Chapter 1 Where Did It Come From?
World Health Organization Timeline.
Gaps in the WHO Time Line. According to the WHO “Prior to this (2007), no outbreaks and only 14 cases of human Zika virus disease had been documented anywhere in the world.
The virus has circulated in Southeast Asia for at least the past 50 years,” It was found in Borneo in 1951, in India in 1954, and in Egypt in 1953 (see graph)
Although it is thought that enzootic ZIKV is maintained primarily in a monkey/mosquito transmission cycle, antibodies have been detected in numerous other animal species including water buffalo, elephants, goats, hippos, impala, kongoni, lions, sheep, rodents, wildebeest, and zebras”
Chapter 2 What Is It?
Chapter 3 How Can I Get It?
Chapter 4 Have I Already Had It?
Eighty percent of those infected with Zika never get any symptoms. The World Health Organization puts the number much lower, but they still estimate at least a quarter of people who come down with Zika show no symptoms
Testing is currently only being done in major public health centers and the best results seem to be in the first three days after an active infection.
Chapter 5 How Is It Spread?
(Map from http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0002636 by Feye, et al.
Studies on transmission of Dengue, which is so close to Zika in can lead to false positive lab tests, shows about fifteen percent of baby mosquitoes can transmit Dengue.
In the current epidemic, researchers have found that the mosquitoes aren’t very good at passing on the virus.
Chapter 6 Mosquitoes, Sex, and Blood
The Zika virus officially became a sexually transmitted disease in the U.S. in 2008 when the CDC documented a health care worker infecting his wife with Zika virus far from any infectious mosquitoes.
West Nile virus has been transferred via breast milk, blood transfusions, and from mother to unborn child. Also sexually. Chikungunya (chik-ən-ˈgu̇n-yə) virus has been found in infectious levels in the blood supply. Dengue can be passed directly from organ donor to recipient. In 2009 doctors documented that Yellow Fever can transmit directly from mother to child.
Chapter 7 Birth Defects
The best information we have on the last outbreak in French Polynesia puts the risk to the child at around one percent.
Getting infected with a second strain of dengue isn’t good. It makes it more likely for an adult to have severe dengue and for a pregnant mother’s unborn infant to have severe birth defects.
Chapter 8 Guillain-Barré syndrome
French Polynesia reports retrospective data on its Zika outbreak, which coincided with a dengue outbreak. During the outbreak, 42 cases of Guillain–Barré syndrome were diagnosed- a 20-fold increase over previous years. All 42 cases tested positive for Zika and dengue. The investigation concluded that successive dengue and Zika virus infections might be a predisposing factor for developing Guillain–Barré syndrome.
Chapter 9 How Long Does It Last?
Researchers have found West Nile virus in victims up to seven years after the initial infection. These individuals had the serious nerve involvement of West Nile, and also continued to have symptoms of the infection.
We report the isolation of infectious Zika virus (ZIKV) in cell culture from the saliva of a patient who developed a febrile illness after returning from the Dominican Republic to Italy, in January 2016. The patient had prolonged shedding of viral RNA in saliva and urine
But other species like goats, sheep, and rodents also had antibodies to the Zika virus.
Chapter 10 Can We Avoid Serious Side Effects?
the neutralizing antibody titer against a flavivirus to which the person previously was exposed might be higher than the titer against the virus with which they were most recently infected (20). For example, a person who was previously infected with dengue virus or who received yellow fever vaccine might respond with high levels of neutralizing antibodies against those viruses when later infected with Zika or West Nile viruses.
the development of a dengue virus (DENV) vaccine has been hampered by the requirement of simultaneous protection against four distinct serotypes and the threat that DENV-specific antibodies might either mediate neutralization or, on the contrary, exacerbate disease through the phenomenon of antibody-dependent enhancement (ADE) of infection.
The same drugs that prevent autoimmune disease may lessen the effects of GBS and lower the risk of long-term nerve effects. Treating GBS the way we would any allergic reaction might go a long way toward resolving this serious version of Zika
Chapter 11 What Is The Future of Zika Virus?
Before 1970, only 9 countries had experienced severe dengue epidemics. The disease is now endemic in more than 100 countries in the WHO regions of Africa, the Americas, the Eastern Mediterranean, South-East Asia and the Western Pacific.
But when researchers check blood samples, again about five percent of the population is immune to Zika virus.
The case presentations reported above are paradigmatic of the capacity of long-distance spread of vector-borne infections, such as DENV and CHIKV infection. The unprecedented frequency and the large size of outbreaks which occurred in previously disease-free areas of the world, with no contiguity with known affected areas, are impressive and needs to be investigated in depth.
Increased human mobility is a key factor for the long-distance spread of infectious diseases.
The behaviors that prevent Zika transmission are also those that prevent other sexually transmitted diseases, including Ebola (Disturbingly, the researchers also found examples of transmission from individuals who appeared to be free of the virus after having passed the quarantine period without showing symptoms.)
Mayaro virus, which looks a lot like dengue, has been on the move in areas near the Amazon rainforest. Wesselsbron virus, which infects sheep and mosquitoes, has also been confirmed in humans in South Africa.
There are 219 virus species that are known to be able to infect humans. The first of these to be discovered was yellow fever virus in 1901, and three to four new species are still being found every year.