Background
Zika virus is one of the members of the so-called Flavivirus virus family and is spread through mosquitos. The virus’s effect lasts from several days to a week. Although it was discovered in Uganda as early as 1947 and is quite common in Africa and Asia, the pathogen was infrequent in the western hemisphere until May 2015, when an outbreak occurred in Brazil. The Zika virus was first discovered in a rhesus monkey that lived in the forest near Lake Victoria in 1947. A year later, the causative agent of fever was isolated from a mosquito of Aedes Africanus mosquito. In 1952, cases of human infection were recorded in Uganda and Tanzania.
Since then, episodic outbreaks of infection have been reported in Africa and South and Southeast Asia. The first detailed description of its clinical manifestations was made in 1964. Epidemiological studies have found antibodies to the virus in the blood of orangutans, zebras, elephants, buffaloes, and rodents. In 2007, the virus penetrated the Pacific island of Yap, where up to 75% of the population became infected.
Six years later, an outbreak of infection was recorded in French Polynesia (about 11% of the population, or 28,000 people were ill), during which possible neurological complications of the disease were noted. In March 2014, Chilean authorities reported an outbreak on Easter Island that lasted until June. In May 2015, the the virus was recorded to spread in northeastern Brazil. After that, the epidemic quickly covered neighboring countries. Soon, reports identified an increased incidence of microcephaly in babies born to women contracted Zika virus when being pregnancy.
In less than a year, more than 4,000 such newborns were identified in Brazil. Before that, an average of 163 cases of this congenital anomaly was recorded annually. Further, Colombia and El Salvador also reported increased cases of microcephaly. The seemingly harmless infection has become a cause of international concern. (Liu et al., 2019). Until now, almost no inhabitant of the western hemisphere of the planet has been infected.
Therefore, only a tiny part of the population was immune to the virus, which caused it to spread rapidly. Millions of people can be infected in tropical regions of the Americas. However, the infection does not cause symptoms for most people and does not lead to long-term effects (Liu et al., 2019). The scientific and medical concern is focused on women who become infected during pregnancy and those patients who end up with a temporary form of paralysis after being exposed to the Zika virus.
Active agent and factor of Spreading
Only female mosquitoes bite people since they need blood to lay their eggs. They suck in the virus along with the blood, and it travels from the intestines through the circulatory system to the salivary glands. Mosquito saliva contains a high level of proteins that prevent blood from clotting. When a mosquito bites a person, its saliva is injected, so that blood does not clot in its proboscis. Together with saliva, a virus enters the human body and starts spreading. This virus is distributed via a particular mosquito known as Aedes and typically breeds in small water sources. They are usually active and bite people during the daytime. In most cases, the Zika virus is transmitted through the yellow fever mosquito, Aedes aegypti (Liu et al., 2019). Aedes albopictus mosquitoes (also called the Asian tiger) can also send the virus, but it is currently unknown how effectively they do this.
Symptoms
The disease can cause the development of fever, skin rash, joint pain, conjunctivitis, muscle, and headache, less often – discomfort in the digestive tract, vomiting. However, most of the patients are unaware that they have contracted the Zika virus. According to the representative of the American Society of Infectious Diseases (USA), Amesh Adalya, only about one in five infected people experience any symptoms, and most people do not have any symptoms at all. She also says the virus rarely causes severe complications, and until now, has not been considered a severe infectious disease at all. In rare cases, the Zika virus is associated with the development of Guillain-Baret syndrome (Musso et al., 2019). Reports indicate that the infection results in partial or complete paralysis, however, primarily temporary (Savage et al., 2016). In addition, it is noteworthy that in recent years in South America, particularly in French Polynesia and Brazil, reported cases are growing due to occurring epidemics.
Risk Category: Pregnant Women
Like most viruses, the Zika infection significantly threatens pregnant women, especially during the first trimester. Facts confirm the infection of the fetus by a sick mother. In this case, the pathogen can enter the placenta and infect the fetus. It can also cause microcephaly and other fetal malformations, such as defects in vision and hearing, slow weight gain (Musso et al., 2019). Microcephaly is a severe malformation of the fetus, in which its brain does not develop properly, which in the future threatens mental retardation and neurological pathologies.
Generally, it is rather difficult to establish a connection between ZIKV and microcephaly due to several circumstances. First, how many pregnancies were affected by the virus remains unclear – the infection is often asymptomatic. Secondly, there is still no clear definition of microcephaly, which makes it difficult to establish a reliable link between the virus and microcephaly. (Musso et al., 2019) Third, other infectious agents cause microcephaly: cytomegalovirus and Rubella virus.
Nevertheless, based on the findings of the Zika virus present in the amniotic fluid as well as the brain of microcephalic embryos, the CDC in April 2016 established a link between ZIKV and microcephaly. Later, this conclusion was confirmed by experimental work on mice, which showed that the virus quickly penetrates the placenta and affects the embryo’s stem cells. However, some children whose mothers had the Zika virus during pregnancy are stillborn completely healthy. Therefore, more cutting-edge studies are needed to clearly.
Recommendation: Preventing Zika Virus Infection
Despite the long discovering of the virus, there is still a lack of vaccines for this type of Flaviviruses. Therefore, it is recommended to avoid mosquito bites, as insect bites are a pith of infection. It is also recommended to use clothing that fully covers parts of the human body, uses special nets where mosquitoes can enter the house, and prevents water pools where insects can breed. In some cases, a solution could be using a mosquito net over the bed. This is generally advised for women traveling to countries at risk of contracting the Zika virus. When choosing repellents, it is better to buy products with diethyltoluamide, picaridin, and IR335 (Musso et al., 2019). Products containing lemon eucalyptus oil and paramethanediol can also provide long-term protection. It is recommended to apply the repellent after using sunscreen, dressing on clothes treated with permethrin.
Moreover, the use of insect repellent underclothing is proved to be efficient in preventing the infection. One should always read the instructions for each specific product. In case of disease, the infected person is recommended to avoid mosquitos within the first week. The virus can spread from person to mosquito through blood, increasing the risk of spreading to other people (Musso et al., 2019). Since the Zika virus can be transmitted sexually from a man to his partner, it is recommended to use condoms during and after travel to countries affected by the disease.
References
Liu, Z. Y., Shi, W. F., & Qin, C. F. (2019). The evolution of the Zika virus from Asia to the Americas. Nature Reviews Microbiology, 17(3), 131–139.
Musso, D., Ko, A. I., & Baud, D. (2019). Zika Virus Infection — After the Pandemic. New England Journal of Medicine, 381(15), 1444–1457.
Savage, C. L., Savage, C., Kub, J. E., Kub, J. E., & Groves, S. L. (2016). Public health science and nursing practice. F.A. Davis Company.