BIOL 4091 Exam 1 UNT Goven

Symbiosis

- relationship in which two species live closely together

- Vital for 1 out of the 2

Mutualism

A relationship between two species in which both species benefit

Commensalism

A relationship between two organisms in which one organism benefits and the other is unharmed

Parasitism

A relationship in which one organism lives on or in a host and harms it.

Infestation

To live "on" a host

Infection

- To live "in" a host

- Agent produces signs/symptoms

Facultative parasite

free-living but can become a parasite under harsh conditions (opportunistic)

Obligatory parasite

- a parasite that cannot live apart from its host

- "obligate"

- can form from facultative parasites

Endoparasites

live IN the body

Ectoparasites

live ON the body

Definitive host

host in which parasite reaches sexual maturity

ex: Humans

Intermediate host

host in which a parasite goes through the larval stage of development

ex: mosquitoes, snails, flies

Transfer host

not involved in the life cycle but needed to transfer to a new host

ex: flies, roaches

Vector hosts

Intermediate host that transmits disease

Reservoir hosts

Animal infected with parasite that serves as source of human infection

Exposure stage

in the presence of infectious agent

Colonization stage

having an infectious agent in or on you

Disease stage

Pathology/tissue damage

Signs stage is?

Precise

Incubation Period

Time period between initial infection and the first first signs and symptoms

Latency stage (infectious)

Time from being infectious to being transmitted into a disease

Parasite's utilization of host's food

They eat the host instead of the host's food

Parasite's destruction of host's tissue

- Blood feeders: Hookworms

- Lytic feeders: Liquifies tissue which causes pathology

Hookworm life cycle

1. Eggs enter soil via Human Feces

2. Eggs hatch as rhabditiform larvae

3. Revert into filariform larvae

4. Penetrates skin thru lesion

5. Larvae migrates thru bloodstream to lungs

6. Breaks thru lungs, causes them to be coughed up and swallowed

7. Larvae migrates to small intestines where they become infectious and revert to mature adult

Obstruction of lumens: Ascaris lumbricoides (giant round worm)

- Intestines

- Bile duct

- Pancreatic duct

Trickle infection

infecting yourself more and more a little at a time

What nematode exhibit trickle infections?

Ascaris lumbricoides

Does lumbricoides cause an immune response? Why/why not?

No bc they live in lumen

What disease can be caused by A. lumbricoides? Why?

Pancreatic and gallbladder disease because the worm is the same size as both ducts

What happens when A. lumbricoides experience an environmental change?

It doesn't like the change so it balls up and causes blockage in small intestine

What is an effect of A. lumbricoides causing a blockage in the small intestines? How is it cured?

Small intestine torsion (twist) which causes a lack of blood supply. It is fixed by surgery

Penetration of host's tissue: Entamoeba histolytica

Breaks thru gut and body wall

Where does Entamoeba histolytica live? What makes it a parasite?

Lives in the Large intestines. It slices tissue

What disease can be caused by histolytica? Why? What are the effects?

Peritonitis bc the parasite can eat thru the large intestines and seep out into the liver. This causes dysentery (blood in the stool)

What happens in the stimulation of host tissues thru eosinophilia?

increased number of eosinophils

What are the normal levels of eosinophils vs when an infection is present?

Normal: 0-4%

Infection: about 25%

What happens in the stimulation of host tissues thru erythropoiesis?

Increase in the production of red blood cells

What happens in the stimulation of host tissues thru neoplasia?

Cancer of tissues

What are carcinomas?

cancers of the epithelial tissue

Parasite density and distribution

Flora: Vegetation

Fauna: Animals

Water: important bc it promotes diversity

What is biotic potential?

The maximum rate at which a population of parasites could increase under ideal conditions

How many eggs does an Ascaris female lay a day?

200,000 per day

Life cycle of Entamoeba histolytica

cysts in feces --> humans ingest mature cysts via fecal contaminated food, water, hands --> cysts matures in small intestine and migrate to large intestine --> multiply via binary fission, produce cysts and trophozoites --> cysts passed feces (can survive external environment for a couple weeks); reside in lumen --> carriers pass cysts in feces

What are helminths? What are the three types?

Helminths are worms

Nematodes- Round worm

Cestodes- Tapeworm

Trematodes- Flukes

Where do helminths get their nutrition and live once inside of a host? How do they enter its host?

Blood and tissue- more pathological

Intestinal

By "picking it up"

What type of digestive tract do helminths have? Do they have separate sexes or are they asexual?

Complete digestive tract (Mouth and anus)

Have males and females

What are the 4 types of protozoans?

Amoeba

Ciliates

Flagellates

Malaria- sporozoites

Where do protozoa get their nutrition and live once inside of a host? How do they cause infection?

Blood and tissue

Intestines

"one divides"- most pathogenic

What helminth is infective in the Egg stage?

Enterobius vermicularis- Pinworm

Trichuris trichiura- Whipworm

Ascaris lumbricoides- Giant roundworm

Normal Life cycle of Enterobius vermicularis

1. Egg ingested thru contaminated fingers

2. Larvae hatch in small intestine and migrate to colon

3. Larvae mature into adults and migrate out of anus at night

4. Adult female lay eggs on perineum (around anus), males die after mating

5. Eggs embryonate on perineum, female dies after birth which causes itching sensation

6. L.C. starts over

Anormal life cycle of Enterobius vermicularis (path 1)

Migration into vagina --> uterus --> fallopian tubes --> worm ruptures causing tissue damage, leaves behind eggs and debris --> causes inflammation/infiltration --> scar tissue/inflammation

Anormal life cycle of Enterobius vermicularis (path 2)

Migration into vagina --> uterus --> inflammation/scar tissue --> infiltration --> tissue damage --> worm ruptures causing tissue damage, leaves behind eggs and debris

What is the epidemiology of Enterobius vermicularis?

- Group infections: primary/kindergarten

- Transmission: direct; anus to mouth via fingers

indirect; air borne eggs > nasal cavity or via fomites ("inanimate objects" i.e. crayons, doorknobs) [fomite > hand > mouth]

- Colder climates: most common in these areas; common is warm areas

What is the pathology and clinical manifestations of Enterobius vermicularis?

- Large intestines: where they feed on mucosa

- Appendix

- Toxic metabolites

- Perianal area

- Vagina

How is Enterobius vermicularis diagnosed?

- Itching/scratching perineum

- Anal swab w/ Q tip

- Scotch tape test

- Preserve worms in alcohol, vodka, gin, or vinegar

- See female worm in stool

What disease can be caused by Enterobius vermicularis?

appendcitis

What characteristic does pinworms have that confirms its identity?

Cephalic swelling

How do you treat Enterobium vermicularis?

Albendazole

What are the effects of Albendazole?

Affects the worm's digestive system which decreases it's glucose uptake, causing it to have no energy and essentially starving the worm to death

How do you prevent contracting Enterobium vermiularis?

- Mass chemotherapy: Albenazole and treating whole class

- Personal hygiene: washing hands

- Detergent/Clorox: kills eggs

- Sunlight/UV light: kills eggs

Pinworms are vile for weeks

Life cycle of Trichuris trichiura

1. Unembryonated egg passed in feces

2. Embryonated egg ingested

3. Larvae hatches in small intestines

4. Mature into adult and mate in cecum

Characteristic of Trichuris trichiura egg

Mucus plug

What is the epidemiology of Trichuris trichiura?

- Loves warm temps (70-80degrees), moist areas (rain) and shaded soil

- Most common in Southeastern US (20-25%) and parts of Asia (50-80%)

- Associated with night soil (human feces furtilizer)

Female and Male Trichuris trichiura

What is the pathology and clinical manifestations of Trichuris trichiura?

- Mainly in the rectum

- Large intestine: attaches/sews self to gut wall and feeds on it

- Results in low infection: tissue injury, 2ndary infection, hemorrhage, pain, and loss of appetite

- Results in heavy infection: Anemia, dysentery, fever, rectal prolapse, and bacterial infection

How is Thrichuris trichiura diagnosed?

- Proctoscopic exam

- Colonoscopy

- Eggs in stool

- Eggs barrel shaped

- Fecal smear

- Imaging

How do you treat Trichuris trichiura?

Mebendazole- same effects as pinworm treatment

How to prevent Trichuris trichiura?

- Sanitary disposal of feces/night soil

- Personal hygiene i.e. washing hands/food

Life cycle of Ascaris lumbricoides

1. Egg is ingested

2. stomach acid weakens shell

3. Eggs hatch in small intestine

4. Female lays eggs in small intestine but not all are fertilized (those are deposited in stool)

5. Larvae migrate to lungs where they are then coughed up and swallowed

Ascaris lumbricoides egg characteristics and "need to know"

- Thick, rigid outer shell made of protein (cortex)

- Extremely resistant to heat, disinfecting agents

- Looks like debris when examining feces

- Can cause allergic reaction if reinfection is continuous

Female and Male Ascaris lumbricoides

Females are always bigger than males

What is the epidemiology of Ascaris lumbricoides?

- Very common: 1.2 billion infected world wide, once you have it you have it forever

- Regions with high infection rate: Southeastern US (bc of weather conditions are favorable), Central/S America, and Asia/China

What is the pathology and clinical manifestations of Ascaris lumbricoides?

- Lungs: petechial hemorrhage (little well defined red spots produced in larval stage), sero-cellular exudate (sero-: fluid), cough, and allergic reaction to molting fluid (produced once worm molts into adult, it increases hydrostatic pressure)

- Small intestines: Resides in lumen of gut (no pathology/tissue invasion) and swims against peristaltic movement of gut

-Abnormal/Dangerous Outcomes: Intestinal obstruction (due to change in environment), appendicitis (bacterial infection 2ndary to worm damage), Abnormal migrations (i.e. pancreatic/bile duct, esophagus, mouth, ears, nose/sinus), trachea/lungs, gut penetration (small intestine; rare but happens)

How is Ascaris lumbricoides diagnosed?

- Eggs in feces

- Fecal smear

How is Ascaris lumbricoides treated?

Albendazole, it is recommended that the person fast for 24hrs so that the medicine is more available to the worm

How is Ascaris lumbricoides prevented?

- Sanitation when disposing night soil

- Wash food

- Personal hygiene i.e. washing hands

What intestinal nematodes are infective in the larval stage?

Necator americanus- New World Hookworm

Ancylostoma duodenale- Old World Hookworm

Ancylostoma canium- Dog hookworm

Ancylostoma braziliensis- Cat hookworm

How many eggs can Necator americanus and Ancylostoma duodenale lay per day?

Necator americanus: 5-10,000 eggs/day

Ancylostoma duodenale: 10-20,000 eggs/day

What type of oral cavity does Necator americanus have?

Lunar cutting plates

What type of oral cavity does Ancylostoma duodenale have?

Fangs/chitinous teeth plates

Life cycle of Necator americanus and Ancylostoma duodenale (hookworms)

1. Eggs deposited in feces

2. Larvae hatch as rhabditiform larvae

3. Molts into filariform larvae

4. Filariform larvae penetrates skin

5. Mature into adults in small intestine

What is the epidemiology of Necator americanus and Ancylostoma duodenale?

- Both found in Southeastern US and (sub)tropics/tempered zones

- Favors warm temperatures and rainfall

- Susceptible to all ages (crawling+)

- Frost/cold weather= larval fatality

What is the pathology and clinical manifestations of Necator americanus and Ancylostoma duodenale?

- Larval penetration of Skin: Lesion (wound/tissue damage), papule (hard red bump/inflammation), vesicle (fluid filled capsle/white head), puritis, edema, erythema, repeated infection can cause allergic reaction (ground itch)

- Larval migration: Circulation (larvae enters thru skin and "breaks out" thru capillaries in lungs), Lungs (petechial hemorrhage), Intestine (larvae is coughed up, swallowed, and migrate to small intestine where they mature into adults/begin to feed causing (re)attachment damage)

- Anemia: Both hookworms suck a total of .1 mL blood/day/worm

- Iron deficiency: "pica" (urge to eat dirt)

- Mental and physical stunted due to anemia: result of long term lack of oxygen do to lesions from feeding patterns, could cause retardation

- Morbidity: negative overall health

Male hookworm

Female hookworm

Hookworm egg

How is the presence of hookworms diagnosed?

Eggs in stool and low blood count

How are hookworms treated?

Mebendazole/Albendazole

- Reinfection is up to 80% in 36 mo do to people not changing the way they live

How are hookworms prevented?

- Wearing shoes

- Sanitation and disposal of feces

- Proper treatment of night soil

- Personal hygiene

- Clorox solutions

Are Ancylostoma canium/braziliensis infectious to humans? What does it cause?

- Partially, instead they migrate subcutaneously known as the serpiginous tunnel. The parasite's life cycle cannot be completed since they are in the wrong host.

- Puritis, inflammation, 2ndary bacterial infection, possible loss of toes, and hypersensitivity/allergic reaction

What is the pathology and clinical manifestations of Ancylostoma canium/braziliensis?

- Early lesion: edema and inflammation

- Late lesion: puritis, scab forms, crusty covering

- Pathology done due to immune response to serpiginous tunnel

How is Ancylostoma canium/braziliensis diagnosed?

Thru observation of the animal and the presence of serpiginous tunnels

How is Ancylostoma canium/braziliensis treated?

Thiabendazole cream

How is Ancylostoma canium/braziliensis prevented?

- Don't allow pets in sandboxes/on the beach

- Take care when working/playing around animal quarters

- Use plastic drop cloth when in crawl spaces under houses

- Properly dispose dog feces

Life cycle of Trichinella spiralis

1. Ingest undercooked/infected meat

2. Larva released in small intestines after digesting meat

3. Mature into adults in small intestine where they mate

4. Larva deposited in mucosa via circulatory system

5. Larva curl up, forming cyst in muscle and become dormant

What are some example locations where Trichinella spiralis larva may reside?

- Eye muscle

- Diaphragm

- Larynx

- Tongue

- Intercostal/Breathing Muscles

- Biceps/triceps

- Pectorals

Favors well oxygenated muscles

What is the epidemiology of Trichinella spiralis

- Maintenance cycle: rodent cycle

Pig-pig

Rat-rat (can be spread to pig cycle)

Rat-pig (can be spread to human)

Wild boar

Bear

- Control infections by: Freezing meat (18degreesF) and cooking meat @ 310degreesF for 35min per lb

Why is Trichinella spiralis considered the "great imitator"?

It's signs and symptoms resembles a lot of other illnesses i.e. cold/flu

What happens in the 1st stage of infection for Trichinella spiralis? Symptoms?

- 1 to 10 days post infection

- Ingestion of larvae mature into adults in small intestines

- Necrosis and panmucosal inflammation begins @ 72 hrs and peaks @ 8 days

- Symptoms: Nausea, vomiting, diarrhea, fever

Very important stage

What happens in the 2nd stage of infection for Trichinella spiralis? Symptoms?

- Overlaps with stage 1: 7 to 14 days post infection

- Adults expelled from intestines (self cure; larval migration)

- Larvae migrate from gut to muscles via circulatory system (BV)

- Symptoms: lung hemorrhage from larvae rupturing capillaries, ocular edema as they invade eye muscles (first sign), and hyper eosinophilia (as high as 25%)