Peru confirms H5N1 avian flu in marine mammals, part of southward spread

Sea lions

Mariano Mantel / Flickr cc

Veterinary authorities in Peru yesterday confirmed H5N1 avian influenza in sea lions and a dolphin, adding more reports of detections in mammals as the virus continues its push into Central and South America.

Peru's National Agrarian Health Service (SENASA) said surveillance for marine species on the country's coasts are part of its response to outbreaks in poultry. Tests on three sea lions found dead in November and one dolphin were positive for H5N1, SENASA said in a statement, which was translated and posted by Avian Flu Diary, an infectious disease news blog.

In a follow-up, SENASA said at least 585 sea lions and 55,000 wild birds have been found dead in seven of the country's coastal nature preserves, likely due to avian flu.

Also, media reports citing Peru's health ministry said tests on a zoo lion in central Peru identified H5N1 as the cause of death.

The reports add to a growing number of detections in mammals, including recent reports from the United Kingdom and H5N1 in farmed minks in Spain. The United States has so far reported 110 detections in mammal species. The H5N1 clade circulating in birds, poultry, and an increasing number of mammals has a mutation that makes the virus more recognizable by mammalian airway cells.

Seven human H5N1 infections have been reported, all involving people who had close contact with poultry. Some illnesses were mild, but some were severe or fatal. So far, no human-to-human transmission has been reported.

Poultry outbreaks surge in Central and South America

The World Organization for Animal Health (WOAH) last week raised concerns about not only the spread of the highly pathogenic avian flu to new countries in Central and South America, but also the speed of the spread over a 4-month period, with occasional spillovers to humans and mammals. The most recent human case was reported in a 9-year-old girl from Ecuador.

Newly affected countries include Bolivia, Colombia, Costa Rica, Ecuador, Honduras, Panama, Peru, and Venezuela. Chile reported its first high-path outbreaks in 20 years.

WOAH said outbreaks have already led to the loss of 1.2 million poultry in Central and South America, a concern given that poultry is one of the most consumed animal proteins in the region, with the fast-growing poultry sector providing income to thousands of families. It and the United Nations' Food and Agriculture Organization (FAO) recently created an expert group on avian flu, which met in December to make recommendations, which included stronger biosecurity and surveillance steps.

Outbreaks continue in other regions; WOAH notes mammal detections

In a separate report that covers global avian flu activity in the first 3 weeks of January, WOAH said there were 70 outbreaks in poultry during the period and 90 events involving other birds, mainly in Europe, but also in the Americas and Asia, affecting 3 million birds that died or were culled. Most of the activity involves the current H5N1 subtype.

Based on seasonal patterns, WOAH said it expects the number of outbreaks in animals to peak in the weeks ahead. It urged countries to maintain surveillance and biosecurity measures and to report the detections in timely manner in poultry and nonpoultry species.

"WOAH also stresses the importance of reporting outbreaks of avian influenza in unusual hosts, as it has been noted that the virus has been increasingly detected in mammals in recent months, a situation that should be monitored," it said, adding that high-quality information is needed to support early detection and response to potential threats to both animals and people.

More detections in US poultry

In the United States, a steady stream of outbreaks continue in poultry. In updates over the past few days, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) reported more outbreaks in three states, including California, Maine, and Wyoming. Most involve backyard flocks, but one of three new outbreaks in California occurred at a commercial duck breeding farm in Merced County that houses 29,100 birds.

So far, the H5N1 outbreaks in the United States, which began in February 2022, have led to the loss of nearly 58.3 million birds across 47 states.

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