Malaria on the Amazonian frontier: transmission dynamics, risk factors, spatial distribution, and prospects for control

Little follow-up data on malaria transmission in communities originating from frontier settlements in Amazonia are available. Here we describe a cohort study in a frontier settlement in Acre, Brazil, where 509 subjects contributed 489.7 person-years of follow-up. The association between malaria morbidity during the follow-up and individual, household, and spatial covariates was explored with mixed-effects logistic regression models and spatial analysis. Incidence rates for Plasmodium vivax and Plasmodium falciparum malaria were 30.0/100 and 16.3/100 person-years at risk, respectively. Malaria morbidity was strongly associated with land clearing and farming, and decreased after five years of residence in the area, suggesting that clinical immunity develops among subjects exposed to low malaria endemicity. Significant spatial clustering of malaria was observed in the areas of most recent occupation, indicating that the continuous influx of nonimmune settlers to forest-fringe areas perpetuates the cycle of environmental change and colonization that favors malaria transmission in rural Amazonia.     

Prevalence of toxocariasis in rural and urban areas

The prevalence of toxocariasis was studied among different age groups of the population in eight municipal entities of the Sverdlovsk Region. Since 1995, the number of infected patients was shown to have annually increased by 1.4-2 times and amounted to 2.9 per 100,000. The 2003 serological surveys indicated that Toxocara antibodies were found in 8.9% of the children examined in different areas of the region. The epidemic process more actively involved rural children. Numerous tests for Toxocara eggs were more positive in the cities and towns with every amenity than in rural areas. Serodiagnostic tests demonstrated that children aged 3-6 and 7-14 years were involved into the epidemic process. The similar data were obtained in different age groups of adults. Nevertheless, among the adult population, the number of adult seropositive persons was significantly 1.9 times higher than that of children, which may reflect certain regularities in the formation of an immune stratum. The titers of serum Toxocara antibodies, being 1:800 or higher, may suggest that more than 50% of the total number of the examinees might be, in terms of clinical signs, patients with toxocariasis.     

Epidemiological aspects and risk factors of toxocariasis in a pediatric population in Sri Lanka

This cross-sectional study, carried out over a period of 11 months, investigated the relationship between Toxocara seropositivity, socio-demographic and environmental variables in a pediatric population. Risk factors for Toxocara infection were assessed by direct interview of parent or guardian using a structured pre-tested questionnaire. Eosinophilia and presence of helminth eggs or protozoan cysts in a fecal smear were recorded. Diagnosis of Toxocara seropositivity in children was based on IgG Toxocara Microwell Serum Elisa Kits. The ELISA test was regarded as positive if the optical density was 0.3 units or above. Unadjusted and adjusted odds ratios were calculated to determine risk factors for disease. The proportion of children who were positive for Toxocara antibodies in the study population was 20%. Children being exposed to a puppy of less than 3 months at home, visiting a playground frequently, living in a poorly constructed house and dogs having access to playgrounds were significant risk factors on univariate analysis. Of these four variables, only the first three variables (OR 19, OR 4 and OR 3, respectively) remained significant risk factors on the multivariate model. Presence of eosinophilia in seropositive children was significantly higher than the seronegative group (77% vs 40%; p < 0.001). This study indicates that dogs contribute significantly to children being seropositive for toxocariasis in Sri Lanka. Implementation of public health programs specifically focused on anti-parasitic treatment of dogs is recommended.     

Hepatitis A seroprevalence in children and young adults in Istanbul, Turkey: seroprevalence change and associated factors

Hepatitis A is a widespread infectious disease. The prevalence of the disease is closely related to socioeconomic status (SES) and environmental factors. Understanding its prevalence is essential for instituting appropriate precautions. The aim of this study was to determine the prevalence of hepatitis A and evaluate the associated demographic features in children and young adults in Istanbul. In total, 630 individuals between the ages of 5-24 were included in the study. They were classified into four age groups (5-9, 10-14, 15-19 and 20-24 years). The seropositivity of hepatitis A in the whole study population was 40%. Age-specific prevalence was 11.4% in children 5-9 years old, 29% in those 10-14 years old, 49.7% in those 15-19 years old and 69% in those 20-25 years old. Seropositivity was associated with increasing age, low SES, large family size, low maternal educational level, use of unsafe drinking water and living in regions with poor infrastructure and incomplete urbanization. When we compared our results with previous seroprevalence studies performed in Istanbul, we found an epidemiological shift towards increasing age. Factors associated with changes in prevalence were urbanization and associated infrastructure improvement, knowledge of the disease by the population, use of good hygiene and use of vaccination in those at high risk.     

National seroprevalence and risk factors for Zoonotic Toxocara spp. infection

To estimate the prevalence of Toxocara spp. infection in a representative sample of the United States population >or= 6 years of age, sera from participants in the Third National Health and Nutrition Examination Survey (1988-1994) were tested for antibodies to Toxocara. Among the 30,930 persons selected for the survey, 82% (N = 25,733) were interviewed, and 91% (N = 23,527) of those interviewed underwent physical examination of which 87% (N = 20,395) were tested. The age adjusted Toxocara seroprevalence was 13.9% (95% confidence intervals [CI] 12.5, 15.3), and was higher in non-Hispanic blacks (21.2%) than non-Hispanic whites (12%) or Mexican Americans (10.7%; P < 0.001). Increased Toxocara seropositivity was associated with head of household level of education (low versus high) (odds ratio [OR]: 2.2; CI: 1.8, 2.8), poverty (OR: 1.5; CI: 1.3, 1.8), elevated blood lead concentrations (OR: 1.4; CI: 1.1, 1.9), and dog ownership (OR: 1.2; CI: 1.1, 1.4). Toxocara infection is widespread and associated with specific risk groups.     

Hepatitis C and hepatitis B seroprevalence and associated risk factors in hemodialysis patients in Guilan province, north of Iran: HCV and HBV seroprevalence in hemodialysis patients

Background

Hepatitis C virus (HCV) and hepatitis B virus (HBV) infection are especially problematic in patients with end-stage renal disease who are undergoing hemodialysis (HD).

Objectives

To determine the prevalence of HCV and HBV infection in HD population in Guilan, north of Iran.

Patients and Methods

In a cross-sectional study, from May to September 2009, in 11 different hemodialysis units in Guilan province, North of Iran, clinical data such as age, gender, duration of dialysis, HBsAg and anti-HCV antibody of 514 HD patients were recorded. Patients with positive antibodies against HCV were tested for HCV RNA.

Results

From 514 patients, 286 (55.64%) were male. 61 (11.9%) patients were anti-HCV-positive and 31 (50.8%) were HCV PCR-positive. There was significant relationship between HCV Ab-positivity with gender and HD duration (p < 0.05). There was significant difference between the mean HD duration in anti-HCV-positive and anti-HCV-negative patients (p < 0.05). Also, significant relationship was found between HCV RNA-positivity with gender and HD duration (p < 0.05). Seven (1.4%) patients were positive for HBsAg. Two (0.38 %) were found positive for both HBsAg and anti-HCV antibody.

Conclusions

There is low a prevalence of HCV and HBV in HD patients in our region. The rate can be decreased by HBV vaccination of end-stage renal disease patients before setting chronic HD, antiviral treatment and isolation of infected individuals.     

A seroepidemiological study of toxocariasis and risk factors for infection in children in Sri Lanka

A seroepidemiology study using TES-ELISA was carried out in 1,020 children aged 1-12 years in the Hindagala Community Health Project, Sri Lanka. Toxocariasis seroprevalence was 43% with 16.6% showing high antibody levels. Unconditional logistic regression analysis showed 7-9 year olds to be at the highest risk (OR 3.0820; CI = 1.95-4.87). Dog ownership, especially puppies (OR 29.28; CI = 7.40-116.0), and geophagia-pica (OR 6.3732; CI = 3.87-10.50), were significant risk factors. Family clustering of toxocariasis was significant (chi2 = 88.000; p = 0.0001). Abdominal pain (45%), cough (30%), limb pain (23%) and skin rashes (20%) were significantly associated with seropositivity indicating that toxocariasis causes covert morbidity. These findings are, overall, applicable to other areas in Sri Lanka. However, in the dry zone, survival of infective eggs in the soil could be affected by the climate while more importantly, in agricultural areas with a high buffalo population, Toxocara vitulorum could account for human toxocariasis. Using a species specific double sandwich ELISA based on 57 kDa protein of T. canis ES antigen, it is demonstrated that 91% of the seropositives were due to T. canis. Thus along with rabies and dirofilariasis, toxocariasis is an important zoonotic health hazard from dogs in Sri Lanka and prevention is indicated.     

Human herpesvirus 8: seroprevalence and correlates in prostitutes in Mombasa,Kenya

Human herpesvirus 8 (HHV-8) infection is very prevalent in sub-Saharan Africa, but the role of sexual transmission has not been well characterized. HHV-8 seroprevalence and correlates were evaluated in a cohort of female prostitutes in Mombasa, Kenya. Between February 1993 and January 2000, stored plasma samples taken from 736 women were tested, by whole-virus ELISA assay, for the presence of HHV-8 antibodies; of these 736 women, 633 were included in the analysis of correlates of HHV-8 infection; and, of these 633, 44.1% were seropositive for HHV-8 antibodies. In univariate analysis, age, years of education, years of prostitution, workplace, hormonal contraception, intrauterine-device use, alcohol consumption, syphilis, and gonorrhea were all significantly associated with the presence of HHV-8 antibodies. In a multivariate model, older age, fewer years of education, and 2 markers of high-risk sexual behavior-namely, alcohol consumption and gonorrhea-were each independently associated with HHV-8 seropositivity. These results suggest that heterosexual transmission may contribute to acquisition of HHV-8 infections in this African population of prostitutes.     

Protective and risk factors for toxocariasis in children from two different social classes of Brazil

The aim of this study was to analyze the prevalence of Toxocara spp. antibodies in children from two different socioeconomic classes in the Presidente Prudente municipality, S?o Paulo State, Brazil, and the protective and risk factors associated with toxocariasis. One hundred and twenty-six middle-class (MC) and 126 disadvantaged children (DC) were included in this study. Anti-Toxocara ELISA test was performed in order to evaluate seroprevalence. A survey was applied to the children's guardians/parents in order to analyze the protective and risk factors. The overall prevalence was 11.1%, and of 9.5% (12/126) and 12.7% (16/126) for MC and DC subgroups, respectively. Toxocara seropositivity was inversely proportional to the family income. A high household income was considered a protective factor for toxocariasis in the total population and in both MC and DC subgroups. Being a girl was considered a protective factor for the total population and for both subgroups. Whilst being an owner of cat was a risk factor for children belonging to the total and for both MC and DC subgroups, having dog was considered as a risk factor for only the MC. Epidemiologic protective/factor risks can be distinct depending on the strata of the same population. Thus, it is relevant to evaluate these factors independently for different socioeconomic classes in order to design future investigations and programs for preventing the infection of human beings by Toxocara spp. and other geohelminths.     

Frequency and risk factors for toxocariasis in children from a pediatric outpatient center in southeastern Brazil

To estimate the frequency of anti-Toxocara sp. antibodies, and evaluate factors associated with this infection, sera from 242 male and female children, aged from one to fifteen years old, attended at the Hospital of the Federal University of Uberlandia, Minas Gerais State, Brazil, were analyzed by ELISA. Information on the patients was collected and registered using an investigative questionnaire, and details on possible clinical alterations were obtained from the medical charts of 187 patients. Of a total of 242 samples, 21 (8.7%) were positive for anti-Toxocara sp. antibodies. The presence of dogs and cats and the school variable (place of contact), appeared to be significantly associated (p<0.05) with a positive serology. Respiratory symptoms and eosinophil counts greater than 20% also showed a positive statistical correlation with a positive serology for Toxocara sp.. Factors such as sex and age, and symptoms like headache, stomach ache, convulsive crises and anemia were not associated with toxocariasis.     

Hepatitis C virus seroprevalence and risk factors among patients with HIV infection

The objective of this study was to evaluate the prevalence and risk factors associated with HCV infection in a group of HIV seropositive patients. We analyzed the medical records of 1,457 patients. All patients were tested for HCV infection by third generation ELISA. Whenever possible, a sample of the positive patients was also tested for HCV by PCR. HCV positive patients were analyzed according to their risk factors for both infections. The prevalence of anti-HCV positive patients was 17.7% (258 patients). Eighty-two (82) of these patients were also tested by PCR and 81 were positive for HCV virus (98%). One hundred fifty-one (58.5%) were intravenous drug users (IDU); 42 (16.3%) were sexual partners of HIV patients; 23 (8.9%) were homosexual males; 12 (4.7%) had received blood transfusion; 61 (17.5%) had promiscuous sexual habits; 14 (5.4%) denied any risk factor; 12 (4.7%) were sexual partners of IDU. Two hundred four patients mentioned only one risk factor. Among them, 28 (10.9%) were sexual partners of HIV-positive patients. Although intravenous drug use was the most important risk factor for co-infection, sexual transmission seemed to contribute to the high HCV seroprevalence in this group of patients.     

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.     

Hepatitis C virus infection in Australian psychiatric inpatients: A multicenter study of seroprevalence,risk factors and treatment experience

Screening and treatment for hepatitis C virus (HCV) infection were not prioritised in psychiatric patients due to adverse neuropsychiatric effects of interferon therapy despite reports of high prevalence. However, with the safe new antiviral drugs, HCV eradication has become a reality in these patients. The aim of this study was to report HCV seroprevalence, risk factors and treatment model in an Australian cohort. This prospective study involved patients admitted to four inpatient psychiatric units, from December 2016 to December 2017. After pretest counselling and consent, HCV testing was done; information on risk factors collected. A total of 260 patients (70% male), median age 44 years (IQR 24), were studied. The HCV seroprevalence was 10.8% (28/260) with 95% CI 7‐15. Independent predictors of HCV positivity were injection drug use (P < 0.001, OR 44.05, 95% CI 7.9‐245.5), exposure to custodial stay (P = 0.011, OR 7.34, 95% CI 1.6‐33.9) and age (P = 0.011, OR 1.09, 95% CI 1.02‐1.16). Eight of the 16 HCV RNA‐positive patients were treated. Hepatitis nurses liaised with community mental health teams for treatment initiation and follow‐up under supervision of hepatologists. Seven patients achieved sustained viral response, one achieved end of treatment response. The remaining eight patients were difficult to engage with. In conclusion, HCV prevalence was high in our cohort of psychiatric inpatients. Although treatment uptake was achieved only in 50% patients, it was successfully completed in all, with innovative models of care. These findings highlight the need to integrate HCV screening with treatment linkage in psychiatry practice.