Question of the Day

Study for the USMLE Step 2, daily.

June 18, 2024

A 66-year-old male presents with chronic leg swelling. He is a recent immigrant from Fiji. He reports episodes of fever and headache. Physical exam reveals thick, scaly skin on both legs with swelling extending to the genitals. Swollen inguinal lymph nodes are palpable. What was the likely vector of transmission for his infection?

Correct Answer: 

D. Mosquito

Explanation:

This man exhibits the signs and symptoms of elephantiasis, a condition caused by the nematodes Wuchereria bancrofti and Brugia malayi. They are both spread by the bite of an infected mosquito (choice D). The lymphatics are infected, resulting in chronic leg and genital swelling. Wuchereria infection is endemic to the Pacific Islands, and much of Africa, whereas Brugia is found in the Malay Peninsula and much of Southeast Asia. Importantly, mosquitos are vectors for many other bacteria species, which you should be familiar with.

Fleas (choice A) may serve as vectors for the transmission of Yersinia pestis (bubonic plague) between rodents and humans. Murine typhus (endemic typhus) fever, and in some cases Hymenolepiasis (tapeworm) can also be transmitted by fleas.

Body Lice (choice B) serve as vectors for Rickettsia prowazekii, causing Epidemic typhus, Bartonella quintana (trench fever causing endocarditis commonly among the homeless), and Borrelia recurrentis (a recurrent fever found in east Africa).

Mites (choice C) bites may cause otitis or dermatitis and can act as vectors for Serratia marcescens or Staphylococcus intermedius/Staphylococcus chromogens.

The tick (choice E) can act as a vector for Borrelia Burgdorferi or Coxiella-like species. Most famously, tick bites carrying Borrelia are the cause of Lyme Disease.

Quick Concepts:

Elephantiasis (lymphatic filariasis)

– Common pathogens: Wuchereria bancrofti, Brugia malayi

– Common vector: Mosquito

– Common symptoms: Chronic lower extremity and genital swelling, painful lymphadenopathy

Summary:

Elephantiasis is a condition caused by the nematodes Wuchereria bancrofti and Brugia malayi. They are both spread by the bite of an infected mosquito.

Explanation:



Support Step 2 Daily to view full explanation.


$2.99/month


All Questions

Full Explanation

Questions by Email

Quick Concepts

Summary

& more


Sign Up or Login

Lorem ipsum dolor sit amet, consectetur adipisicing elit. Sint blanditiis perspiciatis nesciunt possimus minus molestiae culpa necessitatibus atque ut eveniet id magnam delectus reprehenderit! Ad atque aperiam rerum quas vitae!Lorem ipsum dolor sit amet, consectetur adipisicing elit.

Velit esse nihil iusto ea natus aliquam enim ducimus deleniti vitae quibusdam aperiam voluptatibus necessitatibus nulla id non consectetur commodi! Laborum nam.Lorem ipsum dolor sit amet, consectetur adipisicing elit.

Dolorem non quo laudantium doloremque necessitatibus deserunt sed vero officiis iste asperiores quasi quae nisi ab debitis dignissimos delectus cum repellat quidem.Lorem ipsum dolor sit amet, consectetur adipisicing elit. Modi a deserunt nostrum eos magni porro vel error dolore cupiditate iure sint fugiat rerum accusamus voluptates tenetur doloremque debitis ad reprehenderit?Lorem ipsum dolor sit amet, consectetur adipisicing elit.

Repellendus aut dolorum officia eos commodi sit cumque nulla impedit perspiciatis ipsum odit expedita harum praesentium ducimus id labore deserunt quo repellat.Lorem ipsum dolor sit amet, consectetur adipisicing elit. Odit in voluptas excepturi perspiciatis iste vel laborum sunt nostrum quaerat laboriosam enim amet molestiae fugiat quos illum recusandae cum asperiores.

Repellendus aut dolorum officia eos commodi sit cumque nulla impedit perspiciatis ipsum odit expedita harum praesentium ducimus id labore deserunt quo repellat.Lorem ipsum dolor sit amet, consectetur adipisicing elit.



Step 2 Questions

Sign up for Step 2 Emails