The American Journal of Tropical Medicine and Hygiene - Volume 96, Issue 4, 2017

Infectious disease continues to adversely affect populations in low- and middle-income countries. Investments in solutions often focus on technology, yet health-care workers remain in short supply. Nurses are the largest cadre of health-care workers and are largely responsible for patient care around the world. In fact, it is estimated that nurses care for nine out of every 10 patients seen. Importantly, sound nursing science contributes to solutions that directly impact patient care, especially those that pertain to infectious disease. Here we share several examples of nursing science that are improving care delivery in three global health areas: human immunodeficiency virus testing and prevention strategies in Malawi, family planning in Kenya, and response to Ebola virus disease.

The process of globalization is commonly espoused as a means for promoting global health. Efforts to “go global” can, however, easily go awry as a result of lack of attention to local social, economic, and political contexts and/or as a result of commercial and political imperatives that allow local populations to be exploited. Critical analysis of the processes of globalization is necessary to better understand the local particularities of global projects and confront challenges more transparently. We illustrate the potential adverse impacts of globalization in the global health setting, through examination of international tuberculosis control, global mental health, and the establishment of transnational biobank networks.

Pregnant women and their developing fetuses are vulnerable to multiple environmental insults, including exposure to aflatoxin, a mycotoxin that may contaminate as much as 25% of the world food supply. We reviewed and integrated findings from studies of aflatoxin exposure during pregnancy and evaluated potential links to adverse pregnancy outcomes. We identified 27 studies (10 human cross-sectional studies and 17 animal studies) assessing the relationship between aflatoxin exposure and adverse birth outcomes or anemia. Findings suggest that aflatoxin exposure during pregnancy may impair fetal growth. Only one human study investigated aflatoxin exposure and prematurity, and no studies investigated its relationship with pregnancy loss, but animal studies suggest aflatoxin exposure may increase risk for prematurity and pregnancy loss. The fetus could be affected by maternal aflatoxin exposure through direct toxicity as well as indirect toxicity, via maternal systemic inflammation, impaired placental growth, or elevation of placental cytokines. The cytotoxic and systemic effects of aflatoxin could plausibly mediate maternal anemia, intrauterine growth restriction, fetal loss, and preterm birth. Given the widespread exposure to this toxin in developing countries, longitudinal studies in pregnant women are needed to provide stronger evidence for the role of aflatoxin in adverse pregnancy outcomes, and to explore biological mechanisms. Potential pathways for intervention to reduce aflatoxin exposure are urgently needed, and this might reduce the global burden of stillbirth, preterm birth, and low birthweight.

Human granulocytic anaplasmosis (HGA) is a tick-borne rickettsial zoonosis with fever, thrombocytopenia, and leukopenia. HGA has been reported in Korea in 2013 but it is uncertain how long it has existed. A retrospective study was conducted on patients who underwent bone marrow examination due to fever and cytopenia, with no clear hematologic or microbiologic causes, from 2003 through 2012. Laboratory diagnosis was made by detecting 16S rRNA genes of Anaplasma phagocytophilum from the stored blood samples. Among the 70 patients, five (7.1%) HGA cases were found, and the earliest case dated back to 2006. Two cases met the diagnostic criteria of hemophagocytic lymphohistiocytosis (HLH) and were fatal. Although HGA has been prevalent in Korea since at least 2006, it is not always diagnosed and has posed a possible lethal health risk to the people in Korea. HGA should be considered as a cause of fever with cytopenia or HLH.

Rickettsial infections are an underrecognized cause of febrile illness in sub-Saharan Africa. To evaluate the epidemiology and clinical features of rickettsial disease in pediatric patients in Ghana, we screened blood samples from febrile children aged less than 15 years presenting to an outpatient department in Ghana's Ashanti Region for the presence of rickettsial DNA. We detected Rickettsia felis in 7/470 (1.5%) blood samples, using two independent real-time polymerase chain reactions. No other Rickettsia species were found. R. felis was detected repeatedly in one patient, and coinfection with Plasmodium falciparum was found in 3/7 samples. Symptoms apart from fever included cough (6/7) and vomiting (4/7). None of the R. felis-positive patients reported a rash. This study is the first report on R. felis in Ghana and adds to the growing evidence for its widespread occurrence with and without malaria coinfection in sub-Saharan Africa.

Little is known about the burden of Q fever in Thailand. We conducted a serological study to describe the prevalence of anti-Coxiella burnetii antibodies among ruminants and occupationally exposed persons in response to the report of the first two Q fever endocarditis patients in Thailand in 2012. We randomly selected ruminant sera from brucellosis surveillance and examined sera of 661 occupationally exposed subjects from two provinces of Thailand: Chiangmai and Nakornratchasima. Animal and human sera were tested using commercial enzyme-linked immunosorbent assay (ELISA). Environmental samples, vaginal swab, and milk from cows in Chiangmai farms with detectable anti-C. burnetii serum antibodies were tested using polymerase chain reaction (PCR). Among the 1,632 animal sera tested, 64 (3.9%) were seropositive. The prevalence was highest in dairy cattle (4.6%, 45/988), followed by goats (3.5%, 18/516) and sheep (2.1%, 1/48). The prevalence of anti-C. burnetii antibodies in each species varied significantly by province: the prevalence in cattle was higher in Chiangmai (5.5% versus 0%), however, the prevalence in sheep and goats was higher in Nakornratchasima (5.9% versus 1.0%). Four out of 60 milk samples were positive by PCR (6.7%). No environmental samples were positive. Among 661 human samples, 83 (12.6%) were ELISA positive. Seroprevalence was statistically higher in Chiangmai compare with Nakornratchasima (42.8% versus 3.0%). Coxiella burnetii infection exists in Thailand, but the prevalence varies by geographic distribution and animal reservoirs. Further studies focusing on the burden and risk factors of C. burnetii infection among high-risk groups should be conducted.

A Jarisch–Herxheimer reaction (JHR) may be precipitated after initiation of chemotherapy in spirochetal diseases, including leptospirosis. However, a clear idea of the importance of JHR in this disease is lacking. The incidence of and risk factors for JHR were investigated retrospectively among 262 patients with confirmed leptospirosis who received amoxicillin treatment in New Caledonia and Futuna. The overall rate of JHR was 21% (12% in New Caledonia and 44% in Futuna). Two risk factors were independently associated with JHR occurrence: Leptospira interrogans serogroup Australis as the infecting strain (odds ratio [OR] = 2.60, confidence interval [CI] = 1.40–5.62) and delays < 3 days between the onset of symptoms and the initiation of antibiotherapy (OR = 2.14, CI = 1.11–4.38). Clinicians should be aware of JHR as a potential complication of leptospirosis. Strain-related factors associated with JHR occurrence and its impact on outcome remains to be explored.

Staphylococcus aureus is an important cause of morbidity and mortality in children in sub-Saharan Africa (SSA). A major risk factor for staphylococcal infection is S. aureus colonization of the anterior nares. We sought to define risk factors for S. aureus carriage and characterize antimicrobial resistance patterns in children in Botswana. A cross-sectional study was conducted at two clinical sites in southern Botswana. Patients under 18 years of age underwent two nasal swabs and brief interviews, 4 weeks apart. Standard microbiological techniques were used. For persistent carriers, S. aureus was isolated from swabs at both time points, and for intermittent carriers, S. aureus was isolated from only one swab. Poisson regression with robust variance estimator was used to compare prevalence of carriage and the resistance phenotypes. Among 56 enrollees, prevalence of S. aureus colonization was 55% (N = 31), of whom 42% (N = 13) were persistent carriers. Of human immunodeficiency virus–infected children, 64% (N = 9) were carriers. Risk factors for nasal carriage included a history of tuberculosis (prevalence ratio [PR] = 1.60; 95% confidence interval [CI] = 1.02, 2.51; P = 0.040) and closer proximity to health care (PR = 0.89; 95% CI = 0.80, 0.99; P = 0.048). Prior pneumonia was more common among persistent rather than intermittent carriers (PR = 2.64; 95% CI = 1.64, 4.23; P < 0.001). Methicillin-resistant S. aureus (MRSA) prevalence was 13%. Of isolates tested, 16% were resistant to three or more drugs (N = 7/44). In summary, children in southern Botswana are frequently colonized with S. aureus. Antibiotic resistance, especially MRSA, is also widespread. Antibiotic recommendations for treatment of staphylococcal infections in SSA should take cognizance of these resistance patterns.

Visceral leishmaniasis (VL), popularly known as kala-azar, is essentially a disease of poverty. Kala-azar is caused by a parasite, Leishmania donovani. Recent review indicates that worldwide 98 countries are endemic for kala-azar. Approximately 0.2–0.4 million new VL cases occur each year worldwide. More than 90% of global VL cases occur in Bangladesh, Brazil, Ethiopia, India, South Sudan, and Sudan. This trend is slowly changing due to the progress in kala-azar elimination in southeast Asia, where Bangladesh has reported an average of some 600 new cases in 2014−2015. With the advancement in our knowledge about the disease and development of tools to diagnose and treat VL, it was considered that elimination of kala-azar was possible from India, Nepal, and Bangladesh. The three countries signed a memorandum of understanding in 2005 for collaboration. Miltefosine is the first ever oral drug developed to treat VL, which was later replaced by lipid amphotericin B. The main components of the strategy are early diagnosis using rK39 strip test and complete treatment utilizing miltefosine for 28 days. Dichlorodiphenyltrichloroethane or pyrethroids were deployed for vector control. There was much to be desired for better performance of the vector control activity. Pharmacovigilance and monitoring of drug resistance were the weakest part of the program. In the post-elimination phase, surveillance reinforced by active case finding will of a crucial factor for sustainability of the elimination. A strong political will is required to ensure elimination of kala-azar from the Indian subcontinent and its sustainability in the post-elimination phase.

The zoonotic, vector-borne parasite Trypanosoma cruzi causes Chagas disease throughout the Americas, but human and veterinary health burdens in the United States are unknown. We conducted a cross-sectional prevalence study in indigent, medically underserved human and cohabiting canine populations of seven south Texas border communities, known as colonias. Defining positivity as those samples that were positive on two or more independent tests, we found 1.3% seroprevalence in 233 humans, including one child born in the United States with only short-duration travel to Mexico. Additionally, a single child with no travel outside south Texas was positive on only a single test. Among 209 dogs, seroprevalence was 19.6%, but adjusted to 31.6% when including those dogs positive on only one test and extrapolating potential false negatives. Parasite DNA was detected in five dogs, indicating potential parasitemia. Seropositive dogs lived in all sampled colonias with no difference in odds of positivity across age, sex, or breed. Colonia residents collected two adult Triatoma gerstaeckeri and one nymph triatomine from around their homes; one of three bugs was infected with T. cruzi, and blood meal hosts were molecularly determined to include dog, human, and raccoon. Dogs and the infected vector all harbored T. cruzi discrete typing unit I, which has previously been implicated in human disease in the United States. Colonias harbor active T. cruzi transmission cycles and should be a priority in outreach and vector control initiatives.

Characterization of the parasite reservoir is required to improve malaria control. Asymptomatic patients with subpatent parasitemia have been identified in Gabon, but the prevalence of such infections among febrile subjects is unclear. We assessed the prevalence of submicroscopic Plasmodium falciparum infections on an island (Port-Gentil), and in urban (Libreville), semiurban (Melen), and rural (Oyem) settings in Gabon. Blood samples (N = 310) from febrile patients were tested for malaria parasites by quantitative nucleic acid sequence–based amplification (QT-NASBA). Parasites were detected in 55.8% (173/310) of samples by microscopy and in 66.4% (206/310) of samples by 18S rRNA QT-NASBA. The proportion of submicroscopic infections differed considerably between sites. Gametocytes were found in 1% (3/310) of the individuals by microscopy and in 32% (99/310) by Pfs25 mRNA QT-NASBA. Thus, submicroscopic parasitemia is frequent in febrile patients, and the detection of this condition is important, to improve disease control.

The Department of Santa Rosa, Guatemala, is targeted for malaria elimination. However, compared with 2011, a 13-fold increase in cases was reported in 2012. To describe the epidemiology of malaria in Santa Rosa in the setting of the apparent outbreak, demographic and microscopic data from 2008 to 2013 were analyzed. In April 2012, a new surveillance strategy, funded by the Global Fund to Fight AIDS, Tuberculosis and Malaria, was introduced involving more active case detection, centralized microscopy, increased community engagement, and expanded vector control. Interviews with vector control personnel and site visits were conducted in June 2013. From 2008 to 2013, 337 cases of malaria were reported. The increase in cases occurred largely after the new surveillance strategy was implemented. Most (137/165; 83%) 2012 cases came from one town near a lake. Plasmodium vivax was the malaria species detected in all cases. Cases were detected where malaria was not previously reported. Monthly rainfall or/and temperature did not correlate with cases. Interviews with public health personnel suggested that the new funding, staffing, and strategy were responsible for improved quality of malaria detection and control and thus the increase in reported cases. Improvements in surveillance, case detection, and funding appear responsible for the temporary increase in cases, which thus may paradoxically indicate progress toward elimination.

Vitamin A and zinc are important for immune function and may improve host defense against malaria and reduce the risk of adverse pregnancy outcomes. Our objective was to determine whether daily oral supplementation with either or both nutrients starting in the first trimester reduces the risk of placental malaria and adverse pregnancy outcomes. We undertook a randomized, double-blind placebo-controlled trial with a factorial design among 2,500 human immunodeficiency virus–negative primigravid or secundigravid pregnant women in their first trimester of pregnancy in Dar es Salaam, Tanzania. We randomly allocated equal numbers of participants to 2,500 IU of vitamin A, 25 mg of zinc, both 2,500 IU of vitamin A and 25 mg of zinc, or a placebo until delivery. A total of 625 participants were allocated to each treatment group. Our primary outcome, placental malaria infection (past or current), was assessed in all randomized participants for whom placental samples were obtained at delivery (N = 1,404), which represents 56% of total participants and 62% of all pregnancies lasting 28 weeks or longer (N = 2,266). Birth outcomes were obtained for 2,434 of the 2,500 randomized participants. Secondary outcomes included small for gestational age (SGA) births and prematurity. All analyses were intent to treat. Those who received zinc had a lower risk of histopathology-positive placental malaria compared with those who did not receive zinc (risk ratio = 0.64, 95% confidence interval = 0.44, 0.91), but neither nutrient had an effect on polymerase chain reaction–positive malaria, SGA, or prematurity. No safety concerns were identified. We recommend additional studies in other geographic locations to confirm these findings.

Inbred mice are commonly used to test candidate malaria vaccines, but have been unreliable for predicting efficacy in humans. To establish a more rigorous animal model, we acquired African woodland thicket rats of the genus Grammomys, the natural hosts for Plasmodium berghei. Thicket rats were acquired and identified as Grammomys surdaster by skull and teeth measurements and mitochondrial DNA genotyping. Herein, we demonstrate that thicket rats are highly susceptible to infection by P. berghei, and moderately susceptible to Plasmodium yoelii and Plasmodium chabaudi: 1–2 infected mosquito bites or 25–100 sporozoites administered by intravenous injection consistently resulted in patent parasitemia with P. berghei, and resulted in patent parasitemia with P. yoelii and P. chabaudi strains for at least 50% of animals. We then assessed efficacy of whole-organism vaccines to induce sterile immunity, and compared the thicket rat model to conventional mouse models. Using P. berghei ANKA radiation-attenuated sporozoites, and P. berghei ANKA and P. yoelii chemoprophylaxis vaccination approaches, we found that standard doses of vaccine sufficient to protect laboratory mice for a long duration against malaria challenge, are insufficient to protect thicket rats, which require higher doses of vaccine to achieve even short-term sterile immunity. Thicket rats may offer a more stringent and pertinent model for evaluating whole-organism vaccines.

Schistosoma mansoni is a major public health threat in many parts of the world. The current diagnostic tests for schistosomiasis are suboptimal, particularly early in infection, when the parasite burden is low and with reinfection after treatment. We sought to identify novel biomarkers of active infection by studying serum proteins in a mouse model of schistosomiasis followed by confirmation in chronically infected patients. Acute (6 weeks) and chronic (12 weeks) sera from S. mansoni–infected C57Bl/6 mice as well as sera from chronically infected patients were assessed using two proteomic platforms: surface-enhanced, laser desorption and ionization, time-of-flight mass spectrometry and Velos Orbitrap mass spectrometry. Several candidate biomarkers were further evaluated by Western blot and/or enzyme-linked immunosorbent assay (ELISA). Among the most promising was carbonic anhydrase 1 (CA1), a host protein found primarily in red blood cells and enterocytes that proved to be a negative biomarker for schistosomiasis in both mouse and human samples. Reduced serum CA-1 levels were confirmed by both Western blot (murine and human: both P < 0.001) and ELISA (human: P < 0.01). Western blots of serial mouse sera revealed a progressive reduction in serum CA1 levels over the 12-week infection period. CA1 is a promising negative serum biomarker for the diagnosis of S. mansoni infection.

Schistosoma haematobium infection causes urogenital schistosomiasis, a chronic inflammatory disease that is highly prevalent in many parts of sub-Saharan Africa. Bulinid snails are the obligate intermediate hosts in the transmission of this parasite. In the present study, Bulinus globosus and Bulinus nasutus snails from coastal Kenya were raised in the laboratory and exposed to miracidia derived from sympatric S. haematobium specimens to assess the species-specific impact of parasite contact and infection. The snails' subsequent patterns of survival, cercarial shedding, and reproduction were monitored for up to 3 months postexposure. Schistosoma haematobium exposure significantly decreased the survival of B. globosus, but not of B. nasutus. Although both species were capable of transmitting S. haematobium, the B. globosus study population had a greater cumulative incidence of cercarial shedders and a higher average number of cercariae shed per snail than did the B. nasutus population. The effects of prior parasite exposure on snail reproduction were different between the two species. These included more numerous production of egg masses by exposed B. nasutus (as compared with unexposed snails), contrasted to decreased overall egg mass production by parasite-exposed B. globosus. The interspecies differences in the response to and transmission of S. haematobium reflect clear differences in life histories for the two bulinid species when they interact with the parasite, which should be taken into account when planning control interventions aimed at reducing each host snails' contribution to local transmission of Schistosoma infection.

Schistosomiasis is a parasitic worm infection that affects over 260 million individuals worldwide. Women with schistosome infections have been demonstrated to have a 4-fold increase in the odds of human immunodeficiency virus (HIV) infection compared with women without schistosome infections. A relationship between schistosome and HIV infections has not been clearly defined in men. Among 674 men aged 18–50 years living in rural Tanzania, we identified 429 (63.6%) who had a schistosome infection as defined by serum positivity for schistosome circulating anodic antigen, visualization of parasite eggs in urine or stool, or both. HIV infection was identified in 38 (5.6%). The odds of HIV infection was 1.3 [95% confidence interval = 0.6–2.5] (P = 0.53) among men with any schistosome infection (Schistosoma haematobium or Schistosoma mansoni), and it was 1.4 [0.6–3.3] (P = 0.43) among men with S. haematobium infection. Men with S. haematobium infection were significantly more likely to report the symptom of hemospermia than men without S. haematobium infection. We conclude that schistosome infections appear to have little to no association with HIV infection in men.

A modification of Koga agar plate culture was performed, consisting of a 2 × 2-cm cellophane paper centered on the agar plate to prevent bacterial contamination of the agar and daily dish examinations (days 2–5). Between January 2000 and July 2005, we examined 1,708 infection-suspected patients, of which 147 (8.6%) harbored S. stercoralis. Single modified agar plate cultures exhibited superior sensitivity (93.2%), compared with different three-sample screening methods (sensitivity—Baermann: 76.6%, formalin-ethyl acetate: 22%, and direct smear: 15.3%). Agar plate cultures stand out as helpful alternatives for improved detection and therapy monitoring in poor countries and endemic areas. Combined with Baermann methods, they provide increased probability for S. stercoralis detection.

Intestinal parasites are important contributors to global morbidity and mortality and are the second most common cause of outpatient morbidity in Ethiopia. This cross-sectional survey describes the prevalence of soil-transmitted helminths and intestinal protozoa in preschool children 0–5 years of age in seven communities in the Amhara region of Ethiopia, and investigates associations between infection, household water and sanitation characteristics, and child growth. Stool samples were collected from children 0–5 years of age, 1 g of sample was preserved in sodium acetate–acetic acid–formalin, and examined for intestinal helminth eggs and protozoa cysts ether-concentration method. A total of 212 samples were collected from 255 randomly selected children. The prevalence of Ascaris lumbricoides, Trichuris trichiura, and hookworm were 10.8% (95% confidence interval [CI] 6.6–15.1), 1.4% (95% CI = 0–3.0), and 0% (95% CI = 0–1.7), respectively. The prevalence of the pathogenic intestinal protozoa Giardia lamblia and Entamoeba histolytica/dispar were 10.4% (95% CI = 6.2–14.6) and 3.3% (95% CI = 0.09–5.7), respectively. Children with A. lumbricoides infections had lower height-for-age z-scores compared with those without, but were not more likely to have stunting. Compared with those without G. lamblia, children with G. lamblia infections had lower weight-for-age and weight-for-height z-scores and were more than five times as likely to meet the z-score definition for wasting (prevalence ratio = 5.42, 95% CI = 2.97–9.89). This article adds to a growing body of research on child growth and intestinal parasitic infections and has implications for their treatment and prevention in preschool-aged children.