FDA Permits Marketing of First Test to Help Diagnose Dengue Fever

/PRNewswire/ -- The U.S. Food and Drug Administration today allowed marketing of the first test to help diagnose people with signs and symptoms of dengue fever or dengue hemorrhagic fever, a leading cause of illness and death in the tropics and subtropics.

The dengue virus is transmitted to humans by the bite of an infected Aedes mosquito. As many as 100 million people worldwide are infected by the virus each year, according to the U.S. Centers for Disease Control and Prevention (CDC).

Symptoms of dengue fever include high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash and mild bleeding involving the nose or gums, and easy bruising.

Most reported dengue cases in the continental United States occur in people returning from travels to tourist destinations in Latin America, the Caribbean and Southeast Asia. Dengue is also endemic in the U.S. in Puerto Rico, the Virgin Islands and some U.S.-affiliated Pacific Islands. Recently, dengue outbreaks have occurred in Hawaii, Texas, and Florida.

The DENV Detect IgM Capture ELISA test detects antibodies to dengue virus in blood samples from patients who have signs and symptoms of dengue. The test will be available for use in clinical laboratories and will assist in the diagnosis of dengue, which can improve patient care and management.

The DENV Detect IgM Capture ELISA test is based on technology patented by the CDC and manufactured by Seattle-based Inbios Inc.

"Cases of dengue fever or dengue hemorrhagic fever can be potentially fatal for people who do not recognize the symptoms," said Alberto Gutierrez, Ph.D., director of the Office of In Vitro Diagnostics Device Evaluation and Safety in FDA's Center for Devices and Radiological Health. "This test will now aid health care professionals in their effort to more effectively diagnose dengue."

The FDA reviewed data for the test via the "de novo" pathway, an alternative path to market for devices that are low to moderate risk and may not require premarket approval (PMA), but are of a new type, and therefore may not be able to be cleared in a "510(k)" premarket notification.

People who believe they have dengue should immediately contact a health care professional. There are no FDA-licensed vaccines to prevent dengue and no medicines specifically approved to treat the infection.

The test should not be used in people who do not show signs or symptoms of dengue. Diagnostic testing for dengue is complicated by the fact that an IgM antibody response to the dengue virus infection is not detectable until 3-5 days after the onset of fever, which can produce a negative test result even though a person has dengue. During this "IgM negative window" the dengue virus is present in the bloodstream.

There are currently no FDA-cleared or approved tests for direct detection of dengue virus.

This new test shows cross-reaction with other closely related viruses such as those that cause West Nile disease. However, in most patient testing situations found in the United States, a positive test result in a patient with signs or symptoms consistent with dengue should be considered presumptive evidence of dengue.

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Researcher uses federal grant to investigate West Nile Virus

Georgia State University’s Margo Brinton, a Regents’ Professor in the Department of Biology, received a $289,000 federal stimulus grant from the National Institutes of Health to continue her research on West Nile virus, which is transmitted to humans by mosquitoes.

West Nile virus causes either a mild illness characterized by short-term flu-like symptoms or no symptoms at all in most people it infects. But for some, infection results in severe illness, with the possibility of permanent neurological effects or death, according to the Centers for Disease Control and Prevention.

Specifically, this grant will focus on studies aimed at understanding how West Nile virus manipulates and commandeers cell proteins and processes to enhance its own replication.

“By gaining a detailed understanding these complicated interactions, we’re defining new targets for the development of antiviral therapies, and we’re also learning more about cell functions,” Brinton said.

Another of the projects ongoing in Brinton’s lab is focused on understanding why a small number of people infected with West Nile virus become extremely ill, even though they have normal responses to infections with other types of viruses. This work may lead to the development of a way to identify individuals who are highly susceptible to West Nile virus. These would be good candidates for vaccination with a “killed” vaccine but not a “live” one for this virus.

The idea that genetic factors could control the severity of the disease developed by individual humans after infection with West Nile virus is based in part on work done by Brinton’s lab on mice. In mice, a single, dominant gene determines whether a mouse lives or dies after a West Nile infection. Although the general location of this gene in the mouse DNA genome had been determined, the identity of the gene was not known until 2002, when Brinton’s lab compared a region of 650,000 DNA base pairs in resistant and susceptible mice and found the single change between them that made the difference.

Brinton, who first came to Georgia State in 1989, has been working on West Nile virus since the 1960s. “In the 1960s, West Nile virus was circulating primarily in Africa and the Middle East and was thought to cause only mild disease symptoms in humans,” Brinton said. One group of physicians thought that this virus was safe enough to be used to help cancer patients by generating interferon – a cell proteins made and released in response to pathogens that can act against tumors.

However, the patients – who already had weakened immune systems due to their cancer – died. Because of these human deaths, West Nile virus received a higher safety-level classification, meaning that scientists had to take more precautions when working with it. Additionally, the strain of virus that came to the United States in 1999 is more virulent than previously known strains.

Even though Brinton’s lab primarily works with less virulent strains of the virus, she and her staff take multiple precautions and work with live virus only in secure labs that are rated at Biosafety level 3, with level 4 being the highest safety rating.

For more information about West Nile virus, visit www.cdc.gov/ncidod/dvbid/westnile/index.htm.

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FDA Approves New Vaccine to Prevent Japanese Encephalitis

The U.S. Food and Drug Administration today approved IXIARO, a vaccine to prevent Japanese encephalitis (JE) which is caused by a mosquito-transmitted virus found mainly in Asia. IXIARO will be the only vaccine for JE available in the United States.

"This vaccine offers protection for individuals who travel to or live in areas where outbreaks are known to occur," said Karen Midthun, M.D., acting director of the FDA's Center for Biologics Evaluation and Research.

In Asia, JE affects about 30,000 to 50,000 people each year, resulting in 10,000 to 15,000 deaths. JE is rarely seen in the United States, with very few cases reported among civilians and military traveling from the United States to Asia.

The virus that causes JE affects membranes around the brain and mild infections can occur without apparent symptoms other than fever and headache. In people who develop severe disease, JE usually starts as a flu-like illness but can worsen, causing high fever, neck stiffness, brain damage, coma, or even death. The disease is transmitted via infected mosquitoes; it is not spread from human to human.

IXIARO is a second-generation JE vaccine,in that itis manufactured using cell culture technology leading to improved manufacturing efficiency as well as more reliable control of the vaccine manufacturing process. This technology utilizes an established bank of cells that can be drawn from at any time contributing to the assurance of consistent vaccine quality.It also enhances the ability to rapidly manufacture a vaccine on a large scale if needed, without compromise to the vaccine's safety or effectiveness.

Clinical studies were conducted in more than 800 healthy men and women in the United States and Europe. Participants received either IXIARO or JE-VAX, another U.S.-licensed vaccine that is no longer being manufactured. The studies found that IXIARO produced sufficient levels of antibodies in the blood to protect against JE. IXIARO requires two doses instead of JE-VAX's three.

The vaccine was well tolerated and the most commonly reported adverse events were headache, muscle pain and pain, swelling, and tenderness at the injection site. Overall, it was more tolerable and had fewer side effects than the comparator, JE-VAX.

IXIARO is manufactured by Intercell Biomedical, Livingston, U.K.

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