Tropical Medicine and Infectious Disease

11 pages, 554 KiB

Open AccessArticle

High Frequency of Deletions in the pfhrp2 and pfhrp3 Genes of Plasmodium falciparum in the Middle Rio Negro Region of the Brazilian Amazon

by Daniela Romero Bally, Simone da Silva Santos, Diego Calafate Arregue, Mariana Kelly de Mattos and Martha C. Suárez-Mutis

Trop. Med. Infect. Dis. 2024, 9(7), 149; https://doi.org/10.3390/tropicalmed9070149 - 2 Jul 2024

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Abstract

Several countries are reporting natural populations of P. falciparum with deletions in the pfhrp2/3 genes that can lead to false-negative results in rapid diagnostic tests. To investigate the prevalence of deletion in the pfhrp2/3 genes in the Rio Negro basin in [...] Read more.

Several countries are reporting natural populations of P. falciparum with deletions in the pfhrp2/3 genes that can lead to false-negative results in rapid diagnostic tests. To investigate the prevalence of deletion in the pfhrp2/3 genes in the Rio Negro basin in the Brazilian Amazon and identify whether there is clinical differentiation between individuals infected by these parasites, clinical samples collected from 2003 to 2016 were analyzed from symptomatic and asymptomatic P. falciparum-infected individuals. The molecular deletion of pfhrp2 and pfhrp3 genes was evaluated using the protocols recommended by the WHO. From 82 samples used, 28 (34.2%) had a single deletion in pfhrp2, 19 (23.2%) had a single deletion in pfhrp3, 15 (18.3%) had a double deletion (pfhrp2/3), and 20 (24.4%) did not have a deletion in either gene. In total, 29.3% of individuals had an asymptomatic plasmodial infection and were 3.64 times more likely to have parasites with a double deletion (pfhrp2/3) than patients with clinical malaria (p = 0.02). The high prevalence of parasites with pfhrp2/3 deletions shows the need to implement a surveillance program in this area. Deletions in parasites may be associated with the clinical pattern of the disease in this area. More studies must be carried out to elucidate these findings. Full article

(This article belongs to the Special Issue Advances in Molecular Diagnosis of Malaria)

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9 pages, 233 KiB

Open AccessReview

Antibiotic Chemoprophylaxis for Leptospirosis: Previous Shortcomings and Future Needs

by Kyle Petersen and Ashley Maranich

Trop. Med. Infect. Dis. 2024, 9(7), 148; https://doi.org/10.3390/tropicalmed9070148 - 2 Jul 2024

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Abstract

Leptospirosis is a neglected tropical disease that remains potentially life threatening and hard to diagnose. Climate change combined with overlap** reservoir and human habitats will likely lead to increasing incidence, outbreaks, and mortality in the future. Preventative vaccines are either of limited scope [...] Read more.

Leptospirosis is a neglected tropical disease that remains potentially life threatening and hard to diagnose. Climate change combined with overlap** reservoir and human habitats will likely lead to increasing incidence, outbreaks, and mortality in the future. Preventative vaccines are either of limited scope and availability, or under development. Antibiotic chemoprophylaxis for prevention has been the subject of numerous clinical trials. However, despite 40 years of effort, clinical trials to better define protective efficacy, dosing, and the preferred medication are of poor quality and offer limited evidence. We reviewed the literature and offer critiques of the existing trials as well as potential areas for future exploration that may better define the epidemiology and yield a better evidence base for both travel medicine and public health efforts. Full article

14 pages, 5219 KiB

Open AccessArticle

Incidence of Scrub Typhus According to Geographical and De-mographical Characteristic Changes in Chungcheong Region

by Sungchan Yang, Gemma Park and Yuna Kim

Trop. Med. Infect. Dis. 2024, 9(7), 147; https://doi.org/10.3390/tropicalmed9070147 - 30 Jun 2024

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Abstract

To determine the incidence trends of scrub typhus in the Chungcheong region, we analyzed the epidemiological survey information of 14,379 cases with scrub typhus reported to the integrated disease health management system of the Korea Centers for Disease Control and Prevention between 2012 [...] Read more.

To determine the incidence trends of scrub typhus in the Chungcheong region, we analyzed the epidemiological survey information of 14,379 cases with scrub typhus reported to the integrated disease health management system of the Korea Centers for Disease Control and Prevention between 2012 and 2022 along with the demographic data collected from the Korean Statistics Information Service. Geographical analyses were performed to confirm the correlation between high-risk areas and the proportion of elderly people. The average age, proportion of elderly people, and changes in the agricultural population were statistically associated with incidence. Incidence of scrub typhus and agricultural population in the Chungcheong region has shown a decrease compared with that in 2012–2013. However, recent trends indicate a resurgence linked to increased outdoor activities with higher risks observed among older age groups. Additionally, advancing age correlates with a heightened probability of reinfection and additional infections with other febrile diseases. The incidence of scrub typhus in the Chungcheong region (2012–2022) is changing according to age group and route of infection, highlighting the need for revised prevention and promotion policies. Full article

(This article belongs to the Special Issue Infectious Disease Prevention and Control: A One Health Approach)

9 pages, 328 KiB

Open AccessArticle

Clinical Prediction Rules for In-Hospital Mortality Outcome in Melioidosis Patients

by Sunee Chayangsu, Chusana Suankratay, Apichat Tantraworasin and Jiraporn Khorana

Trop. Med. Infect. Dis. 2024, 9(7), 146; https://doi.org/10.3390/tropicalmed9070146 - 28 Jun 2024

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Abstract

Background: Melioidosis, a disease induced by Burkholderia pseudomallei, poses a significant health threat in tropical areas where it is endemic. Despite the availability of effective treatments, mortality rates remain notably elevated. Many risk factors are associated with mortality. This study aims to [...] Read more.

Background: Melioidosis, a disease induced by Burkholderia pseudomallei, poses a significant health threat in tropical areas where it is endemic. Despite the availability of effective treatments, mortality rates remain notably elevated. Many risk factors are associated with mortality. This study aims to develop a scoring system for predicting the in-hospital mortality from melioidosis using readily available clinical data. Methods: The data were collected from Surin Hospital, Surin, Thailand, during the period from April 2014 to March 2017. We included patients aged 15 years and above who had cultures that tested positive for Burkholderia pseudomallei. The clinical prediction rules were developed using significant risk factors from the multivariable analysis. Results: A total of 282 patients with melioidosis were included in this study. In the final analysis model, 251 patients were used for identifying the significant risk factors of in-hospital fatal melioidosis. Five factors were identified and used for develo** the clinical prediction rules, and the factors were as follows: qSOFA ≥ 2 (odds ratio [OR] = 2.39, p= 0.025), abnormal chest X-ray findings (OR = 5.86, p < 0.001), creatinine ≥ 1.5 mg/dL (OR = 2.80, p = 0.004), aspartate aminotransferase ≥50 U/L (OR = 4.032, p < 0.001), and bicarbonate ≤ 20 mEq/L (OR = 2.96, p = 0.002). The prediction scores ranged from 0 to 7. Patients with high scores (4–7) exhibited a significantly elevated mortality rate exceeding 65.0% (likelihood ratio [LR+] 2.18, p < 0.001) compared to the low-risk group (scores 0–3) with a lower mortality rate (LR + 0.18, p < 0.001). The area under the receiver operating characteristic curve (AUC) was 0.84, indicating good model performance. Conclusions: This study presents a simple scoring system based on easily obtainable clinical parameters to predict in-hospital mortality in melioidosis patients. This tool may facilitate the early identification of high-risk patients who could benefit from more aggressive treatment strategies, potentially improving clinical decision-making and patient outcomes. Full article

14 pages, 3085 KiB

Open AccessArticle

Experimental Granulomatous Amebic Encephalitis Caused by Acanthamoeba castellanii

by Samuel da Luz Borges, Eberson da Silva de Macedo, Felipe Alexandre Vinagre da Silva, Brenda Jaqueline de Azevedo Ataíde, Nívia de Souza Franco Mendes, Adelaide da Conceição Fonseca Passos, Suellen Alessandra Soares de Moraes, Anderson Manoel Herculano, Karen Renata Herculano Matos Oliveira, Carlomagno Pacheco Bahia, Silvio Santana Dolabella and Evander de Jesus Oliveira Batista

Trop. Med. Infect. Dis. 2024, 9(7), 145; https://doi.org/10.3390/tropicalmed9070145 - 28 Jun 2024

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Abstract

Acanthamoeba genus can affect humans with diseases such as granulomatous amebic encephalitis (GAE), a highly lethal neuroinfection. Several aspects of the disease still need to be elucidated. Animal models of GAE have advanced our knowledge of the disease. This work tested Wistar rats [...] Read more.

Acanthamoeba genus can affect humans with diseases such as granulomatous amebic encephalitis (GAE), a highly lethal neuroinfection. Several aspects of the disease still need to be elucidated. Animal models of GAE have advanced our knowledge of the disease. This work tested Wistar rats (Rattus norvegicus albinus) as an animal model of GAE. For this, 32 animals were infected with 1 × 10⁶ A. castellanii trophozoites of the T4 genotype. Ameba recovery tests were carried out using agar plates, vascular extravasation assays, behavioral tests, and histopathological technique with H/E staining. Data were subjected to linear regression analysis, one-way ANOVA, and Tukey’s test, performed in the GraphPad Prism^® 8.0 program, with a significance level of p < 0.05. The results revealed the efficiency of the model. Amebae were recovered from the liver, lungs, and brain of infected animals, and there were significant encephalic vascular extravasations and behavioral changes in these animals, but not in the control animals. However, not all infected animals showed positive histopathology for the analyzed organs. Nervous tissues were the least affected, demonstrating the role of the BBB in the defense of the CNS. Supported by the demonstrated evidence, we confirm the difficulties and the feasibilities of using rats as an animal model of GAE. Full article

(This article belongs to the Special Issue Advances in Parasitic Neglected Tropical Diseases)

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12 pages, 222 KiB

Open AccessArticle

Challenges of Screening and Investigations of Contacts of Patients with Tuberculosis in Oyo and Osun States, Nigeria

by Aderonke Agbaje, Patrick Dakum, Olugbenga Daniel, Anyaike Chukwuma, Obioma Chijoke-Akaniro, Evaezi Okpokoro, Samuel Akingbesote, Christian Anyomi, Adekola Adekunle, Abiola Alege, Moroof Gbadamosi, Olutunde Babalola, Charles Mensah, Rupert Eneogu, Austin Ihesie and Ademola Adelekan

Trop. Med. Infect. Dis. 2024, 9(7), 144; https://doi.org/10.3390/tropicalmed9070144 - 28 Jun 2024

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Abstract

Tuberculosis (TB) remains a significant public health challenge in Nigeria, with high rates of transmission and low case detection rates. This paper presents the challenges of screening and investigation of contacts of patients with TB in Oyo and Osun State, Nigeria. This descriptive-qualitative [...] Read more.

Tuberculosis (TB) remains a significant public health challenge in Nigeria, with high rates of transmission and low case detection rates. This paper presents the challenges of screening and investigation of contacts of patients with TB in Oyo and Osun State, Nigeria. This descriptive-qualitative study was conducted in eight Local Government Areas with high TB burdens. Twenty-four focus group discussions and 30 key informant interviews were conducted among TB patients, household TB contacts, and government TB staff, among others. Respondents ages ranged from 17–85 years with a mean of 42.08 ± 14.9 years, and (4.0%) had a postgraduate degree. This study identified that the majority of TB contacts who tested negative for TB were unwilling to be placed on TB preventive therapy because of the belief that only a sick person should take drugs. Also, hostility from the TB contacts to the contact tracers during the house-to-house screening of presumptive TB cases due to community stigma associated with TB was another existing gap reported in TB contact investigations. The findings emphasise the importance of tailored approaches in TB prevention and control, addressing challenges in testing and contact investigations; this necessitates investments in community engagement strategies to enhance the cooperation of TB contacts. Full article

(This article belongs to the Section Infectious Diseases)

13 pages, 1090 KiB

Open AccessArticle

One Health Approach to Toxoplasmosis: Owner and Dog Seropositivity as Spatial Indicators of Risk Areas for Acquired, Gestational and Congenital Transmission

by Natacha Sohn-Hausner, Ricardo Guedes Correa, Louise Bach Kmetiuk, Evelyn Cristine da Silva, Gustavo Nunes de Moraes, Gabrielle dos Santos Rocha, Helio Langoni and Alexander Welker Biondo

Trop. Med. Infect. Dis. 2024, 9(7), 143; https://doi.org/10.3390/tropicalmed9070143 - 28 Jun 2024

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Abstract

Background: Toxoplasmosis has been of public health concern due to direct associations with socioeconomic vulnerability and inadequate living conditions. Methods: Accordingly, the present study aimed to assess antibodies against T. gondii, historical reported toxoplasmosis cases and associated socio-environmental risk factors in Pinhais, [...] Read more.

Background: Toxoplasmosis has been of public health concern due to direct associations with socioeconomic vulnerability and inadequate living conditions. Methods: Accordingly, the present study aimed to assess antibodies against T. gondii, historical reported toxoplasmosis cases and associated socio-environmental risk factors in Pinhais, a full urban area of Curitiba, currently the eighth biggest metropolitan area of Brazil. Anti-Toxoplasma gondii antibodies were assessed by an indirect immunofluorescence reaction (RIFI). Owner and dog samples were also tested by IFAT to anti-Leishmania spp. and anti-Trypanosoma cruzi antibodies. Results: Overall, 20/135 (14.8%) persons and 13/133 (9.8%) dogs from 25 different households were considered seropositive to T. gondii. All samples were seronegative to Leishmania spp. and Trypanosoma cruzi. Conclusions: Although no significant covariates were found in the regression model, statistically associated risk factors in the bivariate analysis included no public water use (p = 0.016) and drinking raw milk (p = 0.041) for owners, and obesity (p = 0.028) and tick infestation (p = 0.03) for dogs. In addition, a spatial cluster of T. gondii seropositivity for both owners and their dogs overlapped the location of historic reported cases of human acquired, gestational and congenital toxoplasmosis. Finally, the results herein showed tick infestation as an indicator of socio-environmental risk for T. gondii exposure in the household environment, and dogs may be used as sentinels for human toxoplasmosis cases. Full article

(This article belongs to the Section One Health)

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13 pages, 498 KiB

Open AccessArticle

Evaluation of Bait Acceptance and Immune Response in Local Dogs during an Oral Rabies Vaccination Field Study in Morocco

by Nadia Aboulfidaa, Florence Cliquet, Emmanuelle Robardet, Sami Darkaoui, Marine Wasniewski, Christian Kaiser, Katharina Bobe, Ad Vos and Ouafaa Fassi Fihri

Trop. Med. Infect. Dis. 2024, 9(7), 142; https://doi.org/10.3390/tropicalmed9070142 - 26 Jun 2024

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Abstract

The objective of this study was to evaluate the bait preference of three selected bait types by local dogs and the induced immunogenicity of the oral rabies vaccine strain SPBN GASGAS in Morocco. The vaccine strain, combined with different bait types, has been [...] Read more.

The objective of this study was to evaluate the bait preference of three selected bait types by local dogs and the induced immunogenicity of the oral rabies vaccine strain SPBN GASGAS in Morocco. The vaccine strain, combined with different bait types, has been tested in many different settings, but not yet in northern Africa. Overall, bait consumption and preference were similar in other studies using the same materials (bait type and sachet). The intestine bait had the highest acceptance rate (97.6%, 95%CI: 87.4–99.9), followed by the egg bait (83.0%, 95%CI: 69.2–92.4). Only 52% (95%CI: 37.4–66.3) of the dogs showed an interest in the fish meal bait. However, considering the successful release of the contents of the sachet (blue-dyed water) into the oral cavity, the egg bait (65.7%, 95%CI: 47.8–80.9) scored better than the intestine bait (51.7%, 95%CI: 32.5–70.6). The dogs selected for the immunogenicity study were offered the egg bait containing a sachet filled with SPBN GASGAS (3.0ml, 10^7.5 FFU/mL) or were given the same dose by direct oral administration (d.o.a.). In addition, several dogs were vaccinated by the parenteral route (s.c.) using a commercially available inactivated rabies vaccine. Unfortunately, due to the COVID-19 pandemic and subsequent travel restrictions, it was not possible to collect blood samples directly after vaccination. The blood samples were collected pre-vaccination and on five occasions between 450 and 1088 days post vaccination. The seroconversion rate, as determined for rabies-virus-neutralizing antibodies by the FAVN test, was significantly lower than that found for binding antibodies, as determined by ELISA, for all blood samples collected post vaccination. No treatment effect (bait, d.o.a., s.c.) could be seen in the seroconversion rate. At 15 months post vaccination, 84.2% of the dogs offered vaccine bait still tested sero-positive in ELISA. Only after 3 years was a clear drop in the seroconversion rate observed in all three treatment groups. This study confirms the long-term immunogenicity of the oral rabies vaccine SPBN GASGAS in dogs under field conditions. Full article

(This article belongs to the Special Issue Treatment and Risk Assessment of Rabies)

12 pages, 1316 KiB

Open AccessArticle

Consistency of Multi-Month Antiretroviral Therapy Dispensing and Association with Viral Load Coverage among Pediatric Clients Living with HIV in Mozambique

by Ivete Meque, Nicole Herrera, Michelle M. Gill, Rui Guilaze, Amancio Nhangave, Jaciara Mussá, Nilesh Bhatt, Mahoudo Bonou and Lauren Greenberg

Trop. Med. Infect. Dis. 2024, 9(7), 141; https://doi.org/10.3390/tropicalmed9070141 - 26 Jun 2024

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Abstract

With the increase in uptake of multi-month antiretroviral therapy dispensing (MMD) for children, little is known about consistency of MMD receipt over time and its association with virological outcomes. This analysis aims to assess the uptake of 3-month MMD among children, consistent receipt [...] Read more.

With the increase in uptake of multi-month antiretroviral therapy dispensing (MMD) for children, little is known about consistency of MMD receipt over time and its association with virological outcomes. This analysis aims to assess the uptake of 3-month MMD among children, consistent receipt of MMD after uptake, and clinical outcomes following transition to MMD in 16 health facilities in Gaza and Inhambane Provinces. This is a secondary analysis involving children <15 years living with HIV with clinical visits during the period from September 2019 to August 2020. Of 4383 children, 82% ever received MMD (at least one pickup of a 3-month MMD supply) during the study period but only 40% received it consistently (defined as MMD at every visit during the study period). Consistent MMD was most common among older children and children without indications of clinical instability. Overall viral load (VL) coverage was 40% (733/1851). Consistent MMD was significantly associated with lower odds of having a VL (0.78, 95% CI: 0.64–0.95). In conclusion, while receipt of a multi-month supply was common particularly during the early days of the COVID-19 pandemic, only a minority of children received consistent MMD; however, there is a need to ensure children with fewer visits still receive timely VL monitoring. Full article

(This article belongs to the Special Issue Living with HIV: Support, Care, and Treatment for Vulnerable Populations)

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16 pages, 1570 KiB

Open AccessArticle

Identification and Functional Implications of the E5 Oncogene Polymorphisms of Human Papillomavirus Type 16

by Antônio Humberto P. da Silva-Júnior, Ruany Cristyne de Oliveira Silva, Ana Pavla A. Diniz Gurgel, Marconi Rêgo Barros-Júnior, Kamylla Conceição Gomes Nascimento, Daffany Luana Santos, Lindomar J. Pena, Rita de Cássia Pereira Lima, Marcus Vinicius de Aragão Batista, Bárbara Simas Chagas and Antonio Carlos de Freitas

Trop. Med. Infect. Dis. 2024, 9(7), 140; https://doi.org/10.3390/tropicalmed9070140 - 26 Jun 2024

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Abstract

The persistence of the human papillomavirus type 16 (HPV16) infection on the cervical epithelium contributes to the progression of cervical cancer. Studies have demonstrated that HPV16 genetic variants may be associated with different risks of develo** cervical cancer. However, the E5 oncoprotein of [...] Read more.

The persistence of the human papillomavirus type 16 (HPV16) infection on the cervical epithelium contributes to the progression of cervical cancer. Studies have demonstrated that HPV16 genetic variants may be associated with different risks of develo** cervical cancer. However, the E5 oncoprotein of HPV16, which is related to several cellular mechanisms in the initial phases of the infection and thus contributes to carcinogenesis, is still little studied. Here we investigate the HPV16 E5 oncogene variants to assess the effects of different mutations on the biological function of the E5 protein. We detected and analyzed the HPV16 E5 oncogene polymorphisms and their phylogenetic relationships. After that, we proposed a tertiary structure analysis of the protein variants, preferential codon usage, and functional activity of the HPV16 E5 protein. Intra-type variants were grouped in the lineages A and D using in silico analysis. The mutations in E5 were located in the T-cell epitopes region. We therefore analyzed the interference of the HPV16 E5 protein in the NF-kB pathway. Our results showed that the variants HPV16E5_49PE and HPV16E5_85PE did not increase the potential of the pathway activation capacity. This study provides additional knowledge about the mechanisms of dispersion of the HPV16 E5 variants, providing evidence that these variants may be relevant to the modulation of the NF-κB signaling pathway. Full article

(This article belongs to the Special Issue Molecular Epidemiology of Human Papillomavirus Infection)

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11 pages, 3137 KiB

Open AccessArticle

Investigating the Diagnostic and Therapeutic Potential of a T Cell Receptor (TCR)-like single Domain Antibody (sDAb)-Human IgG1 Antibody against Heat Shock Protein (HSP) 16KDa/HLA-A2 for Latent Tuberculosis

by Huaqiang Liu, Sylvia Annabel Dass, Matthew Tze Jian Wong, Venugopal Balakrishnan, Fazlina Nordin and Gee Jun Tye

Trop. Med. Infect. Dis. 2024, 9(7), 139; https://doi.org/10.3390/tropicalmed9070139 - 26 Jun 2024

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Abstract

Heat shock protein 16-kDa (HSP 16-kDa) is essential for the survival of Mycobacterium tuberculosis (M. tuberculosis) during the latent period; hence, a peptide–MHC presentation of HSP 16-kDa could be a potential diagnostic and therapeutic target for latent tuberculosis (LTB). This study [...] Read more.

Heat shock protein 16-kDa (HSP 16-kDa) is essential for the survival of Mycobacterium tuberculosis (M. tuberculosis) during the latent period; hence, a peptide–MHC presentation of HSP 16-kDa could be a potential diagnostic and therapeutic target for latent tuberculosis (LTB). This study aimed to generate a TCR-like single-domain antibody (sDAb)-human IgG1 antibody and subsequently investigate its diagnostic and therapeutic potential in LTB, utilizing a model cell presenting the target peptide. A previously generated TCR-like sDAB that can bind to HSP 16-kDa was first fused to a human IgG1 Fc-receptor via a linker. The fusion product, sDAb-IgG1, was expressed with HEK293-F and was subsequently purified. Its diagnostic potential was investigated via cell-based ELISA utilizing MCF-7 cells peptide-pulsed with HSP 16-kDa peptides. Investigation into the antibody-dependent cell-mediated cytotoxicity (ADCC) of MCF-7 cells was also conducted to investigate its therapeutic potential. Finally, TCR-like sDAb-IgG1 was successfully produced transiently with HEK-293F and was purified using protein A chromatography. The generated antibody was tested using cell-based ELISA, which demonstrated the effective binding of the TCR-like sDAb-IgG1 to the 16-kDa peptide–MHC on the cell surface. The ADCC assay also showed that the antibody effectively mediated the ADCC of MCF-7 cells with the help of 16-kDa peptide–MHC. This allows us to hypothesize the possible utility of the said antibody for both diagnostics and therapeutics of latent tuberculosis after more investigations with clinical samples. Full article

(This article belongs to the Special Issue The Epidemiology, Diagnosis and Treatment of Mycobacteria Infection (including TB and NTM))

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Trop. Med. Infect. Dis., Volume 9, Issue 7 (July 2024) – 11 articles

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