Fatal Toxoplasmosis in Free-Ranging Endangered ‘Alala From Hawaii

Abstract

The 'Alala (Corvus hawaiiensis) is the most endangered corvid in the world, and intensive efforts are being made to reintroduce it to its former native range in Hawaii. We diagnosed Toxoplasma gondii infection in five free-ranging 'Alala. One 'Alala, recaptured from the wild because it was underweight and depressed, was treated with diclazuril (10 mg/kg) orally for 10 days. Antibodies were measured before and after treatment by the modified agglutination test (MAT) using whole T. gondii tachyzoites fixed in formalin and mercaptoethanol. The MAT titer decreased four-fold from an initial titer of 1:1,600 with remarkable improvement in physical condition. Lesions of toxoplasmosis also were seen in two partially scavenged carcasses and in a third fresh intact carcass. Toxoplasma gondii was confirmed immunohistochemically by using anti-T. gondii specific serum. The organism was also cultured by bioassay in mice from tissues of one of these birds and the brain of a fifth 'Alala that did not exhibit lesions. The life cycle of the parasite was experimentally completed in cats. This is the first record of toxoplasmosis in 'Alala, and the parasite appears to pose a significant threat and management challenge to reintroduction programs for 'Alala in Hawaii.

Avian Botulism: A Case Study in Translocated Endangered Laysan Ducks (Anas Laysanensis) on Midway Atoll

“…Three of 84 Laysan Ducks had mild infections with proventricular nematodes (suspected Echinuria sp.) characterized by presence of cross sections of nematodes within the lumen of proventricular glands occasionally associated with mild to moderate amounts of eosinophilic cellular debris (Work et al, 2004). One pintail also had a mild infestation of proventricular nematodes with little to no inflammatory response.…”

“…can cause significant disease, particularly in birds experiencing crowding stress (Ould and Welch, 1980), such as during drought, when birds are concentrated around freshwater sources, presumably enhancing chances of exposure and infection (Cornwell, 1963). On Laysan, low rainfall, poor food resources, and crowding around limited freshwater seeps were believed to be contributory factors (Work et al, 2004). The epidemic was catastrophic and resulted in a population decline of nearly 75% (Reynolds, 2002).…”

“…In August-October 1993, an epidemic of emaciation complicated by infection with the nematode Echinuria uncinata (Echinuriasis) was detected in Laysan Ducks from Laysan Island (Work et al, 2004). Echinuria spp.…”

“…Because diseases can have a disproportionate demographic effect, particularly for isolated, endangered species (Thorne and Williams, 1988;Work et al, 2000), risk assessments for disease should be an inherent part of any wildlife translocation plan and should include measures to minimize the risk of moving pathogens. This includes developing a well-known health history of the source and destination wildlife populations through necropsy surveys, quarantine, clinical examinations, vaccination, and management protocols for animals at the release site (Viggers et al, 1993).…”

Survival of Feral Cats,Felis catus(Carnivora: Felidae), on Mauna Kea, Hawai'i, Based on Tooth Cementum Lines

“…Feral cats in Hawai'i prey upon endangered forest birds (Laut et al 2003, Hess et al 2004) and terrestrial birds that nest near the ground (Kowalsky et al 2002), as well as colonial nesting seabirds (Hu et al 2001, Smith et al 2002). In addition, cats are the definitive host of Toxoplasma gondii, a parasite that has killed individuals of several native and introduced wildlife species (Work et al 2000, Honnold et al 2005. Feral cats range throughout the Hawaiian Islands from high-density colonies near coastal areas where pets are frequently abandoned and fed by people (Winter 2003), to remote, lowdensity populations in montane forests and subalpine areas of Maui (Simons 1983) and Hawai'i Island (Tomich 1986, Hu et al 2001).…”