#17,417
Three weeks ago Chile's National Fisheries and Aquaculture Service (SERNAPESCA) reported more than 2,200 mammals had been found dead along the coast during the first 3 months of 2023, most (if not all) believed due to avian H5N1.
According to the latest report from SERNAPESCA, authorities have now recovered more than 4,300 animal carcasses from the roughly 4000 miles of Chilean shoreline. While only a small fraction have been tested for H5N1, avian flu is believed the cause of death for the vast majority of these creatures.While that number was 17 times greater than all of the animals stranded in Chile in 2022 (n=131), the toll has grown progressively worse, nearly doubling over the past 21 days.
To date, nearly 10% of Chile's Humboldt penguin population has been lost, as well as over 3,300 sea lions.
First the update from SERNAPESCA, after which I'll return with a postscript.
Sernapesca reports that two Chilean dolphins tested positive for bird flu
Wednesday April 19, 2023
There are already 4,347 specimens of common sea lions, Humboldt penguins, chungungos and smaller cetaceans that have been stranded dead on the coasts of our country this year, mainly in the north.
The epidemiological situation of highly pathogenic avian influenza (HPAI) by H5 subtype of Eurasian lineage has continued to spread. There are already 10 regions of the country that have registered marine fauna protected by the Fisheries and Aquaculture Law with positivity for avian influenza, with positive cases from Arica to Biobío.
To date, a total of 35 specimens of marine animals confirmed as positive for HPAI have been counted, corresponding to: 2 chungungos, 25 sea lions, 4 Humboldt penguins, 2 spiny porpoises, and now 2 Chilean dolphins recently confirmed as positive for Influenza. Avian, one in the Maule region and another in Ñuble.
Sernapesca reported that they continue to register strandings of dead marine animals on the Chilean coasts. In total, 3,347 specimens of sea lions, 958 Humboldt penguins, 16 chungungos, 15 porpoises and 11 Chilean dolphins have already been reported. The northern macrozone concentrates the highest mortality of these animals, with the region of Arica and Parinacota leading the ranking with 1,486 dead marine animals, followed by Antofagasta with 752, Atacama with 623, Tarapacá with 484 and Coquimbo with 412. Meanwhile, In the southern zone, the Biobío region stands out with 200 dead marine animals, associated with the Avian Influenza contingency.
Soledad Tapia, National Director of Sernapesca indicated that "we have already recorded 2,415% more dead stranded marine animals than last year in the country, and this is attributed to the phenomenon of highly pathogenic avian influenza that we are facing not only in Chile, but also in various countries in South and North America, Europe and Asia”.
Species at risk of conservation
From Sernapesca they expressed concern about the situation of the Chilean dolphin, also known as the black tonina. “This is an endemic species of our country, that is, it is a small cetacean that travels almost exclusively on the coasts of Chile. It is distributed from Valparaíso to the south of Navarino Island and Cape Horn, and it is a protected species. We registered two positive cases of avian influenza in this species, which we attribute to the fact that they share a habitat with wolves, since, like these mammals, Chilean dolphins are coastal species," said Soledad Tapia.
Another worrying situation is the conservation of the Humboldt penguin, which has already recorded 933 casualties in this avian flu contingency. “A total population of no more than 11,000 Humboldt penguins in our country is estimated, which is not very numerous, because this species has a highly localized distribution. In general, it is estimated that the Humboldt penguin population is in continuous decline, and its category is vulnerable according to the International Union for Conservation of Nature. In this contingency we are close to losing 10% of this species, and that certainly worries us," said the national director of Sernapesca.
In this context of the Avian Influenza emergency, work has been reinforced with other entities such as the Presidential Delegations, Regional Governments, SAG, Seremías, Municipalities and others, in order to support the active surveillance plan throughout the coastline with the in order to reduce the risks of viral circulation of said disease, through the detection, testing and final disposal of affected animals.
The service reiterated the emphatic call to people who are on the coastline not to touch or handle marine animals stranded alive or dead, keep their distance and report to 800 320 032.
The $64 question - as yet unanswered - is how this virus is managing to spread so rapidly among marine mammals in South America (and elsewhere). Since there are several plausible alternative routes of transmission (e.g. consumption of infected birds, `high environmental load' of the virus, etc.), mammal-to-mammal transmission can be difficult to prove.
Nevertheless, a preprint published last February on a similar outbreak in Peru (see First Mass Mortality of Marine Mammals Caused by Highly Pathogenic Influenza Virus (H5N1) in South America) couldn't exclude the possibility.
The authors wrote:
The source of the HPAI affecting these sea lions was very probably the large number of infected birds/carcasses on the Peruvian coastline (4). Sea lions may be infected by close contact with these carcasses and even through their consumption (see Fig. 2 F). However, the transmission pathway remains unknown until now. Such high levels of mortality in a social animal are worrisome.We cannot exclude direct transmission among sea lions due to their colonial breeding, and because many animals died simultaneously in groups. In fact, based on recent research suggesting the first mammal-to-mammal infection in minks (Neovison vison) (9) and the large number of sea lions currently affected, we cannot rule out that the virus has adapted to mammals and that sea lion-sea lion transmission has begun in Peru; this should be urgently investigated.Moreover, the mass mortality of animals that can weigh around 350 kg (10) produces an enormous biomass of infected tissue, which could perpetuate the transmission of H5N1 and other pathogens. This could have serious consequences for the ecosystem and human health.
Stay tuned.
