Category Archives: Onchocerciasis

A Test For River Blindness

 

A boy helps Samuel Nicol, (age unknown) who suffers from onchocerciasis, walk through the village of Gbonjeima, Sierra Leone. Olivier Asselin, 2012.

A boy helps Samuel Nicol, (age unknown) who suffers from onchocerciasis, walk through the village of
Gbonjeima, Sierra Leone. Olivier Asselin, 2012.

Re-posted from Greg Laden’s Blog on ScienceBlogs

River blindness, also called Onchocerciasis, is the result of the infection of several different eye tissues by the nematode Onchocerca volvulus. The bacterium Wolbachia pipientis lives symbiotically in the gut of the nematode, and escapes the small roundworm to cause an inflammatory response in human tissues, which results in damage to the tissue. These infections can occur in a number of different human tissues causing a variety of effects, but when the eye tissues are involved, the result can be river blindness. It is endemic and widespread in several areas of Africa, as well as more restricted areas in South America and the Middle East.

Treatment of the disease involves killing the bacterium, which in turn kills the host nematode, using various anti-biotics. However, as we have learned over recent decades, widespread use of antibiotics can be less than ideal because this can cause selection for resistant strains so that treatment can become generally ineffective across an affected population. Ideally, there would be a reliable test for river blindness infection that would allow more targeted use of treatments.

A research team at Scripps has just published a paper in PNAS that may lead to such a treatment. The team examined urine samples from people who are known to be infected with the nematode Onchocerca volvulus and its attending Wolbachia pipientis bacterium with those who were not thought to be so infected. A massive laboratory based hunt for differences in the contents of the urine was carried out, and one molecule was identified as unique to the infected humans. This was N-acetyltyramine-O,β-glucuronide, which started out as a neurotransmitter found in the nematodes while they are young, which is then converted to N-acetyltyramine-O,β-glucuronide in the human body and eventually secreted in the urine.

The nematode has a somewhat complex lifecycle in which the very young worms infect various tissues and reproduce there, causing the damage to the tissue via the bacterium’s release. This neurotransmitter seems to be unique, or nearly unique, to these young worms. This is important because the nematode is probably widespread in humans in the endemic areas, but as relatively dormant adults found here and there throughout the body. It is only the young reproducing worms that cause the river blindness. Therefore, N-acetyltyramine-O,β-glucuronide specifically identifies individuals at risk of tissue damage to the eyes.

The test is not yet ready for prime time. There needs to be a field test that can be administered easily in conditions where there are only minimal or no clinical facilities. The test materials have to be reasonably inexpensive and not require special handling such as refrigeration. Ideally, this would consist of a urine test strip as have been developed in the past to test for blood sugar levels or pregnancy.

Another important outcome of this finding is the method itself, which the researchers have dubbed “Metabolome-mining.” (The term “metabolome” refers to the full set of metabolites to be found in a particular organism or tissue, similar to the term “genome” for the full set of genes.)

More information will be available at the Scripps Research Institution web site.

Globisch, D, Moreno, A, Hixon, M, Nunes, A., Denery, J., Specth, S., HYoerauf, A, & Jand, K (2013). Onchocerca volvulus-Neurotransmitter Tyramine is a Biomarker for River Blindness PNAS

Keeping score: Will the new NTD Scorecard keep global action on track?


By Simon Bush,
Director of Neglected Tropical Diseases at Sightsavers. See his recent article in the Huffington Post here.

Today sees the publication of an NTD Scorecard which will bring further transformation to the way global partners, from endemic governments, and pharmaceutical companies to NGOs, are working together to achieve the elimination of this group of debilitating diseases.

Developed by the London Declaration partners and published alongside From Promises to Progress, a new report on NTDs, the Scorecard will help translate the aspirational vision of elimination of ten of the NTDs by 2020 into a reality.

When I first started working on NTDs 13 years ago, I never would have imagined progress like this. Elimination of NTDs such as blinding trachoma and river blindness (onchocerciasis) seemed such a distant goal. How things have changed!  We are now seeing promises turn into action which will make a colossal difference to the lives of over a billion people who are affected by NTDs.

The Scorecard sets out the strategic milestones that are crucial if we’re going to see real progress on these ten NTDs – in terms of raising funds, conducting research and development, and ultimately delivering the right number of treatments, to the right people, in the right communities. It’s all about achieving the scale-up needed. Continue reading

NTD Success Story: Guatemala Eliminates Onchocerciasis Transmission in Huehuetenango

Another battle in the fight against neglected tropical diseases (NTDs) has been won in Guatemala, where onchocerciaisis transmission has been eliminated in Huehuetenango.

A recent article in the Journal of Parasitology Research evaluated onchocerciasis transmission in the department of Huehuetenango in western Guatemala after 22 rounds of mass drug administration (MDA) over 13 years. In 2007-2008, prevalence of infection was determined to be zero percent through eye examinations of residents, antibody detection in school children and parasite detection in black flies. Following the results of this evaluation, mass treatment was halted in 2009 and post treatment surveillance of parasite prevalence in black flies was conducted from 2009-2011. Infection remained at zero percent, validating that transmission had been eliminated in the area.

Onchocerciasis, also known as river blindness, is caused by the parasite Onchocerca volvulus and is transmitted to humans by the bite of black flies. Infection with the parasite can produce nodules, inflammation, discoloration and itching of the skin, as well as lesions that can lead to blindness. Onchocerciasis is found in 37 countries across the world.

The Onchocerciasis Elimination Program of the Americas, or OEPA, was established in 1992 with the goal of supporting national programs in LAC countries to provide twice yearly MDA of ivermectin to a minimum of 85 percent of the eligible population at risk. The Guatemala Ministry of Public Health, with the assistance from OEPA, began MDA for onchocerciasis in 1996, and since 2002 has reached the targeted coverage of the eligible population through twice-yearly MDA. There were four endemic foci for onchocerciasis in Guatemala. Before this study, transmission in two of the four foci had already been declared eliminated. With this recent evidence of elimination in Huehuetenango and with post treatment surveillance being conducted in the fourth foci, Guatemala is well on its way to request the WHO certification of nation-wide elimination in 2015.

How a Nigerian General Became an Advocate for Stopping River Blindness

Lieutenant General (Ret.) Theophilus Yakubu (TY) Danjuma knows river blindness firsthand. As a Nigerian who grew up in a country with one of the highest rates of river blindness (also known as onchocerciasis) infection in the world, he has not only witnessed the devastation this disease can bring to families and communities, but has also suffered from the disease himself.

River blindness produces rashes, skin lesions and severe skin inflammation that can make the skin change color and lose elasticity. People suffering from the disease often face daily social humiliation and isolation, and infected children struggle to pay attention in school because of intense itching. River blindness, however, is aptly named. Its most debilitating symptoms are severe visual impairment and irreversible blindness.

General Danjuma’s experience with this disease began in the 1960s. While leading a company of soldiers in Nigeria, he was bitten by the Simulium black fly that transmits the worm larvae that cause river blindness. For two years, the larvae spread throughout his body, maturing into adult worms and releasing bacteria that eventually trigger an immune system response. He awoke one morning with swollen eyes and itchy, inflamed skin. General Danjuma successfully underwent two weeks of treatment and experienced no lasting symptoms, but says he has never forgotten the sight of his own skin sample under the microscope at the local clinic. He still shivers at the memory of tiny worms swimming in and out of view under the lens.

General Danjuma is the Grand Patron of an important NGO based in Jos, in Northern Nigeria. The NGO, The Mission to Save the Helpless, better known by its acronym MITOSATH” is well known to the health team in the Africa Region as an important partner of African Programme for Onchocerciasis Control (APOC). MITOSATH is also among the most active NGOs in Nigeria contributing to the control of river blindness other neglected tropical diseases.

Controlling River Blindness in Africa: Setting an Example

A young boy leads a man impacted by river blindness. Photo by Olivier Asselin.

 

 

 

 

 

 

 

 

 

 

 

 

 

When river blindness control programs were first implemented in the 1970s, up to half of all adults in some hard-hit communities had gone blind from the disease. This tragedy caused many Africans to abandon their ancestral homes and livelihoods; the economic losses were estimated at US$30 million. The first Onchocerciasis Control Programme focused primarily on spraying insecticide over infected areas in order to minimize the prevalence of the black fly, preventing transmission of the parasitic worms from person to person, and eventually incorporated treatment with Ivermectin, the drug that treats river blindness, when it became available.

With the help of the World Health Organization and the World Bank in 1995, this program was expanded and renamed the African Programme for Onchocerciasis Control (APOC). Rather than attempting to control the black fly population, APOC sought to control the parasitic worms in humans through community-directed treatment with Ivermectin in 19 countries. Treatment with Ivermectin successfully kills the worms in the people who have them, thereby disrupting transmission of the disease.

Merck & Co. donates Ivermectin to Nigeria (and other countries in need), and APOC trains volunteers to distribute the drug in communities. Today, APOC provides Ivermectin to more than 96 percent of endemic communities in Nigeria, reaching more than 23 million people. Until everyone is treated, however, the risks of re-infection and new outbreaks remain. River blindness is still present in most Nigerian states, including Taraba state where General Danjuma was born. The disease continues to deeply impact communities and the lifetime productivity of the 31 million Nigerians at risk.

Now a successful businessman and politician, General Danjuma’s personal experience with river blindness and the success of MITOSATH and APOC motivated him to donate US$1 million to the program in 2010. With his donation, he hopes to invigorate interest in public health challenges in rural Africa. General Danjuma noted that, “these are not the neglected diseases of tropical Africa, but rather the diseases of neglected people.”

General Danjuma’s crusade to raise the profile of rural health issues has already gained momentum. Following his example, in 2011, the government of Nigeria pledged an additional US$5 million to APOC to assist with its control efforts. General Danjuma hopes that other countries and the private sector will join the movement to eliminate this debilitating disease once and for all.

 

In March 2012, General Danjuma participated in a panel discussion at the Center for Strategic and International Studies. Read our blog post on that event here.