Elizabeth Blanton

Typhoid fever in the United States, 1999-2006.

CONTEXT Typhoid fever in the United States has increasingly been due to infection with antimicrobial-resistant Salmonella ser Typhi. National surveillance for typhoid fever can inform prevention and treatment recommendations. OBJECTIVE To assess trends in infections with antimicrobial-resistant S. Typhi. DESIGN Cross-sectional, laboratory-based surveillance study. SETTING AND PARTICIPANTS We reviewed data from 1999-2006 for 1902 persons with typhoid fever who had epidemiologic information submitted to the Centers for Disease Control and Prevention (CDC) and 2016 S. Typhi isolates sent by participating public health laboratories to the National Antimicrobial Resistance Monitoring System Laboratory at the CDC for antimicrobial susceptibility testing. MAIN OUTCOME MEASURES Proportion of S. Typhi isolates demonstrating resistance to 14 antimicrobial agents and patient risk factors for antimicrobial-resistant infections. RESULTS Patient median age was 22 years (range, <1-90 years); 1295 (73%) were hospitalized and 3 (0.2%) died. Foreign travel within 30 days of illness was reported by 1439 (79%). Only 58 travelers (5%) had received typhoid vaccine. Two hundred seventy-two (13%) of 2016 isolates tested were resistant to ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole (multidrug-resistant S. Typhi [MDRST]); 758 (38%) were resistant to nalidixic acid (nalidixic acid-resistant S. Typhi [NARST]) and 734 NARST isolates (97%) had decreased susceptibility to ciprofloxacin. The proportion of NARST increased from 19% in 1999 to 54% in 2006. Five ciprofloxacin-resistant isolates were identified. Patients with resistant infections were more likely to report travel to the Indian subcontinent: 85% of patients infected with MDRST and 94% with NARST traveled to the Indian subcontinent, while 44% of those with susceptible infections did (MDRST odds ratio, 7.5; 95% confidence interval, 4.1-13.8; NARST odds ratio, 20.4; 95% confidence interval, 12.4-33.9). CONCLUSION Infection with antimicrobial-resistant S. Typhi strains among US patients with typhoid fever is associated with travel to the Indian subcontinent, and an increasing proportion of these infections are due to S. Typhi strains with decreased susceptibility to fluoroquinolones.

Recipes for foodborne outbreaks: a scheme for categorizing and grouping implicated foods.

BACKGROUND To better understand the sources of foodborne illness, we propose a scheme for categorizing foods implicated in investigations of outbreaks of foodborne diseases. Because nearly 2000 foods have been reported as causing outbreaks in the United States, foods must be grouped for meaningful analyses. METHODS We defined a hierarchy of 17 mutually exclusive food commodities. We defined the following three commodity groups from which nearly all food is derived: aquatic animals, land animals, and plants. We defined three commodities in aquatic animals, six in land animals, and eight in plants. We considered each food as a set of ingredients composed of one or more commodities. We defined a simple food as one made of ingredients that are all in one commodity and a complex food as one containing ingredients in more than one commodity. We determined likely ingredients using a panel of epidemiologists and a web-based search process. RESULTS We assigned 1709 (95%) of the 1794 foods implicated in outbreaks of foodborne diseases reported to Centers for Disease Control and Prevention from 1973 to 2006. Of those, 987 (57%) were simple foods and 722 (43%) were complex foods. DISCUSSION This categorization may serve as an input for modeling the attribution of human illness to specific food commodities and could be used by policy makers, health officials, regulatory agencies, and consumer groups to evaluate the contribution of various food commodities to illness.

Sodium Dichloroisocyanurate Tablets for Routine Treatment of Household Drinking Water in Periurban Ghana: A Randomized Controlled Trial

We conducted a randomized, placebo-controlled, triple-blinded trial to determine the health impact of daily use of sodium dichloroisocyanurate (NaDCC) tablets for household drinking water treatment in periurban Ghana. We randomized 240 households (3,240 individuals) to receive either NaDCC or placebo tablets. All households received a 20-liter safe water storage vvessel. Over 12 weeks, 446 diarrhea episodes (2.2%) occurred in intervention and 404 (2.0%) in control households (P = 0.38). Residual free chlorine levels indicated appropriate tablet use. Escherichia coli was found in stored water at baseline in 96% of intervention and 88% of control households and at final evaluation in 8% of intervention and 54% of control households (P = 0.002). NaDCC use did not prevent diarrhea but improved water quality. Diarrhea rates were low and water quality improved in both groups. Safe water storage vessels may have been protective. A follow-up health impact study of NaDCC tablets is warranted.

Ciprofloxacin-Resistant Salmonella enterica Serotype Typhi, United States, 1999–2008

We report 9 ciprofloxacin-resistant Salmonella enterica serotype Typhi isolates submitted to the US National Antimicrobial Resistance Monitoring System during 1999–2008. The first 2 had indistinguishable pulsed-field gel electrophoresis patterns and identical gyrA and parC mutations. Eight of the 9 patients had traveled to India within 30 days before illness onset.

Diarrhea prevention in people living with HIV: an evaluation of a point-of-use water quality intervention in Lagos, Nigeria

Abstract Diarrhea is a leading cause of morbidity and mortality in people living with HIV (PLHIV) in Africa. The impact of a point-of-use water chlorination and storage intervention on diarrheal-disease risk in a population of HIV-infected women in Lagos, Nigeria was evaluated. A baseline survey was performed, followed by six weeks of baseline diarrhea surveillance consisting of weekly home visits, distribution of free water chlorination products and safe storage containers to project participants, and continued weekly home-based diarrhea surveillance for 15 additional weeks. To confirm use of the water chlorination product, during each home visit, stored water was tested for residual chlorine. About 187 women were enrolled. At baseline, 80% of women had access to improved water supplies and 95% had access to sanitation facilities. Following distribution of the intervention, water stored in participants’ households was observed to have residual chlorine during 50–80% of home visits, a sign of adherence to recommended water-treatment practices. Diarrhea rates in project participants were 36% lower in the post-intervention period than during the baseline period (p=0.04). Diarrhea rates were 46% lower in the post-intervention period than the baseline period among project participants who were confirmed to have residual chlorine in stored water during 85% or more of home visits (p=0.04); there was no significant difference in diarrhea rates between baseline and post-intervention periods in participants confirmed to have residual chlorine in stored water during less than 85% of home visits. The percent change in diarrhea rates between baseline and post-intervention surveillance periods was statistically significant among non-users of prophylactic antibiotics (−62%, p=0.02) and among persons who used neither prophylactic antibiotics nor antiretroviral treatment (−46%, p=0.04). Point-of-use water treatment was associated with a reduced risk of diarrhea in PLHIV. Regular water treatment was required to achieve health benefits.

Household water disinfection in Hurricane-affected communities of Louisiana: implications for disaster preparedness for the general public

OBJECTIVES Thousands of Louisiana residents were asked to boil water because of widespread disruptions in electricity and natural gas services after Hurricane Rita. We sought to assess awareness of boil water orders and familiarity with household water disinfection techniques other than boiling. METHODS We conducted a cross-sectional survey in randomly selected mobile home communities in Louisiana. RESULTS We interviewed 196 respondents from 8 communities, which had boil water orders instituted. Of 97 who were home while communities were still under orders to boil water, 30 (31%) were aware of the orders and, of those, 24 (80%) said the orders were active while they were living at home; of the 24, 10 (42%) reported boiling water. Overall, 163 (83%) respondents were aware of a method of water disinfection at the household level: boiling (78%), chlorination (27%), and filtration (25%); 87% had a container of chlorine bleach at home. CONCLUSIONS Few hurricane-affected respondents were aware of boil water orders and of alternate water disinfection techniques. Most had access to chlorine and could have practiced household chlorination if disruption in natural gas and electricity made boiling impossible.

Emergency water treatment with bleach in the United States: the need to revise EPA recommendations.

During emergencies in the United States, the Environmental Protection Agency (EPA) currently recommends using bottled water, or boiling or treating water by adding 1/8 teaspoon (or 8 drops) of bleach to 1 gal of water. This bleach recommendation is internally inconsistent, a relatively high chlorine dose (5.55-8.67 mg/L), and unsupported by evidence. In this study, bleach was added in three different dosages to six waters available to emergency-affected populations in each of six states; free chlorine residual (FCR) and Escherichia coli/total coliforms were measured 1-24 h after treatment. Data were analyzed using four efficacy criteria. Results indicated the dosages in the current EPA recommendation are unnecessarily high to ensure (1) maintenance of FCR for 24 h after treatment, (2) absence of E. coli/total coliforms, and (3) establishment of a CT-factor sufficient to inactivate Giardia lamblia and enteric viruses 1 h after treatment. Additionally, emergency-prone populations did not have the materials to complete treatment with bleach in their household. Therefore, we recommend EPA review and revise the current recommendation to establish an internally consistent, criteria-based recommendation that is usable by emergency-affected populations. We also recommend investigating the use of new or commercially available water treatment products for emergency response in the United States.

Sodium hypochlorite dosage for household and emergency water treatment: updated recommendations

Household water treatment with chlorine can improve the microbiological quality of household water and reduce diarrheal disease. We conducted laboratory and field studies to inform chlorine dosage recommendations. In the laboratory, reactors of varying turbidity (10-300 NTU) and total organic carbon (0-25 mg/L addition) were created, spiked with Escherichia coli, and dosed with 3.75 mg/L sodium hypochlorite. All reactors had >4 log reduction of E. coli 24 hours after chlorine addition. In the field, we tested 158 sources in 22 countries for chlorine demand. A 1.88 mg/L dosage for water from improved sources of <5 or <10 NTU turbidity met free chlorine residual criteria (≤2.0 mg/L at 1 hour, ≥0.2 mg/L at 24 hours) 91-94% and 82-87% of the time at 8 and 24 hours, respectively. In unimproved water source samples, a 3.75 mg/L dosage met relaxed criteria (≤4.0 mg/L at 1 hour, ≥0.2 mg/L after 24 hours) 83% and 65% of the time after 8 and 24 hours, respectively. We recommend water from improved/low turbidity sources be dosed at 1.88 mg/L and used within 24 hours, and from unimproved/higher turbidity sources be dosed at 3.75 mg/L and consumed within 8 hours. Further research on field effectiveness of chlorination is recommended.

A rapid assessment of drinking water quality in informal settlements after a cholera outbreak in Nairobi, Kenya

Populations living in informal settlements with inadequate water and sanitation infrastructure are at risk of epidemic disease. In 2010, we conducted 398 household surveys in two informal settlements in Nairobi, Kenya with isolated cholera cases. We tested source and household water for free chlorine residual (FCR) and Escherichia coli in approximately 200 households. International guidelines are ≥0.5 mg/L FCR at source, ≥0.2 mg/L at household, and <1 E. coli/100 mL. In these two settlements, 82% and 38% of water sources met FCR guidelines; and 7% and 8% were contaminated with E. coli, respectively. In household stored water, 82% and 35% met FCR guidelines and 11% and 32% were contaminated with E. coli, respectively. Source water FCR≥0.5 mg/L (p=0.003) and reported purchase of a household water treatment product (p=0.002) were associated with increases in likelihood that household stored water had ≥0.2 mg/L FCR, which was associated with a lower likelihood of E. coli contamination (p<0.001). These results challenge the assumption that water quality in informal settlements is universally poor and the route of disease transmission, and highlight that providing centralized water with ≥0.5 mg/L FCR or (if not feasible) household water treatment technologies reduces the risk of waterborne cholera transmission in informal settlements.