Now available, contraceptives for elephants

PARIS, SEPT 14: An innovative contraception is set to help Africa's game parks prevent elephant overpopulation, a phenomenon that is immen...

PARIS, SEPT 14: An innovative contraception is set to help Africa’s game parks prevent elephant overpopulation, a phenomenon that is immensely destructive to vegetation and other wildlife. South African and US researchers say they have tried out the drug on female elephants in the famous Kruger National Park and declare it to be a safe, successful and reversible way of preventing pregnancy. The substance is an immuno contraceptive vaccine, which works differently from implanted hormone contraceptives.

Like all vaccines, this one primes the immune system to deliver antibodies that attack an invader. In this case, the target is not a foreigner, but the elephant’s own egg — specifically the zona pellucida, the clear coat of proteins that surrounds it. By attacking the zona pellucida, the antibodies disrupt the crucial biochemical dialogue that takes place between sperm and egg at their moment of contact, rendering the animal sterile.

The vaccine was derived from the pig’s eggs, whose zona pellucida is very similar to that found in elephants. The team vaccinated 41 adult female elephants, placed radiocollars on them to track their movements, and checked them again 10 months later.

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They found that the shot, which was followed by two booster injections delivered by helicopter two and four weeks later, reduced pregnancies by up to 70 per cent compared with a control group that was monitored at the same time. The antibodies persisted for 12-14 months before fading away, enabling the elephants to conceive again. "This indicates that the vaccine is reversible, and that it has no deleterious effect on the ovary and its cyclicity," they write.

The team are from the University of Georgia, the Kruger National Park, University of Pretoria and ZooMontana of Billings, Montana, a pioneer in the use of immuno contraception to curb overpopulation of animals or pests in a habitat where there are no predators.

The technique has been used before with mice, rabbits, horses and other large animals, but this is the first research to prove that it also works with wild elephants.