Visceral larva migrans and pyogenic liver abscess

Parasite-bacteria interrelationship

Parasites and bacteria have co-evolved with humankind, and they interact all the time in a myriad of ways. For example, some bacterial infections result from parasite-dwelling bacteria as in the case of Salmonella infection during schistosomiasis. Other bacteria synergize with parasites in the evolution of human disease as in the case of the interplay between Wolbachia endosymbiont bacteria and filarial nematodes as well as the interaction between Gram-negative bacteria and Schistosoma haematobium in the pathogenesis of urinary bladder cancer. Moreover, secondary bacterial infections may complicate several parasitic diseases such as visceral leishmaniasis and malaria, due to immunosuppression of the host during parasitic infections. Also, bacteria may colonize the parasitic lesions; for example, hydatid cysts and skin lesions of ectoparasites. Remarkably, some parasitic helminths and arthropods exhibit antibacterial activity usually by the release of specific antimicrobial products. Lastly, some parasite-bacteria interactions are induced as when using probiotic bacteria to modulate the outcome of a variety of parasitic infections. In sum, parasite-bacteria interactions involve intricate processes that never cease to intrigue the researchers. However, understanding and exploiting these interactions could have prophylactic and curative potential for infections by both types of pathogens.

[A case of hepatic abscess caused by toxocara]

Toxocariasis is a helminozoonosis caused by the infection of a human host by the larva of Toxocara canis and Toxocara catis, which are common nematodes in dogs and cats, and occurs more frequently in school age children. Toxocariasis shows variable clinical manifestations including hepatomegaly, bronchial asthma, uveitis, central nervous system symptoms with peripheral eosinophilia and an increased total serum IgE level. However a hepatic abscess caused by toxocara infection in adults is rare. We experienced a case of heavy alcoholic patients with a hepatic eosinophilic abscess caused by toxocara infestation, which was confirmed by microscopic examination of liver biopsy, enzyme-linked immunosorbent assay test, abdominal CT and the ultrasonography findings.

Severe hepatic involvement in visceral larva migrans

Because of its anatomical position, the liver may be involved in many protozoan and helminthic gastrointestinal infections. Visceral larva migrans caused by Toxocara canis is rarely taken into account in adult patients with cholestatic syndrome, especially when liver disease is not associated with hypereosinophilic reaction. We report on a 74-year-old immunocompetent woman who presented with fever, bronchospasm, erythema nodosum, weight loss and progressive jaundice. A liver biopsy showed caseating granulomatous hepatitis with secondary portal fibrosis and paucity of interlobular bile ducts. A step-by-step search for aetiological factors led us to a diagnosis of toxocariasis (positive enzyme-linked immunosorbent assay IgG test). An excellent clinical response to combined treatment with steroid and diethylcarbamazine, and a reduction in the antibody level against T. canis supported the diagnosis. Computed tomography and laparoscopy demonstrated multiple small mass lesions and fibrous perihepatitis. This report shows that visceral larva migrans may be a cause of prostrating chronic liver disease and should be suspected in every febrile patient with cryptogenic cholestatic hepatitis.

Pyogenic abscesses and parasitic diseases

Parasitic diseases which during their course in the host switch the immune system from a T helper 1 to a T helper 2 response may be detrimental to the host, contributing to granuloma formation, eosinophilia, hyper-IgE, and increased susceptibility to bacterial and fungal infections. Patients and animals with acute schistosomiasis and hyper-IgE in their serum develop pyogenic liver abscess in the presence of bacteremia caused by Staphylococcus aureus. The Salmonella-S. mansoni association has also been well documented. The association of tropical pyomyositis (pyogenic muscle abscess) and pyogenic liver abscess with Toxocara infection has recently been described in the same context. In tropical countries that may be an interesting explanation for the great morbidity of bacterial diseases. If the association of parasitic infections and pyogenic abscesses and/or fungal diseases are confirmed, there will be a strong case in favor of universal treatment for parasitic diseases to prevent or decrease the morbidity of superinfection with bacteria and fungi.

Human toxocariasis and pyogenic liver abscess: a possible association

OBJECTIVES

To study the role of human toxocariasis in the pathogenesis of pyogenic liver abscess.

METHODS

We compared the serology for toxocariasis and serum levels of IgE in 16 patients with pyogenic liver abscess to those in 32 matched (age and gender) controls to define the possible association between these two entities.

RESULTS

The serology for toxocariasis was positive in 10 of 16 patients compared with 4 of 32 controls. The relative odds and 95% confidence interval (conditional logistic regression), comparing cases and matched controls, was significant (1.4; 95% confidence interval, 1.1-1.7) for Toxocara serology. Regarding IgE serum levels, there was no difference between cases and controls.

CONCLUSIONS

Human toxocariasis can be one of the predisposing causes of pyogenic liver abscess, especially in tropical countries in which this parasitic disease is common. Treatment of human toxocariasis may prevent morbid complications like hepatic abscess and should be considered in patients with clinical and/or serological evidence of Toxocara infection.

Toxocarosis as zoonosis. A review of literature and the prevalence of Toxocara canis antibodies in 511 serum samples

A total of 511 serum samples from children aged between 6 months to 15 years old, with different clinical signs-living in the region of Northern Greece - were tested by ELISA (enzyme links immunosorbent assay) technique, for the detection of specific IgG and IgM antibodies against T. canis antigen. The reason IgM was detected was because IgM levels are elevated in the acute phase of toxocara infection, in spite of their notorious non-specificity. In this seroepidemiologic survey of children, a remarkably high percentage (12.5%) reacted positively to this method. Sixteen (3.1%) out of 511 sera showed IgG antibodies, 43 (8.4%) showed IgM, while 5 (1%) showed both IgG and IgM antibodies against T. canis E/S (excretory - secretory) antigen. Females were significantly more infected than males. Seropositivity rate was highest in children over the age of 10.

[The association between human toxocariasis and pyogenic abscesses]

The association between hepatic abscesses and schistosomiasis mansoni was confirmed by clinical and experimental studies. Other parasites may cause systemic immunologic changes and local structural alterations in the affected organs that can facilitate the seeding of these areas by bacteria. Tropical pyomyositis, pyogenic liver and renal abscesses are frequent diseases in tropical areas. The visceral larva migrans syndrome is caused by the presence, in the human body, of larvae of worms that have other animals as their definitive host, most commonly being caused by Toxocara canis. The larvae migrate to various body organs leading to many inflammatory reactions in the form of granuloma and tissue necrosis. In this review we discuss the possible host-parasite-bacteria interactions that would favour the formation of abscesses in the organs involved by the larva of T. canis and present preliminary results of a clinical and experimental study undertaken during the last four years to define the role of this parasite in the pathogenesis of the abscesses.