Three years ago, Dr. Greg Bossart, VMD, Ph.D. Director of Harbor Branch Oceanographic Institution's (HBOI) Division of Marine Mammal Research and Conservation and colleagues from the University of Miami School of Medicine described the first viral disease in manatees.

In what is the first step in a long-term study of the papillomavirus in manatees, scientists from HBOI are working with staff at Homosassa Springs State Wildlife Park on a series of medical tests on Florida manatees. Manatees like "Holly", "Loreli" and "Betsy," "Ariel" and her calf "Amanda," will be the subject of important investigations by reseachers to help ensure the survival and recovery of this species.

On the Verge of Extinction
The Florida manatee (Trichechus manatus latirostris) is one of the most endangered marine mammals in the world. The long-term survival of the species is in jeopardy. Among the chief threats to manatee survival are the collisions with watercraft that occur all too frequently in Florida waters, and the continued loss of suitable habitat to degradation and development. Brevetoxicosis, a deadly condition caused by the microorganism responsible for Florida red tide has also been linked to a large number of manatee deaths in west coast Florida manatee populations in recent years. In 1996, 150 manatees in southwestern Florida died from the effects of red tide. This devastating event represents the largest die-off of an endangered species ever recorded.

Natural mortality due to infectious disease, on the other hand, is a relatively rare occurrence in manatees. In truth, there seem to be very few natural pathogens capable of causing disease in healthy manatee populations.

Which is all the more reason a small population of captive manatees from a rehabilitation center at Homosassa Springs State Wildlife Park have researchers perplexed. And worried. Seven of the nine female manatees in this small group are exhibiting signs of infection by a virus that causes tumorous skin lesions and growths known as cutaneous papillomas. The other two animals are likely to be subclinically infected - harboring the viral agent but as yet remaining free of symptoms.

Since the tumors were first discovered, the infection has spread quickly throughout the small Homosassa manatee population. The tumors are generally limited to the lips, nostrils, and leading edges of the pectoral flippers, reinforcing the belief that the virus is readily transmitted through contact between infected and non-infected individuals. The papillomas are benign, but they have the potential to become life threatening if they grow to the point where they begin to interfere with feeding, sight, or breathing. Furthermore, similar tumors caused by papillomaviruse in other mammalian species (over a 100 types have been reported in humans, including one known to be a cause of cervical cancer in women) have been proven capable of undergoing spontaneous malignant transformations. It is feared that the manatee virus might be capable of doing the same.

A New Manatee Care Facility Will House Infected Animals
The Division of Marine Mammal Research and Conservation is seeking a permit from the U.S. Fish and Wildlife Service to transfer the entire captive Homosassa population temporarily to Harbor Branch for study, care, and treatment. If the permit is granted, a number of positive outcomes directly benefiting the endangered Florida manatee population are expected.

First, there is a possibility that once the novel viral agent is described and the mechanics of the disease are defined, the infected animals can be cured. Their apparently compromised 'super' immune systems can hopefully be stimulated to the point that remission occurs (interestingly, the manatee immune system may be unmatched in the vertebrate world, partially explaining the rarity of natural disease occurrence). Dr. Bossart points out that the virus discovered in these manatees belongs to the same family of viruses that cause cervical cancer in humans. Alfred Bennett Jenson, M.D., a cervical cancer expert collaborating with Dr. Bossart, feels this opportunity will help in the development of vaccines which will attack the human infecting strain.

Additionally, the facilities at Homosassa Springs State Wildlife Park can be certified virus free so that it may again operate as one of only three designated manatee secondary recovery facilities (Mote Marine Laboratory in Sarasota and Epcot Living Seas are the other two). The secondary recovery facilities are operated as "soft release" facilities as part of a statewide, multi-agency manatee rescue and rehabilitation program. Rescued manatees well on the road to recovery are relocated to these facilities from one of three designated critical care facilities (Miami Seaquarium, Sea World of Florida, and Lowry Park Zoo in Tampa) for final rehabilitation and care prior to release back to the wild. Since the discovery of the papillomavirus infection in the captive Homosassa population, the facility has been under quarantine and the statewide rehabilitation severely logistically hobbled.

Most importantly, this will help insure against transmission of the infectious agent to adjacent free-ranging manatee populations. The captive manatees are housed in a penned area at the headwaters of Homosassa River. Wild manatees winter in large numbers in areas just downstream of the captive facility. Therefore, a potential exists for the natural transmission of papillomavirus from infected captive animals to the wild population.

Manatees Need Your Help
In 2000, 273 Florida manatees died. Recent scientific evidence indicates that the manatee will slowly decline to extinction if this pattern is not reversed. The Florida manatee is running out of time. Help ensure its survival by contributing to HBOI research, conservation, and rescue efforts for this magnificent, gentle giant.

The Division of Marine Mammal Research and Conservation has begun fund rasing efforts to construct a new, state-of-the-art 600,000-gallon manatee rehabilitation facility to house the temporarily transplanted animals. We hope to complete the facility by the end of the year. Your tax deductable contribution will go a long way in helping Dr. Bossart and his team learn more about this threatening virus and possibly develop a cure to safeguard the endangered West Indian manatee from extinction.

Homosassa Footage - 02.22.01 • Manatee Feeding Footage - Quicktime

Homosassa Footage - 02.22.01 • Ariel's Medexam - Quicktime

Homosassa Footage - 02.22.01 • Holly's Medexam - Quicktime