due to improper vaccinations, health officials warned Thursday, after a five-month-old rescue puppy from Azerbaijan tested positive for the virus last year despite meeting import requirements.

Last year's case where a puppy fell ill just three days after arriving with its adopted family in Pennsylvania was blamed on faulty paperwork.

The animal was certified to have been inoculated against rabies in Azerbaijan, but testing revealed it and seven others out of the 33 dogs and one cat brought across the border had not been fully vaccinated.

It is fatal in virtually every case without treatment, with victims symptoms progressing from a fever to seizures in days.

It is deadly in almost every case left untreated — and has an incubation period of 20 to 60 days.

The majority of rabies cases result from being bitten by an infected dog.

There are about 55,000 cases of rabies worldwide each year with over 95 percent occurring in Africa and Asia.

In the latest case, the puppy arrived at O'Hare International Airport in Chicago, Illinois, on June 10 of last year and was sent to an adoptive family.

A total of 15 people were given the drug rabies postexposure prophylaxis as a precaution, in case they had been infected.

Blood tests revealed seven other animals on the shipment — all dogs — had not been adequately vaccinated against rabies by the time they arrived.

Animals are considered vaccinated against rabies from 28 days after receiving their initial jab

But in some cases — like with these animals — if a too small initial dose is given the vaccine may not spark immunity.