See also Coronaviruses (family Coronaviridae)

Cleaning Respiratory Equipement

Adenoviruses (see outline)

  Hantaviruses

Hantaviruses comprise an emerging global threat for public health, affecting about 30,000 humans annually. Infection may lead to Hantavirus pulmonary syndrome (HPS) in the Americas and hemorrhagic fever with renal syndrome (HFRS) in the Europe and Asia. Humans are spillover hosts, acquiring infection primarily through the inhalation of aerosolized excreta from infected rodents and insectivores. Risk factors for infection include involvement in outdoor activities, such as rural- and forest-related activities, peridomestic rodent presence, exposure to potentially infected dust and outdoor military training; prolonged, intimate contact with infected individuals promotes transmission of Andes virus, the only Hantavirus known to be transmitted from human-to-human.  See Watson

Structure: Hantaviruses are segmented, enveloped viruses which are associated with acute respiratory distress. The virus is an enveloped virus of the Bunyaviridae family. It is transmitted via airbone dust contaiminated with the urine, feces or saliva of infected rodents. Deer mice and other rodents can carry the virsu with few apparent symptoms.

Tramissission is by the deer mouse via dropping. Incidence increases in rainy years in SW US. This virus became of concern in the US in 1993 when a cluster of unusual cases of severe lung edema amoung healthy young adults arose in New Mexico. Most of the patients died within a few days. It became clear that the virus was associated with the presence of mice in close proximity to the victims. The disease has a mortality rate of at least 33%.

In 2012, hantavirsu caused a localized outbreak among visitors to Yosemite National Park. Visitors were staying in tent cabins and were exposed to mouse droppings containing the virus. Three people died and at least 10 were sickened. The tents were of a double walled design but the space between the walls turned out to be a perfect nesting space for the mice.

Etiology: Once the hantavirus enters the human body, it replicates and spreads. In the lungs, the virus causes blood vessels to become weak and leak, which fills air sacs with blood and makes breathing difficult. In the heart, damage to the heart muscle itself plus weak and leaky blood vessels reduce the heart’s ability to pump oxygen-filled blood to organs and cells of the body. Without oxygen and adequate blood pressure, the body can go into shock, which in turn can result in organ failure followed rapidly by death. See Cleveland Clinic

Detection: A positive serological test result, evidence of viral antigen in tissue by immunohistochemistry, or the presence of amplifiable viral RNA sequences in blood or tissue, with compatible history of HPS, is considered diagnostic for HPS. See CDC

Treatment: There is no specific treatment, cure, or vaccine for hantavirus infection. However, we do know that if infected individuals are recognized early and receive medical care in an intensive care unit, they may do better. In intensive care, patients are intubated and given oxygen therapy to help them through the period of severe respiratory distress. See CDC

Orthomyxoviruses

Orthomyxoviruses have a  segmented genome with an envelope. Groups include

(A, B, C). A&B are more severe (complications include pneumonia).  Incubation time is about 2 days. Major proteins include hemagglutinin (H), neurominidase (N) and matrix. Antibodies against H and N are protective to influenza (vacines are based on these proteins).

Types of Flu viruses:

There are four types of influenza viruses: A, B, C and D. Human influenza A and B viruses cause seasonal epidemics of disease (known as the flu season) almost every winter in the United States. Influenza A viruses are the only influenza viruses known to cause flu pandemics, i.e., global epidemics of flu disease. A pandemic can occur when a new and very different influenza A virus emerges that both infects people and has the ability to spread efficiently between people. Influenza type C infections generally cause mild illness and are not thought to cause human flu epidemics. Influenza D viruses primarily affect cattle and are not known to infect or cause illness in people.

Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N). There are 18 different hemagglutinin subtypes and 11 different neuraminidase subtypes (H1 through H18 and N1 through N11, respectively). While there are potentially 198 different influenza A subtype combinations, only 131 subtypes have been detected in nature. Current subtypes of influenza A viruses that routinely circulate in people include: A(H1N1) and A(H3N2). Influenza A subtypes can be further broken down into different genetic “clades” and “sub-clades.” See the “Influenza Viruses” graphic below for a visual depiction of these classifications.

See CDC

Treatment options for Influenza:

There are prescription medications called “antiviral drugs” that can be used to treat flu illness. CDC recommends prompt treatment for people who have flu infection or suspected flu infection and who are at high risk of serious flu complications, such as people with asthma, diabetes (including gestational diabetes), or heart disease. When treatment is started within two days of becoming sick with flu symptoms, antiviral drugs can lessen fever and flu symptoms and shorten the time you are sick by about one day. They also may reduce the risk of complications such as ear infections in children, respiratory complications requiring antibiotics, and hospitalization in adults.  For people at high risk of serious flu complications, early treatment with an antiviral drug can mean having milder illness instead of more severe illness that might require a hospital stay.  For adults hospitalized with flu illness, some studies have reported that early antiviral treatment can reduce their risk of death. The anti-viral drugs are the following:

• oseltamivir phosphate (available as a generic version or under the trade name Tamiflu®),
• zanamivir (trade name Relenza®)
• peramivir (trade name Rapivab®), and
• baloxavir marboxil (trade name Xofluza®) See CDC flu treatment

More on the Influenza viruses from the CDC

Paramyxoviruses

Paramyxoviruses have a genome and are enveloped. Serotypes include parainfluenza viruses which cause bronchiolitis and pneumonia in infants in the hospital setting such as the following:

Mumps contains both a fusion factor and a hemogluttin (HN) glycoprotein. Immunity is life long.

Nipah virus (NiV) was first discovered in 1999 following an outbreak of disease in pigs and people in Malaysia and Singapore. This outbreak resulted in nearly 300 human cases and more than 100 deaths, and caused substantial economic impact as more than 1 million pigs were killed to help control the outbreak. NiV is a member of the family Paramyxoviridae, genus Henipavirus. It is a zoonotic virus, meaning that it initially spreads between animals and people. The animal host reservoir for NiV is the fruit bat (genus Pteropus), also known as the flying fox. See CDC

Human Respiratory syncytial virus (RSV): 

–Introduction/Structure: RSV is a negative-sense, single-stranded RNA virus of the genus Pneumovirinae and the family Paramyxoviridae. It cause bronchiolitis and pneumonia particularly in infants and can also cause croup. RSV has no HN protein but it does have a Fn protein which causes syncytia. RSV belongs to the virus family Paramyxoviridae, genus Pneumovius. It is expected that up to 50% of infants will suffer from RSV infections during their first winter. Although RSV is common in the young, the virus is found in respiratory secretions of infection persons of any age.

RSV is the leading cause of hsptialization among infants in the Untied States. (Moline “early estimate of Nirsevimab effectiveness for prevention of respiratory syncytial virus – associated hospitalization among infants entering their first respiratory syncytial virus season – new vaccine surrveillance Network, October 2023-February 2024”, MMWR, March 7, 20024, 73(9))

RSV infections can become serious in elderly or immunocompromised adults aged 60 or more. On June 21, 2023, the Advisory Committee on Immunization Practices recommended that persons aged 60 and above may receive a single dose of RSV vaccine. In May 2023, the FDA approved the first two vaccines for prevention of RSV lower respiratoyr tract disease (LRTD) for use in adults aged 60 or more years. For both vaccine products, vaccination with a single RSV vaccine dose demonstrated moderate to high efficacy in preventing symptomatic RSV-associated LRTD among adults aged 60 or more. See CDC

RSV is easily spread by physical contact with contaminated secretions. The virus can survive for at least half an hour on hands and for hours on countertops and used tissues. Outbreaks amoung the elderly have been associated with serious and fatal illness.

–Vaccines:

FDA has required and approved safety labeling changes to the Prescribing Information for Abrysvo (Respiratory Syncytial Virus Vaccine) manufactured by Pfizer Inc. and Arexvy (Respiratory Syncytial Virus Vaccine, Adjuvanted) manufactured by GlaxoSmithKline Biologicals.

–ABRYSVO (Pfizer Inc.) is a vaccine indicated for active immunization for the prevention of lower respiratory tract disease (LRTD) caused by respiratory syncytial virus (RSV) in individuals >60.

–AREXVY: (GlaxoSmithKline Biologicals SA)

–Treatment:

Ribaviris is approved for treatment of RSV infection. However, clinical data has failed to support early promise of this antiviral agent and the American Academy of Pediatric suggests that use be restricted to only the most severe cases (US 2006/0115485).

Nirsevimab: In August 2023, CDC’s Advisory Committee on Immunization Practices (ACIP) recommended ninevimab, a long acting monoclonal antibody, for all infants aged <8 months born during or entering their first RSV season, and for children aged 8-19 months at increased risk for severe RSV disease and enteirng their second RSV season. In a pooled analysis of data from prelicensure randomized placebo-controlled clinical trails, 1 dose fo nirsevimab given at age <8 months was 79% efficacious against medcially attended RSV associated lower respiratory tract infection and 81% efficacious against RSV associated lower respiratory tract infection with hospitalization through 150 days after infection. Moline “early estimate of Nirsevimab effectiveness for prevention of respiratory syncytial virus – associated hospitalization among infants entering their first respiratory syncytial virus season – new vaccine surrveillance Network, October 2023-February 2024”, MMWR, March 7, 20024, 73(9))

Synagis (Medimmune, Inc) is an approved antibody for treating Respiratory Syncytial Virus infections in children.

Sendal:

Simian virus 5

–human metapneumovirus caues bronchiolitis and pneumonia, mainly in children under 2. 100% of people will be seropositive by 10.

Picornaviruses

Picornaviruses are  naked virion viruses. Members which cause respiratory distress include:

I. Enteroviruses are spread mainly by the fecal-oral route (as with contaminated swimming pools). They are easy to transmit and can last up to 4 months in feces. Symptoms range from mild to life threatening. Enteroviruses include the following:

coxsackieviruses such as Coxcakie B1 and Coxsacki B3

polioviruses (the incidence has declined worldwide due to the Salk and Sabine vacinnes (1955, 1963).

II. Cardio

Encephalomyocarditis

Rhabdoviridae

Rabies:

VSV:

rhinoviruses

There are more than 100 serotypes of rhinoviruses. Huamn rhinovirus (HRV) infection is one of the most fequent cuases of the common cold. In HRV infection, pathogen-specific immune respones are hindered in the respiratory tract, making patients susceptible to secondary bacterial infection and leading to bronchitis and pneumonia. This has been attributed to a functional cahnge in DCs, which dependent on and sialoadhesin.