Tuesday, October 26, 2021

Zika Virus: Breaking Down the Facts and What it Means for Mississippians

Zika virus.

By now, I’m certain these words are all too familiar. This virus has taken news outlets, healthcare and governments by storm over the past weeks to months, and rightfully so. We’ve witnessed unprecedented spread of the virus throughout much of Central and South America over a rather short period of time resulting in a pandemic.

While seemingly new on the scene, the Zika virus has been around for decades. This virus was first isolated in 1947 from a monkey in the Zika forest of Uganda. With the help of mosquitos, particularly those of the Aedes genus, the Zika virus spread endemically throughout parts of Africa and Southeast Asia for many years. Not until 2007 was a major Zika virus epidemic observed in humans, when 108 confirmed or probable cases were reported on Yap Island in the Federated States of Micronesia. In addition to the 108 cases observed, approximately 70 percent of the population three years of age and older had evidence of virus exposure but no symptoms. Following the Yap Island outbreak, the Zika virus circulated quietly until 2013 when another epidemic was observed in French Polynesia, this time resulting in over 1,400 confirmed cases of the virus.

Which brings us to the present…

Currently, the largest known Zika virus outbreak is sweeping through Central and South America. While Brazil has seen the most cases (largely innumerable at this time), Zika virus cases have been reported in every country in South America excluding Argentina, Chile, Peru, and Uruguay (as of January 26, 2016). Regarding Central America and Mexico, only Belize, Costa Rica, and Nicaragua have yet to report a case.

Now, before we all head for Tamarindo Beach, I should stress “reported”. It is very likely that virus has been transmitted here but has not been detected/reported. Indeed, the World Health Organization feels strongly that Zika virus will make its way through the Americas, including the United States, possibly sparing only Canada and continental Chile.

But why?

In large part, it comes back to the mosquito. If you’re a Mississippian by birth or by relocation, you’re no stranger to the unofficial bird of the State – the mosquito. These insects serve as excellent reservoirs in which viruses like Zika and Dengue live and multiply. Though the virus is predominantly spread by the Aedes genus of mosquitoes, the unfortunate reality is that this particular genus permeates much of the Americas, including the Southeastern United States. Given this, once travelers bring the virus back to the U.S., native mosquitoes may acquire and transmit the virus resulting a multitude of autochthonous infections and widespread regional cases.

Though that sounds like a doomsday scenario, let’s put Zika virus infection into perspective and look at its potential harms. While the aforementioned outbreaks were tragic occurrences, their ability to teach, inform, and improve patient care should not be underscored. To that end, below are several valuable things we garnered from the Yap Island and French Polynesia epidemics:

1. Zika virus causes MUCH more asymptomatic infections than symptomatic infections. In fact, up to 73 percent of all Yap Island persons screened during the outbreak were found to be asymptomatic carriers. The WHO estimates that approximately 80 percent of all Zika virus infections will not present with any symptoms.

2. Symptomatic Zika virus infection is actually quite mild and resolves on its own. While some cases of neurological disease (Guillan-Barré) were observed, the most commonly encountered symptoms include:

    a. Fever

    b. Headache

    c. Weakness

    d. Muscle aches

    e. Joint aches, notably of the small joints

    f. Rash on the trunk and extremities

    g. Eye pain and/or conjunctivitis

 

3. Zika virus has not resulted in the same hemorrhagic/bleeding conditions as those caused by Dengue virus infection. This is a profound negative finding given the fact that Zika virus is a close relative of the Dengue virus (Flaviviridae family) and shares the same transmission pathway (Aedes spp. mosquitoes). These complications carry a high mortality rate in Dengue infections. Couple that with the rapid and near complete spread of Zika virus, and we likely would be dealing with global crisis.

4. Zika virus results in a short duration of illness. The above symptoms, if apparent, last a few days to 1 week. Zika virus is typically detectable in the blood for two to five days, though it may be possible to detect up to two weeks after symptom onset. This may, in part, explain the short illness. Of note, Zika virus RNA has also been found in the urine of infected patients, though it is uncertain at this time if that is a viable route of transmission. This finding is consistent with other members of the Flaviviridae family (Dengue, West Nile, etc).

5. Zika virus may be spread via sexual transmission. To date, the major case of documented sexual transmission involves spread of the virus from a male to his female partner within 24-48 hours of returning from an epidemic area. Female-to-male transmission has not been documented. If you have returned from an epidemic area, barrier protection is a good idea. For how long? It’s unsure. Virus has been detected in semen for up to three weeks after infection. Though the infection is largely asymptomatic or mildly symptomatic, the long-term outcomes of exposure in the female aren’t clear, particularly as it pertains to subsequent pregnancies.

While the potential for spread to and throughout the U.S. is concerning, at this time, Zika virus infection does not appear to result in profound complications. There is one major caveat to this that should not be taken lightly.

Fetal harm has been well-documented. Pregnant or to-be pregnant mothers should take notice.

A predominant reason for global concern is the impact that the Zika virus appears to have on the fetus, notably fetal abnormalities. Numerous cases of fetal microcephaly (abnormally small head) and fetal intracranial calcifications have been documented during the aforementioned Zika virus outbreaks, including the current South/Central American epidemic. It has been demonstrated that Zika virus can be transmitted from the mother to the fetus, and virus has been found in the amniotic fluid. This doesn’t mean that pregnant individuals are more susceptible to infection; it does mean that Zika virus infections may result in poor outcomes for the fetus when pregnant mothers are infected. Unfortunately, infection and fetal transmission may occur at any point during pregnancy.

Is treatment available?

No. Not yet. Care for an infected patient is supportive and will do nothing to alter the viral course of the infection. Pregnant patients may take acetaminophen for fever if treatment is deemed necessary. Moreover, given the similarities between Zika and Dengue virus, until Dengue infection has been ruled out, patients should avoid using NSAIDS (aspirin, ibuprofen, naproxen, etc) due to risk of worsening hemorrhagic complications. Importantly, pregnant patients should not attempt to self-treat and, prior to initiation of any therapy (prescription or over-the-counter, all patients should consult with their healthcare provider.

What can you do to protect yourself?

No Zika virus vaccine exists, and likely will not exist for at least a year. At this time, travel precautions are the best prevention. The CDC has issued a Level 2 Travel Notice for all travelers venturing to Mexico, the Caribbean, or Central/South America (http://wwwnc.cdc.gov/travel/page/zika-travel-information). While this is not a strict travel ban, it is a strong recommendation to postpone travel to any affected areas, particularly if pregnant. Pregnant patients traveling to these areas should inform their healthcare provider prior to travel and upon return.

In the instance that travel cannot be postponed, all persons should adhere to proper mosquito prevention strategies. Interestingly, the mosquitoes responsible for spreading Zika virus feast almost exclusively during the day. Still, precautions should be followed at all times, indoors or outdoors. These include but may not be limited to:

  • Use of mosquito netting
  • Long sleeves/pants
  • Sleeping indoors in air-conditioned rooms
  • Use of US-EPA certified insect repellants. The most common of these is DEET, which is safe for use during pregnancy, when used according to the product labeling.
  • Treating all clothes with permethrin may also prevent mosquito bites.

 

What if you are bitten by mosquitoes while traveling?

Given that most infections (80 percent) are asymptomatic, you may not notice anything. If you’re pregnant and are bitten by a mosquito(es), consult with your healthcare provider upon return from travel (or earlier if necessary). Of note, the CDC has issued guidance for healthcare workers on how to handle possible Zika virus exposures in pregnant patients. Pregnant patients suspected of being exposed to Zika virus will undergo a screening process for viral RNA in the blood and/or routine ultrasounds. These tests should ideally occur within two weeks of travel.

What else should Mississippians know?

We certainly have the right mosquitoes (Aedes spp.). If the Zika virus finds its way into the U.S., we’re likely to be impacted. One aspect that makes Zika’s impact on Mississippi a bit more difficult to predict is its disease course in persons with sickle cell disease (SCD). The most recent data from the CDC indicates that Mississippi ranks highest in the U.S. for sickle cell disease births per year (34.1 per 1000 births). A single report of Zika virus infection in a sickle cell disease (HbSC) patient in Columbia, South America indicated an increased risk of death in this population. While this single case is thought-provoking, any increased severity in SCD patients is speculative, at best.Mississippi has made great strides in improving infant mortality rates over the prior decade. What impact Zika virus spread may have on those rates or the rates of low/very low birth weight babies remains to be seen.

In summation, while the Zika virus appears daunting and apocalyptic at first glance, the reality is that this virus is quite mild. Certainly, pregnant persons should take great caution in their travel choices. Until the virus reaches the shores of the Southern U.S., routine screening for the virus and/or ultrasounds are unlikely to be of benefit. There are still many things that we do not know about this virus, many of which may come to light in the coming weeks/months. Until then, we must stay vigilant, well-educated, and prepared.

For more information on the Zika Virus outbreak visit:

CDC: http://www.cdc.gov/zika/

WHO: http://www.who.int/mediacentre/factsheets/zika/en/

Mississippi Department of Health: http://www.msdh.state.ms.us/

Healthcare Providers may refer to the below links for:

“Interim Guidelines for Pregnant Women During a Zika Virus Outbreak — United States, 2016”: http://www.cdc.gov/mmwr/volumes/65/wr/mm6503e3.htm

“Questions and Answers for Obstetrical Healthcare Providers: Pregnant Women and Zika Virus Infection”: http://www.cdc.gov/zika/hc-providers/qa-pregnant-women.html


King, Travis_SOP2013 (1)

Samuel Travis King is the assistant professor within the Department of Pharmacy Practice at the University of Mississippi. He also works in the Division of Infectious Diseases at the University of Mississippi Medical Center in Jackson, Mississippi He can be reached at stking@umc.edu.

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