Diagnostics & Imaging Week Contributing Writer
SINGAPORE – Sophisticated point-of-care tests are becoming important factors in the Asian in vitro diagnostics market, as discussed at the inaugural Diagnostics Asia 2006 conference, organized by IBC Asia Pte Ltd. (Singapore) and held here in mid-January.
William Cao of NeuPro Technology Co. Ltd. (Taipei, Taiwan) described a new POC test system based on the company's NeuChip sensor, a low-cost biosensor that is being developed for time-critical diagnostic testing applications such as cardiac testing, rapid pathogen identification, and food toxicology. The sensor is fabricated using screen-printed electrode technology, and features electrochemical techniques using enzyme labels to achieve high sensitivity and low cost.
The test system consists of a test cartridge and a reader that connects to a Personal Digital Assistant for data storage and analysis. Total test turnaround time is less than three minutes for cardiac marker tests now under development. A rate-sensing method is used in the analysis, minimizing background effects. Additional tests for infectious disease are in the pipeline. The company is interested in licensing the technology for diagnostic applications, and is searching for strategic partners.
Another company focusing on point-of-care testing for infectious agents, the Foundation for Innovative New Diagnostics (FIND; Geneva, Switzerland), is developing new POC tests for tuberculosis with funding from the World Health Organization (WHO; also Geneva). FIND is a non-profit company founded in 2003 and has been funded through a $30 million initial investment by WHO as a spin-off from that organization. FIND is focused on the public health sector, with a goal of helping to reduce deaths due to infectious disease, which accounts for 45% of all deaths in Asia.
As discussed at the conference by Giorgio Roscigno, CEO of FIND, the initial focus of development efforts is on TB and malaria diagnosis. Existing TB test methods have a low diagnostic yield, with only 19% of all incident TB cases detected and reported as smear-positive in spite of the fact that over $1.2 billion is spent annually on TB diagnostic tests, as shown in the accompanying table.
Worldwide, 8.7 million new cases of TB occur annually, mostly in East Asia and Africa. One new test that is being developed by Proteome Sytems (North Ryde, Australia) is the DiagnostiQ antigen-based assay for use in developing countries. The test is designed to detect a panel of 62 proteins that are expressed in patients with TB infection. The target patient population for the test is the 16 million patients worldwide who are co-infected with HIV and TB. The test uses sputum, blood or plasma samples to detect active TB infections and has an analytical sensitivity of 100 pg/mL. Diagnostic sensitivity, however, for detection of TB infection is only 70%, and efforts are under way to improve sensitivity prior to launching the test. Jenny Harry, PhD, of Proteome Systems, who discussed the new TB test at the conference, said a prototype test is to be available by December of this year.
FIND also is also evaluating low-cost nucleic acid amplification technology for TB testing, and is working in partnership with BD (Franklin Lakes, New Jersey) to introduce rapid blood culture testing in Asia using the BD BBL MGIT system, which allows a reduction in turnaround time from 45 days to 14 days. Another TB test under evaluation by FIND uses phage technology combined with nucleic acid amplification for three- to four-day direct (non-culture) detection of TB in sputum.
FIND also is targeting development of improved diagnostic tests for malaria, a disease affecting 40% of the global population with a prevalence of 300 million cases, mostly in Africa, Southeast Asia and India, and the northern countries in South America. Although microscopy is the standard method used in malaria diagnosis, it is highly user-dependent and requires skilled personnel in order to obtain reliable results. There is an increased demand for accurate remote diagnostic malaria tests that can be used by non-skilled personnel.
As discussed at the conference by Dr. Mark Fukuda, chief of the department of immunology & medicine at the Armed Forces Research Institute of Medical Sciences (Bangkok, Thailand), dipstick tests for malaria-specific antigens are available at prices ranging from 60 cents to $2.50 (vs. a cost of 12 cents to 40 cents for microscopy), but such tests cannot differentiate lethal vs. non-lethal forms of the parasite that causes malaria. A new immunochromatographic test developed by Binax (Scarborough, Maine), the Malaria P.f./P.v. NOW ICT, provides subtyping of the parasite using a fingerstick blood sample. The test takes 20 minutes to perform, and the required skill level is low. However, sensitivity is considerably less than microscopy at over 100 parasites per microliter vs. 50 for microscopy.
Nucleic acid amplification tests for malaria have been developed for research use, and look promising, since sensitivity is less than 5 parasites per microliter and all subspecies can be detected, but at present such tests are research tools, not clinical products. Real-time PCR tests have been evaluated by Fukuda that appear promising, and that can potentially allow therapy to be monitored. However, he said he believes that antigen capture or immunochromatographic methods will prove to be the best methods for future malaria diagnostic testing.
Other important infectious disease testing applications in Asia include detection of Dengue infection and tracking transmission of Avian flu viruses (HN51). As discussed by Dr. Bijan Kumar Sil of the National Environment Agency, Environmental Health Institute (Singapore), a number of tests for dengue virus have been developed by his laboratory that use monoclonal-based competitive ELISA, real-time PCR or antigen ELISA to detect dengue infections at various stages of the disease, improving the ability of public health agencies to monitor infection outbreaks without the need for cell culture facilities.
Dr. Sze-Wee Tan, CEO of Rockeby Biomed Ltd. (Singapore), described a new rapid test for Avian flu that was introduced by his company last November. Rockeby has developed additional tests for vaginal infection in partnership with Pacific Biotech (Thailand). The existing Avian flu test is designed for testing of birds, and has been used in Southeast Asia, the Middle East, Eastern Europe and Japan. A human test also has been developed. The market for a human test, however, is very small due to the fact that only a few cases have so far been diagnosed. That situation could change if the virus mutates and begins to generate a human pandemic.