Michigan Confirms Human H1N2v Swine Flu Case in Fair Exhibitor
核心洞察
Michigan health officials confirmed a human case of influenza A H1N2 variant (搜索) (swine flu) in an Ionia County resident who exhibited swine at the Kent County Youth Fair held Aug. 3–8.
The CDC confirmed the presumptive positive result on Aug. 14, and health departments are contacting swine exhibitors and their families to identify additional symptomatic cases.
No human vaccine specifically protects against swine flu, and the seasonal flu vaccine does not cover it, though antivirals such as oseltamivir and zanamivir can treat infection.
Michigan health officials are investigating a confirmed case of influenza A H1N2 variant (搜索), commonly known as swine flu, in an Ionia County resident who exhibited swine at the Kent County Youth Fair. The Michigan Department of Health and Human Services (搜索) (MDHHS) reported that the individual initially tested presumptive positive for the virus at the MDHHS Bureau of Laboratories, and the Centers for Disease Control and Prevention (搜索) (CDC) confirmed the result on Friday, Aug. 14.
The fair was held Aug. 3–8 at the Grand Agricultural Center of West Michigan in Lowell. The Kent County Health Department and MDHHS are contacting swine exhibitors and their families who visited the swine barns during the fair to determine whether others developed symptoms after potential exposure to infected pigs. The Kent County Health Department has also alerted area health care providers to watch for patients with respiratory symptoms who report exposure to swine or attendance at the fair.
Transmission and Clinical Presentation
Swine can carry influenza viruses that differ from those that commonly circulate among people. Although infections in people are rare, swine influenza viruses can spread from pigs to humans, primarily through respiratory droplets when infected animals cough or sneeze. Symptoms can resemble seasonal influenza and may include fever, cough, runny nose, body aches, nausea, vomiting, and diarrhea.
Health officials note that the time from exposure to illness can be as long as 10 days, although symptoms most commonly develop within about three days. Variant influenza infections can sometimes cause severe illness, including pneumonia, hospitalization, and, in rare cases, death. People at higher risk include children younger than five, adults 65 and older, pregnant people, and those with certain chronic health conditions or weakened immune systems.
Prevention and Treatment
Health officials say no human vaccine exists specifically for swine flu, and the seasonal flu vaccine does not protect against swine influenza. Antiviral medications, including oseltamivir and zanamivir, can treat influenza infections, and early treatment is particularly important for people at higher risk of complications.
MDHHS recommends that people attending fairs, farms, or livestock exhibits avoid eating or drinking in livestock barns or show rings, and keep toys, pacifiers, cups, bottles, strollers, and similar items out of pig areas. People at high risk for serious influenza complications should avoid contact with pigs and swine barns. Officials also recommend getting an annual influenza vaccination, which protects against seasonal flu even though it does not protect against swine flu.
Pandemic Risk and Surveillance
The CDC's assessment notes that sporadic infections and even localized outbreaks among people with variant influenza viruses may occur. All influenza viruses have the capacity to change, and it is possible that variant viruses may change such that they infect people easily and spread easily from person-to-person. The CDC continues to monitor closely for variant influenza virus infections and reports cases of H3N2v and other variant influenza viruses weekly in FluView.
The CDC's Influenza Risk Assessment Tool (IRAT) currently lists three North American swine viruses as having at least some pandemic potential. While the pandemic risk from swine variant viruses is currently thought to be low, these viruses continue to reinvent themselves as they circulate in pigs, prompting close attention whenever they jump species to humans. Since most people never see a doctor or get tested for uncomplicated flu-like symptoms, it is assumed that many swine variant infections go unreported. During a small outbreak of H3N2v (n=13) 15 years ago, researchers estimated that fewer than one in every 200 cases was identified.
The health departments continue to monitor for additional illnesses associated with the fair and potential exposure to swine influenza.