In-depth molecular analysis of a small cohort of #human and #Aedes #mosquito (adults and larvae) samples from #Kolkata revealed absence of #Zika but high prevalence of #dengue virus (J Med Microbiol., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

J Med Microbiol. 2018 Jun 13. doi: 10.1099/jmm.0.000769. [Epub ahead of print]

In-depth molecular analysis of a small cohort of human and Aedes mosquito (adults and larvae) samples from Kolkata revealed absence of Zika but high prevalence of dengue virus.

Sukla S1, Ghosh A1, Saha R2, De A3, Adhya S1, Biswas S1.

Author information: 1 ​CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata 700032, West Bengal, India. 2 ​Department of Microbiology, Calcutta National Medical College and Hospital, Kolkata 700014, West Bengal, India. 3 ​Department of Dermatology, Calcutta National Medical College and Hospital, Kolkata 700014, West Bengal, India.

 

Abstract

PURPOSE:

Zika virus infections have recently been reported in many dengue-endemic areas globally. Both dengue (DENV) and Zika (ZIKV) virus are transmitted by Aedes mosquitoes, raising the possibility of mixed infections in both vector and host. We evaluated DENV and ZIKV prevalence in human and vector samples in Kolkata, a DENV-endemic city.

METHODOLOGY:

Blood samples were collected from 70 patients presenting dengue-like fever symptoms at a hospital in Kolkata during 2015-16. Serum was obtained and tested for DENV infection by DENV NS1-based ELISA. Adult (n=8) and larval stages (n=12) of Aedes were also collected. A RT-PCR-based screening of both viruses supplemented by amplicon sequencing was performed.

RESULTS:

Of the 70 samples, 20 DENV NS1-positive serum samples were used for detailed molecular study for DENV infection. Eighteen of these (90 %) were positive by hemi-nested serotype-specific RT-PCR for DENV1/2/3, with four samples showing evidence of DENV2-3 or DENV1-3 mixed infection. None were ZIKV-positive using NS5 or ENV-based PCR, though weak amplification of a DENV1 NS5 sequence was detected in three serum samples indicating cross-reactivity of the primers. All mosquito samples were ZIKV-negative, whereas 5/8 (63 %) of adult mosquitoes and 11/12 (92 %) of larvae were DENV3-positive.

CONCLUSION:

Both host and vector samples showed absence of ZIKV but high prevalence of DENV. The high rate of infection of larvae with DENV is suggestive of trans-ovarial transmission that could contribute to the surge of human infections during each post-monsoon season. It would be important to guard against false positives using the available Zika-reporting primer sets.

PMID: 29897327 DOI: 10.1099/jmm.0.000769

Keywords: Flavivirus; Mosquitoes; Human; India; Dengue Fever; Zika Virus; Aedes spp.

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Giuseppe Michieli

I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.