An unusual event accompanied a routine gathering of friends for a poker game – the house cat gave birth. As a result, all the participants in the gathering fell ill with Q fever, a disease caused by the bacterium Coxiella burnetii. One of the friends, who suffered from underlying medical conditions, did not survive.
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On February 14, 1987, in the city of Halifax, Nova Scotia, Canada, a group of about a dozen poker enthusiasts gathered. This was not their first game. They used to meet two or three times a week. But this time something unusual happened in the room where they played. Unbeknownst to them, the hosts’ cat was lying in her basket in the corner, giving birth. A litter of three adorable kittens came into the world. Sadly, one of the kittens did not survive.
On March 5, roughly three weeks after that gathering, the host was admitted to the local hospital with pneumonia that serology identified as Q fever. By March 16, all eleven other poker players had been hospitalized as well. Each was diagnosed with Q fever and treated with the antibiotic tetracycline. One patient died—a man with pre-existing heart disease who also contracted a secondary bacterial infection. All the others responded to treatment and recovered. An autopsy revealed the disease-causing bacteria in the deceased patient’s lungs.
Q fever is common in wildlife and in livestock worldwide, except in New Zealand. It was first reported and characterized in 1935 in the state of Queensland, Australia. Debate persists over whether the Q in the disease’s name refers to the state or to the word “Query,” because for a long time the cause of the disease was unknown. The culprits are the bacteria Coxiella burnetii, small, short rod-shaped bacteria and obligate intracellular parasites that resemble the better-known Rickettsia in both shape and life cycle.
Coxiella burnetii bacteria in cultured cells. Source: NIH
The main natural carriers of the bacteria are sheep, goats, and cattle, but they are also found in other mammals, such as pets (dogs and cats) and various rodents. Carriers typically show no signs of illness, and the disease manifests chiefly during pregnancy. At that time the bacteria multiply in the female reproductive organs, uterus, and placenta, and even invade fetal cells. This leads to miscarriages or to the birth of infected and sick offspring, some of whom do not survive.
During parturition the bacteria are shed to the environment in every possible way: in feces, urine, milk, and uterine secretions. They also disperse as infectious aerosols, thereby entering the respiratory tracts of anyone nearby. When the bacteria reach humans, the illness begins with symptoms common to many diseases: headaches, fever, chills, and coughing. Pneumonia, hepatitis, endocarditis, and inflammation of other organs can follow, sometimes with fatal outcomes. Pregnant women may miscarry. In most cases, antibiotic treatment halts the disease’s progression and aids recovery.
The epidemiological investigation, led by Joan Langley of Dalhousie University, ruled out links between the patients and rural areas, exposure to farm animals or wildlife, or consumption of unpasteurized dairy products. It was later discovered that all twelve patients were connected through the poker meetings, and specifically the session during which the cat gave birth. Examination of the cat revealed that her uterus was infected with the bacterium, and the two surviving kittens had been exposed as well. The link to the birth was conclusively confirmed when it was found that the host’s children, who spent time with the cat but were not present during the delivery, had not been exposed. Everyone in the room at the time of the birth, when a bacterial aerosol was spead from the uterus into the poorly ventilated space or in the few hours afterward, inhaled the bacteria and became ill.
The remaining question is how the cat became infected, given that this was not a rural area. The investigators hypothesized that the cat had preyed on an infected mouse. If correct, the disease may not be confined to rural regions.
The event was described in the paper’s title and in accompanying reports as “Poker Players’ Pneumonia.”
Hebrew editing: Smadar Raban
English editing: Elee Shimshoni
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Dror is a member of Little, big Science's board of directors. He holds a PhD in Molecular Biology and has authored textbooks and articles for the general public, primarily in microbiology as well as other biological subjects. Dror taught microbiology and cell biology for more than 30 years at the Open University and other institutions.
