As countries move toward malaria elimination, imported infections become increasingly significant as they often represent the majority of cases, can sustain transmission, cause resurgences, and lead to mortality. Here we review and critique current methods to prevent malaria importation in countries pursuing elimination and explore methods applied in other transmission settings and to other diseases that could be transferred to support malaria elimination. To improve intervention targeting we need a better understanding of the characteristics of populations importing infections and their patterns of migration, improved methods to reliably classify infections as imported or acquired locally, and ensure early and accurate diagnosis. The potential for onward transmission in the most receptive and vulnerable locations can be predicted through high-resolution risk mapping that can help malaria elimination or prevention of reintroduction programs target resources. Cross border and regional initiatives can be highly effective when based on an understanding of human and parasite movement. Ultimately, determining the optimal combinations of approaches to address malaria importation will require an evaluation of their impact, cost effectiveness, and operational feasibility.
Malaria has been the greatest scourge of humankind for many millennia, and as a consequence has had more impact than any other pathogen in shaping the human genome. The sequencing of the human genome provides a new opportunity to determine the genetic traits that confer resistance to infection or disease. The identification of these traits can reveal immune responses, or host–parasite interactions, which may be useful for designing vaccines or new drugs. Similarly, the parasite genome sequence is being exploited to accelerate the development of new antimalarial interventions, for example by identifying parasite metabolic pathways that may be targeted by drugs. The malaria parasites are well known for their ability to undergo antigenic variation, and in parallel to cause a diverse array of disease syndromes, including the severe syndromes that commonly cause death. Genome-based technologies are being harnessed to relate gene and protein expression levels, or genetic variation, to the parasite forms that are targets of protective immunity. Well-conducted clinical studies are required to relate host or parasite diversity with disease. However, genomics studies of human populations raise important ethical issues, such as the disposition of data related to disease susceptibility or paternity, and the ability of communities to understand the nature of the research.
Epidemiology, ventilator management, and outcomes in patients with acute respiratory distress syndrome (ARDS) because of coronavirus disease 2019 (COVID-19) have been described extensively but have never been compared between countries. We performed an individual patient data analysis of four observational studies to compare epidemiology, ventilator management, and outcomes. We used propensity score weighting to control for confounding factors. The analysis included 6,702 patients: 1,500 from Argentina, 844 from Brazil, 975 from the Netherlands, and 3,383 from Spain. There were substantial differences in baseline characteristics between countries. There were small differences in ventilation management. Intensive care unit mortality was higher in Argentina and Brazil compared with the Netherlands and Spain (59.6% and 56.6% versus 32.1% and 34.7%; P <0.001). The median number of days free from ventilation and alive at day 28 was equally low (0 [0–7], 0 [0–18], 1 [0–16], and 0 [0–16] days, respectively; P = 0.03), and the median number of days free from ventilation and alive at day 60 was higher in the Netherlands and Spain (0 [0–37], 0 [0–50], 33 [0–48], and 26 [0–48] days, respectively; P <0.001). Propensity score matching confirmed the outcome differences. Thus, the outcome of COVID-19 ARDS patients in Argentina and Brazil was substantially worse compared with that of patients in the Netherlands and Spain. It is unlikely that this results from differences in case mix or ventilation management.
In recent years, multiple reports have emerged describing real-time quantitative polymerase chain reaction (qPCR) detection of DNA derived from human parasite species in environmental soil samples. In one such report, sampling was focused in impoverished areas of the southeastern United States, and a link between poverty and the presence of parasite DNA in soil was proposed. Whether transmission of certain parasitic diseases persists in the United States in association with poverty remains an important question. However, we emphasize caution when reviewing interpretations drawn solely from qPCR detection of parasite-derived environmental DNA without further verification. We discuss here the limitations of using qPCR to test environmental DNA samples, the need for sampling strategies that are unbiased and repeatable, and the importance of selecting appropriate control areas and statistical tests to draw meaningful conclusions.
Although fresh vegetables are a vital source of essential nutrients and dietary fiber, they can pose a significant health risk due to contamination by intestinal parasites (IPs). The consumption of contaminated vegetables can lead to intestinal parasitic infection, which is a major public health issue, particularly in tropical and subtropical regions, where sanitation, clean water, and agricultural practices are often inadequate. Northeast Thailand, with its warm, humid climate and predominant agricultural sector, exhibits a high prevalence of IPs in humans. This study aimed to determine the prevalence of intestinal parasitic contamination in vegetables in Khon Kaen, Thailand, because of its reported high prevalence of IPs. A total of 300 samples, including cilantro, celery, Thai basil, lettuce, cucumber, Chinese kale, white cabbage, Chinese cabbage, peppermint, and yard-long beans, were collected from 10 markets across five districts in the province. Each sample was washed with 1% normal saline, shaken for 15 minutes, and allowed to sediment. The sediment was then centrifuged and examined by parasitologists under a microscope. The overall prevalence of IPs was found to be 36.0%, with Blastocystis hominis (24.7%), Strongyloides stercoralis (13.0%), and Ascaris lumbricoides (8.7%) being the most common. Peppermint showed the highest prevalence rate at 70.0%, followed by celery and Thai basil at 53.3% each. These results suggest a necessity for key health policy interventions, including appropriate health education. Sanitary measures, such as washing vegetables before consumption and washing hands after harvesting vegetables, should be encouraged among farmers, sellers, and consumers.
In clinical settings, understanding the markers and clinical signs of infection is critical for timely diagnosis and treatment. However, a point-of-care diagnostic test is lacking for noma, a debilitating orofacial infectious disease. This retrospective study reviewed electronic medical records (EMRs) and paper medical records (PMRs) of noma patients from Facing Africa (235 EMRs), Yekatit 12 Hospital (68 PMRs), and Project Harar (33 PMRs) in Ethiopia to identify essential infection markers and clinical presentations of acute noma. The review identified seven acute noma patients aged 4–9 years. The patients presented with facial edema, pain, anorexia, ecchymosis, excessive salivation, and drooling, as well as specific symptoms such as visual disturbances, high fever, foul odor, halitosis, and local tenderness. Laboratory findings included elevated white blood cell counts (13,500–14,500 cells/mcL), C-reactive protein levels (107–148 mg/L), and erythrocyte sedimentation rates (65–90 mm/hour). At >85 ng/mL, procalcitonin levels were particularly high. Accurate diagnosis of noma requires a comprehensive approach that includes thorough clinical examination, appropriate disease stage classification, medical history review, and laboratory testing. The study highlights the critical infection markers and clinical presentations associated with acute noma that may aid in early diagnosis of the disease. Further research with a much larger number of participants is needed. However, given the difficulty in identifying acute noma cases due to the rapid progression and very high mortality of the disease and the challenge of accessing acute noma cases owing to various socioeconomic barriers, the results of this small study are still relevant.
Ralstonia species are recently emerging as pathogens of human importance. This study was performed to assess the distribution of Ralstonia species among bacteremia patients and the clinical and demographical factors of these patients. This retrospective observational study was performed in the Microbiology Department of a tertiary care center in North India from April 2022 to April 2024. All in-patients with blood cultures positive for Ralstonia species for the first time during the study period were included in the study. Positive blood cultures were inoculated on blood and MacConkey agar. Identification was done by matrix-assisted laser desorption ionization–time of flight mass spectrometry, and antibiotic sensitivity testing was determined by disc diffusion assay. During the study period, 26 isolates of Ralstonia species were identified. R. mannitolilytica was the predominant isolate, followed by R. pickettii. Most patients with Ralstonia bacteremia belonged to the age group of <60 years (n = 20; 78%). The median age of the study population was 62 years. The male-to-female ratio was 1.6:1. Most of the patients presented with complaints of fever (77%), followed by epigastric pain (38.4%). Among the underlying comorbidities, most of the patients with Ralstonia bacteremia had sepsis (73%), followed by multiorgan dysfunction syndrome (30.7%). None of the R. mannitolilytica isolates showed sensitivity to imipenem, meropenem, aztreonam, and ceftazidime. On comparing both the isolates, R. pickettii showed better sensitivity to amikacin, imipenem, meropenem, aztreonam, and ceftazidime than R. mannitolilytica. Overall mortality of the patients in the study was 22% (n = 6).
The American Journal of Tropical Medicine and Hygiene is a peer-reviewed journal published monthly by the American Society of Tropical Medicine and Hygiene and consists of two complete, sequentially numbered volumes each calendar year.
Journal Affiliation: The American Journal of Tropical Medicine and Hygiene is the official scientific journal of the American Society of Tropical Medicine and Hygiene (ASTMH). The Society is a nonprofit, professional organization whose mission is to promote world health by the prevention and control of tropical disease through research and education.
Frequency: Monthly
Coverage: 1921 -
Journal Facts
The American Journal of Tropical Medicine and Hygiene, established in 1921, is published monthly by the American Society of Tropical Medicine and Hygiene. It is among the top-ranked tropical medicine journals in the world publishing original scientific articles and the latest science covering new research with an emphasis on population, clinical and laboratory science and the application of technology in the fields of tropical medicine, parasitology, immunology, infectious diseases, epidemiology, basic and molecular biology, virology and international medicine. The Journal publishes unsolicited peer-reviewed manuscripts, review articles, short reports, images in Clinical Tropical Medicine, case studies, reports on the efficacy of new drugs and methods of treatment, prevention and control methodologies,new testing methods and equipment, book reports and Letters to the Editor. Topics range from applied epidemiology in such relevant areas as AIDS to the molecular biology of vaccine development. The Journal is of interest to epidemiologists, parasitologists, virologists, clinicians, entomologists and public health officials who are concerned with health issues of the tropics, developing nations and emerging infectious diseases. Major granting institutions including philanthropic and governmental institutions active in the public health field, and medical and scientific libraries throughout the world purchase the Journal. Two or more supplements to the Journal on topics of special interest are published annually. These supplements represent comprehensive and multidisciplinary discussions of issues of concern to tropical disease specialists and health issues of developing countries.
The American Journal of Tropical Medicine was published by the American Society of Tropical Medicine (ASTM) beginning in 1921. Thirty years later, the ASTM merged with the National Malaria Society (NMS) and the two organizations together became what is now known as the American Society of Tropical Medicine and Hygiene (ASTMH). In 1952 they published Volume 1 of the American Journal of Tropical Medicine and Hygiene (AJTMH). The archived journals of the National Malaria Society can be found here.