Climate changes as well as various natural anomalies led to the expansion of mosquitoes habitat and, as a result, to a spread of some diseases beyond their typical territories. The last decade was characterized by the outbreak of dengue or West Nile fever in Europe and the US. Nowadays there is an explosive pandemic situation caused by a Zika virus. Its active transmission and medical cases of the disease are registered in 53 countries and regions all over the world, mainly in Asia, Oceania, South and Central America, including the Caribbean. There are well-documented cases of transmission of this disease through a sexual contact in the United States and France. The illness is suspected to have a relationship with Guillain-Barre syndrome and microcephaly in babies born from mothers infected with Zika virus. Growing globalization of trade, traveling and migration contribute to the widespread of Zika virus and make the issue relevant to all countries.
The disease was first discovered accidentally in rhesus monkeys.
This happened in a Zika forest located in Uganda. Scientists and doctors were looking for the causes of yellow fever outbreaks. Then it was unknown whether Zika virus caused any disease in humans. In addition, scientists have recorded the absence of antibodies to the virus in the majority of the inhabitants of Zika forests, while such antibodies were found in residents of other Uganda regions. So Zika virus simply remained ignored for a long time.
The virus was separated in 1948 researching mosquitos Aedes africanus caught in Zika forest.
These small black mosquitos with white stripes on their knees may be found on all continents in tropical and subtropical areas, i.e. in all places with high humidity and warm climate. The disease is transferred from one patient to another through the bite of mosquitoes.
The first description of Zika virus in the scientific literature appeared in 1952. It was first found in 1968 in Nigeria and in the period from 1851 to 1981 there were numerous confirmed facts of the disease in Egypt, Central African Republic, Uganda, Tanzania, Sierra Leone, Gabon and in Asian countries like the Philippines, Malaysia, and India. In 2007 a significant number of patients was recorded on Yap Islands in Pacific ocean. Last year Zika virus was reported to spread in Central and South America. There are two versions that explain the appearance of the virus in the South American continent. According to the first one, it was imported from Africa during the football World Cup, held in Brazil in 2014. Another hypothesis is that the virus appeared in Brazil, the largest South America country, from Micronesia.
Until recently, the very existence of the virus remained quite vague, its spread was limited by the equatorial belt that goes across Africa and Southeast Asia. The scientific literature described less than 15 medical cases. That is why its current pandemic appearance is extremely striking and alarming.
For the first time an outbreak of Zika fever was widely highlighted in 2007 in Micronesia and after that, in 2013-2014 an epidemic happened in French Polynesia and New Caledonia.
In March 2015, Brazil reported about growing number of infectious virus diseases with symptoms typical for dengue and chikungunya fever. An overwhelming majority of blood tests has confirmed an outbreak of these diseases. At the same time, neurologists began to pay attention to the fact that a number of infants with underdeveloped skull and congenital developmental disabilities is constantly growing. In the state of Pernambuco in 2015 dozens of microcephaly cases were registered. In November 2015 a first assumption that Zika virus can cause this disease was put forward.
Scientists explored RNA and antibodies to DENV, CHIKV and WNV viruses in 24 patients who were initially treated for dengue fever. RNA of Zika virus was found in the blood of 7 patients. Interestingly, almost all infected by the virus were young women (86%). Soon the presence of the virus in some patients has been confirmed in other regions of Brazil. Blood tests to detect Zika virus and antibodies against it were performed in rare cases and the disease was diagnosed on the basis of general clinical symptoms and complaints. Therefore, the precise number of people affected by Zika virus is still unknown.
An international panic around Zika disease started after the official statement of the Government of Brazil that the outbreak of the disease is responsible for higher levels of birth defects, namely a microcephaly. In January 2016 the Minister of Health of Brazil suggested that in 270 cases of microcephaly an association with Zika virus or other viral infections is possible. According to the statistics of the country, microcephaly was found in 147 cases earlier in 2014. Since October 2015 microcephaly was mentioned in 4180 cases, though for over 700 cases the diagnosis was rejected.
When the Brazilian government announced more than 4,000 possible cases of microcephaly, a medical circles all over the world got extremely excited and a real panic started by people with no medical education. Pregnant women and those who were planning their pregnancy appeared to be especially worried about the news. Some media, even many professional journals, were full of unproven statements that Zika virus caused a 20 times increase of the microcephaly cases in Brazil. These figures are not only shocking but also made many doctors doubt about the credibility of such information.
Russian media were even actively spreading information that Zika virus emerged as a result of a series of failed genetic modification experiments in 2012. In their reports, they relied on The Mirror magazine, which did not indicate the sources of information. This magazine allegedly said that insects were intentionally created to combat dengue fever and some other diseases. Unfortunately, Zika disease isn’t studied well at the moment and is surrounded by numerous myths and speculations.
Many doctors argue that mosquitoes are only one of the possible ways to spread Zika virus. It may also be transmitted sexually. In 2008, US resident returned home from Senegal, where he had an infectious illness, the symptoms of which coincided with Zika disease. After the return, the presence of blood in sperm was his only complaint. A day after coitus, his wife who never left the US, had all the symptoms of Zika disease. However, sperm samples were not tested to detect the presence of Zika virus.
In 2013 another similar case was described in the medical literature. Tahiti resident had symptoms of Zika disease but visited the doctor worrying about the appearance of blood in sperm after several weeks of illness. Two sperm samples, as well as urine samples, were taken in different days, confirmed the presence of Zika virus RNA, while there was no sign of the virus in the blood at all.
Another case of Zika disease obtained through sexual contact was confirmed in US citizen who returned from Venezuela in January 2016. Scientists confirmed that Zika virus can infect the human reproductive system and breed there, so the transmission of the virus through sexual contact is absolutely possible. Zika virus was also found in the saliva of sick people.
World Health Organization experts think that Zika virus can spread widely in North and South America, affecting all countries except Canada and the continental part of Chile. There are two main reasons for the rapid spread of the virus. The population of North and South America has not faced Zika virus before and therefore has no immunity against it. And, secondly, the mosquito Aedes Africanus is present in all the countries of the region, except Canada and the continental part of Chile. WHO does not exclude that Zika fever can affect 3-4 million people in the world.
A great deal of information about Zika virus that circulates in the media and even in the professional medical publications is mainly unproved and provides more questions than answers. Although plenty of more dangerous and widely spread viral diseases exist nowadays, it’s become fashionable and quite profitable to talk and write about Zika disease, especially when the cries about the terrible virus and a new threat to mankind stem from influential organizations and institutions. Since information is frequently repeated, rewritten and thus distorted, any of us without exception becomes a hostage of a game entitled “terrible diseases that threaten humanity”. Zika disease is practically not explored in a proper way, so there are substantial gaps in our knowledge about the virus and the consequences it causes. These gaps are successfully filled with various myths, assumptions, and groundless fears. As a result, many countries of the world are involved in yet another campaign of struggling against viruses having no understanding of the whole situation.