How long is someone infectious after a viral infection?

How long is someone infectious after a viral infection?

How long is someone infectious after a viral infection?

 

[Original article on NHS Choices website]

The length of time you’re infectious for after having a viral infection depends on the type of virus involved. The infectious period often begins before you start to feel unwell or notice a rash.

The infectious periods for some common viral infections are described below.

Bronchitis

The length of time that bronchitis is infectious varies, depending on its cause. In most cases, bronchitis is caused by the same viruses that cause the common cold or flu and you’re likely to be infectious as long as you have cold or flu symptoms.

Chickenpox

Chickenpox is infectious from about one to two days before the rash appears until all the blisters have fully crusted or scabbed over. This is usually five to six days after the start of the rash.

Common cold

The common cold is infectious from a few days before your symptoms appear until all of the symptoms are gone. Most people will be infectious for around two weeks.


Symptoms are usually worse during the first two to three days and this is when you’re most likely to spread the virus.

Flu (influenza)

Flu is usually most infectious from the day your symptoms start and for a further three to seven days. Children and people with lowered immune systems may be infectious for a few days longer.

Glandular fever

Glandular fever is infectious during the incubation period (the time between catching the virus and developing the symptoms). For glandular fever, this can be two to four weeks.

Some people have the virus in their saliva for a few months after recovering from glandular fever, and may continue to have the virus in their saliva on and off for years. However, glandular fever isn’t very infectious and the length of time people remain infectious varies considerably.

Measles

Symptoms of measles appear around 10 days after you become infected. Measles is most infectious after the first symptoms appear and before the rash develops.

First symptoms of measles include:

a high temperature
red eyes
sensitivity to light
cold-like symptoms – such as a runny nose, watery eyes, swollen eyelids and sneezing




Around two to four days later, a red-brown spotty rash develops that normally fades after about a week.

Mumps

Mumps causes your salivary glands to swell. These glands are just below and in front of your ears. Mumps is most infectious from a few days before your glands swell until a few days afterwards.

Rubella (German measles)

Rubella is infectious for one week before the rash appears and for up to four days afterwards.

You should stay away from school or work for six days after the rash starts to avoid infecting others and try to avoid contact with pregnant women during this time.

Shingles

Shingles is infectious from when the rash first appears until the last blister has scabbed over. This is usually after about 10-14 days.

Tonsillitis

Tonsillitis itself isn’t contagious but the viruses that cause it are. The length of time you’re infectious will depend on the virus. Read more on the causes of tonsillitis.

The Zika Virus – frequently asked questions with Professor John Oxford

Professor John Oxford

Professor John Oxford

“The Zika virus was first isolated in 1947 from a monkey in the Zika forest of Uganda. Its historical home has been in a narrow equatorial belt stretching across Africa and into equatorial Asia.

For decades, the disease, transmitted by the Aedes genus of mosquito, slumbered, affecting mainly monkeys. In humans, Zika occasionally caused a mild disease of low concern.

In 2007, Zika expanded its geographical range to cause the first documented outbreak in the Pacific islands, in the Federated States of Micronesia. From 2013-2014, 4 additional Pacific island nations documented large Zika outbreaks.

In French Polynesia, the Zika outbreak was associated with neurological complications at a time when the virus was co-circulating with dengue. That was a unique feature, but difficult to interpret.

The situation today is dramatically different. Last year, the virus was detected in the Americas, where it is now spreading explosively. As of today, cases have been reported in 23 countries and territories in the region.

The level of alarm is extremely high.


Arrival of the virus in some places has been associated with a steep increase in the birth of babies with abnormally small heads and in cases of Guillain-Barre syndrome.

A causal relationship between Zika virus infection and birth malformations and neurological syndromes has not yet been established, but is strongly suspected.

The possible links, only recently suspected, have rapidly changed the risk profile of Zika, from a mild threat to one of alarming proportions. The increased incidence of microcephaly is particularly alarming, as it places a heart-breaking burden on families and communities.

WHO is deeply concerned about this rapidly evolving situation for 4 main reasons:
• the possible association of infection with birth malformations and neurological syndromes
• the potential for further international spread given the wide geographical distribution of the mosquito vector
• the lack of population immunity in newly affected areas
• and the absence of vaccines, specific treatments, and rapid diagnostic tests.

To find out more Patient Talk interviewed Professor John Oxford.  Professor Oxford is Emeritus Professor of Virology at the University of London, founder of Retroscreen Virology, a leader in the field of vaccine and anti-viral clinical trials for the last 20 years. He is also co-author of Human Virology, Chair of the Global Hygiene Council and regarded as the UK’s leading expert on influenza.

Patient Talk– So John what is the Zika Virus?

Professor John Oxford – Well it’s a pretty globally important virus, it’s a virus that we have kind of known about in theory since about 1948. But since it’s been a very mild virus in Africa anyway we kind of not thought about it at all and then suddenly it’s knocked us between the eyes because of this appearance of the virus in South America and it’s there in large numbers, if I can put it that way, big outbreaks that were not noticed during its history in Africa so suddenly it’s come upon us in a dramatic way and then on top of all of that I mean that we know its spread by Mosquitos but on top of all that it’s the realisation for the first time that this virus can cross the placenta on a pregnant women and can cause serious effects on the developing baby.

Patient Talk – So what are the type of main symptoms from the infection?

Professor John Oxford – The actual infection in most people is hardly noticeable, it’s one of those viruses, I mean Rubella is a related virus that we know more about in Europe and that is the same really, a 2 day rash, not feeling very well but getting better again, it’s not much more than that in its general the way it impacts on the community but like rubella it has this awful tendency, the ability, to effect pregnant women and that is why the world health organisation has declared this a medical emergency of global proportions.

Patient Talk – Ok so what is like the main preventions or how is the kind of symptoms treated?

Professor John Oxford-   The main prevention for this sort of virus is it is mosquito born so 99.9% of the cases that you see in South America are spread by the Aegypti mosquito, it also means the areas where the mosquito not sustained, for example the United Kingdom and most parts of northern Europe as it’s just too cold for a mosquito , so that means we are never going to get a natural transmission of the virus in our area  but in southern areas, like southern France and Southern Italy, you could get the virus coming along and cause problems but its main focus is that they are in south America so the important thing is to break the chain  of transmission and that is by destroying the mosquito  ?? there is a free flying female mosquito that causes the problem or an egg or the lava, you have got to crush absolutely that mosquito, that is the main way of it. Now there is a secondly problem here as well and that is when you get infected, about 5 days after you are infected the virus gets into the blood and into every fluid and that means that it gets into the seminal fluid and that means if you have sex it can transfer sexually as well but that is only in a variant minuet of people compared to the number of people that get bitten by mosquitos and get the infection.

Patient Talk – So how is it treated if the infection is contracted by another human being?

Professor John Oxford – You can’t treat it, unfortunately and I hate to say this but once you get infected by the mosquito you just have to pan it out and do your best now it’s the same with the foetus and we are talking quite high numbers here because a mosquito born virus can easily affect millions of people quite quickly and remember this virus it’s a new territory, south America is a new territory for them and they have not seen it before, so that means they are also sceptical in a way so you could get large numbers of people and if you get millions of people infected over a year say you could work out how many of those are going to get pregnant and you will soon begin to detect numbers of foetal problems you know getting into the several thousand at least I would have thought and just as we are unprotected from the virus so is a developing baby undetected but unlike us where the infection is only mild the infection of the developing baby is not mild because the virus goes into the brain of the developing child in the uterus and can cause serious mental retardation, everything you can think about and more probably.

Patient Talk – So I know you mentioned there about South America being the most hit country in the world but is there any other areas in the world that it is hitting quite severely?

Professor John Oxford – Its hitting all off South America all the countries so in a way it sounds a little but more dramatic and perhaps it is because I know the world health organisation talks about the 94/95 countries but they are all there in south and Middle America. The virus is sometimes like an exotic plants, you know you go to south America and you see a lovely plant you will bring it back to north London in your garden and it just doesn’t grow, and that’s what happens, this virus likes the south America it like the climate, the warmth, the mosquitos everything just fits so that is why the epicentre of it, it will not spread to countries unless they have got large numbers of the Aegypti mosquito.

Patient Talk – Ok fantastic and what is your take on World Health Organisation response to this Zika Virus?

Professor John Oxford – I think the World Health Organisation has responded well to this outbreak know there’s always the subject of everyone criticising but they have got a lot do in other great infections and I think that they are doing well and have reacted pretty fast. Governments are doing pretty well as well I mean the south American and Brazilian government in particularly, they have brought the army in there are pictures everywhere with the army men and women out spraying to kill these mosquitos. But I think other people and other groups have responsibilities, academics like myself and there is going to be a new sharing of scientific data among academics which would lead more quickly to a vaccine. Companies have a role, they employ people, they are international and I was very pleased to see RB for example today declaring they are going to help here with the million dollars which is a huge contribution and a very nice one as well and the expectation is that other companies with join in and donate and that would be wonderful and then finally people themselves have got responsibilities here, we almost forget that and particularly here I think that if for example you or I go to Brazil this year we will have huge responsibilities not to get infected and we must keep away from mosquitos use anti- repellent for example , make sure we are not getting bitten and on top of that though even when we come back to England when you have sex with someone you have got to use a condom because it is remotely possible that you have been infected without knowing about it you can catch the virus and spread it sexually so there is an extra responsibility for men I think when they come back from south America, so yes with everyone working together, academics, the ??, the governments, private companies and people themselves then I think we are going to get somewhere.

Patient Talk – John where can people go for more information?

Professor John Oxford – Well there is a lot of good information on the website, there is public health England, the world health organisation, I mean you name it there will be it, there’s probably more information than we can deal with but the important thing is is that we act on this information, there’s no good spending hours reading it all and then going away and not remembering all of the information it’s when these things will be asked we all have to have responsibilities that’s the important thing we need to realise.