovine herpesvirus 1) or adenovirus, bacteria such as "Mycoplasma boviculi" or "Listeria monocytogenes", or infestation by "Thelazia", a nematode.

Vitamin A deficiency is also implicated.

IBK is most prevalent in summer and early autumn.

A recent Meat and Livestock Australia report "estimates that the disease costs Australian beef producers AU$23.5 million annually in lost production and treatment costs".

Any age may be affected although it is most common in children aged five to fifteen years. By the time adulthood is reached about half the population will have become immune following infection at some time in their past. Outbreaks can arise especially in nursery schools, preschools, and elementary schools. Infection is an occupational risk for school and day-care personnel. There is no vaccine available for human parvovirus B19, though attempts have been made to develop one.

Feline infectious anemia (FIA) is an infectious disease found in felines, causing anemia and other symptoms. The disease is caused by a variety of infectious agents, most commonly "Mycoplasma haemofelis" (which used to be called "Haemobartonella"). "Haemobartonella" and "Eperythrozoon" species were reclassified as mycoplasmas. Coinfection often occurs with other infectious agents, including: feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), "Ehrlichia" species, "Anaplasma phagocytophilum", and Candidatus "Mycoplasma haemominutum".

Caseous lymphadenitis (CLA) is an infectious disease caused by the bacterium "Corynebacterium pseudotuberculosis" found mostly in goats and sheep that at present has no cure. It manifests itself predominantly in the form of large, pus-filled cysts on the neck, sides and udders of goats and sheep. The disease is spread mostly from an animal coming in contact with pus from a burst cyst on an infected animal, but the disease is highly contagious and is thought to also be spread by coughing or even by flies. Studies have found CL incidence in commercial goat herds as high as 30%.

White plague is a suite of coral diseases of which three types have been identified, initially in the Florida Keys. They are infectious diseases but it has proved difficult to identify the pathogens involved. White plague type II may be caused by the gram negative bacterium "Aurantimonas coralicida" in the order Rhizobiales but other bacteria have also been associated with diseased corals and viruses may also be implicated.

"Moraxella bovis" is a Gram-negative rod-shaped aerobe. This bacterium is an obligate intracellular parasite of the mucous membranes, and can usually be isolated from the respiratory tract, vagina, and conjunctiva of healthy animals. Transmission of IBK is through direct contact with mucous membranes and their secretions and indirect contact where flies act as a mechanical vector. Asymptomatic carrier animals can also be source of infection.

Currently, no treatment is available.

Good husbandry measures, such as high water quality, low stocking density, and no mixing of batches, help to reduce disease incidence. To eradicate the disease, very strict protocol with regards to movement, water sources and stock replacement must be in place – and still it is difficult to achieve and comes at a high economic cost.

Symptoms of infectious mononucleosis are fever, sore throat, and swollen lymph glands. Sometimes, a swollen spleen or liver involvement may develop. Heart problems or involvement of the central nervous system occurs only rarely, and infectious mononucleosis is almost never fatal. There are no known associations between active EBV infection and problems during pregnancy, such as miscarriages or birth defects. Although the symptoms of infectious mononucleosis usually resolve in 1 or 2 months, EBV remains dormant or latent in a few cells in the throat and blood for the rest of the person's life. Periodically, the virus can reactivate and is commonly found in the saliva of infected persons. Reactivated and post-latent virus may pass the placental barrier in (also seropositive) pregnant women via macrophages and therefore can infect the fetus. Also re-infection of prior seropositive individuals may occur. In contrast, reactivation in adults usually occurs without symptoms of illness.

EBV also establishes a lifelong dormant infection in some cells of the body's immune system. A late event in a very few carriers of this virus is the emergence of Burkitt's lymphoma and nasopharyngeal carcinoma, two rare cancers. EBV appears to play an important role in these malignancies, but is probably not the sole cause of disease.

Most individuals exposed to people with infectious mononucleosis have previously been infected with EBV and are not at risk for infectious mononucleosis. In addition, transmission of EBV requires intimate contact with the saliva (found in the mouth) of an infected person. Transmission of this virus through the air or blood does not normally occur. The incubation period, or the time from infection to appearance of symptoms, ranges from 4 to 6 weeks. Persons with infectious mononucleosis may be able to spread the infection to others for a period of weeks. However, no special precautions or isolation procedures are recommended, since the virus is also found frequently in the saliva of healthy people. In fact, many healthy people can carry and spread the virus intermittently for life. These people are usually the primary reservoir for person-to-person transmission. For this reason, transmission of the virus is almost impossible to prevent.

The clinical diagnosis of infectious mononucleosis is suggested on the basis of the symptoms of fever, sore throat, swollen lymph glands, and the age of the patient. Usually, laboratory tests are needed for confirmation. Serologic results for persons with infectious mononucleosis include an elevated white blood cell count, an increased percentage of certain atypical white blood cells, and a positive reaction to a "mono spot" test.

Spondweni fever is an infectious disease caused by the Spondweni virus. It is characterized by a fever, chills, nausea, headaches, malaise and epistaxis. Transmitted by mosquitoes, it is found in sub-Saharan Africa and Papua New Guinea.

Every infectious agent is different, but in general, slow viruses:

Additionally, the immune system seems to plays a limited role, or no role, in protection from these slow viruses. This may be in part because the host has acclimated to the virus, or more likely because the host must be immunocompromised in order for many of these slow virus infections to emerge, so the immune system is at a disadvantage from the start.

An airborne disease can be caused by exposure to a source: an infected patient or animal, by being transferred from the infected person or animal’s mouth, nose, cut, or needle puncture. People receive the disease through a portal of entry: mouth, nose, cut, or needle puncture.

A contagious disease is a subset category of transmissible diseases, which are transmitted to other persons, either by physical contact with the person suffering the disease, or by casual contact with their secretions or objects touched by them or airborne route among other routes.

Non-contagious infections, by contrast, usually require a special mode of transmission between persons or hosts. These include need for intermediate vector species (mosquitoes that carry malaria) or by non-casual transfer of bodily fluid (such as transfusions, needle sharing or sexual contact).

The boundary between contagious and non-contagious infectious diseases is not perfectly drawn, as illustrated classically by tuberculosis, which is clearly transmissible from person to person, but was not classically considered a contagious disease. In the present day, most sexually transmitted diseases are considered contagious, but only some of them are subject to medical isolation.