Typhoid fever in the United States, 1985-1994: changing risks of international travel and increasing antimicrobial resistance.

BACKGROUND: Typhoid fever is a potentially fatal illness common in the less industrialized world. In the United States, the majority of cases occur in travelers to other countries. METHODS: We reviewed surveillance forms submitted to the Centers for Disease Control and Prevention, Atlanta, Ga, for patients with culture-confirmed typhoid fever between 1985 and 1994. RESULTS: The Centers for Disease Control and Prevention received report forms for 2445 cases of typhoid fever. Median age of patients was 24 years (range, 0-89 years). Ten (0.4%) died. Seventy-two percent reported international travel within the 30 days before onset of illness. Six countries accounted for 80% of cases: Mexico (28%), India (25%), the Philippines (10%), Pakistan (8%), El Salvador (5%), and Haiti (4%). The percentage of cases associated with visiting Mexico decreased from 46% in 1985 to 23% in 1994, while the percentage of cases associated with visiting the Indian subcontinent increased from 25% in 1985 to 37% in 1994. The incidence of typhoid fever in US citizens traveling to the Indian subcontinent was at least 18 times higher than for any other geographic region. Complete data on antimicrobial susceptibility to ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole were reported for 330 (13%) Salmonella Typhi isolates. Isolates from 1990 to 1994 were more likely than isolates from 1985 to 1989 to be resistant to any of these antimicrobial agents (30% vs 12%; P<.001) and to be resistant to all 3 agents (12% vs 0.6%; P<.001). CONCLUSIONS: American travelers to less industrialized countries, especially those traveling to the Indian subcontinent, continue to be at risk for typhoid fever. Antimicrobial resistance has increased, and a quinolone or third-generation cephalosporin may be the best choice for empirical treatment of typhoid fever.

A multistate outbreak of Escherichia coli O157:H7 infections associated with consumption of mesclun lettuce.

BACKGROUND: An outbreak of Escherichia coli O157:H7 infections in Connecticut and Illinois during May 28 to June 27, 1996, was investigated to determine the source of infections. METHODS: Independent case-control studies were performed in both states. Pulsed-field gel electrophoresis (PFGE) was performed on E. coli O157:H7 isolates. A case-patient was defined as a Connecticut or northern Illinois resident with diarrhea whose stool culture yielded E. coli O157:H7 of the outbreak-associated PFGE subtype. Controls were town-, age-, and sex-matched to case-patients. We traced implicated lettuce to the farm level and performed environmental investigations to identify unsafe lettuce production practices. RESULTS: In Connecticut and Illinois, infection was associated with consumption of mesclun lettuce (Connecticut matched odds ratio [MOR], undefined; 95% confidence interval [CI], 3.4 to infinity; and Illinois MOR, undefined; 95% CI, 1.4 to infinity). We traced implicated lettuce to a single grower-processor. Cattle, a known E. coli O157:H7 reservoir, were found near the lettuce fields. Escherichia coli (an indicator of fecal contamination) was cultured from wash water and finished lettuce. A trace-forward investigation identified 3 additional states that received implicated lettuce; E. coli O157:H7 isolates from patients in 1 of these states matched the outbreak-associated PFGE subtype. CONCLUSIONS: This multistate outbreak of E. coli O157:H7 infections was associated with consumption of mesclun lettuce from a single producer. Molecular subtyping facilitated the epidemiological investigation. This investigation increased the knowledge about current production practices that may contribute to the contamination of lettuce by microbial pathogens. Lettuce production practices should be monitored for microbiological safety.

Impairment of a pregnant woman's acquired ability to limit Plasmodium falciparum by infection with human immunodeficiency virus type-1.

In Africa, the human immunodeficiency virus (HIV) is the most serious emerging infection and Plasmodium falciparum malaria is one of the most prevalent infectious diseases. Both infections have serious consequences in pregnant women, their fetuses, and infants. We examined the association between HIV and P. falciparum in pregnant women enrolled in a malaria chemoprophylaxis study in rural Malawi. Pregnant women (n = 2,946) were enrolled at their first antenatal clinic visit (mean 5.6 months of pregnancy), placed on one of three chloroquine regimens, and followed through delivery. Plasmodium falciparum parasitemia was measured at enrollment, monthly thereafter, at delivery, and 2-6 months postpartum; placental and newborn (umbilical cord blood) infection was measured for hospital-delivered infants. Serum collected during pregnancy was tested for antibodies to HIV by enzyme-linked immunoassay with Western blot confirmation. Parasitemia was detected in 46% of 2,946 women at enrollment and 19.1% at delivery; HIV seroprevalence was 5.5%. The prevalence and geometric mean density (GMPD) of parasitemia at enrollment and at delivery were higher in HIV-seropositive(+) than in HIV-seronegative(-) women (at enrollment: 57% prevalence and a GMPD of 1,558 parasites/mm3 versus 44% and 670/mm3, respectively; P < 0.0001; and at delivery: 35% and 1,589/mm3 versus 18% and 373/mm3; P < 0.0005). Placental infection rates were higher in HIV(+) compared with HIV(-) women, (38% versus 23%; P < 0.0005). This association was strongest in multigravidas. Compared with infants born to HIV(-) women, newborns born to HIV(+) women had higher rates of umbilical cord blood parasitemia. Both HIV(+) and HIV(-) women had similar rates of parasitemia 2-6 months postpartum. The HIV infection diminishes a pregnant woman's capacity to control P. falciparum parasitemia and placental and newborn infection, the major determinants of the impact of P. falciparum on fetal growth and infant survival.

PIP: During September 1987 to July 1989, in Malawi, clinical investigators enrolled 2946 pregnant women into a chemoprophylaxis study at their first prenatal care visit (mean, 5.6 months) at 4 rural sites in Mangochi District. They prescribed 1 of 3 chloroquine regimens to the women and followed them through delivery. The investigators measured Plasmodium falciparum parasitemia at enrollment, monthly thereafter, at delivery, and 2-6 months postpartum. For hospitalized infants, they measured parasitemia in the placenta and in the umbilical cord blood of the newborn. They also aimed to examine the association between HIV infection and malaria in pregnant women. 152 (5.5%) of the 2781 women for whom HIV test results and malaria blood smear examinations were available had confirmed HIV infection. Malaria parasitemia stood at 42% at enrollment and 19.1% at delivery. At enrollment, HIV-positive women had a higher malaria parasite prevalence rate than HIV-negative women (54.4% vs. 41.7%; relative risk [RR] = 1.31; p = 0.002). They also had a higher geometric mean density of parasitemia (1558 vs. 670/sq mm; p 0.0005). The parasite pattern was similar at delivery (34.7% vs. 18.2% [RR = 1.91] and 1589 vs. 373/sq mm, respectively; p 0.0005). The placenta of infants born in the hospital to HIV-positive mothers also had a higher prevalence of malaria parasites than those born in the hospital to HIV-negative mothers (38.2% vs. 22.5%; RR = 1.7; p = 0.0003). The prevalence of umbilical cord blood malaria infection was higher in infants born in the hospital to HIV-positive mothers than their counterparts (25.5% vs. 6.8%; RR = 3.76). At 2-6 months postpartum, the prevalence and density of malaria parasitemia rate did not differ significantly by HIV status. Parasitemia prevalence and density were higher in multigravida HIV-positive women than HIV-negative women but were similar in primigravid HIV-positive and HIV-negative women. These findings suggest that HIV infection reduces a pregnant woman's capacity to control P. falciparum parasitemia and placental and newborn infection.

Developing WHO guidelines with pragmatic, structured, evidence-based processes: A case study.

Many guidelines, including those produced by the World Health Organisation (WHO), have failed to adhere to rigorous methodological standards. Operational examples of guideline development processes may provide important lessons learned to improve the rigour and quality of future guidelines. To this end, this paper describes the process of developing WHO guidelines on prevention and care interventions for adults and adolescents living with HIV. Using a pragmatic, structured, evidence-based approach, we created an organising committee, identified topics, conducted systematic reviews, identified experts and distributed evidence summaries. Subsequently, 55 global HIV experts drafted and anonymously submitted guideline statements at the beginning of a conference. During the conference, participants voted on statements using scales evaluating appropriateness of the statements, strength of recommendation and level of evidence. After review of voting results, open discussion, re-voting and refinement of statements, a draft version of the guidelines was completed. A post-conference writing team refined the guidelines based on pre-determined guideline writing principles and incorporated external comments into a final document. Successes and challenges of the guideline development process were identified and are used to highlight current issues and debates in developing guidelines with a focus on implications for future guideline development at WHO.

Living with discordance: knowledge, challenges, and prevention strategies of HIV-discordant couples in Uganda.

Prevalence of HIV-discordance among couples in sub-Saharan Africa is high. Negative partners are at high risk of HIV infection but few HIV/AIDS service providers have developed effective counseling messages for HIV-discordant couples. To identify clients' explanations for discordance, challenges, and prevention strategies, 24 in-depth interviews and 4 focus group discussions were conducted with 32 female and 35 male members of HIV-discordant couples who sought HIV voluntary counseling and testing (VCT) in Uganda. In addition, counselor explanations for discordance were gathered from 62 counselor trainers during 3 interactive workshops. Misconceptions about discordance were widespread among clients and counselors. Common explanations included: the concept of a hidden infection not detectable by HIV tests, belief in immunity, the thought that gentle sex protected HIV-negative partners, and belief in protection by God. Such explanations for discordance reinforced denial of HIV risk for the negative partner within discordant couples and potentially increased transmission risk. Couples identified negotiation of sexual relations as their most formidable challenge. Prevention strategies included condom use, abstinence and separation of beds, contractual agreements for outside sexual partners, and relationship cessation. Discordant couples represent a critical risk group and improved counseling protocols that clearly explain discordance, emphasize high risk of transmission, and support risk reduction are urgently needed.

Detection of human immunodeficiency virus DNA and RNA in semen by the polymerase chain reaction.

Peripheral blood mononuclear cells (PBMC) and semen of 23 men infected with human immunodeficiency virus (HIV) were examined for the presence of HIV DNA and RNA using the polymerase chain reaction (PCR) and a nonisotopic detection assay. None of the men was receiving antiretroviral therapy at the time of collection. Semen samples were separated into cell-free seminal fluid, nonspermatozoal mononuclear cells (NSMC), and spermatozoa. All of the PBMC samples, 17 (74%) of 23 NSMC samples, and none of the spermatozoal samples were positive for HIV gag gene DNA. Of 23 cell-free seminal fluid samples, 15 (65%) were positive for HIV gag gene RNA by PCR. Cell-free HIV RNA was more likely to be present in the semen of men with less than 400 than in those with greater than or equal to 400 cells/mm3 (P less than .04) and was present in all patient with p24 antigen in serum. The presence of HIV DNA in NSMC samples was not related to CD4 cell count, disease status, or the presence of p24 antigen in the serum. This study shows that HIV nucleic acid can be detected by PCR in either the cell-free seminal fluid or NSMC of 87% of semen samples but not in the DNA of spermatozoa from HIV-infected men.

Factory outbreak of Escherichia coli O157:H7 infection in Japan.

To determine the cause of a July 1996 outbreak of Escherichia coli O157:H7 among factory workers in Kyoto, Japan, we conducted cohort and case-control studies. Eating radish sprout salad during lunch at the factory cafeteria had been linked to illness. The sprouts were traced to four growers in Japan; one had been associated with an outbreak of E. coli O157:H7 among 6,000 schoolchildren in Sakai earlier in July.

A massive epidemic of multidrug-resistant typhoid fever in Tajikistan associated with consumption of municipal water.

From 1 January through 30 June 1997, 8901 cases of typhoid fever and 95 associated deaths were reported in Dushanbe, Tajikistan. Of 29 Salmonella serotype Typhi isolates tested, 27 (93%) were resistant to ampicillin, chloramphenicol, nalidixic acid, streptomycin, sulfisoxazole, tetracycline, and trimethoprim-sulfamethoxazole. In a case-control study of 45 patients and 123 controls, Salmonella Typhi infection was associated with drinking unboiled water (matched odds ratio, 7; 95% confidence interval, 3-24; P<.001). Of tap water samples, 97% showed fecal coliform contamination (mean level, 175 cfu/100 mL). Samples taken from water treatment plants revealed that fecal coliform contamination occurred both before and after treatment. Lack of chlorination, equipment failure, and back-siphonage in the water distribution system led to contamination of drinking water. After chlorination and coagulation were begun at the treatment plants and a water conservation campaign was initiated to improve water pressure, the incidence of typhoid fever declined dramatically.