Zika Virus: In 40 Mosquitoes Around The World

25. January 2016
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For many years Zika virus slumbered away in solitude, little noticed by science. Now it's rushing from country to country. Its harmlessness as described earlier is also something it has left in the past. It's time for its re-evaluation.

Senegal, 2008. Brian Foy and Kevin Kobylinski, entomologists at Colorado State University, did not know what hit them. After a research trip they suffered from swollen joints, headaches and rashes. The symptoms didn’t match any known viral infection – mainly due to its mild nature. A year later Foy and Kobylinski randomly met Andrew Haddow, who does research as a virologist at the University of Texas. He worked his way through Zika virons and found matching antibodies in his patients’ blood. According to Haddow there had for 50 years in Africa been sporadic outbreaks of the disease, without the scientific world having found great interest in it.

Off to new shores

Meanwhile, the situation has fundamentally changed. Over the last eight years in South-east Asia and the Pacific Islands more and more patients have fallen ill. According to health authorities in French Polynesia, in 2013 and 2014 some 30,000 people were affected, ie one in ten residents. Thanks to the FIFA World Cup which ran from 12 June to 13 July in 2014 the said pathogen also made its way to Brazil [Paywall]. In mid-May 2015 the Ministry of Health confirmed suspected cases from several provinces in the country. In July there was talk of 40 laboratory-confirmed cases, in early December of as many as 739. Zika viruses shortly thereafter conquered Colombia and Panama. In early November there were already 110 confirmed infections. Duane Gubler, head of the “Program on Emerging Infectious Diseases” at Duke University National University of Singapore expects outbreaks sooner or later in the southern US and in Southern Europe.

Small and mean

He argues this based on the spread of the Aedes mosquito, the main vector of Zika viruses. The pathogen itself is similar to better-known flaviviruses such as dengue fever, West Nile fever, yellow fever and Japan B encephalitis virus. After an incubation period of twelve days patients suffer from head and joint aches, fever, chills and a general feeling of illness. Typical symptoms also include maculo-papular rashes and conjunctivitis. The infection often subside by itself; many cases are asymptomatic.

Yet appearances can be deceptive. In Brazil, cases of congenital microcephaly among unborn babies are accumulating. Scientists suspect a link between infections during pregnancy and malformations of the central nervous system. In multiple instances they found when examining the blood and tissue of babies Zika virus indicators. From the perspective of the European Centre for Disease Prevention and Control (ECDC) there is a lack of evidence; however causality here is considered quite likely. Authorities do not want to wait until clarification arrives on this matter. They have now sent 25,000 soldiers to the north-east of Brazil in order to decimate Aedes aegypti. Whether the measure brings great success is something that raises doubts. Each puddle, every pond, every old car tire with water is a breeding ground for such pests. Researchers are working on transgenic, sterile mosquitoes or are trying to suppress the tranfer of virus using Wolbachia bacteria. It could take a while.

Learning more

Mosquitoes are in any case only a part of the problem, as evidenced by further studies. Didier Musso, a virologist at the Louis Malardé Institute, Tahiti, examined 593 samples from blood donors. Using ELISA he found in 80 percent of all tests antibodies against dengue virus, Zika virus, the Japan B encephalitis virus or West Nile Virus. Doctors are now urging the thorough monitoring of transfusion medicine in the countries concerned and further investigation of transmission pathways. Musso found out in some individual cases infection occurred after unprotected intercourse. Researchers managed to detect virus in semen. They are entering new territory, as PubMed searches can show. By mid-December there were only 214 publications present for “Zika” whereas for “dengue” there were 14,700. In order to identify all new infections statistically, WHO experts have decided to use an ICD-10 code normally reserved for emergencies. From here on U06 signifies Zika virus disease and U06.9 signifies “Zika virus disease, unspecified”. Until such time as a revocation arrives, this will remain in effect for both ICD10-WHO as well as for ICD-10-GM. Background information: The World Health Organisation according to a statement does not rate HIV, tuberculosis, malaria, influenza virus or dengue as the biggest risks from an epidemiological perspective, but rather Ebola and Marburg fever, MERS, SARS and Zika fever. All pathogens have the potential at any time to trigger further epidemics, virologists write. Travellers should include known protective measures such as light-coloured, body-covering clothing and repellents containing diethyl toluamide (DEET) in their packs. Vaccines are not yet currently available. Pregnant women are only left with the option of avoiding the affected regions – wherever possible.

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2 comments:

MBBS khawar abbas
MBBS khawar abbas

Thanks for such informative writing

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Dr. med. Essam Elmisherghi
Dr. med. Essam Elmisherghi

Thank you , realy intersting article. Dr.Essam Elmisherghi from Libya

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