QOD 1 3 10

Household contacts in which of the following age groups are most susceptible to H1N1 infection, according to the results of this week's NEJM published study?
		A.	18 years of age or younger.
		B.	19 to 50 years of age.
		C.	51 to 69 years of age. D. 70 years of age or older Results An acute respiratory illness developed in 78 of 600 household contacts (13%). In 156 households (72% of the 216 households), an acute respiratory illness developed in none of the household contacts; in 46 households (21%), illness developed in one contact; and in 14 households (6%), illness developed in more than one contact. The proportion of household contacts in whom acute respiratory illness developed decreased with the size of the household, from 28% in two-member households to 9% in six-member households. Household contacts 18 years of age or younger were twice as susceptible as those 19 to 50 years of age (relative susceptibility, 1.96; Bayesian 95% credible interval, 1.05 to 3.78; P=0.005), and household contacts older than 50 years of age were less susceptible than those who were 19 to 50 years of age (relative susceptibility, 0.17; 95% credible interval, 0.02 to 0.92; P=0.03). Infectivity did not vary with age. The mean time between the onset of symptoms in a case patient and the onset of symptoms in the household contacts infected by that patient was 2.6 days (95% credible interval, 2.2 to 3.5). Conclusions The transmissibility of the 2009 H1N1 influenza virus in households is lower than that seen in past pandemics. Most transmissions occur soon before or after the onset of symptoms in a case patient. Answer: A

QOD 1 4 10

Which of the following statements is true regarding thrombolysis in cases of frostbite?
		A.	Doppler signals should be detectable in the extremity before thrombolysis.
		B.	Infusion of vasodilators should be avoided.
		C.	Intraarterial infusion of the thrombolytic agent is preferred.
		D.	Priority should be given to the feet rather than the hands. After rewarming, if the patient's feet or hands remain without evidence of perfusion, the presence of vascular thrombosis should be suspected. In this situation, emergency lytic therapy would seem to address the primary pathophysiology, if ischemia time has been brief. Intravenous or intraarterial thrombolytic therapy has been reported in two retrospective studies to reduce the rate of major amputation. Because it is primarily the smaller arteries that are occluded in frostbite, thrombolytic agents may be more effective when selectively infused intraarterially, with the catheter tip positioned near the target areas of malperfusion. Catheter-directed administration of tissue plasminogen activator (t-PA) may be more effective, since a higher concentration of the agent locally permeates and binds to thrombus at the target. The use of an ultrasound-accelerated thrombolysis catheter to deliver the thrombolytic agent has been performed; ultrasonography has been shown to reversibly loosen fibrin strands and reduce their diameter, exposing more individual strands, increasing thrombus permeability, and exposing more plasminogen-receptor sites for binding. More rapid and complete thrombolysis has been reported with the use of this technique than with standard catheter-directed thrombolysis. The treatment end points for thrombolytic therapy include angiographic or clinical demonstration that perfusion has been reestablished, failure to show any improvement in perfusion on angiograms obtained after 24 hours and after 48 hours of therapy, and the development of bleeding complications such as hematoma, stroke, or hemorrhage involving solid organs or the gastrointestinal tract. Answer: C