To date, there have been 53 confirmed human cases of H5N1 avian influenza in seven states according to the U.S. Centers for Disease Control and Prevention.  Half the cases were attributed to exposure to infected dairy herds in California with 385 cases confirmed.  The remainder involved workers depopulating flocks infected with HPAI in Colorado, Washington State, Michigan and Oregon.  All the poultry and bovine-acquired cases were characterized by conjunctivitis and in some cases mild transitory upper respiratory symptoms.

The California Department of Public Health is investigating a sporadic case in a child demonstrating mild upper respiratory involvement.  The case responded to antiviral and supportive therapy, unlike the case in British Colombia where the patient is receiving  intensive care.

Public health authorities in numerous states recommend seasonal influenza vaccination for all personnel coming into contact with live poultry in order to avert a possible recombinant event. This may be possible between H5N1 avian influenza virus in a flock and a human strain that may result in a new zoonotic virus that may develop the capability for contagion subject to further mutations.

An unfortunate concordance of high demand through pre-Thanksgiving and Christmas coupled with reduced supply as a result of avian influenza has increased the prices of eggs on the shelf.

Both local TV stations and print media have commented on higher prices with unfavorable comparisons to the lower per dozen values during the fall of 2023 when flocks had been replenished after previous depopulation due to HPAI.

Year-to-date losses as a result of infection have attained 22 million above routine mortality of 2 million per month and flock depletion of 15 million per month due to age, Replacements through replacement of started pullets  are progressing at approximately 22 million per month.

The price discovery system used by buyers and the industry accentuates the magnitude of both extreme increases and declines in price. This has been to the detriment of the industry since 2022.  The USDA New York price posted each working day is unfortunately related to the commercial benchmark price.  A CME quotation for Midwest large would be a more equitable method of establishing price.

Given the incidence rate of HPAI among egg production complexes since the beginning of October and given that migratory waterfowl have not completed their southward movement, additional outbreaks can be anticipated.  Avian influenza H5N1 is now regionally and seasonally endemic and accordingly the APHIS policy of attempted  “stamping out” of infection is inappropriate. To maintain a complement of 320 million hens in production to satisfy demand with acceptable retail prices for conventional eggs will require vaccination as an adjunct to biosecurity as introduced in the E.U. and long practiced in China and Mexico among other nations with intensive poultry industries. Even the most comprehensive structural and operational biosecurity does not provide absolute protection against aerogenous infection.

Based on an examination of serum samples from 115 dairy farm workers collected during July and August, the U.S. Centers for Disease Control and Prevention (CDC) has called for more extensive serologic surveillance to ascertain the incidence rate among individuals exposed to herds with and without bovine influenza H5N1 strain B3.13.

Among the 115 samples, eight yielded antibodies to the specific virus, representing seven percent of those surveyed.  Of those that were obviously exposed and developed circulating antibodies, four reported clinical symptoms including upper respiratory involvement and conjunctivitis with four cases asymptomatic.  This suggests that a proportion of those infected may not develop symptoms after exposure to the current virus circulating in U.S. dairy herds.

Dr. Nirav Shah, Principal Deputy Director of the CDC, stated, “These findings mean that we need to cast a wider net in terms of who is offered a test so that we can identify, treat and isolate those individuals.  Serologic testing at this time is essential to understand the epidemiology of zoonotic bovine influenza. 

To treat and isolate individuals would require rapid testing applying PCR since detection of antibodies is only possible weeks after exposure.  Of greater importance in both antigen and antibody testing is to determine that there is no contagion through assay of nasal swabs and subsequent serum samples collected from household and other contacts with individuals known to have been infected.

It is also of importance to ascertain why only seven percent of farm workers in contact with herds shedding H5N1 acquired infection.  The circumstances favoring zoonotic transmission including the specific tasks or location of workers, the use of PPE or individual susceptibility should be evaluated.

It is anticipated that CDC and specialists in the molecular biology of influenza viruses are conducting sequence analysis to detect any mutations that may favor zoonotic infection or even human-to-human transmission.