International Events

Avian Influenza A(H5N1) in Dairy Products USA – Colorado July 3, 2024

  • On April 1, 2024, the World Health Organization (WHO) was notified of a laboratory-confirmed human case of Influenza A(H5N1) by the United States National Focal Point (NFP) for International Health Regulations (IHR).
  • The patient exhibited symptoms on March 27 and had a history of exposure to dairy products (cows) infected with Influenza A(H5N1) in Texas. This confirmed human case of Influenza A(H5N1) is the first to be detected in 2024 and the second in the country. No additional human cases of Influenza A(H5N1) have been identified.
  • On July 3, 2024, another human case of highly pathogenic avian influenza (HPAI) A(H5) was identified in the United States, specifically in Colorado. This is the fourth case associated with a multi-state outbreak of Influenza A(H5N1) in dairy cows and the first in Colorado. Previous cases were reported in Texas (1) and Michigan (2). As in previous cases, the infected individual worked on a dairy farm where cows were confirmed to have avian influenza.  The patient reported only eye redness, was treated with oseltamivir, and recovered.   The Centers for Disease Control and Prevention (CDC) closely monitored influenza surveillance systems in affected states and observed no unusual influenza activity among people, including syndromic surveillance.
Risk Assessment:
Reports indicate that this human case was exposed to dairy products in Texas, where HPAI A(H5N1) was confirmed in dairy herds.
Most human cases occur after exposure to infected animals or contaminated environments. Reported human infections tend to be mild clinically. More human infections are expected given the continued detection of the virus in poultry or swine herds, although it is rare to report Influenza A infections in cattle. Currently, the spread among dairy cattle herds in four U.S. states is being assessed.
From 2003 to April 2024, a total of 889 cases and 463 deaths (52% fatality rate) due to Influenza A(H5N1) were reported worldwide from 23 countries. The last human case reported before the current one was in March 2024 in Vietnam. The Texas human case is the fourth reported in the Americas, with the previous case reported in Chile in March 2023.
On June 11, 2024, the WHO announced that a four-year-old child in India was infected with avian influenza H9N2 – a different strain from H5N1 – but recovered after experiencing seizures, respiratory distress, fever, and abdominal pain. The H9N2 virus has infected around 100 people globally since 1998, with this being the second human case in India.
Current epidemiological and virological evidence suggests that Influenza A (H5), A(H9N2), A(H1)v, and A(H3N8) viruses  have not acquired the ability to sustain human-to-human transmission, so the likelihood of human-to-human spread remains low.
There are no specific vaccines available to prevent human infections with Influenza A(H5N1), but candidate vaccines for H5 virus prevention in humans have been developed for pandemic preparedness purposes.
Based on available information, this case does not change the CDC's assessment of the risk posed by H5N1 avian influenza to the general public in the U.S., which remains low. However, this development underscores the importance of recommended precautions for people exposed to infected animals. Individuals closely or prolongedly exposed or unprotected to sick birds or other animals (including cows) or contaminated environments face a higher risk of A(H5N1) avian influenza infection.

CDC Activities
This case was detected through the implementation of surveillance and testing strategies recommended by the CDC for people exposed to the virus. In addition to enhanced and targeted surveillance, the CDC has also:
  • Conducted multiple calls with state and local health departments to increase preparedness.
  • Taken actions to improve the availability of personal protective equipment for farm workers.
  • Updated interim recommendations for worker protection to include those handling dairy cows.
  • Made multiple calls with groups representing farm workers.
  • Launched a paid digital awareness campaign in affected counties to provide farm workers with information on avian influenza prevention and what to do if symptoms appear
WHO Recommendations for Risk Management:
  • The diversity of zoonotic influenza viruses requires increased surveillance in both animals and humans, comprehensive investigation of all zoonotic infections, and pandemic planning to prevent a viral mutation that could facilitate human-to-human transmission. The WHO recommends seasonal influenza vaccination for poultry workers.
  • Global surveillance is crucial to detect virological, epidemiological, and clinical changes associated with the spread of influenza viruses that may impact human and animal health. Cooperation between the animal and human health sectors is essential, along with systematic monitoring of suspected human cases.
  • Travelers to countries known to have outbreaks of animal influenza should avoid farms, contact with animals in live animal markets, entering areas where animals may be slaughtered, or touching any surfaces contaminated with animal feces. Travelers should also wash their hands frequently with soap and water, and the general public should follow good food safety and hygiene practices.
  • All laboratory-confirmed human infections caused by a new subtype of influenza virus must be reported under the International Health Regulations (IHR, 2005).
  • The WHO does not recommend special screening at points of entry or restrictions on travel concerning the current state of influenza viruses at the human-animal interface
Last Update : 10 July 2024 10:17 AM
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