World J Gastroenterol. 2010 February 14; 16(6): 698-702.
Published online 2010 February 14. doi: 10.3748/wjg.v16.i6.698.
Capillaria hepatica in China
Chao-Ding Li, Hui-Lin Yang and Ying Wang.
Chao-Ding Li, Hui-Lin Yang, Department of Orthopedics, First Affiliated Hospital of Soochow University, Soochow 215006, Jiangsu Province, China
Ying Wang, Department of Hematology, First Affiliated Hospital of Soochow University, Soochow 215006, Jiangsu Province, China
Author contributions: Li CD, Yang HL and Wang Y all contributed to this paper.
Correspondence to: Hui-Lin Yang, Professor, Department of Orthopedics, First Affiliated Hospital of Soochow University, Soochow 215006, Jiangsu Province, China. hlyangsd@126.com
Telephone: +86-512-67780429 Fax: +86-512-67780999
Received October 11, 2009; Revised December 9, 2009; Accepted December 16, 2009;
Abstract
Capillaria hepatica (C. hepatica) is a parasitic nematode causing hepatic capillariasis in numerous mammals. Ecologic studies showed that the first hosts of C. hepatica were rodents, among which rats had relatively high infection rates, which explains why C. hepatica spreads globally. Anatomical studies showed that the liver was the principal site of colonization by these parasites and physical damage tended to occur. Although C. hepatica might lead to serious liver disorders, relevant clinical reports were rare, because of the non-specific nature of clinical symptoms, leading to misdiagnosis. This review mainly focuses on the biological characteristics and epidemiology of C. hepatica in China and histopathologic changes in the liver, with expectation of gaining a better understanding of the disease and seeking more effective treatment.
Keywords: Capillaria hepatica, Enoplida infections, Liver diseases, Host-parasite interactions, Diagnosis, Treatment
INTRODUCTION
Capillaria hepatica (C. hepatica) is a nematode parasite of wild rodents and other mammals and has worldwide distribution[1-8]. Adult worms colonize the liver of the host[6,9-11]. They can cause hepatica capillariasis, a serious liver disorder, which may be found both in humans and animals[11-14]. These parasites could be accidentally transmitted to humans by ingestion of embryonated eggs. Up to the year 2000, 37 cases of human infections had been documented[15]. However, there are few reports of the pathology of the infection, which results in serious effects in subjects because of the special anatomic area in which C. hepatica congregates. Clinical symptoms of hepatica capillariasis were non-specific with manifestations of persistent fever, hepatomegaly, eosinophilia and, more seriously, death.
MORPHOLOGY AND BIOLOGICAL FEATURES
Morphology
A typical adult C. hepatica takes the shape of a slender nematode, with the anterior part of the body narrow, and the posterior part gradually swelling. The females measure about 53-78 mm × 0.11-0.20 mm, but males are approximately 24-37 mm × 0.07-0.10 mm. The esophagus is long, occupying half of the body of the female and a third of the male body. The cauda of C. hepatica bears a copulatory spicule and sheath. The eggs of C. hepatica resemble those of Trichuris trichiura, but differ in size. The C. hepatica egg is about 48-66 ?m × 28-36 ?m, and numerous minipores can be seen in the outer shell[16].
Biological features
C. hepatica parasites live in liver parenchyma, where they become biologically mature, then lay eggs in this site. Eggs are immature when produced in the first 4 wk, and these eggs will develop into larvae under favorable conditions of appropriate temperature and moisture. When embryonated, eggs can be ingested by a predator, their larvae then hatch and invade the intestinal mucosa, transporting themselves via the mesenteric vein and portal vein to the liver. The first ecdysis takes place 3-4 d after their arrival in the liver, followed by the second, third (5-7 d) and fourth (9-16 d) larval stages. In the fourth stage, sexual differentiation starts. After sexual differentiation (male, 18 d; female, 20 d), they will experience their final ecdysis and become fifth-stage larvae. The life-span of the female lasts about 59 d, with 40 d for males[17]. It is worthy of note that eggs produced by females in the liver are metabolically active for a prolonged period of time, but remain immature. The host which has ingested these immature eggs displays a “spurious infection”. In contrast, “true infection” occurs when the host ingests embryonated eggs, which will result in the production of larvae that can invade the intestine wall and lead to hepatica capillariasis.
EPIDEMIOLOGY IN CHINA
Epidemiology in the human population
Reports of the 37 cases of hepatica capillariasis indicate they were scattered predominantly in Japan, India, America, Canada, Brazil, Germany, Italy, Korea and Czechoslovakia[15,18-26]. While only 3 cases of “true infection” had been confirmed in China[27-29], those few cases found in China do not necessarily encompass the overall actual morbidity, as the final diagnosis would have to rely on biopsy or necropsy[30,31], so both the rate of misdiagnosis and missed diagnosis could be higher. Table 1 shows the 3 cases with detailed clinical symptoms.
Table 1
Table 1
Three cases of hepatica capillariasis in China
Epidemiology in the animal population
The chief hosts of C. hepatica are various rodents, including more than 70 species, and the principal hosts include Tamias striatus, squirrel, mole, shrew, opossum, weasel and skunk[32]. In mainland China, the total infection rate of hepatica capillariasis in rodent species ranges widely. Table 2 highlights the infection rate in distinct areas with different rodent species[33-41].
Table 2
Table 2
Infection rate in distinct areas with different rodent species
PATHOLOGY OF HEPATICA CAPILLARIASIS
C. hepatica primarily invade the sinus hepaticus, where they experience maturation and egg-laying. Both the worms and their eggs cause focal chronic inflammation in the liver, and around these worms and eggs appear diverse inflammatory cells, including macrophages, eosinophils, and some multinucleate giant cells. Inflammatory infiltration may persist until the final formation of encapsulation or calcification of dead worms. After the focal parasitic necroinflammatory lesions, septal fibrosis occurs. Although the pathological course of the formation of fibrosis has not been well established, it was speculated that the slow and continuous release of disintegrated products from encapsulated parasitic lesions activated the Kupffer cells, which then promoted the development of fibrosis in the liver[42]. Whether there is a relationship between the focal parasitic hepatic lesions and septal fibrosis remain to be resolved. In the experiment of Gomes et al[12], rats were first infected with 600 embryonated eggs, and then injected with a corticoid and C. hepatica antigen. After treatment, focal inflammation ceased, but there was no evident alteration in the formation of septal fibrosis. These findings indicated that, although focal lesions and septal fibrosis were both caused by C. hepatica infection, they played different roles in the pathological course of the infection. Further studies should be conducted to explore the pathological course of hepatic fibrosis.
DIAGNOSIS
Hepatica capillariasis is an exceptionally rare infection in humans with non-specific clinical manifestations, and frequent misdiagnoses have been made[43]. More importantly, the main difficulties interfering with correct diagnosis were related to the unique biological characteristics of the parasite. Apart from those cases of “spurious infection”, both worms and eggs could not be detected in the peripheral blood and stools of infected hosts, so routine laboratory tests of blood and stools invariably showed negative results. Although liver biopsy was a precise and quick method in confirming C. hepatica infection, it was not the most appropriate one, as biopsy was a traumatic diagnostic approach. With introduction of immuno-techniques, the detection of C. hepatica became more convenient and efficient. Assis and colleagues[12] employed an indirect immunofluorescence test to diagnose hepatica capillariasis successfully. Huang et al[44] developed a diagnostic test for experimental rat hepatica capillariasis using an enzyme-linked immunosorbent assay, with high sensitivity and specificity, which was specific for C. hepatica infection. The tests described above have been considered practical, reliable and sensitive. A sensitive immunological test is useful for particular clinical situations, but it is essential to take account of the epidemiological surveys in local areas, which may help lead to a more comprehensive diagnosis.
The differential diagnosis should include accidental tissue infection by nematodes, including Toxocara cati, Toxocara canis, Fasciola hepatica, and Schistosoma japonicum, hepatitis B virus, hepatitis C virus and visceral larva migrants[45-48].
TREATMENT
Pereira et al[30] reported a case of hepatica capillariasis in Brazil where the male subject with massive C. hepatica infection survived after treatment with prednisone, disophenol, and pyrantel tartrate. Thanks to marked eosinophilia in the peripheral blood and hepatic lesions, the patient underwent initial therapy with prednisone (60 mg/d) for a session of 10 d and sequential maintenance by 10 mg every other 10 d. To kill the parasites, or at least to prevent the production of eggs, the patient was treated with disophenol (2-6-diiodo-4-nitrophenol) intramuscularly in a single dose of 7.5 mg/kg body weight and with pyrantel tartrate orally in a single dose of 30 mg/kg body weight. Three years after the treatment, a needle biopsy of the liver, showed sparse portal fibrosis but it was otherwise normal, and the patient remained well during an 8-year follow-up. Also, medication with albendazole was generally effective[31].
Other than chemical treatment, partial hepatectomy or some distinct surgical intervention proved therapeutically effective in animal experiments in rats. The results revealed morphologically that the fibrosis was unaffected, but its relative quantity within the microscopic field appeared significantly decreased, as a consequence of the increased liver tissue mass following regeneration[49].
RESEARCH ACHIEVEMENTS
While prevalence of C. hepatica is dominant in rodents, other mammalian species showed slight resistance to this infection even in laboratory conditions. Yang et al[50] examined the predisposition to C. hepatica between rats and cats by injecting each animal with embryonated eggs at high density. The long-term investigation revealed that every rat became infected with C. hepatica, while, as was expected, the liver biopsy from cats showed negative results. To further confirm whether there were some differences between rats and mice in the course of the formation of hepatic fibrosis, Andrade et al[13] infected both rats and mice with embryonated eggs, and he found that, although rats and mice both had the same pathological changes in the first stage, there were distinct features in the development of hepatic fibrosis. Researching into the immunological mechanisms of hepatica capillariasis, Kim et al[51] measured cytokine mRNA expression in mice spleen cells and mesenteric lymph node cells. In the earlier stages, expression of T-helper, Th1 and Th2, cells were at a high level, as well as the expression of immunoglobulin G1 and G2. Expression in functional cells in the spleen was relatively higher than in mesenteric lymph node cells, which indicated that the spleen was the main location of the response to the infection rather than the mesenteric lymph node. With the density of egg production, expression of interferon-? became stronger, suggesting that it had significant importance in the defense against infection.
CONCLUSION
C. hepatica can cause a serious liver disorder in its hosts including humans and animals. More simple and accurate diagnostic methods and more effective treatment measures need to be further developed. A better understanding of C. hepatica and hepatica capillariasis would help humans to better combat the disease.
Footnotes
Peer reviewer: Dr. Assy Nimer, Assistant Professor, Liver Unit, Ziv Medical Centre, Box 1008, Safed 13100, Israel
S- Editor Tian L L- Editor Cant MR E- Editor Lin YP
References
1.
Stidworthy MF, Lewis JC, Masters NJ, Boardman SI, Hopper JS, de Linan FJ, Redrobe SP, Sayers G. Capillaria hepatica in primates in zoological collections in the British Isles. Vet Rec. 2009;164:66.
2.
Resendes AR, Amaral AF, Rodrigues A, Almeria S. Prevalence of Calodium hepaticum (Syn. Capillaria hepatica) in house mice (Mus musculus) in the Azores archipelago. Vet Parasitol. 2009;160:340-343.
3.
Quadros RM, Pilati C, Marques SM, Mazzolli M, Benedet RC. Capillaria hepatica in Puma concolor: first report in Brazil. J Zoo Wildl Med. 2009;40:586-587.
4.
Carvalho-Costa FA, Silva AG, de Souza AH, Moreira CJ, de Souza DL, Valverde JG, Jaeger LH, Martins PP, de Meneses VF, Araújo A. Pseudoparasitism by Calodium hepaticum (syn. Capillaria hepatica; Hepaticola hepatica) in the Negro River, Brazilian Amazon. Trans R Soc Trop Med Hyg. 2009;103:1071-1073.
5.
Pizzi R, Gordon JC, Flach EJ, Routh AD, Clark B, Boardman WS. Capillaria hepatica (syn Calodium hepaticum) in primates in a zoological collection in the UK. Vet Rec. 2008;163:690-691.
6.
Tesana S, Puapairoj A, Saeseow O. Granulomatous, hepatolithiasis and hepatomegaly caused by Capillaria hepatica infection: first case report of Thailand. Southeast Asian J Trop Med Public Health. 2007;38:636-640.
7.
Reperant LA, Deplazes P. Cluster of Capillaria hepatica infections in non-commensal rodents from the canton of Geneva, Switzerland. Parasitol Res. 2005;96:340-342.
8.
Redrobe SP, Patterson-Kane JC. Calodium hepaticum (syn. Capillaria hepatica) in captive rodents in a zoological garden. J Comp Pathol. 2005;133:73-76.
9.
Mowat V, Turton J, Stewart J, Lui KC, Pilling AM. Histopathological features of Capillaria hepatica infection in laboratory rabbits. Toxicol Pathol. 2009;37:661-666.
10.
Jeong WI, Do SH, Hong IH, Ji AR, Park JK, Ki MR, Park SC, Jeong KS. Macrophages, myofibroblasts and mast cells in a rat liver infected with Capillaria hepatica. J Vet Sci. 2008;9:211-213.
11.
Oliveira L, de Souza MM, Andrade ZA. Capillaria hepatica-induced hepatic fibrosis in rats: paradoxical effect of repeated infections. Rev Soc Bras Med Trop. 2004;37:123-127.
12.
Gomes AT, Cunha LM, Bastos CG, Medrado BF, Assis BC, Andrade ZA. Capillaria hepatica in rats: focal parasitic hepatic lesions and septal fibrosis run independent courses. Mem Inst Oswaldo Cruz. 2006;101:895-898.
13.
Andrade SB, Andrade ZA. Experimental hepatic fibrosis due to Capillaria hepatica infection (differential features presented by rats and mice). Mem Inst Oswaldo Cruz. 2004;99:399-406.
14.
Ferreira LA, Andrade ZA. Capillaria hepatica: a cause of septal fibrosis of the liver. Mem Inst Oswaldo Cruz. 1993;88:441-447.
15.
Juncker-Voss M, Prosl H, Lussy H, Enzenberg U, Auer H, Nowotny N. Serological detection of Capillaria hepatica by indirect immunofluorescence assay. J Clin Microbiol. 2000;38:431-433.
16.
Hamir AN, Rupprecht CE. Hepatic capillariasis (Capillaria hepatica) in porcupines (Erethizon dorsatum) in Pennsylvania. J Vet Diagn Invest. 2000;12:463-465.
17.
Wright KA. Observation on the life cycle of Capillaria hepatica (Bancroft, 1893) with a description of the adult. Can J Zool. 1961;39:167-182.
18.
Govil H, Desai M. Capillaria hepatica parasitism. Indian J Pediatr. 1996;63:698-700.
19.
Choe G, Lee HS, Seo JK, Chai JY, Lee SH, Eom KS, Chi JG. Hepatic capillariasis: first case report in the Republic of Korea. Am J Trop Med Hyg. 1993;48:610-625.
20.
Cislaghi F, Radice C. Infection by Capillaria hepatica. First case report in Italy. Helv Paediatr Acta. 1970;25:647-654.
21.
Slais J, St?rba J. Solitary liver granulomas in man caused by Capillaria hepatica (Bancroft, 1893) in Czechoslovakia. Folia Parasitol (Praha). 1972;19:373-374.
22.
Pereira VG, França LC. [Human Capillaria hepatica infection. Report of a case treated successfully]. Rev Hosp Clin Fac Med Sao Paulo. 1981;36:31-34.
23.
Slais J. The finding and identification of solitary Capillaria hepatica (Bancroft, 1893) in man from Europe. Folia Parasitol (Praha). 1973;20:149-161.
24.
Vargas Carreto G, López Martínez H, Victoria Victoria R, Hernández Muñoz G. [Capillaria hepatica. Report of the 2nd cased found in the Mexican Republic]. Bol Med Hosp Infant Mex. 1979;36:909-917.
25.
Silverman NH, Katz JS, Levin SE. Capillaria hepatica infestation in a child. S Afr Med J. 1973;47:219-221.
26.
Fan PC, Chung WC, Chen ER. Capillaria hepatica: a spurious case with a brief review. Kaohsiung J Med Sci. 2000;16:360-367.
27.
Xu BK, Li DN. General condition on the rare human parasites in China. Zhonghua Yixue Zazhi. 1979;59:286-290.
28.
Lin XM, Li H, Zhao XD, Lin XD, Li H, Zhao XD, Deng Y. 1 case of capillaria hepatica infection. Zhongguo Jishengchongbing Fangzhi Zahi. 2004;17:230.
29.
Huang JN, Lin JX. The pathological diagnosis of the first case of capillaria hepatica in Fujian province. Zhongguo Renshou Gonghuanbing Zazhi. 2004;20:556.
30.
Pereira VG, Mattosinho Franca LC. Successful treatment of Capillaria hepatica infection in an acutely ill adult. Am J Trop Med Hyg. 1983;32:1272-1274.
31.
Nabi F, Palaha HK, Sekhsaria D, Chiatale A. Capillaria hepatica infestation. Indian Pediatr. 2007;44:781-782.
32.
Solomon GB, Handley CO. Capillaria hepatica (Bancroft, 1893) in Appalachian mammals. J Parasitol. 1971;57:1142-1144.
33.
Zhou ZL, Wu HY, Mao XP, Fang ZM. Investigate the infection rate of capillaria hepatica on rats. Zhongguo Bingyuan Shengwuxue Zazhi. 1991;4:225.
34.
Zhou XM, Zhang GF, Li C, Li FH, Yin ZH, Yang JL, Su P. Investigation on rats infected with Capillaria hepatica in Kunming. Zhongguo Renshou Gonghuanbing Zazhi. 1998;14:33.
35.
Zhang LY, Huang JY, Yang FZ. Investigate on rats infected with capillaria hepatica in Jiangle. Zhongguo Jishengchoubing Fangzhi Zazhi. 2003;16: 19-20.
36.
Yuan GL, Li XY, Chen WJ. Investigation on Rattus losea infected with Capillaria hepatica in Ningde. Zhongguo Meijie Shengwuxue Ji Kongzhi Zazhi. 2000;11:301-302.
37.
Xue YS, Wu CH, Huang MS, Li RH. Investigation on rats infected with capillaria hepatica in Fuqing. Haixia Yufang Yixue Zazhi. 1998;4:31-32.
38.
Tung KC, Hsiao FC, Yang CH, Chou CC, Lee WM, Wang KS, Lai CH. Surveillance of endoparasitic infections and the first report of Physaloptera sp. and Sarcocystis spp. in farm rodents and shrews in central Taiwan. J Vet Med Sci. 2009;71:43-47.
39.
Shen LJ, Luo ZY, Li W, Li ZH, Gao C, Yang WB, Li LY, Qian TJ. Investigation on rats infected with capillaria hepatica in Dali. Zhongguo Jishengchoubing Fangzhi Zazhi. 2003;16:296-298.
40.
Liu YX, Yang ZQ, Meng XR, Wu QY. Investigation on rats infected with capillaria hepatica in some region of Shandong province. Dongwuxue Zazhi. 1997;32:1-3.
41.
Lin XM, Xu BL, Zhao XD, Li H, Huang Q, Deng Y, Hao ZY, Zhang AM. Epidemiological investigation on capillaria hepatica infection among little animal in henan province. Zhongguo Jishengchoubing Fangzhi Zazhi. 2007;2:44-46.
42.
Lemos QT, Magalhães-Santos IF, Andrade ZA. Immunological basis of septal fibrosis of the liver in Capillaria hepatica-infected rats. Braz J Med Biol Res. 2003;36:1201-1207.
43.
Galvão VA. [Capillaria hepatica: an evaluation of its pathogenic role in man]. Mem Inst Oswaldo Cruz. 1981;76:415-433.
44.
Huang HC, Ling HB, Liang SH, Xing WL, Pan CW. Diagnosis of Experimental rat hepatica capillariasis by ELISA. Wenzhou Yixueyuan Xuebao. 2001;31:299-300, 302.
45.
Chen H, He YW, Liu WQ, Zhang JH. Rosiglitazone prevents murine hepatic fibrosis induced by Schistosoma japonicum. World J Gastroenterol. 2008;14:2905-2911.
46.
Dobrucali A, Yigitbasi R, Erzin Y, Sunamak O, Polat E, Yakar H. Fasciola hepatica infestation as a very rare cause of extrahepatic cholestasis. World J Gastroenterol. 2004;10:3076-3077.
47.
Yan KK, Guirgis M, Dinh T, George J, Dev A, Lee A, Zekry A. Treatment responses in Asians and Caucasians with chronic hepatitis C infection. World J Gastroenterol. 2008;14:3416-3420.
48.
Zheng M, Cai WM, Weng HL, Liu RH. ROC curves in evaluation of serum fibrosis indices for hepatic fibrosis. World J Gastroenterol. 2002;8:1073-1076.
49.
Santos CC, Onofre-Nunes Z, Andrade ZA. Role of partial hepatectomy on Capillaria hepatica-induced hepatic fibrosis in rats. Rev Soc Bras Med Trop. 2007;40:495-498.
50.
Yang FZ, Huang XH, Tu ZP, Zhang YZ. Establishment of an animal model of capillaria hepatica infection among little animal in Henan province. Zhongguo Jishengchouxue Yu Jishengchoubing Zazhi. 2000;18:229-231.
51.
Kim DK, Joo KH, Chung MS. Changes of cytokine mRNA expression and IgG responses in rats infected with Capillaria hepatica. Korean J Parasitol. 2007;45:95-102.