Influenza Virus

Infectious Agent: 

NAME: Influenza virus
SYNONYM OR CROSS REFERENCE: Flu; orthomyxovirus; influenza virus types A, B, and C
CHARACTERISTICS: Orthomyxoviridae; single-stranded negative sense RNA virus, segmented, mostly spherical 80-120 nm diameter, enveloped, highly pleiomorphic; strains of influenza A are described by geographic origin, strain number, year of isolation and hemagglutinin (H) and neuraminidase (N) antigens

Health Hazard: 

PATHOGENICITY: An acute viral disease of the upper respiratory tract characterized by acute fever, chills, headache, myalgia, weakness, runny nose and mild sore throat and cough, cough can be severe; nausea and vomiting are uncommon; fatality is generally low, except in those with chronic lung or heart conditions; recovery in 2-14 days
EPIDEMIOLOGY: Influenza can occur in pandemics and epidemics, localized outbreaks, and as sporadic cases; type A includes 3 subtypes (H1N1, H2N2, H3N2) associated with widespread epidemics and pandemics, epidemics of influenza A have appeared in North America at intervals of roughly 1-3 years, influenza B every 3-4 yrs; mixed epidemics also occur; type C has been associated with sporadic cases and minor localized outbreaks, but has never been associated with epidemic outbreaks; disease more severe in older persons, children and persons with cardiac or pulmonary conditions or immune compromised individuals,
HOST RANGE: Influenza A virus - humans; swine, horses; domestic and wild avian species, influenza B virus - humans only
INFECTIOUS DOSE: Influenza A 2-790 p.f. units (nasopharyngeal route)
MODE OF TRANSMISSION: By direct contact through droplet infection, aerosols; airborne spread among crowded populations in enclosed spaces; virus may persist for hours in dried mucus and be transmitted by direct contact (occasionally fomites)
INCUBATION PERIOD: Short, usually 1-4 days
COMMUNICABILITY: Highly communicable; probably limited to 3-5 days from clinical onset, up to 7 days in young children


RESERVOIR: Humans; animal reservoirs (particularly swine) are suspected assources of new human subtypes
ZOONOSIS: Yes, transmission from animal to man has been demonstrated on only very rare occasions; influenza virus transmission have been reported to occur between swine, humans and wild and domestic fowl


DRUG SUSCEPTIBILITY: Type A is usually susceptible (other types are resistant) to amantadine HC1 and rimantadine HCL (given with in first 48 hrs of the disease in adults), no affect on influenza type B; trial studies on two new drugs (Relenza and Tamiflu - neuramidase inhibitors) appear to be extremely effective
SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to disinfectants - 1% sodium hypochlorite, 70% ethanol, glutaraldehyde, formaldehyde
PHYSICAL INACTIVATION: Susceptible to heat (56° C for at least 30 min) and radiation
SURVIVAL OUTSIDE HOST: Dried mucus - several hours, virus particles are relatively labile


SURVEILLANCE: Monitor for symptoms of flu
FIRST AID/TREATMENT: Fluids and rest; amantadine or rimantadine HC1 useful in prevention and attenuation of influenza A infections; antibiotic treatment to prevent secondary bacterial pneumonia
IMMUNIZATION: Active immunization for serotypes A and B directed primarily at persons with greatest risk of serious complication or death (certain health care personnel); 70-80 % effective when sufficient mass of antigen closely matches the prevailing wild strain of virus; vaccine should be given each year before influenza season
PROPHYLAXIS: In epidemic situation, amantadine or rimantadine HCl usefulfor influenza A, not influenza type B; new inhibitors of influenza neuraminidase (oseltamivir) particularly effective against influenza A and B

Laboratory Hazards: 

LABORATORY-ACQUIRED INFECTIONS: Not normally documented in literature, but are known to occur by informal accounts and published reports, particularly when new strains showing antigenic drift or shift are introduced into the laboratory; 15 reported cases up to 1974; animal-associated infections are not reported, however, risk is high from infected ferrets
SOURCES/SPECIMENS: Respiratory tissues or secretions of humans or most infected animals; cloaca of many infected avian species; virus may be disseminated in multiple organs in some infected animal species
PRIMARY HAZARDS: Inhalation of virus from aerosols generated when aspirating, dispensing, or mixing virus-infected samples; from infected animals, especially ferrets
SPECIAL HAZARDS: Genetic manipulation of virus has unknown potential for altering host range, pathogenicity or for introducing into man transmissible viruses with novel antigenic composition

Handling Information: 

SPILLS: Allow aerosols to settle; wearing protective clothing, gently cover spill with absorbent paper towel and apply 1% sodium hypochlorite, starting at perimeter and working towards the centre; allow sufficient contact time (30 min)
DISPOSAL: Decontaminate before disposal; steam sterilization, chemical disinfection, incineration
STORAGE: In sealed containers that are appropriately labelled

Miscellaneous Information: 

Date prepared: Created in December 2010-  largely modified from protocols derived from the NIH, the Public Health Agency of Canada, and other related literature. 
Prepared by: Michael McManus, PhD, UCSF
Although the information, opinions and recommendations contained in this Material Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.