Stella van Beers

Impact of land-use change on dengue and malaria in northern Thailand

Land-use change, a major constituent of global environmental change, potentially has significant consequences for human health in relation to mosquito-borne diseases. Land-use change can influence mosquito habitat, and therefore the distribution and abundance of vectors, and land use mediates human–mosquito interactions, including biting rate. Based on a conceptual model linking the landscape, people, and mosquitoes, this interdisciplinary study focused on the impacts of changes in land use on dengue and malaria vectors and dengue transmission in northern Thailand. Extensive data on mosquito presence and abundance, land-use change, and infection risk determinants were collected over 3 years. The results of the different components of the study were then integrated through a set of equations linking land use to disease via mosquito abundance. The impacts of a number of plausible scenarios for future land-use changes in the region, and of concomitant behavioral change were assessed. Results indicated that land-use changes have a detectable impact on mosquito populations and on infection. This impact varies according to the local environment but can be counteracted by adoption of preventive measures.

Review: Mycobacterium leprae - millennium resistant! Leprosy control on the threshold of a new era

Summary Over the past decades, the conditions of leprosy control implementation have changed dramatically. Introduction of multidrug therapy, together with the global effort of the World Health Organization to eliminate leprosy as a public health problem, had a tremendous impact on leprosy control, particularly by decreasing the registered prevalence of the disease. At the beginning of the new millennium, leprosy control programmes face several new challenges. These relate not only to changes in the prevalence of the disease, but also to changes in the context of leprosy control, such as those created by health sector reforms and other disease control programmes. This review discusses current knowledge on the epidemiology of Mycobacterium leprae and some important aspects of leprosy control. It is argued that our understanding is still insufficient and that, so far, no consistent evidence exists that the transmission of leprosy has been substantially reduced. Sustainable leprosy control, rather than elimination, should be our goal for the foreseeable future, which also includes care for patients on treatment and for those released from treatment. This, however, requires new strategies.

An approach to understanding the transmission of Mycobacterium leprae using molecular and immunological methods: results from the MILEP2 study.

BACKGROUND The current strategy for leprosy control using case detection and treatment has greatly reduced the prevalence of leprosy, but has had no demonstrable effect on interrupting transmission. METHODS Three leprosy endemic communities in India were recruited, examined, and followed up sequentially over 2 yrs using nasal swabs and saliva collections. The nasal swabs were tested by polymerase chain reaction for the presence of M. leprae and the saliva was assayed for anti-M. leprae IgA. FINDINGS Only 1.6% of 2552 nasal swabs were PCR positive, and 68% of saliva samples were positive for ML-IgA. BCG and household contact status was associated with the mucosal immune response, but not with PCR positivity. PCR positivity did not persist and most PCR positive results were in the wet season. INTERPRETATION The findings contribute to our understanding of the epidemiology of M. leprae and the possible periods of greatest likelihood of exposure and transmission.

The relation between seroprevalence of antibodies against phenolic glycolipid-I among school children and leprosy endemicity in Brazil

Leprosy control programs would benefit expressively from an easy method to estimate disease prevalence and to assess the effect of leprosy control measures on disease prevalence. Determination of the seroprevalence of antibodies to PGL-I through school children surveys might be a useful indicator of leprosy prevalence at the district level. To investigate whether seropositivity rates could be related to leprosy detection rates and whether seropositivity could be used as a proximal indicator to predict the leprosy incidence in other areas, 7,073 school children in three different leprosy-endemic states in Brazil were tested. The results show a widely varying distribution of seropositivity in the communities independent of the number of leprosy cases detected. Seroprevalence was significantly lower at private schools. No differences in the patterns of seropositivity between ELISA and dipstick were observed. No correlation between leprosy detection rate and seropositivity rates could be established.

Critical review of the Stepwise Laboratory Improvement Process Towards Accreditation (SLIPTA): suggestions for harmonization, implementation and improvement.

Objective  Clinical laboratories in low‐ and middle‐income countries (LMIC) need fundamental improvement because quality laboratory services are essential for the decision‐making capacity of clinicians, health workers and public health authorities. To this end, a tiered accreditation scheme Stepwise Laboratory Improvement Process Towards Accreditation (SLIPTA) was developed by WHO‐AFRO, CDC and others for clinical laboratories in LMIC. One to five stars are accredited to laboratories based on the level of compliance with a checklist. Our aim was to evaluate the quality and applicability of this accreditation scheme compared with international quality standards.

Global laboratory initiative tool for a stepwise process towards tuberculosis laboratory accreditation.

made with this new test in detecting tuberculosis among patients excreting few bacilli and in identifying rifampicin resistance. For the reasons outlined above and in our article, sputum smear microscopy must be retained as a routine test at peripheral level in low-income countries, at least for the time being. We wish to emphasise the need for good operational research before recommending any replacement of smear microscopy. The old cloth must not be discarded without due assurance that the new cloth is affordable, durable and resistant to stormy weather!

Risk Factors of Typhoid Infection in the Indonesian Archipelago

Background Knowledge of risk factors and their relative importance in different settings is essential to develop effective health education material for the prevention of typhoid. In this study, we examine the effect of household level and individual behavioural risk factors on the risk of typhoid in three Indonesian islands (Sulawesi, Kalimantan and Papua) in the Eastern Indonesian archipelago encompassing rural, peri-urban and urban areas. Methods We enrolled 933 patients above 10 years of age in a health facility-based case-control study between June 2010 and June 2011. Individuals suspected of typhoid were tested using the typhoid IgM lateral flow assay for the serodiagnosis of typhoid fever followed by blood culture testing. Cases and controls were defined post-recruitment: cases were individuals with a culture or serology positive result (n = 449); controls were individuals negative to both serology and culture, with or without a diagnosis other than typhoid (n = 484). Logistic regression was used to examine the effect of household level and individual level behavioural risk factors and we calculated the population attributable fraction (PAF) of removing each risk significant independent behavioural risk factor. Results Washing hands at critical moments of the day and washing hands with soap were strong independent protective factors for typhoid (OR = 0.38 95% CI 0.25 to 0.58 for each unit increase in hand washing frequency score with values between 0 = Never and 3 = Always; OR = 3.16 95% CI = 2.09 to 4.79 comparing washing hands with soap sometimes/never vs. often). These effects were independent of levels of access to water and sanitation. Up to two thirds of cases could be prevented by compliance to these practices (hand washing PAF = 66.8 95% CI 61.4 to 71.5; use of soap PAF = 61.9 95%CI 56.7 to 66.5). Eating food out in food stalls or restaurant was an important risk factor (OR = 6.9 95%CI 4.41 to 10.8 for every unit increase in frequency score). Conclusions Major gains could potentially be achieved in reducing the incidence of typhoid by ensuring adherence to adequate hand-washing practices alone. This confirms that there is a pivotal role for ‘software’ related interventions to encourage behavior change and create demand for goods and services, alongside development of water and sanitation infrastructure.