Polymerase Chain Reaction: A Better Method for Diagnosing Chronic Schistosoma mansoni Infections.

For more effective diagnosis of the acute and chronic stages of Schistosoma mansoni infection in humans, the polymerase chain reaction (PCR) technique was compared with the Kato-Katz method. A total of 150 stool samples were collected from inpatient and outpatient clinics at the Department of Tropical Medicine, Minia University Hospital, Egypt. Three groups of patients, 50 with acute intestinal schistosomiasis, 70 with chronic intestinal schistosomiasis and 30 normal healthy controls were studied. Stool samples were analyzed by PCR and the Kato-Katz method. The mean number of eggs per gram of feces was 4.6 when estimated by the Kato-Katz method in positive stool samples from acute schistosomiasis cases but only 1.7 in chronic cases. In acute intestinal schistosomiasis, 15 and 45 out of 50 cases were positive by Kato-Katz and PCR, respectively. In the chronic intestinal schistosomiasis cases, 6 and 68 out of 70 cases were positive by the Kato-Katz and PCR methods, respectively. We conclude that PCR appears to be an effective diagnostic technique for S. mansoni infection, especially where a low worm burden exists, such as in chronic cases.

Breast-feeding protects infantile diarrhea caused by intestinal protozoan infections.

This study investigated the effect of breast-feeding in protection against protozoan infection in infants with persistent diarrhea. Infants were classified into 2 groups; 161 breast-fed infants and the same number of non-breast-fed infants. Microscopic examinations of stool were done for detection of parasites and measuring the intensity of infection. Moreover, serum levels of IgE and TNF-α were measured by ELISA. Cryptosporidium spp., Entamoeba histolytica/Entamoeba dispar, Giardia lamblia, and Blastocystis sp. were demonstrated in infants with persistent diarrhea. The percentage of protozoan infections was significantly lower in breast-fed infants than that in the non-breast-fed infants. The levels of IgE and TNF-α were significantly lower in the breast-fed group than in the non-breast-fed group. There were significant positive associations between the serum levels of IgE and TNF-α and the intensity of parasite infection in the breast-fed group. It is suggested that breast-feeding has an attenuating effect on the rate and intensity of parasite infection.

Cutaneous leishmaniasis in the Nalut District, Libyan Arab Jamahiriya: a clinico-epidemiologic study and Leishmania species identification.

Cutaneous leishmaniasis (CL), an endemic disease in the littoral zones of the Mediterranean area, the Middle East, East Africa, and especially in Libya, has not been fully documented. The present study clarifies the clinico-epidemiologic profile of CL and the molecular genotyping of the Leishmania spp. in the Nalut district, Libya. Two hundred and twenty-three CL patients were examined at the out-patient clinics of Nalut Hospital from March 2006 to February 2007. CL was diagnosed by clinical, microscopic, culture, polymerase chain reaction (PCR), and PCR-restriction fragment length polymorphism (RFLP) analyses. The disease was observed year-round, with the highest prevalence between November and February. Fifty-nine percent of patients were younger than 20 yr. Nodulo-ulcerative lesions, indurated ulcers, papulo-ulcerative lesions, and subcutaneous nodular lesions were observed in 170, 25, 15, and 13 patients, respectively. Two hundred patients (89.7%) had dry type of lesions, whereas 23 patients (10.3%) presented a wet type of lesion. One hundred and fifty-nine (71.3%) of 223 patients were confirmed positive for CL by the presence of the amastigote form of Leishmania by stained Giemsa smear, and 170 (76.2%) were positive according to the presence of the promastigote form of Leishmania by culture in RPMI 1640 medium supplemented with 10% fetal bovine serum (FBS). PCR confirmed 203 (91.0%) positive cases. Genotyping of Leishmania spp. by RFLP analysis revealed that L. tropica was the most common species at all ages, and L . infantum was second under 20 yr of age. In summary, CL is endemic in the Nalut district, Libya; PCR was the most sensitive parasite diagnostic test, and L. tropica was the most common species.

Transplantation of skin grafts and organs infected with Toxoplasma gondii as a source of toxoplasmosis in immunocompromised mice.

The possibility of Toxoplasma gondii infection resulting from transplantation of a skin graft and various organs has been investigated. The parasite was detected in very low numbers in all organs examined in wild-type (WT) BALB/c (B/c) mice that received skin grafts from infected interferon gamma knockout (GKO) B/c mice both with and without sulfamethoxazole treatment; all recipient mice survived. In contrast, transplantation of skin grafts from untreated infected WT B/c mice to naïve GKO B/c mice led to the death of all recipients within 20 days post-transplantation; T. gondii was found to be disseminated in all organs examined. Similar results were obtained after transplantation of skin from untreated and treated GKO B/c mice to naïve GKO B/c mice, whereas the recipient GKO B/c mice died within 10 days after intraperitoneal transplantation of lung, heart, brain or small intestine from infected untreated GKO B/c mice. These results indicate that skin grafts as well as various organs infected with T. gondii can be sources of infection in immunocompromised hosts. Toxoplasmosis should therefore be taken into consideration during organ transplantation to immunocompromised hosts.

In vivo study of toxoplasmic parasitemia using interferon-gamma-deficient mice: absolute cell number of leukocytes, parasite load and cell susceptibility.

Toxoplasma gondii infection was induced in wild type (WT) C57BL/6 and BALB/c mice and same-background interferon-gamma knockout (GKO) mice by peroral inoculation of Fukaya strain cysts. We studied parasitemia, absolute cell number of leukocytes, and cell susceptibility in peripheral blood leukocyte (PBL) subsets in vivo. Parasitemia was observed in both WT and GKO mice, although the pattern of the parasite load was totally different among them. After infection, the absolute number of neutrophils in peripheral blood increased in both GKO C57BL/6 and GKO BALB/c mice with statistical significance, while it rose up slightly in susceptible WT C57BL/6 mice, but declined moderately in resistant WT BALB/c mice. The absolute number of lymphocytes in both WT and GKO mice decreased significantly after infection. Although leukocyte number per mul decreased significantly in both strains of WT mice, it increased in GKO BALB/c mice. There were no differences in susceptibility of PBL subsets to T. gondii infection as assessed by quantitative competitive polymerase chain reaction in both WT and GKO mice. These results indicate that each of the PBL subsets was infected in vivo. The increase of neutrophils only among immunocompromised or susceptible strains suggests that the neutrophil may be involved in the lethal process of T. gondii infection. The lack of any difference in cell susceptibility per mug gDNA among the PBL subsets examined implies that the neutrophil may contribute to the whole body dissemination process of the parasite in vivo more than other PBL subsets through the increase in number.

A theoretical analysis of the relations between the risk of congenital toxoplasmosis and the annual infection rates with a convincing argument for better public intervention.

In a theoretical analysis of the present study, we quantitatively indicate a potential threat of congenital toxoplasmosis to Japanese young women by the use of a simple mathematical model or a special case of the well-known catalytic infection model. For introducing a risk function of congenital toxoplasmosis, an annual infection rate, r, was divided into r(1), the rate before age a(0 < a < 15), and r(2), the rate after age a. Presuming the values of r(1), r(2) and a on the basis of the current situation of Toxoplasma infection in Japan, simulation analyses were performed with the mathematical model. As the simulation clearly demonstrated, Japanese young women are potentially facing a threat of congenital toxoplasmosis, although the current risk of it is relatively lower. From the viewpoint of risk management, public intervention programs are required. Based on our analyses, public intervention programs can be classified into two groups: group 1 for women before age a and group 2 for those after age a, and each group is expected to give a different kind of effect to the risk of congenital toxoplasmosis. The present study implies that a certain public intervention program could augment the risk, inadvertently.