Chimpanzees do not appear to become ill from dengue infection. As with many other viral diseases which afflict humans, chimpanzees can harbor the virus, but it does not cause a similar illness in them. (1) As such, “Doctors [still] have no specific drugs to treat dengue fever,” despite years of subjecting chimpanzees to its research. (2)
Dengue (pronounced deng - ay) fever is a viral disease that is endemic to tropical and sub-tropical areas. It is transmitted by mosquitoes that carry any one of four viral strains for the disease. (3) Dengue fever used to be called “break-bone fever” because it can cause severe joint and muscle pain. Other symptoms include an extremely high fever, severe headache, rash, pain behind the eyes, nausea, and vomiting. According to the National Institute of Allergy and Infectious Diseases (NIAID), “there is no specific treatment for classic dengue fever” and with minimal treatment—bed rest, fluids, and non-aspirin pain relievers—“most people recover within 2 weeks.” (4)
Research using chimpanzees
One of the leading researchers in dengue fever for NIAID is Dr. Ching-Juh Lai. Dr. Lai’s “goal is to define the mechanisms that allow the virus to reproduce, or replicate, using cultured cells and animal models.” (5) From 2000 to 2008, Dr. Lai has been using chimpanzees in dengue research under grant 1Z01AI000682 from the National Institutes of Health (NIH). (6)
Under the grant’s title of “Recovery of Chimpanzee Dengue Virus Neutralizing Antibody” in 2002, Dr. Lai’s research required chimpanzees to undergo intrahepatic inoculation [inoculation directly into the liver] of the dengue virus followed by regular blood-draws and also several bone marrow biopsies. (7) The chimpanzees used in this research were housed at BIOQUAL, Inc., a private laboratory in Rockville, Maryland; we do not know if the same situation applies to his current research. On their website, NIAID states that, “Much of the basic research on dengue fever is done in labs at NIAID,” which are located in Bethesda, Maryland. (8)
Continuing his research in 2008 under the grant title of “Humanized Antibodies Derived from Chimpanzee Fabs that Neutralize Flaviviruses,” Dr. Lai now uses “monoclonal antibodies (MAbs) from chimpanzees infected with multiple dengue virus serotypes.” (9) In addition to dengue fever research, this study also mentions using chimpanzees for Japanese encephalitis virus (JEV) research.
Currently, “NIAID is funding nearly 60 dengue research projects, including studies on dengue hemorrhagic fever and dengue shock syndrome, the most severe forms of the disease.” (10) In April 2009, NIAID announced they had promising results from one recent study that focused on the two organisms involved in spreading the virus, mosquitoes and humans:
“Now, researchers have identified cellular components in mosquitoes and in humans that dengue virus uses to multiply inside these hosts after infecting them. Their findings could lead to the development of anti-dengue drugs that would inhibit one or more of these host factors, thus curtailing infection and the development of disease.” (11)
(1) Harrison VR, Eckels KH, et al. 1977 Virulence and immunogenicity of a temperature-sensitive dengue-2 virus in lower primates. Infect Immun. Oct;18(1):151-6.
(2) “New Understanding of Dengue Virus Points Way to Possible Therapies for Dengue Fever.” NIAID News Release, Wednesday, April 22, 2009.
(3) How Dengue Virus Matures and Becomes Infectious. NIAID Dengue Fever Fact Sheet, February 19, 2009.
(5) Dengue Research in NIAID Labs. NIAID Dengue Fever Fact Sheet, March 18, 2009.
(6) Computer Retrieval of Information on Scientific Projects (CRISP) database
(7) Men R, Yamashiro T, et al. 2004 Identification of chimpanzee Fab fragments by repertoire cloning and production of a full-length humanized immunoglobulin G1 antibody that is highly efficient for neutralization of dengue type 4 virus. J Virol May;78(9):4665-74.
(9) CRISP database