115-450: Zika fever , also known as Zika virus disease or simply Zika , is an infectious disease caused by the Zika virus . Most cases have no symptoms, but when present they are usually mild and can resemble dengue fever . Symptoms may include fever , red eyes , joint pain , headache, and a maculopapular rash . Symptoms generally last less than seven days. It has not caused any reported deaths during
230-401: A maculopapular rash . Symptoms generally last less than seven days. It has not caused any reported deaths during the initial infection. Infection during pregnancy causes microcephaly and other brain malformations in some babies. Infection in adults has been linked to Guillain–Barré syndrome (GBS) and Zika virus has been shown to infect human Schwann cells . Diagnosis is by testing
345-546: A blood-donor screening study during the French Polynesian Zika outbreak, in which 2.8% (42) of donors from November 2013 and February 2014 tested positive for Zika RNA and were all asymptomatic at the time of blood donation. Eleven of the positive donors reported symptoms of Zika fever after their donation, but only three of 34 samples grew in culture. Zika virus replicates in the mosquito's midgut epithelial cells and then its salivary gland cells. After 5–10 days,
460-543: A greater degree by changes in precipitation and temperature than dengue, making it more likely to be confined to tropical areas. However, rising global temperatures would allow for the disease vector to expand its range further north, allowing Zika to follow. Zika can be transmitted from men and women to their sexual partners; most known cases involve transmission from symptomatic men to women. As of April 2016, sexual transmission of Zika has been documented in six countries – Argentina, Australia, France, Italy, New Zealand, and
575-575: A human disease and spread in a mosquito–human–mosquito cycle, like the yellow fever virus and the dengue fever virus (both flaviviruses), and the chikungunya virus (a togavirus ). Though the reason for the pandemic is unknown, dengue, a related arbovirus that infects the same species of mosquito vectors , is known in particular to be intensified by urbanization and globalization . Zika is primarily spread by Aedes aegypti mosquitoes, and can also be transmitted through sexual contact or blood transfusions . The basic reproduction number ( R 0 ,
690-583: A measure of transmissibility) of Zika virus has been estimated to be between 1.4 and 6.6 . In 2015, news reports drew attention to the rapid spread of Zika in Latin America and the Caribbean. At that time, the Pan American Health Organization published a list of countries and territories that experienced "local Zika virus transmission" comprising Barbados, Bolivia, Brazil, Colombia,
805-536: A narrow equatorial belt from Africa to Asia. From 2007 to 2016 , the virus spread eastward, across the Pacific Ocean to the Americas, leading to the 2015–2016 Zika virus epidemic . The infection, known as Zika fever or Zika virus disease, often causes no or only mild symptoms, similar to a very mild form of dengue fever . While there is no specific treatment, paracetamol (acetaminophen) and rest may help with
920-415: A pace of urbanization which exceeded eradication efforts led to this mosquito's comeback. There is currently no specific treatment for Zika virus infection. Care is supportive with treatment of pain, fever, and itching. Some authorities have recommended against using aspirin and other NSAIDs as these have been associated with hemorrhagic syndrome when used for other flaviviruses. Additionally, aspirin use
1035-552: A pathway which regulates growth of new neurons. In fruit flies, both NS4A and the neighboring NS4B restrict eye growth. Zika fever (also known as Zika virus disease) is an illness caused by Zika virus . Around 80% of cases are estimated to be asymptomatic, though the accuracy of this figure is hindered by the wide variance in data quality, and figures from different outbreaks can vary significantly. Symptomatic cases are usually mild and can resemble dengue fever . Symptoms may include fever , red eyes , joint pain , headache, and
1150-569: A pregnant woman who has Zika fever may die or be born with congenital central nervous system malformations, like microcephaly . In April 1947, as part of studies sponsored by the Rockefeller Foundation into yellow fever , 6 caged rhesus monkeys were placed in the canopy of the Zika Forest of Uganda. On April 18 one of the monkeys (no. 776) developed a fever and blood samples revealed the first known case of Zika fever. Population surveys at
1265-537: A pregnant women living in Kerala state. A 1954 study assessing blood samples from several people from different states found antibodies to Zika in healthy people in India which could indicate past exposure, though it could also be due to cross-reaction with other flaviviruses. By using phylogenetic analysis of Asian strains, it was estimated that Zika virus had moved to Southeast Asia by 1945. In 1977–1978, Zika virus infection
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#17328518670781380-453: A similar manner. The main routes of transmission of vertically transmitted infections are across the placenta (transplacental) and across the female reproductive tract during childbirth. Transmission is also possible by breaks in the maternal-fetal barrier such by amniocentesis or major trauma . The embryo and fetus have little or no immune function . They depend on the immune function of their mother. Several pathogens can cross
1495-612: A thorough physical investigation for neurologic abnormalities, dysmorphic features, splenomegaly, hepatomegaly, and rash or other skin lesions. Other recommended tests are cranial ultrasound, hearing evaluation, and eye examination. Testing should be done for any abnormalities encountered as well as for other congenital infections such as syphilis , toxoplasmosis , rubella, cytomegalovirus infection, lymphocytic choriomeningitis virus infection, and herpes simplex virus . Some tests should be repeated up to 6 months later as there can be delayed effects, particularly with hearing. In response to
1610-506: A vaccine is unlikely to be widely available for about 10 years. In June 2016, the FDA granted the first approval for a human clinical trial for a Zika vaccine. In March 2017, a DNA vaccine was approved for phase-2 clinical trials. This vaccine consists of a small, circular piece of DNA, known as a plasmid, that expresses the genes for the Zika virus envelope proteins. As the vaccine does not contain
1725-435: A vertically transmitted infection. The hepatitis B virus is large and does not cross the placenta. Hence, it cannot infect the fetus unless breaks in the maternal-fetal barrier have occurred, but such breaks can occur in bleeding during childbirth or amniocentesis . The TORCH complex was originally considered to consist of the four conditions mentioned above, with the "TO" referring to Toxoplasma . The four-term form
1840-454: A very large surge of reports of infants born with microcephaly , with 20 times the number of expected cases. Many of these cases have since been confirmed, leading WHO officials to project that approximately 2,500 infants will be found to have born in Brazil with Zika-related microcephaly. Zika virus Zika virus ( ZIKV ; pronounced / ˈ z iː k ə / or / ˈ z ɪ k ə / )
1955-400: A week and is usually mild enough that people do not have to go to a hospital. Due to being in the same family as dengue, there has been concern that it could cause similar bleeding disorders. However that has only been documented in one case, with blood seen in semen, also known as hematospermia . Zika virus infections have been strongly associated with Guillain–Barré syndrome (GBS), which
2070-532: A whole host of novel technologies are under current development for mosquito control and the World Health Organization has recently lent its support for the accelerated development of modern methods for mosquito control such as the use of Wolbachia bacteria to render mosquitoes resistant to the virus, and, the release of sterilized male mosquitoes that breed with wild female mosquitoes to give rise to non-viable offspring (offspring that do not survive to
2185-541: Is a mosquito - borne flavivirus closely related to the dengue and yellow fever viruses. While mosquitoes are the vector , the main reservoir species remains unknown, though serological evidence has been found in both West African monkeys and rodents. Transmission is via the bite of mosquitoes from the genus Aedes , primarily Aedes aegypti in tropical regions. It has also been isolated from Ae. africanus , Ae. apicoargenteus , Ae. luteocephalus , Ae. albopictus , Ae. vittatus and Ae. furcifer . During
2300-474: Is a member of the virus family Flaviviridae . It is spread by daytime-active Aedes mosquitoes, such as A. aegypti and A. albopictus . Its name comes from the Ziika Forest of Uganda , where the virus was first isolated in 1947. Zika virus shares a genus with the dengue , yellow fever , Japanese encephalitis , and West Nile viruses. Since the 1950s, it has been known to occur within
2415-434: Is a rapid onset of muscle weakness caused by the immune system damaging the peripheral nervous system, and which can progress to paralysis. While both GBS and Zika infection can simultaneously occur in the same individual, it is difficult to definitively identify Zika virus as the cause of GBS. Though Zika virus has been shown to infect human Schwann cells . Several countries affected by Zika outbreaks have reported increases in
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#17328518670782530-415: Is an infection caused by pathogenic bacteria or viruses that use mother-to-child transmission , that is, transmission directly from the mother to an embryo , fetus , or baby during pregnancy or childbirth . It can occur when the mother has a pre-existing disease or becomes infected during pregnancy. Nutritional deficiencies may exacerbate the risks of perinatal infections. Vertical transmission
2645-609: Is detected in 3% of asymptomatic blood donors in French Polynesia. In fruit flies microcephaly appears to be caused by the flavivirid virus protein NS4A , which can disrupt brain growth by hijacking a pathway which regulates growth of new neurons. It is difficult to diagnose Zika virus infection based on clinical signs and symptoms alone due to overlaps with other arboviruses that are endemic to similar areas. The US Centers for Disease Control and Prevention (CDC) advises that "based on
2760-586: Is expanding due to global trade and travel. A. aegypti distribution is now the most extensive ever recorded – on parts of all continents except Antarctica, including North America and even the European periphery ( Madeira , the Netherlands, and the northeastern Black Sea coast). A mosquito population capable of carrying Zika has been found in a Capitol Hill neighborhood of Washington, DC, and genetic evidence suggests they survived at least four consecutive winters in
2875-528: Is generally avoided in children when possible due to the risk of Reye syndrome . Zika virus had been relatively little studied until the major outbreak in 2015, and no specific antiviral treatments are available as yet. Advice to pregnant women is to avoid any risk of infection so far as possible, as once infected there is little that can be done beyond supportive treatment. Most of the time, Zika fever resolves on its own in two to seven days, but rarely, some people develop Guillain–Barré syndrome . The fetus of
2990-463: Is important for the mathematical modelling of infectious diseases , especially for diseases of animals with large litter sizes, as it causes a wave of new infectious individuals. Bacteria, viruses, and other organisms are able to be passed from mother to child. Several vertically transmitted infections are included in the TORCH complex : Other infections include: Hepatitis B may also be classified as
3105-522: Is no effective vaccine . Health officials recommended that women in areas affected by the 2015–16 Zika outbreak consider putting off pregnancy and that pregnant women not travel to these areas. While there is no specific treatment, paracetamol (acetaminophen) may help with the symptoms. Admission to hospital is rarely necessary. The virus that causes the disease was first isolated in Africa in 1947. The first documented outbreak among people occurred in 2007 in
3220-547: Is not known, but they appear to be common, with large scale abnormalities seen in up to 42% of live births. The most common observed associations have been abnormalities with brain and eye development such as microcephaly and chorioretinal scarring. Less commonly there have been systemic abnormalities such as hydrops fetalis , where there is abnormal accumulation of fluid in the fetus. These abnormalities can lead to intellectual problems, seizures , vision problems , hearing problems , problems feeding and slow development. Whether
3335-456: Is primarily during or after birth, medical intervention can help prevent infections in the infant. During birth, babies are exposed to maternal blood , body fluids , and to the maternal genital tract without the placental barrier intervening. Because of this, blood-borne microorganisms (hepatitis B, HIV), organisms associated with sexually transmitted infections (e.g., Neisseria gonorrhoeae and Chlamydia trachomatis ), and normal fauna of
3450-406: Is still used in many modern references, and the capitalization "ToRCH" is sometimes used in these contexts. The acronym has also been listed as TORCHES, for TOxoplasmosis, Rubella, Cytomegalovirus, HErpes simplex, and Syphilis. A further expansion of this acronym, CHEAPTORCHES, was proposed by Ford-Jones and Kellner in 1995: The signs and symptoms of a vertically transmitted infection depend on
3565-550: Is unclear why levels in semen can be higher than other body fluids, and it is also unclear how long infectious virus can remain in semen. There have also been cases of men with no symptoms of Zika virus infection transmitting the disease. The CDC has recommended that all men who have travelled to affected areas should wait at least 6 months before trying to attempt conception , regardless of whether they were ill. To date there have been no reported sexual transmissions from women to their sexual partners. Oral, anal or vaginal sex can spread
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3680-578: Is used to kill flying mosquitoes and larvicide can be used in water containers. Because Zika virus can be sexually transmitted, men who have gone to an area where Zika fever is occurring should be counseled to either abstain from sex or use condoms for 6 months after travel if their partner is pregnant or could potentially become pregnant. Breastfeeding is still recommended by the WHO, even by women who have had Zika fever. There have been no recorded cases of Zika transmission to infants through breastfeeding, though
3795-773: The Cook Islands , and New Caledonia . There was an epidemic in 2015 and 2016 in the Americas . The outbreak began in April ;2015 in Brazil , and spread to other countries in South America , Central America , North America , and the Caribbean . In January 2016, the WHO said the virus was likely to spread throughout most of the Americas by the end of the year; and in February 2016,
3910-740: The Cook Islands . The source of the virus was thought to be an independent introduction of the virus from Southeast Asia , unrelated to the Yap Islands outbreak. Genetic analyses of Zika virus strains suggest that Zika first entered the Americas between May and December 2013. It was first detected in the Western Hemisphere in February 2014, and rapidly spread throughout South and Central America, reaching Mexico in November 2015. In 2016 it established local transmission in Florida and Texas. The first death in
4025-603: The FDA has authorized two tests to detect Zika virus antibodies. The CDC recommends screening some pregnant women even if they do not have symptoms of infection. Pregnant women who have traveled to affected areas should be tested between two and twelve weeks after their return from travel. Due to the difficulties with ordering and interpreting tests for Zika virus, the CDC also recommends that healthcare providers contact their local health department for assistance. For women living in affected areas,
4140-620: The Federated States of Micronesia . An outbreak started in Brazil in 2015, and spread to the Americas, Pacific, Asia, and Africa. This led the World Health Organization to declare it a Public Health Emergency of International Concern in February 2016. The emergency was lifted in November 2016, but 84 countries still reported cases as of March 2017. The last proven case of Zika spread in the Continental United States
4255-611: The Robert Koch-Institut reported 29 imported Zikavirus cases imported into Germany. Of the altogether 16 imported Zika virus cases in 2023, 10 were diagnosed after a trip to Thailand with 62% of all Zika virus cases a significant relative and absolute increase. [REDACTED] This article incorporates public domain material from websites or documents of the Centers for Disease Control and Prevention . Vertically transmitted infection A vertically transmitted infection
4370-530: The genitourinary tract (e.g., Candida albicans ) are among those commonly seen in infection of newborns. In the spectrum of optimal virulence , vertical transmission tends to evolve benign symbiosis , so is a critical concept for evolutionary medicine . Because a pathogen's ability to pass from mother to child depends significantly on the hosts' ability to reproduce, pathogens' transmissibility tends to be inversely related to their virulence. In other words, as pathogens become more harmful to, and thus decrease
4485-424: The placenta and cause perinatal infection. Often, microorganisms that produce minor illness in the mother are very dangerous for the developing embryo or fetus. This can result in spontaneous abortion or major developmental disorders . For many infections, the baby is more at risk at particular stages of pregnancy. Problems related to perinatal infection are not always directly noticeable. Apart from infecting
4600-569: The replicative virus has been detected in breast milk. When returning from travel, with or without symptoms, it is suggested that prevention of mosquito bites continue for 3 weeks in order reduce the risk of virus transmission to uninfected mosquitos. Because of the "growing evidence of a link between Zika and microcephaly", in January 2016, the CDC issued a travel alert advising pregnant women to consider postponing travel to countries and territories with ongoing local transmission of Zika virus. Later,
4715-452: The 12-kDa capsid protein. The nucleocapsid, in turn, is enveloped within a host-derived membrane modified with two viral glycoproteins . Viral genome replication depends on the making of double-stranded RNA from the single-stranded, positive-sense RNA (ssRNA(+)) genome followed by transcription and replication to provide viral mRNAs and new ssRNA(+) genomes. A longitudinal study shows that 6 hours after cells are infected with Zika virus ,
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4830-475: The 2007 outbreak on Yap Island in the South Pacific, Aedes hensilli was the vector, while Aedes polynesiensis spread the virus in French Polynesia in 2013. Zika virus can also spread by sexual transmission from infected men to their partners. Zika virus has been isolated from semen samples, with one person having 100,000 times more virus in semen than blood or urine, two weeks after being infected. It
4945-434: The 2013–2014 outbreak . The Asian strain appears to have first evolved around 1928. The vertebrate hosts of the virus were primarily monkeys in a so-called enzootic mosquito-monkey-mosquito cycle, with only occasional transmission to humans. Before 2007, Zika "rarely caused recognized 'spillover' infections in humans, even in highly enzootic areas". Infrequently, however, other arboviruses have become established as
5060-484: The Americas the number of cases peaked during the first half of 2016 and declined through 2017–2018, with a total of 31,587 suspected, probable, and confirmed cases of ZIKV disease were reported in the Region of the Americas. Of these, 3,473 (11%) were laboratory confirmed. In general, transmission persists at low levels in some areas and is not uniformly distributed within countries. In 2016 imported or locally transmitted Zika
5175-405: The CDC has advised men who have traveled to an area with Zika should use condoms or not have sex for at least six months after their return as the virus is still transmissible even if symptoms never develop. Zika virus can spread by vertical (or "mother-to-child") transmission , during pregnancy or at delivery. An infection during pregnancy has been linked to changes in neuronal development of
5290-519: The CDC has recommended testing at the first prenatal visit with a doctor as well as in the mid-second trimester , though this may be adjusted based on local resources and the local burden of Zika virus. Additional testing should be done if there are any signs of Zika virus disease. Women with positive test results for Zika virus infection should have their fetus monitored by ultrasound every three to four weeks to monitor fetal anatomy and growth. For infants with suspected congenital Zika virus disease,
5405-404: The CDC recommends testing with both serologic and molecular assays such as RT-PCR, IgM ELISA and plaque reduction neutralization test (PRNT). RT-PCR of the infants serum and urine should be performed in the first two days of life. Newborns with a mother who was potentially exposed and who have positive blood tests, microcephaly or intracranial calcifications should have further testing including
5520-415: The CDC travel advisories included: In December 2020, no active Zika outbreaks were reported by the CDC. Both the regional Pan American Health Organization (PAHO) as well as the WHO have issued statements of concern about the widespread public health impact of the Zika virus and its links to GBS and microcephaly. The WHO Director-General, Margaret Chan , issued a statement in February 2016 "declaring that
5635-466: The Dominican Republic, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Puerto Rico, Saint Martin, Suriname, and Venezuela. By August 2016, more than 50 countries had experienced active (local) transmission of Zika virus . Zika is primarily spread by the female Aedes aegypti mosquito, which is active mostly in
5750-864: The Indian Air Force in Kanpur tested positive for Zika virus, making it the first reported case in the Indian state of Uttar Pradesh . On 22 March 2016, Reuters reported that Zika was isolated from a 2014 blood sample of an elderly man in Chittagong in Bangladesh as part of a retrospective study . Between August and November 2016, 455 cases of Zika virus infection were confirmed in Singapore . In 2023, 722 Zika virus cases were reported in Thailand. From 2019-2022
5865-643: The United States due to Zika occurred in February 2016. In May 2015, Brazil officially reported its first 16 cases of the illness. Although, a case of illness was reported in March 2015 in a returning traveller. According to the Brazilian Health Ministry, as of November 2015 there was no official count of the number of people infected with the virus in Brazil, since the disease is not subject to compulsory notification. Even so, cases were reported in 14 states of
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#17328518670785980-539: The United States has declined as a result of the implementation of recommendations on HIV counselling and voluntary testing practices and the use of zidovudine therapy by providers to reduce perinatal HIV transmission. The price paid in the evolution of symbiosis is, however, great: for many generations, almost all cases of vertical transmission continue to be pathological—in particular if any other routes of transmission exist. Many generations of random mutation and selection are needed to evolve symbiosis. During this time,
6095-449: The United States – during the 2015 outbreak. ZIKV can persist in semen for several months, with viral RNA detected up to one year. The virus replicates in the human testis, where it infects several cell types including testicular macrophages, peritubular cells and germ cells, the spermatozoa precursors. Semen parameters can be altered in patients for several weeks post-symptoms onset, and spermatozoa can be infectious. Since October 2016,
6210-465: The WHO declared the cluster of microcephaly and Guillain–Barré syndrome cases reported in Brazil – strongly suspected to be associated with the Zika outbreak – a Public Health Emergency of International Concern . It was estimated that 1.5 million people were infected by Zika in Brazil, with over 3,500 cases of microcephaly reported between October 2015 and January 2016. A number of countries issued travel warnings , and
6325-476: The WHO warned that the virus is likely to spread to nearly all countries of the Americas, since its vector, the mosquito Aedes aegypti , is found in all countries in the region, except for Canada and continental Chile . The mosquito and dengue fever have been detected in Chile's Easter Island, some 3,500 km (2,200 mi) away from its closest point in mainland Chile, since 2002. In February 2016, WHO declared
6440-598: The ZIKV IgM antibodies. In 2017, Angola reported two cases of Zika fever. Zika was also occurring in Tanzania as of 2016. In April 2007, the first outbreak outside of Africa and Asia occurred on the island of Yap in the Federated States of Micronesia, characterized by rash, conjunctivitis, and arthralgia, which was initially thought to be dengue, chikungunya , or Ross River disease . Serum samples from patients in
6555-412: The Zika outbreak, only an average of 150 to 200 cases per year were reported in Brazil. In the state of Pernambuco the reported rates of microcephaly in 2015 are 77 times higher than in the previous 5 years. A model using data from a Zika outbreak in French Polynesia estimated the risk of microcephaly in children born to mothers who acquired Zika virus in the first trimester to be 1%. On 24 January 2016,
6670-531: The acute phase of illness contained RNA of Zika. There were 49 confirmed cases, 59 unconfirmed cases, no hospitalizations, and no deaths. After October 2013 Oceania's first outbreak showed an estimated 11% population infected for French Polynesia that also presented with Guillain–Barre syndrome (GBS). The spread of ZIKV continued to New Caledonia, Easter Island, and the Cook Islands and where 1385 cases were confirmed by January 2014. During
6785-472: The advice was updated to caution pregnant women to avoid these areas entirely if possible and, if travel is unavoidable, to protect themselves from mosquito bites. Male partners of pregnant women and couples contemplating pregnancy who must travel to areas where Zika is active are advised to use condoms or abstain from sex. The agency also suggested that women thinking about becoming pregnant should consult with their physicians before traveling. In September 2016,
6900-415: The affected countries currently centres around mosquito control. Several approaches are available for the management of Aedes aegypti mosquito populations, including the destruction of larval breeding sites (the aquatic pools in which eggs are laid and larvae hatch prior to mosquito development into flying adults); and, insecticides targeting either the larval stages, adult mosquitoes or both. Additionally,
7015-525: The anemia and parasitemia of the pregnant women, and birthweight in their infants. If the mother has active herpes simplex (as may be suggested by a pap test ), delivery by Caesarean section can prevent the newborn from contact, and consequent infection, with this virus. IgG 2 antibody may play a crucial role in prevention of intrauterine infections and extensive research is going on for developing IgG 2 -based therapies for treatment and vaccination. Each type of vertically transmitted infection has
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#17328518670787130-498: The baby. Diagnosis is by testing the blood, urine, or saliva for the presence of the virus's RNA when the person is sick, or the blood for antibodies after symptoms are present more than a week. Prevention involves decreasing mosquito bites in areas where the disease occurs and proper use of condoms. Efforts to prevent bites include the use of insect repellent , covering much of the body with clothing, mosquito nets , and getting rid of standing water where mosquitoes reproduce. There
7245-682: The biting, adult stage). Oxitec 's genetically modified OX513A mosquito was approved by Brazil's National Biosecurity Technical Commission (CTNBio) in April 2014 and it was being used to try to combat mosquitoes carrying the Zika virus in the town of Piracicaba , São Paulo in 2016. In the 1940s and 1950s, the Aedes aegypti mosquito was eradicated on some Caribbean islands and in at least eighteen Latin American countries. Decreasing political will and presumably available money, mosquito resistance to insecticide, and
7360-467: The blood, urine, or saliva for the presence of Zika virus RNA when the person is sick. In 2019, an improved diagnostic test, based on research from Washington University in St. Louis , that detects Zika infection in serum was granted market authorization by the FDA . Prevention involves decreasing mosquito bites in areas where the disease occurs, and proper use of condoms. Efforts to prevent bites include
7475-564: The cell has been infected, the virus restructures the endoplasmic reticulum, forming the large vacuoles, resulting in cell death. There are two Zika lineages: the African lineage and the Asian lineage. Phylogenetic studies indicate that the virus spreading in the Americas is 89% identical to African genotypes, but is most closely related to the Asian strain that circulated in French Polynesia during
7590-407: The country and become the primary vector for the concomitant chikungunya and dengue virus outbreaks. New outbreaks can occur if a person carrying the virus travels to another region where A. albopictus is common. The potential societal risk of Zika can be delimited by the distribution of the mosquito species that transmit it. The global distribution of the most cited carrier of Zika, A. aegypti ,
7705-509: The country. Mosquito-borne Zika virus is suspected to be the cause of 2,400 possible cases of microcephaly and 29 infant deaths in Brazil in 2015 (of the 2400 or so notified cases in 2015, 2165 were under investigation in December 2015, 134 were confirmed and 102 were ruled out for microcephaly). The Brazilian Health Ministry has reported at least 2,400 suspected cases of microcephaly in the country in 2015 as of 12 December, and 29 fatalities. Before
7820-613: The daytime. The mosquitos must feed on blood to lay eggs. The virus has also been isolated from a number of arboreal mosquito species in the genus Aedes , such as A. africanus , A. apicoargenteus , A. furcifer , A. hensilli , A. luteocephalus , and A. vittatus , with an extrinsic incubation period in mosquitoes around 10 days. The true extent of the vectors is still unknown. Zika has been detected in many more species of Aedes , along with Anopheles coustani, Mansonia uniformis , and Culex perfuscus , although this alone does not incriminate them as vectors. To detect
7935-604: The disease. Cases of vertical perinatal transmission have been reported. The CDC recommends that women with Zika fever should wait at least 8 weeks after they start having symptoms of disease before attempting to conceive. There have been no reported cases of transmission from breastfeeding, but infectious virus has been found in breast milk. Like other flaviviruses it could potentially be transmitted by blood transfusion and several affected countries have developed strategies to screen blood donors. The U.S. FDA has recommended universal screening of blood products for Zika. The virus
8050-647: The epidemic in the Americas. It is named after the Zika Forest near Entebbe , Uganda , where the Zika virus was first identified. Zika virus was first identified in the late 1940s in Kampala, Uganda, Africa but was first confirmed in Brazil. Since it was first identified, Zika has been found in more than 27 countries and territories. Following the initial Zika outbreak in Northeastern Brazil in May 2015, physicians observed
8165-428: The fetus, transplacental pathogens may cause placentitis (inflammation of the placenta) and/or chorioamnionitis (inflammation of the fetal membranes ). Babies can also become infected by their mothers during birth . Some infectious agents may be transmitted to the embryo or fetus in the uterus, while passing through the birth canal, or even shortly after birth. The distinction is important because when transmission
8280-499: The full sequence of the virus, it cannot cause infection. As of April 2017, both subunit and inactivated vaccines have entered clinical trials. The virus was first isolated in April 1947 from a rhesus macaque monkey placed in a cage in the Ziika Forest of Uganda , near Lake Victoria , by the scientists of the Yellow Fever Research Institute . A second isolation from the mosquito A. africanus followed at
8395-631: The genus Flavivirus , thus is related to the dengue , yellow fever , Japanese encephalitis , and West Nile viruses. Like other flaviviruses, Zika virus is enveloped and icosahedral and has a nonsegmented, single-stranded, 10 kilobase , positive-sense RNA genome . It is most closely related to the Spondweni virus and is one of the two known viruses in the Spondweni virus clade . A positive-sense RNA genome can be directly translated into viral proteins. As in other flaviviruses, such as
8510-455: The individual pathogen. In the mother, it may cause subtle signs such as an influenza-like illness , or possibly no symptoms at all. In such cases, the effects may be seen first at birth. Symptoms of a vertically transmitted infection may include fever and flu-like symptoms. The newborn is often small for gestational age . A petechial rash on the skin may be present, with small reddish or purplish spots due to bleeding from capillaries under
8625-543: The infant, and considering that Zika virus infection among infants is mild, the balance between desirable and undesirable effects favours breastfeeding versus not breastfeeding. According to the 2021WHO guidelines: The virus is spread by mosquitoes, making mosquito avoidance an important element to disease control. The CDC recommends that individuals: The CDC also recommends strategies for controlling mosquitoes such as eliminating standing water, repairing septic tanks and using screens on doors and windows. Spraying insecticide
8740-426: The initial infection. Mother-to-child transmission during pregnancy can cause microcephaly and other brain malformations in some babies. Infections in adults have been linked to Guillain–Barré syndrome (GBS). Zika fever is mainly spread via the bite of mosquitoes of the Aedes type. It can also be sexually transmitted and potentially spread by blood transfusions . Infections in pregnant women can spread to
8855-637: The main vector of transmission. While the way of introduction of the virus on Yap Island remains uncertain, it is likely to have happened through introduction of infected mosquitoes or a human infected with a strain related to those in Southeast Asia. This was also the first time Zika fever had been reported outside Africa and Asia. Before the Yap Island outbreak, only 14 human cases had ever been reported. In 2013–2014, several outbreaks of Zika were reported in French Polynesia , New Caledonia , Easter Island and
8970-485: The microcephaly phenotype and/or enhance damage during pregnancy, but it is unknown whether this occurs in humans. As of April 2016 , two cases of Zika transmission through blood transfusions have been reported globally, both from Brazil, after which the US Food and Drug Administration (FDA) recommended screening blood donors and deferring high-risk donors for 4 weeks. A potential risk had been suspected based on
9085-800: The number of new Zika virus cases in the Americas had fallen dramatically. On May 15, 2017, three cases of Zika virus infection in India were reported in the state of Gujarat . By late 2018, there had been at least 159 cases in Rajasthan and 127 in Madhya Pradesh . In July 2021, the first case of Zika virus infection in the Indian state of Kerala was reported. After the first confirmed case, 19 other people who had previously presented symptoms were tested, and 13 of those had positive results, showing that Zika had been circulating in Kerala since at least May 2021. By August 6th 2021, there had been 65 reported cases in Kerala. On October 22, 2021, an officer in
9200-483: The outbreak a Public Health Emergency of International Concern as evidence grew that Zika is a cause of birth defects and neurological problems. In April 2016, WHO stated there is a scientific consensus, based on preliminary evidence, that Zika is a cause of microcephaly in infants and Guillain–Barré syndrome in adults. Studies of this and prior outbreaks have found Zika infection during pregnancy to be associated with early pregnancy loss and other pregnancy problems. In
9315-507: The outbreak was expected to significantly impact the tourism industry. Several countries took the unusual step of advising their citizens to delay pregnancy until more was known about the virus and its impact on fetal development. With the 2016 Summer Olympics hosted in Rio de Janeiro , health officials worldwide voiced concerns over a potential crisis, both in Brazil and when international athletes and tourists returned home and possibly would spread
9430-465: The patient affected is already taking treatment for another medical condition it is advisable to inform your attending physician before taking any other drug or additional treatment; The World Health Organization has suggested that priority should be to develop inactivated vaccines and other nonlive vaccines, which are safe to use in pregnant women. As of March 2016 , 18 companies and institutions were developing vaccines against Zika, but they state
9545-411: The period of viremia can be short and the World Health Organization (WHO) recommends RT-PCR testing be done on serum collected within 1 to 3 days of symptom onset or on saliva samples collected during the first 3 to 5 days. When evaluating paired samples, Zika virus was detected more frequently in saliva than serum. Urine samples can be collected and tested up to 14 days after the onset of symptoms, as
9660-489: The presence of the virus usually requires genetic material to be analysed in a lab using the technique RT-PCR . A much cheaper and faster method involves shining a light at the head and thorax of the mosquito, and detecting chemical compounds characteristic of the virus using near-infrared spectroscopy . Transmission by A. albopictus , the tiger mosquito, was reported from a 2007 urban outbreak in Gabon, where it had newly invaded
9775-402: The rate of new cases of GBS. During the 2013–2014 outbreak in French Polynesia there were 42 reported cases of GBS over a 3-month period, compared to between 3 and 10 annually prior to the outbreak. The disease spreads from mother to child in the womb and can cause multiple problems, most notably microcephaly , in the baby. The full range of birth defects caused by infection during pregnancy
9890-495: The recent cluster of microcephaly cases and other neurological disorders reported in Brazil, following a similar cluster in French Polynesia in 2014, constitutes a Public Health Emergency of International Concern." The declaration allowed the WHO to coordinate international response to the virus as well as gave its guidance the force of international law under the International Health Regulations . The declaration
10005-409: The region. The study authors conclude that mosquitos are adapting for persistence in a northern climate. Zika virus appears to be contagious via mosquitoes for around a week after infection. The virus is thought to be infectious for a longer period of time after infection (at least 2 weeks) when transmitted via semen . Research into its ecological niche suggests that Zika may be influenced to
10120-439: The reproduction rate of, their host organism, they are less likely to be passed on to the hosts' offspring since they will have fewer offspring. Although HIV is sometimes transmitted through perinatal transmission, its virulence can be accounted for because its primary mode of transmission is not vertical. Moreover, medicine has further decreased the frequency of vertical transmission of HIV. The incidence of perinatal HIV cases in
10235-523: The same site in January 1948. When the monkey developed a fever, researchers isolated from its serum a "filterable transmissible agent" which was named Zika in 1948. Zika was first known to infect humans from the results of a serological survey in Uganda, published in 1952. Of 99 human blood samples tested, 6.1% had neutralizing antibodies. As part of a 1954 outbreak investigation of jaundice suspected to be yellow fever, researchers reported isolation of
10350-517: The same year, Easter Island acknowledged 51 cases. Australia began seeing cases in 2012. Research showed it was brought by travelers returning from Indonesia and other infected countries. New Zealand also experienced infections rate increases through returning foreign travelers. Oceania countries experiencing Zika today are New Caledonia, Vanuatu, Solomon Islands, Marshall Islands, American Samoa, Samoa, and Tonga. Between 2013 and 2014, further epidemics occurred in French Polynesia , Easter Island ,
10465-465: The similarly sized West Nile virus, the RNA genome encodes seven nonstructural proteins and three structural proteins in the form of a single polyprotein ( Q32ZE1 ). One of the structural proteins encapsulates the virus. This protein is the flavivirus envelope glycoprotein, that binds to the endosomal membrane of the host cell to initiate endocytosis. The RNA genome forms a nucleocapsid along with copies of
10580-525: The skin. An enlarged liver and spleen ( hepatosplenomegaly ) is common, as is jaundice . However, jaundice is less common in hepatitis B because a newborn's immune system is not developed well enough to mount a response against liver cells, as would normally be the cause of jaundice in an older child or adult. Hearing impairment , eye problems, mental retardation , autism , and death can be caused by vertically transmitted infections. The genetic conditions of Aicardi-Goutieres syndrome are possibly present in
10695-401: The specific pathogens or by increased levels of IgM against the pathogen. A vertically transmitted infection can be called a perinatal infection if it is transmitted in the perinatal period , which starts at gestational ages between 22 and 28 weeks (with regional variations in the definition) and ending seven completed days after birth. The term congenital infection can be used if
10810-531: The stage of pregnancy at which the mother becomes infected affects the risk to the fetus is not well understood, nor is whether other risk factors affect outcomes. One group has estimated the risk of a baby developing microcephaly at about 1% when the mother is infected during the first trimester, with the risk of developing microcephaly becoming uncertain beyond the first trimester. Affected babies might appear normal but actually have brain abnormalities; infection in newborns could also lead to brain damage. Zika virus
10925-486: The symptoms. Admission to a hospital is rarely necessary. It is advised, for an affected person with the zika virus, to drink a lot of water to stay hydrated, to lie down, and to treat the fever and agony with liquid solutions; taking drugs like acetaminophen or paracetamol helps to relieve fever and pain. Referring to the US CDC it is not recommended to take anti-inflammatory and non-steroid drugs like aspirin for example. If
11040-636: The symptoms. As of April 2019, no vaccines have been approved for clinical use, however a number of vaccines are currently in clinical trials. Zika can spread from a pregnant woman to her baby. This can result in microcephaly , severe brain malformations , and other birth defects. Zika infections in adults may result rarely in Guillain–Barré syndrome . In January 2016, the United States Centers for Disease Control and Prevention (CDC) issued travel guidance on affected countries, including
11155-638: The time in Uganda found 6.1% of individuals to be seropositive for Zika. The first human cases were reported in Nigeria in 1954. A few outbreaks have been reported in tropical Africa and in some areas in Southeast Asia. Until recently there were no documented cases of Zika virus in the Indian subcontinent , however, the first cases were reported in 2017 from Gujarat state and Tamil Nadu, more cases were reported in Rajasthan state involving an outbreak of 153 reported cases and in
11270-731: The typical clinical features, the differential diagnosis for Zika virus infection is broad. In addition to dengue, other considerations include leptospirosis , malaria , rickettsia , group A streptococcus , rubella , measles , and parvovirus , enterovirus , adenovirus , and alphavirus infections (e.g., chikungunya, Mayaro , Ross River , Barmah Forest , O'nyong'nyong , and Sindbis viruses)." In small case series, routine chemistry and complete blood counts have been normal in most patients. A few have been reported to have mild leukopenia , thrombocytopenia , and elevated liver transaminases . Zika virus can be identified by reverse transcriptase PCR (RT-PCR) in acutely ill patients. However,
11385-432: The unborn child. Severe progressions of infection have been linked to the development of microcephaly in the unborn child, while mild infections potentially can lead to neurocognitive disorders later in life. Congenital brain abnormalities other than microcephaly have also been reported after a Zika outbreak. Studies in mice have suggested that maternal immunity to dengue virus may enhance fetal infection with Zika, worsen
11500-471: The use of DEET or picaridin - based insect repellent , covering much of the body with clothing, mosquito nets , and getting rid of standing water where mosquitoes reproduce. There is no vaccine . Health officials recommended that women in areas affected by the 2015–2016 Zika outbreak consider putting off pregnancy and that pregnant women not travel to these areas. While no specific treatment exists, paracetamol (acetaminophen) and rest may help with
11615-485: The use of enhanced precautions, and guidelines for pregnant women including considering postponing travel. Other governments or health agencies also issued similar travel warnings, while Colombia , the Dominican Republic , Puerto Rico , Ecuador , El Salvador , and Jamaica advised women to postpone getting pregnant until more is known about the risks. Zika virus belongs to the family Flaviviridae and
11730-408: The vacuoles and mitochondria in the cells begin to swell. This swelling becomes so severe, it results in cell death, also known as paraptosis. This form of programmed cell death requires gene expression. IFITM3 is a trans-membrane protein in a cell that is able to protect it from viral infection by blocking virus attachment. Cells are most susceptible to Zika infection when levels of IFITM3 are low. Once
11845-442: The vast majority of vertical transmission cases exhibit the initial virulence. In dual inheritance theory , vertical transmission refers to the passing of cultural traits from parents to children. When physical examination of the newborn shows signs of a vertically transmitted infection, the examiner may test blood, urine, and spinal fluid for evidence of the infections listed above. Diagnosis can be confirmed by culture of one of
11960-539: The vertically transmitted infection persists after childbirth. Some vertically transmitted infections, such as toxoplasmosis and syphilis, can be effectively treated with antibiotics if the mother is diagnosed early in her pregnancy. Many viral vertically transmitted infections have no effective treatment, but some, notably rubella and varicella-zoster, can be prevented by vaccinating the mother prior to pregnancy. Pregnant women living in malaria-endemic areas are candidates for malaria prophylaxis . It clinically improves
12075-599: The virus can be found in the mosquito's saliva. If the mosquito's saliva is inoculated into human skin, the virus can infect epidermal keratinocytes, skin fibroblasts in the skin and the Langerhans cells . The pathogenesis of the virus is hypothesized to continue with a spread to lymph nodes and the bloodstream. Flaviviruses replicate in the cytoplasm , but Zika antigens have been found in infected cell nuclei. The viral protein numbered NS4A can lead to small head size ( microcephaly ) because it disrupts brain growth by hijacking
12190-411: The virus from a patient, but the pathogen was later shown to be the closely related Spondweni virus . Spondweni was also determined to be the cause of a self-inflicted infection in a researcher reported in 1956. Subsequent serological studies in several African and Asian countries indicated the virus had been widespread within human populations in these regions. The first true case of human infection
12305-532: The virus has been seen to survive longer in the urine than either saliva or serum. The longest period of detectable virus has been 11 days and Zika virus does not appear to establish latency. Later on, serology for the detection of specific IgM and IgG antibodies to Zika virus can be used. IgM antibodies can be detectable within 3 days of the onset of illness. Serological cross-reactions with closely related flaviviruses such as dengue and West Nile virus as well as vaccines to flaviviruses are possible. As of 2019,
12420-410: The virus. Some researchers speculated that only one or two tourists might be infected during the three-week period, or approximately 3.2 infections per 100,000 tourists. In November 2016, the World Health Organization declared that Zika virus was no longer a global emergency while noting that the virus still represents "a highly significant and a long-term problem". As of August 2017
12535-406: The widespread transmission of Zika virus during the 2016 outbreak and concerns of viral genetic material detected in breast milk the World Health Organization (WHO) released a Guideline of infant feeding in areas of Zika virus transmission, first in 2016 and updated in 2021, where the evidence showed that despite the detection of Zika virus in breast milk, there is unclear evidence of transmission to
12650-484: Was described as a cause of fever in Indonesia. Before 2007, there were only 13 reported natural infections with Zika virus, all with a mild, self-limited febrile illness. As of July 2019, evidence of local transmission from mosquitoes to humans has been reported in a total of 87 countries from four of six WHO Regions ; African, Americas, South-East Asia and Western Pacific. The first major outbreak, with 185 confirmed cases,
12765-551: Was ended in November 2016. As of 2016 there was no available vaccine. Development was a priority of the US National Institutes of Health (NIH), but officials stated that development of a vaccine could take years. To speed new drug development regulatory strategies were proposed by the WHO and NIH. Animal and early human studies were underway as of September 2016. As of December 2019, there were several vaccine candidates in various stages of development. Disease control in
12880-516: Was identified by Simpson in 1964, who was himself infected while isolating the virus from mosquitoes. From then until 2007, there were only 13 further confirmed human cases of Zika infection from Africa and Southeast Asia. A study published in 2017 showed that the Zika virus, despite only a few cases were reported, has been silently circulated in West Africa for the last two decades when blood samples collected between 1992 and 2016 were tested for
12995-444: Was in 2017. Most people who are infected have no or few symptoms. Otherwise the most common signs and symptoms of Zika fever are fever , rash , conjunctivitis (red eyes), muscle and joint pain , and headache, which are similar to signs and symptoms of dengue and chikungunya fever. The time from a mosquito bite to developing symptoms is not yet known, but is probably a few days to a week. The disease lasts for several days to
13110-498: Was reported in 2007 in the Yap Islands of the Federated States of Micronesia. A total of 108 cases were confirmed by PCR or serology and 72 additional cases were suspected. The most common symptoms were rash, fever, arthralgia, and conjunctivitis, and no deaths were reported. The mosquito Aedes hensilli , which was the predominant species identified in Yap during the outbreak, was probably
13225-494: Was reported in all the countries of Asia except Brunei, Hong Kong, Myanmar and Nepal. Serological surveys have indicated that Zika virus is endemic in most areas of Asia, though at a low level. While there was a sharp rise in the number of cases of Zika detected in Singapore after the 2016 Summer Olympics in Brazil, genetic analysis revealed that the strains were more closely related to strains from Thailand than from those causing
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