 Brazil's Zika outbreak may be far worse than had previously been believed, the country's top health official claimed on February 1, because the vast majority of infected people do not show any symptoms. Zika is a mosquito-borne virus that has recently begun spreading through Latin America for the first time. Some researchers claim that it may be linked to thousands of new cases of a congenital condition called microcephaly in Brazil, although very few microcephaly cases have actually shown any trace of the virus. Concern over the possibility that Zika infection of pregnant women may be causing microcephaly has caused the World Health Organization to declare the Latin American Zika outbreak a global emergency. Microcephaly is characterized by an abnormally small head and, often, underdeveloped brains. In 90 percent of cases, microcephaly results in hampered physical and mental development. Scale of outbreak unknown The Zika virus was first identified in Africa in 1947, but was utterly unknown in the Americas until it struck Brazil in May 2015. The Brazilian government believes that it probably reached the continent when an infected visitor came to Brazil for the 2014 World Cup. That person was bitten by a mosquito, which then contracted and began spreading the virus. Once enough people were infected, the larger mosquito population also became infected, which is probably enough to allow the virus to become endemic. According to the Pan-American Health Organization, Zika has already spread from Brazil to 24 other countries and territories in the Western Hemisphere, including Colombia, where there have been over 3,100 cases of pregnant women with Zika virus without a single confirmed case of microcephaly. Evidence now suggests that the spread of the virus may have been accelerated by the irresponsible release of genetically modified mosquitoes, which ended up boosting rather than depleting the population of the animals that carry the virus. Since the outbreak started, Brazil has seen a total of 3,700 suspected and has confirmed new microcephaly cases in a trend that actually predates the virus 'epidemic.' According to Health Minister Marcelo Castro, Brazilian medical experts are claiming that microcephaly is being caused by the Zika virus infecting pregnant mothers; Castro has also contradicted health experts' claims that the virus can be transmitted from person to person, through bodily fluids such as semen. 'The microcephaly cases are increasing by the week and we do not have an estimate of how many there will be,' Castro said. 'The situation is serious and worrying.' The fact that so many cases are asymptomatic makes it harder to get a grasp on just how bad the outbreak is, he warned. 'Eighty percent of the people infected by Zika do not develop significant symptoms,' Castro said. 'A large number of people have the virus with no symptoms, so the situation is more serious [than] we can imagine.' Brazil mobilizes military, vaccine makers Brazil is resorting to extreme measures in an effort to get a handle on the virus. Local governments are now required to report all Zika cases to the central government, and nearly all states now have labs equipped to test for the virus. By March, the government expects those labs to also be able to test for dengue and chikungunya, which are transmitted by the same mosquito. These tests will only be effective within five days of infection, however. In addition, President Dilma Rousseff has signed a temporary decree requiring all Brazilian residents to allow government officials to inspect their properties and homes to make sure they have no sources of standing water that could allow mosquitoes to breed. The government will be sending tens of thousands of soldiers door-to-door as part of this effort. Brazil has also announced plans to prohibit people who have ever had Zika from donating blood. Researchers from Brazil have also partnered with U.S. scientists in a fast-tracked effort to develop a Zika vaccine. The scientists are planning to genetically modify the virus used in a (still experimental) dengue vaccine. In spite of all its alarmist language about the outbreak, the Brazilian government insists that there is no reason to cancel or relocate the 2016 Olympic Games, planned for Rio de Janeiro in August. 'We have to explain to those coming to Brazil, the athletes, that there is zero risk if you are not a pregnant woman,' said Jaques Wagner, the president's chief of staff. While many in the media and biotech or pharmaceutical industries continue to link Zika virus to microcephaly without any evidence, other health experts have chosen to examine alternative causes behind rising number of birth defects in the region. One of the most likely culprits is pyriproxyfen, a growth-inhibiting larvacide produced by a Monsanto subsidiary which the Brazilian government has been adding to water supplies in impoverished areas for the last one and a half years. Click here to read the related article by Mike Adams and learn about the more likely cause behind this rising health epidemic. 