The Zika virus belongs to the Flavivirus genus and is very similar to other viruses such as those of dengue, yellow fever, Japanese encephalitis, and West Nile. It was isolated in 1947 in monkeys in Uganda and in 1952 in people in Uganda and Tanzania. Zika virus is generally spread through the bite of an infected mosquito of the genus Aedes, the same one that transmits the virus of yellow fever, dengue and chikungunya, but it can also be transmitted sexually and from mother to fetus. The tiger mosquito (Aedes albopictus), which is present in Italy, could transmit the Zika virus.
In most cases, the infection is asymptomatic. The clinical manifestations of the disease, when present, are generally similar to those of dengue and chikungunya. They are mild symptoms such as fever, rashes (especially maculo-papular), malaise, conjunctivitis, headache, joint and muscle pain, which generally persist for 2-7 days.
Zika virus can be transmitted from a pregnant woman to her fetus during pregnancy (congenital transmission) or near delivery (perinatal transmission). Congenital or intrauterine transmission occurs when a woman contracts Zika virus infection during pregnancy, prior to delivery, and the virus passes to the fetus. One study found that the host immune response may contribute to the pathogenesis ofmicrocephaly. Zika virus is highly neurotropic and can therefore interfere with fetal development either directly, by infecting the brain, or indirectly, by infecting the placenta. Perinatal transmission occurs when a woman contracts Zika virus infection within, approximately, two weeks of delivery and the virus passes to the newborn at or near the time of delivery. When a newborn acquires the infection perinatally, he or she may develop symptomatology characterized by maculopapular erythema, conjunctivitis, arthralgia, and fever.
Zika virus infection, contracted during pregnancy, if transmitted to the fetus can cause in the fetus the congenital Zika virus syndrome, characterized by microcephaly and other congenital malformations, or further pregnancy complications, such as premature birth and miscarriage. Zika virus fever has also been associated with an increased risk of neurological complications in both adults and children, such as Guillain-Barré syndrome, neuropathies and myelitis.
Zika virus infection can be symptomatic or asymptomatic. Most women symptomatic during pregnancy will present with dermal erythema, often maculopapular and itchy. In other cases there will be fever, conjunctivitis, joint pain, headache, muscle pain, and asthenia. These symptoms generally last 2-7 days and are mild and resolve spontaneously. In some cases, skin erythema may persist for 14 days.
It is also important to ascertain possible Zika virus infection in any pregnant woman with Guillain-Barré syndrome or other neurological complications.
The diagnostic investigations recommended for pregnant women are the same as those recommended for the general population. In pregnant women, the virus remains detectable much longer in the blood.
The prevention of risks in pregnancy
.The preventive measures for pregnant women are the same as those recommended for the general population. However, given their importance, it is recommended that health care personnel repeat these recommendations on the application of standard preventive measures at every visit to the mother-to-be. The only way to prevent infection is to avoid being bitten by mosquitoes. Residents or travelers in a country where the virus is present can take protective measures by covering exposed skin with appropriate clothing (long sleeves and long pants) especially during the hours when mosquitoes circulate (dawn to dusk), use repellents, adopt physical barriers (doors, windows, mosquito nets), and stay overnight in places protected by mosquito nets.
They are also the best way to avoid being bitten by mosquitoes.
Particular attention should be paid to people who are unable to protect themselves independently (children, the elderly, the sick).
As a precautionary measure, experts recommend that all women who are pregnant or who do not soon rule out conception should:
- evaluate the possibility of postponing travel programs and plans to countries affected by virus transmission;
- adopt personal protective measures against mosquito bites if travel cannot be postponed;
- give immediate notice of the trip during prenatal visits so that they can be appropriately assessed and monitored returning from trips to risk areas.
There is currently no vaccine available against the virus Zika, so it is important to observe the recommended preventive measures.
In Italy, the spread of the virus is monitored by specific programs, as outlined in the Circular of the Ministry of Health dated February 27, 2019.
Women and men of childbearing age should receive correct information about the possible transmission of Zika virus by sexual transmission and the most appropriate contraceptive methods to prevent it.
In Italy, there is no local transmission of Zika virus. Both women and men returning from a trip or stay in infected areas should practice sexual abstinence or have protected sexual relationships for a period of three months for men and two months for women in order to prevent possible transmission of Zika virus by sexual means.
Partners of pregnant women living in or returning from infected areas should practice sexual abstinence or have protected sex for the duration of the pregnancy.
Women and men who are planning to become pregnant in the near future should avoid traveling to infected countries or areas.
Pregnant women who have been to areas with Zika virus transmission, should inform the attending physician of their travel in order to be appropriately evaluated and monitored.
Pregnant women with a history of travel to affected areas, whether asymptomatic or with a confirmed diagnosis of Zika virus infection, should begin prenatal medical examinations and follow-up early to diagnose any complications and receive appropriate care. Regarding breastfeeding, Zika virus has been detected in breast milk, but there is currently no evidence that the virus is transmitted to infants through breastfeeding. Please note that WHO recommends exclusive breastfeeding for the first six months of life.
Practical recommendations for health workers.
Health workers should exercise caution with regard to women who have traveled to a country with ongoing Zika virus transmission during pregnancy.
It is important during the first natal visit:
- verify recent travel history; .
- evaluate for any Zika virus disease symptoms during travel or the first two weeks after return;
- inform about possible symptoms caused by Zika virus disease and the need to report them immediately if and when they occur;
- inform about the current lack of certainty regarding Zika virus infection and the possible impact on pregnancy.
If the pregnant woman reports symptomatology related to Zika virus disease:
- test for Zika virus infection in the mother
- initiate symptomatic treatment (if necessary) and counseling
If prenatal visit occurs before 18 weeks, consider performing ultrasonography at that time for fetal morphology and week of gestation assessment.
Make the ultrasound for morphology assessment at eighteenth to twentieth week or during the first gynecological visit if it occurs after the twentieth week.
Recommendations for pregnant travelers
.Always refer to a traveler's medicine clinic before traveling for information on whether the Zika virus is present in the country you are to visit.
