What do we know about the ZIKA VIRUS in The Gambia?

Zika virus and pregnancy

Prevention, transmission, diagnose, symptoms, Risk factors, treatments


What is Zika virus infection?

Zika virus infection is caused by the bite of an infected Aedes mosquito, usually causing rash, mild fever, conjunctivitis, and muscle pain.

The virus was isolated for the first time in 1947 in the Zika forest in Uganda. Since then, it has remained mainly in Africa, with small and sporadic outbreaks in Asia. In 2007, a major epidemic was reported on the island of Yap (Micronesia), where nearly 75% of the population was infected.

On 3 March 2014, Chile notified PAHO/WHO of autonomous transmission of Zika virus on Easter Island, where the virus continued to be detected until June 2014.

In May 2015, the public health authorities of Brazil confirmed the transmission of Zika virus in the country’s northeast. Since October 2015, other countries and territories of the Americas have reported the presence of the virus.

What are the symptoms?

The most common symptoms of Zika virus infection are exanthema (skin rash) and mild fever, usually accompanied by conjunctivitis, muscle or joint pain, and general malaise that begins few days after the bite of an infected mosquito.

One out of four infected people develops symptoms of the disease. Among those who do, the disease is usually mild and can last 2-7 days. Symptoms are similar to those of dengue or chikungunya, which are transmitted by the same type of mosquito.

Neurological and autoimmune complications are infrequent, but have been described in the outbreaks in Polynesia, in Brazil and, more recently, in other countries of the region. As the virus spreads in the Americas, giving us more experience with its symptoms and complications, it will be possible to characterize the disease better.

How is Zika virus transmitted?

Zika virus is transmitted to people through the bite of an infected Aedes mosquito. This is the same mosquito that transmits dengue and chikungunya. Recently other modes of transmission have been observed that are described in the following questions.

Can Zika virus be transmitted through donated blood?

Currently there is limited knowledge of Zika virus and the ways it can be transmitted. However, the following suggest it may present a risk to blood safety:

  • The virus has been detected in blood donors in areas where Zika is circulating
  • Transmission of related viruses (dengue, chikungunya and West Nile virus) by blood transfusion has been documented, and thus transmission of Zika virus is possible
  • Brazilian health authorities have reported 2 cases of possible transmission of the virus by blood transfusion.

Studies are needed to assess the prevalence of the virus and of transmission through blood transfusion and blood products to better understand the risk Zika presents.

What precautions should be taken to ensure that the blood supply is safe in countries where

Zika infection is occurring?

  • Organizing blood services well and concentrating processes
  • Implementing quality management programs throughout the transfusion chain and ensuring Good Manufacturing Practices;
  • Ensuring that blood donation is voluntary, repeated, and from low-risk populations, and eliminating mandatory replacement donation;
  • Ensuring the appropriate use of blood and blood products;
  • Providing continuous training for blood services staff and blood products users
  • Providing health surveillance, hem vigilance, and risk management.

Ideally the blood supply during a regional outbreak of Zika should be maintained by increasing blood collections in non-affected areas.

In non-affected areas, consideration may be given to deferring potential donors who have recently visited areas with ongoing transmission of Zika virus infection for 28 days after their departure from these areas.

Can it be transmitted through sexual contact?

The most common form of Zika transmission is through mosquito bites, but the virus has been isolated in semen, and cases of sexual transmission have been observed. Currently the available evidence is being analysed to better understand the public health impact of sexual transmission of Zika.

The IHR Emergency Committee on Zika virus, at its meeting March 8, 2016, said that pregnant women should be advised not travel to areas of ongoing Zika virus outbreaks; pregnant women whose sexual partners live in or travel to areas with Zika virus outbreaks should ensure safe sexual practices or abstain from sex for the duration of their pregnancy.

What can be done to prevent sexual transmission?

All patients (male and female) with Zika virus infection and their sexual partners (particularly pregnant women) should receive information about the potential risks of sexual transmission of Zika virus, contraceptive measures and safer sexual practices, and should be provided with condoms when feasible.

Women who have had unprotected sex and do not wish to become pregnant because of concern with infection with Zika virus, should also have ready access to emergency contraceptive services.

Sexual partners of pregnant women living in or returning from areas where local transmission of Zika virus is known to occur, should use safer sexual practices or abstinence from sexual activity for the duration of the pregnancy.

Can it be transmitted from mother to child?

There is more evidence on this type of transmission. Research is currently under way on the risk of mother-to-child transmission of the virus and its possible effects on babies. Pregnant women in general, and particularly those who develop symptoms of Zika virus infection, should be closely monitored by health providers.

Can mothers with Zika infection breastfeed their baby?

There are currently no documented reports of Zika virus being transmitted to infants through breastfeeding. In countries with ongoing transmission of Zika virus no adverse neurological outcomes or severe diseases have been reported to date from infants with postnatal acquired Zika infection.

Any change to this situation should be carefully monitored.In light of available evidence, the benefits of breastfeeding for the infant and mother outweigh any potential risk of Zika virus transmission through breast milk.

What treatment is there?

Treatment consists of relieving pain, fever, and any other symptom that inconveniences the patient. To prevent dehydration, it is recommended to control the fever, rest, and drink plenty of water. There is no vaccine or specific drug for this virus.

Can it cause death?

In the past, Zika had very limited geographical and demographic distribution, and there was no evidence that it caused death. However, in the current outbreak in the Region of the Americas, cases have been reported of more serious manifestations and complications that have sometimes resulted in death.

Who is at risk of Zika infection?

Anyone not previously exposed to the virus and who lives in an area where the mosquito is present, and where imported or local cases have been reported, may be infected. Since the Aedes mosquito is found throughout the Region (except in continental Chile and Canada), it is likely that outbreaks will occur in other countries that have not yet reported any cases.

How is Zika diagnosed?

Diagnosis is based on clinical symptoms and epidemiological circumstances (such as Zika outbreak in the patient’s area or trips to areas where the virus is circulating).

Blood tests can help to confirm the diagnosis. Some (virological PCR tests) are useful in the first 3-5 days after the onset of symptoms, while others (serological tests) detect the presence of antibodies but are useful only after five days.

Once it has been demonstrated that the virus is present in a given area or territory, confirmation of all cases is not necessary, and laboratory testing will be adjusted to routine virological surveillance of the disease.



What measures should be taken to prevent Zika virus infection?

Prevention involves reducing mosquito populations and avoiding bites, which occur mainly during the day. Eliminating and controlling Aedes aegypti mosquito breeding sites reduces the chances that Zika, chikungunya, and dengue will be transmitted. An integrated response is required, involving action in several areas, including health, education, and the environment.

To eliminate and control the mosquito, it is recommended to:

  • Avoid allowing standing water in outdoor containers (flower pots, bottles, and containers that collect water) so that they do not become mosquito breeding sites.
  • Cover domestic water tanks so that mosquitoes cannot get in.
  • Avoid accumulating garbage: Put it in closed plastic bags and keep it in closed containers.
  • Unblock drains that could accumulate standing water.
  • Use screens and mosquito nets in windows and doors to reduce contact between mosquitoes and people.

To prevent mosquito bites, it is recommended that people who live in areas where there are cases of the disease, as well as travelers and, especially, pregnant women should:

  • Cover exposed skin with long-sleeved shirts, trousers, and hats
  • Use repellents recommended by the health authorities (and apply them as indicated on the label)
  • During the day, sleep under mosquito nets.

People with symptoms of Zika, dengue, or chikungunya should visit a health center.