LU 4 Introduction to Medical Entomology

What is the definition of arthropods (Phylum Arthropoda)

A bilaterally symmetrical organism with chitinous exoskeleton and have jointed legs

What are arthropods consists of?

Insects (Class Insecta) & Arachnids (Class Arachnida)

What are the characteristics of insects (Class Insecta)?

• have three pair of legs

• have wings and antennae

• have compound eyes

• eg : ants, flies, fleas

What are the characteristics of arachnids (Class Arachnida)?

• have eight legs

• lack wings and antennae

• have simple eyes

• eg : scorpions, spider, ticks

What are the examples of arthropods / medically important arthropods?

• Class Insecta : Order Hemiptera (bugs) & Order Anoplura (lice)

• Class Arachnida : Order Araneae (spiders) & Order Scorpiones (scorpions)

What are the importance of insects and arachnids/ athropods?

1. Nuisance to human : cause bites and allergic reaction such as mosquito bites

2. Poisonous to human : can cause death such as black widow

3. Parasites of human : eg : screwworm

4. Vector of diseases : can transmit pathogens such as virus

What are the type of transmissions of insect-borne diseases?

1. Mechanical transmission : the pathogens utilize insects as vehicle for disease transmission

2. Biological transmission : the pathogens live inside the insects before they are transferred to another host

What are the types of biological transmission?

• Propagative (eg. viruses) organisms multiply in host

• Cyclopropagative (eg. Plasmodium sp. ) organisms need hosts for completion of life cycle: they develop and multiply in their hosts

• Cyclodevelopmental (eg. filarial worm) organisms need hosts for completion of life cycle and development, but do not multiply

What are the factors for successful transmission of insect-borne diseases?

• Longevity of insects

• Abundance of insects

• Biting habits of insects

• Susceptibility of insects to infection and ability to transmit it

What are the insects order that are medically important?

• Order Blattaria (cockroach)

• Order Siphonaptera (fleas)

• Order Anoplura (lice)

• Order Hemiptera (bedbugs)

• Order Diptera (mosquitoes & flies)

Explain about Order Blattaria (Cockroach)

• type of transmission

• life cycle

• prevention of infestations

• aid in mechanical transmission of viruses

• life cycle : undergoes incomplete metamorphosis (eggs,nymphs,adult)

• prevention of infestation: ensure house are clean, avoid leaving dirty dishes

Explain about Order Siphonaptera (fleas)

• their medically importance

• life cycle

• prevention of infestations

• is ectoparasites of human and animals

• they are nuisance because of blood feeding behaviour

• life cycle : eggs, larvae, adults

• prevention of infestation: ensuring pets are treated against fleas, house carpets must be vacuum frequently

Explain about Order Anoplura (lice)

• their medically importance

• life cycle

• body of lice is capable of vectoring pathogens

• life cycle : eggs, first,second,third stage larva, adult

Explain about Order Hemiptera (bedbugs)

• their medically importance

• life cycle

• prevention of infestation

• bedbugs are domestic pests and cause nuisance to human by their bloodsucking behavior.

• life cycle : egg, first,second,third,fourth,fifth stage of larvae, adult

• prevention of infestation : Insect spray, steaming

What are the symptom of head lice infestation?

• Itching

• A tickling feeling of something moving in the hair

• Irritability and sleeplessness

What are the prevention from head lice infestation?

• Do not share personal belongings

• Avoid head to head contact

What are the treatment for head lice?

• Pediculicides in the form of shampoo containing lindane

Explain about Order Diptera (mosquitoes and flies)?

• their medically importance

• genus of mosquitoes

• effects of flies

• Mosquitoes and flies are vector of pathogens such as viruses

• The most important genuses of mosquitoes are Anopheles, Aedes, Culex and Mansonia.

• Flies can cause myiasis (maggots)

What are the utilization of insects in medical field?

1. Maggot therapy

2. Forensics entomology

What is the meaning of these important terms in medical entomology?

• Vectors

• Pathogens

• Transmission

• Reservoir host

1. Vectors: agents responsible for transmitting disease causing organisms from one host to another.

2. Pathogens: the disease causing organisms (virus, protozoa, bacteria, nematodes)

3. Transmission: the transfer of pathogens from a host to another host by a vector.

4. Reservoir hosts (maintenance/amplifying hosts): animals or human harboring the disease-causing organisms (pathogens), but may not show any symptoms.