Our Next Global Health Crisis: Zika Virus Disease and Its Implication on Animals

1. Background

Zika virus disease or Zika is a disease caused by Zika virus that is spread to people primarily through the bite of an infected Aedes species mosquito. The most common or prominent symptoms of Zika are fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting for several days to a week after being bitten by an infected mosquito. People usually don’t get sick enough to go to the hospital, and they very rarely die of Zika. For this reason, many people might not realize they have been infected. Once a person has been infected, he or she is likely to be protected from future infections (CDC, 2016).

Zika virus was first discovered in 1947 and is named after the Zika forest in Uganda. In 1952, the first human cases of Zika were detected and since then, outbreaks of Zika have been reported in tropical Africa, Southeast Asia, and the Pacific Islands. Zika outbreaks have probably occurred in many locations. Before 2007, at least 14 cases of Zika had been documented, although other cases were likely to have occurred and were not reported. Because the symptoms of Zika are similar or resembles to those of many other diseases, many cases may not have been recognized (CDC, 2016).

It has been reported that in May 2015, the Pan American Health Organization (PAHO) issued an alert regarding the first confirmed Zika virus infection in Brazil and on Feb 1, 2016, the World Health Organization (WHO) declared Zika virus a public health emergency of international concern (PHEIC). Local transmission has been reported in many other countries and territories. Zika virus likely will continue to spread to new areas (CDC, 2016).

According to the world health organization report from February 2014 to 17 January 2016, there are 18 countries and territories in the Americas that have confirmed autochthonous circulation of Zika virus (ZIKV) in 2015 and 2016: Brazil, Barbados, Colombia, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Puerto Rico, Saint Martin, Suriname, and Venezuela. Between November 2015 and January 2016, local transmission of the virus was detected in 14 new countries and territories (WHO, 2015).

Zika viral infection disease is a flavivirus transmitted mainly by mosquitos in the genus Aedes, was discovered in 1947 in Uganda. From the 1960s to 1980s, human infections were found across Africa and Asia, typically accompanied by mild illness. The first large outbreak of disease caused by Zika infection was reported from the Island of Yap (Federated States of Micronesia) in 2007, as the virus moved from south-east Asia across the Pacific. During a 2013-14 outbreak in French Polynesia, the neurological disorder Guillain-Barre syndrome was linked to Zika infection. In South America, the first reports of locally transmitted infection came from Brazil in May 2015. In July 2015 Brazil reported an association between Zika virus infection and GBS. In October 2015 Brazil reported an association between Zika virus infection and microcephaly. For neither event was a causal link proven (WHO, 2015).

In 2015 the world health organization reported that in February 2016, as infection moved rapidly through the range occupied by Aedes mosquitos in the Americas, WHO declared that Zika infection associated with microcephaly and other neurological disorders constitutes a Public Health Emergency of International Concern (PHEIC). By the start of February 2016, local transmission of Zika infection had been reported from more than 20 countries and territories in the Americas, and an outbreak numbering thousands of cases was under way in Cabo Verde, western Africa. Beyond the range of mosquito vectors, Zika virus infections are expected to be carried worldwide by international travel (WHO, 2015).

The report further describes that Zika is spread by the Aedes genus of mosquito, which transmits the disease when it bites a person, infected with Zika, then bites another host. The two most common mosquitoes to transmit the disease are the Aedes aegypti and Aedes albopictus species. Both are invasive species with worldwide distributions, including in the American south and south-west. It is believed that Aedes albopictus, also called the Asian tiger mosquito, was imported to the United States in the mid-1980s in used tires from Asia.

Usually, Zika’s symptoms include fever, red and bumpy rash, joint pain and pink eye. Hospitalization rates are low and the World Health Organization said no deaths have been reported from Zika. However, a “high rate” of patients with Zika have no symptoms at all, according to the WHO. This is concerning to virologists, who believe that Zika could easily establish a foothold in the southern United States and other areas with tropical climates because people may not know they are infected.

2. Objective

To asses status Zika virus infection, and its association with animals

3. Methods

Different research outputs, rapid survey results and conference papers were reviewed to address the core issues (Background, objectives, findings and conclusion) of this study.

4. Findings/Literature Review

4.1. Zika virus infection

The world health organization report 2016 describes that Zika virus infection is caused by the bite of an infected Aedes mosquito, usually causing rash, mild fever, conjunctivitis, and muscle pain. The virus was isolated for the first time in 1947 in the Zika forest in Uganda. Since then, it has remained mainly in Africa, with small and sporadic outbreaks in Asia. In 2007, a major epidemic was reported on the island of Yap (Micronesia), where nearly 75% of the population was infected. On 3 March 2014, Chile notified PAHO/WHO of autochthonous transmission of Zika virus on Easter Island, where the virus continued to be detected until June 2014. In May 2015, the public health authorities of Brazil confirmed the transmission of Zika virus in the country’s northeast. Since October 2015, other countries and territories of the Americas have reported the presence of the virus (WHO, 2016).

4.2. Symptoms of zika

Even though the symptom is similar to most other infectious disease, the most common symptoms of Zika virus infection are exanthema (skin rash) and mild fever, usually accompanied by conjunctivitis, muscle or joint pain, and general malaise that begins 2-7 days after the bite of an infected mosquito. One out of four infected people develops symptoms of the disease.

Among those who do, the disease is usually mild and can last 2-7 days. Symptoms are similar to those of dengue or chikungunya, which are transmitted by the same type of mosquito.

The WHO report of 2016 indicated that Neurological and autoimmune complications are infrequent, but have been described in the outbreaks in Polynesia and, more recently, in Brazil. As the virus spreads in the Americas, giving us more experience with its symptoms and complications, it will be possible to characterize the disease better (WHO,2016).

4.3. Mode of transmission of Zika virus

It has been reported so far that Zika virus is transmitted to people through the bite of an infected Aedes mosquito. This is the same mosquito that transmits dengue and chikungunya. Recently other, though less common, modes of transmission have been observed. Zika virus disease is a mosquito-borne disease caused by Zika virus which causes in general a mild febrile illness with maculo-papular rash. Aedes mosquitoes are considered as main vectors. Before 2007, viral circulation and a few outbreaks were documented in tropical Africa and in some areas in Southeast Asia. Since 2007, several islands of the Pacific region have experienced outbreaks (WHO,2016).

The report further indicates that in 2015, Zika virus disease outbreaks were reported in South America for the first time. Zika virus disease is now considered as an emerging infectious disease. A significant increase of patients with Guillain–Barré syndrome (GBS) was reported during the 2014 outbreak in French Polynesia and the Americas since 2015. A similar increase along with an unusual increase of congenital microcephaly was observed in some regions in north eastern Brazil in 2015. Causal relationships are currently under investigation. There is no prophylaxis, treatment or vaccine to protect against Zika virus infection. Therefore, preventive personal measures are recommended to avoid mosquito bites during the daytime (WHO,2016).

4.4. The disease causing agents/ pathogen

The causative agent or pathogen of the Zika virus disease is caused by a virus from the Flavivirus genus, Flaviviridae family, from the Spondweni group. It was first isolated in 1947 from a monkey in the Zika forest, Uganda, then in mosquitoes (Aedes africanus) in the same forest in 1948 and in a human in Nigeria in 1952. There are two Zika virus lineages: the African lineage and the Asian lineage which has recently emerged in the Pacific and the Americas (Hayes, 2009 and Fayo et al; 2014).

4.5. Incubation period and disease symptom

According to the European Center for disease control report 2016, the incubation period ranges between approximately three to 12 days after the bite of an infected mosquito. Most of the infections remain asymptomatic (approximately 80%). Disease symptoms are usually mild and the disease in usually characterised by a short-lasting self-limiting febrile illness of 4–7 days duration without severe complications, with no associated fatalities and a low hospitalization rate. The main symptoms are maculopapular rash, fever, arthralgia, fatigue, non-purulent conjunctivitis/conjunctival hyperaemia, myalgia and headache. The maculopapular rash often starts on the face and then spreads throughout the body. Less frequently, retro-orbital pain and gastro-intestinal signs are present (ECDC, 2016).

The report further describes that Congenital central nervous system malformations such as microcephaly in fetuses and newborns from mothers possibly exposed to Zika virus during pregnancy were notified during recent Zika disease outbreaks (French Polynesia and Brazil). Unusual increases of Guillain–Barré syndrome were reported in several countries in the Americas and French Polynesia coinciding with the Zika virus outbreak. Further evidence is needed to establish a causal link between Zika virus infection and these neurological/neurodevelopmental impairments or auto-immune conditions (ECDC, 2016).

4.6. Epidemiology

According to some reports serological surveys in Africa and Asia indicate a most likely silent Zika virus circulation with detection of specific antibodies in various animal species (large mammals such as orangutans, zebra, elephants, water buffaloes) and rodents. The knowledge of geographical distribution of Zika virus is based on results of serosurveys and viral isolation in mosquitoes and humans, and with reports of travel-associated cases. Before 2007, the areas with reported Zika virus circulation included tropical Africa and Southeast Asia. Very few outbreaks were documented prior to 2007. An outbreak was reported on Yap Island, Federated States of Micronesia from April to July 2007 (Duffy et al; 2009). This was the first outbreak of Zika virus identified outside of Africa and Asia. Between 2013 and 2015, several significant outbreaks were notified on islands and archipelagos from the Pacific region including a large outbreak in French Polynesia. In 2015, Zika virus emerged in South America with further spread across the Americas (Hayes et al; 2009, Cristiane et al; 2015 and Musso et al;2014).

4.7. How the disease is transmissited

The European Center for disease control report 2016 indicated that Zika virus is transmitted by mosquitoes. It has been isolated from Aedes aegypti mosquitoes and experimental infections show that this species is capable of transmitting Zika virus. Other Aedes mosquito species (notably Ae. africanus, Ae. albopictus, Ae. polynesiensis, Ae. unilineatus, Ae. vittatus and Ae. hensilli) are considered as potential vectors of Zika virus. These species bite during the day. Additional modes of transmission have been identified. Perinatal transmission can occur most probably by trans-placental transmission or during delivery when the mother is infected. Sexual transmission was reported in a few instances. There is a potential risk of Zika virus transmission from a blood transfusion. More information on mosquitoes can be found here: Aedes albopictus and Aedes aegypti (Diallo et al; 2014, Li et al; 2012 and Wong et al; 2013)

4.8. How to Diagnostics Zika

The European Center for disease control report 2016 indicated that Zika virus disease diagnostics is primarily based on detection of viral RNA from clinical specimens in acutely ill patients. The viraemic period appears to be short, allowing for direct virus detection during the first 3–5 days after the onset of symptoms. Zika virus RNA has been detected in urine up to 10 days after onset of the disease. From day five post onset of disease, serological investigations can be conducted by detection of Zika-specific IgM antibodies and confirmation by neutralisation, seroconversion or four-fold antibody titer increase of Zika specific antibodies in paired serum samples. Serological results should be interpreted according to the vaccination status and previous exposure to other flaviviral infections (ECDC, 2016)

4.8. How to treat zika

Until today there is no vaccine or specific prophylactic treatment. Differential clinical diagnostic should be considered as well as co-infection with other mosquito-borne diseases such as dengue fever, chikungunya and malaria. The treatment is symptomatic and mainly based on pain relief, fever reduction and anti-histamines for pruritic rash. Treatment with acetylsalicylic acid and no-steroidal anti-inflammatory drugs was discouraged because of a potential increased risk of haemorrhagic syndrome reported with other flaviviruses as well as the risk of Reye's syndrome after viral infection in children and teenagers (ECDC, 2016)

4.9. Some measures of Public Health Control

According to the European Center for disease control report 2016, no vaccine or prophylactic treatment is available. Integrated vector management aiming to reduce mosquito vector density in a sustainable manner is of primary importance. Intersectoral collaboration and efficient public communication strategies to ensure community participation are required for sustainable vector control program. Activities supporting the reduction of mosquito breeding sites in outdoor/indoor areas by draining or discarding sources of standing water at the community level include removal of all open containers with stagnant water in and surrounding houses on a regular basis (flower plates and pots, used tyres, tree-holes and rock pools), or, if that is not possible, treatment with larvicides), tight coverage of water containers, barrels, wells and water storage tanks, wide use of window/door screens by the population. During an outbreak elimination of adult mosquitoes through aerial spraying with insecticides can be considered. More information on mosquitoes can be found here: Aedes albopictus and Aedes aegypti (ECDC, 2016).

4.10. Mode of infection Control, protection and prevention

It has been reported so far by the European Center for disease control, prevention is also based on protection against mosquito bites. Aedes mosquitoes bite during the daytime both indoors and outdoors. Therefore personal protection measures should be applied during the day. Personal protection measures to avoid mosquito bites should be applied when in risk areas by using appropriate mosquito repellents and wearing long-sleeved shirts and long trousers especially during the hours of highest mosquito activity, sleeping or resting in screened or air-conditioned rooms, otherwise use insecticidal treated mosquito nets, even during the day, removing mosquito breeding sites in close outdoor/indoor premises (ECDC, 2016)

The report further indicate that Use of mosquito repellent in accordance with the instructions indicated on the product label. Travellers with immune disorders or severe chronic illnesses should consult their doctor or seek advice from a travel clinic before travelling, particularly on effective prevention measures. Similar protective measures apply to a symptomatic patient in order to prevent transmitting the disease to non-infected mosquitoes. More information on mosquitoes can be found here: Aedes albopictus and Aedes aegypti (ECDC, 2016)

4.2. Cross Cutting issues with Zika Virus Infection

Can zika transmitted through donated blood?

According to WHO report currently there is limited knowledge of Zika virus and the ways it can be transmitted. However, the following suggest it may present a risk to blood safety: The virus has been detected in blood donors in areas where Zika is circulating Transmission of related viruses (dengue, chikungunya and West Nile virus) by blood transfusion has been documented, and thus transmission of Zika virus is possible (WHO, 2016).

Brazilian health authorities have reported 2 cases of possible transmission of the virus by blood transfusion. Studies are needed to assess the prevalence of the virus and of transmission through blood transfusion and blood products to better understand the risk Zika presents. What precautions should be taken to ensure that the blood supply is safe in countries where Zika infection is occurring?

Specific measures recommended preventing Zika infection should be part of an overall blood strategy based on the guidelines in PAHO’s Plan of Action for Universal Access to Safe Blood 2014-2019 for strengthening national blood programs. These guidelines recommend:

Well organization of blood services

Further Implementation of quality management programs throughout the transfusion chain and ensuring Good Manufacturing Practices; Ensuring that blood donation is voluntary, repeated, and from low-risk populations, and eliminating mandatory replacement donation; Ensuring the appropriate use of blood and blood products; Providing continuous training for blood services staff and blood products users, Providing health surveillance, hem vigilance, and risk management (WHO, 2016).

Ideally the blood supply during a regional outbreak of Zika should be maintained by increasing blood collections in non-affected areas. In non-affected areas, consideration may be given to deferring potential donors who have recently visited areas with ongoing transmission of Zika virus infection for 28 days after their departure from these areas (WHO, 2016)..

Is sexual intercourse the possible transmission of Zika?

The WHO 2016 report indicated that the most common form of Zika transmission is through mosquito bites, but the virus has been isolated in semen, and cases of sexual transmission have been observed. Currently the available evidence is being analyzed to better understand the public health impact of sexual transmission of Zika. The IHR Emergency Committee on Zika virus, at its meeting March 8, 2016, said, that pregnant women should be advised not travel to areas of ongoing Zika virus outbreaks; pregnant women whose sexual partners live in or travel to areas with Zika virus outbreaks should ensure safe sexual practices or abstain from sex for the duration of their pregnancy (WHO,2016).

What can be done to prevent sexual transmission?

The world health organization recommended that all patients (male and female) with Zika virus infection and their sexual partners’ particularly pregnant women) should receive information about the potential risks of sexual transmission of Zika virus, contraceptive measures and safer sexual practices, and should be provided with condoms when feasible. Women who have had unprotected sex and do not wish to become pregnant because of concern with infection with Zika virus should also have ready access to emergency contraceptive services. Sexual partners of pregnant women, living in or returning from areas where local transmission of Zika virus is known to occur, should use safer sexual practices or abstinence from sexual activity for the duration of the pregnancy (WHO, 2016).

Is there possible transmission from mother to child?

There is growing evidence that this type of transmission is possible. Research is currently under way on possible mother-to-child transmission of the virus and its effects on babies. Pregnant women in general, and particularly those who develop symptoms of Zika virus infection, should be closely monitored by health providers (WHO, 2016).

Can Zika have treatment?

Until today there are no any treatments except treatment consists of relieving pain, fever, and any other symptom that inconveniences the patient. To prevent dehydration, it is recommended to control the fever, rest, and drink plenty of water. There is no vaccine or specific drug for this virus (WHO, 2016).

Is zika cause death?

There is no any report of death so far. Since Zika is a new virus for the Region of the Americas. In the past, it had very limited geographical and demographic distribution, and there was no evidence that it caused death. However, in the current outbreak, sporadic cases have been reported of more serious manifestations and complications that have sometimes resulted in death (WHO, 2016).

Who is at risk of Zika infection?

According to the WHO report anyone not previously exposed to the virus and who lives in an area where the mosquito is present, and where imported or local cases have been reported, may be infected. Since the Aedes mosquito is found throughout the Region (except in continental Chile and Canada), it is likely that outbreaks will occur in other countries that have not yet reported any cases (WHO, 2016).

How is Zika diagnosed?

The diagnosis of the zika is based on clinical symptoms and epidemiological circumstances (such as Zika outbreak in the patient’s area or trips to areas where the virus is circulating). Blood tests can help to confirm the diagnosis. Some (virological PCR tests) are useful in the first 3-5 days after the onset of symptoms, while others (serological tests) detect the presence of antibodies but are useful only after five days. Once it has been demonstrated that the virus is present in a given area or territory, confirmation of all cases is not necessary, and laboratory testing will be adjusted to routine virological surveillance of the disease (WHO, 2016).

Can people with Zika pass the illness to others?

It has been believed that for transmission Zika needs a vector (a means of transportation) to infect people; generally, that vector is the mosquito. However, Zika virus has been found in semen and person-to-person sexual transmission has been documented. Travelers to an area with Zika should continue to take steps to prevent mosquito bites for 3 weeks after they leave the Zika-affected area to avoid spreading the virus, even if they do not feel sick. Only one in five infected people develop symptoms. Zika virus can be found in the blood of an infected traveler and passed to another mosquito through mosquito bites. An infected mosquito can then spread the virus to other people (WHO, 2016).

Zika virus and Animals

According to some reports a lot of questions have been raised about Zika virus and animals. It’s great to see that people are thinking more broadly about infectious diseases (but it isn’t doing much for my productivity this week). To recap, Zika virus is a mosquito-borne virus related to West Nile virus and dengue virus. Most people that are infected don’t get sick at all, and when they do, they usually get only mild signs of illness that resolve on their own. In the past few years, Zika virus has emerged in the Americas, particularly Brazil. Very recently, a link (still unproven) between infection of pregnant women and birth defects (babies born with small heads and brains (microcephaly)) has been reported, predominantly in Brazil (Worms and Germs, 2016)

Can animals get infected with Zika virus?

Frankly speaking it depends on what you include in “animals.” We could be technical and say that humans are animals. Beyond that, non-human primates are susceptible. Zika was first identified in 1947 when yellow fever researchers working in the Zika forest in Uganda stumbled onto it. They had a macaque in a cage and it developed a febrile illness from something that was transmissible. The virus was described as Zika virus in 1952 and then found in people a couple of years later (Worms and Germs, 2016).

Can domestic animals get infected with Zika virus?

Again, we need further to think about the question. According to Worms and Germs report of 2016, infected means they get exposed to the virus and it replicates in the body. That may occur, but we don’t have any evidence of it at this point. The more relevant question is whether animals can get sick from Zika virus exposure, and there’s also no evidence of that to date. A third aspect is whether infected (but potentially healthy) animals could be a reservoir for the virus, being able to pass it on to mosquitoes. There’s no evidence of that, either (Worms and Germs, 2016).

So, according to this report the clearest answer is probably “maybe.” When it was a flu-like illness confined to some regions in Africa, Zika wasn’t a high priority so research hasn’t been extensive. The risk to pets in areas where the virus is circulating (areas where there are Aedes egpyti and Aedes albopictus mosquitoes) is probably very low. It would be good to look into the risks associated with domestic animals, including their susceptibility to disease and potential roles as reservoirs, but the likelihood that there is a relevant issue with either of these is probably remote.

Is there risk for Horses?

Some report suggests that there’s currently no evidence that Zika virus can infect horses. Zika which is a mosquito-borne virus related to West Nile virus and dengue fever has only been found in nature in humans and nonhuman primates. It’s possible that horses could be exposed if they live in areas where infected Aedes egyptii or Aedes albopictus mosquitoes are present; however, exposure doesn’t necessarily mean disease. For example, a horse could be exposed to a person with chickenpox but wouldn’t get sick because the chickenpox virus is unable to infect horses. As far as we know, Zika virus is the same, but this hasn’t received any research of which I’m aware.

While we can’t yet say there’s no risk, it’s reasonable to assume that the likelihood of Zika virus infecting horses and causing serious disease is low. Now that Zika virus has emerged in areas where horses are common, there researchers will hopefully study whether this virus can infect horses. In the unlikely event that Zika virus does cause disease in horses it would probably mainly cause mild disease, with fever and other general signs that go away on their own. The main concern in people is a link to birth defects (specifically microcephaly, or the abnormal smallness of the head with incomplete brain development), something that still needs to be proven. There’s no indication that Zika-associated birth defects occur in species other than humans.

Is pets affected by Zika?

According to the center for disease control report the once-obscure Zika virus is now making daily headlines as it surfaces in more countries and health officials rush to make recommendations to keep it from spreading. We know the virus is primarily spread by mosquitoes. Only about one in five people infected with Zika virus will get sick, according to the Centers for Disease Control and Prevention, and even then the symptoms are usually mild. However, the disease has been linked to serious birth defects and other major health problems. We know it is of most concern to pregnant women and there is at least one case of it being spread by sexual contact (MNN, 2016).

In his speech Chris Barker, a researcher in the School of Veterinary Medicine’s Department of Pathology, Microbiology, and Immunology at the University of California, Davis said that "I think unless you're talking about pet monkeys, which should be extremely rare cases, as far as dogs and cats, I don't know of any information or scientific studies on that topic,". Barker studies the epidemiology of mosquito-transmitted diseases. Of two common mosquito species that spread Zika Aedes aegypti and Aedes albopictus the former prefers biting humans and the latter has a broader palate. CDC researcher Roberto Barrera found that up to 20 percent of bites from the Aedes aegypti mosquito in several rural communities in Puerto Rico were on dogs (MNN, 2016).

He further suggests that "Certainly there's the potential for a pet to become infected,". "What we don't know is what that means for the health of the animal." If a dog or cat were to become infected, we also don't know if they could spread the virus to humans. "What would ultimately matter in terms of whether a pet would play a role in transmission is how much virus would be in the animals' blood," Barker says. Although there have been no cases of Zika being transmitted via mosquito in the United States, the mosquitoes that are capable of transmitting the virus do live in the U.S. So one of the best ways to protect people (and pets) from possible infection is to practice good mosquito control on your property (MNN, 2016).

"Encourage people to limit mosquito production from their own backyards, and they should encourage their neighbors to do the same. That's one of the best measures we can take," says Barker. "Where we do have the mosquitoes, we want to do everything we can to minimize the mosquitoes and limit the transmission risk." (MNN, 2016).

What will be expected in the near future?

Can we get vaccinate against zika?

Until the future The short and official answer? No. “There are no licensed vaccines against the Zika virus anywhere in the world,” said Lucey. The Brazilian government has recently announced that it will fund efforts to develop a vaccine in “record time,” according to the Health Minister Marcelo Castro which is expected to take three to five years. According to Lucey, an effort led by the National Institutes of Health to develop a Zika vaccine has also only recently begun (GLP, 2016).

However there is some good news. Nikos Vasilakis of the University of Texas Medical Branch said, “Given the existence of highly successful and efficacious vaccines against yellow fever and Japanese encephalitis viruses, which are closely related to Zika virus, development of a live attenuated or chimeric vaccine would be straightforward.” However, Lucey cautioned that expecting that a solution is around the corner might be too optimistic. “Assuming that the scientific and pharmaceutical industry challenges can be met as quickly as possible, based on past new vaccine development timelines, we are several years away from having an FDA-licensed Zika vaccine,” he said to GENeS (GLP, 2016).

Dose Genetic engineered has solution for zika?

According to the genetic literacy project report the first line of action in almost all cases is to get rid of the mosquitoes and prevent them from breeding further. This involves fumigation and removing sources of stagnant water where mosquitoes can breed. Brazilian authorities have even deployed army troops to hasten this process (GLP, 2016).

The report further indicated that a more biotech based vector control solution is the use of genetically engineered mosquitoes developed by the British firm Oxitec. The modified male Aedes aegeypti mosquitoes mate with females in the wild population and produce offspring that do not survive to adulthood, essentially making the males sterile. Such a mosquito was approved for use in the city of Piracicaba, Brazil last year in the middle of the dengue outbreak and trials showed that they reduced vector populations by as much as 82 percent. Yesterday, Oxitec announced that it was expanding its production facilities in Piricicaba in view of a potentially increased demand to combat dengue and Zika (GLP, 2016)..

It was reported that though a similar trial was proposed in Florida which also has a high Aedes mosquito population, it’s adoption has been controversial in the United States. The FDA is currently reviewing the application for a trial and it is not known whether the rapid spread of Zika and its potential to quickly move to the US will hasten the process in any way. The biological basis of this control strategy is well understood and similar strategies have been used for decades for insects mainly of agricultural significance (GLP, 2016)..

When GENeS asked experts about the expansion plans of Oxitec, the reactions were mostly positive.”In my opinion [it] is generally an encouraging sign that this and related genetics-based technologies for the control or local elimination of mosquitoes is moving towards the mainstream,” said David O’Brochta, a professor of Entomology at the University of Maryland.

Is Zika our next global health crisis?

Definitely yes. Since having survived the human drama of SARS, Avian Flu, Swine Flu, and Ebola - are we now headed for another infectious disease disaster? The Zika virus, rapidly spreading around the world and now detected in Australians returning from South America, may very well turn out to be our next health crisis.The Department of Foreign Affairs and Trade has now issued a new advice warning to Australians, particularly pregnant women, to reconsider plans to travel to 22 countries affected by the virus (Drum,2016)

As noted so far Zika is a mosquito-borne flavivirus, closely related to dengue to which its symptoms are very similar. Like both the dengue and Chikungunya viruses, the disease is transmitted by aedes mosquitoes and results in rashes, fever, headaches and severe joint pain. In the case of Zika only one in five of those infected will go on to develop symptoms but there is a possibility that the infection can produce microcephaly (abnormal smallness of the head) in newly born infants. While the evidence is still not conclusive there is little doubt that the number of young children born with microcephaly has substantially increased in countries such as Brazil where over the last year Zika has spread widely (Drum,2016)

It was pointed out that Zika is named after a forest in Uganda where the disease was first isolated in a rhesus monkey in 1947. It was first found in humans in Nigeria in 1954. Looking back on the last 15 years, have we learnt anything about the identification and control of infectious disease outbreaks? I very much doubt it. Before 2013 only a handful of Zika cases had been recorded but during 2015 the disease spread rapidly, producing a number of significant outbreaks in the Pacific Islands, South America and South East Asia. Recently the infection has also been recorded in Puerto Rico, and cases are now beginning to appear in the USA and UK among travellers returning from Latin America (Drum,2016)

In his study Drum reported that The large-scale outbreak in Brazil, that seems to have commenced in 2015, has virologists linking the infection to the birth defect microcephaly for the first time. In parts of Latin America women are now being advised to postpone becoming pregnant for at least six months. Like many infections, the disease accompanies international travellers around our world, particularly those who had spent time in Latin America or the Pacific Islands. This, allied to the fact that the aedes mosquitoes responsible for spreading dengue throughout the world are also widespread in parts of Australia, places us at risk. Also, like dengue, there is no cure for Zika and treatment simply focuses on relieving the symptoms (Drum, 2016)

However it is still unclear as to why Zika, which until recently was relatively rare, seems to be spreading so quickly. Many believe that human mobility and intrusion into infected areas plays a critical role but some argue that increasing temperatures, changing the breeding pattern and distribution of mosquito populations, may also be to blame. There is little doubt that we are living in a highly mobile world where millions of people move every day across international borders in pursuit of holidays, education and business - or fleeing from natural disasters or civil unrest.

In addition, more people are seeking to visit remote rural locations in Latin America and the Pacific, possibly exposing them to encounters with infected mosquitoes. It would also seem true that both increasing temperatures and a higher frequency of tropical downpours may well influence the number and distribution of aedes mosquitoes.

The study further discuss that but are we witnessing the early stages of a 'pandemic in progress'? If an epidemic of Zika was to break out in Australia, would it produce the same reaction and fear that we saw with SARS and Avian and Swine Flu? Possibly not given that we have been living with dengue for well over 100 years. But on the other hand, the possible implications for mothers giving birth would most certainly engender considerable fear and apprehension. There is little doubt that infectious disease is one of the major challenges facing our world today (Drum, 2016)

Finally given our experience with dengue and other mosquito-borne infections we tend to be governed by the rubric: 'If it kills us, then we do something about it. Whereas, if it just debilitates and incapacitates, we tend to live with it'. If this was untrue we would have had a cure or vaccine for dengue decades ago. Presumably the same might apply to Zika. The ebola outbreak in West Africa also indicated how poorly we react and respond to epidemic crises. The 'standby, wait, and watch' attitude of the developed world seems to be based on a belief that epidemics in underdeveloped countries will eventually burn themselves out and that unless they directly threaten North America or Europe we do not need to react and respond.

Further we still do not have an international response and reaction agency charged with quickly identifying and responding to epidemics wherever they might occur in the world. With respect to infectious disease there is still much we have to do to ensure a safe and secure world (Drum, 2016)

Expectation in the near future?

As a matter of facts there appears to be little chance of Zika slowing down. The US aside, Brazil is expecting to host thousands, if not millions of travelers from around the world first for Carnival in February and then in the 2016 Summer Olympics. It could lead to the rapid spread of Zika to other parts of the world, said some experts, though local officials in Brazil suggest that by then the rainy season would be over, allowing the outbreak to subside. Summer is also when things might ramp up in the US, especially in the southern parts where conditions are more ideal for mosquitoes to breed. Better quality of resources and healthcare may prevent the virus from spreading as fast though. “I anticipate Zika becoming much worse in the near future,” said professor Lucey of Georgetown University (GLP, 2016).

5. Conclusions

Zika virus disease (Zika) is a disease caused by Zika virus that is spread to people primarily through the bite of an infected Aedes species mosquito.

Zika virus was first discovered in 1947 and is named after the Zika forest in Uganda. In 1952, the first human cases of Zika were detected and since then, outbreaks of Zika have been reported in tropical Africa, Southeast Asia, and the Pacific Islands.

Zika is spread by the Aedes genus of mosquito, which transmits the disease when it bites a person, infected with Zika, then bites another host. The two most common mosquitoes to transmit the disease are the Aedes aegypti and Aedes albopictus species.

Usually, Zika’s symptoms include fever, red and bumpy rash, joint pain and pink eye. Hospitalization rates are low and the World Health Organization said no deaths have been reported from Zika.

So far a lot of questions have been raised about Zika virus and animals, however until today except animals anyone not previously exposed to the virus and who lives in an area where the mosquito is present may be infected with the virus.

To answer the question can animals get infected with Zika virus? It depends on what you include in “animals.” we could be technical and say that humans are animals. Beyond that, non-human primates are susceptible.

Again, we need to think about the question. Infected means they get exposed to the virus and it replicates in the body. That may occur, but there is no any evidence of it at this point.

The more relevant question is whether animals can get sick from Zika virus exposure, and there’s also no evidence of that to date. A third aspect is whether infected (but potentially healthy) animals could be a reservoir for the virus, being able to pass it on to mosquitoes. There’s no evidence of that, either. So, the clearest answer is probably “maybe”.

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