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NATIONAL GEOGRAPHIC VIDEO ELEPHANT BIRTH CONTROL VACCINE
- Please click here to view the video
The Makalali Elephant Immunocontraception Program is the flagship program in elephant immunocontraceptive studies worldwide. As elephants are long-lived animals, our research is directed to the long-term monitoring of the same population to address issues relating to long-term social, demographic and ecological impacts. Whilst we have addressed these concerns in the medium term (10 years), longer studies will cement this methodology and replace the way in which we manage elephants in the future. Please help us by donating directly to Elephant Research.
As part of this Assessment, a group of local and international scientists report on an alternative method of elephant population control called PZP (Porcine Zona Pellucida) immunocontraception. After the initial trials of the immunocontraception in the Kruger National Park (KNP) (1996 – 2000), the team have been studying the follow-up phase at The Greater Makalali Private Game Reserve, outside Hoedspruit (2000 – present). These studies have spanned approximately 12 years. Unfortunately, the hormonal trials run in conjunction with the immunocontraceptive trials in the KNP have incorrectly labelled both methods of elephant contraception as socially disruptive, displaying severe behavioural anomalies. Whilst this was clearly demonstrated with the hormonal trials, a comprehensive, long-term study at Makalali has revealed that immunocontraception is a safe, reliable, reversible, efficacious means of fertility control with no behavioural anomalies.
In October 2007, the research team immobilized 4 elephant cows from the Makalali population for the purposes of replacing their radio collars with satellite collars, and for conducting transrectal ultrasonography. The ultrasounds would demonstrate the elephant’s pregnancy status as well as provide an indication of the animal’s reproductive health. As expected, none of the elephants were pregnant, and no pathologies were evident in the reproductive tract demonstrating that the medium-term use of PZP does not have any deleterious physiological effects. Blood and faecal samples were collected for hormone analysis to determine whether or not the cows had recently cycled. The results indicated that the cows all had cycled and reported normal ovarian function.
Faecal samples from the Makalali population are being collected to provide a more objective method to assess oestrous and stress and to track individual cow cycles over time. This component of the study i.e. oestrus cyclicity and physiological stress response to immunocontraception in the female African elephant is being conducted together with Prof. Henk Bertschinger at the University of Pretoria.
| The Makalali study has further demonstrated that the vaccination does not affect pregnancies in progress (irrespective of the gestational stage) and a non-pregnant female will be immediately contracepted from the first vaccinational series. Makalali’s detailed population history allowed for a predictive model to project population sizes through to 2010 under the current management strategy, which allows conception in young cows before being contracepted. This is necessary for the social well-being of the herds and the population’s demographics. Even under this strategy, the Immunocontraceptive will effectively reduce the population growth rate by 70% for the period 2003 through 2010. |  |
The aims of the Makalali study were to further investigate the medium-term and sustained use and effect of PZP on cow and bull societies and their behaviour. For reserves that are largely eco-tourism driven, the implementation of a PZP program will have little effect on game-drive and safari activities. The shorter vaccine administration demonstrated by the helicopter darting appeared to have a more consistent effect on the herds, with the least shift in core range during and after darting.
The prime concern raised is that of the effect of the vaccine on reproductive behaviours. Under the PZP treatment, the target animal displays a normal oestrous cycle, cycling every 15-16 weeks, because although copulation still occurs, conception does not. Therefore, under the PZP contraceptive, the frequency of mating and its accompanying disturbances is assumed to be far more frequent. Thus, with an increased frequency of oestrus, there is the potential for change in the frequency of association of both sexually active musth and sexually active non-musth bulls with breeding herds as both sets of males compete for oestrous females. In fact, bull association with herds decreased over the years, probably an effect of aging in this relatively young population. The decrease in herd-bull association further illustrated that the PZP implementation did not affect the Makalali’s bull hierarchy i.e. there were far more non-musth sexually active bulls than musth sexually active bulls and even in the absence of musth, mating and consort behaviour was highest in the three dominant musth bulls. Furthermore, the non-musth sexually active bulls did not increase their associations with the herds. Thus, the treatments did not affect bull hierarchy or cow selection. The results from this study demonstrate that there was no aberrance to suggest that the PZP has any adverse effects on the behaviour of the treated cows, their matriarchal groups or bulls.
There is a concern that contraceptive implementation may be cost prohibitive. The Makalali study has demonstrated that the highest costs incurred during contraception implementation are based on the helicopter costs, or more specifically, the costs of ferrying the helicopter to the site. Implementation and costs amount to R880–R1 000/elephant, fully inclusive of the darts, vaccine, helicopter and veterinary fee.
The results demonstrated in the Makalali study have resulted in the implementation of immunocontraception as an elephant management tool in 10 reserves including Phinda, Welgevonden, Thornybush and recently, Tembe Elephant National Park. However, in vitro studies have been underway with a different type of vehicle with the PZP vaccine. This is the so-called “one-shot vaccine” that combines the initial three vaccinations from the KNP and Makalali designed protocol into a single vaccination. Thus, during the first year, only one dart per cow is required. Furthermore, the long-acting pellets are released at 1, 3 and 12 months, necessitating the first booster during the third year only. Thereafter, a single annual booster will be necessary to maintain immunity and contraception. The first field trails were conducted in free-ranging elephants in May 2007 at Karongwe Private Game Reserve.
The KNP trials and the Makalali study have culminated in almost twelve years of intensive investigation into the social and behavioural consequences of immunocontraception in African elephants. Similar studies have been conducted on other long-lived animals i.e. horses (with treated animals developing new age classes i.e. 21-25 years, and > 25 years), with same-population studies spanning more than 15 years on Assateague Island National Seashore (Kirkpatrick & Turner 1996, Turner et al. 2002). With such comprehensive studies demonstrating that PZP contraception causes no long-term behavioural changes, managers need to assess PZP immunocontraception as a realistic alternative management tool, particularly as part of a longer-term management strategy. It is anticipated that the results of this groundbreaking research project will assist game reserves in managing their elephant populations, as the only alternatives have been culling or translocation, neither of which are entirely suitable or feasible management methods in all reserves. On a larger conservation scale, immunocontraception has enormous potential to change the way in which we manage our elephant populations in the future.
How does the pZP vaccine work?
A membrane known as the zona pellucida (ZP) surrounds all mammalian eggs. This membrane contains several glycoproteins, one of which is thought to be the sperm receptor (the molecule which permits attachment of the sperm to the egg during the process of fertilisation). The PZP (porcine zona pellucida) vaccine is derived from pig eggs. Once injected, the vaccine stimulates an immunological response to produce antibodies that attach to the ZP of the target animal, thereby preventing fertilization as sperm cannot attach to and penetrate the egg.
The PZP vaccine is not a hormone! Therefore, to date, no observed behavioural or physiological aberrancies have been noted. All normal reproductive functions are maintained in the target animal, namely oestrous cycles, lactation and foetal development (in pregnant animals).
How is immunocontraception implemented?
First and foremost, a properly defined elephant management plan needs to be in place that will outline potential problems with regards to the elephant population and also make provision for their active management. Thereafter, it can be determined whether or not immunocontraception will be a viable management option for the reserve.
Target animals then need to be identified. This target group consists of the reproductively active females within a population. The vaccine can be administered remotely to free-roaming elephant, either from the ground or air. Important: The vaccine administration must reflect the conservation and ecological requirements of the specific reserve. Each of the target animals selected will receive an initial vaccination followed, three weeks later, by a booster. This will contracept the animals for one year. Thereafter, the animal will receive an annual vaccination consisting of one booster only.
The population should then be monitored on a regular basis so as to note any abnormalities. Re-assessment of the population should take place on an annual basis. Bare in mind that this is a biological control method aimed at slowing down and ultimately stabilizing an elephant population’s growth rate, and is not aimed at stopping births completely.
Immunocontraceptive results at Makalali Private Game Reserve
For the initial, 1st and 2nd vaccinations in 2000, 2001 and 2002 respectively, all the animals were darted from a vehicle or from foot. During this period, none of the elephants were radio-collared. However, 23 animals received their initial, primary, secondary and annual boosters remotely over a 3yr period. This proved that the PZP vaccine could be successfully and remotely delivered to free-roaming elephants in a small game park (refer to publications).
Behavioural, reproductive and spatial monitoring of the Makalali elephants has been underway since 1998. As a result, an extensive database exists on the animal’s seasonal movements, herd associations, bull/cow interactions and reproductive behaviour. To date, the only negative effect on behaviour has been an increasing wariness to the vehicle used for darting and a change in the herd’s spatial utilisation, primarily during the administration of the initial and subsequent booster vaccinations. However, soon after completion of the initial vaccination programme, the animals resumed normal movement patterns and were once again relaxed with the vehicles. No further behavioural anomalies have been recorded i.e. no separation of vaccinated females from family groups, herd fragmentation etc. Bull/cow interactions have occurred and recorded as normal.
The last target animal to have calved (as a result of being pregnant prior to contraception) was recorded in August 2002 (Delsink, personal observation). Thus, for the period August 2002 to July 2004, no contracepted cows have calved i.e. 0% growth has been achieved. However, to testing the reversibility of the vaccine, a number of treated cows were removed from the program. Two of these cows have subsequently calved illustrating that there are no side effects or concerns with the long-term treatment of the vaccine. Visit http://www.globalpost.com/dispatch/south-africa/090225/planned-parenthood-elephants for a video and update on the first reversal cow Smelly and her calf.
The Makalali study demonstrates that immunocontraception offers managers an alternative management tool that is safe, effective, reversible, non-lethal and practical in stabilizing elephant populations.
The advisors and participants of this project include:
1 The Humane Society of the United States (principal sponsors).
2 Ms Audrey Delsink and Mr Ross Kettles, Greater Makalali Private Game Reserve, PO Box 1009, Hoedspruit, 1380, South Africa.
3 Mr JJ van Altena, Catchco Africa, PO Box 1148, Highlands North, 2037, South Africa.
4 Prof. Henk Bertschinger, University of Pretoria, P O Box 75058, Lynnwood Ridge, 0040, South Africa.
5 Dr Jay Kirkpatrick, Science and Conservation Center, ZooMontana, 2100 South Shiloh Road, Billings, MT 59106, USA.