39.1 CASE STUDY

Patient (male – 28 years) travelling repeatedly to the tropic countries. In January he travelled to Mali, and did not take antimalarial prophylaxis. He was repeatedly bitten by mosquitoes, headache appeared on 7 days after the biggest bite, day 2 fever with chills and subsequent sweating. What was the differential diagnosis of infectious agents in this patient? What was the most likely etiologic agent?


What tests would have been done to confirm the diagnosis?

The clinical presentation of fever with chills and subsequent sweating, especially following travel to a tropical country where the patient was bitten by mosquitoes, is highly suggestive of malaria. Given the destination of Mali and the timing of the onset of symptoms, malaria would be at the top of the differential diagnosis.

Differential Diagnosis:

Malaria + Dengue Fever + Yellow Fever + Chikungunya + Zika virus + West Nile virus + Typhoid

  • Malaria: The most likely culprit, especially considering the destination (Mali) and the timing of symptoms after mosquito bites. There are four primary species of Plasmodium responsible for malaria in humans: P. falciparum, P. vivax, P. ovale, and P. malariae. Given the location and the rapid onset of severe symptoms, P. falciparum is the most likely causative species.

  • Dengue Fever: Another mosquito-borne illness that can present with fever, headache, and muscle/joint pains. It's prevalent in tropical and subtropical regions.

  • Yellow Fever: A viral illness transmitted by mosquitoes, causing fever, headache, jaundice, muscle pain, and nausea/vomiting.

  • Chikungunya: A viral illness characterized by fever and severe joint pain, spread by mosquitoes.

  • Zika Virus: Transmitted primarily through the bite of an infected Aedes species mosquito. It usually causes a mild illness but is known more for its potential risks in pregnancy.

  • West Nile Virus: Most people infected with West Nile virus do not feel sick, but one in five people who are infected develop a fever and other symptoms.

  • Typhoid: Bacterial infection caused by Salmonella Typhi, associated with fever, headache, and abdominal symptoms.

Given the symptoms and history, malaria, particularly P. falciparum, is the most likely etiologic agent.

Diagnostic Tests:

Thick and Thin blood smears + Rapid diagnostic tests + Polymerase chain reaction + Complete blood count + Liver and kidney function tests

  • Thick and Thin Blood Smears: The gold standard for malaria diagnosis. A drop of the patient's blood is smeared on a slide and stained to identify and differentiate between Plasmodium species.

  • Rapid Diagnostic Tests (RDTs): These detect antigens produced by malaria parasites. They can provide results in 15-20 minutes.

  • Polymerase Chain Reaction (PCR):More sensitive than microscopy and can be used to confirm the species of Plasmodium.

  • Complete Blood Count (CBC): Might show anemia, thrombocytopenia, or elevated white blood cells.

  • Liver and Kidney Function Tests: To assess the impact on these organs.

If malaria is suspected, it's crucial to initiate diagnostic tests promptly as P. falciparum malaria can progress rapidly and be fatal if not treated in time.

Mind Map: Differential Diagnosis of Infectious Agents in a Patient Travelling to Tropic Countries

Central Idea: Patient (male – 28 years) travelling repeatedly to tropic countries

Main Branches:

  • Differential Diagnosis

  • Most Likely Etiologic Agent

  • Diagnostic Tests

Differential Diagnosis:

  • Malaria

  • Dengue Fever

  • Yellow Fever

  • Chikungunya

  • Zika Virus

  • West Nile Virus

  • Typhoid

Malaria:

  • Most likely etiologic agent

  • Four primary species: P. falciparum, P. vivax, P. ovale, P. malariae

  • P. falciparum is most likely in this case

Dengue Fever:

  • Mosquito-borne illness

  • Presents with fever, headache, muscle/joint pains

Yellow Fever:

  • Viral illness transmitted by mosquitoes

  • Symptoms: fever, headache, jaundice, muscle pain, nausea/vomiting

Chikungunya:

  • Viral illness characterized by fever and severe joint pain

  • Spread by mosquitoes

Zika Virus:

  • Transmitted through mosquito bites

  • Mild illness, but risks in pregnancy

West Nile Virus:

  • Many infected individuals don't feel sick

  • Symptoms: fever, other flu-like symptoms

Typhoid:

  • Bacterial infection caused by Salmonella Typhi

  • Symptoms: fever, headache, abdominal symptoms

Diagnostic Tests:

  • Thick and Thin Blood Smears

  • Rapid Diagnostic Tests (RDTs)

  • Polymerase Chain Reaction (PCR)

  • Complete Blood Count (CBC)

  • Liver and Kidney Function Tests

Thick and Thin Blood Smears:

  • Gold standard for malaria diagnosis

  • Identifies and differentiates Plasmodium species

Rapid Diagnostic Tests (RDTs):

  • Detects malaria parasite antigens

  • Provides quick results (15-20 minutes)

Polymerase Chain Reaction (PCR):

  • More sensitive than microscopy

  • Confirms Plasmodium species

Complete Blood Count (CBC):

  • May show anemia, thrombocytopenia, elevated white blood cells

Liver and Kidney Function Tests:

  • Assesses impact on these organs

Note: Prompt initiation of diagnostic tests is crucial for suspected malaria cases, especially P. falciparum, to prevent complications and fatalities.