Large-scale malaria survey in Cambodia: Novel insights on species distribution and risk factors

BACKGROUND: In Cambodia, estimates of the malaria burden rely on a public health information system that does not record cases occurring among remote populations, neither malaria cases treated in the private sector nor asymptomatic carriers. A global estimate of the current malaria situation and associated risk factors is, therefore, still lacking. METHODS: A large cross-sectional survey was carried out in three areas of multidrug resistant malaria in Cambodia, enrolling 11,652 individuals. Fever and splenomegaly were recorded. Malaria prevalence, parasite densities and spatial distribution of infection were determined to identify parasitological profiles and the associated risk factors useful for improving malaria control programmes in the country. RESULTS: Malaria prevalence was 3.0%, 7.0% and 12.3% in Sampovloun, Koh Kong and Preah Vihear areas. Prevalences and Plasmodium species were heterogeneously distributed, with higher Plasmodium vivax rates in areas of low transmission. Malaria-attributable fevers accounted only for 10–33% of malaria cases, and 23–33% of parasite carriers were febrile. Multivariate multilevel regression analysis identified adults and males, mostly involved in forest activities, as high risk groups in Sampovloun, with additional risks for children in forest-fringe villages in the other areas along with an increased risk with distance from health facilities. CONCLUSION: These observations point to a more complex malaria situation than suspected from official reports. A large asymptomatic reservoir was observed. The rates of P. vivax infections were higher than recorded in several areas. In remote areas, malaria prevalence was high. This indicates that additional health facilities should be implemented in areas at higher risk, such as remote rural and forested parts of the country, which are not adequately served by health services. Precise malaria risk mapping all over the country is needed to assess the extensive geographical heterogeneity of malaria endemicity and risk populations, so that current malaria control measures can be reinforced accordingly

Adaptive Management: A Methodology for Ecosystem and Community-based Rodent Management in Cambodia

There appears to be no easy solution to reducing crop damage caused by rodents in Cambodia and other parts of Southeast Asia. Agricultural and pest management scientists focusing on technological improvements have expressed frustration with the apparent slow uptake of management options produced from an 80-year history of research. In Cambodia, rats destroy an estimated average 0.1% of the total rice production area annually. This may sound barely perceptible, but damage is often very patchy and locally severe. An outbreak in 1996 was reported to have destroyed rice sufficient to feed over 50,000 people for one year. Typically, farmers’ rat management efforts have had poor success. There is an increasing awareness that traditional research, development and extension (RD&E) approaches have frequently led to inappropriate, irrelevant and unequally distributed technologies and unrepresentative decision-making. This paper provides an overview of one approach, adaptive management (AM), which aims to overcome these problems. An example of the application of AM to improve Cambodian RD&E in rodent management is also presented. We propose that the management of rodent problems in lowland rice could improve dramatically if approaches are community-based and if the concept of uncertainty is incorporated as an integral part of the decisionmaking process

Clinical features of Mycobacterium canettii infection: a retrospective study of 20 cases among French soldiers and relatives

International audienceBackground: Mycobacterium canettii forms part of the Mycobacterium tuberculosis complex. M. canettii infections are mainly described in the Horn of Africa. The permanent presence of French soldiers in Djibouti raises the question of the risk of being infected with M. canettii. Our study aims to describe M. canettii infections among French military or their families between 1998 and 2015. Methods: This retrospective study relied on 3 sources of data: the reference centre for mycobacteria in the Biology Department at Percy military hospital in Paris, the French Military Center for Epidemiology and Public Health, and the scientific literature. After an exhaustive census of the strains, we studied the epidemiological data on 20 cases among French soldiers and their families. Results: 20 cases of M. canettii infections are reported, including 5 unpublished cases. Adenitis predominates (n = 15), especially in the cervico facial area and among children; one case was observed one month after dental care in Djibouti. The pulmonary forms were less frequent (n = 6) and 3 atypical forms are described. All patients had stayed in Djibouti. Conclusions: Cases of M. canettii infection among the French military consisted mainly of adenitis; disseminated forms were possible with immunodeficiency. Their evolution under specific treatments were comparable to tuberculosis. The presumed origin of the infection seemed to be environmental, possibly a water reservoir, and not due to human-to-human contagion

Progenitor “Mycobacterium canettii” Clone Responsible for Lymph Node Tuberculosis Epidemic, Djibouti

“Mycobacterium canettii,” an opportunistic human pathogen living in an unknown environmental reservoir, is the progenitor species from which Mycobacterium tuberculosis emerged. Since its discovery in 1969, most of the ≈70 known M. canettii strains were isolated in the Republic of Djibouti, frequently from expatriate children and adults. We show here, by whole-genome sequencing, that most strains collected from February 2010 through March 2013, and associated with 2 outbreaks of lymph node tuberculosis in children, belong to a unique epidemic clone within M. canettii. Evolution of this clone, which has been recovered regularly since 1983, may mimic the birth of M. tuberculosis. Thus, recognizing this organism and identifying its reservoir are clinically important

Significance of the Identification in the Horn of Africa of an Exceptionally Deep Branching <em>Mycobacterium tuberculosis</em> Clade

<div><p>Molecular and phylogeographic studies have led to the definition within the <em>Mycobacterium tuberculosis</em> complex (MTBC) of a number of geotypes and ecotypes showing a preferential geographic location or host preference. The MTBC is thought to have emerged in Africa, most likely the Horn of Africa, and to have spread worldwide with human migrations. Under this assumption, there is a possibility that unknown deep branching lineages are present in this region. We genotyped by spoligotyping and multiple locus variable number of tandem repeats (VNTR) analysis (MLVA) 435 MTBC isolates recovered from patients. Four hundred and eleven isolates were collected in the Republic of Djibouti over a 12 year period, with the other 24 isolates originating from neighbouring countries. All major <em>M. tuberculosis</em> lineages were identified, with only two <em>M. africanum</em> and one <em>M. bovis</em> isolates. Upon comparison with typing data of worldwide origin we observed that several isolates showed clustering characteristics compatible with new deep branching. Whole genome sequencing (WGS) of seven isolates and comparison with available WGS data from 38 genomes distributed in the different lineages confirms the identification of ancestral nodes for several clades and most importantly of one new lineage, here referred to as lineage 7. Investigation of specific deletions confirms the novelty of this lineage, and analysis of its precise phylogenetic position indicates that the other three superlineages constituting the MTBC emerged independently but within a relatively short timeframe from the Horn of Africa. The availability of such strains compared to the predominant lineages and sharing very ancient ancestry will open new avenues for identifying some of the genetic factors responsible for the success of the modern lineages. Additional deep branching lineages may be readily and efficiently identified by large-scale MLVA screening of isolates from sub-Saharan African countries followed by WGS analysis of a few selected isolates.</p> </div

Minimum spanning tree representation of the clustering of 435 isolates from the Horn of Africa.

<p>The color code reflects the main MLVA clusters. Lineages (1 to 6) and some sublineages (CDC1551, H37Rv, …) are indicated. The size of the circles reflects the number of isolates with an identical genotype. Branches longer than 10 are not drawn. The main outlier candidates are arrowed (red arrows: isolates selected for sequencing).</p