Visceral pentastomiasis in humans is caused by the larval stages (nymphs) of the arthropod-related tongue worms Linguatula serrata, Armillifer armillatus, A. moniliformis, A. grandis, and Porocephalus crotali. The majority of cases has been reported from Africa, Malaysia, and the Middle East, where visceral pentastomiasis may be an incidental finding in autopsies, and less often from China and Latin America. In Europe and North America, the disease is only rarely encountered in immigrants and long-term travelers, and the parasitic lesions may be confused with malignancies, leading to a delay in the correct diagnosis. Since clinical symptoms are variable and serological tests are not readily available, the diagnosis often relies on histopathological examinations. This laboratory symposium focuses on the diagnosis of this unusual parasitic disease and presents its risk factors and epidemiology.
The pathogenesis of chronic parasitic central nervous system (CNS) infections, including granulomatous amoebic meningoencephalitis (GAE), cerebral toxoplasmosis (CT), and neurocysticercosis (NCC), is primarily due to an inflammatory host reaction to the parasite. Inflammatory cytokines produced by invading T cells, monocytes, and CNS resident cells lead to neuroinflammation which underlie the immunopathology of these infections. Immune molecules, especially cytokines, can therefore emerge as potential biomarker(s) of CNS parasitic infections. In this study, cerebral spinal fluid (CSF) samples from suspected patients with parasitic infections were screened for pathogenic free-living amoebae by culture (n=2506) and PCR (n=275). Six proinflammatory cytokines in smear and culture-negative CSF samples from patients with GAE (n = 2), NCC (n = 7), and CT (n = 23) as well as control (n = 7) patients were measured using the Multiplex Suspension assay. None of the CSF samples tested was positive for neurotropic free-living amoebae by culture and only two samples showed Acanthamoeba 18S rRNA by PCR. Of the six cytokines measured, only IL-6 and IL-8 were significantly increased in all three infection groups compared to the control group. In addition, TNFa levels were higher in the GAE and NCC groups and IL-17 in the GAE group compared to controls. The levels of IL-1b and IFNg were very low in all the infection groups and the control group. There was a correlation between CSF cellularity and increased levels of IL-6, IL-8, and TNFa in 11 patients. Thus, quantifying inflammatory cytokine levels in CSF might help with understanding the level of neuroinflammation in patients with neurotropic parasitic diseases. Further studies with clinico-microbiological correlation in the form of reduction of cytokine levels with treatment and the correlation with neurological deficits are needed.
The occurrence of macroparasites was studied from 543 stray cats in four urban cities from the west (Kuala Lumpur), east (Kuantan), north (Georgetown) and south (Malacca) of Peninsular Malaysia from May 2007 to August 2010. Five ectoparasites species were recovered namely, Ctenocephalides felis, Felicola subrostratus, Haemaphysalis bispinosa, Heterodoxus spiniger and Lynxacarus radovskyi. Two cats from Georgetown were infested with the dog louse, H. spiniger and this represented the first host record for this species in Malaysia. Up to nine species of helminths were recovered with overall high prevalences of infection of 83% in Kuantan, followed by 75.1% in Kuala Lumpur, 71.6% in Georgetown and 68% in Malacca. The helminth species comprised five nematodes, Toxocara malaysiensis, Toxocara cati, Ancylostoma braziliensis, Ancylostoma ceylanicum, Physaloptera praeputialis, two cestodes Taenia taeniaeformis, Dipylidium caninum and one trematode, Playtnosomum fastosum. The majority of helminths were present in the four study sites except for the absence of P. praeputialis in Kuala Lumpur. The prevalence and abundance of infections were analysed taking intrinsic (host age and sex) and extrinsic (season) factors into consideration. Levels of infection and infestation were mainly influenced by host age and to a lesser extent sex and season, whereas four nematode species exhibited significant interactions within the intestine of the cat host. The potential for transmission of some macroparasite species from stray cats to the human population in urban areas is discussed.