medical entomology in brief
TRANSCRIPT
Medical Entomology in Brief
Dr. Alfatih Saifudinn Aljafari Assistant professor of Parasitology
College of Medicine- Al Jouf University
Aim and objectives
• Aim: – To bring attention to medical entomology as important
biomedical science
• Objective: – By the end of this presentation, audience could be
able to: • Understand the scope of Medical Entomology • Know medically important arthropods • Understand the basic of pathogen transmission dynamic •
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
In this presentation
• Introduction
• Classification of arthropods
• Examples of medical and public health important species
• Insect Ethology
• Dynamic of disease transmission
• Other application of entomology
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Definition
• Entomology: – The branch of zoology concerned with the study of insects.
• Medical Entomology: – Branch of Biomedical sciences concerned with “ArthrobodsIn the past
the term "insect" was more vague, and historically the definition of entomology included the study of terrestrial animals in other arthropod groups or other phyla, such, as arachnids, myriapods, earthworms, land snails, and slugs. This wider meaning may still be encountered in informal use.
• At some 1.3 million described species, insects account for more
than two-thirds of all known organisms, date back some 400 million years, and have many kinds of interactions with humans and other forms of life on earth
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Arthropods and Human
• Transmission of infectious agents
• Allergy
• Injury
• Inflammation
• Agricultural damage
• Termites
• Honey
• Silk
Medical Entomology in Brief- Dr. Aljafari
(CME- January 2019)
Phylum Arthropods
• Hard exoskeleton, segmented bodies, jointed appendages
• Nearly one million species identified so far, mostly insects
• The exoskeleton, or cuticle, is composed of chitin.
• Acute senses include simple and compound eyes, brains, and many ganglia.
• Arthropods use pheromones to communicate.
• They have open circulatory systems, complete digestive system, and efficient means of wastes excretion by Malpighian tubes.
• Arthropods reproduce sexually, but some exhibit parthenogenesis.
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
300 million years old fossil with full body impression
Insect perfectly preserved in amber
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Science for every insect
• Coleopterology - beetles • Dipterology - flies • Odonatology - dragonflies and damselflies • Hemipterology - true bugs • Isopterology - termites • Lepidopterology - moths and butterflies • Melittology (or Apiology) - bees • Myrmecology - ants • Orthopterology - grasshoppers, crickets, etc. • Trichopterology - caddis flies • Vespology - Social wasps
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Phylum: Arthropoda
Sub-Phylum: Chelicerata
Class: Arachnida/Octapoda; e.g., Spider, Mites and Ticks
Sub-Phylum: Mandibulata (Antennata)
Class: Crustacea; two pairs of antennae. e.g. Crayfish, Crabs, lobsters, shrimps
Class: Myriapoda
Sub-class: Chilopoda; e.g. Centipedes Sub-class: Diplopoda; e.g. Millipedes
Class: Insecta/Hexapoda
Sub-class: Apterygota (4 Orders) Sub-class: Pterygota (27 Orders)
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Class Arachnida
• A typical adult arachnid has two distinct body regions: Cephalothorax and abdomen. – Ticks and mites have only one body segment.
• Cephalothorax, bears 4 pairs of legs; a pair of chelicerae that are; a pair of pedipalps and simple eyes.
• They have no antennae and no wings. • large abdomen with no external gills or locomotor organs.
– Excretion by Malpighian tubules. – Respiration by book lungs and trachea.
• Spiders, mites, ticks, scorpions.
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Hottentotta tamulus Poisonous (neurotoxin)
Black widow (Latrodectus mactans) Poisonous
Sarcoptes scabiei -Lays its eggs in dermal layer -Severe itching - Causing (Sarcoptic mange) OR Scabies
Examples Arachinds of medically important for Human
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Bacterial
Lyme disease Borrelia burgdorferi Ixodes species
Relapsing fever Borrelia hermsii Ornithodoros species
Rocky Mountain spotted fever Rickettsia rickettsii Dermacentor variabilis
Viral
Tick-borne encephalitis (TBEV) Ixodes species
Protozoan
Babesiosis Babesia microti Ixodes species
Toxin
Tick paralysis Toxins Dermacentor andersoni
Ixodes species
Dermacentor Ornithodoros
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Class Crustacea
• Most crustaceans are aquatic and use gills for gas exchange.
• 2 pairs of antennae for sensing.
• Mandibles for crushing food that move side to side.
• Eyes are located on movable stalks.
• Many have five pairs of walking legs used for seizing prey and cleaning other appendages.
• First pair is often modified into strong claws.
Water flea (cyclops)
Transmission of Guinea warm (Dracunculus medinensis)
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Class Insecta
• A typical adult insect has three distinct body regions: head, thorax and abdomen.
• head, which bears one pair of compound eyes, one pair of unbranched antennae and paired mouthparts.
• the thorax, which is composed of three segments each bears a pair of legs, in many groups the second and third segments each bear a pair of wings.
• the abdomen, segments and having mating organ. – Excretion by Malpighian tubules; – respiration by pipe-like tracheae, exoskeleton or by gill; – digestion by tubular digestive tract; – blood circulation by open circulatory system; – reproduction by paired reproductive organs. – Muscular system, nervous systems also present.
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Subclasses of Insecta
• Apterygota – Wingless – One pair or more than one pair of appendages present in front
of genital opening – Mandible is attached into a specific position of head capsule – Moulting continuous after sexual maturity.
• Pterygota
– Winged or secondarily wingless insects – No appendage present in front of genital opening – Mandible is attached into two specific position of head capsule – Sexually matured adults do not moult.
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
English (common) Scientific Order عربي
Ant Hymenoptera النمل
Bee Hymenoptera النحل
Butterfly Lepidoptera الفراش
Grasshoppers Orthoptera الجراد
Fly Diptera الذباب
Mosquito Diptera البعوض
Louse (lice) Phthiraptera القمل
termite Isoptera دابة الأرض
spider Arachnida العنكبوت
There are more than 31 different orders of insects in the class Hexapoda, sixteen of which are considered of economic importance to agriculturists. Among them (according to Holly Quran)
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Phthiraptera
Diptera
Head Louse: -Transmission of Typhus
Siphonaptera
Rat flea (Xenopsylla cheopis) Transmission of Yersinia pestis Cause of Pleaque
Sand fly Transmission of Leishmania
Tsetse fly (Glossina) Treansmission of African Trypanosomiasis
Blackfly Transmission of Onchocerca volvulus The cause of (river blindness)
Deer fly (Crysops) Transmission of Loa loa Hemiptera
Tritomine bug (kissing bug) Transmission of American trypanosomiasis
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
• Chikungunya • Dengue fever • Lymphatic filariasis • Rift Valley fever • Yellow fever • Zika
• Malaria • Lymphatic filariasis
• Japanese encephalitis • Lymphatic filariasis • West Nile fever
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Ethology
• Circadian rhythm
• Feeding preference
• Host preference
• Ambience and humidity
• CO2 vs O: Female mosquitoes have nerve cells called cpA neurons that have a receptor to detect carbon dioxide.
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Vector-borne diseases
• Vector-borne diseases are human illnesses caused by parasites, viruses and bacteria that are transmitted by arthropods and snails.
• The major vector-borne diseases, together, account for around 17% of all infectious diseases
• Every year there are more than 700 000 deaths from diseases
Medical Entomology in Brief- Dr. Aljafari
(CME- January 2019)
Arboviruses
•Arthropod-borne viruses are viruses that can be
transmitted to man by arthropod vectors. The WHO
definition is as follows
•“Viruses maintained in nature principally, or to an important extent,
through biological transmission between susceptible vertebrate hosts by
haematophagus arthropods or through transovarian and possibly venereal
transmission in arthropods.”
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Dynamic of pathogen transmission
• Feeding habits: – Most of insect biological vectors are Heamtophagous
• Periodicity – Nocturnal – Diurnal – Sub periodic
• Host preferences: – Zoophilic – Anthopophilic – Zoonotic
• Type of transmission: – Biological – Mechanical – Vertical and transstadial
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Feeding habits: Most of insect biological vectors are Heamtophagous
Periodicity Nocturnal Diurnal Sub periodic
Host preferences: Zoophilic Anthopophilic Zoonotic
Type of transmission: Biological Mechanical Vertical and transstadial
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Dynamic of pathogen transmission
• Complex demographic, environmental and social factors. – Global travel and trade,
– unplanned urbanization and
– environmental challenges such as climate change • Changes in agricultural practices due to variation in temperature
and rainfall can affect the transmission of vector-borne diseases
– Factors affecting pathogen transmission, making transmission season longer or more intense or causing diseases to emerge in countries where they were previously unknown.
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
A. Africanus
A. bromeliae
Rural cycle
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Yellow fever transmission zone in Africa Aedes mosquito habitat
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Forensic entomology
• The scientific study of the invasion of the succession pattern of arthropods with their developmental stages of different species found on the decomposed cadavers during legal investigations
• Identification of insects at various stages of their life cycle, such as eggs, larva, and adults.
• Collection and preservation of insects as evidence.
• Determining an estimate for the postmortem interval or PMI (the time between death and the discovery of the body) using factors such as insect evidence, weather conditions, location and condition of the body, etc.
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Histerid beetles Predator of fly eggs
~ 10 days
Ham & Checkered Beetles (Cleridae)
Predator of flies & beetles;
also feed on dead tissue
~15 days
Skin Beetles (Dermestidae)
Feed on dried skin & tissues
~20 days
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Myiasis
• Myiasis is an infestation of the skin by developing larvae (maggots) of a variety of fly species within the arthropod order Diptera .
• Worldwide, the most common flies that cause the human infestation are:
– Dermatobia hominis (human botfly)
– and Cordylobia anthropophaga (tumbu fly).
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
Control and prevention
• Nets
• Insecticides
• Repellants
• Natural enemies
• Sterilization
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)
• Karl von Frisch
• winner of the 1973 Nobel Prize in Physiology or Medicine (ethology of bees)
Medical Entomology in Brief- Dr. Aljafari (CME- January 2019)