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RESEARCH MODELS AND SERVICES

Filovirus (FV)ClassificationSingle-stranded, negative-sense RNA, enveloped

Family Filoviridae

Affected SpeciesNonhuman primates (NHPs) (chimpanzee, monkey,

macaque, orangutan, and baboon) and humans

FrequencyThe risk of NHPs in commercial primate colonies becoming

infected with filovirus is extremely low. However, filoviruses

are zoonotic and transmissible to humans from infected

NHPs, and therefore require routine screening during

quarantine while importing animals.

TransmissionMembers of the filovirus family are Marburgvirus and

Ebolavirus, named after their sites of outbreak. The first

filovirus outbreak with Marburgvirus occurred in 1967 in

Germany and Yugoslavia, when laboratory technicians

handling tissues from African green monkeys developed

hemorrhagic fever. Ebolavirus was first identified in 1976

when two outbreaks of Ebola occurred in northern Zaire

and southern Sudan. Five species of Ebolavirus have been

identified to date: Zaire, Sudan, Bundibugyo, Taï Forest

(formerly Ivory Coast), and Reston, Virginia, USA. In 1989,

filovirus was introduced into a NHP colony in Reston from

animals originating from the Philippines. Ebola-Reston is the

only known filovirus that does not cause severe disease in

humans; however, it can still be fatal in monkeys.

The virus is transmitted to people from wild animals and

spreads in the human population through human-to-

human transmission. The exact transmission mode from

the natural virus reservoir to a host (nonhuman primate)

is unknown. However, animal-to-person and person-to-

person transmission occurs via direct contact of infected

bodily fluids or contaminated materials. Two laboratory

experiments have demonstrated the viruses have limited

infectivity through small-particle aerosols. Airborne spread

among humans has not been clearly demonstrated.

SummaryFilovirus is transmitted to

humans or monkeys through wild

animals and by direct contact

of infected bodily fluids from

human to human. Hemorrhagic

fever, organ failure and internal/

external bleeding are the clinical

signs in humans and nonhuman

primates. The most common

method for screening for filovirus

in nonhuman primate colonies is

by MFIA or ELISA using serum for

detection of infected antibodies.

askcharlesriver@criver.com • www.criver.com © 2018, Charles River Laboratories International, Inc.

Clinical SignsFilovirus can cause severe hemorrhagic fever in both

humans and nonhuman primates. The time frame from

infection to onset of symptoms is 2 to 21 days. Initial

symptoms in humans are sudden onset of fever, fatigue,

muscle pain, headache, and sore throat. This is followed by

vomiting, diarrhea, rash, symptoms of impaired kidney and

liver function, and in some cases, both internal and external

bleeding. Laboratory findings include low white blood cell

and platelet counts and elevated liver enzymes.

DiagnosisFilovirus causes an acute, serious illness which is often

fatal in both humans and NHPs. The historic mortality rate

in human ranges from 25% to 90%. There is currently

no licensed vaccine for filovirus, although several are in

development due to recent human outbreaks in Africa in

year 2015-16. Multiple assays are used to confirm filovirus

infections: antibody or antigen capture ELISA, serum

neutralization, RT-PCR, EM, and in vitro virus isolation.

Early medical intervention is critical in improving chances

of survival. Test results should be scrutinized, taking into

consideration filovirus disease prevalence in the local

general population.

Interference with Research

Due to the high mortality rate of filovirus-infected animals,

its interference with NHP studies is not a factor.

Prevention and TreatmentIn the event of an outbreak, infected NHPs and humans

should be isolated, and follow the viral hemorrhagic fever

isolation precautions initiated per CDC guidelines.

References https://www.cdc.gov/vhf/virus-families/filoviridae.html

http://www.who.int/mediacentre/factsheets/fs103/en/

Serologic Cross-Reactivity of Human IgM and IgG

Antibodies to Five Species of Ebola Virus, Adam MacNeil,

Zachary Reed, Pierre E. Rollin, Viral Special Pathogens

Branch, The Centers for Disease Control and Prevention,

Atlanta, Georgia, United States of America.

Preliminary report: isolation of Ebola virus from monkeys

imported to USA, Jahrling PB, Geisbert TW, Dalgard DW,

Johnson ED, Ksiazek TG, Hall WC, Peters CJ, Lancet.

1990 Mar 3;335(8688):502-5.

Ebola virus disease and the veterinary perspective,

Ann Clin Microbiol Antimicrob. Semra Gumusova,

Mustafa Sunbul, and Hakan Leblebicioglu, PMCID:

PMC4450609, 2015; 14: 30, Published online

2015 May 28. doi: 10.1186/s12941-015-0089-x.