SANAA, 13 May 2008 (IRIN) - A local non-governmental organisation (NGO) has said it will take 8-10 years to eradicate onchocerciasis, a disease which leads to skin irritation and in some cases blindness, although much progress has been made in fighting the disease.

Isam Addin Awadh, head of the onchocerciasis control programme at the Charitable Society for Social Welfare (CSSW), told IRIN onchocerciasis was present in 34 countries, including Yemen. He said the average rate of infection in Yemen had dropped to less than 5 percent. "More than three years ago, the rate was 10-55 percent. Efforts to combat the disease should continue, otherwise it will spread again," he said.

According to Awadh, onchocerciasis is found in eight governorates - Taiz, Ibb, Dhamar, Hajjah, Sanaa, Raimah, al-Hudeidah, and al-Mahwit. Locally, the disease in its severe form is also known as 'sowda' or 'aswad' (black) as a result of the swollen, darkened skin changes it engenders.

Awadh said the CSSW began combating the disease in 2000 in five governorates after distributing medicines as part of community-based activities.

Mectizan - provided free of charge by the Mectizan Donation Programme is used to combat the disease.

"Community volunteers have weighing scales, and anyone under 15 kg is not given Mectizan tablets. The medicine is distributed every three months," Awadh said.

According to CSSW, 282,681 people benefited from Mectizan from 2000 to 2006. In 2007, there were 128 new cases in the five governorates.

Valley-dwellers at risk

Yassin al-Qubati, secretary-general of the Yemeni Association for Erasing Leprosy, told IRIN onchocerciasis was first discovered in 1955 in the governorate of Aden. He said the disease was found only in valleys that flow into the Red Sea, such as Seham, Sordod, Remaa, and Khamis Bani Saad.

The larvae that cause the disease are found in swiftly flowing water.

"We began combating onchocerciasis in 1989 in al-Ghail valley, Taiz Governorate, and found that 50 percent of the population was infected. By 2000 the disease had disappeared from that valley," he said.

Al-Qubati said onchocerciasis in Yemen was found in its non-blinding form and caused intense skin itching only, according to the World Health Organization (WHO) .

Causes of the disease

Onchocerciasis is caused by the filarial worm onchocerca volvulus. It is transmitted through the bites of infected blackflies of the simulium species, which carry immature larval forms of the parasite from human to human. When the larvae enter the human body, they mature to adult worms, which can later release up to 1,000 microfilariae a day.

WHO said these move through the body, and when they die they cause a variety of conditions, including blindness, skin rashes, lesions, intense itching and skin depigmentation.

According to WHO, about 18 million people have onchocerciasis worldwide, and about 270,000 are blind.

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