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

For a person or companion animal to acquire a tick-borne disease requires that that individual gets bitten by a tick and that that tick feeds for a sufficient period of time. The feeding time required to transmit pathogens differs for different ticks and different pathogens. Transmission of the bacterium that causes Lyme disease is well understood to require a substantial feeding period.

For an individual to acquire infection, the feeding tick must also be infected. Not all ticks are infected. In most places in the US, 30-50% of deer ticks will be infected with "Borrelia burgdorferi" (the agent of Lyme disease). Other pathogens are much more rare. Ticks can be tested for infection using a highly specific and sensitive qPCR procedure. Several commercial labs provide this service to individuals for a fee. The Laboratory of Medical Zoology (LMZ), a nonprofit lab at the University of Massachusetts, provides a comprehensive TickReport for a variety of human pathogens and makes the data available to the public. Those wishing to know the incidence of tick-borne diseases in their town or state can search the LMZ surveillance database.

Ticks tend to be more active during warmer months, though this varies by geographic region and climate. Areas with woods, bushes, high grass, or leaf litter are likely to have more ticks. Those bitten commonly experience symptoms such as body aches, fever, fatigue, joint pain, or rashes. People can limit their exposure to tick bites by wearing light-colored clothing (including pants and long sleeves), using insect repellent with 20%–30% DEET, tucking their pants legs into their socks, checking for ticks frequently, and washing and drying their clothing (in a hot dryer).

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.

Infectious pathogen-associated diseases include many of the most common and costly chronic illnesses. The treatment of chronic diseases accounts for 75% of all US healthcare costs (amounting to $1.7 trillion in 2009).

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.

Preventing Valley fever is challenging because it is difficult to avoid breathing in the fungus should it be present, however, the public health effect of the disease is essential to understand in areas where the fungus is endemic. Enhancing surveillance of Coccidiodomycosis is key to preparedness in the medical field in addition to improving diagnostics for early infections. Currently there are no completely effective preventive measures available for people who live or travel through Valley Fever -endemic areas. Recommended preventive measures include avoiding airborne dust or dirt, but this does not guarantee protection against infection. People in certain occupations may be advised to wear face masks. The use of air filtration indoors is also helpful, in addition to keeping skin injuries clean and covered to avoid skin infection.

In 1998-2011, there were 111,117 cases of coccidioidomycosis in the U.S. that were logged into the National Notifiable Diseases Surveillance System (NNDSS). Since many U.S. states do not require reporting of coccidioidomycosis, the actual numbers can be higher. The United States' Centers for Disease Control and Prevention (CDC) called the disease a "silent epidemic" and acknowledged that there is no proven anticoccidioidal vaccine available. Studies done in the past show that the cost benefit of a vaccine is most notable among infants, teens, and immigrant adults, with negative cost-benefit results among older age groups.

Raising both surveillance and awareness of the disease while medical researchers are developing a human vaccine can positively contribute towards prevention efforts. Research demonstrates that patients from endemic areas who are aware of the disease are most likely to request diagnostic testing for coccidioidomycosis. Presently, Meridian Bioscience manufactures the so-called "EIA test" to diagnose the Valley fever, which however is known for producing a fair quantity of false positives. Currently, recommended prevention measures can include type-of-exposure-based respirator protection for persons engaged in agriculture, construction and others working outdoors in endemic areas. Dust control measures such as planting grass and wetting the soil, and also limiting exposure to dust storms are advisable for residential areas in endemic regions.

The term waterborne disease is reserved largely for infections that predominantly are transmitted through contact with or consumption of infected water. Trivially, many infections may be transmitted by microbes or parasites that accidentally, possibly as a result of exceptional circumstances, have entered the water, but the fact that there might be an occasional freak infection need not mean that it is useful to categorise the resulting disease as "waterborne". Nor is it common practice to refer to diseases such as malaria as "waterborne" just because mosquitoes have aquatic phases in their life cycles, or because treating the water they inhabit happens to be an effective strategy in control of the mosquitoes that are the vectors.

Microorganisms causing diseases that characteristically are waterborne prominently include protozoa and bacteria, many of which are intestinal parasites, or invade the tissues or circulatory system through walls of the digestive tract. Various other waterborne diseases are caused by viruses. (In spite of philosophical difficulties associated with defining viruses as "organisms", it is practical and convenient to regard them as microorganisms in this connection.)

Yet other important classes of water-borne diseases are caused by metazoan parasites. Typical examples include certain Nematoda, that is to say "roundworms". As an example of water-borne Nematode infections, one important waterborne nematodal disease is Dracunculiasis. It is acquired by swallowing water in which certain copepoda occur that act as vectors for the Nematoda. Anyone swallowing a copepod that happens to be infected with Nematode larvae in the genus Dracunculus, becomes liable to infection. The larvae cause guinea worm disease.

Another class of waterborne metazoan pathogens are certain members of the Schistosomatidae, a family of blood flukes. They usually infect victims that make skin contact with the water. Blood flukes are pathogens that cause Schistosomiasis of various forms, more or less seriously affecting hundreds of millions of people worldwide.

Long before modern studies had established the germ theory of disease, or any advanced understanding of the nature of water as a vehicle for transmitting disease, traditional beliefs had cautioned against the consumption of water, rather favouring processed beverages such as beer, wine and tea. For example, in the camel caravans that crossed Central Asia along the Silk Road, the explorer Owen Lattimore noted, "The reason we drank so much tea was because of the bad water. Water alone, unboiled, is never drunk. There is a superstition that it causes blisters on the feet."

The list below shows the main diseases that can be passed via the fecal–oral route. They are grouped by the type of pathogen involved in disease transmission.

There are several populations that have a higher risk for contracting coccidioidomycosis and developing the advanced disseminated version of the disease. Populations with exposure to the airborne arthroconidia working in agriculture and construction have a higher risk. Outbreaks have also been linked to earthquakes, windstorms and military training exercises where the ground is disturbed. Historically an infection is more likely to occur in males than females, although this could be attributed to occupation rather than gender specific. Women who are pregnant and immediately postpartum are at a high risk of infection and dissemination. There is also an association between stage of pregnancy and severity of the disease, with third trimester women being more likely to develop dissemination. Presumably this is related to highly elevated hormonal levels, which stimulate growth and maturation of spherules and subsequent release of endospores. Certain ethnic populations are more susceptible to disseminated coccioidomycosis. The risk of dissemination is 175 times greater in Filipinos and 10 times greater in African Americans than non-Hispanic whites. Individuals with a weakened immune system are also more susceptible to the disease. In particular, individuals with HIV and diseases that impair T-cell function. Individuals with pre-existing conditions such as diabetes are also at a higher risk. Age also affects the severity of the disease, with more than one third of deaths being in the 65-84 age group.

The process of transmission may be simple or involve multiple steps. Some examples of routes of fecal–oral transmission include:

- water that has come in contact with feces (for example due to groundwater pollution from pit latrines) and is then not treated properly before drinking;

- by shaking someone's hand that has been contaminated by stool, changing a child's diapers, working in the garden or dealing with livestock or house pets.

- food that has been prepared in the presence of fecal matter;

- disease vectors, like houseflies, spreading contamination from inadequate fecal disposal such as open defecation;

- poor or absent hand washing after using the toilet or handling feces (such as changing diapers)

- poor or absent cleaning of anything that has been in contact with feces;

- sexual practices that may involve oral contact with feces, such as anilingus, coprophilia or "ass to mouth".

- eating feces, in children, or in a mental disorder called coprophagia

- eating soil (geophagia)

Waterborne diseases can have a significant impact on the economy, locally as well as internationally. People who are infected by a waterborne disease are usually confronted with related costs and not seldom with a huge financial burden. This is especially the case in less developed countries. The financial losses are mostly caused by e.g. costs for medical treatment and medication, costs for transport, special food, and by the loss of manpower. Many families must even sell their land to pay for treatment in a proper hospital. On average, a family spends about 10% of the monthly households income per person infected.

To avoid tick bites and infection, experts advise:

- Avoid tick-infested areas, especially during the warmer months.

- Wear light-colored clothing so ticks can be easily seen. Wear a long sleeved shirt, hat, long pants, and tuck pant legs into socks.

- Walk in the center of trails to avoid overhanging grass and brush.

- Clothing and body parts should be checked every few hours for ticks when spending time outdoors in tick-infested areas. Ticks are most often found on the thigh, arms, underarms, and legs. Ticks can be very small (no bigger than a pinhead). Look carefully for new "freckles".

- The use of insect repellents containing DEET on skin or permethrin on clothing can be effective. Follow the directions on the container and wash off repellents when going indoors.

- Remove attached ticks immediately.

Contracting the CTF virus is thought to provide long-lasting immunity against reinfection. However, it is always wise to be on the safe side and try to prevent tick bites.

Blood poses the greatest threat to health in a laboratory or clinical setting due to needlestick injuries ("e.g.", lack of proper needle disposal techniques and/or safety syringes). These risks are greatest among healthcare workers, including: nurses, surgeons, laboratory assistants, doctors, phlebotomists, and laboratory technicians. These roles often require the use of syringes for blood draws or to administer medications.

The Occupational Safety and Health Administration (OSHA) prescribes 5 rules that are required for a healthcare facility to follow in order to reduce the risk of employee exposure to bloodborne pathogens. They are:

- Written exposure control plan

- Engineering controls (Sharps containers, detachable and retractable needles, syringe caps, etc.)

- Safe Work Practices and Safety Devices

- Hepatitis B vaccine available to employees

- Education and post-exposure follow up

These controls, while general, serve to greatly reduce the incidence of bloodborne disease transmission in occupational settings of healthcare workers.

There are 26 different viruses that have been shown to present in healthcare workers as a result of occupational exposure. The most common bloodborne diseases are hepatitis B (HBV), hepatitis C (HCV), and human immunodeficiency virus (HIV). Exposure is possible through blood of an infected patient splashing onto mucous membranes; however, the greatest exposure risk was shown to occur during percutaneous injections performed for vascular access. These include blood draws, as well as catheter placement, as both typically use hollow bore needles. Preventative measures for occupational exposure include standard precautions (hand washing, sharp disposal containers), as well as additional education and preventative measures. Advancements in the design of safety engineered devices have played a significant role in decreasing rates of occupational exposure to bloodborne disease. According to the Massachusetts Sharps Injury Surveillance System, needle devices without safety features accounted for 53% of the 2010 reported sharps injuries. Safer sharps devices now have engineering controls, such as a protective shield over the needle, and sharps containers that have helped to decrease this statistic. These safer alternatives are highly effective in substantially reducing injuries. For instance, almost 83% of injuries from hollow bore needles can be prevented with the use of safer sharps devices.

"A. phagocytophilum" is transmitted to humans by "Ixodes" ticks. These ticks are found in the US, Europe, and Asia. In the US, "I. scapularis" is the tick vector in the East and Midwest states, and "I. pacificus" in the Pacific Northwest. In Europe, the "I. ricinus" is the main tick vector, and "I. persulcatus" is the currently known tick vector in Asia.

The major mammalian reservoir for "A. phagocytophilum" in the eastern United States is the white-footed mouse, "Peromyscus leucopus". Although white-tailed deer and other small mammals harbor "A. phagocytophilum", evidence suggests that they are not a reservoir for the strains that cause HGA. A tick that has a blood meal from an infected reservoir becomes infected themselves. If an infected tick then latches onto a human the disease is then transmitted to the human host and "A." "phagocytophilum" symptoms can arise.

"Anaplasma phagocytophilum" shares its tick vector with other human pathogens, and about 10% of patients with HGA show serologic evidence of coinfection with Lyme disease, babesiosis, or tick-borne meningoencephalitis.

Blood for blood transfusion is screened for many bloodborne diseases. Additionally, a technique that uses a combination of riboflavin and UV light to inhibit the replication of these pathogens by altering their nucleic acids can be used to treat blood components prior to their transfusion, and can reduce the risk of disease transmission.

A technology using the synthetic psoralen, amotosalen HCl, and UVA light (320–400 nm) has been implemented in European blood centers for the treatment of platelet and plasma components to prevent transmission of bloodborne diseases caused by bacteria, viruses and protozoa.

Mosquito-borne diseases, such as dengue fever and malaria, typically affect third world countries and areas with tropical climates. Mosquito vectors are sensitive to climate changes and tend to follow seasonal patterns. Between years there are often dramatic shifts in incidence rates. The occurrence of this phenomenon in endemic areas makes mosquito-borne viruses difficult to treat.

Dengue fever is caused by infection through viruses of the family Flaviviridae. The illness is most commonly transmitted by Aedes aegypti mosquitoes in tropical and subtropical regions. Dengue virus has four different serotypes, each of which are antigenically related but have limited cross-immunity to reinfection.

Although dengue fever has a global incidence of 50-100 million cases, only several hundreds of thousands of these cases are life-threatening. The geographic prevalence of the disease can be examined by the spread of the Aedes aegypti. Over the last twenty years, there has been a geographic spread of the disease. Dengue incidence rates have risen sharply within urban areas which have recently become endemic hot spots for the disease. The recent spread of Dengue can also be attributed to rapid population growth, increased coagulation in urban areas, and global travel. Without sufficient vector control, the dengue virus has evolved rapidly over time, posing challenges to both government and public health officials.

Malaria is caused by a protozoan called Plasmodium falciparum. P. falciparum parasites are transmitted mainly by the Anopheles gambiae complex in rural Africa. In just this area, P. falciparum infections comprise an estimated 200 million clinical cases and 1 million annual deaths. 75% of individuals afflicted in this region are children. As with dengue, changing environmental conditions have led to novel disease characteristics. Due to increased illness severity, treatment complications, and mortality rates, many public health officials concede that malaria patterns are rapidly transforming in Africa. Scarcity of health services, rising instances of drug resistance, and changing vector migration patterns are factors that public health officials believe contribute to malaria’s dissemination.

Climate heavily affects mosquito vectors of malaria and dengue. Climate patterns influence the lifespan of mosquitos as well as the rate and frequency of reproduction. Climate change impacts have been of great interest to those studying these diseases and their vectors. Additionally, climate impacts mosquito blood feeding patterns as well as extrinsic incubation periods. Climate consistency gives researchers an ability to accurately predict annual cycling of the disease but recent climate unpredictability has eroded researchers’ ability to track the disease with such precision.

Human granulocytic anaplasmosis (HGA) is a tick-borne, infectious disease caused by "Anaplasma phagocytophilum", an obligate intracellular bacterium that is typically transmitted to humans by ticks of the "Ixodes ricinus" species complex, including "Ixodes scapularis" and "Ixodes pacificus" in North America. These ticks also transmit Lyme disease and other tick borne diseases.

The bacteria infect white blood cells called neutrophils, causing changes in gene expression that prolong the life of these otherwise short-lived cells.

Person-to-person transmission is exceedingly unusual; and patients with melioidosis should not be considered contagious. Lab workers should handle "B. pseudomallei" under BSL-3 isolation conditions, as laboratory-acquired melioidosis has been described.

In endemic areas, people (rice-paddy farmers in particular) are warned to avoid contact with soil, mud, and surface water where possible. Case clusters have been described following flooding and cyclones and probably relate to exposure. Other case clusters have related to contamination of drinking water supplies. Populations at risk include patients with diabetes mellitus, chronic renal failure, chronic lung disease, or an immune deficiency of any kind. The effectiveness of measures to reduce exposure to the causative organism have not been established. A vaccine is not yet available.

Melioidosis is an infectious disease caused by a Gram-negative bacterium, "Burkholderia pseudomallei", found in soil and water. It is of public health importance in endemic areas, particularly in northeast Thailand, Vietnam, and northern Australia. It exists in acute and chronic forms. Signs and symptoms may include pain in chest, bones, or joints; cough; skin infections, lung nodules, and pneumonia.

"B. pseudomallei" was previously classed as part of the "Pseudomonas" genus; until 1992, it was known as "Pseudomonas pseudomallei". It is phylogenetically related closely to "Burkholderia mallei" which causes glanders, an infection primarily of horses, donkeys, and mules. The name melioidosis is derived from the Greek "melis" (μηλις) meaning "a distemper of asses" with the suffixes -oid meaning "similar to" and -osis meaning "a condition", that is, a condition similar to glanders.

The arboviruses have expanded their geographic range and infected populations that had no recent community knowledge of the diseases carried by the "Aedes aegypti" mosquito. Education and community awareness campaigns are necessary for prevention to be effective. Communities are educated on how the disease is spread, how they can protect themselves from infection and the symptoms of infection. Community health education programs can identify and address the social/economic and cultural issues that can hinder preventative measures. Community outreach and education programs can identify which preventative measures a community is most likely to employ. Leading to a targeted prevention method that has a higher chance of success in that particular community. Community outreach and education includes engaging community health workers and local healthcare providers, local schools and community organizations to educate the public on mosquito vector control and disease prevention.

Sporotrichosis can be diagnosed in domestic and wild mammals. In veterinary medicine it is most frequently seen in cats and horses. Cats have a particularly severe form of cutaneous sporotrichosis and also can serve as a source of zoonotic infection to persons who handle them and are exposed to exudate from skin lesions.

Ticks should be removed promptly and carefully with tweezers and by applying gentle, steady traction. The tick's body should not be crushed when it is removed and the tweezers should be placed as close to the skin as possible to avoid leaving tick mouthparts in the skin; mouthparts left in the skin can allow secondary infections. Ticks should not be removed with bare hands. Hands should be protected by gloves and/or tissues and thoroughly washed with soap and water after the removal process.

A match or flame should not be used to remove a tick. This method, once thought safe, can cause the tick to regurgitate, expelling any disease it may be carrying into the bite wound.

A canine vector-borne disease (CVBD) is one of "a group of globally distributed and rapidly spreading illnesses that are caused by a range of pathogens transmitted by arthropods including ticks, fleas, mosquitoes and phlebotomine sandflies." CVBDs are important in the fields of veterinary medicine, animal welfare, and public health. Some CVBDs are of zoonotic concern.

Many CVBD infect humans as well as companion animals. Some CVBD are fatal; most can only be controlled, not cured. Therefore, infection should be avoided by preventing arthropod vectors from feeding on the blood of their preferred hosts. While it is well known that arthropods transmit bacteria and protozoa during blood feeds, viruses are also becoming recognized as another group of transmitted pathogens of both animals and humans.

Some "canine vector-borne pathogens of major zoonotic concern" are distributed worldwide, while others are localized by continent. Listed by vector, some such pathogens and their associated diseases are the following:

- Phlebotomine sandflies (Psychodidae): "Leishmania amazonensis", "L. colombiensis", and "L. infantum" cause visceral leishmaniasis (see also canine leishmaniasis). "L. braziliensis" causes mucocutaneous leishmaniasis. "L. tropica" causes cutaneous leishmaniasis. "L. peruviana" and "L. major" cause localized cutaneous leishmaniasis.

- Triatomine bugs (Reduviidae): "Trypanosoma cruzi" causes trypanosomiasis (Chagas disease).

- Ticks (Ixodidae): "Babesia canis" subspecies ("Babesia canis canis", "B. canis vogeli", "B. canis rossi", and "B. canis gibsoni" cause babesiosis. "Ehrlichia canis" and "E. chaffeensis" cause monocytic ehrlichiosis. "Anaplasma phagocytophilum" causes granulocytic anaplasmosis. "Borrelia burgdorferi" causes Lyme disease. "Rickettsia rickettsii" causes Rocky Mountain spotted fever. "Rickettsia conorii" causes Mediterranean spotted fever.

- Mosquitoes (Culicidae): "Dirofilaria immitis" and "D. repens" cause dirofilariasis.

Scrapie is a fatal, degenerative disease that affects the nervous systems of sheep and goats. It is one of several transmissible spongiform encephalopathies (TSEs), which are related to bovine spongiform encephalopathy (BSE or "mad cow disease") and chronic wasting disease of deer. Like other spongiform encephalopathies, scrapie is caused by a prion. Scrapie has been known since 1732, and does not appear to be transmissible to humans.

The name scrapie is derived from one of the clinical signs of the condition, wherein affected animals will compulsively scrape off their fleeces against rocks, trees, or fences. The disease apparently causes an itching sensation in the animals. Other clinical signs include excessive lip smacking, altered gaits, and convulsive collapse.

Scrapie is infectious and transmissible among conspecifics, so one of the most common ways to contain it (since it is incurable) is to quarantine and destroy those affected. However, scrapie tends to persist in flocks and can also arise apparently spontaneously in flocks that have not previously had cases of the disease. The mechanism of transmission between animals and other aspects of the biology of the disease are only poorly understood, and these are active areas of research. Recent studies suggest prions may be spread through urine and persist in the environment for decades.

Scrapie usually affects sheep around three to five years of age. The potential for transmission at birth and from contact with placental tissues is apparent. No evidence indicates scrapie is infectious to humans.