Laboratory-acquired parasitic infections from accidental exposures

Parasitic diseases are receiving increasing attention in developed countries in part because of their importance in travelers, immigrants, and immunocompromised persons. The main purpose of this review is to educate laboratorians, the primary readership, and health care workers, the secondary readership, about the potential hazards of handling specimens that contain viable parasites and about the diseases that can result. This is accomplished partly through discussion of the occupationally acquired cases of parasitic infections that have been reported, focusing for each case on the type of accident that resulted in infection, the length of the incubation period, the clinical manifestations that developed, and the means by which infection was detected. The article focuses on the cases of infection with the protozoa that cause leishmaniasis, malaria, toxoplasmosis, Chagas' disease (American trypanosomiasis), and African trypanosomiasis. Data about 164 such cases are discussed, as are data about cases caused by intestinal protozoa and by helminths. Of the 105 case-patients infected with blood and tissue protozoa who either recalled an accident or for whom the likely route of transmission could be presumed, 47 (44.8%) had percutaneous exposure via a contaminated needle or other sharp object. Some accidents were directly linked to poor laboratory practices (e.g., recapping a needle or working barehanded). To decrease the likelihood of accidental exposures, persons who could be exposed to pathogenic parasites must be thoroughly instructed in safety precautions before they begin to work and through ongoing training programs. Protocols should be provided for handling specimens that could contain viable organisms, using protective clothing and equipment, dealing with spills of infectious organisms, and responding to accidents. Special care should be exercised when using needles and other sharp objects.

Outbreak of cyclosporiasis associated with basil in Missouri in 1999

During the summer of 1999, an outbreak of cyclosporiasis occurred among attendees of 2 events held on 24 July in different counties in Missouri. We conducted retrospective cohort studies of the 2 clusters of cases, which comprised 62 case patients. The chicken pasta salad served at one event (relative risk [RR], 4.25; 95% confidence interval [CI], 1.80-10.01) and the tomato basil salad served at the other event (RR, 2.95; 95% CI, 1.72-5.07) were most strongly associated with illness. The most likely vehicle of infection was fresh basil, which was included in both salads and could have been grown either in Mexico or the United States. Leftover chicken pasta salad was found to be positive for Cyclospora DNA by means of polymerase chain reaction analysis, and 1 sporulated Cyclospora oocyst was found by use of microscopy. This is the second documented outbreak of cyclosporiasis in the United States linked to fresh basil and the first US outbreak for which Cyclospora has been detected in an epidemiologically implicated food item.

Multiyear prospective study of intestinal parasitism in a cohort of Peace Corps volunteers in Guatemala

We conducted a prospective, longitudinal study in a cohort of 36 Peace Corps volunteers (PCVs) in Guatemala to study the incidence and natural history of intestinal parasitic infections during the PCVs' >2-year overseas stay. PCVs collected stool specimens at least monthly and when ill with gastrointestinal symptoms. Of the 1,168 specimens tested, 453 (38.8%) were positive for at least one parasite and 48 (4.1%) were positive for a pathogenic parasite. A median interval of 187 days (range, 14 to 752 days) elapsed before the first documented parasitic infection, and the median intervals from arrival until subsequent infections (e.g., second or third) were >300 days. The PCVs had 116 episodes of infection with 11 parasites, including up to 4 episodes per PCV with specific nonpathogens and Blastocystis hominis. The incidence, in episodes per 100 person-years, was highest for B. hominis (65), followed by Entamoeba coli (31), Cryptosporidium parvum (17), and Entamoeba hartmanni (17). The PCVs' B. hominis episodes lasted 6,809 person-days (28.7% of the 23,689 person-days in the study), the E. coli episodes lasted 2,055 person-days (8.7%), and each of the other types of episodes lasted <2% of the person-days in the study. Gastrointestinal symptoms were somewhat more common and more persistent, but not significantly so, in association with pathogen episodes than with B. hominis and nonpathogen episodes. Although infections with pathogenic parasites could account for only a minority of the PCVs' diarrheal episodes, the continued acquisition of parasitic infections throughout the PCVs' >2-year stay in Guatemala suggests that PCVs repeatedly had fecal exposures and thus were at risk for infections with both parasitic and nonparasitic pathogens throughout their overseas service.

Cyclospora cayetanensis: a review, focusing on the outbreaks of cyclosporiasis in the 1990s

Cyclospora cayetanensis, a coccidian parasite that causes protracted, relapsing gastroenteritis, has a short recorded history. In retrospect, the first 3 documented human cases of Cyclospora infection were diagnosed in 1977 and 1978. However, not much was published about the organism until the 1990s. One of the surprises has been the fact that a parasite that likely requires days to weeks outside the host to become infectious has repeatedly caused foodborne outbreaks, including large multistate outbreaks in the United States and Canada. In this review, I discuss what has been learned about this enigmatic parasite since its discovery and what some of the remaining questions are. My focus is the foodborne and waterborne outbreaks of cyclosporiasis that were documented from 1990 through 1999. The occurrence of the outbreaks highlights the need for health care personnel to consider that seemingly isolated cases of infection could be part of widespread outbreaks and should be reported to public health officials. Health care personnel should also be aware that stool specimens examined for ova and parasites usually are not examined for Cyclospora unless such testing is specifically requested and that Cyclospora infection is treatable with trimethoprim-sulfamethoxazole.

A multiyear prospective study of the risk factors for and incidence of diarrheal illness in a cohort of Peace Corps volunteers in Guatemala

BACKGROUND

Diarrheal illness is the most common medical disorder among travelers from developed to developing countries and is common among expatriate residents in developing countries.

OBJECTIVE

To assess the risk factors for and incidence of diarrheal illness among Americans living in a developing country.

DESIGN

Prospective longitudinal study.

SETTING

Rural Guatemala.

PATIENTS

Cohort of 36 Peace Corps volunteers.

MEASUREMENTS

Collection of daily dietary and symptom data for more than 2 years; identification by multivariate Poisson regression analyses of risk factors for clinically defined episodes of diarrheal illness.

RESULTS

The 36 Peace Corps volunteers in this study had 307 diarrheal episodes (median, 7 per person), which lasted a median of 4 days (range, 1 to 112) and a total of 10.1% of the 23 689 person-days in the study. The incidence density (episodes per person-year) was 4.7 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. Statistically significant risk factors for diarrheal illness included drinking water whose source (for example, the tap) and, therefore, quality, was unknown to the person; eating food prepared by a Guatemalan friend or family; eating food at a small, working-class restaurant; eating fruit peeled by someone other than a Peace Corps volunteer; drinking an iced beverage; and eating ice cream, ice milk, or flavored ices. The relative risks comparing the presence of these exposures during the first 6-month period overseas with their absence during the second year of residence ranged from 1.90 to 2.67, and the summary attributable risk percentage (that is, the percentage of diarrheal episodes that could be ascribed to the exposures) was 75.4%. Exposures generally were riskier if they occurred during travel elsewhere in Guatemala rather than in the person's usual work area.

CONCLUSIONS

Diarrheal illness of mild-to-moderate severity continued to occur throughout Peace Corps service but decreased in incidence as length of stay increased. Various dietary behaviors increased the risk for diarrheal illness, which suggests that avoidance of potentially risky foods and beverages is beneficial.

Use of polymerase chain reaction to diagnose the fifth reported US case of autochthonous transmission of Trypanosoma cruzi, in Tennessee, 1998

In July 1998, the mother of an 18-month-old boy in rural Tennessee found a triatomine bug in his crib, which she saved because it resembled a bug shown on a television program about insects that prey on mammals. The gut contents of the Triatoma sanguisuga were found, by light microscopy and polymerase chain reaction (PCR), to be infected with Trypanosoma cruzi; PCR products hybridized with T. cruzi-specific oligonucleotide probes. Whole-blood specimens obtained from the child in July and August were negative by buffy-coat examination and hemoculture but positive by PCR and DNA hybridization, suggesting that he had low-level parasitemia. Specimens obtained after treatment with benznidazole were negative. He did not develop anti-T. cruzi antibody; 19 relatives and neighbors also were seronegative. Two of 3 raccoons trapped in the vicinity had positive hemocultures for T. cruzi. The child's case of T. cruzi infection-the fifth reported US autochthonous case-would have been missed without his mother's attentiveness and the availability of sensitive molecular techniques.

Leishmaniasis

In 1903, Leishman and Donovan separately described the protozoan now called Leishmania donovani in splenic tissue from patients in India with the life-threatening disease now called visceral leishmaniasis. Almost a century later, many features of leishmaniasis and its major syndromes (ie, visceral, cutaneous, and mucosal) have remained the same; but also much has changed. As before, epidemics of this sandfly-borne disease occur periodically in India and elsewhere; but leishmaniasis has also emerged in new regions and settings, for example, as an AIDS-associated opportunistic infection. Diagnosis still typically relies on classic microbiological methods, but molecular-based approaches are being tested. Pentavalent antimony compounds have been the mainstay of antileishmanial therapy for half a century, but lipid formulations of amphotericin B (though expensive and administered parenterally) represent a major advance for treating visceral leishmaniasis. A pressing need is for the technological advances in the understanding of the immune response to leishmania and the pathogenesis of leishmaniasis to be translated into field-applicable and affordable methods for diagnosis, treatment, and prevention of this disease.

A cluster of transfusion-associated babesiosis cases traced to a single asymptomatic donor

CONTEXT

The risk of acquiring babesiosis by blood transfusion is largely unknown since in areas where it is endemic it is often an asymptomatic infection.

OBJECTIVE

To investigate and treat a cluster of blood transfusion-associated babesiosis cases.

DESIGN

Case series and epidemiologic investigation.

SETTING

Urban inner-city hospital.

PATIENTS

Six persons who received Babesia microti-infected blood components from a donor.

MAIN OUTCOME MEASURE

Diagnosis and successful therapy of babesiosis following transfusion.

RESULTS

Six individuals (1 adult, 1 child, and 4 neonates) were exposed to products from a single blood donation by an asymptomatic Babesia-infected donor. Three of the 6 exposed patients became parasitemic. Polymerase chain reaction testing, animal inoculation studies, and indirect immunofluorescent antibody testing were used to confirm the presence of Babesia microti in the donor's blood and to establish the presence of infection in 3 of the 6 recipients. The 3 infected recipients and 1 additional recipient were treated without incident.

CONCLUSION

Physicians should consider babesiosis in the differential diagnosis of a febrile hemolytic disorder after blood transfusion. Prompt diagnosis is important since babesiosis is responsive to antibiotic therapy and, untreated, can be a fatal disease in certain risk groups.

The return of Cyclospora in 1997: another outbreak of cyclosporiasis in North America associated with imported raspberries. Cyclospora Working Group

BACKGROUND

In the spring of 1996, an outbreak of cyclosporiasis associated with fresh Guatemalan raspberries occurred in the United States and Canada. Another multistate outbreak of cyclosporiasis occurred in North America in the spring of 1997.

OBJECTIVE

To identify the vehicle of the outbreak that occurred in the spring of 1997.

DESIGN

Retrospective cohort studies of clusters of cases associated with events (such as banquets) and traceback investigations of sources of implicated produce.

SETTING

United States and Canada.

PATIENTS

Persons who attended events associated with clusters of cases of cyclosporiasis.

MEASUREMENTS

Identification of clinically defined or laboratory-confirmed cases of cyclosporiasis and risk factors for infection.

RESULTS

41 clusters of cases were reported in association with events held from 1 April through 26 May in 13 U.S. states, the District of Columbia, and 1 Canadian province. The clusters comprised 762 cases of cyclosporiasis, 192 (25.2%) of which were laboratory confirmed. In addition, 250 laboratory-confirmed sporadic cases were reported in persons who developed gastrointestinal symptoms from April through 15 June, for a total of 1012 cases. Fresh raspberries were the only food common to all 41 events and were the only type of berry served at 9 events (22.0%). Statistically significant associations between consumption of raspberry-containing items and cyclosporiasis were documented for 15 events (40.5% of 37). For 31 of the 33 events with well-documented traceback data, the raspberries either definitely came from Guatemala (8 events) or could have come from Guatemala (23 events). The mode of contamination of the raspberries remains unknown. The outbreak ended shortly after the exportation of fresh raspberries from Guatemala was voluntarily suspended at the end of May 1997.

CONCLUSIONS

Similar multistate, multicluster outbreaks of cyclosporiasis associated with consumption of Guatemalan raspberries have occurred in consecutive years. These outbreaks highlight the need for better understanding of the biology and epidemiology of Cyclospora cayetanensis and for stronger prevention and control measures to ensure the safety of produce eaten raw.

Epidemiologic studies of Cyclospora cayetanensis in Guatemala

In 1996 and 1997, cyclosporiasis outbreaks in North America were linked to eating Guatemalan raspberries. We conducted a study in health-care facilities and among raspberry farm workers, as well as a case-control study, to assess risk factors for the disease in Guatemala. From April 6, 1997, to March 19, 1998, 126 (2.3%) of 5, 552 surveillance specimens tested positive for Cyclospora; prevalence peaked in June (6.7%). Infection was most common among children 1.5 to 9 years old and among persons with gastroenteritis. Among 182 raspberry farm workers and family members monitored from April 6 to May 29, six had Cyclospora infection. In the case-control analysis, 62 (91%) of 68 persons with Cyclospora infection reported drinking untreated water in the 2 weeks before illness, compared with 88 (73%) of 120 controls (odds ratio [OR] 3.8, 95% confidence interval [CI] 1.4, 10.8 by univariate analysis). Other risk factors included water source, type of sewage drainage, ownership of chickens or other fowl, and contact with soil (among children younger than 2 years).

Surveillance for waterborne-disease outbreaks--United States, 1995-1996

PROBLEM/CONDITION

Since 1971, CDC and the U.S. Environmental Protection Agency have maintained a collaborative surveillance system for collecting and periodically reporting data that relate to occurrences and causes of waterborne-disease outbreaks (WBDOs).

REPORTING PERIOD COVERED

This summary includes data for January 1995 through December 1996 and previously unreported outbreaks in 1994.

DESCRIPTION OF THE SYSTEM

The surveillance system includes data about outbreaks associated with drinking water and recreational water. State, territorial, and local public health departments are primarily responsible for detecting and investigating WBDOs and for voluntarily reporting them to CDC on a standard form.

RESULTS

For the period 1995-1996, 13 states reported a total of 22 outbreaks associated with drinking water. These outbreaks caused an estimated total of 2,567 persons to become ill. No deaths were reported. The microbe or chemical that caused the outbreak was identified for 14 (63.6%) of the 22 outbreaks. Giardia lamblia and Shigella sonnei each caused two (9.1%) of the 22 outbreaks; Escherichia coli O157:H7, Plesiomonas shigelloides, and a small round structured virus were implicated for one outbreak (4.5%) each. One of the two outbreaks of giardiasis involved the largest number of cases, with an estimated 1,449 ill persons. Seven outbreaks (31.8% of 22) of chemical poisoning, which involved a total of 90 persons, were reported. Copper and nitrite were associated with two outbreaks (9.1% of 22) each and sodium hydroxide, chlorine, and concentrated liquid soap with one outbreak (4.5%) each. Eleven (50.0%) of the 22 outbreaks were linked to well water, eight in noncommunity and three in community systems. Only three of the 10 outbreaks associated with community water systems were caused by problems at water treatment plants; the other seven resulted from problems in the water distribution systems and plumbing of individual facilities (e.g., a restaurant). Six of the seven outbreaks were associated with chemical contamination of the drinking water; the seventh outbreak was attributed to a small round structured virus. Four of the seven outbreaks occurred because of backflow or backsiphonage through a cross-connection, and two occurred because of high levels of copper that leached into water after the installation of new plumbing. For three of the four outbreaks caused by contamination from a cross-connection, an improperly installed vacuum breaker or a faulty backflow prevention device was identified; no protection against backsiphonage was found for the fourth outbreak. Thirty-seven outbreaks from 17 states were attributed to recreational water exposure and affected an estimated 9,129 persons, including 8,449 persons in two large outbreaks of cryptosporidiosis. Twenty-two (59.5%) of these 37 were outbreaks of gastroenteritis; nine (24.3%) were outbreaks of dermatitis; and six (16.2%) were single cases of primary amebic meningoencephalitis caused by Naegleria fowleri, all of which were fatal. The etiologic agent was identified for 33 (89.2%) of the 37 outbreaks. Six (27.3%) of the 22 outbreaks of gastroenteritis were caused by Cryptosporidium parvum and six (27.3%) by E. coli O157:H7. All of the latter were associated with unchlorinated water (i.e., in lakes) or inadequately chlorinated water (i.e., in a pool). Thirteen (59.1%) of these 22 outbreaks were associated with lake water, eight (36.4%) with swimming or wading pools, and one(4.5%) with a hot spring. Of the nine outbreaks of dermatitis, seven (77.8%) were outbreaks of Pseudomonas dermatitis associated with hot tubs, and two (22.2%) were lake-associated outbreaks of swimmer's itch caused by Schistosoma species.

INTERPRETATION

WBDOs caused by E. coli O157:H7 were reported more frequently than in previous years and were associated primarily with recreational lake water. This finding suggests the need for better monitoring of water quality and identification of sources of

Chronic multisymptom illness affecting Air Force veterans of the Gulf War

CONTEXT

Gulf War (GW) veterans report nonspecific symptoms significantly more often than their nondeployed peers. However, no specific disorder has been identified, and the etiologic basis and clinical significance of their symptoms remain unclear.

OBJECTIVES

To organize symptoms reported by US Air Force GW veterans into a case definition, to characterize clinical features, and to evaluate risk factors.

DESIGN

Cross-sectional population survey of individual characteristics and symptoms and clinical evaluation (including a structured interview, the Medical Outcomes Study Short Form 36, psychiatric screening, physical examination, clinical laboratory tests, and serologic assays for antibodies against viruses, rickettsia, parasites, and bacteria) conducted in 1995.

PARTICIPANTS AND SETTING

The cross-sectional questionnaire survey included 3723 currently active volunteers, irrespective of health status or GW participation, from 4 air force populations. The cross-sectional clinical evaluation included 158 GW veterans from one unit, irrespective of health status.

MAIN OUTCOME MEASURES

Symptom-based case definition; case prevalence rate for GW veterans and nondeployed personnel; clinical and laboratory findings among veterans who met the case definition.

RESULTS

We defined a case as having 1 or more chronic symptoms from at least 2 of 3 categories (fatigue, mood-cognition, and musculoskeletal). The prevalence of mild-to-moderate and severe cases was 39% and 6%, respectively, among 1155 GW veterans compared with 14% and 0.7% among 2520 nondeployed personnel. Illness was not associated with time or place of deployment or with duties during the war. Fifty-nine clinically evaluated GW veterans (37%) were noncases, 86 (54%) mild-to-moderate cases, and 13 (8%) severe cases. Although no physical examination, laboratory, or serologic findings identified cases, veterans who met the case definition had significantly diminished functioning and well-being.

CONCLUSIONS

Among currently active members of 4 Air Force populations, a chronic multisymptom condition was significantly associated with deployment to the GW. The condition was not associated with specific GW exposures and also affected nondeployed personnel.

A foodborne outbreak of cyclosporiasis caused by imported raspberries

BACKGROUND

Cyclospora cayetanensis is a recently recognized parasite that causes prolonged diarrheal illness. Its modes of transmission have not been fully determined, although some investigations before 1996 implicated water. Outbreaks of cyclosporiasis in the United States in 1996 and 1997 are evidence of the increasing incidence of this disease. This report describes an outbreak of cyclosporiasis in persons who attended a luncheon on May 23, 1996, near Charleston, South Carolina.

METHODS

In this retrospective cohort study, we interviewed all 64 luncheon attendees and the chef regarding food and beverage exposures. A case of cyclosporiasis was defined as diarrhea (> or = 3 loose stools per day or > or = 2 loose stools per day if using antimotility drugs) after attending the luncheon. We identified sporadic cases of cyclosporiasis and traced the implicated food.

RESULTS

Of 64 luncheon attendees, 38 (59%) met the case definition. Persons who ate raspberries (relative risk [RR] = 5.4; 95% confidence interval [CI], 2.2-13.2) or potato salad (RR = 1.8; 95% CI, 1.2-2.6) were at significantly increased risk for illness. The population attributable risk percentages were 73% for raspberries and 20% for potato salad. Cyclospora oocysts were found in stools from 11 (85%) of the 13 case patients submitting specimens for testing. Implicated raspberries originated in Guatemala.

CONCLUSIONS

Our investigation is one of the first studies to implicate a specific food (raspberries) as a vehicle for transmission of Cyclospora. Because of the apparent increasing incidence of cyclosporiasis in the United States, family physicians should consider testing for Cyclospora in any patient with prolonged, unexplained diarrhea.

An outbreak of cyclosporiasis in Florida in 1995: a harbinger of multistate outbreaks in 1996 and 1997

Before 1995, only one outbreak of cyclosporiasis had been reported in the United States. To identify risk factors for Cyclospora infection acquired in Florida in 1995, we conducted a matched case-control study (24 sporadic cases and 69 controls) and retrospective cohort studies of clusters of cases associated with two May social events (attack rates = 15.4% [8 of 52] and 54.5% [6 of 11]). In univariate analysis of data from the case-control study, consumption of fresh raspberries (odds ratio [OR] = 6.0, 95% confidence interval [CI] = 1.1-31.7) and bare-handed contact with soil (OR = 5.4, 95% CI = 1.4-20.7) were associated with infection; soil contact was also implicated in multivariate analysis. For the events, mixed-fruit items that had only fresh raspberries and strawberries in common had elevated relative risks (3.7 and 4.2), but the confidence intervals overlapped 1.0. The raspberries eaten at the events and by sporadic case-patients were imported. Given the cumulative evidence of the three studies and the occurrence in 1996 and 1997 of outbreaks in North America associated with consumption of Guatemalan raspberries, food-borne transmission of Cyclospora was likely in 1995 in Florida as well.

Cyclospora

Although Cyclospora infection has been documented in humans worldwide since at least 1977, it is only in the past 2 years that this organism has come into prominence as a result of major foodborne outbreaks in the United States and Canada. Cyclospora causes significant gastrointestinal disease in immunocompetent and immunocompromised hosts and can be successfully treated with trimethoprim-sulfamethoxazole. The infection is under-recognized because our methods for diagnosis are rudimentary and insensitive. The mechanisms by which the parasite causes disease, the range of animal hosts, and the natural reservoir are unknown. Cyclospora is a unique coccidian parasite that has just begun to emerge; as yet, we have no clue as to where it comes from or where it hides.

First reported outbreak of abdominal angiostrongyliasis

Human abdominal angiostrongyliasis is a potentially fatal disease caused by Angiostrongylus costaricensis, a nematode found in the Americas. During the period of December 1994 through August 1995, an outbreak of this disease occurred in Guatemala. We identified 22 cases of abdominal angiostrongyliasis and conducted a matched case-control study to identify risk factors for illness. The median age of the 18 cases enrolled in the study was 37 years (range, 9-68 years), and 11 (61.1%) were male. Consumption of the following six raw food items was associated with angiostrongyliasis: mint (odds ratio [OR], 6.9; 95% confidence interval [CI], 1.5-66.0), shrimp (OR, infinite; 95% CI, 1.4 to infinite), and four kinds of ceviche that reportedly contained raw mint (OR for consumption of mint or ceviche that contained mint, 7.0; 95% CI, 1.0-315). We conclude that raw mint was the likely vehicle of infection for this outbreak. To our knowledge, this is the first reported outbreak of abdominal angiostrongyliasis and the first time that a specific food item has been epidemiologically linked to the disease.

First reported outbreak in the United States of cryptosporidiosis associated with a recreational lake

In the summer of 1994, an outbreak of cryptosporidiosis occurred among visitors to a state park in New Jersey. We enrolled 185 persons in a cohort study, 38 (20.5%) of whom had laboratory-confirmed cryptosporidiosis or gastrointestinal illness that met our clinical case definition. Having any exposure to lake water (e.g., swimming) was strongly associated with illness (P < .001). The outbreak lasted 4 weeks and affected an estimated 2,070 persons. The most likely sources of the outbreak were contaminated runoff of rainwater and infected bathers. This outbreak of cryptosporidiosis is the first reported to be associated with recreational exposure to lake water. Our investigation shows that even a large and ongoing outbreak may not be detected for several weeks. Health professionals and persons at high risk for severe cryptosporidiosis should be aware that recreational water can be a source of cryptosporidium infection.

An outbreak in 1996 of cyclosporiasis associated with imported raspberries. The Cyclospora Working Group

BACKGROUND

Cyclospora cayetanensis is a parasite that causes gastroenteritis. Until last year most of the documented cases of cyclosporiasis in North America were in overseas travelers. In 1996, a large outbreak of cyclosporiasis occurred in North America. We investigated this outbreak.

METHODS

Health departments solicited information from clinicians and laboratories on cases of cyclosporiasis, which were then reported to the Centers for Disease Control and Prevention and to Health Canada. We conducted retrospective cohort studies for the cases associated with events (e.g., luncheons) and attempted to identify the sources of the implicated food.

RESULTS

A total of 1465 cases of cyclosporiasis were reported by 20 states, the District of Columbia, and 2 provinces. Of these cases, 978 (66.8 percent) were laboratory confirmed and 725 (49.5 percent) were associated with 55 events that were held from May 3 through June 14. Raspberries were definitely served at 50 events and may have been served at 4 events. For 27 of the 41 events for which adequate data were available (65.8 percent), the associations between the consumption of berries (raspberries with or without other berries) and cyclosporiasis were statistically significant (P<0.05). For all 29 events for which there were good data, the raspberries definitely came from Guatemala (21 events, 72.4 percent) or may have come from Guatemala (8 events, 27.6 percent). As few as five Guatemalan farms could have accounted for the 25 events for which the raspberries could be traced to a single exporter per event. The mode of contamination of the raspberries remains unclear.

CONCLUSIONS

This large outbreak of cyclosporiasis in North America in 1996 was associated with the consumption of Guatemalan raspberries. The outbreak illustrates the need to consider that a local cluster of foodborne illness may be part of a widespread outbreak and to pursue investigations to the source of the implicated vehicle.

Transfusion-transmitted babesiosis in Washington State: first reported case caused by a WA1-type parasite

Most cases of babesiosis reported in the United States have been tickborne and caused by Babesia microti, the etiologic agent of all previously described transfusion-transmitted cases. A 76-year-old man with the first recognized case of transfusion-transmitted infection with the recently identified WA1-type Babesia parasite is described. The subject received multiple blood transfusions in 1994. Indirect immunofluorescent antibody testing of serum from 57 blood donors implicated a 34-year-old man (WA1 titer, 1:65,536) whose donation had been used for packed red cells. Isolates of the organisms that infected the recipient and the donor, both of whom were spleen-intact residents of Washington State, were obtained by hamster inoculation. The DNA sequence of a 536-bp region of the nuclear small subunit-rRNA gene of both isolates was identical to that of WA1 (isolated in 1991 from the index WA1 case-patient). Effective measures for preventing transmission of babesiosis by blood transfusion are needed.

Reevaluating the molecular taxonomy: is human-associated Cyclospora a mammalian Eimeria species?

Human-associated Cyclospora is a coccidian parasite that causes diarrheal disease. A reevaluation of the parasite's molecular taxonomy that takes into account newly published data for seven Eimeria species shows that Cyclospora belongs to the Eimeria clade (Eimeriidae family). The Cyclospora branch on the phylogenetic tree is between the branches of the eight avian and two mammalian Eimeria species that have been evaluated to date. Furthermore, preliminary results indicate that Cyclospora and Isospora belli, another coccidian parasite that causes diarrheal disease in humans, belong to different families. To improve our understanding of the taxonomy of human-associated Cyclospora, molecular evaluation of isolates of additional Cyclospora and Eimeria species is needed.

Cryptosporidiosis in Washington State: an outbreak associated with well water

In 1994, an outbreak of cryptosporidiosis occurred in a rural community in Washington State where water was supplied by two deep unchlorinated wells. Confirmed case-patients had a stool specimen containing Cryptosporidium parvum oocysts. Probable case-patients had diarrhea lasting > or = 5 days. Sixty-two households (68.1% of 91) responded to a survey. Eighty-six cases (15 confirmed, 71 probable) were identified, for an attack rate of 50.9% (86/169 residents). Drinking unboiled well water was associated with being a case-patient (relative risk, 1.84; 95% confidence interval, 0.89-3.82), and a significant dose-response relationship was found between water consumption and illness (P = .004). Water that was presumed to be treated wastewater from a piped irrigation system was found dripping along one well's outer casing, which was extensively rusted. Presumptive Cryptosporidium oocysts were found in well water and in treated wastewater. This investigation demonstrates that even underground water systems are vulnerable to contamination.

Surveillance for waterborne-disease outbreaks--United States, 1993-1994

PROBLEM/CONDITION

Since 1971, CDC and the U.S. Environmental Protection Agency have maintained a collaborative surveillance system for collecting and periodically reporting data that relate to occurrences and causes of waterborne-disease outbreaks (WBDOs).

REPORTING PERIOD COVERED

This summary includes data for January 1993 through December 1994 and for previously unreported outbreaks in 1992.

DESCRIPTION OF THE SYSTEM

The surveillance system includes data about outbreaks associated with water intended for drinking (i.e., drinking water) and those associated with recreational water. State, territorial, and local public health departments are primarily responsible for detecting and investigating WBDOs and voluntarily reporting them to CDC on a standard form.

RESULTS

For the 2-year period 1993-1994, 17 states and one territory reported a total of 30 outbreaks associated with drinking water. These outbreaks caused an estimated 405,366 persons to become ill, including 403,000 from an outbreak of cryptosporidiosis in Milwaukee, the largest WBDO ever documented in the United States, and 2,366 from the other 29 outbreaks. No etiologic agent was identified for five (16.7%) of the 30 outbreaks. The protozoan parasites Giardia lamblia and Cryptosporidium parvum caused 10 (40.0%) of the 25 outbreaks for which the etiologic agent was identified. Two outbreaks of cryptosporidiosis occurred in large metropolitan areas (i.e., Milwaukee and Las Vegas/Clark County) and were associated with deaths among immunocompromised persons. The waterborne nature of these two outbreaks was not recognized until at least 2 weeks after the onset of the Milwaukee outbreak and until after the end of the Las Vegas outbreak. Campylobacter jejuni was implicated for three outbreaks and the following pathogens for one outbreak each: Shigella sonnei, Shigella flexneri, non-O1 Vibrio cholerae (in a U.S. territory; the vehicle was commercially bottled water), and Salmonella serotype Typhimurium (the outbreak was associated with seven deaths). Eight outbreaks of chemical poisoning were reported: three were caused by lead (one case each), two by fluoride, two by nitrate and one by copper. Twenty (66.7%) of the 30 outbreaks were associated with a well-water source. Fourteen states reported a total of 26 outbreaks associated with recreational water, in which an estimated 1,714 persons became ill. Fourteen (53.8%) of these 26 were outbreaks of gastroenteritis. The etiologic agent in each of these 14 outbreaks was identified; 10 (71.4%) were caused by G. lamblia or C. parvum. Six of these 10 were associated with chlorinated, filtered pool water, and three with lake water. One of the latter was the first reported outbreak of cryptosporidiosis associated with the recreational use of lake water. Four outbreaks of lake water-associated bacterial gastroenteritis were reported, two caused by S. sonnei, one by S. flexneri, and one by Escherichia coli O157:H7. Nine outbreaks of hot tub- whirlpool-, or swimming pool-associated pseudomonas dermatitis were reported. Two outbreaks of swimming pool-associated dermatitis had a suspected chemical etiology. The child who had the one reported case of primary amebic meningoencephalitis, caused by infection with Naegleria fowleri, died.

INTERPRETATION

The number of WBDOs reported annually has been similar for each year during 1987-1994, except for an increase in 1992. Protozoan parasites, especially C. parvum and G. lamblia, remain important etiologic agents of WBDOs. The outbreaks of cryptosporidiosis in Milwaukee and Las Vegas demonstrate that WBDOs can occur in large metropolitan areas. Surveillance methods are needed that expedite the detection of WBDOs and the institution of preventive measures (e.g., boil-water advisories).

ACTIONS TAKEN

Surveillance data that identify the types of water systems, their deficiencies, and the etiologic agents associated with outbreaks are used to evaluate the adequacy of current technologies for prov

Epidemic visceral leishmaniasis in southern Sudan: treatment of severely debilitated patients under wartime conditions and with limited resources

OBJECTIVES

1) To determine the proportions of patients with visceral leishmaniasis who had various treatment outcomes when cared for under wartime conditions and with limited resources and 2) to identify patient characteristics associated with the outcomes.

DESIGN

Cohort study.

SETTING

Médecins sans Frontières-Holland's treatment center in Duar, Western Upper Nile Province, an area in southern Sudan that has been severely affected by Sudan's civil war and a massive epidemic of visceral leishmaniasis.

PATIENTS

3076 consecutive patients who had visceral leishmaniasis, were admitted to the treatment center the first year the center was operational (August 1990 to July 1991), and were treated with the pentavalent antimonial compound sodium stibogluconate.

MEASUREMENTS

Patient characteristics on admission and four mutually exclusive treatment outcomes (default during first admission, death during first admission, discharge and readmission for retreatment [relapse], and discharge and no readmission for retreatment [successful treatment]).

RESULTS

The patients had a median age of 15 years and were notably anemic (median hemoglobin level, 77g/L) and malnourished (median body mass index of adults [> or = 18 years of age], 15.2 kg/m2); most (91.0%) had been sick less than 5 months. Although patients could not be monitored after treatment to document cure, most (2562 [83.3%]) were successfully treated; 336 (10.9%) died during their first admission, and 79 are known to have relapsed (3.0% of those discharged alive [that is, those whose final treatment outcome was successful treatment or relapse]). In univariable analysis, young and older age (<5 or > or = 45 years of age), long duration of illness (> or = 5 months), markedly low hemoglobin level or body mass index, large spleen, high parasite density, and vomiting at least once during the treatment course were associated with death. In multiple logistic regression analysis of data for a subgroup of 1207 adults (those who did not default or relapse and for whom data were recorded on age, sex, duration of illness, hemoglobin level, body mass index, and spleen size), the approximate risk ratios for death were 2.2 (95% Cl, 1.4 to 3.6) for those with a long duration of illness, 3.6 (Cl, 2.1 to 5.9) for those 45 years of age or older, 4.6 (Cl, 2.2 to 9.4) for those with a hemoglobin level less than 60 g/L, and 12.2 (Cl, 3.2 to 47.2) for those with a body mass index less than 12.2 kg/m2. CONCLUSION; Despite the severe debility of the patients and the exceptionally difficult circumstances under which they were treated, most fared remarkably well.

Cryptosporidiosis: an outbreak associated with drinking water despite state-of-the-art water treatment

OBJECTIVE

To determine the magnitude and source of an outbreak of cryptosporidiosis among persons with human immunodeficiency virus (HIV) infection and to determine whether the outbreak extended into the immunocompetent population.

DESIGN

Matched case-control study and environmental investigation.

SETTING

Clark County, Nevada.

PARTICIPANTS

Adults with HIV infection (36 case-patients with laboratory-confirmed Cryptosporidium parvum infection and 107 controls), matched by physician or clinic and by CD4+ cell count category.

MEASUREMENTS

Potential risk factors for infection, death rates, and data on water quality.

RESULTS

Review of surveillance and microbiology records identified 3 cases of cryptosporidiosis in 1992 (the first year that cryptosporidiosis was reportable in Nevada), 23 cases in 1993, and 78 cases in the first quarter of 1994. Of the 78 laboratory-confirmed cases in the first quarter of 1994, 61 (78.2%) were in HIV-infected adults. Of these 61 adults, 32 (52.5%) had died by 30 June 1994; at least 20 of the 32 (62.5%) had cryptosporidiosis listed on their death certificates. In the case-control study, persons who drank any unboiled tap water were four times more likely than persons who drank only bottled water to have had cryptosporidiosis (odds ratio, 4.22 [95% Cl, 1.22 to 14.65]; P = 0.02). For persons with CD4+ cell counts less than 100 cells/mm3, the association between tap water and cryptosporidiosis was even stronger (odds ratio, 13.52 [Cl, 1.78 to 102.92]; P = 0.01). Additional data indicate that this outbreak also affected persons who were not infected with HIV. No elevated turbidity values or coliform counts and no Cryptosporidium oocysts were found in testing of source (Lake Mead) or finished (treated) water during the study period, but so-called presumptive oocysts were intermittently found after the investigation in samples of source water, filter backwash, and finished water.

CONCLUSIONS

A cryptosporidiosis outbreak was associated with municipal drinking water, despite state-of-the-art water treatment and water quality better than that required by current federal standards. This outbreak highlights the importance of surveillance for cryptosporidiosis and the need for guidelines for the prevention of water-borne-Cryptosporidium infection among HIV-infected persons.

Babesiosis in Wisconsin: a potentially fatal disease

Babesiosis is emerging as an important tick-borne zoonosis in the United States. Most reported cases of this parasitic disease have been acquired in the Northeast. To date, only two clinical cases of Babesia microti infection acquired in the upper Midwest have been described. We report eight more cases. Most if not all of the 10 total cases probably were acquired in northwestern Wisconsin. Three cases (30% of 10) we now report were fatal and occurred in elderly patients (65-75 years old) who died after complicated hospital courses. One patient probably had had a latent Babesia infection that activated because of immunosuppression attributable to high-dose corticosteroid therapy and to splenic infarctions caused by cholesterol emboli. All three fatal cases were diagnosed incidentally and highlight the importance of considering the diagnosis of babesiosis in febrile patients who have been in babesiosis-endemic areas; examining their blood smears carefully; and treating promptly with clindamycin and quinine, and, if indicated, exchange transfusion. Medical personnel should be knowledgeable about this zoonosis, which is not limited to the northeastern United States, and is potentially serious, sometimes fatal.

Infection with a babesia-like organism in northern California

BACKGROUND

Human babesiosis is a tick-transmitted zoonosis associated with two protozoa of the family Piroplasmorida: Babesia microti (in the United States) and B. divergens (in Europe). Recently, infection with an unusual babesia-like piroplasm (designated WA1) was described in a patient from Washington State. We studied four patients in California who were identified as being infected with a similar protozoal parasite. All four patients had undergone splenectomy, three because of trauma and one because of Hodgkin's disease. Two of the patients had complicated courses, and one died.

METHODS

Piroplasm-specific nuclear small-subunit ribosomal DNA was recovered from the blood of the four patients by amplification with the polymerase chain reaction. The genetic sequences were compared with those of other known piroplasm species. Indirect immunofluorescent-antibody testing of serum from the four patients and from other potentially exposed persons was performed with WA1 and babesia antigens.

RESULTS

Genetic sequence analysis showed that the organisms from all four patients were nearly identical. Phylogenic analysis showed that this strain is more closely related to a known canine pathogen (B. gibsoni) and to theileria species than to some members of the genus babesia. Serum from three of the patients was reactive to WA1 but not to B. microti antigen. Serologic testing showed WA1-antibody seroprevalence rates of 16 percent (8 of 51 persons at risk) and 3.5 percent (4 of 115) in two geographically distinct areas of northern California.

CONCLUSIONS

A newly identified babesia-like organism causes infections in humans in the western United States. The clinical spectrum associated with infection with this protozoan ranges from asymptomatic infection or influenza-like illness to fulminant, fatal disease.

Persistence of Schistosoma haematobium infection despite multiple courses of therapy with praziquantel

A 7-year-old boy, who had returned to the United States in June 1991 after a 3-year stay in Malawi, was evaluated in October 1991 because of hematuria. He was excreting Schistosoma haematobium eggs and was treated with praziquantel (PZQ; approximately 40 mg/kg). He may have spit up < or = 30% of this dose, and a concomitant Giardia lamblia infection might have caused malabsorption of PZQ. Because of persistent excretion of viable eggs, he was retreated with PZQ in January and May 1992. Egg excretion was first quantified 2 months following his second course of PZQ; at that time it was 35 eggs per 10 mL of urine. He excreted viable eggs at least as late as October 1992, 5 months after his third PZQ course. Experimental administration of chemotherapy to hamsters infected with the S. haematobium strain demonstrated that it was susceptible to PZQ. Repeated courses of therapy with PZQ may be necessary to cure S. haematobium infection, and both parasite and host factors should be considered if infection persists.

Infections with intestinal parasites in Peace Corps volunteers in Guatemala

To assess the role of parasites in causing diarrhea in Peace Corps volunteers in Guatemala, 115 stool specimens from a case-control investigation (48 case [diarrhea] and 26 control episodes) were examined. A potentially pathogenic protozoan that could account for diarrheal illness was found for only 12% of the case episodes.

Cultivation and phylogenetic characterization of a newly recognized human pathogenic protozoan

An intraerythrocytic protozoan (WA1) recently isolated from a patient in Washington State was shown to be morphologically identical to Babesia microti but biologically and genetically distinct. Continuous growth of WA1 was established in stationary erythrocyte cultures. Hybridization of a chemiluminescent Babesia-specific DNA probe to Southern blots of restriction enzyme-digested genomic DNA showed that WA1 could be distinguished from other Babesia species that were antigenically cross-reactive (Babesia gibsoni and babesial parasites from desert bighorn sheep, Ovis canadensis nelsoni) or known to infect humans (B. microti, Babesia divergens, and Babesia equi), or both. A 1436-bp portion of the nuclear small subunit rRNA gene of WA1 was sequenced and analyzed. Genetic distance analysis showed that WA1 is most closely related to the canine pathogen B. gibsoni and lies within a phylogenetic cluster with Theileria species and B. equi. The methodology described will be useful for improved diagnosis and identification of human protozoal pathogens.

Characterization of a variant strain of Norwalk virus from a food-borne outbreak of gastroenteritis on a cruise ship in Hawaii

A gastroenteritis outbreak affecting at least 217 (41%) of 527 passengers on a cruise ship was caused by a variant strain of Norwalk virus (NV) that is related to but distinct from the prototype NV strain. Consumption of fresh-cut fruit served at two buffets was significantly associated with illness (P < or = 0.01), and a significant dose-response relationship was evident between illness and the number of various fresh-cut fruit items eaten. Seven (58%) of 12 paired serum specimens from ill persons demonstrated at least fourfold rises in antibody response to recombinant NV capsid antigen. A 32-nm small round-structured virus was visualized by electron microscopy in 4 (29%) of 14 fecal specimens, but none of the 8 specimens that were examined by an enzyme immunoassay for NV antigen demonstrated antigen. Four (40%) of 10 fecal specimens were positive by reverse transcriptase-PCR by using primer pairs selected from the polymerase region of NV. In a 145-bp region, the PCR product shared only 72% nucleotide sequence identity with the reference NV strain and 77% nucleotide sequence identity with Southampton virus but shared 95% nucleotide sequence identity with UK2 virus, a United Kingdom reference virus strain. In addition, the outbreak virus was serotyped as UK2 virus by solid-phase immune electron microscopy. The genetic and antigenic divergence of the outbreak strain from the reference NV strain highlights the need for more broadly reactive diagnostic assays and for improved understanding of the relatedness of the NV group of agents.

Surveillance for waterborne disease outbreaks--United States, 1991-1992

PROBLEM/CONDITION

Since 1971, CDC and the U.S. Environmental Protection Agency have maintained a collaborative surveillance program for collection and periodic reporting of data on the occurrence and causes of waterborne disease outbreaks.

REPORTING PERIOD COVERED

January 1991 through December 1992.

DESCRIPTION OF SYSTEM

The surveillance system includes data about outbreaks associated with water intended for drinking and also about those associated with recreational water. State and local public health departments are the agencies with primary responsibility for the detection and investigation of outbreaks. State and territorial health departments report these outbreaks to CDC on a standard form.

RESULTS

For the 2-year period 1991-1992, 17 states and territories reported 34 outbreaks associated with water intended for drinking. The outbreaks caused an estimated 17,464 persons to become ill. A protozoal parasite (Giardia lamblia or Cryptosporidium) was identified as the etiologic agent for seven of the 11 outbreaks for which an agent was determined. Five (71%) of the outbreaks caused by protozoa were associated with a surface-influenced groundwater source. One outbreak of cryptosporidiosis was associated with filtered and chlorinated surface water. Shigella sonnei and hepatitis A virus were implicated in one outbreak each; both were linked to consumption of contaminated well water. Two outbreaks due to acute chemical poisoning were reported; one had an associated fatality. No etiology was established for 23 (68%) of the 34 outbreaks, including the largest one reported during this period, in which an estimated 9,847 persons using a filtered surface water supply developed gastroenteritis. Most (76%) of the 34 outbreaks were associated with a well water source. Twenty-one states reported 39 outbreaks associated with recreational water, in which an estimated 1,825 persons became ill. The most frequently reported illness was hot tub- or whirlpool-associated Pseudomonas dermatitis (12 outbreaks). Of 11 outbreaks of swimming-associated gastroenteritis, six were caused by Giardia or Cryptosporidium, including three outbreaks associated with chlorinated, filtered pool water. The first reported outbreak of Escherichia coli O157:H7 infection associated with recreational exposure occurred during this period. Primary amebic meningoencephalitis, caused by Naegleria fowleri infection, resulted in six deaths.

INTERPRETATION

The number of waterborne disease outbreaks reported per year has not changed substantially in the past 5 years. However, etiologic agents only recently associated with waterborne disease, such as E. coli O157:H7 and Cryptosporidium, are being reported more frequently and from new settings. Water quality data for outbreaks during the period 1991-1992 indicate that available water disinfection technology is not always in place or used reliably.(ABSTRACT TRUNCATED AT 400 WORDS)

Babesiosis in Washington State: a new species of Babesia?

OBJECTIVE

To characterize the etiologic agent (WA1) of the first reported case of babesiosis acquired in Washington State.

DESIGN

Case report, and serologic, molecular, and epizootiologic studies.

SETTING

South-central Washington State.

PATIENT

A 41-year-old immunocompetent man with an intact spleen who developed a moderately severe case of babesiosis.

MEASUREMENTS

Serum specimens from the patient were assayed by indirect immunofluorescent antibody (IFA) testing for reactivity with seven Babesia species and with WA1, which was propagated in hamsters inoculated with his blood. A Babesia-specific, ribosomal-DNA (rDNA) probe was hybridized to Southern blots of restriction-endonuclease-digested preparations of DNA from WA1, Babesia microti, and Babesia gibsoni. Serum specimens from 83 family members and neighbors were assayed for IFA reactivity with WA1 and B. microti. Small mammals and ticks were examined for Babesia infection.

RESULTS

The patient's serum had very strong IFA reactivity with WA1, strong reactivity with B. gibsoni (which infects dogs), but only weak reactivity with B. microti. DNA hybridization patterns with the rDNA probe clearly differentiated WA1 from B. gibsoni and B. microti. Four of the patient's neighbors had IFA titers to WA1 of 256. The tick vector and animal reservoir of WA1 have not yet been identified, despite trapping 83 mammals and collecting 235 ticks.

CONCLUSIONS

WA1 is morphologically indistinguishable but antigenically and genotypically distinct from B. microti. Some patients elsewhere who were assumed to have been infected with B. microti may have been infected with WA1. Improved serodiagnostic and molecular techniques are needed for characterizing Babesia species and elucidating the epidemiology of babesiosis, an emergent zoonosis.

American cutaneous leishmaniasis in U.S. travelers

OBJECTIVE

To characterize the exposures and practices of U.S. travelers who acquired cutaneous leishmaniasis in the Americas and to highlight problems they encountered in seeking medical care from U.S. physicians.

DESIGN

A retrospective review of Centers for Disease Control and Prevention Drug Service records and a telephone survey of patients.

PATIENTS

Fifty-nine civilian U.S. travelers with American cutaneous leishmaniasis for whom the Drug Service released sodium stibogluconate between 1 January 1985 and 30 April 1990; 58 travelers (98%) were interviewed.

MAIN MEASUREMENTS

Travel destination, exposure duration, knowledge about leishmaniasis, and time from noticing skin lesions to release of drug.

RESULTS

Overall, travelers acquired leishmaniasis in as many as 14 countries; 33 of 59 travelers (56%) were infected in Mexico or Central America. Twenty-seven travelers (46%) were conducting field studies and 23 (39%) were tourists, visitors, or tour guides. At least 15 persons (26% of the 58 interviewed travelers) were in forested areas for 1 week or less; at least 6 of these persons had a maximum exposure of 2 days. Ten persons (17%) were home at least 1 month before they noticed skin lesions. Patients consulted from one to seven physicians (mean, 2.1 physicians) before leishmaniasis was diagnosed. Overall, the median time from noticing lesions to the release of drug was 112 days (range, 13 to 1022 days); however, the median was only 55 days for 13 patients (22%) unusually knowledgeable about leishmaniasis and was a maximum of 60 days for 16 patients (28%) (including 7 of the 13 unusually knowledgeable patients) who generally consulted physicians exceptionally knowledgeable about infectious and tropical diseases.

CONCLUSIONS

Travelers to forested areas in Mexico and Central and South America and their physicians need to be educated about the risk for acquiring leishmaniasis even during short stays, as well as about effective preventive measures; and appropriate medical management [corrected].

Laboratory-acquired malaria, leishmaniasis, trypanosomiasis, and toxoplasmosis

Because of renewed interest in parasitic diseases, increasing numbers of persons in clinical and research laboratories have the potential for exposure to parasites and therefore are at risk for acquiring parasitic infections. In this review of laboratory-acquired parasitic infections, we concentrate on protozoan diseases that frequently have been reported to be laboratory acquired: malaria, leishmaniasis, trypanosomiasis (American and African), and toxoplasmosis. These diseases can be severe, even fatal, and may be difficult to diagnose. Many laboratorians who have acquired these diseases did not recall having had an accident. Of those with recognized accidents, needlestick injuries were the most common. Laboratories should have established protocols for handling specimens that may contain viable organisms and for responding to laboratory accidents.

Diloxanide furoate for treating asymptomatic Entamoeba histolytica cyst passers: 14 years' experience in the United States

Diloxanide furoate is used for treating asymptomatic or mildly symptomatic persons who are passing cysts of Entamoeba histolytica. The Centers for Disease Control (Atlanta) released this drug for 4,371 treatment courses from 1977 through 1990. Of the 2,815 report forms (64%) returned, 656 adverse effects were reported for 390 treatment courses (14%); they included flatulence (260), diarrhea or cramping (100), nausea (93), headache (17), disorientation or dizziness (9), and diplopia (4). During 1984-1990 uniform collection of data allowed more detailed analysis of toxicity and efficacy; fewer adverse effects were reported for persons aged 20 months to 10 years than for persons aged greater than 10 years (6 of 206 [3%] vs. 89 of 763 [12%], relative risk = 0.27, 95% confidence interval = 0.12 less than relative risk less than 0.61). Parasitological cures were achieved during 497 (86%) of the 575 treatment courses (52%) administered to asymptomatic persons who were passing cysts, who had received a full 10-day treatment course, and for whom results of a follow-up stool examination (greater than or equal to 14 days post-treatment) were available. Diloxanide furoate is safe and effective for treating asymptomatic persons who are passing E. histolytica cysts and may be particularly well tolerated in children.

Sodium stibogluconate (Pentostam) overdose during treatment of American cutaneous leishmaniasis

A 27-year-old woman who acquired cutaneous leishmaniasis in Central America was inadvertently treated with 10 times the intended daily dose of the pentavalent antimonial compound sodium stibogluconate (Pentostam): 8500 mg (143 mg/kg) instead of 850 mg. The patient felt "wiped out" during the 4-h infusion of the drug. After the mistake in dosing was discovered, she was vigorously hydrated and carefully monitored in an intensive care unit for greater than 48 h. Her vital signs were stable, and no arrhythmias were noted. Her alanine aminotransferase level rose briefly to 2.4 times the upper limit of normal, and her white blood cell count briefly fell 43% to a low of 3700/microliter. Her skin lesions subsequently healed without further therapy. Although sodium stibogluconate has been associated with a variety of side effects, in this case, a single high dose of the drug was tolerated without serious toxicity.

The natural history of cutaneous leishmaniasis in Guatemala

The natural history of American cutaneous leishmaniasis was studied in Guatemala by analyzing the characteristics of 355 untreated leishmanial lesions, observing the evolution of 57 lesions on persons who received a placebo in treatment trials, and analyzing data from a population-based survey concerning the duration of 82 untreated lesions. Of 25 lesions caused by Leishmania mexicana that were followed prospectively, 22 (88%) completely reepithelialized by a median lesion age of 14 weeks, and 17 (68%) were classified as cured (no residual wound inflammation or reactivation during at least 6 months of follow-up). In contrast, 7 (22%) of 32 lesions caused by Leishmania braziliensis reepithelialized by a median lesion age of 13 weeks, and only 2 (6%) cured. These data demonstrate that the species of Leishmania is the primary determinant of the clinical course and outcome of untreated lesions and underscore the need for field-applicable diagnostic techniques that provide rapid species identification.

Recommendations for treating leishmaniasis with sodium stibogluconate (Pentostam) and review of pertinent clinical studies

Pentavalent antimonial compounds have been the mainstay of the treatment of visceral, cutaneous, and mucosal leishmaniasis for approximately half a century. Pentostam (sodium stibogluconate) is the pentavalent antimonial compound available in the United States (through the Centers for Disease Control). As dosage regimens for treating leishmaniasis have evolved, the daily dose of antimony and the duration of therapy have been progressively increased to combat unresponsiveness to therapy. In the 1980s, the use of 20 mg/kg/day (instead of 10 mg/kg/day) of antimony was recommended, but only to a maximum daily dose of 850 mg. The authors have concluded on the basis of recent efficacy and toxicity data that this 850-mg restriction should be removed; the evidence to date, which is summarized here, suggests that a regimen of 20 mg/kg/day of pentavalent antimony, without an upper limit on the daily dose, is more efficacious and is not substantially more toxic than regimens with lower daily doses. We recommend treating all forms of leishmaniasis with a full 20 mg/kg/day of pentavalent antimony. We treat cutaneous leishmaniasis for 20 days and visceral and mucosal leishmaniasis for 28 days. Our judgment of cure is based on clinical criteria.

Energy dependence of chloroquine accumulation and chloroquine efflux in Plasmodium falciparum

Chloroquine inhibits the growth of susceptible malaria parasites at low (nanomolar) concentrations because of an energy-requiring drug-concentrating mechanism in the parasite secondary lysosome (food vacuole) which is dependent on the acidification of that vesicle. Chloroquine resistance results from another energy-requiring process: efflux of chloroquine from the resistant parasite with a half-time of 2 min. Chloroquine efflux is inhibited reversibly by the removal of metabolizable substrate (glucose); it is also reduced by the ATPase inhibitor vanadate. These results suggest that chloroquine efflux is an energy-requiring process dependent on the generation and hydrolysis of ATP. Chloroquine efflux cannot be explained by differences in drug accumulation between chloroquine-susceptible and -resistant parasites because the 40-50-fold difference in initial efflux rates between -susceptible and -resistant parasites is unchanged when both parasites contain the same amount of chloroquine. Although chloroquine efflux is phenotypically similar to the efflux of anticancer drugs from multidrug-resistant (mdr) mammalian cells, it is not linked to either of the mdr-like genes of the parasite.

Waterborne-disease outbreaks, 1989-1990

For the 2-year period 1989-1990, 16 states reported 26 outbreaks due to water intended for drinking; an estimated total of 4,288 persons became ill in these outbreaks. Giardia lamblia was implicated as the etiologic agent for seven of the 12 outbreaks in which an agent was identified. The outbreaks of giardiasis were all associated with ingestion of unfiltered surface water or surface-influenced groundwater. An outbreak with four deaths was attributed to Escherichia coli O157:H7, the only bacterial pathogen implicated in any of the outbreak investigations. An outbreak of remitting, relapsing diarrhea was associated with cyanobacteria (blue-green algae)-like bodies, whose role in causing diarrheal illness is being studied. Two outbreaks due to hepatitis A and one due to a Norwalk-like agent were associated with use of well water. Eighteen states reported a total of 30 outbreaks due to the use of recreational water, which resulted in illness for an estimated total of 1,062 persons. These 30 reports comprised 13 outbreaks of whirlpool- or hot tub-associated Pseudomonas folliculitis; 13 outbreaks of swimming-associated gastroenteritis, including five outbreaks of shigellosis; one outbreak of hepatitis A associated with a swimming pool; and three cases of primary amebic meningoencephalitis caused by Naegleria. The national surveillance of outbreaks of waterborne diseases, which has proceeded for 2 decades, continues to be a useful means for characterizing the epidemiology of waterborne diseases.

Accumulation of chloroquine by membrane preparations from Plasmodium falciparum

Chloroquine susceptibility and resistance have been associated respectively with the uptake and efflux of chloroquine by Plasmodium falciparum. We made membrane preparations from parasitized and unparasitized red cells in order to study chloroquine accumulation in a cell-free system. The accumulation of [3H]chloroquine by these preparations is inhibited by unlabeled chloroquine and thus is specific. Only membranes from parasitized red cells demonstrate time-dependent chloroquine accumulation; membranes from unparasitized red cells do not. Chloroquine accumulation is eliminated by detergent (0.05% Triton X-100) and reduced by a hypertonic medium, consistent with accumulation inside membrane vesicles rather than binding to membranes. Accumulation is energy dependent; it has a specific requirement for ATP, which cannot be replaced with GTP, CTP, UTP, TTP or ADP, an apparent Km of 21 microM and an apparent Vmax of 4.6 pmol (mg protein)-1 h-1. Vesicle acidification is MgATP dependent, and is reversed by NH4Cl. Chloroquine accumulation is inhibited by reduced medium pH, N-ethylmaleimide or oligomycin, but not by vanadate or ouabain. These studies demonstrate that membrane vesicles prepared from parasitized red cells provide a model system for the study of chloroquine accumulation by P. falciparum.

The M13 repeat probe detects RFLPs between two strains of the protozoan malaria parasite Plasmodium falciparum

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