What is Zika Virus :
Zika is a mosquito borne flavivirus which is spread by mosquito bite of Aedes Africanus mosquitoes which are usually active during day time.It was first identified in 1947 from monkey in Zik Forest of Uganda. Zika means “Overgrown” in local language of Uganda. This monkey developed a fever and researchers isolated from its serum a transmissible agent that was first described as zika virus in 1952. Thereafter, in May 2015 almost 13,00,000 people in Brazil were infected by it and then throughout America. WHO has recently confirmed 3 cases of Zika Virus in Ahmedabad, Gujarat, India and is rapidly spreading.. Neither an effective treatment nor a vaccine is available ; therefore, the Public health primarily focuses on preventing infection, particularly in pregnant women.
Like other flaviviruses, it is transmitted by mosquitoes, primarily by Aedes Genus which are widely distributed globally. Mosquito acquisition of the virus occurs during a blood meal; after uptake, the virus replicates and is transmitted to reservoir animal at the next blood meal.
Apart from mosquito bite, it is also transmitted from men and women to their sexual partners. It is advised that people who have travelled Zika affected area should use condoms for at least six months after their travel as the virus is still transmissible even if symptoms does not persists.
It can also be spread from Mother to Child during pregnancy or at delivery. Although Zika is not a fatal disease but the real reason behind the panic is for the women who are pregnant. Zika is found to be a major cause of microcephaly – a birth defect due to which children are born with visibly smaller heads, severely limiting their mental and physical abilities. It may also cause other neurological disorders such as Guillain-Barre syndrome.
It is also spreaded through blood transfusion and therefore, screening of blood donors is necessary. High Risk donors should be deferred for atleast 4 weeks.
Zika Virus Symptoms :
In humans, the incubation period from mosquito bite to Zika Virus symptom onset is 3-12 days. When Zika Virus symptom occur, they are typically mild, self-limiting and non specific having similarity to dengue & chicken gunya. Commonly reported Zika Virus symptoms include rash, fever, arthralgia, myalgia, fatigue, headache and conjunctivitis. Rash is a prominent feature. Fever is typically low grade (37.4°C –38.0°C) . Zika Virus Symptoms generally resolve within 2 weeks.
The first well documented case was found in 1964 where Zika Virus Symptoms appeared to have a beginning with a mild headache and progressing to a maculopapular rash, fever and back pain. Within 2 days, the rash was fading, and within 3 days the fever was gone and only the rash remained. Therefore, the most common Zika virus Symptoms is mild fever, rash, conjunctivitis, headaches and arthralgia which appears between 3 to 12 days after the mosquito bite. However, one out of four patients may not develop any Zika Virus Symptoms. Zika Virus Symptoms also includes muscle pain , pain behind the eyes and vomiting.
Zika Virus Testing :
There are two ways of Zika Virus Testing through urine and blood test :
- Zika Virus Testing through Virus Detection :
It can be identified by RT-PCR in ill patients who have onset of fever from day 5 by serology through detection of specific antibodies. Serological cross-reactions with closely related flaviviruses with closely related flaviviruses such as Dengue fever are possible.
- Zika Virus Testing through Antibody Detection :
ZIKV specific IgM antibodies can be detected by ELISA or immunofluorescence assays in serum specimens from day 5 after the onset of symptoms. Since a single serum in the acute phase is presumptive, it is recommended by the WHO that a second sample be taken 1-2 weeks after the first sample to demonstrate seroconversion (negative to positive) or a fourfold increase on the antibody titer( with a quantitative test).
Zika Virus Treatment :
No specific Zika Virus treatment or vaccine is available for its infection. Management is supportive and includes rest, fluids, antipyretics, and analgesics. Aspirin and other non-steroidal anti-inflammatory drugs should be avoided until dengue is excluded because of the risk for hemorrhage among dengue patients. While there is no specific Zika Virus treatment, paracetamol (acetaminophen) and rest may help with the symptoms.
Zika Virus Prevention :
In absence of any specific Treatment or Vaccine, everyone should take precautions in the areas with risk of zika as it will help stop the overall spread of the virus. It is particularly very important for pregnant women to protect themselves from mosquitoes. In short, Zika virus is an irreversible problem. If you get exposed, there are no treatments or any vaccines to prevent you from getting zika. Following are the measure which can be taken to prevent yourself :
- Use condom for atleast 6 months if you get physically involved with partner who have travelled virus affected area. Sex includes oral, vaginal, anal sex or sharing sex toys.
- Use Permethrin-treated clothing and outdoor gear such as boots, pants, socks and tents. You can buy pre treated clothings and gear or treat them yourself. Wear long pants, light colored clothing, insect repellants & bed nets.
- Use mosquito net if you are where you are sleeping is exposed to the outdoors.
- Stay and sleep in screened –in or air conditioned rooms.
- Chalk out community level strategies to target mosquito breeding through elimination of potential egg-laying sites (potted plant saucers, water storage units, used tires) by drying wet environments or using insecticide treatment.
- Pregnant women residing in countries that are not Zika Virus endemic are advised against travel to affected countries. Testing should be offered to all pregnant women who have traveled to areas with on going Zika Virus Transmission. Serial fetal ultrasounds should be considered to monitor fetal anatomy and growth every 3-4 weeks in pregnant women with positive or inconclusive Zika Virus testing results, and the infact should be tested at birth.
- Men who reside in or have travelled to an area of active Zika Virus transmission and who have a pregnant partner should abstain from sexual activity or use condoms during sex. Similar guidelines apply for men with a non pregnant female sex partner who is concerned about sexual transmission of Zika Virus.
Zika Virus Vaccines:
Till date there is no vaccine or treatment for this situation. The World Health Orgniztion (WHO) has suggested that priority should be given to develop inactivated vaccines and other non-live vaccines, which are safe to use in pregnant women. Almost 18 companies and institutions worldwide are developing vaccines but as per reports available, such vaccines are unlikely to be widely available for next 10 years.
Recently in June 2016, FDA has granted the first approval for a human clinical trial for Vaccines which was later in March 2017, was approved for Phase 2 clinical trials. This vaccine consists of small circular piece of DNA, known as a plasmid, that expresses the genes for the Zika Virus envelope proteins. As the vaccine does not contain the full sequence of the virus, it cannot cause infection. The WHO has said no vaccine is likely to be available until 2020.
When to see a doctor
See your doctor if you think you or a family member may have Zika virus, especially if you have recently traveled to an area where there’s an ongoing outbreak. Public Health Clinics has blood tests to look for Zika virus or similar diseases such as dengue or chikungunya viruses, which are spread by the same type of mosquitoes.