Tuesday, February 02, 2016

Thailand Reports `1st' Domestic Case Of Zika

UPDATED (see bottom)


Thailand is one of several Southeast Asian nations where Zika has been suspected to be circulating, but due to the background noise from Dengue and Chikungunya, and a lack of Zika-specific testing, it has never been proven.

At least, not until today. 

First a report from AFP, then I'll be back with more.

A man has contracted the Zika virus in Thailand, officials said Tuesday, as a global alert intensifies over the mosquito-borne infection blamed for a surge in serious birth defects in South America.

Authorities said the 22-year-old Thai man is likely to have caught the same strain of the virus that has caused panic in countries such as Brazil and Colombia.

The Zika status of countries like Vietnam, Laos, Cambodia, and even China are suspect because the testing routinely done for dengue can show positive results for Zika as well.  

As more specific PCR testing for Zika becomes widely available it is likely the list of countries where autochthonous transmission takes place will rise considerably. 

One clue that Zika might have been in Thailand prior to today's report came from a 2014 case report from the American Journal of Tropical Medicine and Hygiene that described a Canadian tourist who returned from Thailand and was subsequently diagnosed with Zika. 

First Case of Zika Virus Infection in a Returning Canadian Traveler


A woman who recently traveled to Thailand came to a local emergency department with a fever and papular rash. She was tested for measles, malaria, and dengue. Positive finding for IgM antibody against dengue and a failure to seroconvert for IgG against dengue for multiple blood samples suggested an alternate flavivirus etiology. Amplification of a conserved region of the non-structural protein 5 gene of the genus Flavivirus yielded a polymerase chain reaction product with a matching sequence of 99% identity with Zika virus. A urine sample and a nasopharygeal swab specimen obtained for the measles investigation were also positive for this virus by reverse transcription polymerase chain reaction. Subsequently, the urine sample yielded a Zika virus isolate in cell culture. This case report describes a number of novel clinical and laboratory findings, the first documentation of this virus in Canada, and the second documentation from this region in Thailand.

Since arboviruses are best transported over long distances by viremic humans on holiday, popular tourist destinations like Brazil, Thailand, and the Islands of the Caribbean - which all feature abundant mosquito vectors - seem to be natural hot spots for Zika and CHKV.

A notion that, as a Floridian, already has me stocking up on DEET for the summer ahead.


Although the media reports are calling this the first domestic case of Zika in Thailand, I was alerted by Gert van der Hoek of Flutrackers to a recent study (also in Am J Trop Med Hyg where 7 Zika cases were confirmed in Thailand between 2012-2014. 

Detection of Zika Virus Infection in Thailand, 2012–2014


Zika virus (ZIKV) is an emerging mosquito-borne pathogen with reported cases in Africa, Asia, and large outbreaks in the Pacific. No autochthonous ZIKV infections have been confirmed in Thailand. However, there have been several cases reported in travelers returning from Thailand.
Here we report seven cases of acute ZIKV infection in Thai residents across the country confirmed by molecular or serological testing including sequence data. These endemic cases, combined with previous reports in travelers, provide evidence that ZIKV is widespread throughout Thailand.


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