we are being told at least ten people have died because of a tornado that tore through m ms. ten people, sadly among them a 3-month-old child. according to jacqui jeras it is not over yet. if it warrants it, we will break in live. see you back here tomorrow evening. be careful, thanks for watching. good night. we begin in central amp ka where a rapidly growing population are pushing people into deeper and deeper untouched forests. trying to make a living, clearing land and hunting for food. not only are they threatening fragile habitats and wiping out

animal populations at an alarming rate, they are exposing themselves to potentially harmless viruss that could spread around the world what is happening here now affects us all. rising food prices touch off riots around the world. in haiti, ten people die. in cameroon, 20 are killed. people increasingly turn to the forest for food. in cameroon, two hunters stalk their prey. their names are patrice and pate. they are searching for bush meat.

they have been out for hours but found nothing. the animals are simply gone. not too far away dr. sanjay gupta is with another hunter, but he, too, is finding his traps empty. >> it gives you an idea how hard it is to get a little bit of food. diddy, who is trying to provide enough food for nine people doesn't care what he gets as long as he gets something. we still got a long ways to go it is hot, humid, it is a lot of work. >> hunters have to keep going

deeper into forests that is where hidden danger lurks. forest animals are a reservoir of viruses, microscopic patho n pathogens living in animals' blood. >> individuals have been infected with these viruses forever. what has changed is in the past you had smaller human populations. viruses would infect them and go ekts tingts. viruses need population density. >> dr. nathan wolf is a virus hunter, he works tracking zooanatic viruses. it is these viruses that scientists think could trigger the next pandemic. >> when i look around in this forest part of what i'm thinking is what is the diversity of viruses out there. >> it may sound farfetched but it already happened, hiv is the

deadliest example. it was in a forest not too far from here in southern cameroon scientists believe hiv was born. they say it started with a chimpanzee infected with strains of viruses from eating small ir monkeys. an infected chimp's blood came in contact with a human being, a hunter or someone cutting up the chimp for cooking. that simple transmission set off a global epidemic, a pandemic that has killed tens of millions of people. scientists believe hiv crossed into humans in the early 1900s. but it wasn't until air travel increased that it spread and became a global epidemic in the 1980s. it is inevitable there will be another pandemic like a virus like hiv? >> yes. human population is going to have pandemics. we are so profoundly interconnected it will be the

case that things will enter into the human population and spread globally. >> hiv may be the most well known virus to cross over from an animal to a human but there are many others. many we don't even know about. that is why wolf has create ed what h calls a global viral forecasting initiative, a kind of early warning system in virus hot spots to track the transmission of viruses. he worked in cameroon for nearly a decade monitoring hunters and those who butcher bush meat where human and animal blood are constantly in contact. dr. wolf likens his way to an intelligence service tracking threats. if he can track what is cross into humans what he calls the viral chatter he hopes to stop the next virus before it spreads. >> each species has sort of

their own repetoire of viruses. any time humans are in contact with those animals there is the possibility for the jumpovers. that is what we are considering this chatter, this pinging, if you will, of viruses in the human population. most of the times the ping bounces back. every once in a while it sticks. >> it is sticking more often. the national academy of sciences says 75% of the world's emerging diseases jump over from animals. the sars virus crossed from civil cats in asia and killed 700,000 people in more than 20 countries. avian flu jumped other from birds around 2003 and killed more than 200 people. the origins of many others viruses are still unknown. ebola has killed hundreds over the past decade but its exact origins remain a mystery. if scientists don't know where a

disease starts it usually means it can't be stopped. it has been hours in the forest for both of teams. chasing prey that seems to vanish. we stop for a drink of water. then there's a rustle in the brush. a group of hunters approach. >> bonjour. >> bonjour. >> their packs loaded with wild game. therapy's at least three viruses that you know about wh are in there particular monkey. >> this seize, yeah. there are many, many more pathogens present in these animals. [ female announcer ] breathe right asks... [ woman ] could i ask you to strip on the street?

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dr. san yea gupta and i have split up. the two hunters we have been for the last few hours haven't found any game. we came across this group of hunters who have several packs full of animals they caught. >> this monkey potentially is infected with retroviruses. >> virus hunter nathan wolf is concerned about what viruses these animals might carry, making their way into the human population touching off a pandemic. there are at least three viruses you know about in this particular monkey? >> this seipecies. yeah. these individuals are at specific risk particularly depending on the blood contact. >> as the hunter display their kills, something surprising happens. they show us filter paper they

have used to collect the animal's blood. the blood will be tested for viruses, part of a program dr. wolf has spent years setting up. does it surprise you they are all carrying the filter paper you have been teaching them about? >> from our per spebtive it is a good indication. >> this is from this animal. these individuals, every person who has a filter paper has at least been through our basic health education about the risks associated with these activities which from our perspective gives them the ability to decrease their own risk and the risk to their families, the village the country and the world. >> once bush meat is taken out of the forest, you can find it for sale everywhere. on the side of the road there is bush meat for sale, snakes, monkeys.

and markets selling bush meats are packed with people. >> would you check the blood of these monkeys. >> absolutely. >> dr. wolf estimates 4 tons of bush meat are taken from central africa's forests every year. the bush meat trade is the single biggest threat to animal species and making mitt or a threat to humans. >> contact with an animal in a remote village that previously would have infected a few people, infected one person probably would have died out. now all of a sudden that remote village is immediately connected to the major city and through air transportation and ships to the rest of the world. something that is in the middle of nowhere, here for example can be in new york in the course of 48 hours. >> health officials aren't sure

how many humans -- >> jumped to 30 humans. >> there may be other individuals with ill animals. >> in 2003 americans were shocked when monkeypox affected dozens in the midwest. turns out it was caused by african rodents imports into america as pets. that outbreak was quickly contained. in central africa monkeypox continues to kill. dr. wolf takes sanjay and me to the democratic republic of congo where 20 people have just died from a monkeypox outbreak. we fly to a remote town where in a walled compound we find koi. alone in a small hut. >> now we're standing out here.

she is in there. why? >> we need to isolate the patient. >> are we at risk? how contagious is this? >> just looking at the patient you have no risk. but when you are in direct contact with the patient at that time you are in danger. >> koi is the latest victim. all of these people are slowly recovering and quarantined in this makeshift clinic. painful sores cover their bodies and they say they feel tired all the time. >> if she hadn't made it to you, to this place, what would happen to her? >> some patients recover, but others die. >> koi probably got monkeybox through contact with bush meat which she said she handled over the past few weeks or came in contact with an infected person.

its exact origins are still unknown. it is unlikely mop ki pox could become a pandemic because it loses strength as it passes from person to person, unlike hiv. koi will have to stay quarantined for weeks. there is little the medical team can doerr than hoping she survives. her case is a warning and a sign of things to come. >> we are just tapping the surface. the tip of the iceberg when it comes to the knowledge of the viruses out there. documenting them potentially to get to a space to prevent pandemics instead of waiting for aids to spread globally could potential slave millions of lives. >> great white sharks are the most feared animals on the planet. there is a lot we don't know

about them. some people believe you need to get in the water with them. it is a controversial idea. critics say that enkoocourages sharks to attack humans. we decided to get in the water for ourselves and find out. when great white sharks start to circle your boat, the feeling is unsettling. 15 feet long, thousands of pounds. these are the animals of so many nightmares. >> this is a famous shark, elly. >> we've come to dive with these great whites to get an up-close look at them and the battle being waged around them.

mike takes tourists kamg diving with great white sharks off the coast of south africa. it has become a big business but it's also, he says, a conservation effort. if people can see these endangered animals underwater they will learn to appreciate them and want to protect them. cage diving is highly controversial. we'll tell you why in a second. right now the water is filled with blood and fish parts called chum and the great whites have arrived. is there any recommendations for what to do? >> well, basically don't scare the sharks. >> i'm not worried about scaring the sharks. after we get used to being in the water with the sharks inside a cage, we have the chance to do something few others ever have. we'll go swimming with great white sharks without a cage.

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and save 50% on pads and shoes. meineke. >> oh! >> climbing into a shark cage is scary. the sea is chummed with blood and fish parts and underwater visibility is low. first all you see is a vague shape moving fast. then all of a sudden you find yourself face-to-face with a great white shark. its mouth open, its eyes rolling back into its head. one thing to see a great white shark from the boat. but to be down in the water, to be, you know, six, seven feet away from one, it is an extraordinary experience.

this experience has become a major draw for tourists. each one of these people paid $150 to visit this reef off the coast of south africa known as shark alley. >> that is a great white shark. >> it is one of the best places in the world to see great whites and shark tourists bring in $30 million every year to south africa. is this really good for sharks? the battlelines are drawn. at issue is how the sharks are brought to boat. chumming, mashed up fish parts and blood are thrown into the water and the scent attracts the great whites. once the sharks arrive a tuna head attached to a rope is used as bait to get the sharks to lunge at the cave. >> the bite is a visual reference to the smell. we don't let it take the bait.

we are trying to full the bait so the animal can come closer to the cage that the people can see a bit better. >> but it does sometimes get the bait? >> it does sometimes get the bait which is unfortunate. >> critics say it is more than unfortunate. it is dangerous. it teaches them to associate food with humans in the water. that some people is encouraging great whites to eat swimmers and surfers. craig bovem thinks cage diving could be why a great white almost killed him. he was diving for lobster on this beach near capetown in 2005 when he was attacked. >> they just clamped on both my arms. when i came out of that impact i was still inside his mouth and he was slowly swimming with me. >> the shark was dragging him

out to sea. after he overcame the shock, he began to fight back. >> so i started putting my knees into his belly. i saw that was having some effect on him. i head butted him with my mask on his nose. carried on this tussle. >> basically you are wrestling with a shark underwater? >> yeah. i wasn't getting up. pi pulled on my right han. i pulled and eventually my arm came free. >> so this bite is your -- >> yeah. >> both of his hands were mange ld and his right one is permanently damaged. he still surfs and dives but he has become one of cage diving and chumming most vocal critics. >> you cannot find a single kpachl of people feeding and attracting and baiting animals that is successful. it is a no-no.

>> with no other animal viewing do people bait or chum? >> nobody would think about doing that. >> shark tour operators can't do it anymore in florida and hawaii after a series of vicious shark attacks chumming was banned in both states. but shark tour operators in south africa point out even though shark tourism has risen dramatically in the past decade, shark attacks have not. on average five attacks on humans every year in south africa. craig and others insist the behavior of sharks is changing. normally if a shark bites a human, they release them. the shark that attacked him did not n. the last four years there have been at least two deadly attacks in which sharks ate their victims whole. so who is right? unfortunately, the science to support either position isn't easy to come by.

for all our fear and fascination of great whites, they remain a mystery. there is so much we simply don't know about their behavior. they've never been seen mating or giving birth. they are classified as an endangered species, we don't know how many of them there are. allison is a marine biologist studying the effects of cage diving on great whites. she is tagging them to track the shark's movements around these waters for mont. >> here we go. keep it there. keep it there. tagged. >> she has tagged over 70 sharks so far. the data she collected led to the only peer reviewed study on cage diving on shark behavior. >> the study we did showed a surprising result, sharks stopped responding over time to

the boats. >> you don't see any connection between increased shark attacks and shark tourism? >> no. not at all. all the evidence we have at the moment finds no link between chumming and shark attacks. we are definitely not on the shark's menu. >> mike stiks his life on it. he is one of the few people willing to swim with great white sharks without a cage. he has been doing it for ten years. he believes to understand their true nature you have to do it without a cage, meet the animal on its own terms. we decided to join him underwater so we, too, can come face-to-face with this feared predator of the sea without a cage. ♪

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i'm don lemon. we are tracking this deadly weather throughout the south. theus ten people have been killed in mississippi, the youngest just 3 months old. the storm threat will last into sunday in alabama, kentucky, mississippi and north georgia there are dozens of unconfirmed reports of tornadoes through northern missouri and mississippi. the most destructive hit yazoo city, mississippi, where three

people died. this thing was massive and it blew to pieces homes, businesses, churches, anything it came across. rescuers are searching for more in the rubble. emergency officials expect, sadly, the death toll to rise. keep it tuned here to cnn. those are your headlines this hour. i'm don lemon. keeping you informed. cnn, the most trusted name in news. ♪ [ male announcer ] let's kick our excuses to the curb. cover 'em up with an extra bag of mulch. let's get our hands a little busier. our dollars a little stronger. and our thinking a little greener. let's grab all the bags all the plants and all the latest tools out there. so we can turn all these savings into more colorful shades of doing.

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preparing to swim with great white sharks without a cage produces two reactions. the first is, well, fear. it is hard to believe you are about to actually do this. the second reaction is a surge of adrenaline. >> definitely gets your heart beating. >> mike knows that better than anyone. he's dived with great whites without a cage hundreds of times. he once caught a ride on a great white's dorsal fin. he insists these animals may be top predators, but they are not the man eating machines so often portrayed in movies. we decided to take him up on his offer to dive without a cage and see the great whites in their natural state. what do we need know? >> don't make fast movements. as long as the jackal behaves he doesn't get killed.

>> we are tjackals and they are the lions. >> don't try to grab a bone and run away. >> the water is filled with chum, fish parts and blood. a number of sharks are already circling the boat so it is time to go. to get to the bottom i climb into a cage which is lowered about 20 feet to the ocean floor. mike's already there scouting for any sharks. then he signals for me to swim out. almost immediately my weight belt falls off. struggling with that is the last thing you want to do around great whites. the current is really strong. mike has me hold on to a rock to stay in place. visibility is low. but then suddenly the sharks

come into view. it's clear they see us but they're keeping their distance, gliding by slowly, gracefully. it is remarkable to see them like this, to be so exposed to an animal that is so feared. mike warned me they don't like the sound of air bubbles and told me to hold my breath. truth is my heart is pounding so fast holding my breath is almost impossible. at one point there are four different sharks swimming around us. it's important to stay alert but after a while i'm also able to appreciate the beauty, the power of these animals. widely hunted, universedly despised, capable of such destruction, but when you see them like this, not lunging

after bait, but simply gliding through the water you see them in a different way. you understand there is more to them than you know. we stay down for nearly 30 minutes until our oxygen nearly runs out. to see it so close, i have never seen anything like it. it was amazing. >> not man killers. >> that was great. thank you. that was pretty amazing. you get a totally different sense seeing them like that versus seeing them in the cage where they are attacking a piece of bait. >> they're just trying to be sharks. >> the truth is we really don't know enough about what that means slopgs our knowledge of sharks is dwarfed by fear and hatred of them the fight over their future will go on.

#. >> next on "planet in peril" mountain gorillas. >> we have been hiking for nearly two hours. we're not sure how much farther up the gorillas are. >> how the animals and a country helped bring each other back from the brink. what are you ? a shiny coat of paint? a list of features? what about the strength of the steel? the integrity of its design... or how it responds... in extreme situations? the deeper you look, the more you see the real differences. and the more you understand what it means to own a mercedes-benz. the c-class. see your authorized mercedes-benz dealer for exceptional offers through mercedes-benz financial. ♪ and she said hair was growing back... i was like, yes, this works... [ male announcer ] only rogaine is proven to regrow hair in 85% of guys.

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the list of threats to our planet are almost too many to count, species lost, habitat

destructi destruction, climate change. there are surfing stories like in rwanda where the gorillas are thriving and bringing hope to an entire country. you hear them before you see them. snapping branchs, deep grunts. they are the world's last remaining moup tan gorillas. massive and magnificent, they are cautious but incredibly curious. there are only about 720 of them left on the planet, all of them living in the forest that stradles rwanda, uganda and the democratic republic of congo. they are critically endangered, on the brink of extinction. but in rwanda, the survival of the gorillas is a case study how a country benefits from

protecting its natural resources instead of destroying them. it is a success story in one of the most unlikely places on earth. just 14 years ago ra wapda was in chaos. as one ethnic group tried to exterminate another. neighbors killed neighbors. it was a genocidal blood bath resulting in the deaths of nearly 1 million people. since then rwanda has emerged from the violence and looked for ways to rebuild, looked for signs of hope. they found it in the forest. they found it in the gorillas. why was it important for you to come back here after the genocide? >> to come to see the animals, the gorillas.

>> there were still armed militia roving when a park ranger and guide risked his life to check on the gorillas just after the genocide in 1994. he took us to the spot where he entered rwanda's volcanos national park during those dangerous days. >> i have one group of 13. i visited the first time. the silverback die because of the problem the people killed the silverback. >> during the genocide. what is that like to see one of the gorillas dead? >> oh, it is a problem. it was sad. it is same as your children. if your children die or your wife die you are sad. >> seeing a gorilla die is like seeing a member of your family die. >> for me is.

the problem for the gorillas for decades were they were hunted and sold to zoos or killed as trophies. local poachers set snares for other animals the gorillas got caught in. after the genocide ended a new government took over and they decided to get serious about protecting the mountain gorillas. essentially they gambled they could pull the country and a species back from the brink simultaneo simultaneously. they decided to put the gorillas at the center of their tourism effort. to regular rwandans it was a tough sell. thed of parks and tourism. >> the community was antagonistic. they didn't understand and you can't blame them. why should they protect the gorillas? what does it mean to snem. >> no one seems to ask that question anymore.

in 2007 more than 13,000 tourists paid up to $500 to spend one hour with some of the gorilla families ha pitch waited to humans by scientists. tourism is now the country's third largest generator of foreign capital. 5% of the $7 million the government earned last year from gorilla tourism went back to the communities near the gorillas' habitat. it is used to build roads, schools and health clinics. local people now see a benefit to keeping the gorillas alive and rwanda the animals themselves are thriving. next door, however, it's another story. about half of the world's last remaining mountain gorillas live in forests in the democratic

republic of congo. just last year ten gorillas there were slaughtered. shot to debt. some were even set on fire. congo has been battered by civil war for more than a decade now and some 5 million people have died as a result. the gorillas' habitat is literally a battleground. so unstable rangers can't enter the forest to patrol and protect them. there's nine gorillas in this group. during a lull in the fighting we visited congress ee's gorillas in 2006. today no one is sure these same gorillas are even alive. that uncertainty makes the protection of rwanda's gorillas all the more important. veronica has been monitoring

rwanda's gorilla groups as director of research for the diane fossey foundation. a research group, gorillas never visited by tourists. the scientists say there is a lot of aggression in the group and not really sure how they'll react to our presence. so frankly if they charge, i'm going to hide behind the biggest cameraman we can find. >> those are fresh tracks. your p.a.d. isn't just poor circulation in your legs causing you pain. ok. what is it? dad, it more than doubles your risk of a heart attack or stroke. you'd better read about plavix. if you have p.a.d., plavix can help protect you from a heart attack or stroke. plavix helps keep blood platelets from sticking together and forming clots- the cause of most heart attacks and strokes. talk with your doctor about plavix?

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deep in rwanda's volcanoes national park we're hiking high into the mountains to see an animal threatened by conflict on the brink of extinction. >> we've been hiking two hours. we're heading to a group of mountain gorillas which have never been visited before by tourists. they're not habituated in the same way. they've only been studied by scientists. >> he doesn't like people. >> before we entered the park veronica the biologist was telling us there's a lot of aggression in this group we're going to be visiting. it should be interesting. gorillas are always on the move. searching for food and a place to rest. trackers have gone up ahead of us to locate the family and radio us the coordinates. but even with the extra help, finding them isn't easy.

nearly three hours into the hike, there are signs we're finally getting close. >> those are fresh tracks. >> we finally find them in a large clearing and come face-to-face with one of the family's blackbacks, a young male. our trackers grunt, signaling we're not a threat, and he lets us go by. it's an amazing sight, 43 gorillas in this single spot in the forest. about 20% of rwanda's entire gorilla population.

this family is called the pablo group, named after the male silverback who used to be in charge. pablo is still around, but another silverback, kansbey, is now the boss. >> that's the silverback. that's the adult male? >> that's the adult male silverback. >> an adult male can weigh about 400 pounds and eats up to 60 pounds of vegetation a day. >> she transferred for one of the tourist group. >> a biologist and director of data and research for the diane fossey foundation, veronica vacelio studies the three research groups. what's the value of having a group that's not a tourist group that's just a research group? >> continuing the research in gorillas is always important. always give a lot of information in terms of population dynamics. >> population dynamics are important, especially since there are only about 720 mountain mountain gorillas left in the wild.

and they're smack dab in one of the world's worst conflict zones. even the gorillas seem to know it. you have the congo border, and there's obviously so much instability in congo. how does that impact the gorillas? >> the gorilla, they are pretty much obliged to stay in rwanda. they try several time to move and to cross the border, and after a few hours they run away. literally, they run away and come back to rwanda. >> we've been here for about an hour, and kansbey and the others don't seem to mind our presence. frankly, they seem a little bored with us. >> we've been warned these gorillas might be aggressive because there are so many adult males in the group. veronica tells us it's been

raining so much at night and it's been particularly cold so a lot of these mountain gorillas are exhausted and they're just kind of sleeping through the day. because gorillas can catch human diseases, scientists limit the time they spend with them. so after only an hour and a half, it's time for us to go. what we're doing is going around the world looking at places where man is in conflict with nature and natural resources in animals. it seems like rwanda is a success story in many ways. >> yeah, yeah. definitely it is. there's still a lot of conflict, but there's a lot of rwanda that they really care of the protection of gorillas and this is i think the most beautiful success of conservation of mountain gorillas, just to have the local people to take care of their own natural resources. >> this is a species still teetering on the brink. but rwanda's protection of these

mountain gorillas is a lesson that conservation is possible. even on the battle lines. over the next 40 years the human population is expected to rise by 50%. already many of our natural resources are dwindling. recently, the u.s. director of national intelligence said over roughly the next decade competition for those resources will likely lead to increased global conflict. the question governments around the world have to answer now is how best to preserve the resources we have left through conservation, innovation, and technology. if you want more information, go to cnn.com/planetinperil. i'm anderson cooper. thanks for watching this earth day special of "planet in peril." [ female announcer ] sometimes you need tomorrow

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