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Other types of infection and transmission Zika challenge scientists
Marina Wentzel
from Basel (Switzerland) to the BBC Brazil
March 11, 2016
The discovery that perhaps the mosquito Aedes aegypti is not the main virus propagation vector Zika and the spread by sexual contact is more common than previously thought put into question all that was known about the zika.
At least that's said scientists and health officials present at the meeting of the World Health Organization (WHO) in Geneva this week.
"It is the only vector Aedes? Well, I can tell you that the world's scientists are beginning to ask questions," said WHO Director-General Margaret Chan. "It may be another species that is causing this? At this point it are scientific gaps. We must continue to find evidence and we have no definitive answers yet."
"This is very surprising. We know that Classically these flavivirus (genus to which they belong virus yellow fever, dengue, chikungunya and zika) are transmitted with a major vector that are the mosquitos Aedes and now we are surprised (with the information) that perhaps other (mosquitoes) are also vectors, "he told BBC Brazil Jorge Kalil, president of the Butantan Institute, who was in wHO meeting on the topic zika.
Doubts about the role of Aedes gained resonance in the scientific community with two studies released last week pointing to the possible involvement of other vectors in the rapid spread of Zika.
The first study, a partnership between the Oswaldo Cruz Institute, Fiocruz, in Rio, with the Pasteur Institute, France, assessed the vector competence of mosquitos Aedes while zika transmitters in five regions: Brazil, United States, and overseas territories French Martinique, Guadeloupe and French Guiana.
Samples of Aedes aegypti and Aedes albopictus were exposed to Zika and monitored in three ways to estimate the potential for transmitting the virus.
First, there was the infection rate, which is indicative of the ability of the virus to invade and replicate in the epithelial cells of the intestine of the mosquito.
Then, the spread was observed rate, which shows if there is the presence of the virus in other parts of the body.
Finally, it was investigated in the presence of zika insect saliva, which is the target point of the cycle has been completed and the mosquito is ready to transmit the disease to poke a human.
The conclusion was that the capacity of Aedes aegypti Zika virus present in saliva is reduced. Of every hundred Aedes aegypti mosquitoes infected in just twenty virus reaches the final stage, reaching the saliva, which makes them able to transmit the virus.
In the case of dengue, for example, every one hundred infected mosquitoes, 40 viewed transmitters. Now chikungunya the rate is even greater: 70 per hundred.
"We can not rule out the possibility that there are more transmission routes through other vectors or directly from one person to another through body fluids," said research coordinator Ricardo Louren?o in a statement.
Culex
The second study, also from Fiocruz but Recife, still in progress, has also surprising data. Led by entomologist Constancia Ayres, research has exposed two hundred common mosquitoes, the type Culex , the zika and recorded a high presence of the virus in insects.
"We find very high levels of infection for the Culex in the gut and saliva. This is a laboratory evidence of susceptibility of Culex to infection and transmission," he told BBC Brazil Ayres.
Now, to prove the theory, it is necessary to replicate the test at least ten thousand samples and also find mosquitoes infected with zika the environment.
"We have a partnership with the health department. The agents are collecting samples in homes that have zika notification and sending to our laboratory." The study should be completed within eight months.
"It is a consensus the fact that we still do not know the basic mechanisms of transmission, not sure about what is the importance of sexual transmission, if there is in fact the transmission by saliva. These are basic questions that we do not yet have how to respond, "summarized Ayres.
Sexual transmission
The first documented transmission Zika by sexual contact occurred in 2008 when an American doctor passed the disease to his wife after returning from a trip to Senegal. The patient maintained relations with the partner, who then presented the symptoms of zika. Tests on blood samples confirmed the presence of the disease.
With the current epidemic, the Centers for Disease Control and Prevention (CDC) of the United States began to monitor possible cases of infection through sex. According to the CDC, the virus remains present for longer in semen than in blood.
During the first month of February, the center has received 14 reports of possible transmissions. Of these, two cases were laboratory confirmed and four were considered probable. All the infected people were women whose partners have recently returned from regions affected by the epidemic.
According to WHO data, sexual transmission cases have also been reported in France and Italy.
"This is a very unexpected transmission feature a flavivirus," he told BBC Brazil Jonas Schmidt-Chanasit, Bernard-Noch Institute of Tropical Medicine in Hamburg.
Schmidt-Chanasit states that it is not common to viruses of this family present transmission through sexual contact and that there may be many open questions about what is known about them.
"I do not exclude, for example, that there is sexual transmission also to diseases such as dengue, the Eastern Nile fever and others, however, has not been observed in this way."
"You could argue that there was not enough research looking for sexual transmission for these viruses, and now, because of zika, there is this image biased. I do not exclude it, but (sexual transmission) in other flaviviruses is not a common feature" , said.
"The virus dispersion pattern is even typical of a transmission by mosquitoes and not by sexual contact. If you look at Brazil, for example, if a sexually transmitted disease would spread to other areas, but it seems that no, that is present even where there is concentration of the vector and not, for example, in southern Brazil ", said Schmidt-Chanasit.
According to updates published by WHO on Thursday, states like Santa Catarina and Parana no reported cases of the disease.
Saliva and breastfeeding
In February Fiocruz identified the active presence of Zika in saliva and urine. At the time, the bank's chairman, Paulo Gadelha, said that "the fact that there is an active virus infection capacity in urine and saliva is no proof yet. And not necessarily mean that the will or that there is possibility of infection others in a systemic way through these fluids. "
In a statement Thursday, the WHO does not recognize breastfeeding as transmission risk factor. Also, the CDC states that there were no reported cases. Based on this, the recommendation is that mothers do not discontinue nursing.
The proven way to mother-child infection occurs during pregnancy and at birth. Blood transfusions are also a form of possible contagion.
"We do not know whether, even though the virus is in the saliva or breastfeeding, it can be absorbed by the gastro-intestinal system (...) involving a series of enzymes and defense systems. The virus is present in all liquids body, but now we need to see the observation is a mother who is breastfeeding can transmit Zika for the child, "Kalil said.
The strategic response plan to the disease launched by WHO in February ranks among the research priorities to understand the proliferation of mechanisms such as co-movement with other pathogenic agent, potential forms of transmission with immune response and complications.
"There's still really a lot to us to know how Zika works, but we progressed a lot in the last two or three months. We are all trying to understand," concludes Kalil.
http://www.bbc.com/portuguese/noticias/2016/03/160303_zika_transmissao_mw
---------------------------------------------------------------------------------------------------------
Related studies:
Eurosurveillance : Isolation of Infectious Zika Viirus From Saliva and Prolonged Viral RNA Shedding in a Traveller Returning From the Dominican Republic to Italy, January 2016
https://flutrackers.com/forum/forum...-the-dominican-republic-to-italy-january-2016
Study: Differential Susceptibilities of Aedes aegypti and Aedes albopictus from the Americas to Zika Virus
https://flutrackers.com/forum/forum...es-albopictus-from-the-americas-to-zika-virus
Culex mosquito may be able to carry Zika virus
https://flutrackers.com/forum/forum...ulex-mosquito-may-be-able-to-carry-zika-virus
Transmission of Zika Virus Through Sexual Contact with Travelers to Areas of Ongoing Transmission ? Continental United States, February 26, 2016
https://flutrackers.com/forum/forum...-—-continental-united-states-february-26-2016
Other types of infection and transmission Zika challenge scientists
Marina Wentzel
from Basel (Switzerland) to the BBC Brazil
March 11, 2016
The discovery that perhaps the mosquito Aedes aegypti is not the main virus propagation vector Zika and the spread by sexual contact is more common than previously thought put into question all that was known about the zika.
At least that's said scientists and health officials present at the meeting of the World Health Organization (WHO) in Geneva this week.
"It is the only vector Aedes? Well, I can tell you that the world's scientists are beginning to ask questions," said WHO Director-General Margaret Chan. "It may be another species that is causing this? At this point it are scientific gaps. We must continue to find evidence and we have no definitive answers yet."
"This is very surprising. We know that Classically these flavivirus (genus to which they belong virus yellow fever, dengue, chikungunya and zika) are transmitted with a major vector that are the mosquitos Aedes and now we are surprised (with the information) that perhaps other (mosquitoes) are also vectors, "he told BBC Brazil Jorge Kalil, president of the Butantan Institute, who was in wHO meeting on the topic zika.
Doubts about the role of Aedes gained resonance in the scientific community with two studies released last week pointing to the possible involvement of other vectors in the rapid spread of Zika.
The first study, a partnership between the Oswaldo Cruz Institute, Fiocruz, in Rio, with the Pasteur Institute, France, assessed the vector competence of mosquitos Aedes while zika transmitters in five regions: Brazil, United States, and overseas territories French Martinique, Guadeloupe and French Guiana.
Samples of Aedes aegypti and Aedes albopictus were exposed to Zika and monitored in three ways to estimate the potential for transmitting the virus.
First, there was the infection rate, which is indicative of the ability of the virus to invade and replicate in the epithelial cells of the intestine of the mosquito.
Then, the spread was observed rate, which shows if there is the presence of the virus in other parts of the body.
Finally, it was investigated in the presence of zika insect saliva, which is the target point of the cycle has been completed and the mosquito is ready to transmit the disease to poke a human.
The conclusion was that the capacity of Aedes aegypti Zika virus present in saliva is reduced. Of every hundred Aedes aegypti mosquitoes infected in just twenty virus reaches the final stage, reaching the saliva, which makes them able to transmit the virus.
In the case of dengue, for example, every one hundred infected mosquitoes, 40 viewed transmitters. Now chikungunya the rate is even greater: 70 per hundred.
"We can not rule out the possibility that there are more transmission routes through other vectors or directly from one person to another through body fluids," said research coordinator Ricardo Louren?o in a statement.
Culex
The second study, also from Fiocruz but Recife, still in progress, has also surprising data. Led by entomologist Constancia Ayres, research has exposed two hundred common mosquitoes, the type Culex , the zika and recorded a high presence of the virus in insects.
"We find very high levels of infection for the Culex in the gut and saliva. This is a laboratory evidence of susceptibility of Culex to infection and transmission," he told BBC Brazil Ayres.
Now, to prove the theory, it is necessary to replicate the test at least ten thousand samples and also find mosquitoes infected with zika the environment.
"We have a partnership with the health department. The agents are collecting samples in homes that have zika notification and sending to our laboratory." The study should be completed within eight months.
"It is a consensus the fact that we still do not know the basic mechanisms of transmission, not sure about what is the importance of sexual transmission, if there is in fact the transmission by saliva. These are basic questions that we do not yet have how to respond, "summarized Ayres.
Sexual transmission
The first documented transmission Zika by sexual contact occurred in 2008 when an American doctor passed the disease to his wife after returning from a trip to Senegal. The patient maintained relations with the partner, who then presented the symptoms of zika. Tests on blood samples confirmed the presence of the disease.
With the current epidemic, the Centers for Disease Control and Prevention (CDC) of the United States began to monitor possible cases of infection through sex. According to the CDC, the virus remains present for longer in semen than in blood.
During the first month of February, the center has received 14 reports of possible transmissions. Of these, two cases were laboratory confirmed and four were considered probable. All the infected people were women whose partners have recently returned from regions affected by the epidemic.
According to WHO data, sexual transmission cases have also been reported in France and Italy.
"This is a very unexpected transmission feature a flavivirus," he told BBC Brazil Jonas Schmidt-Chanasit, Bernard-Noch Institute of Tropical Medicine in Hamburg.
Schmidt-Chanasit states that it is not common to viruses of this family present transmission through sexual contact and that there may be many open questions about what is known about them.
"I do not exclude, for example, that there is sexual transmission also to diseases such as dengue, the Eastern Nile fever and others, however, has not been observed in this way."
"You could argue that there was not enough research looking for sexual transmission for these viruses, and now, because of zika, there is this image biased. I do not exclude it, but (sexual transmission) in other flaviviruses is not a common feature" , said.
"The virus dispersion pattern is even typical of a transmission by mosquitoes and not by sexual contact. If you look at Brazil, for example, if a sexually transmitted disease would spread to other areas, but it seems that no, that is present even where there is concentration of the vector and not, for example, in southern Brazil ", said Schmidt-Chanasit.
According to updates published by WHO on Thursday, states like Santa Catarina and Parana no reported cases of the disease.
Saliva and breastfeeding
In February Fiocruz identified the active presence of Zika in saliva and urine. At the time, the bank's chairman, Paulo Gadelha, said that "the fact that there is an active virus infection capacity in urine and saliva is no proof yet. And not necessarily mean that the will or that there is possibility of infection others in a systemic way through these fluids. "
In a statement Thursday, the WHO does not recognize breastfeeding as transmission risk factor. Also, the CDC states that there were no reported cases. Based on this, the recommendation is that mothers do not discontinue nursing.
The proven way to mother-child infection occurs during pregnancy and at birth. Blood transfusions are also a form of possible contagion.
"We do not know whether, even though the virus is in the saliva or breastfeeding, it can be absorbed by the gastro-intestinal system (...) involving a series of enzymes and defense systems. The virus is present in all liquids body, but now we need to see the observation is a mother who is breastfeeding can transmit Zika for the child, "Kalil said.
The strategic response plan to the disease launched by WHO in February ranks among the research priorities to understand the proliferation of mechanisms such as co-movement with other pathogenic agent, potential forms of transmission with immune response and complications.
"There's still really a lot to us to know how Zika works, but we progressed a lot in the last two or three months. We are all trying to understand," concludes Kalil.
http://www.bbc.com/portuguese/noticias/2016/03/160303_zika_transmissao_mw
---------------------------------------------------------------------------------------------------------
Related studies:
Eurosurveillance : Isolation of Infectious Zika Viirus From Saliva and Prolonged Viral RNA Shedding in a Traveller Returning From the Dominican Republic to Italy, January 2016
https://flutrackers.com/forum/forum...-the-dominican-republic-to-italy-january-2016
Study: Differential Susceptibilities of Aedes aegypti and Aedes albopictus from the Americas to Zika Virus
https://flutrackers.com/forum/forum...es-albopictus-from-the-americas-to-zika-virus
Culex mosquito may be able to carry Zika virus
https://flutrackers.com/forum/forum...ulex-mosquito-may-be-able-to-carry-zika-virus
Transmission of Zika Virus Through Sexual Contact with Travelers to Areas of Ongoing Transmission ? Continental United States, February 26, 2016
https://flutrackers.com/forum/forum...-—-continental-united-states-february-26-2016