The American Journal of Tropical Medicine and Hygiene - Volume 98, Issue 3, 2018

Anemia is a major public health problem that affects mainly children, predominantly in low-income countries and most often due to iron deficiency (ID). Administration of iron supplements to prevent and treat ID anemia in malaria endemic areas has been controversial for decades; however, recent World Health Organization guidelines recommend universal iron supplementation for children in highly prevalent anemia settings, including those where malaria is endemic. However, infants younger than 6 months of age have been exempted from this recommendation because ID is not considered prevalent at this age and because of assumptions—without evidence—that they are protected from ID through breast milk. To achieve full impact of anemia prevention targeting infants less than 6 months of age who are at highest risk of ID, operational studies that conclusively demonstrate the effectiveness and safety of delivering iron supplements to young infants in settings with a high burden of infectious diseases, including malaria, are needed.

Controlling and ultimately ending tuberculosis (TB) as a public health scourge will require a multifaceted and comprehensive approach involving the intensification of public health efforts, including scaling-up the delivery of current diagnostic, preventive, and therapeutic tools. However, a critically important element in the effort to end TB is an accelerated biomedical research effort to address the many unanswered questions about the disease process itself and to develop improved and innovative countermeasures. An intensive effort toward these research goals will facilitate the achievement of the aspirational goal of ending TB.

Trypanosoma cruzi is a protozoan of great importance to public health: it has infected millions of people in the world and is the etiologic agent of Chagas disease, which can cause cardiac and gastrointestinal disorders in patients and may even lead to death. The main vector of transmission of this parasite is triatomine bugs, which have a habit of defecating while feeding on blood and passing the parasite to their own hosts through their feces. Although it has been argued that T. cruzi is not pathogenic for this vector, other studies indicate that the success of the infection depends on several molecules and factors, including the insect’s intestinal microbiota, which may experience changes as a result of infection that include decreased fitness. Moreover, the effects of infection depend on the insect species, the parasite strain, and environmental conditions involved. However, the parasite–vector interaction is still underexplored. A deeper understanding of this relationship is an important tool for discovering new approaches to T. cruzi transmission and Chagas disease.

Severe congenital malaria associated with Plasmodium vivax is uncommon. In Indonesia, most congenital malaria cases are due to Plasmodium falciparum infections. Most cases of congenital or neonatal malaria in endemic areas are diagnosed from peripheral smear as part of routine sepsis workup. Differentiating congenital and acquired neonatal malaria is very difficult. The case presented in this study describes severe P. vivax malaria with cholestatic jaundice and sepsis-like signs and symptoms in neonates. The mother was asymptomatic and the neonate was successfully treated with intravenous artesunate. Severe P. vivax malaria with cholestatic jaundice in neonates is an uncommon condition that should be included in the differential diagnosis of infants displaying hemolytic anemia, thrombocytopenia, cholestatic jaundice, and hepatosplenomegaly in malaria-endemic zones. Early diagnosis can prevent the use of unnecessary antibiotics and mortality of neonates.

In 2013, the under-5 mortality rate in Liberia was 71 deaths per 1,000 live births, with malaria responsible for 22% of those deaths. One of the primary existing control tools, long-lasting insecticide-treated bed nets (LLINs), is thought to be dually effective, acting as a physical barrier but also decreasing the mosquito population in communities. However, there has been little investigation into the protective effects of community-wide bed net use above and beyond the individual level. Using data from the population-representative 2011 Liberia Malaria Indicator Survey, we estimated the association between proportion of a community using LLINs and malaria in children using multi-level logistic regression. To investigate the potential effect measure modification of the relationship by urbanicity, we included an interaction term and calculated stratum-specific prevalence odds ratios (PORs) for rural and urban communities. We calculated a POR of malaria for an absolute 10% increase in community bed net use of 1.13 (95% confidence interval [CI]: 0.91, 1.41) and 0.35 (95% CI: 0.13, 0.92) for rural and urban communities, respectively, indicating a strong, though imprecise, protective effect within urban communities only. Our results indicate that bed net use has an indirect protective effect in urban areas, above and beyond individual use. Little or no such effect of community-wide use is seen in rural areas, likely because of population density factors. Therefore, although all control efforts should be multifaceted, promotion of bed net use in urban areas in particular will likely be a highly effective tool for control.

The genetic diversity of glutamate-rich protein (GLURP) R2 region in Plasmodium falciparum isolates collected before and 12 years after the introduction of artemisinin combination treatment of malaria in Osogbo, Osun State, Nigeria, was compared in this study. Blood samples were collected on filter paper in 2004 and 2015 from febrile children from ages 1–12 years. The R2 region of the GLURP gene was genotyped using nested polymerase chain reaction and by nucleotide sequencing. In all, 12 GLURP alleles were observed in a total of 199 samples collected in the two study years. The multiplicity of infection (MOI) marginally increased over the two study years; however, the differences were statistically insignificant (2004 samples MOI = 1.23 versus 2015 samples MOI = 1.47). Some alleles were stable in their prevalence, whereas two GLURP alleles, VIII and XI, showed considerable variability between both years. This variability was replicated when GLURP sequences from other regions were compared with ours. The expected heterozygosity (He) values (He = 0.87) were identical for the two groups. High variability in the rearrangement of the amino acid repeat units in the R2 region were observed, with the amino acid repeat sequence DKNEKGQHEIVEVEEILPE more prevalent in both years, compared with the two other repeat sequences observed in the study. The parasite population characterized in this study displayed extensive genetic diversity. The detailed genetic profile of the GLURP R2 region has the potential to help guide further epidemiological studies aimed toward the rational design of novel chemotherapies that are antagonistic toward malaria.

Dihydroartemisinin–piperaquine (DHP) has been the first-line treatment of uncomplicated malaria due to both Plasmodium falciparum and Plasmodium vivax infections in Papua, Indonesia, since March 2006. The efficacy of DHP was reassessed to determine whether there had been any decline following almost a decade of its extensive use. An open-label drug efficacy study of DHP for uncomplicated P. falciparum and P. vivax malaria was carried out between March 2015 and April 2016 in Timika, Papua, Indonesia. Patients with uncomplicated malaria were administered supervised DHP tablets once daily for 3 days. Clinical and laboratory data were collected daily until parasite clearance and then weekly for 6 weeks. Molecular analysis was undertaken for all patients with recurrent parasitemia. A total of 129 study patients were enrolled in the study. At day 42, the polymerase chain reaction-adjusted efficacy was 97.7% (95% confidence intervals [CI]: 87.4–99.9) in the 61 patients with P. falciparum malaria, and 98.2% [95% CI: 90.3–100] in the 56 patients with P. vivax malaria. By day 2, 98% (56/57) of patients with P. falciparum and 96.9% (63/65) of those with P. vivax had cleared their peripheral parasitemia; none of the patients were still parasitaemic on day 3. Molecular analysis of P. falciparum parasites showed that none (0/61) had K13 mutations associated previously with artemisinin resistance or increased copy number of plasmepsin 2–3 (0/61). In the absence of artemisinin resistance, DHP has retained high efficacy for the treatment of uncomplicated malaria despite extensive drug pressure over a 9-year period.

The clinical epidemiology of severe malaria among patients presenting to peripheral health centers has not been well described. We conducted a prospective, observational cohort study to describe the epidemiology and clinical manifestations of severe malaria in a highland area of declining transmission intensity in Western Uganda. Individuals presenting with a history of fever were screened with a malaria rapid diagnostic test (RDT). We prepared blood smears and conducted clinical and laboratory testing for those with a positive RDT. We defined severe malaria in accordance with World Health Organization guidelines for research and epidemiological studies. A total of 6,641 individuals underwent testing for malaria. Ninety-six of 1,462 (6.6%) participants with confirmed parasitemia satisfied the criteria for severe malaria. The incidence of severe malaria peaked between 2 and 3 years of age (incidence rate ratio = 17.1, 95% confidence interval = 8.4–34.9, P < 0.001) and then declined steadily until age 10. However, we also found a second peak among those ≥ 50 years of age. Severe anemia was uncommon, detected in only 5.3% of cases. Instead, shock (22.2%) and lactic acidosis (19.4%) were most frequently encountered. Our results suggest that the clinical characteristics of severe malaria presenting to rural, peripheral health centers may be different than previously observed in referral centers. These findings merit further investigation into the optimal methods for identification and management of severe malaria in rural health centers in the region.

Antimalarial drug resistance has threatened global malaria control since chloroquine (CQ)-resistant Plasmodium falciparum emerged in Asia in the 1950s. Understanding the impacts of changing antimalarial drug policy on resistance is critical for resistance management. Plasmodium falciparum isolates were collected from 2003 to 2015 in western Kenya and analyzed for genetic markers associated with resistance to CQ (Pfcrt), sulfadoxine–pyrimethamine (SP) (Pfdhfr/Pfdhps), and artemether–lumefantrine (AL) (PfKelch13/Pfmdr1) antimalarials. In addition, household antimalarial drug use surveys were administered. Pfcrt 76T prevalence decreased from 76% to 6% from 2003 to 2015. Pfdhfr/Pfdhps quintuple mutants decreased from 70% in 2003 to 14% in 2008, but increased to near fixation by 2015. SP “super resistant” alleles Pfdhps 581G and 613S/T were not detected in the 2015 samples that were assessed. The Pfmdr1 N86-184F-D1246 haplotype associated with decreased lumefantrine susceptibility increased significantly from 4% in 2005 to 51% in 2015. No PfKelch13 mutations that have been previously associated with artemisinin resistance were detected in the study populations. The increase in Pfdhfr/Pfdhps quintuple mutants that associates with SP resistance may have resulted from the increased usage of SP for intermittent preventative therapy in pregnancy (IPTp) and for malaria treatment in the community. Prevalent Pfdhfr/Pfdhps mutations call for careful monitoring of SP resistance and effectiveness of the current IPTp program in Kenya. In addition, the commonly occurring Pfmdr1 N86-184F-D1246 haplotype associated with increased lumefantrine tolerance calls for surveillance of AL efficacy in Kenya, as well as consideration for a rotating artemisinin-combination therapy regimen.

The aim of this study was to develop a recombinase polymerase amplification (RPA) combined with a lateral flow (LF) strip method for specific diagnosis of Plasmodium knowlesi. With incubation at 37°C, the 18S rRNA gene of P. knowlesi was successfully amplified within 12 minutes. By adding a specifically designed probe to the reaction solution, the amplified RPA product can be visualized on a LF strip. The RPA assay exhibited high sensitivity with limits of detection down to 10 parasites/μL of P. knowlesi. Nonetheless, it was demonstrated that all P. knowlesi (N = 41) and other Plasmodium sp. (N = 25) were positive while negative samples (N = 8) were negative. Therefore, a combination of RPA and LF strip detection is a highly promising approach with the potential to be suitable for use in resource-limited settings.

Vector control programs, particularly in the form of insecticide-treated bed nets (ITNs), are essential for achieving malaria elimination goals. Recent reports of increasing knockdown resistance (kdr) mutation frequencies for Anopheles arabiensis in Western Kenya heightens the concern on the future effectiveness of ITNs in Kenya. We examined resistance in An. arabiensis populations across Kenya through kdr mutations and World Health Organization–recommended bioassays. We detected two kdr alleles, L1014F and L1014S. Kdr mutations were found in five of the 11 study sites, with mutation frequencies ranging from 3% to 63%. In two Western Kenya populations, the kdr L1014F allele frequency was as high as 10%. The L1014S frequency was highest at Chulaimbo at 55%. Notably, the kdr L1014F mutation was found to be associated with pyrethroid resistance at Port Victoria, but kdr mutations were not significantly associated with resistance at Chulaimbo, which had the highest kdr mutation frequency among all sites. This study demonstrated the emerging pyrethroid resistance in An. arabiensis and that pyrethroid resistance may be related to kdr mutations. Resistance monitoring and management are urgently needed for this species in Kenya where resistance is emerging and its abundance is becoming predominant. Kdr mutations may serve as a biomarker for pyrethroid resistance in An. arabiensis.

Pyrethroid resistance has been detected in Triatoma infestans (Hemiptera: Reduviidae), which was atributed to target site insensitivity and increased oxidative metabolism of the insecticide by cytochrome P450s. Nicotinamide adenine dinucleotide phosphate (NADPH) cytochrome P450 reductase (CPR) plays an essential role in transferring electrons from NADPH to the P450-substrate complex. In this study, the full length CPR cDNA of T. infestans was isolated and gene expression was determined by quantitative polymerase chain reaction. The open reading frame is 2,046 bp long, encoding a protein of 682 amino acids. Amino acid sequence analysis indicates that the T. infestans CPR and the putative Rhodnius prolixus and Triatoma dimidiata CPRs present conserved ligand-binding domains. Congruent with a previous study of our laboratory, in which the expression of three cytochrome P450 genes (CYP4EM7, CYP3085B1, and CYP3092A6 genes) was induced by deltamethrin, the levels of T. infestans CPR mRNA were upregulated in the fat body of fifth instar nymphs after topical application of deltamethrin. Besides, as it was observed in the CYP4EM7 gene, it was detected overexpression of the CPR gene in the most resistant strain of T. infestans included in the study. These results suggest that CPR plays an essential role in P450-mediated resistance of T. infestans to insecticides.

Achalasia is a motility disorder of the esophagus that might be secondary to a chronic Trypanosoma cruzi infection. Several studies have investigated esophageal achalasia in patients with Chagas disease (CD) in Latin America, but no related studies have been performed in Colombia. The goals of the present study were to determine the presence of anti-T. cruzi antibodies in patients with esophageal achalasia who visited a referral hospital in Bogotá, Colombia, and to detect the presence of the parasite and its discrete typing units (DTUs). This cross-sectional study was conducted in adult patients (18–65 years old) who were previously diagnosed with esophageal achalasia and from whom blood was drawn to assess antibodies against T. cruzi using four different serological tests. Trypanosoma cruzi DNA was detected by conventional polymerase chain reaction (cPCR) and quantitative polymerase chain reaction (qPCR). In total, 38 patients, with an average age of 46.6 years (standard deviation of ±16.2) and comprising 16 men and 22 women, were enrolled. Five (13.15%) patients were found to be positive for anti-T. cruzi antibodies by indirect immunofluorescence assay (IFA), and two patients who were negative according to IFA were reactive by both enzyme-linked immunosorbent assay and immunoblot (5.3%). Parasite DNA was detected in two of these seven patients by cPCR and in one of these by qPCR. The parasite DTU obtained was TcI. In summary, this study identified T. cruzi in Colombian patients with esophageal achalasia, indicating that digestive compromise could also be present in patients with chronic CD.

Although not presently implicated as a vector of human pathogens, the common bed bug, Cimex lectularius, has been suspected of carrying human pathogens because of its close association with humans and its obligate hematophagy. Recently, we characterized the vectorial competence of C. lectularius for the parasite Trypanosoma cruzi, the causative agent of Chagas disease. We observed that C. lectularius can acquire T. cruzi infection when fed on T. cruzi–carrying mice, and subsequently transmit T. cruzi to uninfected mice. This led us to ask why has C. lectularius not been implicated in the transmission of T. cruzi outside of the laboratory? We hypothesized that T. cruzi reduces C. lectularius fitness (i.e., survival and/or reproduction) as an explanation for why C. lectularius does not to transmit T. cruzi in natural settings. We tested this hypothesis by comparing the survival and reproduction of uninfected and T. cruzi–infected C. lectularius. We observed that T. cruzi had a variable effect on C. lectularius survival and reproduction. There were negligible differences between treatments in juveniles. Infected adult females tended to live longer and produce more eggs. However, no effect was consistent, and infected bugs showed more variation in survival and reproduction metrics than control bugs. We did not observe any negative effects of T. cruzi infection on C. lectularius survival or reproduction, suggesting that decreased fitness in T. cruzi–infected C. lectularius is not why bed bugs have not been observed to transmit T. cruzi in natural settings.

Chagas disease (CD) affects > 6 million people globally, including > 300,000 in the United States. Although early detection and etiological treatment prevents chronic complications from CD, < 1% of U.S. cases have been diagnosed and treated. This study explores access to etiological treatment from the perspective of patients with CD. In semi-structured interviews with 50 Latin American–born patients of the Center of Excellence for Chagas Disease at the Olive View–UCLA Medical Center, we collected demographic information and asked patients about their experiences managing the disease and accessing treatment. Patients were highly marginalized, with 63.4% living below the U.S. poverty line, 60% lacking a high school education, and only 12% with private insurance coverage. The main barriers to accessing health care for CD were lack of providers, precarious insurance coverage, low provider awareness, transportation difficulties, and limited time off. Increasing access to diagnosis and treatment will not only require a dramatic increase in provider and public education, but also development of programs which are financially, linguistically, politically, and geographically accessible to patients.

Reactivation of Chagas disease in the chronic phase may occur after solid organ transplantation, which may result in high parasitemia and severe clinical manifestations such as myocarditis and meningoencephalitis. The aim of the present study is to describe the prevalence of Chagas disease among solid organ–transplanted patients in a tertiary hospital from a nonendemic country. A cross-sectional study was performed at Vall d’Hebron University Hospital (Barcelona, Spain) from April to September 2016. Chagas disease screening was performed through serological tests in adult patients coming from endemic areas that had received solid organ transplantation and were being controlled in our hospital during the study period. Overall, 42 patients were included, 20 (47.6%) were male and median age was 50.5 (23–73) years. Transplanted organs were as follows: 18 kidneys, 17 lungs, and 7 livers. Three patients had Chagas disease, corresponding to a prevalence among this group of solid organ–transplanted patients of 7.1%. All three patients were born in Bolivia, had been diagnosed with Chagas disease and received specific treatment before the organ transplantation. We highly recommend providing screening tests for Chagas disease in patients with or candidates for solid organ transplantation coming from endemic areas, early treatment with benznidazole, and close follow-up to prevent clinical reactivations.

There has been a scarcity of data on the effect of health care on the quality of life (QoL) of human immunodeficiency virus (HIV)– and visceral leishmaniasis (VL)– coinfected patients over time. We sought to assess the change that health care brings about in the QoL of HIV patients with and without VL and its predictors in 6 months. A total of 465 HIV patients without VL and 125 HIV–VL-coinfected patients were enrolled in the longitudinal follow-up study from October 2015 to September 2016. Data on QoL at baseline and in 6 months were collected by trained nurses through face-to-face interviews using a short Amharic version of World Health Organization QoL instrument for HIV clients. Multiple linear regressions were used to assess the predictors of health-related QoL. There was an improvement in all of the domains of QoL at the sixth month follow-up compared with the baseline for both groups of patients (P < 0.001). Lack of social support and income were associated with the low improvement in QoL in most of the domains in both groups. Compared with patients having severe acute malnutrition, patients having moderate acute malnutrition and normal nutritional status were better in most of the QoL domains in both groups of patients. Both antiretroviral and anti-VL treatments showed improvement in all dimensions of QoL. Income, social support, and nutritional status were the predictors for most of the QoL domains.

To evaluate the dynamics of regulatory T cells (Tregs) during tegumentary leishmaniasis, we assessed peripheral blood and biopsies from 54 patients. Patients with cutaneous leishmaniasis (CL) had a decreased proportion of Tregs in the peripheral blood, but the proportion was higher in the biopsies of lesions. During treatment of CL, circulating Tregs increased reaching normal proportions, whereas antigen-specific interferon-γ responses diminished. By contrast, circulating Tregs from mucosal leishmaniasis patients failed to normalize during treatment. C-C chemokine receptor type 5 was expressed on a large proportion of Tregs at the site of infection. These results demonstrate increased Tregs at the site of infection, possibly homing from the peripheral circulation.