Infectious diseases Flashcards
What’s the causative organism of Lyme disease?
Borrelia burgdorferi,
spread by ticks
What are the early features of Lyme disease (within 30 days)?
- Erythema migrans:
a) bulls-eye rash, at site of bite,
b) typically over 1-4 weeks after the initial bite.
c) Painless,
d) >5cm in diameter, slowly increasing. - Systemic features:
a) headache,
b) lethargy
c) fever
d) arthralgia
What are the late features of Lyme disease (after 30 days)?
- Cardiovascular:
a) heart block
b) peri/myocarditis - Neurological
a) facial nerve palsy
b) radicular pain
c) meningitis
how do we diagnose Lyme disease?
- clinically if erythema migrans present - this is indication for starting abx
- ELISA antibodies to Borrelia burgdorferi are first line
a) if -ve but still you suspect lyme in those within first 4 weeks of symptoms - repeat ELISA in 4-6 weeks, if still negative in those with high suspicious, who had symptoms for 12 weeks or more, immunoblot test should be done.
b) if ELISA positive or equivocal then immunoblot test for lyme disease should be done.
What’s the management of asymptomatic tick bites?
- if ttick still present, remove using fine-tipped tweezers, and wash the area post.
- no routine abx needed.
What’s the management of suspected/confirmed Lyme disease?
- doxycycline if early disease, Amox is alternative option if doxy contraindicated e.g. pregnancy.
- ceftraixone if disseminated disease.
NB
- Jarisch-Herheimer reaction is sometimes seen after initiating theray: fever, rash, tachycardia after 1st dose of Abx (more common in syphilis).
What are some of the options available for malaria prophylaxis?
Drug (common side effects),
- Atovaquone + Proguanil, this combo is also called Malarone (GI upset) - begin 1-2days before travel, end 1 week after travel.
- Chloroquine (headache, CI in epilepsy), taken weekly. Start 1 week before and stop 4 weeks after travel.
- Doxycycline (photosensitivity, oesophagitis) - start 1-2 days before and for upto 4 weeks after travel.
- Mefloquine also called Lariam (dizziness, neuropschiatric disturbance, CI in eiplepsy), taken weekly. Start 2-3 weeks before and stop 4 weeks after travel.
What Malaria prophylaxis options are available for pregnant women?
- Pregnant should avoid travelling to malaria endemic regions if avoidable.
- Chloroquine can be taken.
- Proguanil - with folate (5mg) supplement.
- Malarone - BNF advises to avoid these unless essential and to take with folate supplement.
- doxycycline - contraindicated.
Which antimalarial prophylaxis can be taken by children?
- Diethytoluamide (DEET) 20-50% - repel upto 100% of mosquitoes, if used correctly - can be used in children over 2 months of age.
- Doxycycline only licensed in teh uk for children >12 yrs.
What’s the commonest cause of diarrhoea in HIV ptients?
Cryptosporidium + other protozoa (most common).
other less common causes are:
- CMV
- Myobacterium avium intracellulare
- Giardia
What are features of primary syphilils?
- Chancre - painless ulcer at site of sexual contact
- local non-tender lymphadenopathy
- often not seen in women (lesion may be on cervix).
What are features of secondary syphilis and when do they occur?
- occur 6-10 weeks after primary
- systemic symptoms: fever, lymphadenopathy
- rash on trunk, palms and soles.
- buccal ‘snail track’ ulcer (30%)
- condylomata lata (painless, warty lesions on genitalia).
What are features of tertiary syphilis?
- gummas (granulomatous lesions of skin and bone).
- ascending aortic aneurysm
- general paralysis of the insane
- tabes dorsalis
- argyll-robertson pupil
