Zika virus is a mosquito-borne virus that can cause a range of symptoms and is particularly concerning due to its association with severe birth defects.
Discovery and Spread of Zika Virus
The Zika virus was initially identified in 1947 in a Rhesus macaque monkey in Uganda. Following this, evidence of human infection and disease emerged in other African countries throughout the 1950s. From the 1960s through the 1980s, sporadic instances of human infections were detected across both Africa and Asia. The virus gained global attention after significant outbreaks were reported in the Americas in the 2010s, leading to increased research and public health efforts.
How Zika Virus Spreads
Understanding the transmission methods of Zika virus is crucial for prevention.
| Transmission Method | Description |
|---|---|
| Mosquito Bites | The primary mode of transmission is through the bite of infected Aedes species mosquitoes, particularly Aedes aegypti and Aedes albopictus. These mosquitoes are aggressive daytime biters and are also known to transmit dengue, chikungunya, and yellow fever viruses. |
| Sexual Contact | Zika virus can be transmitted from person to person through unprotected sexual contact, even if the infected person does not show symptoms. The virus can persist in semen and vaginal fluids longer than in blood. |
| Mother to Child | A pregnant woman infected with Zika can pass the virus to her fetus during pregnancy or around the time of birth. This vertical transmission is the most concerning, as it can lead to severe health issues for the baby. |
| Blood Transfusion | While less common, transmission through blood transfusions has been reported. Blood screening protocols are often implemented in areas with active Zika transmission to mitigate this risk. |
Symptoms of Zika Virus Infection
Many people infected with Zika virus do not develop symptoms or experience only mild ones. When symptoms do occur, they are typically mild and last for several days to a week. Common symptoms include:
- Fever: Usually a mild fever.
- Rash: Often a maculopapular rash (flat, red spots covered with small bumps) that can be itchy.
- Joint Pain: Often affecting the small joints of the hands and feet.
- Muscle Pain: General body aches.
- Headache: Mild to moderate headaches.
- Conjunctivitis: Red eyes, which can be a distinguishing symptom.
Severe disease requiring hospitalization is uncommon, and fatalities are rare.
Complications of Zika Virus
While the symptoms of Zika are generally mild, the virus is significant because of its potential for severe complications, particularly during pregnancy and in rare neurological conditions.
Congenital Zika Syndrome
The most serious complication is Congenital Zika Syndrome (CZS), which occurs when a pregnant woman transmits the virus to her developing fetus. CZS can lead to a range of severe birth defects, including:
- Microcephaly: A condition where a baby's head is significantly smaller than expected, often indicating underlying brain malformation.
- Severe Brain Defects: Such as smooth brain (lissencephaly), cerebral atrophy, and other structural brain abnormalities.
- Eye Defects: Including macular scarring, optic nerve hypoplasia, and retinal abnormalities.
- Hearing Deficits: Varying degrees of hearing loss.
- Impaired Growth: Often affecting growth before and after birth.
- Joint Deformities: Such as clubfoot.
Guillain-Barré Syndrome (GBS)
Zika infection has also been linked to an increased risk of Guillain-Barré Syndrome (GBS) in adults and, less commonly, in children. GBS is a rare, but serious, autoimmune disorder in which the body's immune system attacks its own nerves. This can lead to muscle weakness and paralysis, which can be temporary or, in severe cases, life-threatening.
Prevention and Management
Currently, there is no specific vaccine or antiviral treatment for Zika virus. Management focuses on relieving symptoms and preventing further transmission.
- Prevent Mosquito Bites:
- Use insect repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone.
- Wear long-sleeved shirts and long pants, especially during the day when Aedes mosquitoes are most active.
- Stay in places with air conditioning or use window and door screens.
- Use mosquito nets if sleeping outdoors or in unscreened areas.
- Eliminate Mosquito Breeding Sites:
- Empty and scrub standing water from containers like buckets, tires, planters, and birdbaths.
- Cover water storage containers.
- Treat standing water that cannot be emptied with larvicides.
- Prevent Sexual Transmission:
- Use condoms consistently and correctly for sexual activity, especially if you or your partner have recently traveled to or live in an area with Zika.
- Consider abstinence during pregnancy if a partner has been exposed to Zika.
- Supportive Care for Symptoms:
- Get plenty of rest.
- Drink fluids to prevent dehydration.
- Take acetaminophen (paracetamol) to relieve fever and pain. Avoid aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) until dengue can be ruled out, as they can increase the risk of bleeding.
Pregnant women and individuals planning pregnancy should consult with their healthcare provider about Zika risks and prevention strategies if they live in or plan to travel to areas where Zika is prevalent.
