What disease can be caused by the protozoan Leptospira?

Leptospira is a genus of spirochete bacteria, not protozoan, that causes the disease known as leptospirosis. This condition is often contracted through contact with water contaminated with the urine of infected animals, particularly rodents and livestock. Symptoms of leptospirosis can range from mild flu-like symptoms to severe illness, which may involve liver damage, kidney failure, meningitis, or respiratory distress.

The other diseases listed are caused by different pathogens: malaria is transmitted by Plasmodium spp., lymphatic filariasis is caused by filarial nematodes, and giardiasis is caused by the protozoan Giardia lamblia. Understanding the specific causative agents of diseases helps in their diagnosis and treatment.