Like so many people, we here at Dr. Nibber.com are excited for the 2016 Summer Olympic games in Rio De Janeiro, Brazil. Much of the coverage leading up to the games has focused on concerns from athletes, tourists, officials, and the media regarding the Zika virus epidemic that has affected 31 countries and territories since the initial outbreak in 2015. As proponents of the old adage, knowledge is power, we thought it was important to mitigate some of the fear around this issue by providing a breakdown of the virus, how it is transmitted, its impact on your health and what you can do to protect yourself.
What is Zika Virus?
Virus information: The Zika virus is a single stranded RNA virus from the Flavivirus family and is considered an arborvirus (ie. transmitted through mosquitos.) Other viruses found in this family include dengue fever, yellow fever, and West Nile virus.
Epidemiology: While the Zika virus was first identified in 1947 in Uganda, it was largely isolated to mosquitos in this region with limited reports of infection until 2007. Minor outbreaks in 2007, and 2013 were recorded over a 10 week period. In 2014 reports of infections in the Americas identified that the virus had migrated. By February of 2016 an estimated 1.5 million cases were documented in Brazil and 31 countries were affected. Further, officials have detected at least 15 cases of mosquito borne infection in Miami.
Mode of transmission: Humans became unintentional hosts for this virus that was normally transmitted between non-human primates and the Aedas aegypti mosquito common to central and eastern Africa as well as parts of Asia. However, since infection migrated outside of Africa new modes of infection are arising:
a) Mosquito bites: from Aedas aegypti mosquito bites which tend to bite more frequently during the day and lay eggs near standing water.
b) Sexual transmission: Male-female: In all cases male patient was symptomatic and the virus was detectable in semen. Though new cases are emerging suggesting transmissibility before or after symptoms become apparent. Female-Male: No documented cases. Male-Male: Have been reported by the CDC in April 2016.
c) Transplacental/perinatal transmission: Infected pregnant women can transmit the Zika virus to their fetuses with significant health consequences and are thus considered the most vulnerable population.
d) Blood Products: Some blood donors were found to be positive for Zika virus despite the fact that they were asymptomatic at the time of donation.
S/Sx of Infection: Upon transmission the virus incubates for 3-12 days before exhibiting mild to moderate symptoms, if any. These symptoms typically persist between 2-7 days and resolve on their own. These symptoms typically include a fever, muscle or joint pain, headaches, a diffuse rash, upset stomach, red and itchy eyes, and swelling.
This all may sound benign however the there are some very serious complications that can arise from infection. First, as we mentioned earlier women who are pregnant or planning on becoming pregnant are vulnerable due to the fact that the Zika virus infects neural progenitor cells in growing fetuses inhibiting their growth resulting in the microcephaly. Other fetal complications and congenital anomalies have also been reported directly correlated with the outbreak of Zika virus. A study of brazilian women found that 29% of infected mothers conferred fetal abnormalities such as abnormal amniotic fluid, central nervous system lesions, and growth restrictions. Though as more cases arise it may become clear what the actual risk of fetal abnormalities in infected mothers is. Further, women who are not pregnant but intend on becoming pregnant may still be at risk as males are considered to be at risk for transmitting the Zika virus to their partner 2-10 weeks after initial symptom onset.
Another serious sequelae of Zika virus infection is Guillain-Barre Syndrome (GBS), a nerve conduction concerns resulting in muscle weakness and even paralysis. The Zika virus has been associated with an increased incidence of GBS, though not all infected individuals will develop GBS.
What can you do?
The CDC has created clear recommendations focusing on prevention including travel advisories, tips on how to remove mosquito reservoirs, and guidelines relating to safe sexual practices. For example it is recommended that infected men should avoid intercourse or ensure proper use of condoms for six months. While asymptomatic males who have travelled to high risk areas have been told to use condoms for 28 days following travel. Guidelines for blood donation suggest asymptomatic individuals who are at risk for infection (risk= s/sx within four weeks, sexual contact with individuals who traveled in epidemic regions for three months, self travel in risk area within four weeks) should postpone donations for four weeks.
While DEET (an active ingredient) has been long considered the most effective repellent, there is an increasing demand for alternative natural biopesticides. While none have been shown to be as effective as DEET there are some promising alternatives that may be used to repel mosquitos for medium to low risk individuals. For example, essential oils extracted from Echinophora leaves, Juniperus communis, and cupressaceae exhibited some toxicity in various species of mosquitos. However, a study in 2015, found that essential oils of Curcuma Longa were beneficial in the same mosquito that is a vector for Zika virus (Aedas aegypti) showing high biting deterrent activity comparable to DEET.
As more epidemiological and microbiological information becomes available regarding this virus our guidelines will evolve. As new statistics and science emerges we will be better equipped to combat and prevent adverse sequelae of infection.
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