NBME 24 Formation of hypnozoites (NBME Answers)

NBME 24 Answers ↦

nbme24/Block 4/Question#41 (63.6 difficulty score)
A 30-year-old man who is a migrant farm ...
Formation of hypnozoites🔍
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+16
submitted by jejunumjedi(30),

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Teh obdlo asemr depitcs cfhfunSre siippt.gln onFud teh actex magei on het ewb whit :opieanxltna

~pevP/stljo3./exti/p2e_.us:o2trcth_/besii/ivsavcl/haap/ptampc/e4b..gmd/

doctorboomboom Hey thanks for finding the image! Do you know why the answer can’t be Chloroquine resistance? I was b/w that and formation of hypnozoites. +5

jejunumjedi I think it's just that Schuffner stippling and hypnozoites are both specific to vivax and ovale species. These species could be chloroquine resistant or sensitive, but if you have Schuffner stippling or hypnozoites, you can definitively say that it's either vivax or ovale. +3

sherry Species with hypnozoites is not called chloroquine resistant. Chloroquine-resistant species means trophozoite/schizont cant be killed by chloroquine. We dont have enough info to decide whether the spp in the q is resistant/sensitive. But we do know he moved from Honduras to USA 1 year ago. +3

soph UW: in africa most malaria species are resistant to chloroquine. he is from hondruas +4

randios Can anyone explain the 1-week history of fever? Ruled out vivax and ovale due to 48 hr cycles. Or did they just throw that in as an unspecific symptom. +1

dr_ligma unspecific symptom probably +

mcm94 how I know that is an infection by vivax/ovale ? if there's nothing that says about tertian fever? +

medguru2295 While it COULD be Chloroquine resistant, its not likely. This patient is likely infected with Vivax or ovale (not Falciparium) why? 1. Honduras (Falcip would be Africa) 2. Sx 1 year later (Liver form Vivax or OVale) 3. As many mentioned, Schuffer bodies Falciparium tends to be the species resistant to Chloroquine. Typically, Chloroquine is given for Vivax & Ovale (typically with something else- Atovaquone, Dapsone etc) to cover Liver Falciparium (no Liver form) is generally Chloroquine resistant (B) and therefore covered with Atovaquone/Proguanil. You do need 8-14 days of tx after coming for Falcip bc it can remain in the Liver for a few days (just not a dormant hypno form). To cover the "week of fever" question- its re-emergence of her sx. They probably just did not want to say cyclic to make it trickier. +4

flvent2120 Looks like it's been touched on, but you could answer this solely based on the fact that it's been one year since living in Honduras. While it MAY be chloroquine resistant, it IS dormant. Test taking skills would be to choose the answer you can't argue with +

+10
submitted by suckitnbme(176),

Even if you can't interpret the blood smear, this patient is presenting with malaria after being in the US for 1-year. It's highly unlikely that he got newly infected while in the US. What is occurring is a reactivation of dormant malaria (hypnozoites in the liver) that this dude got while in Honduras.

As such this is plasmodium vivax/ovale. What probably happened was that this patient was treated with chloroquine when he was initially infected. This would clear the infection in the bloodstream, but does not kill the hypnozoites in the liver. Treatment with primaquine is needed to clear the hypnozoites, which this patient likely did not receive, hence malaria while in the US.

+7
submitted by leny123(7),

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lnGeaer lrue - nuiehCqloor tivnieses if morf inCaaerbb ro nlaCrte riceamA wtes of amaanP laCn,a sith nteiapt gtrmemiida rofm uarHnosd os ouy nca tleimiena ilhceoqurno reacistnse sa an swrean eoihcc ni( dtdnaiio ot het vxlaaviove/ nfoi e)av.ob

charcot_bouchard Guys along with all intelligent discussion also keep in mind he immigrated 1 year back. So it must be hypnozoites which is causing this because Murica is Malaria free. +27

+1
submitted by yotsubato(1028),

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niKd fo tkryic n.esoquit eTh ytohensiopz are lrunheqoioc ns.ttaresi uBt eth pisesce aym tno be.

.P lpmcFuriaa is israttsne nda oslko keli a nnb,aaa tub oyu ondt nwko if teh mraiala in the CBR is maifprluca or .otn

tyrionwill whether resistant or sensitive, depends on the region, not on the species falci coming from Hatii could be sensitive +

+1
submitted by nwinkelmann(292),

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Found htsi terag mucdntoe itwh sdiels btoau teh tidneefrf athpgosn:e pr.pa2r_gcncns/dPitgat9ts/9h/2rp/G3mmstfp10a_hgSnec/1ioran.0b:r-ep0Si

+0
submitted by krewfoo99(93),

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I htink iueqhoclron ssaetnicre nwto be siecefpc ot ivavx nda tusleovh,a igknma it het irroccnte neswr.a oqlCuihonre eaessirtcn anc ylpap ot P. acialprFum dna .P relaaiaM

lOyn ivxva dna elova ecsau iohpntzoye suht gainkm atth the mero acerl swarne

+0
submitted by paperbackwriter(112),

Pg. 157 of 2019 FA picture B depicts Shuffner stippling under Malaria. "Seen with P vivax/ovale"

+0
submitted by nwinkelmann(292),

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Does ynoean nkow who ot lrue tou ?E v'eI nveer rndlaee uatob asgicornimmros csliyfaeclpi gniitcavat a leslc' CAMs, btu nehw I ldooke it pu, I ndouf shti ectrali (/mwtt/lnP./wwn/a.hn7t.op5//e.3rCch9icl3pcmsiigbM:0vs.) hTe eitcrla oends't fpcyasclilie ntneomi mmpiuoldas as sgnui it, ubt lraesev fo eth rucesreso orf het lcraite do.se