Abdominal Ascariasis: Where to Focus on Imaging Studies

Objective: To assess the various presentations of abdominal ascariasis and their imaging features for developing a comprehensive radiological evaluation protocol. Methods: Demographic and clinical profile of 84 patients with abdominal ascariasis was noted. Patients were divided into 2 groups with age less than 20 comprising Group A and those with age greater than 20 Group B. All the patients had a routine lab workup and a dedicated USG scan to look for objective evidence of intestinal or hepatobiliary ascariasis. Any history of previous intervention (cholecystectomy or ERCP) was also sought. Results: Abdominal ascariasis is more common in females observed in 62% of our patients. Peripheral eosinophilia was observed in 70 (83%) patients. We had 74 (88%) patients with intestinal ascariasis with 2 patients having appendicular ascariasis. Biliary ascariasis was observed in 20 (24%) patients and pancreatic ductal ascariasis in 6 (7%) patients. We found peritoneal ascariasis in 1 (2%) pediatric patient and 2 (3%) patients in our study had ascariasis associated with the liver abscess. OCH was observed in 4 patients while 2 patients presented with worm cholecystitis. Conclusion: Peripheral eosinophilia can be used to select patients in endemic regions for undergoing a dedicated USG scan. USG is the investigation of choice for both intestinal and hepatobiliary ascariasis. Worm migration is more common in adults and is especially prevalent in individuals with previous history of ERCP or cholecystectomy.

The relationship between microfilaraemic and amicrofilaraemic loiasis involving co-infection with Mansonella perstans and clinical symptoms in an exposed population from Gabon

The relationship between the frequency of loiasis objective symptoms and microfilaraemic or amicrofilaraemic infection was assessed in 1148 exposed patients also infected, or not, with Mansonella perstans. Filarial infections were detected by direct microscopy, leucoconcentration and serology, with prevalence values of 39.5% Loa loa, 5.6% M. perstans and 3.4% co-infection with both filarial species. Amicrofilaraemic or occult loiasis (OL) predominated among L. loa-infected individuals, with a prevalence of 58.2%. Hypermicrofilaraemia (>8000 microfilariae (mf)/ml) was found in 18.4% of L. loa microfilaraemic patients, with 25.7% of them harbouring more than 30,000 mf/ml. Up to 34% of patients with OL showed evidence of Calabar swelling, compared with 26.3% of microfilaraemic patients (P= 0.03). Overall 5.3% of patients presented with adult worm migration across the eye, representing 16.3% of microfilaraemic individuals and 11.4% of amicrofilaraemic patients (P= 0.13). This symptom was similarly found in patients with more than 30,000 mf/ml (22%), those with microfilaraemia between 8 and 30,000 mf/ml (15.4%) and also in individuals with low or without microfilaraemia (16.1%) (P= 0.7). Five (14.3%) hypermicrofilaraemic patients did not present any L. loa-specific objective symptoms, as well as all the patients with single M. perstans infection. The presence of adult eye worm migration as a strong predictor of high microfilaraemia density would obscure the real burden of L. loa hypermicrofilaraemia in exposed individuals. For epidemiological purposes and control strategies, the mapping of L. loa in endemic areas should also take into account the group of patients with occult loiasis.

Study on migration modes and correlative factors of Tubifex tubifex (Oligochaeta, Tubificidae) in source water

Excessive propagation of tubificid in eutrophic source water can result in its emergence in the drinking water plant, which has been a troublesome problem in recent years. The migration of tubificid, especially drift migration in the source water is the main cause of worm pollution in drinking water plant. Migration modes and correlative factors of Tubifex tubifex, dominating the tubificid frequently, were investigated to help drinking water plant to solve worm pollution. Migration modes were divided into superficial, deep and drift migrations, representing migrations occurring in surface sediment (0–2 cm), deep sediment (deeper than 2 cm) and from sediment to overlying water, respectively. The results showed that both temperature and dissolved oxygen (DO) affect the worm migration modes. The maximum drift efficiency occurred at 22°C while DO was controlled around 8 mg O2 l−1. When the temperature was fixed at 20°C, maximum drift efficiency was observed at 2 mg O2 l−1. Distinct increase of superficial migration and decrease of deep migration were observed at 28°C compared to 16 and 22°C. Low DO appeared to be the main reason for the increase of worm’s deep migration. The results confirmed that worm drift from sediment to overlying water, which was influenced by the temperature and DO content, was the main cause of worm pollution in the drinking water plant.

Neuroschistosomiasis due to Schistosoma mansoni: a review of pathogenesis, clinical syndromes and diagnostic approaches

Neuroschistosomiasis (NS) is the second most common form of presentation of infection by the trematode, Schistosoma mansoni. Granulomatous inflammatory reaction occurs as a result of schistosome eggs being transmitted to spinal cord or brain via the vascular system, or by inadvertent adult worm migration to these organs. The two main clinical syndromes are spinal cord neuroschistosomiasis (acute or subacute myelopathy) and localized cerebral or cerebellar neuroschistosomiasis (focal CNS impairment, seizures, increased intracranial pressure). Presumptive diagnosis of NS requires confirming the presence of S. mansoni infection by stool microscopy or rectal biopsy for trematode eggs, and serologic testing of blood and spinal fluid. The localized lesions are identified by signs and symptoms, and confirmed by imaging techniques (contrast myelography, CT and MRI). Algorithms are presented to allow a stepwise approach to diagnosis.

Infrapopulation dynamics of Gyrdicotylus gallieni (Monogenea: Gyrodactylidae)

SUMMARYGyrdicotylus gallieni is a viviparous gyrodactylid monogenean that infects the buccal cavity and pharynx oi Xenopus laevis laevis. Offspring directly recolonize the same host as their parent and transmission is carried out exclusively by adult worms which are capable of leech-like stepping locomotion. The infrapopulation dynamics (at 20 °C) of this species were studied by experimental exposure to single worms of previously uninfected hosts (which were dissected at various time intervals post-infection). Infrapopulations increased exponentially until 50 days post-infection (p.i.), during which time the intrinsic rate of increase was estimated by regression as 0·065/parasite/day. After this, infrapopulation sizes showed greater variability, with established infections becoming extinct 2–5 months p.i.: elimination was probably due to someform of host reaction, as parasite lineages were maintained for up to 10 months by transfers to successive uninfected hosts.The development of infrapopulations is similar to that reported for other viviparous gyrodactylids parasitic on the bodysurface of teleosts. However, the intrinsic rate of increase was comparatively slow in G. gallieni and the duration of infection in isolated hosts prolonged. Slow-growing infrapopulations may elicit a host response more slowly and extend the period during which dispersal to a new host or host population can occur. This might be important in G. gallieni for which the internal site of infection could limit the transmission rate, as worm migration from the oral cavity or accidental detachment and expulsion is necessary for host-host transfer to occur. Exposure of wild caught X. l. laevis of unknown infectionhistory to 1 (n = 33) or 10 (n = 10) worms produced only 2 established infrapopulations (in both cases hosts initially infected by single worms), compared with establishment of over 60% in naive hosts infected with single worms: this suggests that host resistance may be an important factor in the population dynamics of G. gallieni.

Schistosoma mansoni: evidence that ‘non-permissiveness’ in 129/Ola mice involves worm relocation and attrition in the lungs

Summary129/Ola mice resemble WEHI 129J mice in that around 70% of the individuals in any given population resist a primary infection withSchistosoma mansoni. Squashed-organ autoradiographic tracking of [Se]selenomethionine-labelled parasites has shown that the kinetics of worm migration in 129/Ola mice follows the expected pattern, and that all rodents harbour essentially similar numbers of worms on day 14 post-infection. Combined lung and liver worm recovery techniques have revealed, however, that segregation of mice into ‘permissive’ and ‘non-permissive’ individuals can first be detected on day 20. ‘Non-permissive’ mice are characterized by the absence of schistosome eggs at all times in the liver parenchyma and, in consequence, lack the attendant manifestations of pathology; they do, however, harbour a few stunted worms in the liver and significant numbers of adult schistosomes in the pulmonary vasculature. Histological analysis of sectioned lung tissue from such animals indicates that some lung-located schistosomes feed, pair and lay eggs. Nevertheless, eosinophil-enriched inflammatory reactions develop around such worms and the parasites themselves exhibit various manifestations of trauma, ranging from minor vacuolation to gut herniation and extrusion. The phenomenon of ‘non-permissiveness’ thus involves retardation of worm development in the liver and, in consequence, relocation of the parasites to the lungs, where they become subject to host effector responses.