Vaccines For Dummies. Sharon Perkins

      Type C usually causes milder illness and is more common in children. Health providers don’t vaccinate against Type C and usually don’t test for it. You may well have had influenza type C in the past and not recognized it, because symptoms are generally mild. People and some animals are susceptible to this strain of influenza.

      Type D

      

Type D is found mostly in cattle and other animals. It has not been found to cause illness in humans, though some people have antibodies to it, meaning that they’ve had some exposure to it. There’s no vaccination against type D influenza.

Examining Enteroviruses (Including Rhinoviruses)

      You’ve probably had an enterovirus case and didn’t even know it. Nine in ten cause no symptoms or just a brief fever without anything remarkable. There are over 80 different types of enteroviruses, and each type has its own footprint. Enteroviruses can cause a common cold; diarrhea; mouth blisters; pink eye; hand, foot, and mouth disease; and even nervous system infections that can lead to paralysis.

      These viruses can cause a severe illness in some, a mild illness in others, and just a fever or nothing at all in still others. Enterovirus D68, just to name one, can cause a cold in some, but for some children, it can cause more severe respiratory illness and can leave lasting nerve damage that causes weakness or even paralysis.

      There are a few different ways to get sick with an enterovirus:

       It often spreads when you don’t wash your hands frequently, especially after using the toilet.

       It can spread by fecal-oral transmission, when you get the tiniest amount of stool from someone else in your mouth, often by touching an infected surface and then putting your hand to your mouth.

       It can spread from having close contact, like shaking hands with someone who hasn’t washed their hands well.

       Directly touching contaminated stool, such as when changing diapers, and then touching your eyes, nose, or mouth can infect you.

       Contact with fluid from blisters that form in hand, foot, and mouth disease can infect you.

       Respiratory droplets can spread enteroviruses. Coughing, sneezing, and breathing can create droplets that spread. Any contact with saliva, sputum, eye secretions, or nasal mucus can spread an enterovirus.

       It can be spread from drinking water with the virus in it, which can occur when tiny amounts of sewage contaminate drinking water, especially where resources are more limited.

      

There’s one type of enterovirus that’s more worrisome than the rest. Polio is an enterovirus. It causes paralysis in a small number of people who are infected. Usually one in 100 or so infected develop paralysis. Others may just have diarrhea or a fever and not the weakness we worry about. Most people are vaccinated against polio, and the disease has been almost eliminated worldwide. Only one of the three initial types is still spreading, and it’s known to be in only a few places.

      Rhinoviruses are another viral species in the same family as enterovirus species, and in fact, they are all in the genera enterovirus. They are the most common cause of the cold. They cause many — up to 50 percent — of the sniffles, coughs, and sore throats that we call the common cold. They spread by droplets from coughs, sneezes, and just plain breathing. They can also spread when you touch your face after touching commonly touched items, like doorknobs or countertops.

      Usually, rhinoviruses don’t cause serious infections, but we’d all rather avoid getting colds. Vaccines haven’t been able to help us, though. There are three species (A, B, and C), which include about 160 known types. This means new types keep appearing. So far, scientists haven’t been able to come up with a vaccine that creates a response to all of these.

Knowing About Norovirus

      There’s one virus that everyone notices when it spreads. Norovirus spreads quickly in schools, hospitals, and cruise ships. It spreads mostly by fecal-oral transmission, meaning it spreads when tiny particles from one person’s stool (or vomit) get into someone else’s mouth. This can happen by direct contact with another person, when food or water is contaminated, or by touching surfaces that someone who is ill has touched. Norovirus can also be aerosolized, spreading in the air to people nearby. This can happen when we flush a toilet or vomit, sending tiny particles into the air that others swallow when they breathe.

      It doesn’t take much to infect us with norovirus. Our stool can contain billions and billions of virions, but it may take somewhere between ten to 100 of these to infect us. There can be asymptomatic spread.

Infection usually happens fast. We usually get sick 12–48 hours after exposure. Symptoms mostly include vomiting and diarrhea. This can lead to dehydration, along with muscle aches, headaches, and weakness. Usually there isn’t much of a fever — if anything there’s a low-grade fever. Most people get totally better in two to three days, but norovirus can be serious for folks with other illnesses or who are elderly and can’t tolerate the dehydration. A little under 1,000 people are thought to die from norovirus a year in the United States, mostly among the elderly, and over 100,000 need to be hospitalized.

      There isn’t a vaccine or a specific treatment for norovirus. Rehydration — often with Pedialyte or an oral rehydration serum and sometimes with IV fluids — is what gets us through the dehydration.

      Some people are immune to some types of norovirus thanks to a gene (FUT2) that they are born with. But this works against only some genotypes of norovirus. There are ten main groups and at least 48 different genotypes.

      Others develop immunity to specific types after getting sick, but not to all the genotypes, and it’s not clear how long this immunity lasts.

Understanding HIV

      Human immunodeficiency virus, or HIV, is responsible for more deaths than any other virus in recent history. Over 75 million people have been infected and about 33 million have died since the epidemic was first recognized. The first cases of AIDS (Acquired Immune Deficiency Syndrome) were identified in 1981, and the virus was identified in 1983.

      Because of fear of the virus, stigma, denial, and discrimination developed toward those who were infected, thought to be infected, or in high-risk groups. Many have worked to combat these issues.

      HIV can weaken the immune system and make us more prone to other infections we would otherwise fight off without ever getting sick. The virus attacks the immune system, and if not treated, it will go on to cause AIDS, where these opportunistic infections that we normally can fight off make us sick. About half of those with HIV develop AIDS in eight to ten years without treatment.

      It’s possible to have HIV without symptoms for many years. Some people have initial flu-like symptoms (fever, fatigue, rash, night sweats, muscle aches, sore throat, swollen lymph nodes) about two to four weeks after the initial infection. These symptoms can be overlooked because they seem like many other viruses (commonly mistaken for “mono” or Epstein-Barr virus, or EBV, in particular).

There’s no vaccine against HIV; however, there are many ways to reduce our chance of developing HIV. Safer sex, including using condoms when appropriate, has reduced sexual transmission risks. Using clean needles for any injection, including injection drugs, reduces transmission.

      There are also medications, called antiretrovirals, that can reduce transmission. Without treatment, 15 percent to 45 percent of mothers used to pass HIV onto their babies during pregnancy,