Illustration of bacteria.

News of a new "seal flu" has many fearing a repeat of the 2009 swine flu outbreak that infected more than 5.7 million in the United States before peaking as a level 5 on the WHO's 6-point pandemic alert. The H3N8 flu virus was discovered after the mysterious death of nearly 200 harbor seals off the United States' northeastern coasts. Described as "a combination we haven't seen in disease before" researchers warned that the new strain of influenza A could have severe repercussions for human health.

The real shock of the story may be the public realization that such doe-eyed creatures could cause harm. While mosquitoes and ticks, those pesky harbingers of West Nile, Dengue Fever, cholera, Lyme disease and Kyasanur fever (among other assorted viral, fungal and bacterial pathogens), are universally hated, it's hard to believe the earth's more cuddly creatures could breed evil. Here's another 13 to ruin your next trip to the petting zoo:


Peacocks are dying in droves in Pakistan's Thar Desert region in an outbreak scientists believe is linked to Newcastle disease. Highly contagious in birds, the viral infection is currently rare in humans. Its unique replication properties make it a potential candidate for agroterrorism, but more positive headways been made in its use as a human cancer treatment.


Found primarily in Latin America, armadillos are better known for their unique defense mechanism than their role as a global disease vector. Their shell, however, shields leprosy, a rare bacterial infection that attacks the skin and nervous system. Though associated more with the Bible than modern medicine, the disease remains active throughout the world — with armadillos responsible for more than a third of infections in the United States.


The world's largest mammal offers plenty of real estate for influenza A, a viral flu strain with the most potential for interspecies transmission. Luckily, the chances for accidental contact remain slim — just another reason to skip the whale meat.

Monkeys and apes

Described by malaria researchers as a "reservoir for human disease," monkeys and apes are widely known for harboring emerging zoonotic diseases. The HIV virus originated in African monkeys and strains of malaria, Ebola, and monkeypox virus continue to be created or transmitted by monkey and ape populations — not to mention the cases of measles, rabies, tuberculosis, salmonellosis, shigellosis, amebiasis, balatidiasis, herpes B, giardiasis and helminthes believed to have appeared first in man's closest relative.

Dogs and cats

While many a dog-lover cheered reports of a feline parasite's negative impact on human dopamine production, man's best friend carries its own risks. Though undulant fever is more commonly associated with other species, human cases of the leptospirosis bacteria, an infection whose effect ranges from flu-like symptoms to liver and kidney failure, encephalitis, and pulmonary involvement, have been reported to originate in dogs.

Prairie dogs

More commonly associated with rats, plague seems to have chosen prairie dogs as its modern rodent host. One leg of a complex threesome that includes mice and fleas, prairie dog coteries across North America have been struck by a mass outbreak of bubonic and sylvatic plague. To cull the epidemic, the U.S. Department of Agriculture has implemented a mass fumigation campaign.


While flying foxes are their natural reservoir, the Hendra and Nipah viruses have adapted to survive within horses where they take residence alongside anthrax. Worse, equine encephalitis virus, a pathogen listed as a global priority by the Global Early Warning System for Major Animal Diseases, Including Zoonoses, has spread globally. Transmitted by mosquitos, the virus can be fatal in both horses and humans.

Rabbits and hares

Elmer Fudd had a point. Beneath their long, soft ears, rabbits and hares carry a host of mites and ringworms and can breed tularemia, a bacterial infection listed as a potential bio-weapon.

Guinea pigs and hamsters

However popular with the preschool set, guinea pigs and hamsters are still rodents. Next time your kid asks to bring one home remember — these furry beasts are disease vectors of lymphocytic choriomeningitis, leptospirosis, yersiniosis and salmonellosis. Handle with gloves.

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