Although the role of the cat colony caregivers may appear to be well intentioned, it is actually misguided and puts humans, pets and other organisms at risk. 

Initially, these caregivers were meant to feed and befriend stray cats in an effort (in part) to gain their trust and ultimately bring them in for sterilization procedures.

However, this archaic strategy has not resulted in a decrease of strays and by all indications, has had the opposite effect.

An astonishing 73 percent of feral cats in Hawaii are infected with Toxoplasma gondii (a single-celled parasite) that poses risk to those immune-compromised or pregnant. Moreover, an infected juvenile cat typically sheds roughly a million cysts out into the environment.

Once in the environment, these cysts are rather resilient and may remain viable for a year, until an unsuspecting species (be it mouse, pet or human) becomes infected.

Numerous other studies have shown that surface runoff spreads Toxoplasma cysts into larger water bodies, therefore resulting in seal (such as monk) and other infections. In fact,

13 percent of otter deaths have been attributed to Toxoplasma infection.

Current estimates of human Toxoplasma infection in the U.S. range from 10-25 percent, while the prevalence of infection in Europe may be upward of 50 percent, report ProMED Digest (Feb. 20, 2012) and Microbe (January 2012).

Although human infection is generally benign in healthy, non-pregnant individuals, some studies suggest that Toxoplasma infection may actually alter mental and physiological capabilities in both humans and mice.

In fact, a recent study reported in August’s Journal of Clinical Psychology indicates that human Toxoplasma infection results in brain inflammation, cellular damage and clinical depression; and ultimately suggests that one is seven times more likely to commit suicide as a result of this infection.

Likewise, another study in Denmark has linked Toxoplas-ma infection to bipolar and schizophrenia disorders, and infected women were 53 percent more likely to attempt suicide.

Sadly, the common practice of feeding non-native species often extends to birds and mongoose. Similar to feral cats harboring Toxoplasma, hookworm, roundworm, heartworm, ringworm, feline leukemia virus, Salmonella and fleas (to name a few), birds and mongoose can harbor parasites and microbes that can be transmitted to other species such as humans and their pets.

The feeding of exotic species also results in an increase in host organisms that can serve as reservoirs for a diverse array of dangerous parasites. For example, birds can carry avian malaria and pox viruses that can then be transmitted, and in many cases cause illness and/or death in endangered native bird species.

Indeed, ceasing to feed exotic and/or feral species may seem a cruel option. However, given the current costs to the overall health of humans, pets and native species, this option is one that is long overdue.

It is doubtful that we have the resources to capture, treat and vaccinate the majority of species carrying parasites that pose a risk to all of us.

However, simply ignoring the risk and continuing to feed and encourage proliferation of these species is not logical, and certainly not sustainable as these colonies continue to grow.

For the safety of the whole community, it is time to discourage the cat caretaking practice — on both private and municipal land — and instead implement strategies that will be truly successful in protecting the health of all in the long run.

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Matthew C. Tuthill is assistant professor of molecular biology and microbiology at the University of Hawaii’s Kapiolani Community College Math and Sciences Department.