Dennis D. Juranek

Epidemic Toxoplasmosis Associated with Infected Cats

In October, 1977, an outbreak of toxoplasmosis occurred in patrons of a riding stable in Atlanta, Georgia; 37 became ill with toxoplasmosis or had serologic evidence by indirect fluorescent-antibody test of acute infection with Toxoplasma gondii (titer greater than or equal to 1:4096 or a positive fluorescent-antibody test for toxoplasma antibodies). Forty-nine additional patrons did not become ill. Two of the three adult cats from the stable were seropositive for toxoplasma, which was also recovered from the tissues of two kittens and four mice trapped near the stable. Patrons who spent most of their time at the end of the stable where a cat had defecated had the highest incidence of infection. Patrons who attended the stable daily had a higher attack rate than those who attended less frequently. No common meals were consumed, and dietary histroy eliminated meat as the source of infection. The data suggest that toxoplasma oocysts were the source of the infection.

Babesiosis in Washington State: A New Species of Babesia?

Babesiosis is an intraerythrocytic protozoan infection, transmitted by ticks, and characterized by malaria-like symptoms and hemolytic anemia. The first reported zoonotic cases in Europe and the United States occurred in 1956 [1] and 1966 [2], respectively. In Europe, cases of this infection have generally been in splenectomized persons infected with the cattle parasites Babesia divergens and Babesia bovis [3, 4], which are thought to be maintained by Ixodes ricinus ticks. No national surveillance system for babesiosis exists in the United States, but hundreds of cases have been reported [4, 5]. Most have been attributed to infection with Babesia microti, a rodent parasite maintained by Ixodes dammini ticks, the primary vector of the agent of Lyme disease (Borrelia burgdorferi). Human babesiosis is endemic on various coastal islands in the northeastern United States, such as Nantucket Island and Marthas Vineyard, Block Island, Long Island, and Shelter Island, and in mainland Connecticut [6]. Cases acquired in Wisconsin have been reported as well [7, 8]. Asplenic, immunocompromised, and elderly persons infected with B. microti are at greatest risk for clinical illness [5, 7, 9-13], which may be severe, whereas other infected persons commonly are asymptomatic or only mildly symptomatic. Only three human cases of babesiosis acquired in the western United States have been reported previously, all of which occurred in splenectomized patients in California [2, 14, 15]; the infecting species was not definitively identified for any of these cases. In September 1991, the first recognized case of babesiosis acquired in Washington State was diagnosed. We present the clinical details of this case, which occurred in an apparently immunocompetent person, and provide evidence that it was not caused by B. microti. We also provide results of 1) serologic testing that was done in an attempt to identify the species of the patients Babesia isolate [referred to as WA1]; 2) experimental inoculations of various mammalian species to determine WA1s host specificity; 3) a comparison of the DNA hybridization patterns of WA1, B. microti, and B. gibsoni using a Babesia-specific, ribosomal-DNA (rDNA) probe [16]; 4) a serosurvey of the patients family members and neighbors for antibody to WA1; and 5) attempts to identify WA1s reservoir host and tick vector. Case Report A 41-year-old man from a rural forested area in south-central Washington State went to a local emergency room on 15 September 1991 because of a 1-week history of fever, rigors, anorexia, rhinorrhea, cough, and headache. He had previously been in good health, was not taking any medications, and had never had a blood transfusion. He had a dog, two cats, and two head of cattle and was exposed daily to tick habitats, but he did not recall any tick bites. He had not been outside the Washington-Oregon border region in many years and had never been in areas reported to be endemic for babesiosis or malaria. On evaluation, he had a few rales in his left-lung field and a platelet count of 48 109/L. He was treated for a presumed bronchopneumonia, with intravenous cefazolin to be followed with oral cefixime, and was sent home. He was hospitalized the next day (September 16) because of persistent fever, severe rigors, and dark-colored urine. He had a temperature of 39.5 C, tenderness in both upper quadrants of his abdomen without hepatosplenomegaly, a normal hematocrit (0.44) and leukocyte count, a platelet count of 46 109/L, 1+ occult blood on urine-dipstick analysis with no cells detected microscopically, a normal chest radiograph, and blood and urine culture results that were negative for bacteria. He was treated with cefazolin and gentamicin without improvement. On September 18, his temperature peaked at 40.4 C; his hematocrit was 0.36, his serum lactate dehydrogenase level was 21.34 kat/L (1280 U/L), and his total bilirubin level was 20.5 mol/L (1.2 mg/dL). Intraerythrocytic ring forms attributed to Plasmodium falciparum malaria were noted on his peripheral blood smear. He was treated with mefloquine and sent home at his request. He was rehospitalized the next day (September 19) with a temperature of 40 C, rigors, and vomiting. On re-examination of his blood smears from September 15 and 18, intraerythrocytic ring forms (in 1.2% and 3.0% of the erythrocytes) were noted as well as tetrad forms characteristic of Babesia (Figure 1). Therapy with oral quinine (650 mg, three times daily) and intravenous clindamycin (600 mg, four times daily) was begun on September 20, with symptomatic improvement by the next day. By September 23, he was afebrile, his hematocrit was 0.35, the parasitemia had decreased from 3.7% (September 20) to 0.4%, and his platelet count had increased to 143 109/L. On September 24, he was sent home on oral quinine and clindamycin (600 mg, three times daily) to complete a 10-day course of therapy. Figure 1. Photographs of Giemsa-stained peripheral blood smears from a patient who acquired babesiosis in Washington State. Left. Right. On September 30, he was evaluated because of a diffuse urticarial rash. His blood smear was normal, and he was treated with a 12-day tapering course of prednisone for a presumed hypersensitivity reaction. On November 3, when he felt feverish and had a headache, his temperature was 37.5 C, his hematocrit 0.34, and he had a detectable parasitemia of <1%. Urticaria recurred after a dose of quinine (650 mg). Although he appeared to be improving without further therapy for babesiosis, he was treated with intravenous clindamycin (1.2 grams, twice daily for 10 days). His hematocrit decreased to 0.28 on November 7; his anemia had resolved by December 12. Because of slowly resolving fatigue, he did not return to work until 6 January 1992. No parasites were detected on his blood smear in December 1991 or on smears in January, March, July, and September 1992, during which time he remained asymptomatic. Evaluation of his immunologic status with a Western-blot test for human immunodeficiency virus; a liver-spleen scan; quantitative immunoglobulins (including immunoglobulin-G subtypes); and serologic testing for antibody to tetanus toxoid, rubella virus, and streptolysin O, indicated normal results. Methods Serologic Studies Serum specimens from the patient were tested at the Centers for Disease Control and Prevention (CDC) in serial fourfold dilutions by indirect immunofluorescent antibody (IFA) testing [17] for antibody to B. microti and the patients isolate (WA1), which was propagated in hamsters inoculated with his blood (see below). A titer of at least 64 to B. microti was considered positive. Stored serum specimens from patients in the northeastern United States with B. microti-antibody titers ranging from 64 to greater than 4096 and blood smears with intraerythrocytic ring forms were assayed for IFA reactivity with WA1. In another laboratory (University of California at Davis [UCD]) with a different IFA protocol [18], serum from the patient was assayed in serial twofold dilutions for reactivity with various Babesia isolates maintained by passage in animals (Table 1). A titer of at least 320 to B. microti was considered positive. Fluorescein-labeled, affinity-purified antibody to human IgG (Kirkegaard & Perry, Gaithersburg, Maryland) was used as the secondary antibody. Blood smears from the patient were examined for B. bovis, Babesia equi, and Babesia bigemina antigens by direct immunofluorescence testing with monoclonal antibodies specific for these species [24-26]. Table 1. Indirect Immunofluorescent Antibody Reactivity of Serum from November 1991 from a Patient Who Acquired Babesiosis (Isolate WA1) in Washington State* Animal Inoculations Whole blood specimens from the patient were inoculated intraperitoneally (1-mL inocula) into at least two hamsters (Mesocricetus auratus) or jirds (Mongolian gerbils; Meriones unguiculatus). Giemsa-stained thin smears of blood from the inoculated animals were examined (at least 25 oil-immersion fields per slide) weekly for 6 to 8 weeks. Erythrocytes from hamsters infected with WA1 were washed in Pucks Saline G and were inoculated into a splenectomized 1-year-old female golden Labrador retriever (5.6 109 parasitized erythrocytes were administered intravenously and an equal number, subcutaneously) and into a hamster (9 106 parasitized erythrocytes, intraperitoneally). During the 34-day monitoring period, the dogs clinical status and hematocrit were checked daily for 20 days and then 3 times weekly, and thin smears were examined (>5000 erythrocytes/slide) daily through day 20 and then twice weekly. Pre-and postinoculation serum samples from the dog were assayed for IFA reactivity (UCD) with WA1, B. microti (GI [20] and P20 isolates), and B. gibsoni. Southern-Blot Analysis Babesia-infected erythrocytes (P1 pellets) were obtained as previously described [16]; erythrocytes infected with WA1, a human isolate of B. microti (2Bm) [16], and a canine isolate of B. gibsoni (6Bg) were used. Control mammalian leukocytes were separated from uninfected blood of a hamster and a dog by differential centrifugation (400 x g, 4 C, 20 min) on Ficoll-paque (Pharmacia LDB Biotechnology, Piscataway, New Jersey) gradients. After Babesia and leukocyte DNA samples were prepared [27], approximately 1 g of each DNA sample was digested with restriction endonucleases (HindIII or HaeIII; Boehringer Mannheim, Indianapolis, Indiana), as previously described [16]. DNA fragments were separated by electrophoresis in horizontal 0.8% (weight/volume) agarose gels in 45 mM Tris-borate and 1 mM ethylenediaminetetraacetic acid at 40 V for 16 to 18 hours. A Babesia-specific rDNA probe was hybridized to Southern blots of the restriction-endonuclease- digested DNAs; the probe had been produced by polymerase chain reaction amplification of sequences from B. microti DNA, with universal primers directed against highly conserved portions of the nuclear sma

Human babesiosis on Nantucket Island. Evidence for self-limited and subclinical infections.

Between 1969 and 1975, seven patients infected with Babesia microti, a tick-borne intraerythrocytic protozoan parasite, were reported from Nantucket Island, Massachusetts.1 2 3 Although all seven p...

A Multiyear Prospective Study of the Risk Factors for and Incidence of Diarrheal Illness in a Cohort of Peace Corps Volunteers in Guatemala

Diarrheal illness is the most common medical disorder among travelers from developed to developing nations (1, 2). It also is common among expatriate residents in developing countries (3-5). To prevent diarrheal illness, travelers and expatriates are urged to follow various dietary recommendations (for example, boil it, cook it, peel it, or forget it). However, the benefits of following such recommendations have been questioned. Several retrospective studies have shown that such practices are not protective or are associated with increased risk for diarrheal illness (6-11). On the other hand, a study in which dietary data were collected during the first few days of travel did find that the incidence of diarrheal illness increased along with the number of certain types of dietary behaviors (12). In addition, some retrospective and short prospective studies have shown that the location where food was eaten or bought was important, although the studies varied in their reports of which locations (for example, street vendors) were risky (4, 13-17). To assess the risk factors for and the incidence of diarrheal illness among Americans living in a developing country and to revisit the issue of the usefulness of traditional dietary recommendations, we conducted a prospective longitudinal study of a cohort of Peace Corps volunteers in rural Guatemala. Participants recorded daily dietary and symptom data throughout their stay of more than 2 years abroad. To our knowledge, no other study has monitored expatriates so closely and for so long about the risk factors for and incidence of diarrheal illness. Methods Study Participants In October 1991, we recruited participants among a group of Peace Corps volunteers en route to Guatemala. Participants provided informed consent, and the study was approved by the institutional review board of the Centers for Disease Control and Prevention. Participants contributed person-days to the study from the time of their arrival in Guatemala until their Peace Corps service ended or they withdrew from the study. Data Collection Participants spent an average of 1 to 2 minutes per day recording data on a structured log, which had one row per day of the month, columns for placing a maximum of one checkmark per day by specific exposures and symptoms the participants had had, and space for comments. Exposures were grouped in sections, as shown in Table 1. Participants provided additional information on beginning- and close-of-service questionnaires. Table 1. Exposure Data and Univariate Analyses of Risk Factors for Diarrheal Illness among Peace Corps Volunteers in Guatemala Definitions We classified person-days as belonging to diarrheal or wellness episodes. To capture various patterns of illness that can result from infectious gastroenteritides, we used a multicomponent definition of a diarrheal episode. Given that participants had multiple episodes, we established criteria for their beginning and end, striving to minimize the likelihood of classifying relapses as new episodes and to maximize the likelihood that participants truly were well and behaved accordingly during the exposure period for each episode. A participant was considered to have had a diarrheal episode if criteria for one or more of the following three components of the definition were met: 1) three or more loose or watery stools and one or more other symptoms (that is, nausea, vomiting, abdominal cramps, visible blood in stool, or self-reported fever) during the same 24-hour period [11], 2) two loose or watery stools and two or more other symptoms during the same 24-hour period, or 3) six or more loose or watery stools during a 24- to 72-hour period. The beginning of a new diarrheal episode and the end of the previous episode had to be separated by 7 or more consecutive days with at most 1 loose or watery stool per day and no other symptoms. Days with residual symptoms were included in the preceding diarrheal episode. If 7 or more symptom-free days occurred, they were included in wellness episodes, as were other days that did not otherwise meet criteria for diarrheal episodes. Statistical Analysis To identify risk factors for diarrheal illness, we compared the exposures (for example, drinking tap water) that participants had had at least once in the 7-day period of wellness (that is, the exposure period) that immediately preceded the first day of a diarrheal episode with exposures during 7-day wellness periods not otherwise associated with a diarrheal episode (that is, before every eighth day of wellness). To standardize the duration of the exposure period, we excluded leftover wellness periods of less than 7 days. Exposures were classified as having occurred at least once or never during the exposure period. We calculated univariate relative risks for diarrheal illness by Poisson regression analyses. We then conducted multivariate Poisson regression analyses to model illness as a function of specific exposures and to generate summary relative risks across all participants. To account for correlated observations, given that daily data were provided, we used the GENMOD procedure and incorporated the generalized estimating equations option (SAS Institute, Inc., Cary, North Carolina). We assumed that the correlation between any two periods of exposure was the same. We constructed separate models of the variables from each section of the log (for example, water sources) by progressively removing variables that were not associated with illness (P >0.10). We then developed a model from the section variables most strongly associated with illness. Variables from the latter model were included in a model that accounted for the amount of time to date in Guatemala. All models controlled for age and sex, and we tested for ageexposure and sexexposure interactions. We compared proportions by using the chi-square test and ratios by using the t-statistic. When appropriate, we used SUDAAN 7.5 software (Research Triangle Institute, Research Triangle Park, North Carolina), which accounts for correlated observations. Statistical significance was set at a P value of 0.05 or less. Results Study Participants Of 65 eligible Peace Corps volunteers, 36 (55.4%) participated in the study. The 36 participants had a median age of 24 years (range, 22 to 70 years; 23 [63.9%] were<30 years), and the 29 nonparticipants had a median age of 22 years (range, 22 to 65 years). Eighteen participants (50%) and 11 nonparticipants (37.9%) were women (P =0.33). Most participants remained in the study throughout their Peace Corps service, which began in late October 1991 and typically ended in late 1993 or early 1994. Ten participants (27.8%) either left the Peace Corps early (8 after a median of 10 months) or withdrew from the study (2 after 10 or 15 months); 9 nonparticipants (31.0%) left the Peace Corps prematurely after a median of 9.5 months. Overall, the 36 participants contributed 64.9 person-years (23 689 person-days) to the study (median, 2.2 years per person [range, 0.4 to 2.5]). The compliance rate for monthly submission of a log was 98%. Of the 26 participants (72.2%) who completed a close-of-service questionnaire, 11 (42.3%) reported that they usually completed the log daily (compared with recording data for multiple days simultaneously). Episodes of Diarrhea Participants commonly had loose or watery stools. They had at least one such stool (maximum, 20) on 9.2% of person-days (n =2190) and at least three such stools on 3.9% of person-days (n =915). They had 307 episodes that met the criteria for diarrheal episodes (median, 7 per person [range, 1 to 27]). The numbers of episodes that fulfilled criteria for the first, second, and third components of the definition of an episode were 232 (75.6%), 54 (17.6%), and 236 (76.9%), respectively; 26 episodes (8.5%) met criteria for all three components. The 307 episodes lasted a median of 4 days (range, 1 to 112; 75% lasted 11 days or fewer) and a total of 10.1% of person-days (n =2400) (Table 2). For approximately one quarter of the episodes, the duration might have been influenced by antibiotic or antidiarrheal therapy. Successive episodes were separated by a median of 33 days (range, 7 to 350 days). Table 2. Symptoms Experienced by Peace Corps Volunteers in Guatemala The date of onset for each persons first episode ranged from a few days to more than 6 months after arrival in Guatemala. The incidence density of new episodes was 4.7 per person-year for the study as a whole, 6.1 for the first 6-month period, 5.2 for the second 6-month period, and 3.6 thereafter. The occurrence of episodes was not markedly seasonal (Figure). Figure. Incidence of diarrheal episodes over time among Peace Corps volunteers in Guatemala. Risk Factors Table 1 provides data about the frequency at which potentially risky exposures occurred. The overall number of such exposures recorded per person per day on the logs (counting all exposures from Table 1 except those related to travel) was 1.37 for the study participants as a group. The number per day was higher for persons younger than 30 years of age than for older persons (1.54 compared with 1.03; P =0.004), for persons who had more than seven diarrheal episodes (the overall median number of episodes) than for those who had seven or fewer (1.57 compared with 1.15; P =0.041), and on days when participants were elsewhere in Guatemala (not including Guatemala City) for at least part of the day rather than in their usual work area (1.87 compared with 1.03; P <0.001). The number per day was similar for men and women (1.41 compared with 1.34; P =0.75) and during the first and second years of the study (1.33 compared with 1.37; P =0.69). In univariate Poisson regression analyses (Table 1), the following exposures significantly increased risk for diarrheal illness: drinking water of unknown source; eating food prepared by a Guatemalan friend or family; eating food from a comedor (a small, working-cl

Toxoplasma gondii Isolated from Amniotic Fluid

&NA; A pregnant woman contracted toxoplasmosis from exposure to oocysts shed by cats. She underwent amniocentesis for a therapeutic abortion, and Toxoplasma gondii was isolated from the amniotic fluid and placenta. This method may be useful in determining whether the fetus is infected in cases of toxoplasmosis acquired during pregnancy.