Raschel knit polyester, unknown plastic debris, and ice cream and sanitary product wrappers. A study at the University of Miami in Florida assessed 439 manatee carcasses that were recovered and necropsied between 1978 and 1986. Of these, 63 (14.4%) had ingested debris; 4 of the animals died as a direct result of ingestion of plastic or other debris. Some of the debris that was found in the animals' GI tracts included monofilament fishing line (the most common item found), plastic bags, string, twine, rope, fishhooks, wire, paper, cellophane, synthetic sponges, rubber bands and stockings. Infectious diseases may also play an important role in morbidity and mortality. Although viruses have been identified only from Florida manatees, parasites and bacteria have been observed in at least three of the four sirenian species. The viruses that have been detected in Florida manatees include trichechid herpesvirus 1 (TrHV-1) and manatee papillomaviruses (TmPV) 1 through 4. Mycobacteriosis has reportedly led to mortality in captive Florida manatees and illness in Amazonian manatees while bacteria such as Vibrio, Pasteurella, Pseudomonas, Streptococcus, and Clostridium have been cultured from dead dugongs in Australia. Salmonellosis has been associated with mortality in dugongs since at least 1981. Although not well studied, the Senegal manatee is known to host the nematode Heterocheilus tunicatus, just as its sister species the West Indian manatee does. There is still a great deal to learn about the threat that infectious diseases pose to both wild and captive populations of manatees. The relationship between the presence of certain potential pathogens, including those listed above, and their effect on disease in individuals is still largely unknown, although many wild manatees are found to be positive for papillomavirus with no known negative health effects. Immunosuppressed individuals that test positive for papillomavirus can sometimes develop cutaneous lesions; however, cutaneous papillomatosis is not always correlated with a papillomavirus infection, and further study is warranted. In Florida, agricultural runoff can negatively affect the manatee habitat, and during the rainy season, over 50 counties practice fertilizer bans to try to limit the pollutants that end up in waterways. Weather disasters and other natural occurrences are also sources of mortality. The West Indian manatee and dugong face risks from hurricanes and cyclones, which are predicted to increase in the future. These storms can spread pollutants and may damage seagrass populations. African manatees can become stranded during the dry season when rivers and lakes become