Parasites are usually cast as nature’s villains: blood-feeding mosquitoes, screwworms, intestinal worms and disease-carrying ticks that survive at a host’s expense.
But Kenyan entomologist Dino Martins argues that this overlooked branch of life also helps shape ecosystems, evolution and human history.
In his new book, “Hidden Creatures: Luscious Leeches, Bashful Botflies, and the Wondrous, History-Shaping World of Parasites.”
Martins travels from African forests to scientific archives, examining organisms that inspire disgust but also wonder. The book combines field observations with accounts of researchers and patients whose work helped reveal how parasites spread disease.
Evidence suggests that some parasitic diseases are spreading or rebounding. Malaria remains the largest parasitic threat to human health. The World Health Organization estimated 282 million cases and 610,000 deaths in 2024—about 9 million more cases than the previous year.
Climate change, conflict, disrupted health systems, insecticide resistance and resistance to antimalarial drugs are making control more difficult in some regions. At the same time, decades of prevention and treatment have averted billions of malaria cases, showing that increases are not inevitable.
In the United States, researchers are particularly concerned about the expanding range of tick-borne parasites. Babesiosis, caused by a parasite that attacks red blood cells, was once concentrated mainly in parts of the Northeast and upper Midwest.
CDC researchers have documented rising case rates and geographic expansion into additional states. Longer tick seasons, expanding deer and tick populations, and land-use changes may all contribute to the increase.
Texas is confronting a different parasitic threat: the return of New World screwworm, a fly whose larvae enter wounds and feed on living tissue. The parasite had been eradicated from the United States for decades, but an outbreak that began in Central America spread through Mexico and reached Texas in June 2026.
Screwworm presents a serious danger to livestock, wildlife and pets. The risk to people is low but thousands of people in Central America have been infested with the flesh-eating maggots. Federal and state authorities are using surveillance, animal-movement controls and the release of sterile male flies to contain it but monitoring shows that screwworm is spreading.
Yet scientists caution against treating every parasite as ecologically disposable. Estimates vary, but research suggests about 40% of known species are parasitic, with many more undescribed. Parasites help regulate wildlife populations, move energy through food webs and indicate ecosystem change. Some are so specialized they may disappear when their host becomes extinct.
That creates a difficult contradiction. Public health programs must control parasites that threaten people, livestock and wildlife, while conservationists seek to understand, and sometimes preserve, species performing important ecological functions.
Guest:
Dino Martins is an entomologist and evolutionary biologist. His new book is "Hidden Creatures: Luscious Leaches, Bashful Botflies and the Wondrous History-Shaping World of Parasites."
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This interview will be recorded live on Tuesday, July 14, 2026, at 12:00 p.m.
