Speeding up cholera diagnosis
14 Oct 2011 by Evoluted New Media
Laboratory News learns how the latest molecular diagnostics technology is helping to manage the cholera crisis in Haiti
A recent study published in the Lancet predicts that there may be as many as 779,000 cases of cholera and 11,000 fatalities in Haiti this year – an astounding number1. The spread of the disease is moving quickly in the country, and medical professionals are doing what they can to more quickly and effectively diagnose and treat cases in order to slow its spread. Reports from the World Health Organisation (WHO) indicate that the Haiti Alert and Response system have detected increased reports of cholera compared to previous averages – in June 2011, Ministry of Health (MSPP) reported 363,117 cases since the beginning of the outbreak, including 5,506 deaths2.
Since the January 2010 earthquake and the beginning of the cholera outbreak in mid-October, the Haitian Group for the Study of Kaposi’s Sarcoma and Opportunistic Infections (GHESKIO) in Port-Au-Prince has been providing humanitarian assistance and emergency care to those affected by the disaster.
The GHESKIO Centre, the first institution in the world dedicated to the fight against HIV/AIDS, has provided continuous medical care in Haiti since 1982 – never once shutting its doors or charging fees.
In the early 1980s, a group of Haitian clinicians noticed a growing number of patients dying from Kaposi’s sarcoma and unusual opportunistic infections. In 1982, they founded the Haitian Group for the Study of Kaposi’s Sarcoma and Opportunistic Infections (GHESKIO). A year later, GHESKIO published their experiences in The New England Journal of Medicine, documenting the first cases of AIDS in a developing country.
GHESKIO was recognised as an official independent non-governmental organisation by the Haitian Government in 1987, and in 2000, the Haitian government designated GHESKIO a “Public Utility,” a status reserved for institutions “essential to the welfare of the Haitian people” such as the Red Cross. For more than twenty years, GHESKIO has served as the Haitian Government’s research and training centre for HIV/AIDS and it is now an internationally recognised centre of excellence.
Members of the GHESKIO Institute of Infectious Diseases and Reproductive Health (IMIS) laboratory recently received training on two of the most recent advances in GI diagnostics, the Luminex MAGPIX multiplexing system and the recently CE mark approved xTAG Gastrointestinal Pathogen Panel (GPP) to help in speeding the diagnosis and stemming the spread of cholera in Haiti.
MAGPIX is a versatile and flexible multiplexing bioassay platform based on Luminex's xMAP Technology that can be used to analyse both nucleic acids and proteins, making it applicable in many clinical and research laboratory settings. The system can simultaneously perform up to 50 tests in a single reaction volume, greatly reducing the amount of required sample, reagents and labour over competing systems while improving productivity, and is capable of running a 96-well plate and producing 4800 data points in approximately one hour.
Unlike flow cytometry based multiplexing systems which employ lasers, the MAGPIX System uses LED’s and a CCD imaging sensor. Equivalent assay performance from these lower cost components is facilitated by the magnetic capture of microspheres within the system. The ability to reduce space, cost, calibration, and labour requirements while providing rapid, highly sensitive and accurate results is a significant advantage for laboratories like GHESKIO’s IMIS. The system, weighing less than 40 pounds, (approximately 18 kg), requiring relatively little valuable laboratory bench top space and being easy to install, was set up and functional by the technicians in less than two hours. After brief training of the IMIS staff and validation of the system, the IMIS team was generating results within five hours for cholera and 14 of the other most common causative pathogens for infectious gastroenteritis using the recently CE mark approved xTAG Gastrointestinal Pathogen Panel (GPP).
The xTAG GPP is a polymerase chain reaction-based (RT-PCR) molecular test that enables multiple analyses for nucleic acids from three pathogen types – bacterial, viral, and parasitic – in a single reaction well. It is the first test that can identify up to 95% of the disease causing pathogens for gastrointestinal infections in a single test, delivering the highest number of relevant answers per sample in less than five hours. Achieving differential diagnosis of infectious gastroenteritis traditionally requires multiple tests that are run over the course of several days. Ability to simultaneously test for multiple causative agents is important for the GHESKIO IMIS staff since it allows infected patients to be quickly triaged and appropriately managed. Positive cholera patients can receive immediate treatment, helping to prevent the growing number of deaths and further spread of the disease. Additionally, patients who are infected with other pathogens or multiple pathogens (such as cholera and/or shigella or salmonella) can be quickly identified and receive appropriate care.
“We think the Luminex assay will significantly change the way we look at the causes of infectious diarrhoea in Haiti,” said Macarthur Charles, GHESKIO IMIS Director, and Associate Professor of Medicine Weill Cornell Medical College. “In addition, it will allow us to better predict and react to outbreaks of acute diarrhoeal illness in Haiti.”
Currently GHESKIO-IMIS is evaluating the development of other custom assays that would be useful, including TB, malaria and dengue fever.
References:
- Andrews JR, Basu S. “Transmission dynamics and control of cholera in Haiti: and epidemic model”, Lancet. 2011 Apr 9;377(9773):1248-55. Epub 2011 Mar 15
- World Health Organization Regional Office, Pan American Health Organization (PHAO), EOC Situation Report “Cholera Outbreak in Haiti” Cholera Hispaniola - PAHO EOC Sit Rep 20 (July 1 2011)
