Transactions of the Royal Society of Tropical Medicine and Hygiene

Editorial Board

2012-05-01

Fifty years of dengue in India

Anita Chakravarti, Rohit Arora, Christine Luxemburger — 2012-05-01

Summary: Dengue is the most important mosquito-borne, human viral disease in many tropical and sub-tropical areas. In India the disease has been essentially described in the form of case series. We reviewed the epidemiology of dengue in India to improve understanding of its evolution in the last 50 years and support the development of effective local prevention and control measures. Early outbreak reports showed a classic epidemic pattern of transmission with sporadic outbreaks, with low to moderate numbers of cases, usually localized to urban centres and neighbouring regions, but occasionally spreading and causing larger epidemics. Trends in recent decades include: larger and more frequent outbreaks; geographic expansion of endemic transmission; spread of the disease from urban to peri-urban and rural areas; an increasing proportion of severe cases and deaths; and progression to hyperendemicity, particularly in large urban areas. The global picture of dengue in India is currently that of a largely endemic country. Understanding demographic differences in infection rates and severity of dengue has important implications for the planning and implementation of effective public health prevention and control measures and targeting of future vaccination campaigns.

High frequency of asymptomatic Leishmania spp. infection among HIV-infected patients living in endemic areas for visceral leishmaniasis in Brazil

2012-05-01

Abstract: This study aims at estimating the prevalence of Leishmania infection among HIV-infected patients through the use of non-invasive tests. The study was conducted in three Infectious Diseases Services in two large Brazilian cities, both endemic areas for visceral leishmaniasis. Three hundred and eighty-one asymptomatic patients were enrolled whose ages ranged from 19 to 58 years old; 63.5% were men; mean TCD4+ was 380 cells/μl; and mean viral load was 153800 copies/ml. All individuals were tested for Leishmania infection through: ELISA using crude Leishmania infantum (ELISA), ELISA using the recombinant K39 antigen (rK39), indirect fluorescent antibody test (IFAT) and PCR targeted to kDNA region. The tests’ positivity were: 10.8% (ELISA), 3.9% (IFAT), 0.8% (rK39), 6.3% PCR and 20.2% (overall, at least one positive test), with no statistical correlation between positivity and clinical and laboratorial variables. Concordance among tests was low (Kappa <0.20). Prevalence of Leishmania asymptomatic infection was high in this population, reinforcing the need for attention in the evaluation of HIV patients from endemic areas. New efforts are needed to develop more specific and sensitive tests to diagnose Leishmania asymptomatic infection. Highly active antiretroviral therapy (HAART) seems to have a protective role against disease progression in co-infected individuals.

Laboratory quality control in a multicentre meningococcal carriage study in Burkina Faso

2012-05-01

Abstract: To investigate the potential herd immunity effect of MenAfriVac, a new conjugate vaccine against serogroup A Neisseria meningitidis, a multiple cross-sectional carriage study was conducted in three districts in Burkina Faso in 2009, yielding a total of 20 326 oropharyngeal samples. A major challenge was the harmonisation of operational procedures and ensuring the reliability of results. Here we describe the laboratory quality control (QC) system that was implemented. Laboratory analysis performed by three local laboratories included colony morphology assessment, oxidase test, Gram stain, β-galactosidase activity using o-nitrophenyl-β-galactopyranoside (ONPG), γ-glutamyl transferase (GGT) activity and slide agglutination serogrouping. Internal QC was performed on media, reagents, laboratory equipment and field conditions. Confirmation of results and molecular characterisation was performed at the Norwegian Institute of Public Health (Oslo, Norway). External QC was performed on 3% of specimens where no colonies morphologically resembling N. meningitidis had been identified and on 10% of non-ONPG−/GGT+ isolates. The QC system was a critical element: it identified logistical and operational problems in real time and ensured accuracy of the final data. The overall N. meningitidis carriage prevalence (3.98%) was probably slightly underestimated and the calculated true prevalence was 4.48%. The components of the presented QC system can easily be implemented in any other laboratory study.

Hantavirus pulmonary syndrome: prognostic factors for death in reported cases in Brazil

2012-05-01

Abstract: Hantavirus pulmonary syndrome (HPS) was described for the first time in Brazil in 1993 and has occurred endemically throughout the country. This study analysed clinical and laboratory aspects as well as death-related factors for HPS cases in Brazil from 1993 to 2006. The investigation comprised a descriptive and exploratory study of the history of cases as well as an analytical retrospective cohort survey to identify prognostic factors for death due to HPS. A total of 855 Brazilian HPS cases were assessed. The majority of cases occurred during spring (33.5%) and winter (27.6%), mainly among young male adults working in rural areas. The global case fatality rate was 39.3%. The mean interval between the onset of symptoms and hospitalisation was 4 days and that between hospitalisation and death was 1 day. In the multiple regression analysis, adult respiratory distress syndrome and mechanical respiratory support were associated with risk of death; when these two variables were excluded from the model, dyspnoea and haemoconcentration were associated with a higher risk of death.

Risk factors for unfavorable outcome of pulmonary tuberculosis in adults in Taipei, Taiwan

Yung-Feng Yen, Muh-Yong Yen, Hsiu-Chen Shih, Chung-Yeh Deng — 2012-05-01

Summary: This study was undertaken to identify factors associated with unfavorable outcomes in patients with pulmonary tuberculosis (PTB) in Taipei, Taiwan in 2007–2008. Taiwanese adults with culture-positive PTB diagnosed in Taipei during the study period were included in this retrospective cohort study. Unfavorable outcomes were classified as treatment default, death, treatment failure, or transfer. Of 1616 eligible patients, 22.6% (365) had unfavorable outcomes, mainly death. After controlling for patient sociodemographic factors, clinical findings, and underlying disease, independent risk factors for unfavorable outcomes included advanced age, unemployment, end-stage renal disease requiring dialysis, malignancy, acid-fast bacilius smear–positivity, multidrug-resistant TB, and notification from ordinary ward or intensive care unit. In contrast, patients receiving directly observed treatment, and with a high school or higher education were significantly less likely to have unfavorable outcomes. This study advanced our understanding by revealing that a high school or higher education might lower the risk of an unfavorable outcome. Our results also confirmed the risk factors for unfavorable outcomes shown in previous research. Future TB control programmes in Taiwan should target particularly high-risk patients including those who had lower educational levels.

Characterization of Neisseria meningitidis isolates from Egypt using multilocus sequence typing

2012-05-01

Summary: To characterize Neisseria meningitidis isolates collected from cerebrospinal fluid of meningitis cases in Egypt (1998–2003) as part of surveillance studies, 67 isolates were serogrouped, tested for antibiotic sensitivity and analyzed using multilocus sequence typing (MLST).Results show that isolates expressing serogroup B (50.7%) and serogroup A (34.3%) antigens were predominant in Egypt during the surveillance period, possibly due to suppression of other serogroups by meningococcal vaccines in current use. Intermediate resistance to penicillin was observed in 71% of the isolates, suggesting a need for physicians to shift to third-generation cephalosporins during the empirical treatment of infection. Recurrent lineages of N. meningitidis in Egypt appear to originate from Europe and other Middle Eastern countries. Of 19 sequence types detected, five were unique to Africa and 10 were not observed previously in the MLST database. The information obtained illustrates the changing dynamics of meningitis after vaccine introduction in Egypt.

A community empowerment strategy embedded in a routine dengue vector control programme: a cluster randomised controlled trial

2012-05-01

Abstract: The non-sustainability of vertically organised dengue vector control programmes led to pleas for changing the emphasis towards community-based strategies. We conducted a cluster randomised controlled trial with 16 intervention and 16 control clusters to test the effectiveness of a community empowerment strategy intertwined with the routine dengue vector control programme in La Lisa, Havana City, Cuba. The intervention included four components on top of routine control: organisation and management; entomological risk surveillance; capacity building; and community work for vector control. In the control clusters, routine activities continued without interference. The community participation score increased from 1.4 to 3.4. Good knowledge of breeding sites increased by 52.8% and 27.5% in the intervention and control clusters, respectively. There were no changes in adequate Aedes aegypti control practices at household level in the control clusters, but in the intervention clusters adequacy increased by 36.2%. At baseline, the Breteau indices (BI) were approximately 0.1 and were comparable; they fluctuated over time but became different with the launch of the community-based dengue control activities in the intervention clusters. Over the intervention period, the BI remained 53% (95% CI 22–92%) lower in these clusters than in the control clusters. The empowerment strategy increased community involvement and added effectiveness to routine A. aegypti control.

An age-adjusted seroprevalence study of Toxoplasma antibody in a Malaysian ophthalmology unit

2012-05-01

Summary: Toxoplasma gondii is a public health risk in developing countries, especially those located in the tropics. Widespread infection may inflict a substantial burden on state resources, as patients can develop severe neurological defects and ocular diseases that result in lifelong loss of economic independence. We tested sera for IgG antibody from 493 eye patients in Malaysia. Overall age-adjusted seroprevalence was estimated to be 25% (95% CI: [21%, 29%]). We found approximately equal age-adjusted seroprevalence in Chinese (31%; 95% CI: [25%, 38%]) and Malays (29%; 95% CI: [21%, 36%]), followed by Indians (19%; 95% CI: [13%, 25%]). A logistic regression of the odds for T. gondii seroprevalence against age, gender, ethnicity and the occurrence of six types of ocular diseases showed that only age and ethnicity were significant predictors. The odds for T. gondii seroprevalence were 2.7 (95% CI for OR: [1.9, 4.0]) times higher for a patient twice as old as the other, with ethnicity held constant. In Malays, we estimated the odds for T. gondii seroprevalence to be 2.9 (95% CI for OR: [1.8, 4.5]) times higher compared to non-Malays, with age held constant. Previous studies of T. gondii seroprevalence in Malaysia did not explicitly adjust for age, rendering comparisons difficult. Our study highlights the need to adopt a more rigorous epidemiological approach in monitoring T. gondii seroprevalence in Malaysia.

Comment on: Preventive chemotherapy in human helminthiasis: theoretical and operational aspects

G.C. Coles — 2012-05-01

The justification for strategies to control major human helminth infections has been clearly set out by Gabrielli et al. There is an obvious need to try to reduce infection and morbidity with the ultimate aim of eradication of infections.

Comment on: Predictors of immune recovery and the association with late mortality while on antiretroviral treatment in Cambodia

S.M. Hermans, J. Sempa, B. Castelnuovo, Y.C. Manabe, F. van Leth — 2012-05-01

We read with great interest the article by van Griensven and Thai, who report on the risk factors for late mortality after antiretroviral therapy (ART) initiation in a cohort of 2840 patients in Cambodia. The main risk factor identified was time-updated CD4 cell count, which is consistent with the findings of other studies in different settings. They also analysed predictors of immune recovery, including the use of different non-nucleoside reverse transcriptase inhibitors (NNRTI). Their analysis showed a negative effect of the use of nevirapine (NVP) versus efavirenz (EFV) on CD4 recovery over time. This finding is very interesting as it is contradictory to other reports, including a randomised open-label trial and a meta-analysis.

Comment on: The seroprevalence of Helicobacter pylori and its relationship to malaria in Ugandan children

Elin Hestvik, Thorkild Tylleskar — 2012-05-01

Gupta et al. present seroprevalence of Helicobacter pylori in 200 children living in Kampala, Uganda, more specifically in the area of Mulago III, without attention to our previously published work in children living in the adjacent neighbourhood of Mulago II, where we studied the prevalence of H. pylori antigen in 427 apparently healthy children using a non-invasive faecal monoclonal antibody test. Gupta et al. are confirming our three main findings: increasing prevalence with age; boys are more frequently colonized with H. pylori compared with girls; and that children living in households with the lowest wealth index are more often colonized. However, we found a remarkably lower prevalence of 44.3% in children aged 0–12 years old. We have also studied 219 HIV-infected, HAART-naive children admitted to the Mulago National Referral Hospital which is within walking distance of the Mulago III neighbourhood. These children had an overall H. pylori prevalence of only 22.5%.

Reply to comment on: The seroprevalence of Helicobacter pylori and its relationship to malaria in Ugandan children

2012-05-01

We regret that the work of Hestvik and colleagues was not cited in our paper; we were, unfortunately, unaware of these previous studies in Uganda. The studies from both groups, which used different tests to identify Helicobacter pylori infection, demonstrated similar associations between the prevalence of H. pylori and age, gender and household socioeconomic factors. As noted by Hestvik and Tylleskar, our study found a considerably higher prevalence of H. pylori, which is probably due to the fact that we studied seropositivity rather than faecal antibody positivity. Hestvik and colleagues suggest that H. pylori infection in many children in Kampala can clear if antibiotic use coincides with deworming treatment leading to a higher prevalence as measured by serological tests that might identify recent and current infection. In comparison, the faecal monoclonal antibody test might identify only current infections that have not been suppressed by recent antibiotic use which appears to be common in their study population.