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Questions and Answers
Which laboratory test result is commonly associated with Brucellosis?
Which laboratory test result is commonly associated with Brucellosis?
What is a key opportunistic infection associated with HIV pathogenesis?
What is a key opportunistic infection associated with HIV pathogenesis?
When investigating a fever of unknown origin, which investigation is most relevant?
When investigating a fever of unknown origin, which investigation is most relevant?
Which of the following is a common complication of AIDS?
Which of the following is a common complication of AIDS?
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What is a typical symptom of a Brucella infection?
What is a typical symptom of a Brucella infection?
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What is the best diagnostic test for Brucellosis?
What is the best diagnostic test for Brucellosis?
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Which of the following are common complications associated with AIDS?
Which of the following are common complications associated with AIDS?
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Which symptom is NOT associated with Brucellosis?
Which symptom is NOT associated with Brucellosis?
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What is the initial treatment for Brucellosis?
What is the initial treatment for Brucellosis?
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Which mode of infection is primarily associated with HIV?
Which mode of infection is primarily associated with HIV?
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What best characterizes Fever of Unknown Origin (FUO)?
What best characterizes Fever of Unknown Origin (FUO)?
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Which opportunistic infection is most closely related to AIDS?
Which opportunistic infection is most closely related to AIDS?
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What is a key feature of the clinical presentation of AIDS?
What is a key feature of the clinical presentation of AIDS?
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Which of the following is a common mode of transmission for Brucella infections?
Which of the following is a common mode of transmission for Brucella infections?
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What is a key symptom associated with acute Brucellosis?
What is a key symptom associated with acute Brucellosis?
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Which laboratory investigation is primarily used for diagnosing Fever of Unknown Origin?
Which laboratory investigation is primarily used for diagnosing Fever of Unknown Origin?
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Which complication is most commonly associated with AIDS?
Which complication is most commonly associated with AIDS?
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In HIV pathogenesis, which process leads to a decrease in CD4 T-cell counts?
In HIV pathogenesis, which process leads to a decrease in CD4 T-cell counts?
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What is one of the main bacterial causes of fever associated with travel to endemic regions?
What is one of the main bacterial causes of fever associated with travel to endemic regions?
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Which of the following is NOT a symptom of acute HIV infection?
Which of the following is NOT a symptom of acute HIV infection?
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In cases of brucellosis, which of the following is an important aspect of treatment?
In cases of brucellosis, which of the following is an important aspect of treatment?
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Study Notes
Infectious Diseases Overview
- Infectious diseases are a broad category encompassing various illnesses caused by pathogenic agents.
- Learning objectives for this topic include understanding the pathophysiology, etiology, epidemiology, manifestations, complications, and management of key infectious diseases.
- Knowledge of clinical manifestations and investigations is vital for reasonable diagnosis and implementing an effective management plan.
Aetiological Classification
-
Bacterial:
- Gram-positive: streptococci, staphylococci
- Gram-negative: Klebsiella, Pseudomonas, Haemophilus influenza
- Anaerobic bacteria: Bacteroides
- Mycobacterial: Tuberculosis (TB), Leprosy
- Spirochetal: Syphilis, Leptospirosis
- Rickettsial: Typhus
- Chlamydia
- Viral: Dengue, influenza, Herpes Simplex Virus (HSV), Varicella-Zoster Virus (VZV), Cytomegalovirus (CMV), Epstein-Barr virus (EBV), Measles, Mumps, Rubella
- Protozoal: Malaria, Amebiasis, Bilharzia, Giardiasis
- Fungal: Candida albicans, Aspergillus niger
Fever and its Types
- Normal body core temperature ranges from 36.5°C to 37.2°C.
- Fever (pyrexia): an increase in body temperature above the normal upper limit.
- Types of fever:
- Sustained fever: daily fluctuations of fever less than 1°C
- Remittent fever: daily fluctuations of fever more than 1°C
- Hectic fever: body temperature falls to normal once or more during the day.
- Relapsing fever: days of fever interrupted by days of normal temperature
- Hyperpyrexia: body temperature > 40°C
Typhoid Fever
- Aetiology: Caused by Salmonella typhi and paratyphi A & B; transmitted through feco-oral route.
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Clinical manifestations:
- Week 1: Step-ladder fever, headache, relative bradycardia, constipation, rash (rose spots).
- Week 2: continuous fever, tachycardia, diarrhea, splenomegaly.
- Week 3: convalescence begins
- Complications: Intestinal bleeding, peritonitis, meningitis, encephalitis, convulsions, pyelonephritis.
- Investigations: CBC (leucopenia with relative lymphocytosis), Widal test (+ve from 2nd week), blood, stool & urine cultures (+ve in week 1, 2, & 3, respectively – best diagnostic).
- Treatment: Ciprofloxacin, co-trimoxazole (septrin), ceftriaxone.
Brucellosis
- Etiology: Caused by Brucella (melitensis, abortus, or suis)
- Mode of infection: Contaminated milk or remnants of aborted animals
- Clinical picture: Bone & muscle pain, vomiting, constipation, relapsing fever (days of fever alternating with fever-free periods).
- Complications: Relapse, infective endocarditis, orchitis, paraplegia from transverse myelitis, abortion
- Investigations: CBC (lymphocytosis during fever spike), Blood Culture (+ve during fever), Serological tests (Brucella agglutination test - best diagnostic test)
- Treatment: Doxycycline or rifampicin for 6 weeks
Acquired Immunodeficiency Syndrome (AIDS)
- Aetiology: Infection with Human Immunodeficiency Virus (HIV).
- Modes of infection: Parenteral, sexual, vertical
- Clinical picture: Asymptomatic (lasting up to 10 years), Acute HIV syndrome (fever, rigors, arthralgia, rash for 2 weeks), symptomatic syndromes, and generalized lymphadenopathy.
- Opportunistic Infections: Cytomegalovirus (CMV), Herpes Simplex Virus (HSV), Tuberculosis (TB), Pneumocystis carinii Pneumonia.
- Secondary Neoplasms: Kaposi sarcoma, Non-Hodgkin's lymphoma.
- Investigations: HIV antibodies (screening), HIV-RNA by PCR (diagnostic).
- Treatment: Antiretroviral therapies (HAART), Zidovudine 600 mg/day orally.
Fever of Unknown Origin (FUO)
- Definition: Persistent elevation of body temperature over 38.5°C for 3 weeks, without a specific diagnosis after at least one week of inpatient investigations.
- Causes: Infections (bacterial, viral, protozoal), Malignancy (hematologic or non-hematologic), Collagen disease, other conditions.
Pulmonary Tuberculosis (TB)
- Definition: Chronic infection of the lung caused by Mycobacterium tuberculosis, aerobic, non-motile, acid-fast bacillus.
- Aetiology: M. Tuberculosis. Predisposing factors include children under 5, contacts with open TB patients, and immunocompromised individuals (e.g., AIDS, diabetes, leukemia, steroid use).
- Mode of transmission: Droplet infection.
- Symptoms: Toxic manifestations (night fever, sweating, weight loss), cough with sputum (mucoid, mucopurulent, sometimes blood-tinged), and chest signs.
- Clinical features: Consolidation to cavitation and fibrosis, possible CNS involvement.
- Investigations: Chest X-ray, ESR, C-reactive protein (CRP), sputum microscopy and culture, PCR, tuberculin skin test, and serological tests (Quantiferon Gold, anti-deaminase antibody (ADA)).
- Treatment: First-line drugs (isoniazid (INH), rifampicin, pyrazinamide, ethambutol, streptomycin) combined for a long period, standard regimen for 6 months.
Dengue Fever
- Definition: A viral disease caused by the dengue virus.
- Aetiology: RNA virus (Flavivirus, arbovirus).
- Vector: Mosquito Aedes aegypti
- Pathogenesis: Virus inoculated by mosquito bite, replication in reticuloendothelial system, leads to immune response, causing lymphocytic vasculitis and capillary leakage, resulting in possible complications.
- Clinical features: Incubation period (5-9 days), fever, rapid defervescence, headache, mouth/nose bleeding, muscle pain, vomiting, rash, photophobia, eye pain, and various others, depending on the stage and type of dengue infection.
- Complications: Dengue Shock Syndrome (DSS) and Dengue Hemorrhagic Fever (DHF).
- Investigations: Elevated hematocrit, leucopaenia, low platelets, elevated liver enzymes, and serological tests (dengue antibody IgM and IgG ELISA), and PCR.
- Management: Supportive, including intravenous crystalloids, paracetamol, platelet infusion and FFP.
Prevention
- Hand hygiene: 5 moments approach for hand hygiene, alcohol-based hand sanitizers, and use of appropriate personal protective equipment (PPE).
- Respiratory precautions: Report symptoms of acute respiratory illness, covering mouth, proper hand hygiene, and tissue disposal, and provision of protective measures in specific cases.
Other information
- The presentation includes references.
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Description
Explore the vast field of infectious diseases, focusing on their pathophysiology, etiology, and epidemiology. This quiz will test your knowledge on various classifications of infectious agents, including bacteria, viruses, and protozoa, along with their clinical manifestations and management strategies.
