Nematodes are roundworms characterized by a tough outer cuticle, unsegmented bodies, and a fully developed gastrointestinal tract. The order Strongylida includes hookworms and lungworms. Metastrongyloidea are characterized as 2-cm-long, slender, threadlike worms that reside in the lungs of the definitive host. Angiostrongylus costaricensis is a closely related worm that causes intestinal angiostrongyliasis in Central and South America. Epidemiology and pathogenesis
Following World War II, A. cantonensis spread throughout Southeast Asia and Western Pacific Islands, including Australia, Melanesia, Micronesia, and Polynesia. Cases were soon reported in New Caledonia, the Philippines, Rarotonga, Saipan, Sumatra, Taiwan, and Tahiti. In the 1960s, even more cases were reported from the region from locations such as Cambodia, Guam, Hawaii, Java, Thailand, Sarawak, Vietnam, and Vanuatu.In 1961, an epidemiological study of eosinophilic meningitis in humans was conducted by Rosen, Laigret, and Bories, who hypothesized that the parasite causing these infections was carried by fish. However, Alicata noted that raw fish was consumed by large numbers of people in Hawaii without apparent consequences, and patients presenting with meningitis symptoms had a history of eating raw snails or prawns in the weeks before presenting with symptoms. This observation, along with epidemiology and autopsy of infected brains, confirmed A. cantonensis infection in humans as the cause of the majority of eosinophilic meningitis cases in Southeast Asia and the Pacific Islands.Since then, cases of A. cantonensis infestations have appeared in American Samoa, Australia, Hong Kong, Bombay, Fiji, Hawaii, Honshu, India, Kyushu, New Britain, Okinawa, Ryukyu Islands, Western Samoa, and most recently mainland China.
Similarly, in a periodontal abscess pus most likely discharges via the periodontal pocket, whereas a periapical abscess generally drains via a parulis nearer to the apex of the involved tooth. If the tooth has pre-existing periodontal disease, with pockets and loss of alveolar bone height, it is more likely to be a periodontal abscess; whereas if the tooth has relatively healthy periodontal condition, it is more likely to be a periapical abscess. In periodontal abscesses, the swelling usually precedes the pain, and in periapical abscesses, the pain usually precedes the swelling. A history of toothache with sensitivity to hot and cold suggests previous pulpitis, and indicates that a periapical abscess is more likely. If the tooth gives normal results on pulp sensibility testing, is free of dental caries and has no large restorations; it is more likely to be a periodontal abscess. A dental radiograph is of little help in the early stages of a dental abscess, but later usually the position of the abscess, and hence indication of endodontal/periodontal etiology can be determined. If there is a sinus, a gutta percha point is sometimes inserted before the x-ray in the hope that it will point to the origin of the infection. Generally, periodontal abscesses will be more tender to lateral percussion than to vertical, and periapical abscesses will be more tender to apical percussion. Treatment
Successful treatment of a dental abscess centers on the reduction and elimination of the offending organisms.