Zika, Dengue, Chikungunya

Rheumatic symptoms should now prompt physicians to include mosquito-borne illnesses in differential diagnosis
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Zika, Chikungunya and Dengue. These viruses share the same vector: the Aedes aegypti mosquito. Arthralgia, or outright arthritis, can be the predominant presenting symptom.

How to Spot Chikungunya and Its Mimics

Diagnosis of chikungunya is quite straight-forward as it is based on serologic identification of polymerase chain reaction (PCR), but clinicians must be aware of the virus to order diagnostic tests.

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Immunology Explore this journal > Explore this journal > Previous article in issue: Interleukin-17A: a unique pathway in immune-mediated diseases: psoriasis, psoriatic arthritis and rheumatoid arthritis Previous article in issue: Interleukin-17A: a unique pathway in immune-mediated diseases: psorias...
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The potentially life-threatening aspects of Dengue infection, namely Dengue Haemorrhagic Fever and Dengue Shock Syndrome, are immune-mediated.

90% of these occur in the context of a secondary Dengue infection with a different serotype. A prominent immune mechanism accounting for this phenomenon is Antibody Dependent Enhancement (ADE).

The antibodies produced are specific against the previously encountered/vaccinated serotype, but they can cross-react with the current (and different) serotype without neutralising it. Instead, these antibodies facilitate viral uptake into monocytes and macrophages through Fc-receptor binding, thereby acting like trojan horses. Once inside the target cells, viral replication runs amok, triggering a massive Th1 and Th17 immune response, eventually culminating in a cytokine storm.

If such an immunological mechanism is accurate, there are 2 important implications:
1) immunomodulation with targeted therapies like anti-TNF and anti-IL17A may emerge as feasible adjuncts in the treatment of severe Dengue complications, beyond the current merely supportive paradigm;
2) vaccinations which do not cover all 4 serotypes may do more harm than good by priming an entire previously unexposed populace for ADE.

Immunology and Cell Biology - Of cascades and perfect storms: the immunopathogenesis of dengue haemorrhagic fever-dengue shock syndrome (DHF/DSS)

Immunology and Cell Biology focuses on the general functioning of the immune system in its broadest sense, with a particular emphasis on its cell biology. Areas that are covered include but are not limited to: Cellular immunology, Innate and adaptive immunity, Immune responses to pathogens,Tumour im...
nature.com

Infection with Zika virus has occurred in areas previously exposed to dengue virus, a closely related flavivirus. Screaton and colleagues find that monoclonal antibodies to dengue virus cross-react with Zika virus and enhance infection.
nature.com

"Plasma immune to DENV showed substantial cross-reaction to ZIKV and was able to drive antibody-dependent enhancement (ADE) of ZIKV infection."

This is worrisome if true. Is ADE the pathogenic mechanism for the autoimmune phenomena like Guillain-Barre Syndrome, and perhaps even microcephaly? The Dengue-endemic populace would therefore naturally be at far higher risk to develop such complications from Zika infection.

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