My take home points from the latest and excellent virology podcast on Zika with Prof. Vincent Racaniello and his guests and his blog notes:
- Where does the name Zika come from? The Zika forest of Uganda.
- When was it discovered? 1947 when it was found to cause an infection in a monkey kept in a cage in the forest by the Rockefeller foundation.
- How long has it affected humans for? Serological studies in the 1950’s show human antibodies against it. Isolated from humans in Nigeria in 1968
- Where is it present? Serologically speaking: Africa (Uganda, Tanzania, Egypt, Central African republic, Sierra Leon, Gabon) and Asia (India, Malaysia, Philippines, Thailand, Vietnam)
- When did it migrate from Africa and Asia? 2007/13 arrived in French Polynesia (South Pacific ocean half way between Australia and the South America). 2014 arrived with the World Cup to South America in 23 countries in S America
- Is the Brazilian virus different? Brazilian virus has an Asian genotype.
- What type of virus is it? Flavivirus – like Yellow fever, Dengue, West Nile and Japanese encephalitis.
- What mosquito carries it? Aedes
- Signs and Symptoms? 75% are asymptomatic. 25%: rash, fever, joint pain, red eyes and headache. Occur 2-10 days after infection. Fatality: rare.
- Is microcephaly a proven association? Not yet
- What is the difference between Colombia and Brazil? High incidence of Zika in Columbia but no microcephaly reported – early or different? Not sure yet.
- Any other fetal damage? Not known.
- Test of choice? Quick serology tests not yet FDA approved. Reverse Transcriptase PCR is the test of choice.
- Are genetically modified mosquitoes released in a part of Brazil to blame? Unlikely, because they were released far away from current high incidence areas in Brazil and mosquitoes cannot fly far. My comment: Eradicating mosquitoes using GM modified mosquitoes – I am not sure if this is amazing or horrifying. Time will tell. Nevertheless the release of GM modified mosquitoes in Brazil is quite a milestone. I wonder what legal framework and environmental checks were put into place to make sure that this experiment did what it was supposed to and not anything else. The TWiV team note that the mosquitoes have a gene which allows them to reproduce when tertacycline is given to them. But they become sterile when there is no tetracycline. The modified gene coding which gives rise to sterility is transmitted to all offspring. The place it was released had a 90% drop in mosquitoes. Does the company Oxitec who GM’ed the mosquitoes know that Doxycycline is used as a prophylaxis against malaria and as a treatment for infection? And that it happens to be a “a broad-spectrum antibiotic of the tetracycline group”? Did they factored this in to their risk assessment? As for these GM mosquitoes being far away, mosquitoes have a bad habit of hitching rides in planes and cars as the cases of ‘airport malaria’ have shown in the UK. I hope the TWiV team are right and the GM mosquitoes are nothing but a conspiracy theorists best friend but it does raise an eyebrow that this fairly innocuous virus to date has started behaving oddly in a country where these GM mosquitoes just happen to be. I also wonder how such an experiment was sanctioned in the first place? How many more GM modified insects are roaming around?
- Is there a window of infection? Not known.
- Could there be another explanation? Yes, blood bone other pathogen, pesticides, water born agent – all unclear.
- Sexually transmitted? The TWiV team not too convinced by the case reports.
- Transmitted versus transmissible – a neat point: the majority of transmission is via mosquitoes but possible sexual transmission is possible.
The Zika update from Professor Vincent Racaniello Ph.D., Professor of Microbiology & Immunology in the College of Physicians and Surgeons of Columbia University and his podcast team. TWiV 375: Zika and you will find This Week in Virology with Vincent Racaniello http://feedproxy.google.com/~r/twivmp3/~5/Q-br7pcccxU/TWiV375.mp3
TWiV is a weekly netcast about viruses - the kind that make you sick. Brought to you by four university professors and a science writer.
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