The obligate intracellular pathogen Leishmania major survives and multiplies in professional phagocytes. The evasion strategy to circumvent killing by host phagocytes and establish a productive infection is poorly understood. Here we report that the virulent inoculum of Leishmania promastigotes contains a high ratio of annexin A5-binding apoptotic parasites. This subpopulation of parasites is characterized by a round body shape, a swollen kinetoplast, nuclear condensation, and a lack of multiplication and represents dying or already dead parasites. After depleting the apoptotic parasites from a virulent population, Leishmania do not survive in phagocytes in vitro and lose their disease-inducing ability in vivo . TGF-β induced by apoptotic parasites is likely to mediate the silencing of phagocytes and lead to survival of infectious Leishmania populations. The data demonstrate that apoptotic promastigotes, in an altruistic way, enable the intracellular survival of the viable parasites.

Neurocysticercosis (NCC), which is caused by infection with the larval stage of the pork tapeworm (Taenia solium), is now recognized as a major cause of neurologic diseases in countries where the infection is endemic. Migration of persons from these countries is resulting in diagnosis and local transmission in nonendemic countries at increasing rates. In the present study, immunoblotting and an ELISA were carried out using antigens of T. solium cysticerci fractionated by isoelectric focusing and serum samples from patients with NCC, alveolar (AE) or cystic echinococcosis (CE), and other diseases. Immunoblot analysis revealed antigens fractionated by isoelectric focusing (pH 9.2-9.6) either from cyst fluid of T. solium cysticerci or from intact cysts had unique components (glycoproteins) highly specific and sensitive for detection of NCC exclusively. All confirmed NCC serum samples (53 of 53) recognized at least three major bands of 10-26-kD of fractions with pH 9.2-9.6 from either intact cysts or cyst fluid. These bands were not recognized by sera from patients with other parasitic diseases including AE (0 of 34), CE (0 of 36), or other heterologous parasitoses (0 of 77), patients with hepatoma (0 of 19) or sarcoidosis (0 of 11), or sera from healthy controls (0 of 29). The ELISA using the antigens showed the same sensitivity and specificity for differentiation of NCC (53 of 53) from other diseases (0 of 107) or healthy individuals (0 of 29). Both immunoblotting and the ELISA using the fractionated antigens readily differentiated all NCC from AE or CE in a blind test of 29 serum samples of persons with NCC, CE, and AE. Antigens fractionated from cyst fluid of T. solium cysticerci by a simple, single-step isoelectric focusing (pH 9.2-9.6) are highly specific and sensitive for differential serodiagnosis of NCC in immunoblotting and/or an ELISA.

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Necropsy of 340 stray and semi-stray dogs (Canis familiaris) and nine red foxes (Vulpes vulpes) from Jordan revealed that 239 dogs (70.3%) and all foxes were infected with at least one intestinal helminth species. No trematodes were found in the intestine of these hosts. The overall infection rates with cestodes, nematodes and acanthocephalans in dogs were 66.8%, 4.4% and 2.9%, respectively. The following cestodes were identified: Echinococcus granulosus (9.4%), Taenia pisiformis (11.8%), T. hydatigena (7.4%), T. ovis (4.4%), T. multiceps (3.8%), T. taeniaeformis (2.9%), Dipylidium caninum (19.4%), Joyeuxiella (3.2%), Diplopylidium (2.4%), and Mesocestoides (0.9%). Other intestinal worms in dogs were Toxascaris (2.6%), Toxocara canis (1.2%), and Protospirura (0.6%) nematodes, and gigantorhynchiid acanthocephalans (2.9%). Intestinal helminths found in foxes included cestodes (D. caninum, Joyeuxiella, Diplopylidium, Mesocestoides), nematodes (Protospirura, Uncinaria stenocephala and Oxynema) and an acanthocephalan (Macracanthorhynchus). In both hosts, most helminths were recovered from the second intestinal segment of four equally divided segments.