- New Rapid Diagnostic Test for Worm Infection Provides Substantial Improvement Over Current Standard, According to New African Field Study; Provides Compass to Guide Public Health Efforts to Halt Debilitating Lymphatic Filariasis (Elephantiasis)
- Two Studies on Efforts to Eliminate Onchocerciasis (River Blindness) in Africa:
Editor's note: The articles listed above will be published online on Monday, May 20, 2013 at 5:00 p.m. US Eastern Time (2100 Hours GMT). Please note that the hyperlink to each AJTMH article will not go live until the paper has published. Print publication dates vary for each article.
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Top-Line Research Highlights:
1.) New Rapid Diagnostic Test for Worm Infection Provides Substantial Improvement Over Current Standard According to New African Field Study
Provides Compass to Guide Public Health Efforts to Halt Debilitating Lymphatic Filariasis (Elephantiasis)
A new diagnostic test strip to rapidly detect lymphatic filariasis – also known as elephantiasis – in human blood has significant advantages over the standard card test that has been used for more than a decade to map, monitor and assess the success of the massive global campaign to eliminate the disease.
"Like a compass, this new test will help guide global public health officials in their efforts to stop the spread of the disease," said lead author Gary J. Weil, MD, of Washington University School of Medicine in St. Louis. "It should help officials better assess the point at which the disease is no longer a threat to a community so they can stop administering mass drug treatment. This new test should also be a more sensitive tool for detecting resurgence of lymphatic filariasis infection before it gets out of control."
The test strip is expected to have a much longer shelf-life (two years) than the currently used card test (three months) and will be marketed later this year at a much lower cost.
Weil and colleagues from the Liberian Institute for Medical Research and U.S. Centers for Disease Control and Prevention (CDC) reported that while the BinaxNOW Filariasis card test has contributed to the early success of the global filariasis program the new Alere Filariasis test strip was easier to use and more sensitive. The test strip detected nearly 26 percent more people with lymphatic filariasis infection than the card test in a field study conducted in an endemic area in Northwestern Liberia (Lofa County). The study, published in the American Journal of Tropical Medicine and Hygiene, which also includes findings from laboratory testing at Washington University and the CDC, was the first independent evaluation of the new test strip.
Lymphatic filariasis is a deforming and disabling mosquito-borne disease that affects about 120 million people in 73 countries around the world. Worm larvae are deposited by an infected mosquito during a bite. Once in the human body the larvae migrate to the lymphatic system where they mature into adult worms. The thread-like parasitic worms damage lymphatic vessels that drain fluid from tissues, which results in swelling and deformity of the legs and male genitals. The Global Programme to Eliminate Lymphatic Filariasis (GPELF), launched in 1997, coordinates periodic mass drug administration (MDA) of antifiliarial medications (albendazole with either ivermectin or diethylcarbamazine) to more than 500 million people a year, making it the world's largest public health intervention program based on mass drug administration to date.
Note: Test development was funded by the Bill & Melinda Gates Foundation; both diagnostic tests evaluated in this study were manufactured by Alere Scarborough, Inc. The Alere Filariasis test strips were donated by the manufacturer and BinaxNOW Filariasis card tests were financed by the research project. The paper reports the results of an independent evaluation.
Contact: Gary Weil, MD, tel: +1-314-747-5198, gweil@dom.wustl.edu
Article 13-0089 "Laboratory and Field Evaluation of a New Rapid Test for Detecting Wuchereria bancrofti Antigen in Human Blood," by Gary J. Weil, Kurt C. Curtis, Kerstin Fischer, Andrew C. Majewski, Peter U. Fischer, Lawrence Fakoli, Lincoln Gankpala, Fatorma K. Bolay, Patrick Lammie, Sonia Pelletreau and Kimberly Y. Won
2. a) In a First for East Africa, Scientists Provide Detailed Evidence that Onchocerciasis (River Blindness) May Be Eliminated After 14 Years of Long-term Mass Drug Treatment
New research provides the first evidence in East Africa that long-term community-based drug treatment alone can interrupt transmission of onchocerciasis, a parasitic disease commonly known as river blindness. The study finds that after eight years (beginning in 1998) of treating residents annually with the anti-worming medicine ivermectin, followed by six years of semi-annual treatment with the drug, there is no evidence of the disease or its transmission in or around the Nile River town of Abu Hamed in Northern Sudan.
"This is the first report of elimination in a major isolated area and a big step toward eliminating river blindness in East Africa," said lead author Tarig Higazi, PhD, of Ohio University's Zanesville campus and Tropical Diseases Institute. "While previous studies have demonstrated that long-term annual or semiannual mass treatment with ivermectin have eliminated the disease in the Americas and West African nations of Mali and Senegal, these data show that we are further shrinking its reach by interrupting transmission and eliminating the disease in the northernmost endemic area of the world."
Higazi and his colleagues at The Carter Center and the Sudan Ministry of Health found during their assessment in 2011 that there were no signs of skin disease in 536 Abu Hamed residents, no evidence of parasite DNA in the more than 17,500 black flies collected, and no evidence of disease exposure in more than 6,700 school children who are considered sentinels for disease infection. The assessment met the World Health Organization (WHO) criteria for declaring disease transmission interrupted. Mass treatment was halted in 2012, and the WHO is expected to declare river blindness eliminated in 2015 in this area, once three years of post-treatment surveillance are completed.
According to the WHO, more than 18 million people worldwide are infected with onchocerciasis, with nearly 99 percent of those cases in Africa. The parasitic disease – which can cause severe skin ailments, debilitating itching, and blindness – is transmitted by black flies (genus Simulium) that breed in fast-moving rivers or streams. When a fly bites a human, it deposits larvae that mature into adult worms in the body. Ivermectin is effective at stemming the worm infestation and reducing the severity of the infection.
Contact: Tarig Higazi, PhD, tel: +1-740-588-1533, higazi@ohio.edu
Article 13-0112 "Interruption of Onchocerca volvulus Transmission in the Abu Hamed Focus, Sudan," by Tarig B. Higazi, Isam M. A. Zarroug, Hanan A. Mohamed, Wigdan A. ElMubarak, Tong Chor M. Deran, Nabil Aziz, Moses Katabarwa, Hassan K. Hassan, Thomas R. Unnasch, Charles D. Mackenzie, Frank Richards, and Kamal Hashim
2. b) Onchocerciasis (River Blindness) Could Make Comeback in Northwestern Uganda if Annual Drug Administrations to Fight Parasitic Disease Are Stopped, New Study Shows
Public Health Workers May Need to Increase Distribution Frequency to Achieve Elimination
Researchers report onchocerciasis (river blindness) could make a comeback in Northwestern Uganda if annual drug distributions to fight the disease are stopped. The study, conducted in the endemic region of Nyagak-Bondo, showed that while there was a significant reduction in infection after 18 years of community-based treatment with the deworming medication ivermectin, transmission has not been interrupted. Lead researcher Moses Katabarwa, PhD, of The Carter Center and Emory University and colleagues from the Uganda Ministry of Health found that children born even long after the drug distribution began in 1993 were still getting infected. A substantial number of adults were testing positive for microfilaria (worm larvae) as well.
"This study shows that there is truly no one-size-fits-all approach when it comes to stopping river blindness infection," Katabarwa said. "The amount of time and the frequency of treatment necessary to interrupt transmission and eliminate the disease could vary considerably among different areas because of environmental factors, the flies involved, the risk of drug resistance, or other issues."
While recent reports conducted in other West African nations (Mali and Senegal) suggested that there was no difference between 15-17 years of annual or semi-annual community-based treatment with the deworming medication ivermectin in eliminating transmission of the disease in those areas, annual treatments were not sufficient in the Nyagak-Bondo region. The authors report the data indicate that it may be necessary to increase the frequency of ivermectin treatments to twice per year to successfully interrupt transmission of the disease.
Contact: Emily Staub, tel: +1-404-420-5126, Emily.Staub@emory.edu
Article 13-0037 "Transmission of Onchocerca volvulus Continues in Nyagak-Bondo Focus of Northwestern Uganda after 18 Years of a Single Dose of Annual Treatment with Ivermectin," by Moses N. Katabarwa, Tom Lakwo, Peace Habomugisha, Stella Agunyo, Edson Byamukama, David Oguttu, Ephraim Tukesiga, Dickson Unoba, Patrick Dramuke, Ambrose Onapa, Edridah M. Tukahebwa, Dennis Lwamafa, Frank Walsh, and Thomas R. Unnasch
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