Sumeeta Khurana

Association of parasitic infections and cancers.

Recent advances in the fields of molecular biology, epidemiology and infectious diseases have led to significant revelations to clarify the relationship between cancer and infective agents. This article reviews the relationship between parasitic infections and carcinogenesis and the possible mechanisms involved. Few parasites, e.g., Schistosoma haematobium and Opisthorchis viverrini have been found to be strongly associated with bladder cancer and cholangiocarcinoma respectively. The evidence for the association of several other parasites and cancers has also been postulated.

Genetic diversity of Cryptosporidium isolates from patients in North India

BACKGROUND Cryptosporidiosis is a significant cause of diarrheal illness in both immunocompetent and immunocompromised populations. Cryptosporidium species infect a wide range of hosts including humans. Different species are morphologically indistinguishable, and molecular techniques have become the key to detection and source tracking. The present study was designed to study the genetic diversity of human Cryptosporidium isolates in North India. METHODS Cryptosporidium oocysts were detected in stool samples by special staining of fecal smears. DNA was extracted with a Qiagen kit and all samples were genotyped by small subunit ribosomal ribonucleic acid (SSU rRNA)-based nested PCR-restriction fragment length polymorphism (RFLP) tool using enzymes SspI and VspI. Cryptosporidium hominis and Cryptosporidium parvum isolates were subtyped by sequence analysis of the nested PCR amplified gp60 gene. RESULTS Fifty-three fecal samples were found to be positive for Cryptosporidium oocysts. RFLP analysis revealed 39 isolates as C. hominis and 13 isolates of C. parvum; one sample failed amplification. gp60-based sequencing of C. hominis and C. parvum divided them into eight subgenotype families and 17 subtypes. gp60-based sequencing identified seven cases of mixed infection with C. hominis and C. parvum/Cryptosporidium meleagridis and showed the presence of C. meleagridis in six HIV-positive patients that were indistinguishable in RFLP. CONCLUSIONS Cryptosporidium isolates obtained in the present study from patients in North India belonged to three species, eight subgenotype families, and 17 subtypes. The existence of many Cryptosporidium species, subgenotypes, and subtypes along with mixed infections reveals the complexity of Cryptosporidium transmission; this heterogeneity indicates stable cryptosporidiosis transmission in North India. The results may have further implications in understanding the epidemiology and control of this infection.

Evaluation of Ziehl-Neelsen staining, auramine phenol staining, antigen detection enzyme linked immunosorbent assay and polymerase chain reaction, for the diagnosis of intestinal cryptosporidiosis

Background and Objectives: Cryptosporidiosis is a very important opportunistic infection and is responsible for significant morbidity and mortality in HIV/AIDS patients. The objective of this study is to evaluate Ziehl-Neelsen staining, auramine phenol staining, antigen detection enzyme linked immunosorbent assay and polymerase chain reaction, for the diagnosis of intestinal cryptosporidiosis. Materials and Methods: The study was designed to determine the efficacy of modified Ziehl-Neelsen (ZN), Auramine-Phenol (AP) staining, antigen detection enzyme linked immunosorbent assay (ELISA) and nested polymerase chain reaction (PCR) for detection of cryptosporidia in 671 HIV-seropositive patients, 353 HIV-seronegative patients including 198 children with diarrhea and 50 apparently healthy adults. Results: Cryptosporidium was detected in 26 (3.9%), 37 (5.5%), 32 (4.8%) and 40 (6%) HIV-seropositive and 8 (2.3%), 10 (2.9%), 9 (2.6%) and 9 (2.6%) HIV-seronegative patients by ZN staining, AP staining, antigen detection ELISA and PCR, respectively. None of the healthy controls were infected with Cryptosporidium. Based on criteria of ′true positive′ samples, i.e. positive by any two of the four techniques out of ZN, AP, antigen detection ELISA and PCR, sensitivity of ZN and ELISA was 79.06% and 95.35% respectively. AP and PCR were found to be 100% sensitive. Specificity of ZN and ELISA was 100% while specificity of AP and PCR was 99.59% and 99.39% respectively. Conclusions: Auramine phenol staining is a rapid, sensitive and specific technique for diagnosis of intestinal cryptosporidiosis.

Serological screening for antenatal toxoplasma infection in India

PURPOSE Detection of infection caused by Toxoplasma gondii during pregnancy to prevent congenital infection. MATERIALS AND METHODS This study was carried out from January 2005 to 2006 in 300 pregnant women. Antitoxoplasma IgG, IgM, IgA antibody and IgG avidity were assessed using ELISA. At least two samples were taken at least 3 weeks apart preferably one in each trimester. RESULT Of these 300 pregnant women, anti toxoplasma IgG antibodies were detected in 46 (15.33%) cases, while 9 (3%) had positive anti toxoplasma IgM with IgA and /low IgG avidity antibodies suggestive of acute infection during or just before pregnancy. CONCLUSION The results indicate that about 85% of female population of Chandigarh is susceptible to toxoplasma infection and thus should be specifically educated about prevention of this infection during pregnancy.

Antitrichomonas IgG, IgM, IgA, and IgG subclass responses in human intravaginal trichomoniasis

Trichomoniasis, caused by the protozoan parasite Trichomonas vaginalis, is a major nonviral sexually transmitted disease. Clinical spectrum varies from an asymptomatic state to mild, moderate, or severe symptoms. However, the exact factors leading to the variations in symptoms have not been well elucidated. Host’s immune response to the parasite may be playing a role in varied symptomatology. The present study reports antitrichomonas IgM, IgA, IgG and its subclasses in doubling dilutions of serum and diluted vaginal washes of six T. vaginalis-infected symptomatic and four T. vaginalis-infected asymptomatic women and uninfected controls by enzyme-linked immunosorbent assay (ELISA). No significant difference was observed in serum IgG ELISA absorbance values from symptomatic compared to asymptomatic subjects (p > 0.05) while a significant difference (p < 0.05) was noted in serum IgM in all the tested dilutions and IgA up to a dilution of 400. This is the first report of the detection of specific IgG subclass response in T. vaginalis-infected female patients, and quantitative analysis of the antibody responses indicated that the production of local IgG particularly IgG1 in vaginal secretions may be playing a significant role in establishing symptomatic infection. The interesting observation of the present study is that the specific IgM was detected in 2 (33.3%) symptomatic and T. vaginalis-infected patients in ≥800 dilutions and in 1 (16.6%) up to 200 dilutions in serum, while it was not detectable in the vaginal secretions of symptomatic patients or in the serum and vaginal secretions of asymptomatic T. vaginalis-infected patients.

Human subcutaneous dirofilariasis in India: A report of three cases with brief review of literature

Human subcutaneous dirofilariasis is a rare infection caused by filarial worms of the genus Dirofilaria. The parasites are transmitted to man by mosquitoes and the infection is manifested as subcutaneous nodules. Excision of the lesion is both diagnostic and therapeutic. Hereby we report three cases of human subcutaneous dirofilariasis. The worms were sent to our department for identification over a period of four years (2006-2009). Of these three patients, two men and one woman were between 15 and 45 years of age. In two cases, the infection manifested as a nodule on face, in one case near lower eyelid and in the other on the cheek, while in the third case as an itchy nodule on the abdomen. It is emphasized that both clinicians and microbiologists should have an increased awareness of this entity and include dirofilariasis in the differential diagnosis of patients presenting with subcutaneous nodules.

Intestinal microsporidiosis in India: A two year study.

Intestinal parasitic pathogens in HIV/AIDS patients include Cryptosporidium sp, Cystoisospora sp, microsporidia and less commonly other parasites. The two most common microsporidia causing intestinal infection are Enterocytozoon bieneusi and Encephalitozoon intestinalis. Most of the Indian studies for intestinal parasitic infections in HIV/AIDS patients have not included microsporidia, due to difficult staining and identification of the parasite. The aim of the present study was to find the prevalence of intestinal microsporidiosis and their species identification along with correlation of CD4 count with parasite positivity and diarrhoea in HIV positive individuals. Stool samples of 363 individuals including 125 HIV seropositive patients with diarrhoea, 158 HIV seropositive patients without diarrhoea, 55 HIV seronegative patients with diarrhoea and 25 healthy controls were obtained from various out-patient departments and in-patients admitted to a tertiary care hospital from August 2008 to October 2009. The stool samples were subjected to examination by wet mount, modified acid fast stain for coccidian parasites and multiplex nested PCR for microsporidia. The overall prevalence of all intestinal parasites among HIV patients in our study was 26.5%. The prevalence of intestinal parasitic pathogens in HIV positive patients with diarrhoea was 43.2%. Microsporidia were the most common parasites detected (14%) in all patients, while in HIV infected patients 15.9% patients had microsporidia infection. The most common species causing intestinal microsporidiosis in our study was E. intestinalis (10.5%). In HIV seropositive individuals with diarrhoea, E. intestinalis was 20.8% and E. bieneusi 8.0% while in HIV-seropositive individuals without diarrhoea, E. intestinalis was 3.8% and E. bieneusi 1.9%. E. intestinalis was present in 10.9% of HIV negative individuals with diarrhoea in whom E. bieneusi was not found. There was a significant association between CD4 count ≤200/μl and intestinal parasite positivity. Thus, it can be concluded that intestinal microsporidiosis is under reported but an important disease in India. The predominant species in our study is E. intestinalis , in contrast to other parts of the world where E. bieneusi is more common.

Ophthalmomyiasis: Three cases from North India

Three cases of external ophthalmomyiasis are reported here. The larvae were identified to be Oestrus ovis in two cases and Cochliomyia hominivorax in one. Two of the patients were immunocompetent while one was undergoing treatment for squamous cell carcinoma of eyelid. In the latter myiasis led to complete destruction of the eye.

Serum immunoglobulin G, M and A response to Cryptosporidium parvum in Cryptosporidium-HIV co-infected patients

BackgroundCryptosporidium parvum, the protozoan parasite, causes a significant enteric disease in immunocompromised hosts such as HIV patients. The present study was aimed to compare serum IgG, IgM and IgA responses to crude soluble antigen of C. parvum in HIV seropositive and seronegative patients co-infected with Cryptosporidium and to correlate the responses with symptomatology.MethodsCryptosporidium parvum specific serum antibody (IgG, IgM and IgA) responses were assessed by ELISA in 11 HIV seropositive Cryptosporidium positive (Group I), 20 HIV seropositive Cryptosporidium negative (Group II), 10 HIV seronegative Cryptosporidium positive (Group III), 20 HIV seronegative Cryptosporidium negative healthy individuals (Group IV) and 25 patients with other parasitic diseases (Group V).ResultsA positive IgG and IgA antibody response was observed in significantly higher number of Cryptosporidium infected individuals (Gp I and III) compared to Cryptosporidium un-infected individuals (Gp II, IV and V) irrespective of HIV/immune status. Sensitivity of IgG ELISA in our study was found to be higher as compared to IgM and IgA ELISA. The number of patients with positive IgG, IgM and IgA response was not significantly different in HIV seropositive Cryptosporidium positive patients with diarrhoea when compared to patients without diarrhoea and in patients with CD4 counts <200 when compared to patients with CD4 counts >200 cells/μl.ConclusionThe study showed specific serum IgG and IgA production in patients infected with Cryptosporidium, both HIV seropositive and seronegative as compared to uninfected subjects suggesting induction of Cryptosporidium specific humoral immune response in infected subjects. However, there was no difference in number of patients with positive response in HIV seropositive or seronegative groups indicating that HIV status may not be playing significant role in modulation of Cryptosporidium specific antibody responses. The number of patients with positive IgG, IgM and IgA response was not significantly different in patients with or without history of diarrhoea thereby indicating that Cryptosporidium specific antibody responses may not be necessarily associated with protection from symptomatology.

Comparison of staining techniques and multiplex nested PCR for diagnosis of intestinal microsporidiosis

Microsporidiosis is increasingly being recognized as the cause for diarrhea in immunocompromised patients. The 2 most common microsporidia causing gastrointestinal infection worldwide are Enterocytozoon bieneusi and Encephalitozoon intestinalis. The aim of present study was to evaluate different techniques for detection of intestinal microsporidia in human stool samples. The fecal samples of 395 individuals including 125 HIV-seropositive patients with diarrhoea, 158 HIV-seropositive patients without diarrhoea, 55 HIV-seronegative patients with diarrhoea, and 57 healthy controls were used for detection of microsporidia by modified trichrome staining, calcofluor staining, and multiplex polymerase chain reaction (PCR). PCR had the highest sensitivity of 100%, while its specificity was 97.9%. Trichrome staining had highest specificity of 100% but a sensitivity of 63.8% only, and calcofluor white had a sensitivity and specificity of 79.7% and 82.2%, respectively. Thus, for diagnosis of intestinal microsporidiosis, it is important to perform PCR as staining techniques are not good enough to detect microsporidia in stool samples and for their species identification.