The disease can be prevented in horses with the use of vaccinations. These vaccinations are usually given together with vaccinations for other diseases, most commonly WEE, VEE, and tetanus. Most vaccinations for EEE consist of the killed virus. For humans there is no vaccine for EEE so prevention involves reducing the risk of exposure. Using repellent, wearing protective clothing, and reducing the amount of standing water is the best means for prevention

A recent study from The Cleveland Clinic reported that BK viremia load > 185 000 copies/ml at the time of first positive BKV diagnosis - to be the strongest predictor for BKVAN (97% specificity and 75% sensitivity). In addition the BKV peak viral loads in blood reaching 223 000 copies/ml at any time was found to be predictive for BKVAN (91% specificity and 88% sensitivity) .

The rationale behind using leflunomide in BKVAN comes from its combined immunosuppressive and antiviral properties. Two studies consisting of 26 and 17 patients who developed BKVAN on a three-drug regimen of tacrolimus, MMF, and steroids had their MMF replaced with leflunomide 20–60 mg daily. 84 and 88% of patients, respectively had clearance or a progressive reduction in viral load and a stabilization or improvement of graft function (7). In a study conducted by Teschner et al. in 2009, 12/13 patients who had their MMF exchanged with leflunomide cleared the virus by 109 days. In a case series, there was improvement or stabilization in 23/26 patients with BKVAN after switching MMF to leflunomide.

There are no dosing guidelines for leflunomide in BKVAN. Patient to patient variability has made dosing and monitoring of leflunomide extremely difficult.

- Study of 26 and 17 patients were dosed between 20 mg/day and 60 mg/day with trough levels of 50—100 µg/ml. Failure was seen in patients with leflunomide plasma levels < 40 µg/ml.

- One study of 21 patients found that low levels ( 40 µg/ml) had similar effects on the rate of viral clearance. Those with higher levels had more adverse events (hematologic, hepatic).

- In the study by Teschner et al., dosages and drug concentration showed no correlation with substantial variation from person to person.

- In the Teschner study, low drug concentrations were associated with decrease in viral load. This makes it difficult to determine whether or not reduction of viral load or addition of leflunomide was the cause for viral clearance.

Cats can be protected from H5N1 if they are given a vaccination, as mentioned above. However, it was also found that cats can still shed some of the virus but in low numbers.

If a cat is exhibiting symptoms, they should be put into isolation and kept indoors. Then they should be taken to a vet to get tested for the presence of H5N1. If there is a possibility that the cat has Avian Influenza, then there should be extra care when handling the cat. Some of the precautions include avoiding all direct contact with the cat by wearing gloves, masks, and goggles. Whatever surfaces the cat comes in contact with should be disinfected with standard household cleaners.

They have given tigers an antiviral treatment of Oseltamivir with a dose of 75 mg/60 kg two times a day. The specific dosage was extrapolated from human data, but there hasn't been any data to suggest protection. As with many antiviral treatments, the dosage depends on the species.

There is currently no specific treatment for the virus. A vaccine is available, but only experimentally. It has not been released to the public due to the risk it poses to already exposed birds.

Therapeutic intervention is limited to treating secondary infections. The individual bird can sometimes recover, but this is rare. If only the feathers are affected and the bird suffers no other symptoms, it can usually experience an acceptable quality of life. But if the bird's beak or nails are affected, veterinarians will recommend euthanasia.

The management of the disease lies thus mostly in prevention. Every new bird that enters a pen with other birds should be quarantined first and be tested for BFDV. Birds which are known carriers should not be introduced into new pens, especially not if those contain young birds.

Prophylaxis by vaccination, as well as preventive measures like protective clothing, tick control, and mosquito control are advised. The vaccine for KFDV consists of formalin-inactivated KFDV. The vaccine has a 62.4% effectiveness rate for individuals who receive two doses. For individuals who receive an additional dose, the effectiveness increases to 82.9%. Specific treatments are not available.

The theory that cancer could be caused by a virus began with the experiments of Oluf Bang and Vilhelm Ellerman in 1908 who first show that avian erythroblastosis (a form of chicken leukemia) could be transmitted by cell-free extracts. This was subsequently confirmed for solid tumors in chickens in 1910-1911 by Peyton Rous.

By the early 1950s it was known that viruses could remove and incorporate genes and genetic material in cells. It was suggested that these new genes inserted into cells could make the cell cancerous. Many of these viral oncogenes have been discovered and identified to cause cancer.

The main viruses associated with human cancers are human papillomavirus, hepatitis B and hepatitis C virus, Epstein-Barr virus, human T-lymphotropic virus, Kaposi's sarcoma-associated herpesvirus (KSHV) and Merkel cell polyomavirus. Experimental and epidemiological data imply a causative role for viruses and they appear to be the second most important risk factor for cancer development in humans, exceeded only by tobacco usage. The mode of virally induced tumors can be divided into two, "acutely transforming" or "slowly transforming". In acutely transforming viruses, the viral particles carry a gene that encodes for an overactive oncogene called viral-oncogene (v-onc), and the infected cell is transformed as soon as v-onc is expressed. In contrast, in slowly transforming viruses, the virus genome is inserted, especially as viral genome insertion is an obligatory part of retroviruses, near a proto-oncogene in the host genome. The viral promoter or other transcription regulation elements in turn cause overexpression of that proto-oncogene, which in turn induces uncontrolled cellular proliferation. Because viral genome insertion is not specific to proto-oncogenes and the chance of insertion near that proto-oncogene is low, slowly transforming viruses have very long tumor latency compared to acutely transforming viruses, which already carry the viral oncogene.

Hepatitis viruses, including hepatitis B and hepatitis C, can induce a chronic viral infection that leads to liver cancer in 0.47% of hepatitis B patients per year (especially in Asia, less so in North America), and in 1.4% of hepatitis C carriers per year. Liver cirrhosis, whether from chronic viral hepatitis infection or alcoholism, is associated with the development of liver cancer, and the combination of cirrhosis and viral hepatitis presents the highest risk of liver cancer development. Worldwide, liver cancer is one of the most common, and most deadly, cancers due to a huge burden of viral hepatitis transmission and disease.

Through advances in cancer research, vaccines designed to prevent cancer have been created. The hepatitis B vaccine is the first vaccine that has been established to prevent cancer (hepatocellular carcinoma) by preventing infection with the causative virus. In 2006, the U.S. Food and Drug Administration approved a human papilloma virus vaccine, called Gardasil. The vaccine protects against four HPV types, which together cause 70% of cervical cancers and 90% of genital warts. In March 2007, the US Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) officially recommended that females aged 11–12 receive the vaccine, and indicated that females as young as age 9 and as old as age 26 are also candidates for immunization.

West Nile virus can be sampled from the environment by the pooling of trapped mosquitoes via ovitraps, carbon dioxide-baited light traps, and gravid traps, testing blood samples drawn from wild birds, dogs, and sentinel monkeys, as well as testing brains of dead birds found by various animal control agencies and the public.

Testing of the mosquito samples requires the use of reverse-transcriptase PCR (RT-PCR) to directly amplify and show the presence of virus in the submitted samples. When using the blood sera of wild birds and sentinel chickens, samples must be tested for the presence of WNV antibodies by use of immunohistochemistry (IHC) or enzyme-linked immunosorbent assay (ELISA).

Dead birds, after necropsy, or their oral swab samples collected on specific RNA-preserving filter paper card, can have their virus presence tested by either RT-PCR or IHC, where virus shows up as brown-stained tissue because of a substrate-enzyme reaction.

West Nile control is achieved through mosquito control, by elimination of mosquito breeding sites such as abandoned pools, applying larvacide to active breeding areas, and targeting the adult population via lethal ovitraps and aerial spraying of pesticides.

Environmentalists have condemned attempts to control the transmitting mosquitoes by spraying pesticide, saying the detrimental health effects of spraying outweigh the relatively few lives that may be saved, and more environmentally friendly ways of controlling mosquitoes are available. They also question the effectiveness of insecticide spraying, as they believe mosquitoes that are resting or flying above the level of spraying will not be killed; the most common vector in the northeastern United States, "Culex pipiens", is a canopy feeder.

There is no cure for EEE. Treatment consists of corticosteroids, anticonvulsants, and supportive measures (treating symptoms) such as intravenous fluids, tracheal intubation, and antipyretics. About four percent of humans known to be infected develop symptoms, with a total of about six cases per year in the US. A third of these cases die, and many survivors suffer permanent brain damage.

Infection with Japanese encephalitis confers lifelong immunity. There are currently three vaccines available: SA14-14-2, IC51 (marketed in Australia and New Zealand as JESPECT and elsewhere as IXIARO) and ChimeriVax-JE (marketed as IMOJEV). All current vaccines are based on the genotype III virus.

A formalin-inactivated mouse-brain derived vaccine was first produced in Japan in the 1930s and was validated for use in Taiwan in the 1960s and in Thailand in the 1980s. The widespread use of vaccine and urbanization has led to control of the disease in Japan, Korea, Taiwan, and Singapore. The high cost of this vaccine, which is grown in live mice, means that poorer countries have not been able to afford to give it as part of a routine immunization program.

The most common adverse effects are redness and pain at the injection site. Uncommonly, an urticarial reaction can develop about four days after injection. Vaccines produced from mouse brain have a risk of autoimmune neurological complications of around 1 per million vaccinations. However where the vaccine is not produced in mouse brains but in vitro using cell culture there is little adverse effects compared to placebo, the main side effects are headache and myalgia.

The neutralizing antibody persists in the circulation for at least two to three years, and perhaps longer. The total duration of protection is unknown, but because there is no firm evidence for protection beyond three years, boosters are recommended every three years for people who remain at risk. Furthermore, there is also no data available regarding the interchangeability of other JE vaccines and IXIARO.

In September 2012 the Indian firm Biological E. Limited has launched an inactivated cell culture derived vaccine based on SA 14-14-2 strain which was developed in a technology transfer agreement with Intercell and is a thiomersal-free vaccine.

Personal protective measures can be taken to greatly reduce the risk of being bitten by an infected mosquito:

- Using insect repellent on exposed skin to repel mosquitoes. EPA-registered repellents include products containing DEET (N,N-diethylmetatoluamide) and picaridin (KBR 3023). DEET concentrations of 30% to 50% are effective for several hours. Picaridin, available at 7% and 15% concentrations, needs more frequent application. DEET formulations as high as 30% are recommended for children over two months of age. Protect infants less than two months of age by using a carrier draped with mosquito netting with an elastic edge for a tight fit.

- When using sunscreen, apply sunscreen first and then repellent. Repellent should be washed off at the end of the day before going to bed.

- Wear long-sleeve shirts, which should be tucked in, long pants, socks, and hats to cover exposed skin. Insect repellents should be applied over top of protective clothing for greater protection. Do not apply insect repellents underneath clothing.

- The application of permethrin-containing ("e.g.", Permanone) or other insect repellents to clothing, shoes, tents, mosquito nets, and other gear for greater protection. Permethrin is not labeled for use directly on skin. Most repellent is generally removed from clothing and gear by a single washing, but permethrin-treated clothing is effective for up to five washings.

- Be aware that most mosquitoes that transmit disease are most active during twilight periods (dawn and dusk or in the evening). A notable exception is the Asian tiger mosquito, which is a daytime feeder and is more apt to be found in, or on the periphery of, shaded areas with heavy vegetation. They are now widespread in the United States, and in Florida they have been found in all 67 counties.

- Staying in air-conditioned or well-screened housing, and/or sleeping under an insecticide-treated bed net. Bed nets should be tucked under mattresses and can be sprayed with a repellent if not already treated with an insecticide.

Estimated percent of new cancers attributable to the virus worldwide in 2002. NA indicates not available.

The association of other viruses with human cancer is continually under research.

No treatment exists for the viral infection. Antibiotics may help prevent secondary infections.

Vaccination is available in different forms, usually for naive flocks.

Good biosecurity measures should be maintained including adequate quarantine, isolation, separation of different age groups and disinfection.

The scientific study of the genetics of MVEV has been facilitated by the construction and manipulation of an infectious cDNA clone of the virus.

There are no vaccines or any other treatments specifically for Saint Louis encephalitis virus, although one study showed that early use of interferon-alpha2b may decrease the severity of complications.

Cats with Avian Influenza exhibit symptoms that can result in death. They are one of the few species that can get Avian Influenza. The specific virus that they get is H5N1, which is a subtype of Avian Influenza. In order to get the virus, cats need to be in contact with waterfowl, poultry, or uncooked poultry that are infected. Two of the main organs that the virus affects are the lungs and liver.

MVEV is a mosquito-borne virus that is maintained in a bird-mosquito-bird cycle. Water birds from the order Ciconiiformes, including herons and cormorants, provide the natural reservoir for MVEV. The major mosquito vector is "Culex annulirostris". Human infection occurs only through bites from infected mosquitoes; the virus cannot be transmitted from person to person.

There is no specific treatment for Japanese encephalitis and treatment is supportive, with assistance given for feeding, breathing or seizure control as required. Raised intracranial pressure may be managed with mannitol. There is no transmission from person to person and therefore patients do not need to be isolated.

A breakthrough in the field of Japanese encephalitis therapeutics is the identification of macrophage receptor involvement in the disease severity. A recent report of an Indian group demonstrates the involvement of monocyte and macrophage receptor CLEC5A in severe inflammatory response in Japanese Encephalitis infection of the brain. This transcriptomic study provides a hypothesis of neuroinflammation and a new lead in development of appropriate therapeutic against Japanese encephalitis.

Vaccination is the only known method to prevent the development of tumors when chickens are infected with the virus. However, administration of vaccines does not prevent transmission of the virus, i.e., the vaccine is not sterilizing. However, it does reduce the amount of virus shed in the dander, hence reduces horizontal spread of the disease. Marek's disease does not spread vertically. The vaccine was introduced in 1970 and the scientist credited with its development is Dr. Ben Roy Burmester and Dr. Frank J Siccardi. Before that, Marek's disease caused substantial revenue loss in the poultry industries of the United States and the United Kingdom. The vaccine can be administered to one-day-old chicks through subcutaneous inoculation or by "in ovo" vaccination when the eggs are transferred from the incubator to the hatcher. "In ovo" vaccination is the preferred method, as it does not require handling of the chicks and can be done rapidly by automated methods. Immunity develops within two weeks.

The vaccine originally contained the antigenically similar turkey herpesvirus, which is serotype 3 of MDV. However, because vaccination does not prevent infection with the virus, the Marek's disease virus has evolved increased virulence and resistance to this vaccine. As a result, current vaccines use a combination of vaccines consisting of HVT and gallid herpesvirus type 3 or an attenuated MDV strain, CVI988-Rispens (ATCvet code: ).

There is currently no vaccine available. The primary method of disease prevention is minimizing mosquito bites, as the disease is only transmitted by mosquitoes. Typical advice includes use of mosquito repellent and mosquito screens, wearing light coloured clothing, and minimising standing water around homes (e.g. removing Bromeliads, plant pots, garden ponds). Staying indoors during dusk/dawn hours when mosquitos are most active may also be effective. Bush camping is a common precipitant of infection so particular care is required.

PBFD has the potential to become a major threat to all species of wild parrots and to modern aviculture, due to international legal and illegal bird trade. Cases of PBFD have now been reported in at least 78 psittacine species. At least 38 of 50 Australian native species are affected by PBFD, both captive and in the wild. In 2004, PBFD was listed as a key threatening process by the Australian Commonwealth Government for the survival of five endangered species, including one of the few remaining species of migratory parrots, the orange-bellied parrot, of which only an estimated 60 mating pairs remained in 2006.

Mosquitoes, primarily from the genus "Culex", become infected by feeding on birds infected with the Saint Louis encephalitis virus. Infected mosquitoes then transmit the Saint Louis encephalitis virus to humans and animals during the feeding process. The Saint Louis encephalitis virus grows both in the infected mosquito and the infected bird, but does not make either one sick. Only infected mosquitoes can transmit Saint Louis encephalitis virus. Once a human has been infected with the virus it is not transmissible from that individual to other humans.

Antiviral drugs, that target infections with RRV. Patients are usually managed with simple analgesics, anti-inflammatories, anti-pyretics and rest while the illness runs its course.

An anthroponotic disease, or anthroponosis, is an infectious disease in which a disease causing agent carried by humans is transferred to other animals. It may cause the same disease or a different disease in other animals. Since humans do not generally inflict bite wounds on other animals, the method of transmissions is always a "soft" contact such as skin to skin transmission. An example is chytridiomycosis which can be spread by humans with the fungus on their skin handling frogs with bare hands.

The reverse situation, a disease transmitted from animals to humans, is known as zoonotic.

It can also be defined as a human-to-human infection with no animal vector.

Since opportunistic infections can cause severe disease, much emphasis is placed on measures to prevent infection. Such a strategy usually includes restoration of the immune system as soon as possible, avoiding exposures to infectious agents, and using antimicrobial medications ("prophylactic medications") directed against specific infections.