At the genetic level, an AIV can be usually be identified as an HPAI virus if it has a multibasic cleavage site in the HA protein, which contains additional residues in the HA gene. Most AIVs are LPAI. Notable HPAI viruses include HPAI H5N1 and HPAI H7N9. HPAI viruses have been a major disease burden in the 21st century, resulting in the death of large numbers of birds. In H7N9s case, some circulating strains were originally LPAI but became HPAI by acquiring the HA multibasic cleavage site. Avian H9N2 is also of concern because although it is LPAI, it is a common donor of genes to H5N1 and H7N9 during reassortment.Migratory birds can spread influenza across long distances. An example of this was when an H5N1 strain in 2005 infected birds at Qinghai Lake, China, which is a stopover and breeding site for many migratory birds, subsequently spreading the virus to more than 20 countries across Asia, Europe, and the Middle East. AIVs can be transmitted from wild birds to domestic free-range ducks and in turn to poultry through contaminated water, aerosols, and fomites. Ducks therefore act as key intermediates between wild and domestic birds. Transmission to poultry typically occurs in backyard farming and live animal markets where multiple species interact with each other. From there, AIVs can spread to poultry farms in the absence of adequate biosecurity. Among poultry, HPAI transmission occurs through aerosols and contaminated feces, cages, feed, and dead animals.
A diagnosis of infective endocarditis is definite if either the following pathological or clinical criteria are met:
One of these pathological criteria:

Histology or culture of cardiac vegetation, embolized vegetation, or intracardiac abscess from the heart finds microorganisms
Active endocarditisOne of these combinations of clinical criteria

Two major clinical criteria
One major and three minor criteria
Five minor criteriaDiagnosis of infective endocarditis is possible if one of the following combinations of clinical criteria is met:

One major and one minor criteria
Three minor criteria are fulfilled

Major criteria
Positive blood culture with typical IE microorganism, defined as one of the following:
Typical microorganism consistent with IE from two separate blood cultures, as noted below:
Viridans-group streptococci, or
Streptococcus bovis including nutritional variant strains, or
HACEK group, or
Staphylococcus aureus, or
Community-acquired enterococci, in the absence of a primary focus
Microorganisms consistent with IE from persistently positive blood cultures defined as:
Two positive cultures of blood samples drawn >12 hours apart, or
Three or a majority of ≥four separate blood cultures (with first and last sample drawn at least one hour apart)
Coxiella burnetii detected by at least one positive blood culture or IgG antibody titer for Q fever phase 1 antigen >1:800.