What is Zika Fever?
Initially it was isolated in 1947 from a monkey in the Zika forest, Uganda and after that in mosquitoes (Aedes africanus) in the similar forest in 1948; after that it was found in a human in Nigeria in 1952.
Zika virus needs a host to infect people, that host is the mosquito. Humans are mainly infected through the bite of an infected mosquito belonging to the Aedes genus, mostly Aedes aegypti found in the tropical regions. When a mosquito bites a person already infected with the Zika virus, the mosquito contracts the virus and gets infected. These infected mosquitoes can spread the viral infection to other people through bites. These are the same mosquitoes which spread chikungunya, dengue, yellow fever and West Nile virus.
Zika fever is a tropical disease, which is carried from person to person by mosquitoes and has been linked to birth defects in newborns. In Brazil outbreak of microcephaly has been linked to Zika virus. Microcephaly is a neurological condition in which a child is born with a smaller-than-normal sized head and impaired brain development. According to recent reports, Zika virus can be transmitted through sexual intercourse and also through blood transfusion in humans. The Institut Pasteur in French Guiana has sequenced the complete genome of the Zika virus.
The countries currently affected by the virus include, Brazil, South America, Bolivia, Colombia, Paraguay and other tropical countries. It has recently spread to the United States and in Europe such as Denmark and Switzerland.
What are the Causes of Zika Fever?Zika fever is caused by a Zika virus transmitted by Aedes species mosquitoes, which usually bite during mid-morning and late afternoon/evening hours. Aedes includes the following species Aedes aegypti, Aedes africanus, Aedes albopictus, Aedes polynesiensis, Aedes unilineatus, Aedes vittatus and Aedes hensilli.
The mosquitoes lay their eggs in unhygienic and in all stagnant water areas such as flower pots, vases, tree holes, used tyres, open containers, bowels, buckets, etc. They are ferocious daytime biters and stay indoors and outdoors near people.
What are the Symptoms of Zika Fever?The clinical manifestations of Zika fever are similar to those of dengue and chikungunya. The incubation period is generally from 3 to 12 days after being bitten by an infected mosquito and acute symptoms typically resolve within 4 to 7 days with no serious complications and very low possibility of hospitalization.
The following symptoms usually occur about two to seven days after the mosquito vector bite:
- Mild fever (37. 8°C - 38.5°C)
- Exanthema or maculopapular rash, which starts on the face and then spreads throughout the body
- Arthralgia (joint pain), mainly of the small joints of the hands and the feet and swelling in the lower limbs.
- Myalgia (muscle pain)
- Conjunctival hyperaemia (redness of the sclera)
- Asthenia (post-infection) (lack of energy)
- Rarely, retro-orbital pain, gastro-intestinal problems, aphthae (inflammation of the oral mucosa) and pruritus are observed.
- Other symptoms such as headache, malaise, diarrhea, vomiting and dizziness are seen.
It is believed that, but not confirmed that Zika fever can morph into Guillain Barre Syndrome. It is an autoimmune disorder and can cause paralysis, severe pain, loss of bladder control, difficulty breathing and sometimes death.
How do you Diagnose Zika Fever?
- Check with a doctor for any of the above mentioned symptoms providing medical history and travel details especially after travel to areas where Zika virus is prevalent.
- Zika fever is diagnosed based on the symptoms, travel history and after exclusion of more serious diseases such as measles, rubella, chikungunya and dengue (since the symptoms of Zika fever are similar to these diseases).
- The healthcare provider may order blood tests to check for Zika virus which can help confirm the diagnosis. Zika virus has been observed in urine up to 10 days after the appearance of the disease. From the fifth day after the onset of fever, serological investigations using polymerase chain reaction (PCR) can be done by identification of Zika-specific IgM antibodies and verification by neutralization, seroconversion or four-fold antibody titer increase of Zika specific antibodies in paired serum samples.
- Interpretation of serological results should be done in accordance to the vaccination status and recent exposure to different flaviviral infections.
How do you Treat Zika Fever?
- Currently, there are no vaccines or specific anti-viral treatments available for Zika virus infection.
- Symptoms like headache, pain and fever can be treated symptomatically by taking medications such as acetaminophen or paracetamol.
- Pruritic rash is treated with some anti-histamines.
- Patients are advised to take plenty of rest and keep themselves hydrated by drinking lot of fluids.
- Treatment with aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) is generally avoided until dengue is ruled out, because of increased risk of hemorrhage as well as the risk of Reye''s syndrome after viral infection in children.
- If you have Zika viral infection then avoid mosquito bites for first week of illness; because in the first week zika virus is found in the blood and can be transmitted to other people through mosquito bites.
Tips for Infection Control and Prevention
- Since no vaccine or prophylactic drug is available yet for Zika fever, personal protection measures against mosquito bites should be undertaken.
- Use of mosquito repellents is encouraged particularly when there is highest mosquito activity (mid-morning, late afternoon to twilight).
- Drain or discard any sources of stagnant water, which potentially could be mosquito breeding sites, in and around your house.
- Keep the domestic water tanks covered at all times.
- Use of long-sleeved shirts or t-shirts and long pants
- Keep garbage in closed containers and avoid accumulating them.
- Seek your doctor’s advice if you are planning to travel to Zika virus infected areas. This is mostly applicable to young children, pregnant women and people with immune disorders. You should use should use personal preventive measures against mosquito bites if you plan to travel to these places.