Back in public school — and I blame myself for this, but the total lack of institutional integrity probably didn’t help — I had little to no appreciation of the hard sciences. In fact, I hated them. The only way I passed chemistry with a C was by cheating.
After somehow clearing astronomy and geology in college and having gotten the two hard science credits on my transcript required for a social sciences degree, I swore to God I would never take a science class again. And I haven’t.
But at times, over a decade after having graduated, I sometimes wish I had majored in biology because it’s so gosh-darn fascinating and still such a poorly understood subject. Of all the knowable knowledge in the discipline, what percentage do you suppose humanity has accumulated in the amalgamation of all the published research in the world? Probably not a lot — probably less than a single percent.
The biological world, I have come to appreciate, is wild beyond imagination.
Consider toxoplasmosis, a protozoan infection affecting up to a third of the global population and as much as 90% of the population in some European countries — the vast, vast majority of affected individuals unaware that they have it.
And its providence and implications are even more fantastical than its prevalence.
Toxoplasmosis is caused by infection with the protozoan Toxoplasma gondii, an obligate intracellular parasite. The infection produces a wide range of clinical syndromes in humans, land and sea mammals, and various bird species. T gondii has been recovered from locations throughout the world, except Antarctica…
T gondii infects a large proportion of the world’s population (perhaps one third) but uncommonly causes clinically significant disease…
Congenital toxoplasmosis usually is a subclinical infection…
.In most immunocompetent individuals, primary or chronic (latent) T gondii infection is asymptomatic. A small percentage of these patients eventually develop retinochoroiditis, lymphadenitis, or, rarely, myocarditis and polymyositis.
Related to the issue of subclinical infection (an infection that causes no apparent symptoms), it is not posited with credibility that Alzheimer’s and similar neurodegenerative conditions may be caused by undetected, long-term infections.
So where does toxoplasmosis in humans come from? Feces-laden cat litter, mostly — at least in the modern world.
Continuing via Medscape:
T gondii has 2 distinct life cycles. The sexual cycle occurs only in cats, the definitive host. The asexual cycle occurs in other mammals (including humans) and various strains of birds…
A cat becomes infected with T gondii by eating contaminated raw meat, wild birds, or mice.  The organism’s sexual cycle then begins in the cat’s gastrointestinal (GI) tract…
During a primary infection, the cat can excrete millions of oocysts daily for 1-3 weeks…
T gondii oocysts, tachyzoites, and bradyzoites can cause infection in humans. Infection can occur by ingestion of oocysts following the handling of contaminated soil or cat litter or through the consumption of contaminated water or food sources.
T gondii oocysts are ingested in material contaminated by feces from infected cats. Oocysts may also be transported to food by flies and cockroaches.
This is partly why I don’t subscribe to atheistic materialism as an explanatory worldview: to claim that a protozoan pathogen, by random chance, managed to evolve to infiltrate meat eaten by cats, then replicate itself in the gastrointestinal tract to be excreted in feces, and then transported from said feces by insects in search of new hosts defies belief. There is too much artistry in the process for that to be a product of non-design.
Among other potential symptoms, one that toxoplasmosis exerts in infected humans is increased recklessness — with real-world implications. Consider, for instance, the findings of this study, published in BMC Infectious Diseases, that tied toxoplasmosis to an increased risk of traffic accidents:
The subjects with latent toxoplasmosis have significantly increased risk of traffic accidents than the noninfected subjects. Relative risk of traffic accidents decreases with the duration of infection. These results suggest that ‘asymptomatic’ acquired toxoplasmosis might in fact represent a serious and highly underestimated public health problem, as well as an economic problem.
The difference between a fatal car crash and safe travel on any given day could be due to an untreated infection in one or both of the drivers passed to them through their kitty’s litterbox.
Stranger than fiction.