92. Arboviruses – Causative Agents of Significant Arboviral Infections
Introduces arboviruses as arthropod-borne viruses spread by mosquitoes, ticks and sandflies, noting that they span several unrelated virus families. Goes on to their shared features, a table of causative agents with vectors and diseases, and the pathogenesis of haemorrhagic, encephalitic and arthralgic syndromes. Closes with diagnostic methods, supportive treatment, vaccines and vector control.
Topic 92 of 113 in the MU Sofia syllabus for Microbiology (Medicine, Year 3). The free AceMed note covers it in 7 sections, about 238 words (3 min of reading), with 15 flashcards.
In this note
Arboviruses – Causative Agents of Significant Arboviral Infections
I. Definition and General Characteristics
II. Common Features of Arboviruses
III. Causative Agents and Diseases
IV. Pathogenesis and Syndromes
V. Diagnosis
VI. Treatment and Prevention
I. Definition and General Characteristics
Arboviruses = ARthropod-BOrne viruses – a group of viruses transmitted by blood-sucking arthropods such as mosquitoes, ticks, and sandflies.
They do not form a taxonomic group, but include viruses from several different families:
Flaviviridae
Togaviridae
Bunyaviridae
Reoviridae
Transmission cycle usually involves:
1. Arthropod vector (biological vector, not just mechanical)
2. Vertebrate host (often human, birds, monkeys, or rodents)
II. Common Features of Arboviruses
RNA viruses (except African swine fever virus – a DNA arbovirus).
Replicate in both arthropod vectors and vertebrate hosts.
Seasonal in temperate regions (depends on vector activity).
Major clinical syndromes:
Fever with or without rash
Hemorrhagic fever
Encephalitis
Arthritis-like symptoms (chikungunya)
IV. Pathogenesis and Syndromes
A. Hemorrhagic Fevers (Capillary leakage + bleeding)
Dengue hemorrhagic fever, Yellow fever, CCHF, Rift Valley fever
Mechanisms:
Cytokine storm
Endothelial damage
Platelet destruction and vascular leakage
B. Encephalitic Arboviruses
Japanese encephalitis, West Nile virus, Tick-borne encephalitis
Invade CNS → cause neuronal destruction, inflammation
Signs: altered mental status, seizures, coma
C. Arthralgic Illnesses
Chikungunya virus, Zika virus
Strong inflammatory response in joints and muscles
Often mimics rheumatoid arthritis in chronic cases
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