Parasitology is the scientific study of parasites. Some parasitology studies evaluate the relationship between parasitic organisms and their hosts. Other studies look for and describe different types of parasites. Parasitology has applications in human and veterinary medicine. The study of parasites draws on other scientific disciplines, such as microbiology, organic chemistry, and cytology.
Though the name parasite has negative connotations, not all parasites adversely affect their hosts. In some cases, parasitology demonstrates how the relationship of a parasite to its host is mutually beneficial, called mutualism. The parasite and the host may gain protection from each other’s presence or provide each other with food. When parasite and host cannot exist apart, their relationship is called symbiotic. The two organisms are equally and mutually dependent upon each other.
Parasitology, when used in applications in human and veterinary medicines, tends to examine the relationship between parasites that invade and cause damage to the animal or human body. For example, insects that are vectors for disease are studied to see to what degree they pass those diseases on to humans or animals. The mosquito is a parasite that affects not only human populations, but also birds and horses. Some mosquitoes carry West Nile Virus, which in severe cases can result in encephalitis and sometimes death. In order to improve medicine’s understanding of West Nile Virus, parasitologists must understand the mosquito.
From past studies, parasitologists determined that not all mosquitoes are equally dangerous, and not all carry West Nile Virus. Only female mosquitoes bite, while male mosquitoes drink nectar. More recent parasitology studies have identified that mosquitoes that carry West Nile Virus have a tendency to survive and be present through winter in moderate climates. So from this, we know that the presence of a mosquito in December in the US means more risk to us of contracting West Nile Virus.
In veterinary medicine, parasitologists work specifically to eliminate flea infestation on cats and dogs. Recent technology has evolved to allow dogs or cats to either take a pill a month, or have a spot treatment on their back that either retards fleas from maturing, thus preventing bites, or directly kills fleas that bite. Some fleas can be vectors for diseases. Fleas on rats caused the Black Plague of the Middle Ages. Improved flea protection can minimize health risks and reduce flea infestation, providing relief to both pets and their owners.
Parasitology also studies the one-celled organisms that can make us ill, which can be either bacteria or fungi. Such studies depend on the ability to identify and describe cells, cytology, or microbiology at the microscopic level. Description of these cells and their presence has lead to better detection of certain bacterial and parasitic infections.
Parasitology must concentrate not only on identifying and describing harmful cells, but also on evolving methods for destroying them. From this information, medications are developed to treat specific infections. Understanding parasites led to the understanding of the role of antibiotics in treating bacterial infections, arguably one of the most significant medical developments in history.