Photo Credit – FAO
# 6946
Yesterday, in my Sunday Morning Avian Flu Roundup, I briefly mentioned the reappearance of H7N3 in central Mexico.
This morning, we have an official statement posted on SAGARPA’s (Mexico’s Ministry of Agriculture, Livestock, Rural Development, Fisheries and Food) newsroom that provides details on the extent of the outbreak, and the plans in place to contain it.
SENASICA, mentioned below, is a sector agency of SAGARPA. The following is a machine translation from the original Spanish text, after which I’ll return with a little more.
SENASICA Strengthen epidemiological surveillance and control of the movement of poultry products in Guanajuato by the outbreak of Avian Influenza AH7N3
Mexico City, February 17, 2013
- The owner of SAGARPA, Enrique Martinez y Martinez, instructed the chief director of SENASICA, Enrique Sanchez Cruz, reinforcing diagnostic activities and narrow the movement controls on poultry products affected area.
- In the surrounding area without the presence of virus, vaccination is enhanced, in order to prevent the occurrence of this disease.
Upon completion of laboratory studies to determine the sequencing of the virus affecting poultry farms in Guanajuato Bachoco company, the National Health Service, Food Safety and Quality (SENASICA) confirmed that this is a virus of Avian Influenza AH7N3 high pathogenicity, equal to that had arisen in the states of Jalisco and Aguascalientes, so did the notification regarding the World Organization for Animal Health (OIE).
The decentralized body of the Ministry of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA), reported that due to the anti-epidemic actions among these epidemiological surveillance, we have located five more affected farms, which have 12 production units with the virus, of which ten of these farms are of broiler chickens (laying eggs for broiler production) and two commercial laying (birds producing eggs for human consumption).
It was further reported that nine are in Dolores Hidalgo, a Juventino Rosas in another in San Felipe Torres Mochas and one in San Luis de la Paz, which have a combined population of about one million birds, all owned by the Bachoco company.
According to the instructions of the owner of SAGARPA, Enrique Martinez y Martinez, were reinforced and diagnostic activities narrowed the movement controls, and in areas that have not been affected has intensified preventive vaccination, in order to avoid in poultry virus effects.
Also began laundering activities, cleaning and disinfection of facilities and equipment of each of the farms affected farms, which were quarantined and protocols as established in international health, applies the depopulation. It should be mentioned that the number of birds that could be killed, be determined with specific diagnoses that reveal the presence of influenza AH7N3.
In coordination with technical staff of the state government, and with the support of the military and federal and state public safety, are enabling 13 internal checkpoints on the main road routes, in order to control the movement of birds products and byproducts. Additionally, we conducted verification of egg hatchery for broiler birds.
The SENASICA reiterated that this virus is unique to birds, so there is no risk to public health, also urged poultry farmers in the area to provide timely notice and reinforce biosecurity measures on their farms.
Although a considerable threat to the poultry industry, H7 viruses are viewed as posing far less of a public health threat. Human infections have rarely been reported, and most have been mild.
The most recent report of human H7 infection comes from last summer’s Jalisco, Mexico outbreak, and the details were reported in MMWR: Mild H7N3 Infections In Two Poultry Workers - Jalisco, Mexico.
While global surveillance and reporting on novel avian viruses in humans is spotty at best, some known H7 cases include:
Chart lifted and edited from CIDRAP’s excellent overview Avian Influenza (Bird Flu): Implications for Human Disease showing known H7 avian flu infections in humans over the two decades.
One H7N7 fatality was reported a decade ago in the Netherlands. Generally the H7 viruses usually only produce mild symptoms in humans. Of course – H7s - like all influenza viruses, are constantly mutating and evolving.
What is mild, or relatively benign today, may not always remain so. In 2008 we saw a study in PNAS that suggested the H7 virus might just be inching its way towards better adaptation to humans.
Our knowledge of influenza A viruses that circulated in humans before the the 20th century is extremely limited, but since that time we only know of HA (hemagglutinin) types H1, H2, and H3 causing human epidemics.
In the past some scientists have questioned whether any of the other HA subtypes are even capable of sparking a human pandemic. An excellent discussion of this topic can be found in the 2008 paper:
The Next Influenza Pandemic: Can It Be Predicted?
Jeffery K. Taubenberger, MD, PhD, David M. Morens, MD, and Anthony S. Fauci, MD
(EXCERPT – but read the whole thing)
It is currently impossible to predict the emergence of a future pandemic other than to strongly suspect that one will eventually occur, or to predict when or where a future pandemic will occur, what subtype it will be, and what degree of morbidity and mortality it will produce. Even though concern over the emergence of an H5N1 pandemic is clearly warranted, if for no other reason than its current high case–fatality rate, experts must also anticipate and plan for many other possibilities for pandemic emergence.
The argument for the pandemic threat posed by HA subtypes other than H1, H2, and H3 gained traction a year ago when virologists Ron Fouchier and Yoshihiro Kawaoka each independently demonstrated genetic changes to the H5N1 virus that would make it more transmissible in mammals.
See Science Publishes The Fouchier Ferret Study and Nature Publishes The Kawaoka H5N1 Study for details.
The fact that we haven’t seen an H5 or H7 pandemic virus emerge in the past 150 years is, admittedly, reassuring. But it serves as no guarantee that it can’t happen sometime in the future.
So we watch outbreaks of avian influenzas, even those with relatively low public health risks today, for any signs of change.
