Malaria Rapid Diagnostic Tests: Literary Review and Recommendation for a Quality Assurance, Quality Control Algorithm.

Malaria rapid diagnostic tests (RDTs) have had an enormous global impact which contributed to the World Health Organization paradigm shift from empiric treatment to obtaining a parasitological diagnosis prior to treatment. Microscopy, the classic standard, requires significant expertise, equipment, electricity, and reagents. Alternatively, RDT's lower complexity allows utilization in austere environments while achieving similar sensitivities and specificities. Worldwide, there are over 200 different RDT brands that utilize three antigens: Plasmodium histidine-rich protein 2 (PfHRP-2), Plasmodium lactate dehydrogenase (pLDH), and Plasmodium aldolase (pALDO). pfHRP-2 is produced exclusively by Plasmodium falciparum and is very Pf sensitive, but an alternative antigen or antigen combination is required for regions like Asia with significant Plasmodium vivax prevalence. RDT sensitivity also decreases with low parasitemia (<100 parasites/uL), genetic variability, and prozone effect. Thus, proper RDT selection and understanding of test limitations are essential. The Center for Disease Control recommends confirming RDT results by microscopy, but this is challenging, due to the utilization of clinical laboratory standards, like the College of American Pathologists (CAP) and the Clinical Lab Improvement Act (CLIA), and limited recourses. Our focus is to provide quality assurance and quality control strategies for resource-constrained environments and provide education on RDT limitations.

HIV-1 Infection Is Associated With Increased Prevalence and Abundance of Plasmodium falciparum Gametocyte-Specific Transcripts in Asymptomatic Adults in Western Kenya.

As morbidity and mortality due to malaria continue to decline, the identification of individuals with a high likelihood of transmitting malaria is needed to further reduce the prevalence of malaria. In areas of holoendemic malaria transmission, asymptomatically infected adults may be infected with transmissible gametocytes. The impact of HIV-1 on gametocyte carriage is unknown, but co-infection may lead to an increase in gametocytemia. In this study, a panel of qPCR assays was used to quantify gametocyte stage-specific transcripts present in dried blood spots obtained from asymptomatic adults seeking voluntary HIV testing in Kombewa, Kenya. A total of 1,116 Plasmodium-specific 18S-positive samples were tested and 20.5% of these individuals had detectable gametocyte-specific transcripts. Individuals also infected with HIV-1 were 1.82 times more likely to be gametocyte positive (P<0.0001) and had significantly higher gametocyte copy numbers when compared to HIV-negative individuals. Additionally, HIV-1 positivity was associated with higher gametocyte prevalence in men and increased gametocyte carriage with age. Overall, these data suggest that HIV-positive individuals may have an increased risk of transmitting malaria parasites in regions with endemic malaria transmission and therefore should be at a higher priority for treatment with gametocidal antimalarial drugs.

A cross-sectional analysis of clinical presentations of and risk factors for enteric protozoan Infections in an Active Duty Population during Operation Iraqi Freedom.

BACKGROUND: Infectious travelers' diarrhea (TD) is a well-appreciated problem among service members serving abroad, particularly where infrastructure is limited due to ongoing combat operations, and efforts at sanitation and hygiene may not be considered an immediate priority. Bacterial and viral causes of travelers' diarrhea are well-described among deployed service members, however, gastrointestinal protozoan infections among deployed service members are less well documented. This study's purpose was to identify potential risk factors for, and clinical presentations of, enteric protozoan infections in an active duty military population deployed to combat operations in the Southwest Asia. METHODS: A cross-sectional study of enteric protozoan infections among US service members deployed in Al-Asad Air Base, Iraq in support of Operation Iraqi Freedom (OIF) was conducted in summer 2004. Subjects were obtained through a randomized sector sampling scheme, and through presentations for care at the air base medical facilities. All study participants provided a stool sample, either diarrhea or solid, upon study entry and completed a questionnaire documenting demographic information, clinical symptoms of any prior diarrheal episodes, and health risk behaviors. Basic diagnostic microscopy for protozoa was conducted to include acid-fast and modified trichrome staining. RESULTS: Four hundred thirty-seven subjects were included in the analysis, and 75 (17.1 %) subjects were found to have enteric protozoan infections as identified by diagnostic stool microscopy. Blastocystis hominis (n = 36), Entamoeba coli (n = 25), Endolimax nana (n = 20), and Entamoeba histolytica (n = 5) were the predominant organisms isolated. Crude incidence of prior episodes of diarrhea was greater among subjects from whom enteric protozoa were isolated compared to those without (IRR 1.66, 95 % CI 1.47-1.87). Bivariate analysis of health risk and hygiene behaviors found increased odds for presence of Blastocystis hominis among those service members who reported off base ice (OR 3.61, 95 % CI 1.40-9.28) and raw vegetable consumption (OR 8.18, 95 % CI 1.40-47.5). CONCLUSIONS: This study suggests that US service members deployed to the early stages of OIF were at greater risk of acquiring enteric protozoa than previously understood. The noted prevalence of enteric protozoa among US service members in this study is higher than in prior reports, approaching prevalence expected in the general host nation population, suggesting that US service members operating at Al-Asad Air Base in early OIF were exposed to greater degrees of fecally contaminated food and water, and poor hygienic and sanitation practices. Consumption of food and water prepared by host nation parties in Southwest Asia may place US service members at risk for acquiring intestinal protozoa.

A prospective study of acute diarrhea in a cohort of United States military personnel on deployment to the Multinational Force and Observers, Sinai, Egypt.

To better understand the epidemiology of diarrhea in deployed personnel to the Middle East, a prospective cohort study of travelers' diarrhea (TD) was conducted between May 2004 and January 2005 at the Multinational Force and Observers (MFO) camp in the southern Sinai. A baseline entry questionnaire and stool specimen was provided on study entry, and volunteers were followed every 6 weeks. Of 211 volunteers, 145 (68.7%) completed one or more follow-up visits. In total, 416 follow-up surveys were completed, which described an overall incidence of 25.2 episodes per 100 person months (95% confidence interval = 21.2-30.0). Additionally, stools were collected in 72 of 77 diarrhea-associated clinic visits, with bacterial pathogens most commonly isolated (enterotoxigenic Escherichia coli in 30 [42%] samples and Campylobacter jejuni in 7 [10%] samples) Despite modern preventive methods, diarrhea is still a common problem for deployed US military personnel in Egypt, frequently resulting in diminished ability to work.

Detection of gyrA mutation among clinical isolates of Campylobacter jejuni isolated in Egypt by MAMA-PCR.

INTRODUCTION: Campylobacter spp are the major cause of enteritis in humans and more than 90% of reported infections are caused by Campylobacter jejuni. Fluoroquinolones such as ciprofloxacin are the antibiotics of choice for treatment. An increase in the frequency of ciprofloxacin-resistant Campylobacter has been reported globally due to a single base mutation (C-257 to T) in codon 86 of the quinolone resistance determining region (QRDR) of the gyrA gene altering the amino acid sequence from threonine at position 86 to isoleucine (Thr-86 to Ile). METHODOLOGY: Campylobacter spp (n = 118) were selected from a collection of Egyptian isolates spanning 1998 to 2005. The presence of C. jejuni gyrA gene was confirmed in each isolate by a PCR assay amplifying 368 bp portion of the gyrA gene. C to T alteration was detected by the mismatch amplification mutation assay MAMA PCR. The MIC of nalidixic acid (NA) and ciprofloxacin (CIP) was determined by E-test. RESULTS: C. jejuni gyrA gene was detected in 100 of the Campylobacter spp studied; the other 18 isolates were found to be Campylobacter coli by lpxA PCR. The mutation was detected in 89 C. jejuni resistant isolates with MIC values (NA; 8 - >256 µg/ml) and (CIP; 4 - >32 µg/ml). The other 11 sensitive C. jejuni isolates with MIC values (NA; 0.38 - 3 µg/ml) and (CIP; 0.03 - 0.125 µg/ml) were not amplified by the MAMA primers. There was 100% congruence with MAMA PCR, MIC results and gyrA gene sequence analysis. CONCLUSIONS: In Egypt the main mechanism for resistance to fluoroquinolones is an alteration in the gyrA QRDR. MAMA PCR provides an economical and rapid means for screening fluoroquinolone resistance.

The epidemiology of travelers' diarrhea in Incirlik, Turkey: a region with a predominance of heat-stabile toxin producing enterotoxigenic Escherichia coli.

This study evaluated travelers' diarrhea among US military personnel on short-term deployment to Incirlik Air Base, Turkey, from June through September 2002. Upon reporting for care for travelers' diarrhea, subjects were enrolled into the study and completed a series of questionnaires and provided stool specimens for pathogen identification and antimicrobial susceptibility testing. Fifty-three percent of the 202 participating subjects had a pathogen isolated from their stool. Enterotoxigenic Escherichia coli (ETEC) was the predominant pathogen (41%), followed by Campylobacter spp. (12%). The most common ETEC phenotype recovered was stable toxin (ST) CS6 (47% of all ETEC). Most (91.1%) of the cases presented with water diarrhea regardless of isolated pathogen. However, there were some differences in nongastrointestinal symptoms among subjects with Campylobacter spp. All illnesses were well managed with antibiotics with or without loperamide with a median time to the last unformed stool of 9 h (interquartile range, 1-32 h). We found no food or environmental factors associated with a differential risk of infection with a specific pathogen. Travelers' diarrhea among a US military population in and around Incirlik, Turkey, can commonly be attributed to ETEC and Campylobacter spp. The high proportion of ST-only-producing CS6 ETEC in this region highlights the pathogen's worldwide diversity. Future studies of travelers' diarrhea in this population should adapt more novel microbiologic techniques such as polymerase chain reaction and enhanced culture methods to increase the likelihood of identifying pathogenic E. coli.

Azithromycin and loperamide are comparable to levofloxacin and loperamide for the treatment of traveler's diarrhea in United States military personnel in Turkey.

BACKGROUND: The recommended treatment for traveler's diarrhea is the combination of an appropriate antibiotic (usually a fluoroquinolone) and loperamide. Azithromycin compared favorably with fluoroquinolones in trials that did not include the use of loperamide, but combination therapy has not, to our knowledge, been studied to date. METHODS: A randomized, double-blind trial was conducted at Incirlik Air Base, Turkey, fromJ une 2003 through August 2004. Adults from the United States with noninflammatory diarrhea were randomized to receive a single dose of azithromycin (1000 mg; 106 persons) or levofloxacin (500 mg; 101 persons) plus loperamide (4 mg initially and as needed thereafter). Volunteers maintained a symptom diary and were evaluated on days 1, 3, and 7 after treatment. RESULTS: No differences were noted with respect to pretreatment symptoms or pathogen distribution. Enterotoxigenic Escherichia coli was the most common pathogen isolated (from 45% of patients in the azithromycin group and 42% of patients in the levofloxacin group), and Campylobacter species was the second most common pathogen isolated (from 6% of patients in the azithromycin group and 9% of patients in the levofloxacin group). Median time to last diarrheal stool (azithromycin group, 13 h; levofloxacin group, 3 h), median time to resolution of associated symptoms (2 days), and additional loperamide usage (azithromycin group, 39% of patients; levofloxacin group, 34% of patients) were similar between groups. Azithromycin use was associated with more nausea in the 30 min after dosing (azithromycin group, 8% of patients; levofloxacin group, 1% of patients; Pp.004), but no vomiting or other adverse events were noted in either group. CONCLUSIONS: Single-dose treatment with azithromycin (1000 mg) and loperamide is as effective as single-dose treatment with levofloxacin (500 mg) and loperamide for noninflammatory diarrhea. Although nausea after dosing is uncommon, it is more frequently associated with azithromycin than with levofloxacin. Future studies should focus on determining whether lower doses of azithromycin would decrease the frequency of nausea and decrease treatment costs without affecting efficacy.

Enteric pathogens associated with diarrhea in children in Fayoum, Egypt.

In a cross-sectional study of children <60 months old from Fayoum, Egypt, presenting with diarrhea, 46% (162/356) had detectable enteric pathogens. Bacterial pathogens were identified in 25% (89/356), whereas rotavirus and Cryptosporidium were detected in 21% (54/253) and 15% (39/253), respectively. Cryptosporidium is an important pathogen in this region.

Self-reported description of diarrhea among military populations in operations Iraqi Freedom and Enduring Freedom.

BACKGROUND: Infectious diarrhea is among the most common medical problems associated with military deployments and has been reported as a frequent problem for troops currently deployed to Iraq and Afghanistan. Lacking is information describing clinical presentation, risk behaviors, and treatment of travelers' diarrhea in this population. METHODS: An anonymous cross-sectional survey was conducted among 15,459 US military personnel deployed to Southwest Asia during 2003 to 2004. RESULTS: Overall, diarrhea was commonly reported (76.8% in Iraq and 54.4% in Afghanistan) and was frequently severe (more than six stools/d) (20.8% in Iraq and 14.0% in Afghanistan) or associated with fever (25.8%), vomiting (18% with diarrhea and 16.5% without), persistent symptoms (>14 d, 9.8%), or chronic symptoms (>30 d, 3.3%). Diarrhea was associated with time spent off military compounds and eating local food. Over 80% of respondents sought care for their symptoms, usually at the lowest echelon of care (field medic), and were most often treated with either loperamide or an antibiotic. Self-treatment with loperamide or Pepto-Bismol was also common and successful with only 9% of self-treated individuals reporting seeking further medical care. CONCLUSIONS: Infectious diarrhea is a common problem for US military personnel, and associated fevers and vomiting are more common than in past conflicts in the region. As with past studies, time spent off base and local food consumption, both more common in Iraq than Afghanistan, continue to be the most important risk factors for acquiring diarrhea. The majority of soldiers reported seeking care for diarrhea, but appropriate treatment, including self-treatment with over-the-counter medicines, was generally successful. Further studies should be conducted to evaluate appropriate treatment algorithms, including the use of self-treatment, for deployed military personnel.

Enterotoxigenic Escherichia coli colonization factor types collected from 1997 to 2001 in US military personnel during operation Bright Star in northern Egypt.

Operation Bright Star (OBS) is a biennial, multinational exercise in Egypt involving 15000 US troops. Consistent with past observations in deployed troops, diarrhea is the most significant cause of morbidity. Focused efforts are ongoing to develop vaccines against the most common pathogens affecting our troops. As part of these efforts, diarrhea surveillance was conducted during OBS to monitor pathogens associated with illness and to identify new vaccine targets. A retrospective review was conducted of prior studies with similar methods. Soldiers with diarrhea presenting to the OBS clinic provided a stool sample that was inoculated into Carey-Blair transport media. Within 3 days, the Cary-Blair tubes were transported to the Naval Medical Research Unit no. 3 in Cairo where bacterial culture was performed. As part of the evaluation, 5 Escherichia coli-like colonies were collected and tested for toxin production using the GM1-ELISA. Toxin-positive isolates were further tested for colonization factors (CF) by a dot-blot assay using a standardized panel of monoclonal antibodies against CFA/I, CS1-CS7, CS17, CS8 (CFA/III), CS12 (PCFO159), and CS14 (PCFO166). Enterotoxigenic E. coli (ETEC) was the most frequently isolated pathogen during each OBS from which data were collected. The rate of ETEC-associated diarrhea ranged from 22% to 58%. Over time, there were dramatic shifts in the frequency and distribution of CFs. Over the 5 years of study, an increasing number of ETEC isolates had no known CF identified, and in 2001, only 40% of ETEC was associated with known CFs. The most commonly identified CF was CS6. Diarrheal disease, particularly ETEC, continues to be a common malady among US military personnel deployed to Egypt. We have identified ETEC CF types, especially CS6, which should be considered potential vaccine candidates. However, despite intensive testing, CFs could not be identified in most of the ETEC isolated, highlighting the need for further studies to identify novel CFs and alternative vaccine targets.

Impact of illness and non-combat injury during Operations Iraqi Freedom and Enduring Freedom (Afghanistan).

Historically, non-combat injuries and illnesses have had a significant impact on military missions. We conducted an anonymous cross-sectional survey to assess the prevalence and impact of common ailments among U.S. military personnel deployed to Iraq or Afghanistan during 2003-2004. Among 15,459 persons surveyed, diarrhea (76.8% in Iraq and 54.4% in Afghanistan), respiratory illness (69.1%), non-combat injuries (34.7%), and leishmaniasis (2.1%) were commonly reported. For all causes, 25.2% reported that they required intravenous fluids, 10.4% required hospitalization, and 5.2% required medical evacuation. Among ground units, 12.7% reported that they missed a patrol because of illness, and among air units, 11.7% were grounded because of illness. The incidence of diarrhea and respiratory infections doubled from the pre-combat to combat phases, and the perceived adverse impact of these illnesses on the unit increased significantly during the combat phase. Despite technologic advances in warfare and preventive medicine, illness and non-combat injuries have been common during operations in Iraq and Afghanistan, resulting in frequent transient decreases in operational efficiency.

Universal high-level primary metronidazole resistance in Helicobacter pylori isolated from children in Egypt.

Antimicrobial susceptibility testing was performed on 48 isolates of Helicobacter pylori recovered from Egyptian children undergoing routine endoscopies. The isolates were universally highly resistant to metronidazole, but resistance to other tested antimicrobial agents was rare (4% for clarithromycin, erythromycin, and azithromycin resistance versus 2% for ciprofloxacin and ampicillin resistance). Use of metronidazole for the treatment of H. pylori in Egypt should be avoided.