Information:  - In biology, a species (abbreviated sp., with the plural form species abbreviated spp.) is the basic unit of biological classification and a taxonomic rank. A species is often defined as the largest group of organisms in which two individuals can produce fertile offspring, typically by sexual reproduction. While this definition is often adequate, looked at more closely it is often problematic. For example, in a species complex, the boundaries between closely related species become unclear or disappear altogether. Other ways of defining species include similarity of DNA, morphology, or ecological niche. The presence of locally adaptive traits may further subdivide species into infraspecific taxa such as subspecies.  - Flaviviridae is a family of viruses. Humans and other mammals serve as natural hosts. They are primarily spread through arthropod vectors (mainly ticks and mosquitoes). The family gets its name from the Yellow Fever virus, the type virus of "Flaviviridae"; "flavus" means yellow in Latin, and Yellow fever in turn was named because of its propensity to cause jaundice in victims. There are currently over 100 species in this family, divided among four genera. Diseases associated with this family include: hepaciviruses, hepatitis, pestiviruses, hemorrhagic syndromes, fatal mucosal disease, flavivirus, hemorrhagic fever, encephalitis, and the birth defect microcephaly.  - Pestivirus is a genus of viruses, in the family Flaviviridae. Viruses in the genus "Pestivirus" infect mammals, including members of the family Bovidae (which includes, but is not limited to, cattle, sheep, and goats) and the family Suidae (which includes various species of swine). There are currently four species in this genus including the type species Bovine viral diarrhea virus 1. Diseases associated with this genus include: hemorrhagic syndromes, abortion, fatal mucosal disease.  - Suidae is a family of artiodactyl mammals commonly called pigs, hogs, or boars. In addition to numerous fossil species, up to sixteen extant species are currently recognized, classified into between four and eight genera. The family includes the domestic pig, "Sus scrofa domesticus" or "Sus domesticus", in addition to numerous species of wild pig, such as the babirusa "Babyrousa babyrussa" and the warthog "Phacochoerus aethiopicus". All suids, or swine, are native to the Old World, ranging from Asia to Europe and Africa.  - Yellow fever is an acute viral disease. In most cases, symptoms include fever, chills, loss of appetite, nausea, muscle pains particularly in the back, and headaches. Symptoms typically improve within five days. In some people within a day of improving, the fever comes back, abdominal pain occurs, and liver damage begins causing yellow skin. If this occurs, the risk of bleeding and kidney problems is also increased. The disease is caused by the yellow fever virus and is spread by the bite of an infected female mosquito. It infects only humans, other primates, and several species of mosquitoes. In cities, it is spread primarily by mosquitoes of the "Aedes aegypti" type. The virus is an RNA virus of the genus "Flavivirus". The disease may be difficult to tell apart from other illnesses, especially in the early stages. To confirm a suspected case, blood sample testing with polymerase chain reaction is required. A safe and effective vaccine against yellow fever exists and some countries require vaccinations for travelers. Other efforts to prevent infection include reducing the population of the transmitting mosquito. In areas where yellow fever is common and vaccination is uncommon, early diagnosis of cases and immunization of large parts of the population is important to prevent outbreaks. Once infected, management is symptomatic with no specific measures effective against the virus. The second and more severe phase results in death in up to half of people without treatment. Yellow fever causes 200,000 infections and 30,000 deaths every year, with nearly 90% of these occurring in Africa. Nearly a billion people live in an area of the world where the disease is common. It is common in tropical areas of South America and Africa, but not in Asia. Since the 1980s, the number of cases of yellow fever has been increasing. This is believed to be due to fewer people being immune, more people living in cities, people moving frequently, and changing climate. The disease originated in Africa, from where it spread to South...  - The Bovidae are the biological family of cloven-hoofed, ruminant mammals that includes bison, African buffalo, water buffalo, antelopes, gazelles, sheep, goats, muskoxen, and domestic cattle. A member of this family is called a bovid. Consisting of 143 extant species and 300 known extinct species, the family Bovidae consists of eight major subfamilies apart from the disputed Peleinae and Pantholopinae. The family evolved 20 million years ago, in the early Miocene.  - Bovine Viral Diarrhea ( BVD ) or Bovine Viral Diarrhoea ( UK English ) , and previously referred to as Bovine Virus Diarrhoea ( BVD ) , is a significant economic disease of cattle which is endemic in the majority of countries throughout the world . The causative agent , bovine viral diarrhea virus ( BVDV ) is a member of the Pestivirus genus of the family Flaviviridae . BVD infection results in a wide variety of clinical signs , due to its immunosuppressive effects , as well as having a direct effect on respiratory disease and fertility . In addition , BVD infection of a susceptible dam during a certain period of gestation can result in the production of a persistently infected ( PI ) fetus . PI animals recognise intra-cellular BVD viral particles as `` self '' and shed virus in large quantities throughout life ; they represent the cornerstone of the success of BVD as a disease .    After reading the paragraphs above, we are interested in knowing the entity with which 'bovine virus diarrhea' exhibits the relationship of 'instance of'. Find the answer from the choices below.  Choices: - 1  - biological classification  - biology  - case  - cattle  - century  - chain  - climate  - damage  - dna  - domestic pig  - extinct  - family  - five  - four  - genus  - group  - hepatitis  - human  - infectious  - may  - morphology  - muscle  - name  - pig  - rank  - reproduction  - skin  - taxonomic rank  - two  - type species  - vaccine  - viral disease  - virus  - water
Answer:
viral disease