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* Objective: To characterize the etiologic agent (WA1) of the first reported case of babesiosis acquired in Washington State. * Design: Case report, 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 lFA reactivity with WA1 and B. microti. Small mammals and ticks were examined for Babesia infection. * Results: The patient's serum had very strong lFA 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 lFA 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., A new species of Babesia may have been the cause of the first reported case of babesiosis in Washington State. Babesiosis is a group of tick-borne diseases caused by infection with protozoa of the genus Babesia. This new species of Babesia is referred to as WA1. A 41-year-old man from south-central Washington was diagnosed with babesiosis. Blood samples from the patient were analyzed for reactivity to seven different species of Babesia and WA1. Blood samples from the patient and 83 family members and neighbors were also tested for reactivity to B. microti and WA1. The patient had very strong reactivity to WA1, strong reactivity to B. gibsoni and weak reactivity to B. microti. WA1 was genetically distinct from B. gibsoni and B. microti. Four of the patient's neighbors had reactivity to WA1.

Onchocerciasis is a disease caused by parasitic filarial worms, which are transmitted through bites of black flies. The disease is characterized by nodules in the skin, an itchy rash, and eye lesions. It is one of the world's leading causes of blindness. Researchers have suggested that the immune response to the worm is the major cause of the symptoms of this disease. However, individuals can also mount responses that make them immune to the disease. Onchocerciasis is common in Central and South America and in Africa. From a group of 1,146 long-term residents from five plantations in endemic areas of Guatemala, 778 individuals were confirmed as having onchocerciasis. (An endemic area is one in which a particular disease is always found, but does not cause high mortality.) In infected individuals, the nodules that contained adult worms were shown to contain antibody molecules, indicating that the individuals had mounted an immune response against the worm. The types of antibody were analyzed and found to be of two classes (isotypes) in the majority of individuals. The antibodies primarily reacted with proteins of the worm that were of low molecular weight. Of the individuals studied, 268 never developed disease; 44 of these individuals were from areas that were moderately to highly endemic. Because they are from endemic areas, these individuals are considered to be immune. It is hoped that further study of the immune individuals will allow the identification of the reasons why they did not develop disease, and may lead to methods of preventing onchocerciasis in others. (Consumer Summary produced by Reliance Medical Information, Inc.)

Onchocerciasis is a parasitic disease caused by filarial worms, which are transmitted through bites of black flies. The disease is characterized by nodules in the skin, an itchy rash, and eye lesions. Onchocerciasis is one of the world's leading causes of blindness. It is thought that the immune response to the worm is the major cause of the symptoms associated with the disease. However, individuals can also mount immune responses that prevent them from developing the disease. Onchocerciasis is common in Central and South America and Africa. Long-term residents (778) from endemic areas of Guatemala, who were confirmed as having onchocerciasis, were classified into clinical groups, based on whether they had a history of onchocerciasis and if they had skin nodules containing adult worms or immature worms in their skin. Individuals (44) who lived in the endemic area but never developed the disease were considered to be immune to onchocerciasis and were included in the study. The majority of infected individuals had higher levels of antibodies (molecules made against foreign agents) of two specific classes (isotypes) than uninfected individuals. The levels were highest in those who had adults worms in skin lesions and immature forms in their skin. Antibody of the specific isotype IgG3 was formed against a particular antigen, (a molecule that is recognized as foreign) designed GP20, in the majority of individuals who had immature forms of the worm in their skin. It is this immature form of the worm that is infectious. It is hoped that the identification of a molecule that is recognized as foreign in infected individuals can be developed as a therapeutic agent to prevent disease. (Consumer Summary produced by Reliance Medical Information, Inc.)

Filariasis is a disease that is caused by filarial nematode worms. Wuchereria bancrofti (W. bancrofti) is a filarial nematode that is found in tropical climates; it can be transmitted to humans by the bite of an infected mosquito. Once inside the body, the worms can travel in the blood to various body tissues and to the lymph vessels. While the worms are alive they do not pose a serious threat and may not produce any symptoms. However, when the adult worms die they clog or plug blood and lymph vessels. This can cause inflammation and tissue damage (scaring). In severe cases, elephantiasis (elephant leg) may occur as blood and lymph vessels become clogged with dead worms. Ivermectin and diethylcarbamazine (DEC) have been used to treat patients with filariasis. Both drugs cause fever and muscle pain. While some studies have reported that a single dose of ivermectin may be as effective as 12 days of treatment with DEC, other studies have suggested that DEC may be more effective than ivermectin in treating filariasis. This study was conducted to evaluate the effectiveness of both drugs in treating filariasis. Thirty adult Haitians with filariasis were given a single dose of ivermectin, followed by either one dose of ivermectin, two doses of ivermectin, or 12 days of treatment with DEC. The effectiveness of the drugs was determined by measuring the amount of parasite antigen present in the blood before and after each treatment. DEC reduced the amount of parasite antigen by 75 percent, while ivermectin produced a 34 percent reduction. These results demonstrate that a single dose of ivermectin, followed by a 12-day course of DEC, is the most effective treatment for filariasis. (Consumer Summary produced by Reliance Medical Information, Inc.)

Factors associated with the development of severe malaria have not been well described for cases occurring in the United States (US).

ABSTRACTWe conducted an exploratory investigation in a community in Haiti to determine the prevalence of Cyclospora cayetanensisinfection and to identify potential risk factors for C. cayetanensisinfection. In 2001, two cross-sectional stool surveys and a nested case-control study were conducted. In 2002, a follow-up cross-sectional stool survey was conducted among children =10 years of age. Stool specimens from study participants and water samples from their wells were examined for Cyclosporaand other intestinal parasites. In stools, the prevalence of infection with Cyclosporain persons of all ages decreased from 12% (20 of 167 persons) in February 2001 to 1.1% (4 of 352 persons) in April 2001, a 90.8% decrease. For children =10 years of age, the prevalence rates were 22.5% (16 of 71 children) in February 2001, 3.0% (4 of 135 children) in April 2001, and 2.5% (2 of 81 children) in January 2002. Use of the water from the artesian well in the northern region of the community versus the one in the south was the only risk factor associated with Cyclosporainfection in multivariate analyses (odds ratio, 18.5; 95% confidence interval, 2.4 to 143.1). The water sample from one of the nine wells or water sources tested (one sample per source) in January 2001, shortly before the investigation began, was positive for Cyclosporaby UV fluorescence microscopy and PCR. None of the water samples from the 46 wells or water sources tested during the investigation (one sample per source per testing period, including the artesian wells) were positive for Cyclospora. Further studies are needed to assess the role of water as a possible risk factor for Cyclosporainfection in Haiti and other developing countries.

Infection with Cyclospora cayetanensiscontinues to pose many questions, both in endemic populations and in travelers and food-borne outbreaks. The present review discusses existing knowledge but focuses more on what is yet to be learned about this infection.

Mountain gorillas (Gorilla gorilla beringei)are critically endangered, remaining only in two isolated populations in Central Africa. The objective of this study was to determine the prevalence and intensity of intestinal parasites in a single group of mountain gorillas in Bwindi Impenetrable National Park, Uganda over 7 weeks from June to August 2000. Fecal samples were collected from night nests and transported in formalin for examination at Cornell University and the Centers for Disease Control. All fecal samples were examined microscopically for parasitic larvae, cysts, and eggs. The following were found: strongylid eggs, Probstymariasp. larvae, and two parasitic nematode larvae that were not identified. Additional examination techniques will be used to further examine the fecal material specifically for protozoan cysts. An increasing threat to this group of gorillas is the presence of local field assistants and researchers. We found no evidence of human parasites in the fecal samples from this gorilla group.

ABSTRACTWe undertook a study to evaluate Streck tissue fixative (STF) as a substitute for formalin and polyvinyl alcohol (PVA) in fecal preservation. A comparison of formalin, PVA, (mercuric chloride based), and STF was done by aliquoting fecal samples into each fixative. Stool specimens were collected in Haiti, and parasites includedCyclospora cayetanensis, Giardia intestinalis,Entamoeba coli, Iodamoeba butschlii,Endolimax nana, Ascaris lumbricoides,Trichuris trichiura, Strongyloides stercoralis, and Necator americanus. Preserved stools were examined at various predetermined times (1 week, 1 month, and 3 months) to establish the quality of the initial preservation as well as the suitability of the fixative for long-term storage. At each time point, stool samples in fixatives were examined microscopically as follows: (i) in wet mounts (with bright-field and epifluorescence microscopy), (ii) in modified acid-fast-, trichrome-, and safranin-stained smears, and (iii) with two commercial test kits. At the time points examined, morphologic features remained comparable for samples fixed with 10% formalin and STF. For comparisons of STF- and 10% formalin-fixed samples, specific findings showed that Cyclosporaoocysts retained full fluorescence, modified acid-fast- and safranin-stained smears of Cryptosporidiumand Cyclosporaoocysts were equal in staining quality, and results were comparable in the immunofluorescence assay and enzyme immunoassay commercial kits. Stool fixed in STF and stained with trichrome showed less-than-acceptable staining quality compared with stool fixed in PVA. STF provides an excellent substitute for formalin as a fixative in routine examination of stool samples for parasites. However, modifications to the trichrome staining procedures will be necessary to improve the staining quality for protozoal cysts fixed in STF to a level comparable to that with PVA.

In this article, the authors describe how to detect blood-borne and skin-dwelling filarial infections parasitologically. Considerable space is devoted to identifying and separating microfilarial from nonparasite objects, and the evaluation of morphologic features, including size, shape, and internal anatomy is stressed.

A differential diagnosis of inflammatory periocular soft tissue masses includes sarcoidosis, ruptured dermoid cyst, infectious abscess, metastatic neoplastic disease, and idiopathic pseudotumor. The authors present the case of a 42-year-old woman with a periocular inflammatory mass caused by dirofilaria of a nematode classification as Dirofilaria tenuis.The extraction of the worm was curative and the patient has been symptom-free for the ensuing 12 months. This zoonotic infection, spread by mosquito vectors from animal hosts to humans, is rarely encountered in the United States as a cause of periorbital inflammation. A history of migratory swelling and residence in, or travel to, endemic areas (the southeastern United States) should suggest the possibility of Dirofilariainfection.

SUMMARYFilariae of animals, especially those of mammals, often infect humans and typically produce cryptic infections. These “zoonotic” infections have been reported from virtually all parts of the world including temperate zones. Infections may be symptomatic or not, and the parasites are found in surgical tissue biopsy specimens or, more rarely, are removed intact from superficial sites such as the orbit or conjuctivae. Typically, these worms tend to occupy tissue sites similar to those occupied in the natural animal host, with the exception of the eyes. Many kinds of filariae have been isolated from humans, including species of Dirofilaria, Brugia, Onchocerca, Dipetalonema, Loaina and Meningonema. Worms have been found in subcutaneous tissues, the heart and lungs, lymphatics, the eye, and the central nervous system. Specific identification of these filariae is based on their morphological features in histologic sections. Unfortunately, some of these worms cannot be identified even at the generic level. There are other species of filariae, presumed to be zoonotic, which produce patent infections in humans but are poorly and incompletely known. These include Microfilaria semiclarum and Microfilaria bolivarensis. It is probable that almost any filaria parasitizing animals can, under proper circumstances, infect humans and undergo some degree of development. Undoubtedly, additional species of filariae will continue to be isolated from humans in the future.

ABSTRACTZoonotic anatrichosomiasis in a mother and daughter is reported. Both presented with a 10-week history of multiple painful oral ulcers. Biopsy specimens revealed the presence of small, coiled trichuroid nematodes with distinctive morphological features, including stichocytes and paired bacillary bands. This represents an unusual infection by a zoonotic Anatrichosomaspecies.

To characterize filarial antigens that may beassociated with the development of chronic lymphatic dysfunction in persons with lymphatic filariasis, T cell responsiveness to Brugia pahangi adult worm extracts and SDS-PAGE antigen fractions were examined among Haitians from an area in which Wuchereria bancrofti is endemic. Greater T cell proliferation and interleukin-10 (IL-10) production were observed in amicrofilaremic patients with hydrocele or elephantiasis than in amicrofilaremic or microfilaremic asymptomatic persons. Antigen fractions that stimulated the highest proliferative responses (in the 25-49 kDa range) and IL-10 production were not identical. Further separation of an immunodominant 30- to 38-kDa fraction by ion exchange high-pressure liquid chromatography identified several subfractions, including a 32-kDa protein band, that elicited T cell responses from patients with elephantiasis or hydrocele. By immunoblot, these patients also had markedly greater humoral reactivity to parasite antigens of ∼52,43, 32, and 30 kDa.

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.

This study assessed Wuchereria bancrojti-infected patients who received diethylcarbamazine (DEC) to determined if drug levels were comparable between individuals who continued to harbor circulating microfilariae and those whose blood became clear of parasites, between those with high and low microfilaria counts, and between infected and noninfected persons. Haitian volunteers undergoing treatment for W. bancrofti and two nonendemic controls were enrolled. DEC levels in serum and urine samples were determined using a gas chromatographic method. No correlation was found between pre- and posttreatment microfilarial levelsand drug levels. Drug levels were comparable in persons with or without residual microfilaria and in infected and uninfected persons. These results indicate that incomplete drug regimens, differences in serum drug levels, and inadequate drug dosage are not the primary causes of treatment failure and suggest there is a degree of parasite tolerance for DEC.

The relationship between chronic obstructive disease and antifilarial immune responsiveness was studied in the Haitian community of Leogane, where Wuchereria bancrofti is endemic. Differences in sex ratios and in the prevalence of microfilaremia were observed between patients with hydrocele and those with lymphedema or elephantiasis of the lower limb. Only 2 of 84 patients with limb involvement (74 women, 10 men) were microfilaremic compared with 25 of 42 men with hydrocele. Microfilaria-positive men with hydrocele had significantly lower IgG2 and proliferative responses to filarial antigen than did amicrofilaremic men with hydrocele or individuals with lymphedema or elephantiasis. Parasite-specific cellular responses of amicrofilaremic individuals with obstructive disease were greater, although not significantly so, than those of amicrofilaremic asymptomatic members of the community. These results are compatible with the hypothesis that development of obstructive disease of the lymphatics has an immune component in amicrofilaremic persons.

Hydrocele and elephantiasis, major clinical manifestations of bancroftian filariasis, are thought to share a common pathogenesis. The characteristics of 121 patients with hydrocele or elephantiasis in Leogane, Haiti, were compared: 39% of 57 men with hydrocele and 3% of 64 persons with lymphedema of the leg were microfilaria-positive (P < .001). Circulating filarial antigen, presumably from the adult worm, was detected in 15 (43%) microfilaria-negative men with hydrocele and 9 (15%) microfilaria-negative persons with leg edema (P = .004). Microfilaria-positive men had lower levels of filaria-specific IgG1 and hydroceles of significantly smaller volume and shorter duration than did microfilaria-negative men; hydrocele volume was inversely associated with microfilarial density (P = .001). In contrast, filarial antigen but not microfilariae was associated with filaria-specific IgG4 and decreased lymphocyte proliferation. Antigen status was not associated with severity of leg edema. In this filariasis-endemic area, men with hydrocele are more immunologically and parasitologically heterogeneous than are persons with elephantiasis.

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.

Patent filarial infections are associated with elevated levels of parasite-specific IgG4. This study investigated the shifts of filarial-specific human IgG and IgG4 antibodies after diethylcarbamazine and ivermectin treatment of bancroftian filariasis. Thirty adult Haitians were treated first with a l-mg clearing dose of ivermectin and then with either one or two 200µg/kg doses of ivermectin or with 12 daily 6-mg/kg doses of diethylcarbamazine. Posttreatment levels of antifilarial IgG4 were dependent on both treatment group and time of follow-up, IgG4 increased markedly to a maximum by day 30 in all treatment groups and then began to decrease; the greatest decrease was among diethylcarbamazine-treated patients. Posttreatment microfilaremia was inversely correlated with the decrease in IgG4; thus, shifts in IgG4 were associated with treatment response for all groups. Antifilarial IgG levelswere not correlated with drug treatment and did not change to the same degree as did IgG4 responses.

Previous reports have demonstrated age-related shifts in antifilarial humoral immune responses in 6- to 10-year-old Haitian children; the responses consisted of elevated parasite-specific IgG 2 and IgG3 in amicrofilaremic children and elevated IgG4 in microfilaremic children. In this study, the cell-mediated immune responses to soluble adult and microfilarial extracts of Brugia pahangi, determined by use of a microblastogenesis assay, were examined. Capillary blood samples were collected by finger prick from 176 Haitian children in an area with endemic Wuchereria bancrofti. Antigen-specific cellular responsiveness varied as a function of infection status but not age or sex; amicrofilaremic children had significantly greater responses to adult antigens than did microfilaremic children. Significant responses were detected in children <2 years of age; thus, correlations observed between filarial antigen-specific responses and infection status are established early in life.

Antifilarial IgG4 is a marker of active filarial infection; however, 10% of microfilaremic persons may have low levels of antifilarial IgG4. To gain insight into how persons with microfilaremia with low antifilarial IgG4 levels (<10 µ/mL) differ from those with high levels (>170 µg/mL), total IgG4 and IgE and filaria-specific IgE, IgG1, and IgG2 were measured by ELISA in serum samples collected from 85 microfilaremic Haitians. Persons with lower levels of antifilarial IgG4 had significantly lower total IgG4 and total IgE (P < .01), lower levels of antifilarial IgG1, IgG2, and IgE (P < .01, = .03, and < .01, respectively), and higher antigenemia and microfilaremia (P < .01) than did persons with higher levels of antifilarial IgG4. Increased antigen loads in microfilaremic persons may be associated with a down-regulation of antibody production, which extends to all isotypes.

Albendazole chemotherapy of larval Echinococcus multilocularis was studied in the Mongolian jird by administration of medicated feed at various concentrations and durations. The effects were evaluated by comparison of treated and control groups in terms of host mortality, larval metastases to the lungs, and final weight and histologic appearance of larval tissue. Viability of larval tissue at necropsy of each animal was tested by inoculation into two noninfected jirds. Albendazole-medicated feed (0.05%–0.10%) significantly inhibited larval growth. Other effects of the drug included larval degeneration and necrosis, inhibition of protoscolex formation, decreased pulmonary metastases, and reduced mortality of hosts. Adverse effects on the parasite correlated significantly with serum albendazole metabolite levels and duration of therapy. However, serum albendazole levels in jirds equal to or exceeding concentrations achieved in humans receiving daily doses of 10 mg/kg of body weight did not kill the 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 WAl-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.