Zika Virus: A New Viral Threat

After the world has only recently recovered from the Ebola epidemic, it seems another virus is storming across the globe. In the past few days, Zika virus has become a very real threat, with the World Health Organization declaring it to be a global emergency1. If this is the first you're hearing of the virus, let's go over some of the basics and why some people are very concerned about its spread.
Batman Begins. Warner Bros.
The Zika virus is not a newly found virus. It was actually discovered in 1947, when scientists, who were studying yellow fever at the time, found a rhesus monkey in the Zika Forest in Uganda. Zika means “overgrown” in the Luganda language. This monkey went on to develop a fever and following isolation of its serum, scientists found Zika virus for the first time. It was isolated from a human in 19522. While it originated in Africa, Zika virus has recently had an “explosive spread” to Latin American and South Asian countries.
Zika distribution map. Image from the CDC.
Typically, only 1 in 5 people will demonstrate symptoms, which include3:
  • Fever
  • Rash
  • Joint/muscle pain
  • Red eyes

Hospitalization or death is rare in adults. These symptoms last 2-7 days and are similar to Dengue and Chikungunya diseases, which also happen to be transmitted by mosquitoes like Aegis aegypti. This mosquito operates mainly during daylight hours, which is a factor to consider since bed nets won't be as protective in comparison to diseases like malaria (whose mosquito vector is of a different species and bites primarily at night). As far as transmission from person to person, mothers, in rare instances, may pass the virus on to their newborn child. Some cases of sexual contact and blood transfusions have been reported to pass the virus on as well3. However, Zika virus cannot be transmitted via aerosols, so that at least is good news.

Mosquitos can transmit a variety of diseases. A Bug’s Life. Walt Disney Pictures.
If only one in five people actually demonstrate symptoms and they don't seem overtly serious, then why is there such concern over this virus? The answer lies in newborn babies. Unfortunately, Zika virus has been directly linked to microcephaly. Microcephaly is a rare neurological condition where an infant's head is significantly smaller than the average child's, which causes disturbances or delays in motor functions and speech progression. Mental disabilities and hyperactivity are also common symptoms of microcephaly.
An example of microcephaly.
Zika virus first began to be linked to microcephaly when a sudden burst of cases were reported in August of 2015 in Brazil. Whereas hospitals would normally go months without seeing a microcephaly case, they were now having several cases a day. Some of the mothers reported having a rash during early pregnancy (which could point to Dengue, Zika, or Chikungunya). To date, Brazil suspects there are over 3500 cases of microcephaly (but not all may be a direct result of the Zika virus)4.

There is no cure for the Zika virus, and developing a vaccine could take quite a while, as Dengue just had its own vaccine released after 20 years of development. Despite this, several pharmaceutical companies are working on a possible vaccine. Testing for the detection of Zika virus is also difficult since it bears so many similarities to Dengue and Chikungunya in both symptoms and genetic makeup. PCR is commonly used to detect Zika, but it must be detected within the short timeframe (2-7 days) that it appears in the blood.

Despite the beauty that can be observed in Brazil, pregnant women should stay away for now.
Brazil itself has advised that women avoid getting pregnant at this time. Other countries are suggesting pregnant women avoid traveling to affected areas, which is particularly important for a country like Brazil since the Olympics are only six months away. Locally, the first documented case of microcephaly (associated with Zika virus) was found in Hawaii recently5. And, there was also confirmed sexual transmission of Zika in Texas6. There have been 31 reported cases of Zika in the USA, all associated with travel to infected areas. For now, these affected countries are ramping up efforts in reducing breeding grounds for mosquitos by dumping still water and fumigating regularly. What was once thought to be a Dengue outbreak now has greater fears as cases of Zika are being uncovered.

If you have any comments, you can contact tech@biolegend.com. For the latest information, however, check the CDC and WHO webpages.


Just when I thought I got the hang of science…Comic by Pedromics.

References:
  1. Zika-linked conidition: WHO declares global emergency
  2. Zika virus. I. Isolations and serological specificity
  3. CDC Zika homepage
  4. How Brazil uncovered the possible connection between Zika and Microcephaly
  5. Hawaii baby born with small head had prior Zika infection
  6. Zika has been sexually transmitted in Texas, CDC confirms

Contributed by Ken Lau, PhD.
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