Parasites, Mycology, Vector Borne, Public Health Infections Flashcards
What are characteristics of a vector borne illness
Transmission by live agents
Potential for rare transmission by other routes
Areas of endemicity restricted by vector
Control of vector may allow control of disease
What are some vector borne illnesses of concern in Nova Scotia
Lyme
Anaplasma found not diagnosed
Babesia found but not diagnosed
Describe ixodes scapularis
Vector often referred to as the black legged tick
Found in southern maritimes and southern Canada
Requires blood meal at each stage of maturation in females meaning females do most of the biting
Describe Lyme disease
First described in Lyme Connecticut
Caused by Borrelia Burgdorferi A GRAM NEGATIVE SPIROCHETE
transmitted by ixodes ticks
Describe the tick involvement in Lyme
Antigenic changes occur when a tick bites a host, 24-36 hours of attachment needed for transmission
Nymphs and adults are stages of tick involved in transmission
How does Lyme clinically present itself
Early localized disease (3-30 days post bite) = bullseye rash (erythema migrans) , flu like illness
Early disseminated disease = EM lesions, neurological or cardiac disease
Late disease = arthritis esp knee some neurological symptoms maybe
How is Lyme diagnosed
Early localized disease diagnosed clinically
Serology positive after a few weeks (IgM/IgG)
2 sub sequential rapid tests used more now but used to use enzyme immuno assay/western blot
How is Lyme treated
Prophylaxis (doxycycline)
Early disease: amoxicillin, doxycycline or cefuromine given for 3 weeks
Neurological disease (not palsy) = cefrtriaxone, penicillin or doxycycline for 28 days
Late Lyme may persist post treatment
Describe Babesiosis
An apicomplexa parasite related to malaria
Transmitted by ticks
Mice act as reservoir
24-36 hours of attachment for transmission
Lives in red blood cells within humans
What does Babesiosis do
Causes anemia, fever and hemolysis
More severe disease can occur if no spleen, old, v young or immunosuppressed
How is babesiosis diagnosed
Blood smear most common
Detection of parasite DNA by PCR if seen in blood (sensitive)
Serology for screening blood
How is Babesiosis treated
Antimicrobials are very effective
Describe anaplasma
Grows inside phagocytes Transmitted by ixodes ticks GRAM NEGATIVE OBLIGATE INTRACELLULAR bacteria Occurs summer/early fall Incidence of disease increases by age
Where does anaplasma infect
Granulocytes (pus cells) and grows in their cytoplasm
Must grow inside cells as it is unable to survive outside of cells due to being unable to produce peptidoglycan
What are symptoms of anaplasma
Fever, headache, muscle aches, malaise, cough, abdominal pain
How is anaplasma detected
NAAT for early illness although early illness rare
Inclusions in granulocytes
Serology mainly !
How is Anaplasma treated
Doxycycline for all ages and tick avoidance
Describe Q fever
Coxiella burnetii
SMALL GRAM NEGATIVE RODS INTRACELLULAR PATHOGENS
Large actively growing form and small dormant form
Pathogen of goats, sheep, cattle and cats
Transmitted by aerosols and rarely ticks
How does Q fever present
Flu like with fever (common) Pneumonia (common) Hepatitis Chronic infection (endocarditis usually) Pregnancy complications
How is Q fever diagnosed
Serology
How is Q fever treated?
Doxycycline and trimethoprim sulfamethoxazole
Who described Rocky Mountain spotted fever
Dr Howard Taylor Ricketts described the agent
Initially referred to as black measles
Describe Rocky Mountain spotted fever
Rickettsia rickettsii tiny gram negative intracellular bacteria
Infection in ticks- act as reservoir and vector (dog tick)
Infection transmitted between ticks by trans ovarian route (from birth) and sexually
How does Rocky Mountain Spotted Fever present
Flu like illness, headache, myalgia
Abdominal/joint pain, diarrhea, cutaneous gangrene
Rash 3-5 days post fever becoming raised and papular does not spare palms and soles
May be fatal is G6PD deficiency
How is Rocky Mountain spotted fever diagnosed
Low platelets, low sodium, liver enzymes increased, WBC normal
Diagnosis slow
Serological diagnosis using IFA
Describe tularaemia
Francisella Tularensis small GRAM NEGATIVe COCCOBACILLUS
Infection of wild hare/rabbit/rodents
Transmitted by ticks and biting flies
May also be acquired from handling dead carcasses or inhaling dust
How does Tularemia present
Papule at site of inoculation forms tender ulcer and scab
Painful lymphadenopathy, fever, headache, cough
Lasts several weeks
May progress to sepsis, pneumonia or meningitis
How is Tularemia diagnosed
Culture from blood or discharge
Immunofluoresce, PCR or serology after recovery
How is Tularemia treated
Streptomycin and doxycycline
What makes an infection of public health significance
Potential to rapidly spread
Associated with mortality and morbidity
Panic and concern
Can be controlled by strict guidelines
Describe West Nile Virus
Caused by member of the flavivirus genus (enveloped positive sense single stranded RNA virus); and arbovirus
Birds are natural hosts, transmitted by mosquitoes
How does West Nile virus present ?
Fever, aches, pains, malaise, 50% have a rash
Most severe progress to meningitis, encephalitis, paralysis or other neurological conditions
Can be passed vertically
How is West Nile virus detected
Diagnosis usually by serology either IgM or rising IgG titres
Describe encephalitis
Inflammation of brain tissue
Fever, headache, vomiting, confusion, coma or death
Arboviruses such as WNV can cause encephalitis
Diagnosed by serology
Describe Dengue
Member of flavivirus genus which is a positive sense single stranded RNA virus
Widely endemic in the tropic
What happens when reinfection of new Serotype of Dengue fever occurs
Reinfection with a new sero type may cause severe dengue hemorrhagic fever
How does Dengue present?
Usually minimal symptoms
2-7 days of high fever, myalgia, arthralgia (break bone fever), macular-papular rash
Describe dengue hemorrhagic fever
After initial phase of fever patient develops plasma leak and bleeding lasts about 1-2 days but very life threatening
Followed by convalescent phase and recovery may develop rash
How is dengue treated
Supportive treatment, fluid replacement and IV fluid volume support for hemorrhagic fever
Prevention most important
Vaccine available IF previously infected
Describe yellow fever
Flavivirus transmitted by aedes asgypti (mosquitos)
Usually in tropics, Africa and South America
Primarily monkey-mosquito with human spread
How does yellow fever present
3-6 day incubation
Fever, flu like illness with vomiting then recover
1/7 develop jaundice bleeding and shock (high risk of death)
How is yellow fever diagnosed
Serology most useful but can cross react with other flaviviruses
How is yellow fever treated
Supportive but avoid aspirin as it thins the blood
Prevention most important vaccine available
Describe Zika Virus
Flavivirus
RNA virus arbovirus group
Found in many popular winter destinations
How does Zika present
Relatively mild: fever, rash, conjunctivitis and muscle pain
Major risk is birth defects especially microcephaly or guillian barre syndrome
How is Zika transmitted
Mosquitoes but also sexual contact for 6 months after acute infection
How is Zika diagnosed
NAAT for first 14 days in serum or urine
Serology after 14 days
How is Zika treated
No treatment or vaccine mosquito avoidance and condoms best route
Describe the plague
Yersinia Pestis a member of enterobacteriaceae
Spread by fleas, natural hosts are rodents esp rats
High death rate
What are the two types of the plague
Bubonic (flea transmitted)
Pneumonic (person to person transmitted)
Describe bubonic plague symptoms
Painful enlarged lymph nodes (buboes) with headache, malaise, flu like illness progresses to sepsis and disseminated intravascular coagulation and death
Describe pneumonic plague
Results in very aggressive pneumonia that progresses to sepsis and death
How is plague diagnosed
Culture of blood, discharge of bubo, sputum
How is the plague treated
Streptomycin or doxycycline
Describe Ebola
Filoviruses cause life threatening Hemorrhagic fever
High mortality
How is Ebola diagnosed
Detection of viral nucleic acid
How is Ebola treated
Supportive
Canadian made vaccine also seems effective
How does Ebola present
Headache, lack of energy, fever, sore throat, muscle ache: progresses to vomiting blood and diarrhea then bleeding from all orifices and internal bleeding
Describe rabies
Caused by lyssa virus a negative single stranded RNA virus (looks like a bullet)
Transmitted from bite or scratch containing saliva from infected animal
1-2 month incubation period unless face affected
What are symptoms of rabies
Pain at injury site, headache, Malaise, seizures, hallucinations, disorientation, coma and death as well as hydrophobia
How is rabies prevented
Wash wound, rabies immune globulin, anti rabies vaccine (4 doses over 1 month)
Generally effective prior to symptoms
Describe diphtheria
Occurs when immunization rates fall
Person to person transmission through droplets or skin contact
How does diphtheria present
Pharyngitis with greyish membrane
Cutaneous in skin ulcers
Describe tetanus
Caused by clostridium tetani anaerobic gram positive rods produces spores
Mediated by tetanus neurotoxin arising from wound infection
Toxins inhibit CNS inhibition of peripheral nerves at the spine
How does tetanus present
Difficulty swallowing, right jaw muscles, prolonged muscular spasms
How is tetanus treated
Wound cleaning, penicillin and tetanus antitoxin
Describe neonatal tetanus
Can be deadly
Associated with contamination of the umbilical cord after birth
What is a fungus
Eukaryotic Larger and more complex that bacteria Has a cell wall Lack chlorophyll Reproduce sexually and asexually Biochemically distinct pathways
What is present in a fungi cell wall
Ergosterol which is what antifungals usually target
Describe yeast
Single cellsd
Elongate to form chains of cells (pseudohyphae)
Reproduce by budding to form daughter cells or blastospores
Some are commensal
Describe moulds
Multicellular
Form tubular structures which may have cross walls or not
Many hyphae form a mycelium
Produce asexual spores
What are dimorphism fungi
Fungi behaving as yeasts or moulds
Grow as mould at room temperature
Grow as yeast in elevated temperature
Geographically limited in distribution
How do fungi cause disease
Growth on body surfaces
invasions of the body
Allergic reaction
Toxins upon ingestion
What causes yeast infections
Candida albicans
Often commensal on mucus membranes in GI tract rapidly colonizes damaged skin
Describe candida species
Candida means white
Gram negative
Commensal on skin, mucus membranes and in the environment
What are examples of mucocutaneous yeast infections
Oral (thrush, stomatis, chelitis)
Vaginal
GI tract
What is chelitis
Mucocutaneous yeast infection
Angular erosions on mouth with pustules
What are skin and nail yeast infections
Intertrigo (damp areas)
Diaper rash (poor hygiene)
Nail frequent immersion in water
What are dermatophytes
Closely related to keratolytic fungi
Minor trauma allows for initial infection
Occlusion allows for infection as well as moisture
Ringworm athletes foot or jock itch
How do dermatophyte infections present and transmit
Red, scaly rash May have pustules
Transmitted via skin squames containing fomites (combs) rarely direct contact
How are dermatophyte infections diagnosed
Skin scrapings, nail clippings, hair
Microscopy
Culture
Dermatophytes are not part of normal flora infection present if they are present
Describe tinea versicolor
Superficial skin infection caused by Malassezia Furfur
Common cause of skin infection in healthy people
Flourishing on skin fatty acids
How does tinea versicolor present
Manifests as hyper or hypo pigmented lesions with itching and occasional pustules
How is tinea versicolour diagnosed
Clinically
Skin scrapings
Microscopy shows spaghetti and meatballs pattern
Cannnot culture as it only grows with oil supplement
Describe invasive fungal infections
Divided into 2 groups
- Opportunistic (occur widely)
- Geographically defined
What are examples of systemic yeast infections
UTI (catheter)
Endocarditis (prosthetic heart valves)
Septicaemia (immuno compromised)
How are invasive yeast infections diagnosed
Clinical suspicion Microscopy Culture (several days) Antigen detection Imaging
How are invasive yeast infections treated
FLYCONAZOLE
Superficial infections may be treated with nystatin
Describe cryptococcus
Cryptococcus neoformans is an encapsulated yeast
Causes pneumonia can cause meningitis
Found in Vancouver less likely elsewhere in Canada
Describe pneumocystis jirovecii
Non culturable yeast (no budding!!)
Causes pneumonia in immunosuppressed
Diagnosed by immuno fluorescence NAAT and silver stains
Describe Aspergillus Spp.
Main mould that causes infection
Grows on rotting vegetation
Spores present in outdoor air
Immunosuppressed most at risk
How does Aspergillus infections present
Allergies to spores leading to asthma
Bronchopulmonary aspergillosis
Fungal ball in cavities
How is Aspergillus Infection diagnosed
Microscopic: KOH
Culture
Describe Histoplasma Capsulatum
Dimorphic fungi
Found in central US
Infection occurs when spores inhaled and germinates in the lung
Only small proportion infected develop disease
Describe parasites
Eukaryotic Distinct from fungi No chlorophyll Single celled to multicellular Microscopic to macroscopic
Describe Protozoa
Based on means of locomotion
Amoebae form cytoplasmic protrusions in order to love and change shape (pseudopodia)
Occur as trophizoites (active and growing) and cyst (environmentally protected)
Describe entamoeba histolytica
An enteric amoeba
Ranges from asymptomatic to dysentery and liver disease
Transmitted fecal/oral
Identical non pathogenic species called entamoeba dispar
Describe environmental amoebae
Found in natural surface water
Can cause corneal infection in contact lens wearers (chronic ulcers)
May cause amebic meningoencephalitis
What are flagellates
Propelled by flagella
May occur in two forms: trophozites (active) cyst (dormant)
Rigid outer wall
May cause gut infection
Describe Giardia
Enteric flagellate
Ranges from asymptomatic to acute or chronic diarrhea
Fecal oral or waterborne tranmission
Diagnosed by microscopy of stool
Describe Trichinoniasis
Flagellate infection
Causes vaginitis
Sexual transmission usually from males
Diagnosed by microscopy of discharge or culture
Non pathogenic found in oral cavity and gut
Describe Trypanosomiasis
Africa
Found in AFRICA Systemic flagellate infection Sleeping sickness (fever encephalitis) Transmitted by TSE TSE fly Detection: parasites on blood smears and serology
Describe trypanosomiasis (South America)
Chagas’ disease (cardiac complications)
Transmitted by Reduvid Bug
Detected by parasites stained on blood smears and serology
Describe Leishmaniasis
Systemic Flagellate
Present as cutaneous ulcers or visceral infiltration and Hepatosplenomegaly (enlarged liver and spleen)
Describe Apicomplexa
Mature forms non motile
Complex life cycles
Attach
Cause malaria
Describe Malaria
Apicomplexa Plasmodium Spp. episodic fevers and anaemia Transmitted by mosquito bites Detected by parasites stained on blood film
Describe Cryptosporidium spp
An enteric apicomplexa
Watery diarrhea (chronic in immunosuppressed)
Fecal oral, waterborne, zoonosis tranmission
Detection by microscopy of stool using acid fast stain or detection of antigen in stool using EIA
Describe cyclospora
Looks like cryptosporidium but 2X bigger
Watery diarrhea
Fecal oral route especially in tropics
Detection by microscopy
Describe toxoplasma Gondi
Apicomplexa causing systemic disease
Mostly asymptomatic unless pregnant (fetal malformation)
Transmitted by poorly cooked meat and cat stool
Detected by serology
Describe Helminths Platyheminths
Bigger organisms
Flatworms
Describe cestodes
Tapeworms Ribbon like and segmented Largest is 10m Hermaphordite (ovaries and testes) No digestive system Adult attaches to gut using scolex (hooks or suckers) Larval forms in tissues (cysts)
Describe the life cycle of Cestodes
Definitive host gut contains adult worm
Environment where ova are consumed by intermediate host in whose tissue the larval stage develops
When intermediate host is eaten by definitive host adult worm develops in gut and later produces ova
Describe taenia saginata and taenia solium
Beef and pork tapeworm
Principle cestode pathogen
Abdominal discomfort
Transmitted by larval forms ingested in food
Detected by identification of ova or adult segments in stool
Describe Cysticercosis
T. Solium larvae
Cysts throughout the body including brain
Transmitted by ingested ova
Detected by serology, X-ray, ultrasound etc
Describe Trematodes
Flukes (kinda like flatworms)
Leaf shaped, hermaphrodite, primative gut, suckers for attachment
Definitive host life cycle
Ova (environment) consumed by intemredjate host and ova becomes larva
Describe schistosomiasis
Effects of inflammation, hematuria (blood in urine)
Transmitted by penetration of skin in fresh water
Detected by ova in stool/urine
Describe Nematodes
Roundworms Big enough to be seen Separate sexes Some are adapted to attach to gut wall Cause abdominal discomfort and pain Fecal oral tranmission Detected by microscopy and identification of adult worms
Describe hookworms
Cause chronic blood loss
Transmitted by larvae penetrating Skin
Detected by identification of ova or larvae in stool
Describe filariasis nematode in tissues
Filaria block lymph channels
Causes fevers, elephantiasis, swelling or deformity of limbs and genitalia
Tranmitted by mosquitos
Detection- parasite larvae (microfilaria) stained on blood film
Describe Ectoparasites
Colonize the body vs micro predators that bite only
Insects (6 legs) fleas, lice, bedbugs
Arachnida (8 legs) ticks and mites
Vectors of disease and cosmetic
