The American Journal of Tropical Medicine and Hygiene - Current Issue

Burkholderia pseudomallei is a selective agent that causes septic melioidosis and exhibits a broad range of lethal doses in animals. Host cellular virulence and phagocytic resistance are pathologic keys of B. pseudomallei. We first proposed Caenorhabditis elegans as the host cellular virulence model to mimic bacterial virulence against mammals and second established the resistance of B. pseudomallei to predation by Dictyostelium discoideum as the phagocytosis model. The saprophytic sepsis–causing Burkholderia sp. (B. pseudomallei, Burkholderia thailandensis, Burkholderia cenocepacia, and Burkholderia multivorans) exhibited different virulence patterns in both simple models, but B. pseudomallei was the most toxic. Using both models, attenuated isolates of B. pseudomallei were selected from a transposon-mutant library and a panel of environmental isolates and reconfirmed by in vitro mouse peritoneal exudate cell association and invasion assays. The distinct pathological patterns of melioidosis were inducted by different selected B. pseudomallei isolates. Fatal melioidosis was induced by the isolates with high virulence in both simple models within 4–5 day, whereas the low-virulence isolates resulted in prolonged survival greater than 30 day. Infection with the isolates having high resistance to D. discoideum predation but a low C. elegans killing effect led to 83% of mice with neurologic melioidosis. By contrast, infection with the isolates having low resistance to D. discoideum predation but high C. elegans killing effect led to 20% cases with inflammation in the salivary glands. Our results indicated that individual B. pseudomallei isolates selected from simple biological models contribute differently to disease progression and/or tissue tropism.

Salmonella enterica serovar Infantis is causing an increasing number of infections worldwide. Our aim was to describe the characteristics of S. enterica serovar Infantis among patients attended in a hospital of Lima, Peru. Fifty cases of salmonellosis were seen during October 2015–May 2017; Salmonella Infantis was detected in 36% (n = 18) of them, displacing Enteritidis and Typhimurium (n = 13, 26%, each). Seventeen cases caused by Salmonella Infantis were presented as diarrheal illnesses; only one extraintestinal case (bacteremia) was seen in a 1-year-old infant. This serovar is resistant to multiple groups of antimicrobials, showing only fully susceptibility to carbapenems. Compared with Infantis, other serovars analyzed (mainly Enteritidis and Typhimurium) showed a lower frequency of resistance to antimicrobials such as trimethoprim–sulfamethoxazole, ampicillin, and chloramphenicol. The antibiotic with the highest frequency of resistance was ciprofloxacin. Further studies are needed to evaluate the routes of transmission and measures of control of this multidrug-resistant Salmonella.

Bartonellae are emerging vector-borne pathogens infecting various domestic and wild mammals. Blood samples were collected from 66 dogs at two locations near Hamedan, Iran. Twenty dogs were rescued stray dogs and 46 dogs were from a breeding colony, with many of them infested with fleas, ticks, or lice. Serology was performed using an indirect immunofluorescent antibody test for Bartonella henselae, Bartonella clarridgeiae, and Bartonella vinsonii subsp. berkhoffii. Seroprevalence was 74.2% (range: 65.2–95%). Bartonella DNA amplification and sequencing identified B. vinsonii subsp. berkhoffii type III in seven dogs, including five rescued dogs. Two dogs were infected with Bartonella rochalimae and three dogs with Candidatus B. merieuxii, including two of the stray dogs coinfected with Bartonella vinsonii subsp. berkhoffii. Rescued stray dogs were 10 times (odds ratio (OR) = 10.13, 95% CI: 1.24–82.7; P = 0.03) more likely to be seropositive and eight times (OR = 8.82, 95% CI: 2.68–29.11; P = 0.0004) more likely to be flea-infested than breeding dogs, confirming that arthropod infestation is a major risk factor for these infections.

The “Top End” of Australia is presently experiencing a gonorrhea epidemic. Gonococcal infection is usually limited to mucosal tissues but can lead to disseminated gonococcal infection (DGI), joint destruction, and severe sepsis. This study aimed to explore the epidemiology, presentation, management, and health-care impact of DGI in the Top End of the Northern Territory. Health records of patients diagnosed with proven, probable, or possible DGI between January 2010 and September 2018 were analyzed retrospectively. One hundred six cases of DGI were identified. Ninety-four patients (88.7%) were Indigenous Australian. The incidence of proven and probable DGI in the Indigenous population was 27.1 per 100,000 person-years, compared with 7.1 in the Top End population overall. Of 7,540 laboratory-proven gonococcal notifications, 1.3% (n = 97) were complicated by DGI. The highest incidence was in the 15–19-year age-group. Thirteen cases (12.3%) occurred in patients younger than 15 years. High rates of comorbid alcohol misuse, diabetes, systemic lupus erythematosus, rheumatic fever, and complement deficiency were observed. The “classic triad” of tenosynovitis, dermatitis, and polyarthralgia was rare. Ninety-four patients (88.7%) presented with purulent arthritis. Disseminated gonococcal infection was estimated to cause at least 10.0% of nonpenetrating septic arthritis in the Top End and 1,234 days of hospitalization during the study period. DGI is an important cause of morbidity in the Top End, particularly in the young, remote Indigenous Australian population. Clinical presentation varies from classical teaching. Urgent action in the health and community sector is required, particularly for at-risk populations, to prevent further debilitating and costly complications of gonococcal infection.

In Brazil, the reported number of syphilis cases among pregnant women has markedly increased. We conducted a cross-sectional study to determine the prevalence of Treponema pallidum infection and associated factors in pregnant women in Dourados, Mato Grosso do Sul, Brazil. Participants voluntarily completed a risk-factor questionnaire and provided blood specimens for unlinked anonymous testing for the presence of antibodies against T. pallidum, the causative agent of syphilis. Data of newborns were obtained from medical records. We performed univariate and multivariate regression analyses to assess associations with syphilis. The seroprevalence of syphilis in pregnant women was 4.4% (n = 29/661). Twenty-five newborns were seropositive for T. pallidum, and complications due to syphilis were observed in 28% (n = 7/25). Although 96.5% (n = 28/29) of women with syphilis received antenatal care, Venereal Disease Research Laboratory tests were performed in the first trimester for 47.6% (n = 10/21) of women. Women who received treatment in the third trimester (28.6%; n = 6/21) were considered successfully treated at the time of delivery. The use of illicit drugs during pregnancy (odds ratio [OR]: 13.3, 95% CI: 1.9–91.2) and a history of abortion (OR: 3.7, 95% CI: 1.7–8) were associated with syphilis. Our findings highlight that the poor quality of antenatal care services contributes to the high prevalence of syphilis. In addition, there are social and behavioral risk factors associated with syphilis in pregnant women. Future studies are needed to determine limitations of clinical management and control services available to pregnant women with syphilis.

Trachoma is the leading infectious cause of blindness, and facial cleanliness is associated with reduced odds of trachomatous inflammation and Chlamydia trachomatis infection, but there is little evidence of how to drive this behavior change at scale. We report the results of a program integrating face washing into a school-based handwashing promotion program in Turkana County, Kenya. Children aged 5–15 years participated in an intervention delivered to schools in two phases, along with a third phase receiving the intervention after the evaluation, which served as a control. The primary outcome was the number of face washing events that took place when handwashing occurred, which was measured by a 3-hour structured observation at all 67 schools, and a total of 3,871 handwashing events were observed. Differences in observed in face washing behavior between each phase and the control schools were calculated using log-binomial regression with clustering at the school level, whereas survey responses on knowledge of trachoma transmission and prevention were compared using χ2 tests adjusted for clustering at the school level. Face washing during handwashing events was higher in schools after 12 months (59.3%) and 20 months (44.2%) than in control schools (18.7%, P < 0.001). Trachoma knowledge was higher in schools evaluated after 12 months (80%) and 20 months (70%) than in control schools (42%, P < 0.001), and knowledge of some of key preventive behaviors was higher in intervention schools. Integrating face washing messages into school-based handwashing promotion programs increased face washing, which may help to prevent trachoma when combined with other interventions.

National border areas are special places for the spread of Mycobacterium tuberculosis (MTB). These regions concentrate vulnerable populations and constant population movements. Understanding the dynamics of the transmission of MTB is fundamental to propose control measures and to monitor drug resistance. We conducted a population-based prospective study of tuberculosis (TB) to evaluate molecular characteristics of MTB isolates circulating in Roraima, a state on the border of Venezuela and Guyana. Eighty isolates were genotyped by IS6110-RFLP (restriction fragment length polymorphism), spoligotyping, and 24-locus mycobacterial interspersed repetitive unit-variable number of repeats tandem (MIRU-VNTR). Drug susceptibility tests were performed by using the proportion method and GeneXpert® MTB/RIF (Cepheid, Sunnyvale, CA). Isolates showing a phenotypic resistance profile were submitted to polymerase chain reaction (PCR) and sequencing. Spoligotyping showed 40 distinct patterns with a high prevalence of Latin-American and Mediterranean (LAM), Haarlem (H), and the “ill-defined” T clades. Mycobacterial interspersed repetitive unit -VNTR and IS6110-RFLP showed clustering rates of 21.3% and 30%, respectively. Drug resistance was detected in 11 (15.1%) isolates, and all were found to have primary resistance; among these, six (8.2%) isolates were streptomycin mono-resistant, four (5.4%) isoniazid mono-resistant, and one (1.3%) multidrug resistant. This is the first study on the molecular epidemiology and drug resistance profile of MTB from Roraima. Herein, we describe high diversity of genetic profiles circulating in this region that may be driven by the introduction of new strain types because of large population flow in this region. In summary, our results showed that analyses of these circulating strains can contribute to a better understanding of TB epidemiology in the northern Brazilian border and be useful to establish public health policies on TB prevention.

American tegumentary leishmaniasis is an endemic anthropozoonosis undergoing expansion on the American continent. The disease is caused by several Leishmania species and it is manifested as cutaneous and mucocutaneous leishmaniasis. In this study, we evaluate the viability of high-resolution melt polymerase chain reaction (HRM-PCR) analysis to differentiate four closely related Leishmania species as a routine tool for the diagnosis of leishmaniasis. For this purpose, biopsy specimens from cutaneous and mucocutaneous lesions were taken from 132 individuals from endemic and non-endemic areas for leishmaniasis. Each sample was processed for parasitological, histopathological, and molecular analysis. Positive biopsy samples were analyzed by HRM-PCR of a 144-bp heat-shock protein (hsp70) gene fragment, and new cases were confirmed by sequencing. Of the 132 samples analyzed, 36 (27%) were positive for Leishmania spp., of which 86% were from cutaneous lesions and 14% from mucocutaneous lesions. We identified Leishmania (Viannia) braziliensis (84%), Leishmania (Leishmania) infantum (13%), and Leishmania (Leishmania) amazonensis (3%) in cutaneous lesions, and L. (V.) braziliensis (40%), L. (L.) infantum (20%), L. (L.) amazonensis (20%), and Leishmania (Viannia) guyanensis (20%) in mucocutaneous lesions. The main purpose of this research was to report for the first time in Paraguay the presence of L. (L.) amazonensis and L. (V.) guyanensis in patients with cutaneous and mucocutaneous lesions, using the HRM-PCR technique. In addition, we report the presence of additional new cases of L. (L.) infantum in cutaneous lesions.

In India, visceral leishmaniasis (VL) caused by Leishmania donovani has been successfully treated with miltefosine with a cure rate of > 90%. To assess the efficacy and safety of oral miltefosine against Brazilian VL, which is caused by Leishmania infantum, a phase II, open-label, dose-escalation study of oral miltefosine was conducted in children (aged 2–12 years) and adolescent-adults (aged 13–60 years). Definitive cure was assessed at a 6-month follow-up visit. The cure rate was only 42% (6 of 14 patients) with a recommended treatment of 28 days and 68% (19 of 28 patients) with an extended treatment of 42 days. The in vitro miltefosine susceptibility profile of intracellular amastigote stages of the pretreatment isolates, from cured and relapsed patients, showed a positive correlation with the clinical outcome. The IC50 mean (SEM) of eventual cures was 5.1 (0.4) µM, whereas that of eventual failures was 12.8 (1.9) µM (P = 0.0002). An IC50 above 8.0 µM predicts failure with 82% sensitivity and 100% specificity. The finding of L. infantum amastigotes resistant to miltefosine in isolates from patients who eventually failed treatment strongly suggests natural resistance to this drug, as miltefosine had never been used in Brazil before this trial was carried out.

Liposomal amphotericin B (LAmB) is recommended for treatment of Indian visceral leishmaniasis (VL), with a cure rate of more than 95% in the Indian subcontinent. A prospective observational study of 1,143 subjects was performed with a longer follow-up than prior studies (12 months) to evaluate the long-term effectiveness and safety of LAmB for the treatment of VL. Patients received a single dose of 10 mg/kg LAmB and were evaluated for initial cure at day 30 and final cure at 6 and 12 months to see the response to the therapy. Furthermore, predictors of relapse were also calculated. At day 30, the initial cure rate was 100%; however, at 6 months and 12 months, cure rates were 97.0% and 94.2% by per-protocol analysis and 96.9% and 93.9% by intension-to-treat analysis, respectively. Fever was the most common adverse event (AE). There were no deaths and serious AEs. Male gender, weight less than 30 kg, and spleen size more than 4 cm at the start of the treatment were significant risk factors of relapse. Liposomal amphotericin B was found to be very effective and safe in the treatment of VL. A longer follow-up period of 12 months is recommended to pick up late relapses.

We explored spatial variation in the prevalence of established molecular markers of antimalarial resistance across a geographically diverse, highland region of western Uganda. We identified Plasmodium falciparum CQ resistance transporter 76T mutations in all pools, but there was no evidence of spatial differences across village-based strata defined by either altitude or river valley. In contrast, we identified a significant inverse association between altitude and the prevalence of Plasmodium falciparum multidrug resistance 1 mutations with the largest proportion of Y184F mutations observed in the low-elevation, high-transmission villages. These results demonstrate the substantial heterogeneity in resistance markers observed across geographic settings, even at relatively small scales, but highlight the complex nature of these ecological relationships.

Splenic infarction caused by malaria can be fatal, but its incidence and clinical presentation are not well-known. Thus, we investigated the prevalence and characteristics of splenic complications in patients with vivax malaria from 2005 to 2017 in a university hospital. Among 273 patients who were diagnosed with Plasmodium vivax infection by blood smear, 92 underwent abdominal computed tomography or ultrasonography. Twelve patients had splenic infarction. All patients with splenic infarction recovered after treatment with antimalarial drugs, without surgery and intervention. Although anemia and prolonged fever may be risk factors for splenic infarction, the incidence of these events was insufficient for a detailed analysis.

Intermittent preventive treatment with sulfadoxine–pyrimethamine (SP) is recommended to prevent malaria in pregnancy. Treatment coverage, particularly for three or more doses, is dependent on pregnant women attending antenatal care (ANC) services as scheduled. The StopPalu project pilot tested short message services (SMSs) to remind women of upcoming ANC visits in the Conakry and Kindia regions of Guinea. Health facilities were selected as pilot and comparison facilities. All women who attended an initial ANC visit at a selected facility during the pilot period and had access to a mobile telephone were enrolled. The pilot group was sent an SMS before each appointment. Percentage of attendance and SP distribution were calculated. A log-binomial regression model determined odds ratios. Pregnant women receiving SMS were 48 times more likely to attend all visits and were 12 times more likely to receive all SP doses during pregnancy.

A substantial decline of malaria transmission intensity has been observed in sub-Saharan Africa over the past two decades and may affect the diagnostic performance of malaria rapid diagnostic test (mRDT) and microscopy. Diagnostic performance of histidine-rich protein II (HRP-II)/pan-lactate dehydrogenase (pLDH)–based mRDT and microscopy was evaluated against polymerase chain reaction (PCR) for the diagnosis of Plasmodium falciparum infection among 316 primary schoolchildren in Kibiti district, in 2016. Polymerase chain reaction detected more cases of P. falciparum infection than mRDT or microscopy. Using PCR as reference, the sensitivity and specificity of mRDT were 75.9% (95% CI = 62.8–86.1) and 96.9% (95% CI = 94.0–98.7), respectively, whereas that of microscopy were 63.8% (95% CI = 50.1–76.0) and 95.7% (95% CI = 92.5–97.9), respectively. Polymerase chain reaction and other molecular methods should be considered for use in schools and other epidemiological surveys as supplement to mRDT or microscopy.

Calcified neurocysticercosis (NCC), previously thought to be a dead end, is an important risk factor for seizure recurrences. We studied the pattern of seizure recurrences and associated radiological findings in children with calcified NCC. In this ambispective cohort study, we enrolled children (age 1–15 years) with calcified NCC attending the pediatric NCC clinic between January 2017 and December 2017. Retrospective data were collected from the hospital records, and all enrolled children were prospectively followed up till June 2018. The study group divided into two groups: 1) children first presenting with calcified granuloma and 2) children presented with ring-enhancing lesion (REL) and transformed into the calcified lesion during follow-up imaging. During the study period (January 2017–December 2017), 520 children with NCC were screened and 128 with calcified NCC were enrolled. The mean age was 10.8 ± 3.2 years, and 63% were boys. Among 128 children, 40 (31%) had calcified granuloma and 88 (69%) had REL transformed to calcified granuloma. Sixty-one (49%) children had seizure recurrence: 22 (58%) within calcified granuloma group and 39 (45%) within REL transformed to calcified granuloma group (P = 0.18). Seizure recurrence was associated with the presence of perilesional edema (PE) in 35 (57.4%) children on computed tomography scan. The median interval between two seizure recurrences was 30 (17–56) months, and the median antiepileptic drug-free interval was 17 (12–22) months. The total duration of continued seizures was 42 (26–58) months, slightly longer in children with REL transformed to calcified granuloma group (42, 95% CI: 18–66 months) in comparison to calcified granuloma group (35, 95% CI: 10–60 months, P = 0.32). To conclude, children with calcified NCC have seizure recurrences over a prolonged period. Seizure recurrences are intermittent and may be interspersed with a prolonged period of quiescence in between. The presence of PE and contrast enhancement around the lesion during seizure recurrence suggests lesion reactivation.