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New disease threatens humans, livestock

A dirty environment is conducive to the spread of myiasis.
(Mohammed al-Jabri/IRIN)

Specialised field teams in three provinces are trying to tackle the spread of myiasis, the infestation of human or animal tissue with fly larvae (maggots) - a disease which has not been seen in Yemen until very recently.

[Read this report in Arabic]

Ghaleb al-Eryani, director-general of the General Department for Animal Resources (GDAR) at Yemen’s Ministry of Agriculture, told IRIN on 18 February that about 1,500 animals and eight people had contracted the disease since it first appeared in December 2007 in al-Dhaher village, Saada Province, near the border with Saudi Arabia.

"The disease was combated immediately… but later it spread to other districts and the neighbouring province of Hajja," al-Eryani said, adding that the disease had also hit al-Zahrah district in the western province of al-Hudeidah.

"The teams have cured all the discovered cases by giving them anti-parasite medicines and spraying parasiticide. Combating the disease is very costly and beyond the government's capabilities. On average the infected animal or human needs US$10 for the required medicines," he said.

Myiasis is the infestation of tissue with fly larvae. It is widespread in the tropics and subtropics of Africa and the Americas, but occurs with significantly less frequency in most other areas of the world. The disease is also known as `fly-strike’ `fly-blown’ or `New World’.

''Combating the disease is very costly and beyond the government's capabilities. On average the infected animal or human needs US$10 for the required medicines.''

The GDAR said it had notified farmers not to move their animals without the supervision of a veterinary officer for fear that they might move to infected places.

Al-Eryani said people need to be aware of the disease; combating it required a clean and healthy environment. He said the poor could be the most vulnerable as 75 percent of Yemen's 21 million inhabitants live in rural areas and “almost all people in rural areas rear animals in their houses. The environment encourages the spread of the new disease."

"The situation is very worrying. The initial loss Yemen might face is 22 billion riyals [about US$111,000,000] in terms of livestock. There are 15 million sheep; 1.4 million cattle and 250,000 camels in the country," he added.

Epidemiology

According to al-Eryani, the disease is caused by a fly known as screwworm or `New World’ (because of its prevalence in the tropics) - a species of parasitic fly whose maggots eat the living tissue of warm-blooded animals, including humans. The screwworm fly is about twice the size of a regular house fly. It is greenish-blue in colour and has large reddish-orange eyes.

Infestations can occur in any open wound, including cuts, castration wounds, navels of newborn animals, and wounds caused by tick bites. The wounds often contain a dark, foul-smelling discharge. Screwworm larvae feed only on living flesh, never dead tissue. Once a wound is infested, the screwworm can eventually kill the animal or human, literally eating it alive.

Screwworm females can lay up to 400 eggs at a time in the exposed flesh of either animals or humans and they can hatch into larvae in as little as 12 hours. A single adult female can lay as many as 2,800 eggs during its 31-day lifespan. The hosts are usually mammals, occasionally birds and, less commonly, amphibians or reptiles.

"This fly can fly over 120km and deposit its eggs in animal's or human's wounds. It also puts its eggs in the animal's anus and vagina. Then the egg develops into a larva, which later grows in the form of a snail," he said, adding that the infected organ might need to be amputated. "The disease does not directly lead to death but if not treated it causes death," he said.

Bristol University’s Veterinary Parasitology and Ecology department has described in detail the different forms of the disease.

maj/ar/cb


This article was produced by IRIN News while it was part of the United Nations Office for the Coordination of Humanitarian Affairs. Please send queries on copyright or liability to the UN. For more information: https://shop.un.org/rights-permissions

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