The Real Bugs of Microbiology Identification and Overview of Medically Important Arthropods in the Microbiology Lab

What’s an Arthropod? A little review of organism taxonomy Any organism that belongs to the phylum Arthropoda which are characterized as an invertebrate with a segmented body, jointed appendages and chitinous exoskeleton.

There are two Classes of Arthropods that we primarily deal with: Class Insecta: 3 pairs of legs Have antennae Body is segmented in 3 parts Class Arachnida: 4 pairs of legs No antennae Body is segmented in 2 parts

Why are Microbiologist identifying arthropods? “We are the little “bug” people not entomologists!” Stacey H., “ bug hater” ~2007 But there are some good reasons why Microbiologists need to identify these organisms.

We are the infectious disease folks and arthropods are vectors (transmitters) of infectious diseases. Bacteria: Tularemia, Borrelia (Lyme disease), Plague Viruses: Colorado Tick Fever, Tick-borne Encephalitis Parasites: Babesiosis Transmission of Toxins: Tick Paralysis This is just to name a few

We are the “identification” folks We are the “identification” folks. We are accustomed to classifying organisms based on their characteristics. This is something we do everyday in the Micro lab with bacteria, fungi etc.

These are parasitic organisms and we like parasites These are parasitic organisms and we like parasites. Even if they do not transmit disease they still can cause harm or irritation to people.

Arthropods can be parasites? Parasite definition: An organism that takes something from another organism for existence without making a useful or adequate return. Arthropods are considered ectoparasites meaning parasites of the outside of the body.

The most common arthropods we identify in our Microbiology Laboratory.

Case One 15 year old male comes to the ED with headache, fever, chills, swollen lymph nodes and fatigue. He has a history of camping and hiking about a week ago.

Upon physical exam, the resident found this Upon physical exam, the resident found this. The organism was removed and sent to the Microbiology Lab

Once in the Microbiology lab, it was placed under a dissecting microscope. Identification?

Hard Ticks Ixodes, Dermacentor and Amblyomma

Characteristics of Hard Ticks Common Characteristics: Class Arachnida 5-6 mm in size 8 legs Disk-shaped body Prominent mouth parts

Characteristics of Hard Ticks cont. The things we look for to distinguish between the different Genus. The length of mouthparts (palpus and hypostome) The size/shape/color of the scutum Presence of festoons

Characteristics of Hard Ticks cont. There are three Genus of Hard ticks: Ixodes, Dermacenter and Amblyomma.

The Hard Tick Life “Questing for Hosts” They know a host is coming by vibrations and carbon dioxide. They will scale the plant and wave their legs in order to “catch” their host as they brush past. The tick will then walk around to find a “good spot” and then attach and feed.

The Hard Tick Life cont. They live in brush or wooded areas. They are sensitive to desiccation and temperature and will congregate in areas with high host animal traffic. Trails, roadsides and forest boundaries are areas that fulfill these requirements They will take about any mammalian host. Generally feed during the day

Most Common Hard Ticks in Colorado Rocky Mountain wood tick Dermacenter andersoni American dog tick Dermacenter variabilis

Medical Importance of Hard Ticks Hard ticks are great transmitters of disease Most common tick-borne diseases in Colorado Colorado Tick fever (virus) Lyme disease (bacteria) Relapsing fever (bacteria) Rocky Mountain spotted fever (bacteria) Tick paralysis (toxin) Tularemia (bacteria)

How are diseases transmitted? When a tick attaches itself to a host, it makes a cut into the skin and inserts a feeding tube. Also, it will secrete saliva that has anesthetic properties so that the host will not notice it. If a host animal has a pathogen, the tick will ingest these pathogens. The tick can then transmit that pathogen to the next host through the saliva.

Proper way to remove a tick Remove by using tweezers and grasping the arthropod close to the skin surface and pulling upward with steady, even pressure. Do not twist or jerk (you want to make sure the mouth parts do not stay behind). Never burn or traumatize the tick. This makes the tick regurgitate and increases the chances of disease transmission.

Case Two A 3 year old girl is brought to the CHC for her regular check-up. During the physical exam the physician noticed bites on the child. When asked, the parent said she also had bites and she thought that maybe they were mosquito bites.

Here is a picture of the bites noted on the child.

Before leaving this organim was found on the child’s stuffed bear Before leaving this organim was found on the child’s stuffed bear. The physician quickly scooped it up and sent it to Microbiology.

Once in the Microbiology lab, we placed it under a dissecting scope Once in the Microbiology lab, we placed it under a dissecting scope. Identification?

Bed Bugs Cimex lectularius

Characteristics of Bed Bugs Class Insecta About 5mm long Adults are reddish-brown in color, immatures are yellow-white Six Legs Pyramidal (triangle) shaped head Prominent compound eyes Slender antennae

The Bed Bug life They use heat and carbon dioxide to locate a host. They feed primarily at night. They tend to cluster on warm surfaces in cracks and crevices of wood, cloth, plaster. Easily travel from place to place in suitcases, clothing or other belongings. They have a worldwide distribution. Humans are their primary host

Medical Importance of Bed Bugs Though they have been suspected of transmitting disease in the past, recent studies have found no evidence that they have transmitted any human pathogen. The only real impact is that their bites can cause itching and inflammation.

Case Three 15 year old female patient comes to the ophthalmology clinic with complaints of eye irritation The physician noted the appearance of the patient’s eyelashes.

Several eyelashes were plucked and sent to the Microbiology Lab. This is what was seen under 40x Identification?

Eyelash Mite Demodex folliculorum

Characteristics of Demodex Class Arachnida 0.2 mm long 8 rudimentary legs Elongated and worm-like Transverse striations over much of their body.

The Demodex life They reside in our hair follicles and sebaceous glands. Contracted and spread by direct contact or dust containing their eggs. They consume the host epithelial cells. The “dandruff” commonly seen with infection is caused by the mite’s claws scrapping around the follicle.

Medical Importance They do not transmit disease but can cause symptoms of burning, crusting, irritation and redness of the eye.

Arthropods that are worth mentioning because they have medical importance but are not received in our Microbiology Laboratory for Identification (They are hard to catch in a urine cup)

Mosquitoes

The Mosquito Life Class Insecta Only female mosquitoes bite. A blood meal is required for egg lying. They are attracted to hosts by carbon dioxide or body chemicals. Once they have landed on a host, the mosquito inserts a proboscis and probes for blood vessels beneath the skin. Once a vessel is found it injects saliva into the wound. The saliva contains an anticoagulant for steady blood flow. If the host has a pathogen, the mosquito will ingest the pathogen. The mosquito will then transmit that pathogen to the next host via the saliva.

Medical Importance of Mosquitoes There are 3500 species of mosquitos worldwide. Only a small portion of these transmit disease but, the transmission and severity of disease caused by this small percentage is significant. Because of this, mosquitos are considered the #1 arthropod vector of disease. Each species has a particular ecology and geographical distribution. Disease transmission worldwide include: Malaria, Yellow fever, Dengue, filariasis, Zika, Chikungunya, West Nile, St. Louis encephalitis and Eastern Equine encephalomyelitis

Medical Importance cont. Worldwide Anapheles: Responsible for Malaria transmission Aedes: Responsible for Zika, Chikungunya Dengue and Yellow fever transmission

Medical Importance cont. In Colorado Culex: Responsible for transmission of West Nile, Western Equine, St. Luis and California encephalitis

Soft Ticks Ornithodoros and Carios spp.

Difference between Hard and Soft Ticks? Soft ticks have a wrinkled body with no scutum and the mouth parts are hidden underneath.

The Soft Tick Life Class Arachnida They generally feed at night. They do not stay attached to a host for very long. They live in animal burrows, dens, caves or huts, cabins or sheds. Known generally as Fowl ticks. Their preferred host are birds. Humans are accidental hosts.

Medical Importance of Soft Ticks The primary disease transmitted to humans is Relapsing fever.

Fleas

The Flea Life Class Insecta There are multiple species of Fleas. About every mammal group has its own flea including humans.

Medical Importance of Fleas In Colorado, we are most concerned with the Rock Squirrel flea (Diamanus montanus). This is a flea of squirrels, prairie dogs and other wild rodents. Humans are an accidental host. This flea is responsible for the transmission of plague.

Lice

The Lice Life Class Insecta Humans are the primary host Easily transmitted from person to person via clothing or belongings. Pediculus humanus capitis and corpis are the two species of human lice

Medical Importance of Lice Hair louse (Pediculus humanus capitis): Very common in school-age children worldwide. They do not transmit disease. Body louse (Pediculus humanus corpis): More common in third world countries with crowded living conditions. They do transmit diseases such as epidemic typhus, trench fever and relapsing fever.

If You Build an “Arthropod ID” test, they will Send you Anything and Everything

Unknown #1 What Class does this Arthropod belong to? Class Arachnida Common house Spider

Unknown #2 What Class does this Arthropod belong to? Class Insecta Cockroach

Unknown #3 My favorite submission for Arthropod ID Unknown #3 My favorite submission for Arthropod ID. Name this terrifying arthropod.

Thank You!