BIOLOGY Lecture Notes - Golden Pages 2003

10. MEDICAL PARASITOLOGY

Medical Arachnoentomology

It studies Representatives of the phylum Arthropoda, which comprises 1.5 million species. They are characterized by a chitinous exoskeleton and jointed appendages. The body consists of segments fused into three tagmata: the HEAD, Thorax, and abdomen. In certain groups, the head and thorax are fused into a single cephalothorax. Sensory Organs and mouthparts are located on the head. The Digestive System features complex glands. Depending on their lifestyle, the respiratory organs are book Lungs or tracheae. The Circulatory system is open, with the dorsal Heart. On the ventral side lies a nerve cord consisting of partially fused ganglia.

The classes Arachnida and Insecta are of medical importance. They include temporary and permanent parasites that serve as vectors and causative agents of infectious and parasitic diseases. Within the Class Crustacea, only a few species act as intermediate hosts for specific helminths.

Class Arachnida. Their representatives possess a cephalothorax and abdomen, along with six pairs of appendages: chelicerae, pedipalps, and 4 pairs of walking legs. Respiratory organs include book lungs and tracheae. Of medical importance are the order Scorpions, spiders (including venomous species), and the order Acari (mites and ticks).

Order Acari (Ticks and Mites). Representatives of this order have an unsegmented body. The mouthparts form a gnathosoma (or capitulum), which includes the chelicerae and an additional Structure called the hypostome. The pedipalps perform olfactory and tactile Functions.

The Development of ticks and mites proceeds through metamorphosis. A larva hatches from the egg, followed by a nymphal stage. The nymph then transforms into the adult stage, known as the imago.

Group 1. Ticks as temporary Blood-sucking parasites. This group includes ixodid ticks. Adult ticks feed on the blood of large livestock, dogs, foxes, and humans. The majority of these ticks undergo a three-host life cycle.

Ixodid ticks transmit the causative agents of dangerous diseases, such as spring-summer encephalitis.

Argasid ticks differ from ixodid ticks in The structure of their mouthparts. They can cause tick-borne spirochetosis (tick-borne relapsing fever).

The superfamily Gamasina (gamasid mites) comprises very small mites. They lead a predatory or ectoparasitic lifestyle. The bites of parasitic gamasid mites cause Skin lesions in humans in the form of dermatitis.

Several mites in this group are significant as vectors of certain viral and bacterial diseases.

Control measures against blood-sucking ticks are quite complex. The most rational approaches involve biological control Methods, such as utilizing organisms that parasitize ticks and their eggs.

There is another group of mites that inhabit human dwellings. These are very small animals, measuring less than 1 mm. They feed on food supplies, such as grain, flour, smoked meat, fish, mold spores, etc.

These mites pose a health hazard because they contaminate Food Products and can bite humans, causing grain itch and Various Forms of dermatitis. When ingested, these mites cause nausea, vomiting, and diarrhea. When inhaled with dust into the respiratory tract and lungs, they can cause respiratory acariasis.

House dust mites living in bedding, upholstered furniture, carpets, and mattresses contribute to allergic reactions and can trigger Bronchial Asthma.

Combating house mites involves wet cleaning of premises and The Use of upholstered furniture and pillows made of synthetic Materials.

Mites that are permanent human parasites include the itch mite (Sarcoptes scabiei), which is the CAUSATIVE AGENT OF Scabies in humans.