Parasitology

Parasitology

Study of Parasites
the study of non-mutual symbiotis relationships between species, where one species, the parasite, benefits at the expense of the other, the host

Ptotosoan infection

single cell parasite
some are intracellular
disease pathogenesis is variable

Helminth infection

multi-cell parasite: worm
pathogenesis → number of worms and patient immune response are related to severity of infection
large worm load
increased disability of host, such as immunocompromised individuals

Behavioral preventative measures

personal hygiene
proper sanitation
elimination of sexual activities involving fecal-oral contact

Chemoprophylactic agents

for malaria, such as chloroquine, mefloquine

Protozoans

sporozoana
amoeba
flagellates
ciliates

Helminths

nematodes
cestodes
trematodes

Sporozoans

Pasmodium
Toxoplasma

Plasmodium

causes malaria
febrile illness found throughout the world
transmitted by bite of Anopheles mosquito
Mortality: mainly in children, immunocompromised adults
Malaria is associated with a cycling of symptoms 

malarial paroxysm

continuous shaking and chills for 20-60 minutes followed by increased temperature with profuse sweating for 3-8 hours

Laboratory diagnosis of malaria

CBC with differential
Rapid antigen testing (Screening tests)
Thick and thin smears (these smears constitute confirmatory testing and if positive can be used to determine parasite load)

Toxoplasma gondii

obligate intracellular parasite

Toxoplasma gondii host

domestic cats

Toxoplasma gondii transmission

food/water borne
ingestion of food/water contaminated with cat feces
eating raw/undercooked meat containing cysts, such as pork, lamb, goat, beef, chicken
blood transfusion or organ transplant from infected donor

Toxoplasma gondii diseases

eye infection that can lead to vision loss
encephalitis/death
congenital toxoplasmosis (birth defects) in infants born to infected mothers

Toxoplasma gondii treatment

pyrimethamine, sulfonamides

Toxoplasma gondii infection

once infected, people are generaly infected for life

Ameoba

Entamoeba
Naegleria

Entamoeba histolytica

causes Amebiasis
an obligate intracellular parasite
passed from host to host as systs (form of parasite that survives environmental pressures such as chlorine, acid)
fecal-oral route of infection
ingestion of a single cyst can cause infection
the thir highest casue of parasitic deaths worldwide

Entamoeba histolytica symptoms

diarrhea
flatulence
cramping
abdominal pain
infection can last from months to years

Entamoeba histolytica treatment

blood and fluid replacement
admonistration of metronidazole
sanitary disposal of feces

Naegleria fowlerii

commonly referred to as “brain-eating ameba”
causes brain infection that is usually fatal → primary amebic meningoencephalitis (PAM)
commonly found in warm frech water
it survives best at higher temps up to 115°F
infections tend to be in summer month when people swim/dive in warm fresh water
people cannot get infected from swallowing water contaminated
contaminated water enters the body through the nose → travels to the brain
symptoms start 1-9 days nasal exposure
people dies 1-18 days after symptoms begin
PAM progressed so rapidly that diagnosis is usually made after death

Naegleria fowlerii diagnostic testing

CSF, biopsy, tissue specimens, molecular, immunology

Flagellates

Trichomonas
Giardia

Trichomonas vaginalis

Most commonly acquired, curable sexually transmitted disease in the USA
parasite can survive outside the host for 1-2 hours: in water, semen, urine, in can survive for 24 hours
Men and women who have this are at higher rick for getting/spreading other STD

Trichomonas vaginalis prevention

use condoms
seek medical attention if symptoms develop
notify recent sex partners so they can be treated also

Trichomonas vaginalis treatment

oral metronidazole cures 95% of cases

Trichomonas vaginalis women symptoms

itching or redness of the vaginal area
uncomfortable urination
the urge to urinate frequently
frothy, vaginal discharge that may be yellow or green in color
foul vaginal odor
swelling in the groin

Trichomonas vaginalis men symptoms

itching inside the penis
burning after urination or ejactulation
the urge to urinate frequently 
Penile discharge

Giardia lamblia

nonivasive
low morbidity rates
most commonly reported intestinal parasite in the USA

Cilates

Baflantidium

Baflantidium coli

rare in the USA
transmitted through the fecal-oral route
infection is mostly asymptomatic
symptoms include persisten diarrhea, abdominal pain, weight loss, vomiting, and sometimes perforated colon
when traveling to endemic tropical countries, infection can be prevented by following good hygiene practices

Nematodes: round worms

Enterobius vermicularis
Ascaris lumbricoides
Trichinella spiralis

Cestodes: tapeworms

Diphyllobothrium latum
Taenia saginatta
Taenia solium

Trematodes: flukes

Paragonimus westermani
Clonorchis sinensis
Schistosoma mansoni

Enterobius vermicularis

causes the intestinal infection, pinworm
Ubiquitous parasite of humans: mostly found in temperature climates
incidence: >200 million people infected annually, mostly children → nurseries, child care centers, orphanages

Enterobius vermicularis transmission

ingestion of eggs
stick to tissue, bedding, towels or fingers than can then be swallowed

Enterobius vermicularis symptoms

irritability, itching, skin abrasions from scratching

Enterobius vermicularis treatment

mebendazole, pyrantel pamoate

Enterobius vermicularis laboraroty diagnosis

Scotch tape Prep
adult female worm migrates out of the anus, usually at night, and deposits eggs on the perianal area
Eggas are not commonly found in feces, so stool is not an appropriate speciem for pinworm diagnosis
itching during the night in a child’s perianal area strongly suggests pinworm infection
Diagnosis is made by identifying the worm or eggs

Ascaris lumbricoides

causes ascariasis
most common intestinal nematode 
giant roundworm
occurs while egges are in the lungs are the intesine

Ascaris lumbricoides transmission

eggs are in soil, become dry and airborne - are then inhaled or swallowed 

Ascaris lumbricoides symptoms with prolonged infection of heavy worm load

fever, coughing, wheezing, shortness of breath
malnutrition, abdominal pain, obstruction of bile and pancreatic ducts

Ascaris lumbricoides treatment

albendazole, mebendazole, pyrantel pamoate

Ascaris lumbricoides symptoms

malnutrtion, discomfort, anemia, death on occasion

Trichinella spiralis

causes Trichinosis (roundworm)
disease is widespread among swine: human infection results from eating undercokked meat
most infections are asymptomatic

Trichinella spiralis symptoms

nausea, abdominal pain, diarrhea

Trichinella spiralis treatment

albendazole, mebendazole

Tapeworms

the largest of the intestinal parasites
lack vascular sytem, respiratory system, gut, body cavity
nutrients needed are absorbed by the host

Tapeworm symptoms

gastric dysfunction, nausea, diarrhea, weight loss

Tapeworm treatment

praziquantel niclosamie

Fish tape worm

diphyllobothrium latum

beef tapeworm

Taenia saginata

pork tapeworm

Taenia solium

Paragonimus westermani

lung fluke
incidence: 5 million infection worldwide

Paragonimus westermani transmission

consumption of raw or undercooked infected shell fish

Paragonimus westermani symptoms

diarrhea, fever, cough, urticaria, hepatosplenomegaly, pulmonary abnormalities, eosinophilia(acute stage), cough, expectoration of bloody sputun (hemoptysis), chest radiographic abnormalities (chronic stage)

Paragonimus westermani treatment

praziquantel, bithional 

Clonorchis sinensis

liver fluke

Clonorchis sinensis transmission

food-borne
human eats fish containing larvae
larvae are released into duodenum and ascend to common bile duct

Clonorchis sinensis symptoms

fever, chills, jaundice, eosinophilia

Clonorchis sinensis disease

low adult worm load is usually asymptomatic
high adult worm load can cause inflammation, fibrosis around bile duct

Clonorchis sinensis treatment

prasiquental, albendazole

Clonorchis sinensis prevention

cook fish adequately 

Schistosoma mansoni

blood fluck
incidence: 200 million people are infected globally

Schistosoma mansoni transmission

fecal-oral route

Schistosoma mansoni symptoms

caused by the body’s reation to the worms’ eggs
intestinal infection can result in abdominal pain, diarrhea and blood in the stool. liver enlargment is common in advanced cases - is associated with an accumulation of fluid in the peritoneal cavity and hypertension of the abdominal blood vessels. in such cases there may also be enlargment of the spleen
days after exposure: rash, itch skin
1-2 month post-infection: fever chills, muscle aches
infecion can persist for years

Schistosoma mansoni treatment

praziquatel

Schistosoma mansoni prevention

drink safe water
avoid swimming/wading in freshwater in countries known to have this parasite endemically
bathing water should be boiled and then cooled before use