Trypanosoma cruzi infection associated with atypical clinical manifestation during the acute phase of the Chagas disease.

BACKGROUND: Chagas disease (CD) is caused by the protozoan parasite Trypanosoma cruzi and is transmitted by triatomine insects. Clinical manifestations vary according to the phase of the disease. Cutaneous manifestations are usually observed in the acute phase (chagoma and Romaña's sign) or after reactivation of the chronic phase by immunosuppression; however, a disseminated infection in the acute phase without immunosuppression has not been reported for CD. Here, we report an unusual case of disseminated cutaneous infection during the acute phase of CD in a Mexican woman. METHODS: Evaluation of the patient included a complete clinical history, a physical exam, and an exhaustive evaluation by laboratory tests, including ELISA, Western blot and PCR. RESULTS: Skin biopsies of a 50-year-old female revealed intracellular parasites affecting the lower extremities with lymphangitic spread in both legs. The PCR tests evaluated biopsy samples obtained from the lesions and blood samples, which showed a positive diagnosis for T. cruzi. Partial sequencing of the small subunit ribosomal DNA correlated with the genetic variant DTU II; however, serological tests were negative. CONCLUSIONS: We present a case of CD with disseminated skin lesions that was detected by PCR and showed negative serological results. In Mexico, an endemic CD area, there are no records of this type of manifestation, which demonstrates the ability of the parasite to initiate and maintain infections in atypical tissues .

Inherent biomechanical traits enable infective filariae to disseminate through collecting lymphatic vessels.

Filariases are diseases caused by arthropod-borne filaria nematodes. The related pathologies depend on the location of the infective larvae when their migration, the asymptomatic and least studied phase of the disease, comes to an end. To determine factors assisting in filariae dissemination, we image Litomosoides sigmodontis infective larvae during their escape from the skin. Burrowing through the dermis filariae exclusively enter pre-collecting lymphatics by mechanical disruption of their wall. Once inside collectors, their rapid and unidirectional movement towards the lymph node is supported by the morphology of lymphatic valves. In a microfluidic maze mimicking lymphatic vessels, filariae follow the direction of the flow, the first biomechanical factor capable of helminth guidance within the host. Finally, non-infective nematodes that rely on universal morpho-physiological cues alone also migrate through the dermis, and break in lymphatics, indicating that the ability to spread by the lymphatic route is an ancestral trait rather than acquired parasitic adaptation.

Tissue-specific immunopathology during malaria infection.

Systemic inflammation mediated by Plasmodium parasites is central to malaria disease and its complications. Plasmodium parasites reside in erythrocytes and can theoretically reach all host tissues via the circulation. However, actual interactions between parasitized erythrocytes and host tissues, along with the consequent damage and pathological changes, are limited locally to specific tissue sites. Such tissue specificity of the parasite can alter the outcome of malaria disease, determining whether acute or chronic complications occur. Here, we give an overview of the recent progress that has been made in understanding tissue-specific immunopathology during Plasmodium infection. As knowledge on tissue-specific host-parasite interactions accumulates, better treatment modalities and targets may emerge for intervention in malaria disease.

Mouse-Based Research on Quiescent Primate Malaria Parasites.

Mice engrafted with primate tissue make two important plasmodial dormancy-related questions researchable. The first is concerned with whether latent merozoites in the lymphatic system can give rise to relapse-like, recurrent malaria in primates. The second is that genetic evidence of hypnozoite activation as the source of relapsing primate malaria can be looked for.

Toxoplasma gondii dissemination: a parasite's journey through the infected host.

Toxoplasma gondii is a highly successful global pathogen that is remarkable in its ability to infect nearly any nucleated cell in any warm-blooded animal. Infection with T. gondii typically occurs through the ingestion of contaminated food or water, but the parasite then breaches the intestinal epithelial barrier and spreads from the lamina propria to a large variety of other organs in the body. A key feature of T. gondii pathogenesis is the parasite's ability to cross formidable biological barriers in the infected host and enter tissues such as the brain, eye and placenta. The dissemination of T. gondii into these organs underlies the severe disease that accompanies human toxoplasmosis. In this review, we will focus on seminal studies as well as exciting recent findings that have shaped our current understanding of the cellular and molecular mechanisms by which T. gondii journeys throughout the host and enters organs to cause disease.

Insights into the pathogenesis of disease in human lymphatic filariasis.

Although two thirds of the 120 million people infected with lymph-dwelling filarial parasites have subclinical infections, ∼40 million have lymphedema and/or other pathologic manifestations including hydroceles (and other forms of urogenital disease), episodic adenolymphangitis, lymphedema, and (in its most severe form) elephantiasis. Adult filarial worms reside in the lymphatics and lymph nodes and induce lymphatic dilatation. Progressive lymphatic damage and pathology results primarily from the host inflammatory response to the parasites but also perhaps from the host inflammatory response to the parasite's Wolbachia endosymbiont and as a consequence of superimposed bacterial or fungal infections. This review will attempt to shed light on disease pathogenesis in lymphatic filariasis.

Brugia pahangi: immunization with early L3 ES alters parasite migration, and reduces microfilaremia and lymphatic lesion formation in gerbils (Meriones unguiculatus).

Previous studies have shown that intradermally (ID) injected Brugia pahangi L3 s migrate through various tissues and into the lymphatics of gerbils in a distinct pattern. Excretory/secretory products (ES) produced at the time of invasion of B. pahangi are likely to be important in this early migration phase of the parasite life cycle in their rodent host. Hence, early L3 ES was collected from 24h in vitro cultures of B. pahangi L3 larvae and used in immunization experiments to investigate the effect of immunity to early L3 ES on worm migration, survival and development of B. pahangi. Immunization of gerbils with ES in RIBI adjuvant produced antibodies to numerous ES proteins eliciting a strong humoral response to ES and indirect fluorescent antibody (IFA) assay using anti-ES serum recognized the ES proteins on the surface of B. pahangi L3 larvae. Following ES immunization, gerbils were challenged either ID or intraperitoneally (IP) with 100 L3 s of B. pahangi and euthanized at 3 or 106 days post inoculation (DPI). Immunization with early ES slowed the migration of ID inoculated L3 at 3 DPI and significantly altered the locations of adult worms at 106 DPI. Immunization did not induce protection in any treatment group. However, immunized animals had significantly fewer microfilariae per female worm suggesting the antigens in ES are important in microfilariae development or survival in the host. The number of lymphatic granulomas was also significantly reduced in ES immunized animals. It is important to note that microfilariae serve as a nidus in these granulomas. Our results shows immunization with early Brugia malayi L3 ES alters the worm migration, affects circulating microfilarial numbers and reduces lymphatic granulomas associated with B. pahangi infection in gerbils.

Lymphatic filariasis: perspectives on lymphatic remodeling and contractile dysfunction in filarial disease pathogenesis.

Lymphatic filariasis, one of the most debilitating diseases associated with the lymphatic system, affects over a hundred million people worldwide and manifests itself in a variety of severe clinical pathologies. The filarial parasites specifically target the lymphatics and impair lymph flow, which is critical for the normal functions of the lymphatic system in maintenance of body fluid balance and physiological interstitial fluid transport. The resultant contractile dysfunction of the lymphatics causes fluid accumulation and lymphedema, one of the major pathologies associated with filarial infection. In this review, we take a closer look at the contractile mechanisms of the lymphatics, its altered functions, and remodeling during an inflammatory state and how it relates to the severe pathogenesis underlying a filarial infection. We further elaborate on the complex host-parasite interactions, and molecular mechanisms contributing to the disease pathogenesis. The overall emphasis is on elucidating some of the emerging concepts and new directions that aim to harness the process of lymphangiogenesis or enhance contractility in a dysfunctional lymphatics, thereby restoring the fluid imbalance and mitigating the pathological conditions of lymphatic filariasis.

Filarial lymphatic pathology reflects augmented toll-like receptor-mediated, mitogen-activated protein kinase-mediated proinflammatory cytokine production.

Lymphatic filariasis can be associated with the development of serious pathology in the form of lymphedema, hydrocele, and elephantiasis in a subset of infected patients. Toll-like receptors (TLRs) are thought to play a major role in the development of filarial pathology. To elucidate the role of TLRs in the development of lymphatic pathology, we examined cytokine responses to different Toll ligands in patients with chronic lymphatic pathology (CP), infected patients with subclinical pathology (INF), and uninfected, endemic-normal (EN) individuals. TLR2, -7, and -9 ligands induced significantly elevated production of Th1 and other proinflammatory cytokines in CP patients in comparison to both INF and EN patients. TLR adaptor expression was not significantly different among the groups; however, both TLR2 and TLR9 ligands induced significantly higher levels of phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein (MAP) kinases (MAPK) as well as increased activation of NF-κB in CP individuals. Pharmacologic inhibition of both ERK1/2 and p38 MAP kinase pathways resulted in significantly diminished production of proinflammatory cytokines in CP individuals. Our data, therefore, strongly suggest an important role for TLR2- and TLR9-mediated proinflammatory cytokine induction and activation of both the MAPK and NF-κB pathways in the development of pathology in human lymphatic filariasis.

Filariasis: diagnosis, treatment and prevention.

Lymphatic filariasis caused by the mosquitoborne, lymphatic-dwelling nematodes Wuchereria bancrofti and Brigia malayi is still a common tropical parasitic disease and 120 million people are affected in the world, of which two-third in Asia. W. bancrofti is responsible for 90% of this disease, while B. malayi for the remaining 10%. Next to psychiatric illness, this is the leading cause for permanent and long-term disability. Some recent studies have evidenced new aspects in the diagnosis, management and in planning effective strategies for its global prevention. The aim of this up to date is to evidence clinical, diagnostic and therapeutic aspects of this very important infection.

Sex ratio of Wuchereria bancrofti in surgical specimens from an endemic area of Brazil.

The sex ratio of adult Wuchereria bancrofti from 172 histologically diagnosed cases of lymphatic filariasis, all from an endemic area of Recife, in north-eastern Brazil, was investigated. Of 172 tissue specimens examined, 74 (43%) were lymph nodes and 98 (57%) lymphatic-vessel segments. The morphology of the worms was generally disrupted, in some cases to the point where the worms were almost completely absorbed by the granulomatous inflammatory response. Parasite gender was clearly determined in only 110 (64%) specimens, 61 (55.5 %) of which were lymph nodes and 49 (44.5%) lymphatic vessels. Eighty-seven (79.1%) of these tissue specimens contained only female worms, 17 (14.5%) both males and females, and six only males, giving an overall female:male 'specimen' ratio of 4.5:1. Of the 63 tissue specimens in which dead or degenerating worms were noted, 60 (92.2%) contained only females. All the female worms detected were gravid, regardless of whether male worms were present in the specimen. The implications of these findings for parasite dynamics, the pathogenesis of bancroftian filariasis and the interpretation of ultrasound images of living adult worms are discussed.

Molecular cloning, purification and characterisation of myosin of human lymphatic filarial parasite Brugia malayi.

Global efforts have been made towards development of vaccine for prevention of lymphatic filariasis. However, lack of thorough knowledge about developmental biology and pathogenesis of filarial parasite restricts us from developing an effective vaccine. A limited number of immunodominant antigens of human lymphatic filariid Brugia malayi have been characterised; however, none of these recombinant antigens so far induced significant degree of protective immunity to challenge infection. In the present study, we identified a approximately 2.0 Kb cDNA clone by immunoscreening of cDNA library of adult female Brugia malayi. The nucleotide sequence of the identified clone showed 94.3% homology with C-terminal part of myosin heavy chain gene of Brugia malayi. This cDNA insert was sub-cloned into pET28b vector and expressed in BL21(DE3). The recombinant protein was purified to near homogeneity by immobilised metal affinity chromatography (IMAC) with yield of approximately 25 mg/l. The purified protein was recognised in western blot with anti-His tag antibody as also with the antibodies present in the sera of human W. bancrofti patients of all categories and infected/immunized rodent serum demonstrating its functional role. Recombinant myosin induced marked cellular immune response as observed by lymphoproliferation assay. The present findings demonstrate the usefulness of B. malayi recombinant myosin as vaccine candidate against human lymphatic filariasis.

Wuchereria bancrofti: effect of single and multiple larval inoculations on infection dynamics and development of clinical manifestations in non-human primate Presbytis entellus.

We earlier reported the successful experimental transmission of Wuchereria bancrofti from humans to the Indian leaf monkey (Presbytis entellus) [Misra, S., Tyagi, K., Chatterjee, R.K., 1997. Experimental transmission of nocturnally periodic Wuchereria bancrofti to Indian leaf monkey (Presbytis entellus). Experimental Parasitology 86,155-157.; Dube, A., Murthy, P.K., Puri, S.K., Misra-Bhattacharya, S., 2004. Presbytis entellus: a primate model for parasitic disease research. Trends in Parasitology 20(8), 358-360.] using a small number of animals. The present study, involving 27 langur monkeys, found the development of pathological manifestations ranging from filarial fever, lymphangitis, lymphadenitis, hydrocoele, and limb edema to minor histopathological changes in tissues after single, double, triple, or multiple inoculations of infective larvae of W. bancrofti recovered from Culex quinquefasciatus fed on human microfilaraemic blood. Thirty-eight percent of the infected langurs developed detectable microfilaraemia in their blood. Single or double larval exposure resulted in better worm establishment than multiple exposures with small numbers of larvae. All of the langurs receiving a single large inoculum and 85.71% of those receiving two inoculations harbored adult parasites. Worm establishment decreased with increasing number of larval inoculations. In all, 60% of infected langurs developed classical gross-pathological symptoms of lymphatic filariasis. Of these, 29.16% developed thickening of the lymphatics, 25% suffered from periodic rise in rectal temperature, and 16.66% developed scrotal swelling with presence of microfilariae in the hydrocoele fluid. Only one out of 25 langurs (4%) developed acute limb edema. It appeared that a single inoculum of a large number of infective larvae was able to induce maximum pathology. Fifty-six percent of the infected langurs acquired a peculiar sitting posture, retracting both the hind limbs, usually after 4-5 months of larval inoculation and eventually resulting in reduced mobility. Oral administration of diethylcarbamazine (citrate) at 12mg/kg for 12 consecutive days to one langur caused 80% suppression in microfilaraemia on day 8, killing all the adult parasites. Of the two immunosuppressed (cortisone- or prednisolone-treated) male rhesus monkeys included in the study, neither developed any of the above lymphatic symptoms or parasites after receiving larval inoculations on two or three occasions; however, a rise in rectal temperature in one of the animals was noticed. The present study thus reveals that the Indian leaf monkey, P. entellus, may serve as an ideal non-human primate model of human bancroftian filariasis for carrying out longitudinal studies on pathology, host-parasite interactions, and preclinical evaluation of candidate anti-filarial drugs or vaccines.

Haematogenous dissemination of Leishmania (Viannia) braziliensis in human American tegumentary leishmaniasis.

One of the potential dangers of American tegumentary leishmaniasis (ATL) caused by Leishmania (Viannia) braziliensis is the development of mucosal lesions. Haematogenous dissemination of the parasite is the most likely mechanism to explain this occurrence, but most attempts to isolate the parasite from blood have so far been unsuccessful. The presence of Leishmania in peripheral blood was therefore evaluated by PCR using DNA samples isolated from patients presenting active cutaneous or mucosal disease, and from individuals cured by antimonial treatment as well as individuals without a past history of leishmaniasis but with a positive Montenegro skin test, all living in L. (V.) braziliensis-endemic areas. Leishmania DNA was found not only in those patients presenting active cutaneous (24.8%) or mucosal (35%) lesions, but also in samples isolated from healed individuals (27.3%) as well as in asymptomatic skin-test-positive residents of endemic areas (37.5%). Overall, PCR showed the presence of parasite DNA in the blood of 26.2% of the 225 examined samples. These data suggest that persistence of parasites within the host may last for many years and, rather than being a risk factor, might be important in maintaining the protective response in those living in endemic areas.

Ultrasonographic examination of Haitian children with lymphatic filariasis: a longitudinal assessment in the context of antifilarial drug treatment.

To assess the clinical findings associated with detection of adult Wuchereria bancrofti worms on ultrasound, 186 schoolchildren in a filariasis-endemic area of Haiti underwent physical and ultrasonographic examinations. The filaria dance sign (FDS) of adult W. bancrofti was detected in the inguinal and crural lymphatics of 28 (15%) children. FDS detection was more common in older children (P = 0.003) and in those with a history of inguinal lymph node inflammation (P = 0.002) or crural lymphadenopathy on physical exam (P = 0.01). Twenty-five FDS-positive children were reexamined after three annual cycles of mass treatment for lymphatic filariasis (LF). The total number of adult worm nests detected by ultrasound decreased from 29 to 4 (P

Cellular immune response to parasite infection in the Drosophila lymph gland is developmentally regulated.

The mechanisms by which an organism becomes immune competent during its development are largely unknown. When infected by eggs of parasitic wasps, Drosophila larvae mount a complex cellular immune reaction in which specialized host blood cells, lamellocytes and crystal cells, are activated and recruited to build a capsule around the parasite egg to block its development. Here, we report that parasitization by the wasp Leptopilina boulardi leads to a dramatic increase in the number of both lamellocytes and crystal cells in the Drosophila larval lymph gland. Furthermore, a limited burst of mitosis follows shortly after infection, suggesting that both cell division and differentiation of lymph gland hemocytes are required for encapsulation. These changes, observed in the lymph glands of third-instar, but never of second-instar hosts, are almost always accompanied by dispersal of the anterior lobes themselves. To confirm a link between host development and immune competence, we infected mutant hosts in which development is blocked during larval or late larval stages. We found that, in genetic backgrounds where ecdysone levels are low (ecdysoneless) or ecdysone signaling is blocked (nonpupariating allele of the transcription factor broad), the encapsulation response is severely compromised. In the third-instar ecdysoneless hosts, postinfection mitotic amplification in the lymph glands is absent and there is a reduction in crystal cell maturation and postinfection circulating lamellocyte concentration. These results suggest that an ecdysone-activated pathway potentiates precursors of effector cell types to respond to parasitization by proliferation and differentiation. We propose that, by affecting a specific pool of hematopoietic precursors, this pathway thus confers immune capacity to third-instar larvae.

Fine structure of intrascrotal lymphatic vessels infected by Wuchereria bancrofti adult worms.

Lymphangiectasia represents a basic phenomenon of acute and chronic pathology in lymphatic filariasis, and the prevalence or degree of lymphatic dilation caused by filarial worms is considered an indirect measurement of the altered lymphatic function. We examined the morphological alterations of intrascrotal lymphatic vessels surgically removed from a volunteer infected by adult worms of Wuchereria bancrofti. Scanning electron microscopy revealed lymphatic vessels with an irregular endothelium and adherent flattened lymphocytes and macrophages in variable proportions. On transmission electron microscopy the lymphatic vessels showed a thin endothelium which had an irregular contour and projected several cytoplasmic processes into the lumen. Numerous micropinocytotic vesicles and collagen fibers were abundant and disorganized. The hyperplastic endothelial cells and the subendothelial fibrosis suggest that abnormal changes in these cells may play a crucial role in the development of lymphangiectasia.