Tropical Medicine and Infectious Disease最新文献

Resistance to current antimalarial drugs is steadily increasing, and new drugs are required. Drug efficacy trials remain the gold standard to assess the effectiveness of a given drug. The World Health Organization (WHO)'s recommendation for the optimal duration of follow-up for assessing antimalarial efficacy is a minimum of 28 days. However, assessing antimalarial drug efficacy in highly endemic regions can be challenging due to the potential risks of acquiring a new infection in the follow-up period, and thus, it may underestimate the efficacy of the given drugs. A new treatment should be introduced if treatment failure rates exceed 10%. Overestimation occurs as a result of retaining a drug with a clinical efficacy of less than 90% with increases in morbidity and mortality, while underestimation may occur due to a misclassification of new infections as treatment failures with tremendous clinical and economic implications. Therefore, molecular genotyping is necessary to distinguish true new infections from treatment failures to ensure accuracy in determining antimalarial efficacy. There are three genetic markers that are commonly used in antimalarial efficiency trials to discriminate between treatment failures and new infections. These include merozoite surface protein 1 (msp-1), merozoite surface protein 2 (msp-2), and glutamate-rich protein (glurp). The genotyping of P. falciparum by nested polymerase chain reaction (n-PCR) targeting these markers is discussed with the inherent limitations and uncertainties associated with the PCR technique and limitations enforced by the parasite's biology itself.

Background/objectives: Leptospirosis is a zoonotic disease that is widely distributed around the world and presents symptoms similar to other febrile illnesses in tropical regions, which complicates clinical diagnosis. This study aimed to evaluate the performance and agreement between serological diagnostic tests for detecting both acute and convalescent human leptospirosis, using the micro agglutination test (MAT) as a reference in an endemic region of the Colombian Caribbean.

Methods: A prospective descriptive study was conducted on 275 participants with suspected leptospirosis. Paired serum samples were obtained, and an epidemiological survey was conducted. Using the MAT as the gold standard, we calculated positive and negative predictive values, sensitivity, specificity, and kappa index. A Bayesian latent class model was also used to compare the diagnostic tests.

Results: In 223 paired serum samples, the sensitivity values for various stages of the disease ranged between 10.8% to 54.1% in the acute and 6.1% to 66.7% during the convalescent phase compared to the MAT. According to the Bayesian model, sensitivity was 9.5% to 75.3% in the acute phase and 5.7% to 85.3% in the convalescent phase. The Kappa value, an indicator of agreement, was moderate for the IgM ELISA in the acute phase (0.553) and substantial in the convalescent phase (0.692).

Conclusions: The MAT was the best confirmatory test in both acute and convalescent phases of leptospirosis. Despite the high specificity of ELISA, 21.62% of participants identified as negative by IgM-ELISA in both phases were subsequently confirmed as positive by the MAT. It is necessary to re-evaluate diagnostic guidelines that do not employ the MAT for confirmation and to enhance the diagnostic and clinical identification of leptospirosis within healthcare institutions and public health laboratories while providing a rapid and reliable test for its implementation.

Leptospirosis and hantavirus syndrome are two major rodent-borne diseases in Taiwan. Rocahepevirus ratii (RHEV), a virus closely related to hepatitis E virus (HEV, Paslahepevirus balayani), is emerging and has been reported to cause hepatitis in humans. We employed wastewater-based epidemiology to actively monitor rodent-borne pathogens, and the correlations with human cases were evaluated. Wastewater was collected using grab sampling at 11 sites along a sewer system including influents and effluents at a wastewater treatment plant in Tamsui, New Taipei City, Taiwan, monthly during June 2023 to May 2024. The presence of pathogens was examined by reverse transcription-polymerase chain reaction (RT-PCR). The result showed an overall positivity rate of 38.2% (50/131). Leptospira was detected most often (48/131, 36.6%), and RHEV and hantaviruses were found once each during the study period. Sequencing identified Leptospira interrogans close to isolates from rodents and human cases, while sequences of hantavirus and RHEV were most similar to isolates from rodents. No significant correlation was found with human cases or positive samples for rodent DNA. Here, we present an example of a One Health approach applying wastewater to environmental surveillance for the early detection and prevention of emerging diseases.

Malaria prevention and control programs are mainly oriented to vector control, timely diagnosis and adequate treatment. Malaria transmission is influenced by several factors, including biological and social aspects. Thus, it is relevant to consider community beliefs and practices to ensure sustainable prevention and control strategies. This study aimed to determine knowledge, attitudes and practices (KAP) towards malaria in an endemic locality in northwestern Colombia. Preliminary data were collected through a focus group discussion. Subsequently, a KAP survey was administered to the community. KAP scores were associated with both sociodemographic characteristics and with previous malaria infection. Focus group data revealed knowledge gaps and the absence of or having worn-out nets. Survey results showed that participants recognized a mosquito bite as the transmission mode (72.09%), followed by dirty water (44.19%), high fever (86.05%) and headache (79.07%) as the main symptoms. Regarding attitudes, 44.19% of the people would go to the hospital in the case of having symptoms. The most recognized practices for disease prevention were the use of mosquito nets (65.12%) and fans (23.26%). The results showed that some people had misconceptions about the disease transmission mode. The analysis showed significant associations of either female gender and homemaker occupation with a good knowledge [OR = 3.74, (p = 0.04), OR = 3.55, (p = 0.04), respectively] or female with a positive attitude towards malaria control and prevention [OR = 4.80, (p = 0.04)]. These results showed that the identified gaps in KAP require increasing education among the community in addition to applying public health prevention efforts. The data may be useful in designing malaria control strategies that involve community participation.

Two-thirds of children with cerebral malaria (CM) exhibit retinopathy characterized by whitening, vessel color changes, and/or hemorrhages. The pathogenesis of malarial retinopathy is not fully understood. This study aimed to assess the relationship between malarial retinopathy and the severity of its components (macular whitening, retinal hemorrhages, and vessel color changes) with the total, circulating, or sequestered parasite load in children with CM. Total parasite burden was estimated by measuring plasma levels of Plasmodium falciparum histidine-rich protein 2 (PfHRP2), while the sequestered load was calculated as the difference between the total burden and circulating parasitemia. Children with retinopathy-positive CM (n = 172) had higher total and sequestered parasite burdens compared to retinopathy-negative children (n = 42) (both p = 0.049). In a subgroup with detailed retinopathy grading (n = 52), more extensive vessel color changes correlated with higher total, sequestered, and circulating parasite loads (p = 0.0057, p = 0.0068, and p = 0.0433, respectively). Peripheral retinal whitening was also associated with increased total and sequestered loads (p = 0.0017 and p = 0.0012). No association was found between retinal hemorrhages and parasite burden, indicating that other factors may influence their pathogenesis.

The diagnosis of canine visceral leishmaniasis (CVL) presents a challenge due to a variety of non-specific clinical signs. The available tests have low sensitivity. This study aimed to standardize and evaluate the loop-mediated isothermal amplification technique with K26 target (K26-LAMP) for diagnosis of CVL in conjunctival swab (CS) DNA samples extracted through a silica column commercial kit (SW-kit) and boiling (SW-DB) and to compare sensitivity with conventional PCR (kDNA-cPCR) and quantitative real-time PCR (18S-qPCR). Clinical samples of CSs were collected from 54 dogs after reactive serology tests. Positive parasitological and/or histological tests were used as inclusion criteria for a sensitivity analysis. A total of 79.2% (43/54) of dogs without clinical signs or with mild, moderate, or severe clinical signs were included in the study. The sensitivity results of K26-LAMP, kDNA-cPCR, and 18S-qPCR were 72.1%, 81.4%, and 80.5% with the SW-kit and 97.2%, 95.2%, and 57.1% with SW-DB, respectively. In all techniques, the proportion of positives was higher in the group with severe clinical disease, with statistically significant differences in the K26-LAMP and 18S-qPCR techniques being seen with the SW-kit. The results obtained with LAMP for CS samples are promising and its performance is similar to other techniques.

The World Health Organization is encouraging countries to include contact screening and single-dose rifampicin administration as preventive chemotherapy for contacts of leprosy patients in their leprosy control activities. However, no study has been conducted to assess the safety of SDR-PEP and the acceptability and feasibility of this intervention in Togo. To assess the safety of SDR-PEP, we used a cohort design, and for acceptability and feasibility, we used a mixed method, combining a quantitative study to assess the safety of SDR-PEP in a cohort of contacts from recently diagnosed leprosy patients followed by a qualitative study to identify the social, cultural, or institutional factors that would influence the adoption of single-dose rifampicin as post-exposure prophylaxis for contacts of leprosy patients in Togo. For the quantitative study, all identified index patients agreed to the disclosure of their status to their contacts and provided a list of their contacts. All the contacts found agreed to take part in the study, and an appointment was made for screening. However, some contacts were absent on the screening day for no reason. All eligible contacts agreed to take SDR and were followed up after taking the drug. No severe adverse events were reported during the follow-up. For the qualitative study, 72 interviews (66 semi-structured interviews and 6 focus groups) were carried out, and it emerged that, overall, opinions were favorable on the acceptability and feasibility of implementing single-dose rifampicin as post-exposure prophylaxis for contacts of leprosy patients in Togo. However, a number of conditions need to be considered for more effective results.

The global HIV landscape has changed over the past few decades, with great milestones achieved in both HIV treatment and prevention [...].

Schistosomiasis, a parasitic disease with a complex transmission mechanism, requiring a snail intermediate host, is influenced by biology, the environment, human behavior and the prevailing socioeconomic situation. This study aimed to systematically investigate the importance and feasibility of indicators related to the factors influencing transmission and intervention measures for Schistosoma mansoni and S. haematobium. Based on a literature review and group discussions according to the Delphi method, a framework questionnaire was designed. A total of 33 experts on schistosomiasis were invited, and 27 were accepted, to rate the importance and feasibility of indicators for transmission with and the control of schistosomiasis, with a focus on intervention measures for S. mansoni and S. haematobium infections in Zimbabwe. After two rounds of Delphi consultations with these experts, calculated to have a high average authority coefficient (0.88), a consensus was reached on a framework that included 2 primary, 6 secondary and 39 tertiary indicators. The Delphi-entropy method was applied to assess the weight of each indicator. The key influencing factors included hazardous water exposure, accessibility to safe drinking water, sanitary facilities and the contamination of water bodies by outdoor defecation/urinary habits. The intervention measures involved improved diagnostics, health education, preventive chemotherapy, the presence of national control plans and the implementation of the strategy on water, sanitation and hygiene (WASH). While these factors are already well known, their detailed order of importance could help to improve the allocation of specific control efforts.