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lion study tour; Serengeti lions location
The Serengeti National Park is located in Tanzania, in East Africa.
Most people going on a study safari will either drive or fly from
Arusha, Tanzania.
Within the Serengeti National Park, the serengeti lions research center
("LRC") scientists study 15 lion prides and other nomadic lions located
in the South-Eastern portion of the Park in addition to studying the
prides living in the Ngorongoro Crater. serengeti lions virus study;
Distemper Virus Killing Lions, UT Researcher Says in Nature
lion study tour
KNOXVILLE,
Tenn. -- A virus normally found mostly in dog-like animals has killed a
third of the lions in Africa's Serengeti National Park, a University of
Tennessee scientist reports in the current issue of Nature.
lion study touri; Dr. Linda Munson,
a pathologist in UT's College of Veterinary Medicine,
said a 1994 outbreak of a type of canine distemper virus,
or CDV, has killed more than 1,000 lions in the Serengeti
and Masa Mara areas of East Africa since 1993.
lion study tour; CDV is thought to
have caused several fatal epidemics in foxes, wild dogs
and other animals in Africa and elsewhere, but the outbreak
identified by Munson's research team is the first known
to be fatal to lions.
The
source of the epidemic was probably the domestic dogs belonging to
villagers living near the park, Munson said. An outbreak of distemper
among these dogs, most of which are not vaccinated, preceded the lion
epidemic, she said.
lion study tour; The
virus may have been spread to the lion population by hyenas, which live
among both domesticated dogs and lions, she said.
''CDV
is a canine virus that for years has sometimes affected raccoons,
ferrets, and just a few cases in cats,'' Munson said. ''But something
happened about 1991 and it started affecting big cats in zoos, and then
we had the big epidemic in 1994, and it's also affecting hyenas now.''
serengeti lion study tour
Munson,
whose work is primarily funded by a faculty research grant from UT,
says she does not know why the virus suddenly extended its range of
hosts and became fatal to lions. She is part of an international
research team tracking the virus globally to see if it has affected
other species of carnivores.
African
government officials have implemented a program to vaccinate domestic
dogs near the Serengeti, Munson said. The epidemic seems to have
subsided and the death rate of serengeti lions has returned to normal,
but future outbreaks are a threat to endangered species, she said.
''The
CDV epidemic clearly emphasizes the need for continued monitoring for
infectious diseases in valuable wildlife resources and for initiating
vaccination programs for domestic animals in contact with wildlife,''
Munson said
lion study tour; Danger to serengeti lions
Burgeoning human population growth around the Western edges of the park
poses a great threat to big cats and other predators that roam the
Serengeti plains. Many of the villagers living outside the park own
dogs, and these dogs oftentimes are not vaccinated against such common
diseases as rabies or CDV. When these dogs intermingle with Serengeti
predators at kill or scavenge sites, viruses such as CDV that can be
spread through mucus secretions have a means by which to jump from
domestic to wild animal populations. In the case of the CDV outbreak of
big cats in the Serengeti in 1994, it is thought that hyenas
intermixing with domestic dogs at one of these sites contracted the
virus and then spread it to other predators at different kill sites
throughout the park. How the fatal virus was able to make the leap from
afflicting domestic dogs to threatening to wipe out a sizable lion
population was a question scientists did not have any answer to. And if
the virus could do so much damage this time around, what, if anything,
could be done to protect the lion population from future outbreaks?
tanzania lion study tour; Description
serengeti lions
The
Serengeti game reserve in Tanzania, Africa is one of the largest
wildlife areas left in the world and is known in part for its
well-documented and studied lion prides. Here, thousands of antelope,
wildebeests, and other herbivores carry on a daily life and death
struggle with the hyenas, jackals, cheetahs, and lions that inhabit the
reserve. The income derived from the thousands of tourists that
annually visit the park is a key source of revenue for the Tanzanian
government.
Several years ago, a
mysterious virus appeared among the thriving serengeti lions population
in 1994 and proceeded to wipe out a third of the population before the
eyes of baffled scientists worldwide. It was only after the virus had
run its course several months later that the culprit was found: Canine
Distemper Virus (CDV). Previously thought to only afflict dogs and a
small number of other mammals on a limited scale, its discovery lead
scientists to wonder how this potent virus had jumped species with such
lethal results.
The
Serengeti National Park is a 15,000 square kilometer ecosystem and a
place where natural preservation and economic development are on equal
footing. In 1994, there were an estimated 3,000 serengeti lions , the
largest population of big cats in the world.
Between January and March of that year,
11 lion carcasses were found - representing a dramatic
increase in mortality from previous years and indicating
to observers that there was a serious epidemic stalking
the serengeti lions. Tourists, many flying in hot-air
balloons over the park to get a better view of the wildlife,
were the first to notice that the serengeti lions were
dying. One of the first lions suspected of suffering from
CDV-like symptoms was observed on February 3, 1994 and
was identified because of the uncontrollable twitching
and convulsions that wracked its body. After watching
many of the serengeti lions dying or after examination
of their corpses, no one scientist knew why the outbreak
had been so sudden or severe or if in fact it was CDV
that was killing the cats. At least 40 serengeti lions
had died since the outbreak started in February and some
of the largest and best-studied prides had been wiped
out.
Tanzania lion study tour
In
fact, by early that year, approximately a third of a well- known
serengeti lions population study group of 250 was culled by the virus.
There was nothing experts could do to stop the current outbreak of the
virus except to let it run its natural course. The only vaccine they
had was of a weakened live virus and they didn't want to use it because
of the small chance of infecting healthy serengeti lions (Morrell 1994,
1664). Fortunately, the virus did not kill all those lions that were
infected so that the survivors will have immunity against future
outbreaks.
As investigators
suspected and later confirmed through extensive scientific analysis,
the animals of the Serengeti were dying of a canine distemper virus
(CDV) that belonged to a morbillivirus family or a virus very similar
to it. CDV is a viral disease that causes severe neurological symptoms
and usually death (Leary 1994, 13). Serengeti lions that were severely
affected almost inevitably died. CDV kills by attacking the
respiratory, gastrointestinal, immune, and central nervous systems of
its victims.
tanzania lion study tour; It
affected the lions' brains and caused facial twitching, flailing paws,
and convulsions. Other symptoms included: lions looking off color with
dull coats to complete paralysis. The virus struck down lions of all
ages throughout a 1,000 kilometer area within a few weeks of the
initial outbreak.
Some mammals have their
own version of the canine distemper virus such as seals, dogs,
black-footed ferrets, and livestock (Miller 1994, 5). The virus strikes
humans in the form of measles. CDV can be so pervasive that it nearly
wiped out the black-footed ferret population in the Western U.S. in the
1980s. The virus had occurred in lions and leopards in American zoos in
earlier years but never was such a large-scale epidemic among big cats
observed previously in the wild.
The
disease is spread through fine droplets of an animal's breath and is as
easily transmitted as a cold. For instance - a hyena or jackal
scrapping with domestic dogs over a carcass could have picked up the
infection and passed it along to the lions in the park in the same way
(drooling, snapping, or biting) (The Economist 1994, 76). It is thought
that hyenas were the most likely vectors of the virus because they
travel great distances and intermingle with both lions and domestic
dogs at separate kill and scavenge sites within and without the park.
Nomadic lions (not attached to any pride) could also have contributed
to CDV dissemination.
The
high densities of these susceptible carnivores at kill sites could have
provided an ideal environment for CDV amplification and transmission.
tanzania
lion study tour; Even though several suspected vectors were identified,
no one knew why there was a sudden outbreak within the serengeti lions
in 1994 because canines and felines had lived together for many years
without the virus jumping species with such virulity. It has been known
throughout the scientific community that CDV has infected hyenas in the
park since the 1960s and both hyenas and lions have shared the same
food supplies since then.
If that were
true, why then was there a major lion epidemic of CDV in 1994 and not
earlier? One of the theories put forward by scientists was that CDV may
have always been present in big cats but that it had recently mutated
to become more virulent (New Scientist 1994, 8).
As
scientists later discovered, the CDV had mutated due to an influx of
CDV-infected dogs in the villages surrounding the park allowing for the
easy exchange of microbes between species as domesticated dogs and wild
animals intermingled.
To find out if the
virus was a mutant virus, tissue samples of 23 dead serengeti lions, 11
sick lions, and 72 apparently healthy lions were taken and sent to
several labs in the U.S. It was hoped that through extensive scientific
analysis it could be determined whether the affliction was a new strain
of CDV and how it had jumped species from dogs to cats after
historically not doing so.
After many
months of study and through the use of new genetic analysis techniques,
scientists were able to confirm that the Serengeti organism was a new
variant, or biotype, that was genetically different from normal CDV
(Morrell 1996, 596).
The new
biotype was identified in several different ways. The new ionsstrain
infected lions' hippocampus whereas other strains primarily cause an
inflation of the brain stem in dogs. It also affected dogs' bronchial
tubes but in cats, it attacked alveoli, the air sacs in the lungs
(Morrell 1996, 597). A virus that has expanded and affected new tissue
areas previously not shown to be afflicted is a sure sign of an
emerging biotype. Besides the symptoms that characterize CDV such as
grand mal seizures and recurrent twitching, scientists were able to
diagnose that the lions that had died in 1994 as also suffering from
encephalitis and pneumonia. These two diseases were usually not found
in dogs suffering from a normal CDV strain.
tanzania
lion study tour; Scientists have been able to trace environmental
changes that apparently prompted the mutation: growing human
settlements along the Serengeti National Park's western border, with
large populations of CDV-infected domestic dogs. "Human activity was
the underlying cause of the epidemic." (Schwartz 1996, 4) The Serengeti
is surrounded by a human and dog population that is growing at four
percent a year and the people in the area own roughly 30,000 dogs.
People are moving to these areas to look for work and the opportunity
to make a living. Poor soil conditions and job scarcity are often the
reasons people leave the surrounding areas to crowd around the national
parks.
Vaccination of the dogs in these
villages against CDV is rare although some dogs in the surrounding
villages had been vaccinated against distemper and rabies. Between 1993
and 1994 a CDV epidemic swept through villages to the west of the
Serengeti killing thousands of dogs. Tissue samples of lions taken
between 1990 and October 1993 showed no evidence of CDV. Of samples
taken in 1994, 63 apparently healthy serengeti lions and 8 of the 11
sick lions showed evidence of infection.
Burgeoning
human populations and their diseased animals put new and unexpected
pressures on wilderness areas - pressures that make it more likely that
dangerous microbes will move between species in the future (Schwartz
1996, 1). An exchange of diseases between species often encourages and
promotes successful mutations. Unfortunately, there are too many dogs
to inoculate against these diseases and prevent their mutation. The
dogs have an extremely high birthrate and a high population turnover so
there are lots of susceptible CDV host-animals. This kind of
environment provides an ideal condition for maintaining an epidemic.
tanzania lion study tour; Morbilliviruses have
made incredible gains in these kinds of environments and
have evolved considerably to increase their host range.
In fact, new morbilliviruses have recently been identified
in seals, dolphins, and horses and it is thought that
genetic changes may make such expansion possible. The
human population growth combined with a pool of CDV-susceptible
dogs probably lead to the new strain of the virus that
afflicted the seremgeto lions.
tanzania
lion study tour; Scientists were and still are alarmed about this
latest outbreak because the virus could come back at any time because
of the close proximity of so many non-vaccinated dogs. With the number
of dogs increasing yearly, there is a more likely chance of contact
between domestic dogs and wildlife in the future and thus a chance of
that another outbreak could occur.
tanzania
lion study tour; To help prevent this reoccurrence, veterinarians from
the Institute of Zoology in London and the Tanzanian Parks Service are
vaccinating dogs to try and get rid of some of the reservoir where the
disease could remain.
Currently, Project
Life Lion, a group local veterinary services and wildlife authorities
is traveling from village to village vaccinating dogs in hopes of
creating a cordon sanitaire around the western villages (Miller 1995,
10). Supported mainly through private donations, the vaccination
program for dogs uses First World money to protect an ecosystem of
global importance.
tanzania lion study
tour; This programme will benefit the serengeti lions and the other
cats. In 1995, forays into local villages helped vaccinate 80 percent
of the dogs in the places they visited. It is not certain, however, how
many dogs have to be vaccinated before the chain of transmission is
broken.
The veterinarians have funding
until 1999 and hope that three years of intensive vaccination will
eliminate the disease. They are also vaccinating for rabies to stop the
outbreak of that disease. Yearly vaccination in the cattle of the
villages since the 1950s to stop the spread of rinderpest (a
morbillivirus that fatally afflicts cattle) has proved successful. It
is hoped that the same kind of yearly vaccination program would work as
well for the dogs.
tanzania
lion study tour; Scientists believe that the reason the outbreak was so
severe in 1994 was because the lions were immunologically naive to CDV.
It is ironic that rinderpest in cattle has been controlled, however,
since lions may have gained immunity to CDV by eating wildebeest or
cattle infected with rinderpest (a cousin of CDV).
There
are some studies that have shown that carnivores can be protected from
CDV by exposure to rinderpest (The Economist 1994, 76). Hence, its
eradication through widespread vaccination of cattle within the past
twenty years may have left lions more vulnerable to a virulent CDV
strain this time around.
tanzania lion
study tour; Previous samples taken from 77 lions tested between 1984
and 1989 showed exposure to a virus suggesting that a similar but less
lethal epidemic occurred about a decade ago. Lions vulnerability in the
park may also be caused by the lions higher population density (3,000
individuals in 1994, an all-time high) or their resistance to disease
might have been reduced by other infections or drought.
The
large lion numbers possibly made it easier for the disease to pass from
animal to animal because there was more frequent contact.
By the time the outbreak was over several months later, approximately
1,000 lions died of CDV and all sixteen prides within the park were
affected. It was hard for scientists to get an exact figure because the
park is so large and the serengeti lions prides are generally spread
out. Combined with the fact that scavengers can reduce a carcass to
nothing overnight, it was difficult to calculate how many serengeti
lions actually died.
tanzania
lion study tour; Because of this new potent CDV strain, prospects for
endangered populations where it occurs may quickly take a turn for the
worse. CDV impact on other carnivore species is unknown. Less dense
populations of cheetahs, serengeti lions, or wild dogs are a clear
cause for concern if exposed to a virulent pathogen such as the new CDV
biotype. There was fear among Tanzanians and scientists that the CDV
strain would spread to the lions of the Ngorongoro Crater, an inbred
and isolated population of 80 individuals located just outside of the
Serengeti.
Their genetic homogeneity could
have caused them to succumb easily to the disease (Miller 1994, 5)
Fortunately, the biotype didn't spread into their areas and the lions
remained unaffected. Besides afflicting lions, the new pathogen also
killed a large number of hyenas, leopards, and bat-eared foxes. After
infecting the Serengeti, the CDV spread northwards from Tanzania to the
Maasai Mara Game Reserve in Kenya.
For
now, the threat to the serengeti lions is past. No new cases of CDV
have been reported within the last year. Survivors have developed an
immunity and the lion population has already recovered a quarter of its
losses. By August of 1994, 85 percent of the Serengeti lion population
were found to have anti-CDV antibodies (Roelke-Parker et al. 1996,
441). A number that bodes well for lions facing possible future
outbreaks.
tanzania lion study tour;
However tragic it may seem to human observers, the epidemic has simply
returned the population to its previous level since 3,000 animals was
an all- time high (Morrell 1994, 1404). The surviving lions from the
latest outbreak could teach scientists about genetic factors that made
them immune to the virulent pathogen.
The serengeti lions study shows
the reproductive cycle begins when a female enters a period of sexual
receptivity called "estrus". Males periodically sniff female
reproductive organs for signs of oncoming estrus and if these signs are
detected, they will follow a female until she is ready to mate. Females
may signal their interest in mating with elaborate tail movements and
by "walking sinuously past" a male and assuming a mating position.
During mating males often bite the female at the nape of her neck and
the act often ends with the female snarling with bared teeth at the
male.
Females remain in estrus for approximately 4
days and mating occurs several times an hour throughout the entire
period. Males actively guard estrous females from their companions, and
fights can occur if other males get too close. If females fail to
conceive they will re-enter estrus approximately two weeks later and
the cycle begins anew.
During November to mid-march the serengeti lions mating is high.
MAKE A lion study tour RESERVATION |
