Vector-borne Flashcards
Which rodents are associated with plague?
Mastomys natalensis
Rattus rattus (black rat)
What treatment can be given to people associated with patients infected with plague?
Bactrim
Doxycycline
What are the forms of plague?
Bubonic
Pneumonic
Carbuncular
Can causes sepsis (enterobacter - gram negative sepsis)
What type of bacteria is yersinia pestis?
Obligate intracellular
What are the 3 major filarial infections?
Lymphatic filariasis
Onchocerciasis
Loiasis
Which organism causes lymphatic filariasis?
W. bancrofti
Which organism causes onchocerciasis?
O. volvulus
Which organism causes loiasis?
Loa loa
What is the life cycle of filaria?
Vector feeds on human host and transmits larval stage -> adult worms develop in host tissue and mate -> microfilariae produced -> vectors ingest the microfilariae -> larval stage develops in the vector
Cannot have more adult worms without repeated bites!
Where do adult worms live in lymphatic filariasis?
Efferent lymphatic vessels
Which mosquitoes transmit w. bancrofti?
Anopheles
Culex
Describe the behavior of w. bancrofti worms
Nocturnal (except the South Pacific worms which are diurnal)
What are 2 other lymphatic filariae?
Brugia malayi
Brugia timori
When does lymphatic filariasis become irreversible?
Elephantiasis (hard, fibrous tissue)
How can lymphatic filariasis present?
Hydrocele
Lower limb oedema
Chyluria
How do you distinguish w. bancrofti from loa loa?
W. bancrofti - no nuclei at tail end
What is the vector of loa loa?
Tabanid flies eg chrysops
What is loa loa also called?
African eye worm
How does epidemiology between lymphatic filariasis differ?
W. bancrofti - worldwide
Loa loa - central and western africa
Which condition presents with calabar swelling?
Loa loa
What is the vector of onchocerciasis?
Blackfly
What are the 2 target sites of onchocerciasis?
Skin (dermatitis and leopard skin depigmentation)
Eye (river blindness)
Which microfilariae causes intense eosinophilic inflammatory response on death?
O. volvulus
Where do o. volvulus reside?
Onchocercal nodules (subcutaneous tissue, usually over bony prominences)
Why is ivermectin treatment given annually for onchocerciasis?
Does not kill the adult worm
Which microfilariae have wolbachia endosymbiote?
W. bancrofti
O. volvulus
Which stage does ivermectin affect?
Microfilariae
Which microfilariae have ivermectin indicated for treatment?
All
Which stage does albendazole affect?
Adult worm
Which stage does doxycycline affect?
Female worm
Which stage does diethylcarbamazine affect?
Micro + adult
Which microfilariae have albendazole indicated for treatment?
Loaisis
Which microfilariae have doxycyline indicated for treatment?
Bancrofti + oncho
Which microfilariae have diethylcarbamazine indicated for treatment?
Bancrofti + loa
Which drugs are contraindicated in oncho?
Albendazole
Diethylcarbamazine
What are the 3 groups of rickettsial infections?
Spotted fever group
Typhus group
Other - no longer rickettsias
Which conditions fall under spotted fever group?
African tick bite fever
Boutonneuse/Mediterranean spotted fever
Tick typhus (Queensland, Siberian, Kenyan, Japanese)
Rocky mountain spotted fever
Rickettsialpox
Flea associated (R. felis)
Which conditions fall under typhus group?
Louse born (epidemic) typhus
Flea borne (endemic, murine) typhus
Which conditions are no longer rickttsias?
Q fever (c. burnetii)
Scrub typhus (orienta tsutsugamushi) - mite borne
Which tick causes Boutonneuse fever-like infection and what is the usual vector, transmission and reservoir?
R. conorii
Vector - dogs
Reservoir - rodents, dogs, ticks
Transmission - peri-urban and peri-domestic
What are the clinical features of Boutonneuse fever-like infection?
5-7d incubation
Prodrome = malaise, fever, headache, nightmares, myalgia
Primary lesion = eschar
Rash after 3 days (coarse, maculopapular, palms and soles)
Which tick causes african tick bite fever and what is the usual vector, transmission and reservoir?
R. africae
Vector = cattle ticks (ambiyamma genus)
Reservoirs = cattle, game, ticks
Transmission = rural
What are the clinical features of african tick bite fever?
Milder than Boutonneuse
Multiple eschars
Tender regional lymphadenopathy
Rashless/scattered rash
What are complicators of rickettsial infection?
Encephalitis
Confusion
Coma
Pneumonia
DIC
Bleeding gangrene
Renal failure
How is rickettsial infection diagnosed?
Direct
- immunofluorescence
- PCR
Serology
- specific immunofluorescence
- Weil-Felix (obsolete)
Discuss treatment of rickettsial infection
Tetracyclines
Clinical response takes 2 days
In young children/pregnancy consider 2 doses doxy then macrolide
Macrolide alone has slower response
