The American Journal of Tropical Medicine and Hygiene - Current Issue

As the global public health community develops strategies for sustainable Zika prevention and control, assessment of the Cuban response to Zika provides critical lessons learned. Cuba’s early and successful response to Zika, grounded in the country’s long-standing dengue prevention and control program, serves as a model of rapid mobilization of intersectoral efforts. Sustaining this response requires applying the evidence generated within the Cuban dengue program that active community participation improves outcomes and is sustainable and cost-effective. There is also a need for implementation science efforts to assess the transferability of lessons learned from Zika prevention and control to other pathogens and from one context to another in addition to how to take these efforts to scale.

Diphtheria is an acute disease caused by exotoxin-producing Corynebacterium diphtheriae. Globally, diphtheria has been showing a declining trend due to effective childhood vaccination programs. A substantial proportion of global burden of diphtheria is contributed by India. Hospital-based surveillance studies as well as diphtheria outbreaks published in last 20 years (1996–2016) indicate that diphtheria cases are frequent among school-going children and adolescents. In some Indian states, Muslim children are affected more. As per the national level health surveys, coverage of three doses of diphtheria vaccine was 80% during 2015–2016. Information about coverage of diphtheria boosters is not routinely collected through these surveys, but is expected to be low. Few studies also indicate low diphtheria immunity among school-going children and adults. The strategies for prevention of diphtheria need to focus on improving coverage of primary and booster doses of diphtheria vaccines administered as a part of Universal Immunization Program as well as introducing diphtheria vaccine for school-going children.

White-tailed deer (Odocoileus virginianus) are an abundant mammal with a wide geographic distribution in the United States, which make them good sentinels for monitoring arboviral activity across the country. Exposure to various arboviruses has been detected in white-tailed deer, typically in conjunction with another diagnostic finding. To better assess the exposure of white-tailed deer to seven arboviruses, we tested 1,508 sera collected from 2010 to 2016 for antibodies to eastern equine encephalitis (2.5%), Powassan (4.2%), St. Louis encephalitis, (3.7%), West Nile (6.0%), Maguari (19.4%), La Crosse (30.3%), and bluetongue (7.8%) viruses. At least one arbovirus was detected in 51.3%, and exposure to more than one arbovirus was identified in 17.6% of the white-tailed deer sampled.

Infectious disease surveillance is hindered by several factors, including limited infrastructure and geographic isolation of many resource-poor regions. In addition, the complexities of sample acquisition, processing, and analysis, even in developed regions, can be rate limiting. Therefore, new strategies to survey human populations for emerging pathogens are necessary. Xenosurveillance is a method that utilizes mosquitoes as sampling devices to search for genetic signatures of pathogens in vertebrates. Previously we demonstrated that xenosurveillance can detect viral RNA in both laboratory and field settings. However, its ability to detect bacteria and parasites remains to be assessed. Accordingly, we fed Anopheles gambiae mosquitoes blood that contained Trypanosoma brucei gambiense and Bacillus anthracis. In addition, we determined whether two additional emerging viruses, Middle East Respiratory Syndrome Coronavirus and Zika virus could be detected by this method. Pathogen-specific real-time reverse transcription polymerase chain reaction was used to evaluate the sensitivity of xenosurveillance across multiple pathogen taxa and over time. We detected RNA from all pathogens at clinically relevant concentrations from mosquitoes processed up to 1 day postbloodfeeding. These results demonstrate that xenosurveillance may be used as a tool to expand surveillance for viral, parasitic, and bacterial pathogens in resource-limited areas.

To evaluate the potential role of Aedes albopictus (Skuse) as a vector of Zika virus (ZIKV), colonized mosquitoes of low generation number (≤ F5) from Brazil, Houston, and the Rio Grande Valley of Texas engorged on viremic mice infected with ZIKV strains originating from Senegal, Cambodia, Mexico, Brazil, or Puerto Rico. Vector competence was established by monitoring infection, dissemination, and transmission potential after 3, 7, and 14 days of extrinsic incubation. Positive saliva samples were assayed for infectious titer. Although all three mosquito populations were susceptible to all ZIKV strains, rates of infection, dissemination, and transmission differed among mosquito and virus strains. Aedes albopictus from Salvador, Brazil, were the least efficient vectors, demonstrating susceptibility to infection to two American strains of ZIKV but failing to shed virus in saliva. Mosquitoes from the Rio Grande Valley were the most efficient vectors and were capable of shedding all three tested ZIKV strains into saliva after 14 days of extrinsic incubation. In particular, ZIKV strain DakAR 41525 (Senegal 1954) was significantly more efficient at dissemination and saliva deposition than the others tested in Rio Grande mosquitoes. Overall, our data indicate that, while Ae. albopictus is capable of transmitting ZIKV, its competence is potentially dependent on geographic origin of both the mosquito population and the viral strain.

Zika virus (ZIKV) has a wide clinical spectrum of associated neurologic disease including microcephaly and Guillain–Barre syndrome but, despite its known neurotropism, ZIKV meningoencephalitis and myelitis have been rare complications. We describe a case of ZIKV meningoencephalitis and probable myelitis and its associated magnetic resonance imaging findings that rapidly resolved during recovery in a previously healthy adult.

Human behaviors are increasingly recognized to play a key role in the spread of infectious diseases. Although a set of social and cognitive determinants has been consistently found to affect the adoption of health protective behaviors aiming to control and prevent a variety of infections, little is currently known about the ecological drivers of these behaviors in epidemic settings. In this article, we took advantage of the outbreak of chikungunya, a reemerging mosquito-borne disease, that occurred in French Guiana in 2014–15 to test empirically the assumption proposed by Zielinski-Gutierrez and Hayden that the proximity of the disease and perceptions of the natural environment may considerably shape public response to an emerging health threat. To achieve this, a cross-sectional survey was conducted among high school students of the region (N = 1462) at an early stage of the epidemic. Surprisingly, spatial analysis of the collected data leads to counterintuitive results as the participants who lived in the most affected area expressed less concern about the disease and practiced preventive behaviors less frequently than did other participants. These paradoxical results may be attributed to the possible activation of risk denial processes which have previously been observed in the risk perception literature, and described by several social and psychological defensiveness theories.

The Guillain–Barré syndrome (GBS) has been reported as a possible complication of acute chikungunya infection. The chikungunya epidemics, which occurred in Martinique and Guadeloupe in 2014, affected 308,000 people in these two islands. GBS occurred during or immediately after acute chikungunya infection in 13 patients (10 men, three women; mean age: 61 years). Median time from acute chikungunya to GBS onset was 9 days. Twelve patients were treated with intravenous polyvalent immunoglobulins, nine of whom improved within 7 days. Five of 13 patients required mechanical ventilation. Two patients with severe GBS died. At 6 months of follow-up, 7/13 achieved a good functional recovery with no or minor residual symptoms. A 2-fold increase in incidence was observed during the year of chikungunya outbreak. This study supports prior reports suggesting that GBS may be a complication of chikungunya.

People in southern Taiwan experienced two major dengue outbreaks in 2014 and 2015. The mortality and clinical features were very different between these 2 years. Dengue virus serotype 1 (DENV-1) caused epidemic outbreak in 2014 and DENV-2 was predominant in 2015. The characteristics of dengue hemorrhagic fever (DHF) cases in the 2 years was analyzed. We conducted a retrospective chart review to analyze the clinical and laboratory features of 206 adult patients with DHF in southern Taiwan in 2014 and 2015. The mortality rate of DHF cases in 2015 was higher than that of cases in 2014 (38.7% versus 12.4%, P < 0.0001). Compared with cases in 2014, DHF cases in 2015 had more complications, such as gastrointestinal bleeding (78.5% versus 61.9%, P = 0.01), severe hepatitis (30.1% versus 8%, P < 0.0001), and myocarditis (14% versus 0.9%, P < 0.0001). Among the mortality cases, diabetes, chronic renal failure, proton-pump inhibitors using, platelet transfusion, and Charlson comorbidity index score (Charlson score) were also higher in 2015. Multivariate analysis for the mortality cases revealed that the risk factors were Charlson score ≥ 5 (P = 0.02, odds ratio [OR] = 4.07, 95% confidence interval [CI] = 1.244–13.307), severe hepatitis (P < 0.0001, OR = 11.97, 95% CI = 3.831–37.396), and acute renal failure (P < 0.0001, OR = 98.76, 95% CI = 10.847–899.22). DHF cases in 2015 had higher mortality and more complications, such as gastrointestinal bleeding, severe hepatitis, and myocarditis, than in 2014 in southern Taiwan. In the 2-year DHF case series, Charlson score ≥ 5, severe hepatitis, and acute renal failure were independent significant variables for mortality.

Japanese encephalitis (JE) virus is a major cause of devastating viral encephalitis, especially in Asia. Although a successful vaccination program led to its near-elimination over three decades in South Korea, the incidence of JE has increased since 2010. The present study investigated the clinical manifestations, laboratory findings, and factors affecting neurological outcomes of reemerging JE. We retrospectively reviewed medical records of laboratory-confirmed JE patients who presented with acute encephalitis syndrome at three tertiary hospitals between 2010 and 2015. A total of 17 patients with JE were identified. Their median age was 51 years, and 10 (58.5%) were men. The most common symptoms and signs were fever (94.1%), altered consciousness (94.1%), and headache (80.2%). Hyporeflexia (47.1%), seizures (35.2%), abnormal brainstem reflex (23.5%), and flaccid weakness (17.6%) were also noted. Brain imaging revealed thalamic lesions in all patients, with the hippocampus, midbrain, basal ganglia, and cerebral cortex affected to varying degrees. Sixteen patients (94.1%) required management in the intensive care unit with mechanical ventilation due to neurological deterioration. At the time of discharge, 11 (64.7%) had poor recovery, defined as Glasgow coma scale scores of less than 8, and remained ventilator dependent. Comparison between the two outcome groups indicated that midbrain involvement (P = 0.028) and rapid deterioration (P = 0.005) were associated with severe neurological sequelae. Given that JE is a vaccine-preventable disease, vaccination for adults should be considered in response to the reemergence of JE.

Almost all human infections by avian influenza viruses (AIVs) are transmitted from poultry. A systematic review was conducted to identify practices associated with human infections, their prevalence, and rationale. Observational studies were identified through database searches. Meta-analysis produced combined odds ratio estimates. The prevalence of practices and rationales for their adoptions were reported. Of the 48,217 records initially identified, 65 articles were included. Direct and indirect exposures to poultry were associated with infection for all investigated viral subtypes and settings. For the most frequently reported practices, association with infection seemed stronger in markets than households, for sick and dead than healthy poultry, and for H7N9 than H5N1. Practices were often described in general terms and their frequency and intensity of contact were not provided. The prevalence of practices was highly variable across studies, and no studies comprehensively explored reasons behind the adoption of practices. Combining epidemiological and targeted anthropological studies would increase the spectrum and detail of practices that could be investigated and should aim to provide insights into the rationale(s) for their existence. A better understanding of these rationales may help to design more realistic and acceptable preventive public health measures and messages.

In highly endemic settings for hepatitis B virus (HBV) infection such as Senegal, access to HBV prevention and care is rapidly evolving. In this context, all medical practitioners should have baseline knowledge on HBV infection and promote access to vaccination, screening, and care. A knowledge and attitudes survey on HBV infection was conducted among a randomly selected sample of medical practitioners in Senegal. Participants were asked to fill-out a questionnaire on the HBV epidemiology, prevention, and treatment. A 60-item knowledge score was computed; the lower quartile of the observed score was used to define poor knowledge. Factors associated with poor knowledge were assessed using a logistic regression model. A total of 127 medical practitioners completed the questionnaire. Only 14 (11.0%) participants knew that HBV vaccine could be safely administered to pregnant women and 65 (51.2%) to newborns. Older practitioners (> 40 years) as well as general practitioners (compared with specialists) were more likely to have a poor knowledge score with odds ratios (ORs) of 3.1 (95% confidence interval [CI] 1.0–9.2) and 2.6 (95% CI 1.0–7.3), respectively. Practitioners who declared not to recommend HBV screening frequently during their consultation were more likely to present a poor knowledge score [OR: 3.0; (95% CI 1.1–8.2)]. As universal HBV screening is being promoted in countries with endemic HBV infection, our finding that poor screening attitudes were associated with a poor knowledge is of concern. There is a need to raise awareness of medical practitioners in Senegal toward universal HBV screening and early vaccination of newborns.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a novel phlebovirus that was identified to be the etiological pathogen of the emerging infectious disease, severe fever with thrombocytopenia syndrome (SFTS). SFTSV could be transmitted through tick bite. Transmission of SFTSV among humans has also been reported mainly through direct blood contact. In July 2014, a cluster of six suspected SFTS cases occurred in Shandong Province, China. In this cluster, both symptomatic and asymptomatic persons were included. By analyzing the clinical data and results of laboratory tests, and conducting the epidemiological interviews with the cases and their families, risk factors responsible for the transmission were evaluated. The findings suggested that SFTSV transmission among humans may cause asymptomatic infection via personal contact without blood exposure.

Human granulocytic anaplasmosis (HGA) is a tick-borne infectious disease caused by Anaplasma phagocytophilum, an obligate intracellular bacterium. Until now, the utility of tick-bite site samples for HGA diagnosis has not been reported. Using a patient's buffy coat and tick-bite site crust samples, we performed polymerase chain reaction (PCR) testing using Ehrlichia- or Anaplasma-specific primers. PCR with buffy coat and crust samples obtained before doxycycline administration was positive. Six days after doxycycline administration, PCR with the buffy coat sample was negative but PCR with a crust tissue sample from the tick-bite site remained positive. This is the first case to suggest that crust tissue at the tick-bite site may be useful for early HGA diagnosis in patients who have already been treated with antibiotics such as doxycycline.

It has been claimed that dogs can be useful sentinels for public health monitoring of vector-borne infectious diseases, including Rickettsia spp. We used 153 canine blood samples opportunistically collected at Murdoch University Veterinary Hospital and 156 canine sera collected from Aboriginal communities in northwest Western Australia to test for evidence of Rickettsia spp. exposure, using microimmunofluorescence (MIF) in the latter case, and both MIF and polymerase chain reaction (PCR) in the former. Conventional and real-time PCR failed to amplify any Rickettsia spp. DNA. The seroprevalence for spotted fever group/transitional group Rickettsia spp. in Western Australian dogs was 17.3% (54/312), and for typhus group (TG) Rickettsia spp., 18.4% (57/310), with a cut-off titer of 1:128. Young dogs (≤ 2 years) from Aboriginal communities had significantly lower seropositivity to TG Rickettsia spp. compared with all other groups, and young Perth dogs had a significantly higher seropositivity to TG Rickettsia spp. than all Aboriginal community dogs.

Although emerging nonviral pathogens remain relatively understudied in bat populations, there is an increasing focus on identifying bat-associated bartonellae around the world. Many novel Bartonella strains have been described from both bats and their arthropod ectoparasites, including Bartonella mayotimonensis, a zoonotic agent of human endocarditis. This cross-sectional study was designed to describe novel Bartonella strains isolated from bats sampled in Mexico and evaluate factors potentially associated with infection. A total of 238 bats belonging to seven genera were captured in five states of Central Mexico and the Yucatan Peninsula. Animals were screened by bacterial culture from whole blood and/or polymerase chain reaction of DNA extracted from heart tissue or blood. Bartonella spp. were isolated or detected in 54 (22.7%) bats, consisting of 41 (38%) hematophagous, 10 (16.4%) insectivorous, and three (4.3%) phytophagous individuals. This study also identified Balantiopteryx plicata as another possible bat reservoir of Bartonella. Univariate and multivariate logistic regression models suggested that Bartonella infection was positively associated with blood-feeding diet and ectoparasite burden. Phylogenetic analysis identified a number of genetic variants across hematophagous, phytophagous, and insectivorous bats that are unique from described bat-borne Bartonella species. However, these strains were closely related to those bartonellae previously identified in bat species from Latin America.

This is the first report of the molecular epidemiology of Staphylococcus aureus from skin and soft tissue infections (SSTI) in Laos. We selected a random sample of 96 S. aureus SSTI isolates received by the Microbiology Laboratory, Mahosot Hospital, Vientiane, between July 2012 and June 2014, including representation from seven referral hospitals. Isolates underwent susceptibility testing by Clinical and Laboratory Standards Institute methods, spa typing and DNA microarray analysis, with whole genome sequencing for rare lineages. Median patient age was 19.5 years (interquartile range 2–48.5 years); 52% (50) were female. Forty-three spa types, representing 17 lineages, were identified. Fifty-eight percent (56) of all isolates encoded Panton-Valentine leukocidin (PVL), representing six lineages: half of these patients had abscesses and three had positive blood cultures. The dominant lineage was CC121 (39; 41%); all but one isolate encoded PVL and 49% (19) were from children under five. Staphyococcus argenteus was identified in six (6%) patients; mostly adults > 50 years and with diabetes. Six isolates (6%) belonged to rare lineage ST2885; two possibly indicate cross-infection in a neonatal unit. One isolate from a previously undescribed lineage, ST1541, was identified. Antibiotic resistance was uncommon except for penicillin (93; 97%) and tetracycline (48; 50%). Seven (7%) isolates were methicillin-resistant S. aureus (MRSA), belonging to ST239-MRSA-III, CC59-MRSA-V(T) Taiwan Clone, ST2250-MRSA-IV, ST2885-MRSA-V and CC398-MRSA-V. Globally widespread CC5 and CC30 were absent. There are parallels in S. aureus molecular epidemiology between Laos and neighboring countries and these data highlight the prominence of PVL and suggest infiltration of MRSA clones of epidemic potential from surrounding countries.

Tobacco use is a major risk factor for tuberculosis (TB). Secondhand smoke (SHS) is also a risk factor for TB and to a lesser extent, Mycobacterium tuberculosis infection without disease. We investigated the added risk of M. tuberculosis infection due to SHS exposure in childhood contacts of TB cases in The Gambia. Participants were childhood household contacts aged ≤ 14 years of newly diagnosed pulmonary TB (PTB) cases. The intensity of exposure to the case was categorized according to whether contacts slept in the same room, same house, or a different house as the case. Contacts were tested with an enzyme-linked immunospot interferon gamma release assay. In multivariate regression models, M. tuberculosis infection was associated with increasing exposure to a case (odds ratios [OR]: 3.9, 95% confidence interval [CI]: 2.11–71.4, P < 0.001]) and with male gender (OR: 1.5 [95% CI: 1.12–2.11], P = 0.008). Tobacco use caused a 3-fold increase in the odds of M. tuberculosis infection in children who slept closest to a case who smoked within the same home compared with a nonsmoking case (OR: 8.0 [95% CI: 2.74–23.29] versus 2.4 [95% CI: 1.17–4.92], P < 0.001). SHS exposure as an effect modifier appears to greatly increase the risk of M. tuberculosis infection in children exposed to PTB cases. Smoking cessation campaigns may be important for reducing transmission of M. tuberculosis to children within households.