Invisible but found everywhere: How climate change is making mites, ticks bigger threat to human health

Mites and ticks are often mistaken for insects. Actually, they belong to the broader category of ‘arachnids’, creatures with two body segments and eight legs. They range from invisible dust mites in homes to blood-feeding ticks on pets and in forests, making them among the most widespread organisms on the planet.

While many species are harmless, others are parasites that cause diseases such as scabies, lumpy skin disease, and crop-damaging plant galls. Together, they impose a high cost on public health, livestock and agriculture. Scientists are now turning to genomics to better understand which species pose disease risk.

What researcher said?

A new genomic study led by Siddharth Kulkarni, a Ramanujan faculty member at the CSIR–Centre for Cellular and Molecular Biology (CCMB), Hyderabad, together with three undergraduate students from the Indian Institute of Science Education and Research (IISER), Thiruvananthapuram, sheds light on how parasitism in mites and ticks evolved over deep time. The findings could help improve disease surveillance and control, particularly as climate change alters the spread of vectors.

The research addresses a long-standing evolutionary question by tracing how parasitic traits emerged and diversified over more than 100 million years. The team analysed 90 arachnid genomes, the largest dataset of its kind, to reconstruct ancient relationships among mites, ticks and their relatives.

Instead of focusing only on individual genes, the researchers studied how genes are arranged on chromosomes. “Think of it like a deck of cards. Over millions of years, the cards (genes) get shuffled. But if you find two different groups of mites that have the exact same hand of cards in the same order, you know they share a common ancestor,” Dr Kulkarni explained.

The analysis indicated that mites and ticks belong to two separate evolutionary lineages that originated independently from separate ancestors: Acariformes (which includes most mites) and Parasitiformes (which includes ticks and the remaining mites).

Dr Kulkarni further added that the finding is a vital move toward reconstructing the evolutionary relationships among arachnids — from camel spiders to marine horseshoe crabs — whose group have long remained unclear. Finding these relationships can help scientists to predict the spread of known infections and identify potential new vectors before outbreaks take place.