There is a disease that is something like what you are looking for. Toxoplasmosis is spread by undercooked meat that is infected with spores, or contact with cat feces, usually through litterboxes.
It's asymptomatic for the most part, as far as what we think of typical sickness symptions. In some places of the world, it's pandemic, meaning that some 90% of the population are infected.
What's interesting is that researcher Jaroslav Flegr has looked into how toxoplasmosis affects human behavior:
His work on how toxoplasmosis—an infection caused by the protozoan
parasite T. gondii—influences personality, sex ratios, and rates
of traffic accidents, has received coverage in The Atlantic,
Salon, and The Guardian. Flegr maintains that toxoplasmosis
might increase the rate of traffic accidents by as much as one million
collisions per year. He also believes that T. gondii
contributes to suicides and mental disorders such as schizophrenia.
His work has shown that Toxoplasmosis increases sociability and risk-taking in people who are infect by it:
Feeling sociable or reckless? You might have toxoplasmosis, an
infection caused by the microscopic parasite Toxoplasma gondii, which
the CDC estimates has infected about 22.5 percent of Americans older
than 12 years old. Researchers tested participants for T. gondii
infection and had them complete a personality questionnaire. They
found that both men and women infected with T. gondii were more
extroverted and less conscientious than the infection-free
participants. These changes are thought to result from the parasite's
influence on brain chemicals, the scientists write in the May/June
issue of the European Journal of Personality.
“Toxoplasma manipulates the behavior of its animal host by increasing
the concentration of dopamine and by changing levels of certain
hormones,” says study author Jaroslav Flegr of Charles University in
Prague, Czech Republic.
Although humans can carry the parasite, its life cycle must play out
in cats and rodents. Infected mice and rats lose their fear of cats,
increasing the chance they will be eaten, so that the parasite can
then reproduce in a cat's body and spread through its feces [see
“Protozoa Could Be Controlling Your Brain,” by Christof Koch,
Consciousness Redux; Scientific American Mind, May/June 2011].
There is even some extreme speculation that, since the origin of toxoplasmosis infection is ultimately from cats, and it causes changes in behavior, it may have played a role in the development and spread of early civilization, when cats and humans first began to dwell together in the middle east.
Toxoplasma – the brain parasite that influences human culture
Carriers tend to show long-term personality changes that are small but
statistically significant. Women tend to be more intelligent,
affectionate, social and more likely to stick to rules. Men on the
other hand tend to be less intelligent, but are more loyal, frugal and
mild-tempered. The one trait that carriers of both genders share is a
higher level of neuroticism – they are more prone to guilt, self-doubt
In individuals cases, these effects may seem quirky or even charming
but across populations, they can have a global power. T.gondii
infection is extremely common and rates vary greatly from country to
country. While only 7% of Brits carry the parasite, a much larger 67%
of Brazilians are infected. Given that the parasite alters behaviour,
infection on this scale could lead to sizeable differences in the
general personalities of people of different nationalities. This is
exactly what Lafferty found.
Neuroticism is one of the most widely-studied of all psychological
traits and Lafferty found that levels in different countries
correlated well with the levels of T.gondii infection. The parasites’
presence was also related to aspects of culture associated with
neuroticism. Countries where infection was common were more likely to
have ‘masculine sex roles’, characterized by greater differences
between the sexes and their part in society and a stronger focus on
work, ambition and money rather than people and relationships.
Strongly infected societies were also more likely to avoid risk and
embrace strict rules and regulations.
So, if instead of through spores in undercooked meat, or cat feces, your disease spread through normal social contact, the same way that a cold or the flu spreads through handshakes, etc, and the disease made people more sociable and liable to take risks, you have a model for a disease that would quickly become pandemic.