Infectious diseases for AMC MCQ

A 29 year old man presents with five days of high fever, shaking chills, drenching sweats, headache and muscle aches, two weeks after returning from a month in rural sub-Saharan Africa. He took no antimalarial prophylaxis. He is febrile with a palpable spleen but is alert and haemodynamically stable, and his thick and thin films show Plasmodium falciparum at a low parasite count. What is the most likely diagnosis?

1. Sepsis (including neutropenic sepsis) Fever with systemic upset from another source. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes it a consideration.
2. Amoebic liver abscess Fever and right upper quadrant pain after travel. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes it a consideration.
3. Malaria correct Correct. Fever with rigors and sweats in a returned traveller with falciparum on the film is malaria.
4. Influenza A febrile viral illness. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes travel history matter.
5. Viral hepatitis Fever with jaundice and deranged liver enzymes. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes it worth considering.

The point: Malaria must be considered in any febrile traveller returning from an endemic area, and the single most important rule is that fever after travel is malaria until proven otherwise. It is caused by Plasmodium species transmitted by mosquitoes; Plasmodium falciparum is the dangerous one, capable of causing severe, rapidly fatal disease, and it usually presents within a month of return, while Plasmodium vivax and ovale can relapse months later from dormant liver forms. The presentation is non-specific: fever, often but not always cyclical, with chills, rigors, sweats, headache, myalgia, and sometimes diarrhoea or jaundice, and examination may show only fever and splenomegaly. The diagnosis rests on thick and thin blood films for the parasite and species with a parasite count, repeated up to three times if the first is negative, supported by rapid antigen tests. Severe falciparum malaria is defined by impaired consciousness, shock, acidosis, hypoglycaemia, severe anaemia, renal failure, pulmonary oedema or a high parasite count, and it is treated as an emergency with parenteral artesunate. Uncomplicated malaria is treated with an appropriate oral regimen by species and resistance, and vivax and ovale need additional treatment to clear the liver stage after checking for G6PD deficiency. Prevention is by bite avoidance and chemoprophylaxis.

Source: Therapeutic Guidelines (Australia) — Antibiotic: malaria Therapeutic Guidelines (Australia) · tier 3, national formulary

A 29 year old man presents with five days of high fever, shaking chills, drenching sweats, headache and muscle aches, two weeks after returning from a month in rural sub-Saharan Africa. He took no antimalarial prophylaxis. He is febrile with a palpable spleen but is alert and haemodynamically stable, and his thick and thin films show Plasmodium falciparum at a low parasite count. What is the most appropriate initial investigation?

1. Thick and thin blood films with parasite count correct Correct. The films confirm the species and the parasite count that grades severity.
2. Blood cultures and a broad febrile screen For alternatives. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes it worthwhile.
3. Full blood count, renal and liver function and glucose For complications. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes it important.
4. Rapid malaria antigen test Supports the diagnosis. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes it useful.
5. Assessment for severe or falciparum disease Consciousness, acidosis and parasite count. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes it discriminating.

The point: Malaria must be considered in any febrile traveller returning from an endemic area, and the single most important rule is that fever after travel is malaria until proven otherwise. It is caused by Plasmodium species transmitted by mosquitoes; Plasmodium falciparum is the dangerous one, capable of causing severe, rapidly fatal disease, and it usually presents within a month of return, while Plasmodium vivax and ovale can relapse months later from dormant liver forms. The presentation is non-specific: fever, often but not always cyclical, with chills, rigors, sweats, headache, myalgia, and sometimes diarrhoea or jaundice, and examination may show only fever and splenomegaly. The diagnosis rests on thick and thin blood films for the parasite and species with a parasite count, repeated up to three times if the first is negative, supported by rapid antigen tests. Severe falciparum malaria is defined by impaired consciousness, shock, acidosis, hypoglycaemia, severe anaemia, renal failure, pulmonary oedema or a high parasite count, and it is treated as an emergency with parenteral artesunate. Uncomplicated malaria is treated with an appropriate oral regimen by species and resistance, and vivax and ovale need additional treatment to clear the liver stage after checking for G6PD deficiency. Prevention is by bite avoidance and chemoprophylaxis.

Source: Therapeutic Guidelines (Australia) — Antibiotic: malaria Therapeutic Guidelines (Australia) · tier 3, national formulary

A 29 year old man presents with five days of high fever, shaking chills, drenching sweats, headache and muscle aches, two weeks after returning from a month in rural sub-Saharan Africa. He took no antimalarial prophylaxis. He is febrile with a palpable spleen but is alert and haemodynamically stable, and his thick and thin films show Plasmodium falciparum at a low parasite count. What is the most appropriate next step in management?

1. Appropriate oral regimen for uncomplicated malaria correct Correct. Alert, stable, low-count falciparum is uncomplicated and treated with an appropriate oral regimen.
2. Exclude co-infection and other travel illness Where relevant. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes it thorough.
3. Liver-stage treatment for vivax and ovale after G6PD testing To prevent relapse. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes it directed.
4. Admit and monitor falciparum malaria For deterioration. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes it the escalation.
5. Bite avoidance and chemoprophylaxis advice for prevention For future travel. Fever with rigors in a returned traveller with low-count falciparum and no severe features makes it preventive.

The point: Malaria must be considered in any febrile traveller returning from an endemic area, and the single most important rule is that fever after travel is malaria until proven otherwise. It is caused by Plasmodium species transmitted by mosquitoes; Plasmodium falciparum is the dangerous one, capable of causing severe, rapidly fatal disease, and it usually presents within a month of return, while Plasmodium vivax and ovale can relapse months later from dormant liver forms. The presentation is non-specific: fever, often but not always cyclical, with chills, rigors, sweats, headache, myalgia, and sometimes diarrhoea or jaundice, and examination may show only fever and splenomegaly. The diagnosis rests on thick and thin blood films for the parasite and species with a parasite count, repeated up to three times if the first is negative, supported by rapid antigen tests. Severe falciparum malaria is defined by impaired consciousness, shock, acidosis, hypoglycaemia, severe anaemia, renal failure, pulmonary oedema or a high parasite count, and it is treated as an emergency with parenteral artesunate. Uncomplicated malaria is treated with an appropriate oral regimen by species and resistance, and vivax and ovale need additional treatment to clear the liver stage after checking for G6PD deficiency. Prevention is by bite avoidance and chemoprophylaxis.

Source: Therapeutic Guidelines (Australia) — Antibiotic: malaria Therapeutic Guidelines (Australia) · tier 3, national formulary