Tropical pyomyositis and human toxocariasis: a clinical and experimental study

Purulent infectious myositis (formerly tropical pyomyositis)

Purulent infectious myositis (PIM), formerly known as tropical pyomyositis, is a pyogenic infection of skeletal muscles. Staphylococcus aureus, a normal human skin inhabitant, is the main pathogen involved, but multiple other microorganisms have been implicated. Although usually a progressive febrile disease with pain in the affected muscle(s), severe, life-threatening forms have been described, especially in immunosuppressed patients and children. PIM may elude early diagnosis given the lack of overlying skin changes. Hence, high index of suspicion followed by imaging modalities (ultrasonography when superficial and computed tomography or magnetic resonance imaging with contrast when deep) help confirm the diagnosis. Treatment requires combination of percutaneous or open surgical drainage along with antimicrobial therapy guided by culture results. The rising incidence of cases due to methicillin-resistant Staphylococcus aureus (MRSA) strains, makes the inclusion of vancomycin be recommended. This paper reviews PIM highlighting its global distribution, causative agents, predisposing factors, management, and potential complications.

[Infectious myositis]

Infectious myositis is a rare condition that can be caused by bacteria, viruses, parasites or fungi. Muscle pain or weakness are symptoms shared by all type of myositis. Diagnosis is made on clinical presentation: fever and poor general state is found in bacterial myositis, diffuse muscle pain with flu-like symptoms in viral causes, eosinophilia and a tropical travel history can be related to parasitic etiology, and immunocompromising condition suggests fungal infection. Rhabdomyolysis, leukocytosis and elevated C-reactive protein are common. Imaging (computed tomography or magnetic resonance imaging) can be useful to detect which muscle is affected. The causative organism can be identified on blood cultures, skeletal muscle biopsy, serology or any other pathogen specific test. Treatment depends on the causative organism. Open surgical or imaging-guided drainage is usually necessary in bacterial myositis.

Prevalence of Toxoplasma gondii and Toxocara canis Among Myositis Patients in the Southwest of Iran

INTRODUCTION

Parasitic myositis is caused by some parasites, such as Toxoplasma gondii) T. gondii (and Toxocara canis (T. canis). So, the aim of the study was to evaluate the prevalence T. gondii and T. canis in patients with myositis and healthy individuals.

METHODS

A total of 108 samples were randomly selected as the control (54 healthy individuals) and test (54 myositis patients) groups. IgG and IgM antibodies (Ab) against T. gondii and IgG Ab against T. canis were measured by the enzyme-linked immunosorbent assay (ELISA). The detection of chronic and acute toxoplasmosis was performed by the ELISA IgG avidity. The presence of T. gondii in the blood was evaluated using the nested polymerase chain reaction (nested-PCR).

RESULTS

Of 108, 33 (30.6%) cases were positive for IgG against T. gondii that 19 (35.2%) and 14 (25.9%) were observed in myositis patients and healthy individuals, respectively (P=0.296). Of 19 positive cases, 12 (63.2%) and 7 (36.8%) cases were detected as chronic and acute toxoplasmosis, respectively, while, all positive cases in the control group had chronic toxoplasmosis (P=0.013). One (1.9%) sample was positive for anti- T. gondii IgM and two (3.7%) samples were positive for IgG against T. canis by the ELISA that these positive cases were observed only in myositis patients (P=1.000 P=0.495, respectively). B1 T. gondii gene was amplified in 12 (63.2%) and 1 (7.1%) in myositis patients and healthy subjects (P=0.001).

CONCLUSION

Our findings showed that there was a relatively high prevalence of acute toxoplasmosis in myositis patients in comparison with the control subjects in the Southwest of Iran.

A 12-year-old Child with Trichinellosis, Pyomyositis and Secondary Osteomyelitis

Trichinellosis is a parasitic infestation affecting the skeletal muscles. Cases of trichinellosis in humans have been reported from most regions of the world. However, a review of literature revealed only two reported cases of human trichinellosis in India. Further, a diagnosis of superimposed pyomyositis in trichinellosis with secondary osteomyelitis has not been reported to our knowledge. This article reports this rare case presentation in a 12-year-old child. Timely intervention helped prevent long-term morbidity in our patient. In our case report, we also discuss in detail the pathogenesis of such a condition and discuss the role of imaging modalities and an early magnetic resonance imaging (MRI) to diagnose the condition and start an early treatment.

Pyomyositis in the upper Negro river basin, Brazilian Amazonia

Pyomyositis remains poorly documented in tropical Latin America. We therefore performed a retrospective review of cases admitted to a hospital in the upper Negro river basin during 2002-2006. Seasonality was assessed by the cosinor model and independent predictors of outcome were identified by logistic regression. Determinants of time-to-fever resolution were analysed using Cox regression. No seasonal trend was observed (p=0.284) among 82 hospitalised patients. The disease predominated in young males and the most commonly affected part of the body was the lower limb (68 [63.5%] out of 107 lesions). Staphylococcus aureus was the only identified infecting organism (18 of 20 culture results, 90%). Complications occurred in 17 patients (20.7%) and the case fatality rate was 2.4%. Children were more likely to present with eosinophilia than adults (OR= 4.20, 95% CI 1.08-16.32, p=0.048), but no other significant differences regarding clinical presentation and outcomes were observed. The time-to-fever resolution was the only independent determinant of poor outcome (OR=1.52, 95% CI 1.22-1.92, p<0.001) and was significantly longer in patients treated with combined antibiotic therapy than in those treated with single antibiotics (HR=0.523, 95% CI 0.296-0.926, p=0.026). Further studies to determine the best antibiotic therapy modality for the treatment of pyomyositis are required.

Parasitic infections and myositis

Infectious myositis may be caused by a wide variety of bacterial, fungal, viral, and parasitic agents. Parasitic myositis is most commonly a result of trichinosis, cystericercosis, or toxoplasmosis, but other parasites may be involved. A parasitic cause of myositis is suggested by history of residence or travel to endemic area and presence of eosinophilia. The diagnosis of parasitic myositis is suggested by the clinical picture and radiologic imaging, and the etiologic agent is confirmed by parasitologic, serologic, and molecular methods, together with histopathologic examination of tissue biopsies. Therapy is based on the clinical presentation and the underlying pathogen. Drug resistance should be put into consideration in different geographic areas, and it can be avoided through the proper use of anti-parasitic drugs.

Acute schistosomiasis mansoni: revisited and reconsidered

Acute schistosomiasis is a systemic hypersensitivity reaction against the migrating schistosomula and eggs. A variety of clinical manifestations appear during the migration of schistosomes in humans: cercarial dermatitis, fever, pneumonia, diarrhoea, hepatomegaly, splenomegaly, skin lesions, liver abscesses, brain tumours and myeloradiculopathy. Hypereosinophilia is common and aids diagnosis. The disease has been overlooked, misdiagnosed, underestimated and underreported in endemic areas, but risk groups are well known, including military recruits, some religious congregations, rural tourists and people practicing recreational water sports. Serology may help in diagnosis, but the finding of necrotic-exudative granulomata in a liver biopsy specimen is pathognomonic. Differentials include malaria, tuberculosis, typhoid fever, kala-azar, prolonged Salmonella bacteraemia, lymphoma, toxocariasis, liver abscesses and fever of undetermined origin. For symptomatic hospitalised patients, treatment with steroids and schistosomicides is recommended. Treatment is curative in those timely diagnosed.

Human toxocariasis: contribution by Brazilian researchers

In the present paper the main aspects of the natural history of human infection by Toxocara larvae that occasionally result in the occurrence of visceral and/or ocular larva migrans syndrome were reviewed. The contribution by Brazilian researchers was emphasized, especially the staff of the Tropical Medicine Institute of São Paulo (IMT).

Bacterial, fungal, parasitic, and viral myositis

Infectious myositis may be caused by a broad range of bacterial, fungal, parasitic, and viral agents. Infectious myositis is overall uncommon given the relative resistance of the musculature to infection. For example, inciting events, including trauma, surgery, or the presence of foreign bodies or devitalized tissue, are often present in cases of bacterial myositis. Bacterial causes are categorized by clinical presentation, anatomic location, and causative organisms into the categories of pyomyositis, psoas abscess, Staphylococcus aureus myositis, group A streptococcal necrotizing myositis, group B streptococcal myositis, clostridial gas gangrene, and nonclostridial myositis. Fungal myositis is rare and usually occurs among immunocompromised hosts. Parasitic myositis is most commonly a result of trichinosis or cystericercosis, but other protozoa or helminths may be involved. A parasitic cause of myositis is suggested by the travel history and presence of eosinophilia. Viruses may cause diffuse muscle involvement with clinical manifestations, such as benign acute myositis (most commonly due to influenza virus), pleurodynia (coxsackievirus B), acute rhabdomyolysis, or an immune-mediated polymyositis. The diagnosis of myositis is suggested by the clinical picture and radiologic imaging, and the etiologic agent is confirmed by microbiologic or serologic testing. Therapy is based on the clinical presentation and the underlying pathogen.

Neurotoxocarosis

Infection of humans with embryonated eggs of Toxocara canis (larva migrans) remains asymptomatic, or results in covert or common toxocarosis, visceral larva migrans syndrome, or ophthalmologic and neurologic impairment. Though neurological manifestations of Toxocara canis larvae are rare, toxocarosis remains an important differential diagnosis of various neurological disorders. Manifestations of the central nervous system are dementia, meningo-encephalitis, myelitis, cerebral vasculitis, epilepsy, or optic neuritis. Manifestations of the peripheral nervous system comprise radiculitis, affection of cranial nerves, or musculo-skeletal involvement. If toxocarosis is neglected, ignored, or refused as a differential of these abnormalities, it may be easily overlooked for years. Early recognition and treatment of the infection is, however, of paramount importance since it reduces morbidity and mortality and the risk of secondary superinfection. Like the visceral manifestations, neurological manifestations of toxocarosis are treated by benzimidazole components, most frequently albendazole, corticosteroids, or diethylcarbamazine. If detected and treated early, the prognosis of neurological manifestations of toxocarosis is favourable.

Schistosomiasis mansoni and severe gastrointestinal cytomegalovirus disease in a patient with acquired immunodeficiency syndrome

The behavior of the Schistosoma mansoni infection in patients with AIDS has not been explored. The case of a young woman with schistosomiasis mansoni, AIDS, and cytomegalovirus disease is reported. The authors suggest that the helminth was not a bystander in this case, or rather, by interfering with the host's immune response, it set the stage for the development and/or aggravation of the viral infection.

Manifestation of toxocariasis in children with neuroblastoma treated with autologous hematopoietic transplants

Toxocariasis was diagnosed in 3 out of 22 children (14%) treated in our center with high-dose chemotherapy and autologous hematopoietic stem cell transplantation (HSCT). The patients were coming from rural areas in the southeastern Poland and did not present any clinical symptoms of toxocariasis upon admission to the hospital. Although no neurological and ophthalmological abnormalities were noticed, the atypical form of toxacariasis was diagnosed based on elevated eosinophils counts, positive serological tests, and biochemical symptoms of liver damage. The authors conclude that toxocariasis should be taken into consideration in the differential diagnosis of eosinophilia in children undergoing high-dose chemotherapy and HSCT, especially if they are coming from rural areas.

Tropical and Temperate Pyomyositis

Pyomyositis is a primary infection of skeletal muscle not arising from contiguous infection, presumably hematogenous in origin, and often, but not invariably, associated with abscess formation. Classically, pyomyositis is an infection of the tropics, occurring in previously active and healthy young men. Pyomyositis in temperate countries is often regarded as an infection that occurs in hosts who are immunocompromised or otherwise debilitated. However,this distinction may be somewhat artificial, as tropical pyomyositis may be partly related to underlying infection with HIV or parasites, and temperate pyomyositis has been reported in healthy and athletic persons. This article discusses the pathogenesis, clinical presentation, diagnosis, and management of pyomyositis in the tropical and temperate settings.

Alteration in the endogenous intestinal flora of swiss webster mice by experimental Angiostrongylus costaricensis infection

The association between worm infections and bacterial diseases has only recently been emphasized. This study examined the effect of experimental Angiostrongylus costaricensis infection on endogenous intestinal flora of Swiss Webster mice. Eight mice aging six weeks were selected for this experiment. Four were infected with A. costaricensis and the other four were used as controls. Twenty eight days after the worm infection, all mice in both groups were sacrificed and samples of the contents of the ileum and colon were obtained and cultured for aerobic and anaerobic bacteria. In the mice infected with A. costaricensis there was a significant increase in the number of bacteria of the endogenous intestinal flora, accompanied by a decrease in the number of Peptostreptococcus spp. This alteration in the intestinal flora of mice infected by the nematode may help to understand some bacterial infections described in humans.

[Toxocariasis in adults]

PURPOSE

Toxocariasis is a widespread zoonotic parasitosis that is frequent in France. It is due to the presence of larvae of roundworms belonging to the genus Toxocara in the human body. Clinical signs are often non-specific. The disease can be asymptomatic or can lead to death. Toxocariasis can be thought of because of clinical signs or presence of hypereosinophilia, but the diagnosis is made by specific serology. Since there is no consensus to date regarding treatment, prevention is of paramount importance.

CURRENT KNOWLEDGE AND KEYPOINTS

Recent studies point out the frequency of this parasitic disease that is often asymptomatic. The serological diagnosis remains the main tool for the diagnosis of toxocariasis.

FUTURE PROSPECTS AND PROJECTS

Further studies on toxocariasis should focus on the prevalence of this disease in French population regarding the probability of infection: living in the countryside, food habits, hygiene and presence of dogs in the neighborhood. Tools of the biological diagnosis (mainly serological techniques) should be improved, but, especially, studies should focus on the evaluation of specific treatment in order to give unquestionable guidelines on this point.

Infectivity and pathogenicity of 14-month-cultured embryonated eggs of Toxocara canis in mice

Infectivity and pathogenicity to mice of embryonated eggs of Toxocara canis, that had been maintained in 2% formalin for 14 months at 4 degrees C, were evaluated by immunological and pathological assessment at 1, 4, 8, 12, 16, 20, 24, 28, 42 and 67 weeks post-infection (WPI). On each date, three infected mice and two age-matched uninfected mice were sacrificed for serum collection and histological processing of the liver, lungs, musculature, and brain. Infectivity assessment by enzyme-linked immunosorbent assay (ELISA) revealed that the overall immunological pattern of infected mice tended to be towards the Th2 type response. Serum IgG1 antibody titers in infected mice were significantly higher than that of the uninfected control mice throughout the trial (P<0.05). On the other hand, no significant difference in titers of IgG3 antibody, an indicator for the Th1 type response, was observed between the infected and control mice, except at eight WPI (P<0.05). Pathogenicity was assessed semiquantitatively by comparing the mean number or diameter of inflammatory foci as well as histopathological changes in the liver, musculature, brain, or lungs of the infected mice and the control mice. Each hematoxylin and eosin (H&E) stained tissue section slide was examined under 100x magnification and 15 random fields were counted. Degree of inflammatory injury among the four organs was scored and categorized into four levels: normal (0), mild (1+), moderate (2+), and severe (3+). An index of inflammatory injury (mean score of experimental group/mean score of 10 control groups of 20 uninfected mice) of 2-3 is considered as moderate to severe, 1-2 as mild to moderate, and 0-1 as normal to mild. Histopathological changes were moderate to severe in the liver and lungs, mild to moderate in the musculature, and only normal to mild in the brain throughout the trial. It is noteworthy that apocrine-like change in epithelial cells of the bile duct was observed in most of the infected mice from eight WPI onward. Furthermore, larvae trapped by organized granulomas were found in soft tissue near the musculature at 12, 20, and 28 WPI. Altogether, not only were the infectivity and pathogenicity of the 14-month-cultured T. canis embryonated eggs retained, the hatched larvae were also capable of eliciting some special pathological changes in the murine host.

Intestinal nematodes and pulmonary tuberculosis

We report a significantly higher prevalence of intestinal nematodes in patients with pulmonary tuberculosis (TB) compared to a matched control group: 33/57 (57.8%) in patients with TB and 18/86 (20.9%) in the control group; OR = 5.19; 95% CI = 2.33-11.69; p = 0.000). When TB patients eosinophilia was also significantly higher among those with intestinal parasites (69.8%) compared to those without this condition (45.6%). We hypothesized that the immune modulation induced by nematodes is a factor that enhances TB infection/progression and that eosinophilia seen in TB patients is a consequence of helminth infection.

Nematode infections are risk factors for staphylococcal infection in children

Nematode infection may be a risk factor for pyogenic liver abscess in children and we hypothesized that the immunomodulation induced by those parasites would be a risk factor for any staphylococcal infection in children. The present study was designed to compare, within the same hospital, the frequency of intestinal nematodes and Toxocara infection in children with and without staphylococcal infections. From October 1997 to February 1998, 80 children with staphylococcal infection and 110 children with other diseases were submitted to fecal examination, serology for Toxocara sp., evaluation of plasma immunoglobulin levels, and eosinophil counts. Mean age, gender distribution, birthplace, and socioeconomic conditions did not differ significantly between the two groups. Frequency of intestinal nematodes and positive serology for Toxocara, were remarkably higher in children with staphylococcal infections than in the non-staphylococcal group. There was a significant correlation between intestinal nematodes or Toxocara infection and staphylococcal infection in children, reinforced by higher eosinophil counts and higher IgE levels in these children than in the control group. One possible explanation for this association would be the enhancement of bacterial infection by the immunomodulation induced by helminth infections, due to strong activation of the Th2 subset of lymphocytes by antigens from larvae and adult worms.

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.