Hyraxes May Lose Protected Status in Israel to Prevent Spread of Leishmaniasis

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Hyraxes near Tiberias
Hyraxes near TiberiasCredit: Gil Eliahu

Rock hyraxes in Israel may lose protected status for three years in an attempt to curb the spread of leishmaniasis, a parasitic infection they host that causes skin ulcers.

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The Environmental Affairs Ministry published a notice for public comment on the plan last week.

If the plan goes through, rock hyraxes would be reclassified as a pest and would face culling in addition to other moves to distance them from human populations.

The Nature and Parks Authority in Israel handles population control of protected animals, such as jackals and boars, without revoking their protected status. Shooting protected animals requires a permit from the authority and must be done under its supervision. But if the hyraxes lose protection, it's open season.

After three years the results of the moves would be evaluated and the status of the hyraxes would be reevaluated.

Conservation experts warn that uncontrolled moves could lead to the hyraxes' extinction in Israel. Prof. Amie Ilani of Bar-Ilan University points out that unfettered hunting almost led to the extinction of the mountain gazelle in the Golan Heights. Prof. Ilani also points out that one reason for the mad proliferation of hyraxes in the hills of Israel is that most of their predators, such as the Israeli leopard, have gone extinct.

The hyrax-human connection

Rock hyrax in JerusalemCredit: Emil Salman

Hyraxes are one of around 70 different mammals – humans are another – that can get leishmaniasis. Unable to protect their beds with netting, for instance, hyraxes have become a natural reservoir of the leishmania parasite, as was demonstrated in 2010.

A 2008 study conducted in the West Bank settlement of Ma’aleh Adumim found that the human cases of leishmaniasis were clustered in two neighborhoods located by slopes and caves inhabited by rock hyraxes.

It should be noted, however, that humans don't catch leishmaniasis from hyraxes, which don't bite people. Rather, both humans and hyraxes contract the disease from the bite of parasite-carrying sandflies. The disease can also spread when a sandfly bites an infected hyrax before biting a human. In the wild, hyraxes can live up to nine years – plenty of time to catch the parasite and share it with us.

The previous study showed that about 10 percent of the hyraxes trapped around Ma’aleh Adumim had the condition. Other work has shown foci of the disease in the Judean Hills, western Samaria and northeast of the Sea of Galilee.

Actually, Israel has three endemic species of leishmania: two, leishmania major and Leishmania tropica, cause shallow to deep skin ulcers that are hard to treat but seldom dangerous. The lesions may also appear in the mouth and nose.

It's the third kind, leishmania infantum, that can kill, by attacking the inner organs. There is still no vaccine for the condition. Treatment, which may take months to take effect, involves painful injections – but in any case, the lesions may leave scars. Also, the parasites can develop immunity.

All three variations are usually diagnosed by seeing the parasites under the microscope.

"Leishmania is a serious disease and should be handled by preventing its distribution," says Prof. Yoram Yomtov of Tel Aviv University. There are ways other than killing the rodents: covering hospitable piles of rocks with dirt or concrete; or relocation, guiding their flight with temporary fencing, for instance. All would be costly however – hence the idea of lifting their protection and reclassification as a hazard, like cockroaches or rats, he says. "I wouldn't be surprised if the local authorities begin poisoning the hyraxes, which is also highly hazardous for people. Predators and raptors will eat the poisoned hyraxes, causing widespread secondary poisoning."

Half a billion at risk

The World Health Organization estimates that over 12 million people have leishmaniasis presently, and 500 million people are at risk of infection in Africa, Europe, Asia, and the Americas.

When the parasite enters our blood, instead of evading our the white blood cells, the immune systems' warriors – the parasite allows itself to be swallowed by them, and multiplies inside these cells, ultimately affecting other body tissue. One result is that our white blood cell count drops. Another is the disease, which may erupt only weeks or months after infection.

There is hope though that more effective treatments could be coming.

Visceral leishmaniasis is the second most deadly parasitic condition after malaria, says parasitologist Albert Descoteaux, who with medicinal chemist Prof. Steven LaPlante is working on developing molecules for new treatments that will hopefully be cheaper, more effective and less painful than the present ones. Their efforts – and the challenges involved were described this week in the journal of the INRS.

Descoteaux and LaPlante have identified two families of molecules that could be the basis of future drugs against this pernicious, persistent parasite: indole and indazole derivatives.

But it's early days. Stay tuned and if you're out and about in sandfly territory, wear insect repellent and/or long sleeves. Remember, it isn't the hyrax (or the dog) that's sticking its proboscis into your skin.

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