Zika virus: causes, symptoms, transmission, treatment and prevention

Zika virus infection is caused by a microorganism of the Flavivirus genus, Flaviviridae family, and is transmitted via mosquitoes, primarily through the bite of the Aedes aegypti mosquito.

The virus was first identified in 1947 in Uganda, in monkeys. Outbreaks of disease caused by this virus have been recorded in Africa, the Americas, Asia, and the Pacific. Between 1960 and 1980, rare and sporadic cases of human infection were discovered in Africa and Asia, usually accompanied by mild illnesses.

The first recorded outbreak of Zika virus disease was reported on Yap Island (Federated States of Micronesia) in 2007. This was followed by a major outbreak of infection in French Polynesia in 2013 and in other countries and territories in the Pacific. In March 2015, Brazil reported an outbreak of disease with skin rashes, shortly identified as a Zika virus infection, and in July 2015, it was found to be associated with Guillain-Barré syndrome.

Mode of transmission

The virus is most often transmitted to humans through the bite of an infected mosquito. Mosquitoes known to be carriers of the virus include two Aedes species, which can be found throughout the world.

When a mosquito bites a person who is already infected with the virus, the mosquito becomes infected and a carrier. Then, when the infected mosquito bites another person, the virus enters the host's bloodstream and causes an infection.

The virus can also be transmitted from person to person through sexual contact. In some cases, the Zika virus has spread from one person to another through blood products (blood transfusion or organ donation). To reduce the risk of spreading through blood transfusions, specialized centers are required to test all blood donations for the Zika virus.

There is evidence regarding the possibility of transplacental transmission of the virus from mother to fetus or during a mother's labor. Transmission is also possible through sexual contact or blood.

There is no information about cases of transmission through saliva, urine, and breast milk.

Symptoms

The incubation period varies between 3–12 days from the bite of an infected mosquito.

In 74-81% of cases, Zika virus infection is asymptomatic.

Symptoms of the disease are usually mild, self-limiting, without severe complications or associated deaths, and with a low hospitalization rate. The main symptoms consist of macular or papular rash, fever, arthralgia, non-purulent conjunctivitis/conjunctival hyperemia, myalgia, and headache.

The maculo-papular rash usually appears first on the face and then spreads to the rest of the body.

The association with Guillain-Barré syndrome and other autoimmune, neurological complications, as well as fetal or neonatal microcephaly in the first two trimesters of pregnancy, were reported during the most recent Zika outbreaks in French Polynesia and Brazil. It has been concluded that there is a strong causal association between these neurological deficiencies and Zika virus infection.

Infection with this virus during pregnancy can cause microcephaly or other fetal problems. Microcephaly is a rare condition characterized by a significantly reduced head circumference compared to the standard average for the same age and sex. Children affected by this pathology most frequently present with developmental disorders.

Diagnosis

The preliminary diagnosis will be based on clinical signs, travel history, or recent activities.

Because the skin rash caused by this virus resembles that of other viral infections, your doctor may request a series of tests to rule out other causes. Blood, urine, and saliva tests can help confirm Zika.

Laboratory diagnosis is based on testing serum/plasma/urine to identify the virus, the virus's nucleic acid, IgM antibodies, or neutralizing antibodies.

Treatment

The resulting disease is, in most cases, relatively mild. Currently, there is no curative or specific treatment for Zika virus. Treatment aims to alleviate symptoms and reduce the risk of complications while the person recovers.

For infected individuals, it is recommended:

• rest and staying at home
• high fluid intake
• administering medication to reduce fever and pain
• avoiding non-steroidal anti-inflammatory drugs and aspirin, except in cases where a doctor has prescribed them

If symptoms worsen, seek additional medical care and advice.

Prevention

Currently, there is no vaccine available for Zika virus that protects against infection.

People intending to travel to endemic countries must take personal protection measures against mosquito bites, both indoors and outdoors, especially from sunrise to sunset, when the vector mosquito's activity interval is at its peak.

Mosquito bites can be prevented by:

• using mosquito nets on windows and doors to reduce contact between mosquitoes and humans
• covering the skin with long-sleeved shirts, pants, and hats
• using repellents recommended by health authorities

Pregnant women should avoid travel to areas where there are outbreaks of this virus. Pregnant women whose sexual partners live in or travel to epidemic areas should protect themselves during sexual contact or not have sexual relations at all for the duration of the pregnancy.

Couples trying to have a baby should postpone conception for a few months if one of the partners has traveled to an endemic area. The Centers for Disease Control and Prevention advises women to wait 2 months and men at least 6 months after possible exposure, even if they have not had symptoms.

References
https://www.healthline.com/health/zika-rash
https://www.who.int/news-room/fact-sheets/detail/zika-virus
https://www.webmd.com/a-to-z-guides/zika-virus-symptoms-prevention
https://www.mayoclinic.org/diseases-conditions/zika-virus/symptoms-causes/syc-20353639
https://www.msdmanuals.com/home/infections/arboviruses-arenaviruses-filoviruses/zika-virus-infection
https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/zika-virus
https://www.webmd.com/a-to-z-guides/zika-virus-symptoms-prevention
https://www.cnscbt.ro/index.php/informatii-utile/473-informatii-pentru-calatori-catre-zone-cu-transmitere-locala-a-virusului-zika-3/file
https://www.cnscbt.ro/index.php/metodologii/infectia-cu-virus-zika/713-metodologie-supraveghere-zika-2017/file