Name: St. Louis Encephalitis Virus (SLEV) [A.K.A. The ARBO from MO (read “the arBO from ehmO;” it sounds better that way, trust me.)]
Description: A member of the flaviviridae family, genus flavivirus, SLEV’s genome is comprised of nonsegmented, single-stranded, positive polarity linear RNA. Therefore, its genome alone is infectious. SLEV as a lipid-containing envelope and its capsid is icosahedral. It contains surface projection proteins (7 nm in diameter) which are antigenic and which exhibit hemagglutinin activity. Transcription occurs in the cytoplasm and is initiated via removal of a 5’cap. The 3’ end of SLEV’s mRNA is not polyadenylated. Its genome contains one open reading frame (ORF) and encodes 3 sturctural proteins (M, E, and C) and 7 non-structural proteins (polymerase and helicase). Mature viruses can be found hanging around the cytoplasm of nervous system, brain tissue, or liver cells.
Power: THIS VIRUS WILL MESS YOU UP! Infection with SLEV adversely affects the gastrointestinal system, nervous system, dermis, mucosa, or epithelium. Patients usually present with headache, photophobia, pyrexia, stiff neck, and/or uncoordination. Additionally, patients may develop hepatitis, liver dysfunction, meningitis, seizures, and (obviously) encephalitis. Lesions may occur in nerve, liver, or brain tissue. Outbreaks tend to occur during the summer months in the Midwestern, western, and southwestern U.S. SLEV is responsible for 10-40 cases of encephalitis annually in the U.S.

Offenses:
Attacks: SLEV is an arthropod-borne (ARBO) virus. It is transmitted primarily
by four main species of mosquito: Culex pipiens, Culex tarsalis, Culex quinquefasciatus, and Culex nigripalpus. Small wild birds (particularly English sparrows) act as a reservoir for this virus. Luckily, SLEV is not transmitted from person to person and infection is often subclinical.
Outcome: BLEAK. Encephalitis caused by SLEV has a 10% fatality rate (higher in elderly individuals). This virus means business.
Speed: Once a human is infected with the virus, the incubation period lasts anywhere from 4-21 days before symptoms occur. Fatal cases cause death within 7-14 days.

Defenses:
Vaccines: None available.
Behavioral: Bedrest is recommended. Preventable by avoiding contact with mosquito vectors (very difficult in summer).
Treatment: No antivirals available. Primarily supportive care: management of seizures and other neurological symptoms.

Game action: Miss 2 turns due to rest in bed. If you are over 60 years old, you may want to forfeit.
One liner: “Is that a mosquito on your SLEV?” “Oh shirt!”

Name: Western Equine Encephalitis Virus (WEEV), A.K.A. “The Horse Whisperer.”
Description: WEEV is a member of the togaviridae family, genus alphavirus. Its genome consists of nonsegmented, single-stranded, positive polarity linear RNA. Its envelope has distinctive surface projections and it surrounds a capsid with icosahedral symmetry (T = 4). Virions appear spherical and are 70 nm in diameter. Viruses enter the host cell by binding to receptors on the cell membrane. Replication of the virus occurs in the gut of the insect host and virions proceed to the salivary glands. Once transmitted to a human host, the virus continues to replicate. The mRNA contains both a 5’ cap and a 3’ polyadenylated tail.
Power: Symptoms of infection range from a mild flu-like illness to encephalitis, coma and death. Patients may experience any of the following: headache, malaise, photophobia, prostration, pyrexia, retardation, stiff neck, tremor, and/or uncoordination. Signs include meningitis, paralysis, seizures, and encephalitis (really?). Infection may also result in lesions in nerve tissue.

Offenses:
Attacks: WEEV is an ARBO virus transmitted primarily by Culicinae and Culex mosquitoes (vector) (Culex tarsalis plays a particularly important role in transmission to humans). It can be transmitted among wild birds (reservoir), but transmission to humans and horses (dead end hosts) must occur via the arthropod vector. WEV is not transmitted from person to person.
Outcome: Infection is often subclinical, with inapparent infections outnumbering apparent by an estimated 100:1. Brain damage occurs in 12-14% of infections (though, in almost 33% of infected infants) and infection is fatal in 2-3% of the people who develop severe clinical symptoms.
Speed: Symptoms occur within 5-10 days after receiving the arthropod bite and progress quickly in serious cases. In fatal cases, death can occur within 1-2 days of initial symptoms.

Defenses:
Vaccines: Vaccine available only for horses. No human vaccine.
Behavioral: Maintain respiration and nutrition in comatose patients.
Treatment: No antivirals available. Treatment of symptoms with antipyretics, analgesics, and anticonvulsants.

Game action: Debilitates horses of horse-riding players; 1 out of every 100 attacks causes severe damage and loss of $21,000-$3,000,000 (CDC’s reported range for total cost per case)!
One liner: “I think I may have WEEV.” “What are you ‘eq-whining’ about? That sounds fun!”

Name: Parainfluenza type 4 (PIV-4), A.K.A. “The Baby of the Family,” A.K.A. “The Insecure Virus.”
Description: PIV4 is a member of the paramyxoviridae family, genus paramyxovirus. Its genome consists of nonsegmented, single-stranded, negative polarity linear RNA. Paramyxoviruses, in general, are relatively large (particle size = 150-300 nm). PIV-4’s nucleocapsid has helical symmetry and its envelope consisting of a lipid bilayer taken from the host cell and virus glycoproteins HN and F. Transcription begins with a viral RNA-dependent RNA polymerase synthesizing a full-length mRNA which serves as a template for protein synthesis and for transcription of more negative sense RNA. Mature virions exit the cell via budding. Like viruses in the orthomyxoviridae family, PIV4 – and other paramyxoviruses – attach to sialic acid receptors on host cells as the first step in infection. The envelope then fuses with the host cell membrane; at this point, the virus uncoats and the nucleocapsid enters the cytoplasm.
Power: Don’t let PIV-4’s large size fool you: it’s a relatively weak virus. PIV-4 infection is usually asymptomatic, though it may result in mild upper-respiratory infections and/or fever (especially in younger children). In clinical cases, low-grade fever and coryza are the most common results of infection. Patients may complain of nasal congestion, sneezing, sore throat. PIV-4 is a much less common etiological agent than PIV-1 and PIV-2 which often cause croup and PIV-3 which often causes bronchiolitis and pneumonia. More severe infections due to PIV-4 tend to occur only in immunocompromised individuals.

Offenses:
Attacks: Infections are common, though associated clinical illnesses are much less frequent. Transmission occurs via direct contact with infected people, aerosols of respiratory secretions (coughing or sneezing), and fomites. Viral particles can their retain infectious potential on surfaces for up to 10 hours.
Outcome: You’ll be okay. PIV-4 may keep you in bed with a respiratory infection for a couple days, but infection is pretty mild and usually asymptomatic. Additionally, you’ve probably had your primary infection from PIV-4 before you were even 5 years old, and re-infections are much less severe clinically. Bronciolitis and viral pneumonia in infected children are extremely rare.
Speed: PIV-4’s incubation period is 2-6 days.

Defenses:
Vaccines: There is no PIV-4 vaccine used in clinical practice.
Behavioral:Bedrest is recommended. Since asymptomatic shedding is common, it is very difficult to prevent spread of infection, though washing hands and potentially contaminated surfaces may limit spread. These preventative measures are particularly important in avoiding nosocomial spread, as PIV-4-infected health care workers may show no symptoms, but may still spread the virus to an immunocompromised patient who will have a more clinically severe infection.
Treatment: Treatment of symptoms: Antipyretics can be used to control fever; Corticosteroids and nebulizers may be used to treat more severe respiratory syndromes. The antiviral RIbavirin has been shown to be effective against PIV-3 infection in vitro, but its effect on PIV-4 infection is not well studied.

Game action: If you get hit with this virus, I wouldn’t worry about it. Just keep playing.
Multi-liner: (A scene from virus gym class)
Team captain 1: I’ll take PIV-1, he’s good at causing croup.
Team captain 2: I get PIV-3, she’s a good etiological agent for bronchiolitis.
Team captain 1: (looks around…sees only PIV-4 is left…shrugs shoulders) Alright, I guess I’ll take PIV-4. But, you better cause some real symptoms this time!
PIV-4: (turning red) Aww, shucks! I can’t do anything right!