Pulmonary sparganosis mansoni: a case report

Pulmonary sparganosis mansoni is uncommon in general clinical practice, but prevalent in endemic foci. Pulmonary sparganosis mansoni shares some clinical and radiologic similarities that mimic other common pulmonary pathogens. Delayed diagnosis of pulmonary sparganosis mansoni can pose a significant hazard to the patient. Indeed, a history of ingesting uncooked stone cracks in endemic areas is strongly suggestive of the possibility of pulmonary sparganosis mansoni. We report a case of a 43-year-old male peasant infested with pulmonary sparganosis mansoni who had been misdiagnosed with pulmonary tuberculosis.

[Effect of physicochemical factors on infectivity of Spirometra mansoni plerocercoid]

OBJECTIVE

To observe the effect of different physicochemical factors on the infectivity of Spirometra mansoni plerocercoids.

METHODS

The muscle samples with plerocercoids taken from Rana nigromaculata (about 1 cm3 each piece) were treated with different temperature (-20 degrees C, 4 degrees C, 37 degrees C and 56 degrees C) or different concentrations of ethanol (20%, 30%, 40%, 50% and 60%) for 1, 2 or 3 h, or soaked in ginger juice, vinegar (total acid concentration of 4.5%, pH 3.05) or soy sauce (containing 19.3% NaCl) for 3, 6, 12 or 24 h. The muscle with plerocercoids treated with normal saline under 20 degrees C served as control. 30 plerocercoids were used under each condition and fed to 10 mice averagely (3 larvae/mouse). Another 20 plerocercoids with frog meat were comminuted for 3 min then fed to 10 mice. One week later, the mice were sacrificed to collect the parasitic plerocercoids and the number of positive mice and plerocercoids was recorded.

RESULTS

None of the mice fed with plerocercoids treated under -20 degrees C for 2 h was infected. All the mice fed with plerocercoids treated under 56 degrees C for 2 h and 3 h were infected. The percentage of infective plerocercoids was 60% (18/30) and 43% (13/30), respectively, considerably lower than those of the control (90%, 27/30) (P < 0.05). None of the mice fed with plerocercoids soaked in 60% ethanol for 2 h was infected. All the mice fed with plerocercoids soaked in 60% ethanol for 1 h, or in 50% ethanol for 2 h or 3 h were infected. The percentage of infective plerocercoids was 60% (18/30), 57% (17/30), and 50% (15/30), respectively, considerably lower than those of the control (93%, 28/30) (P<0.05). None of the mice fed with plerocercoids soaked in vinegar for 24 h, or soy sauce for 6 h was infected. The infectivity of the plerocercoids treated by ginger juice for 24 h was similar to the control (P>0.05). Among the ten mice fed with comminuted frog meat with plerocercoids, five were infected with 6 plerocercoids.

CONCLUSION

Treatment with -20 degrees C or 60% ethanol for 2 h, soy sauce for 6 h, or vinegar for 24 h can destroy the infectivity of plerocercoids in 1 cm3 frog muscle.

Human sparganosis in Thailand: an overview

Human sparganosis is caused by cestode larvae (spargana) of the genus Spirometra, which exploit copepods as the first intermediate host. A wide range of amphibians, reptiles, birds, and mammals serve as second intermediate/paratenic hosts. Human infections occur mainly by ingesting raw intermediate/paratenic hosts. Cases are found mainly in China, Japan and Korea, and sporadically also in Thailand and other Asian countries. In the period 1943-2010, there were 52 reported cases of sparganosis in Thailand. The average patient age was 32 years (range 11-82 years). From the available patient information, the prevalence of sparganosis infection was higher among females than males, at a ratio of F:M=2:1 (27:15). Patients have mainly been found in the northeast, north, and central regions of Thailand, with only a few in the south. Although a single subcutaneous nodular lesion was the most common feature, about one third of patients had ocular lesions. In particular, patients having ocular lesions were about half of total cases reported pre-1990, with several confirmed cases' applying fresh frog muscle as a poultice to relieve sore eyes, according to traditional medicine. In Thailand, sparganosis is not merely a food-borne disease but is also caused by the traditional belief of applying frog muscles (contaminated with sparganum) to sore eyes.

[Human plerocercoidosis and sparganosis: I. A historical review on aetiology]

Plerocercoid should not be confused with Sparganum. The scolex of plerocercoid has a bothrium or bothrial slit but there is no true scolex in sparganum. Plerocercoid is a developmental stage of an animal tapeworm, genus Spirometra. Sparganum is another generic name of a pseudophyllidean cestode. Plerocercoid causes benign plerocercoidosis and sparganum causes "malignant sparganosis". Plerocercoidosis is a parasitic zoonosis which can be food-borne, water-borne, contact-borne or mother-borne. During the past 20 years, there has been significant progress in studies of human plerocercoidosis and sparganosis, especially the former. Spirometra erinacei-europiea plerocercoidosis and sparganosis prolifera distributed mainly in East Asia. Spirometra mansonoides plerocercoidosis has been reported from the USA. Up to the present, approximately 1400 cases of plerocercoidosis were reported from China, Japan, Korea, USA and Thailand, and at least 16 well-documented cases of human proliferating sparganosis were reported worldwide (in Japan, China, Thailand, USA, Paraguay, Venezuela, and the Philippines). The life cycle of Sparganum is unknown. For plerocercoid, human being acts as a dead-end hosts, copepod and frogs serve as intermediate hosts, and snakes and carnivorous animals are its paratenic hosts. This review summarizes the research progress on aetiology and pathogenesis of human plerocercoidosis and sparganosis. The second part (in press) will be concentrated on their pathology, clinical manifestations, diagnosis, treatment, epidemiology, control and prevention.

[Infectivity of the sparganum treated by praziquantel, gamma-irradiation and mechanical cutting]

An experimental study was performed to observe the infectivity of sparganum (plerocercoid of Spirometra erinacei) treated by praziquantel, gamma-irradiation and mechanical cutting. The spargana were obtained from the naturally infected European grass snake, Rhabdophis tigrina, or from the experimentally infected mice. A total of 83 mice (ICR strain) were divided into 3 experimental groups by the source of the damage, fed each with 5 spargana, and sacrificed 1 month later for worm recovery. In the praziquantel group, the worms were incubated in the concentration of 10 micrograms/ml (control: Tyrode for 4 hours) for 0.5, 1, 2 and 4 hours at 36 degrees C, and fed to mice. The recovery rate from mice in praziquantel group was not different from that (80%) of control group and in the range of 76-100%. In the gamma-irradiation group, the worms were irradiated by 10-1000 Gy with Cs137. The average recovery rates of 69-100% were not different from that of control up to 100 Gy. The rate was 56% under 150 Gy, and 5% by 1000 Gy. In the mechanical cutting group, the worms were cut at 0.5, 1, 2 and 3 mm from the anterior end of the scolex. The average recovery rates in each group were 70-90% and that of control was 90%. The present finding suggests that the sparganum be highly resistant to praziquantel, gamma-irradiation and mechanical cutting. The vitality center of the sparganum must be at the anterior end of its scolex.

Studies on Spirometra theileri (Baer, 1925) n. comb. 3. Acquired immunity to reinfection with plerocercoids in mice

100 male T.O. strain laboratory mice were divided into 4 equal groups: (I) 25 were injected intramuscularly with an antigen prepared together with Freund's adjuvant; (II) 25 injected with antigen alone; (III) 25 infected subcutaneously with 8 live plerocercoids of the same species; (IV) 25 served as controls. 4 weeks later all mice were given 6 live plerocercoids orally. The presence of acquired immunity in group III was shown by a significant reduction in the numbers, size and motility of challenge worms. The host response was greater in all the immunized groups than in the controls.

Studies on Spirometra theileri (Baer, 1925) n. comb. 2. Pathology of experimental plerocercoid infections

The pathology associated with the early migratory phase of infection by the sparganum larvae of Spirometra theileri (Baer, 1925) Opuni and Muller, 1974 (Pseudophyllidea:Diphyllobothriidae), has been investigated in TO strain mice and in rhesus monkeys (Macaca mulatta). All infected mice developed haemorrhagic skin lesions and oedema of the joints and often ascites and peritonitis 3-6 weeks after infection. There was a 25% mortality in mice given plerocercoids orally, 37.5% in those injected with procercoids intraperitoneally. From eight weeks after infection larvae in both mice and monkeys were at various stages of encapsulation. One monkey which died three weeks after oral infection with 100 procercoids had developed ascites, haemorrhagic lesions and an acute peritonitis; infarcts were observed in the liver, lungs and spleen. In plerocercoid infections, scolices migrated directly through the duodenal wall within 45 minutes of oral infection in mice and 2 hours in monkeys, causing a minimum of damage apart from small haemorrhagic patches at the sites of penetration. In monkeys an eosinopoenia occurred 7 days after infection (a mean drop from 300 to 150 cells per cu mm), followed by a sudden rise (maximum of 1450 cells per cu mm) lasting from the 3rd to the 7th week. The histopathology and immunopathology associated with the various phases of infection were investigated in both mice and monkeys.