Malaria rapid diagnostic devices: performance characteristics of the ParaSight F device determined in a multisite field study.

Microscopic detection of parasites has been the reference standard for malaria diagnosis for decades. However, difficulty in maintaining required technical skills and infrastructure has spurred the development of several nonmicroscopic malaria rapid diagnostic devices based on the detection of malaria parasite antigen in whole blood. The ParaSight F test is one such device. It detects the presence of Plasmodium falciparum-specific histidine-rich protein 2 by using an antigen-capture immunochromatographic strip format. The present study was conducted at outpatient malaria clinics in Iquitos, Peru, and Maesod, Thailand. Duplicate, blinded, expert microscopy was employed as the reference standard for evaluating device performance. Of 2,988 eligible patients, microscopy showed that 547 (18%) had P. falciparum, 658 (22%) had P. vivax, 2 (0.07%) had P. malariae, and 1,750 (59%) were negative for Plasmodium. Mixed infections (P. falciparum and P. vivax) were identified in 31 patients (1%). The overall sensitivity of ParaSight F for P. falciparum was 95%. When stratified by magnitude of parasitemia (no. of asexual parasites per microliter of whole blood), sensitivities were 83% (>0 to 500 parasites/microl), 87% (501 to 1,000/microl), 98% (1,001 to 5,000/microl), and 98% (>5,000/microl). Device specificity was 86%.

Comparison of IsoCode STIX and FTA Gene Guard collection matrices as whole-blood storage and processing devices for diagnosis of malaria by PCR.

We compared two collection devices, IsoCode and FTA, with whole blood for the diagnosis of malaria by PCR (n = 100). Using whole blood as the reference standard, both devices were sensitive for the detection of single-species malaria infections by PCR (> or =96%). However, the detection of mixed infections was suboptimal (IsoCode was 42% sensitive, and FTA was 63% sensitive).

Protection of Aotus monkeys by Plasmodium falciparum EBA-175 region II DNA prime-protein boost immunization regimen.

Aotus monkeys received 4 doses of Plasmodium falciparum EBA-175 region II vaccine as plasmid DNA (Dv-Dv) or recombinant protein in adjuvant (Pv-Pv) or as 3 doses of DNA and 1 dose of protein (Dv-Pv). After 3 doses, antibody titers were approximately 10(4) in DNA-immunized monkeys and 10(6) in protein-immunized monkeys. A fourth dose did not significantly boost antibody responses in the Dv-Dv only or Pv-Pv only groups, but titers were boosted to approximately 10(6) in monkeys in the Dv-Pv group. Four weeks after the last immunization, the animals were challenged with 10(4) P. falciparum-parasitized erythrocytes. Peak levels of parasitemia were lower in the 16 monkeys that received region II-containing plasmids or proteins than in the 16 controls (geometric mean: 194,178 and 410,110 parasites/microL, respectively; P=.013, Student's t test). Three of 4 monkeys in the Dv-Pv group did not require treatment. These data demonstrate that immunization with EBA-175 region II induces a significant antiparasite effect in vivo.

The epidemiology of malaria in an epidemic area of the Peruvian Amazon.

A longitudinal study of malariometric indicators and their association with potential risk factors was conducted during August 1997-July 1998 at Padre Cocha, a village of 1,400 residents in the Peruvian Amazon. The incidence of Plasmodium falciparum infections during the study year was 166/1,000 persons; that of P. vivax was 826/1,000 persons. The mean duration of symptoms prior to diagnosis was 2 days; presenting geometric mean parasite densities were 3,976 parasites/microl for P. falciparum infections and 2,282 parasites/microl for P. vivax. There were no malaria-associated deaths. Consistent with the epidemic nature of malaria in the area, the incidence of both parasite species increased with age and there were no age-specific differences in mean parasite densities. No specific occupational risks for malaria were identified. Activities significantly associated with malaria risk reflected local vector behavior and included strolling outdoors after 6:00 PM and arising before 6:00 AM for adults, and attending evening church services for children.

Safety and efficacy of intravenous sodium stibogluconate in the treatment of leishmaniasis: recent U.S. military experience.

The efficacy and toxicity of sodium stibogluconate (SSG) at a dosage of 20 mg/(kg.d) for either 20 days (for cutaneous disease) or 28 days (for visceral, mucosal, or viscerotropic disease) in the treatment of leishmaniasis is reported. Ninety-six U.S. Department of Defense health care beneficiaries with parasitologically confirmed leishmaniasis were prospectively followed for 1 year. One patient was infected with human immunodeficiency virus; otherwise, comorbidity was absent. Clinical cure occurred in 91% of 83 cases of cutaneous disease and 93% of 13 cases of visceral/viscerotropic disease. Adverse effects were common and necessitated interruption of treatment in 28% of cases, but they were generally reversible. These included arthralgias and myalgias (58%), pancreatitis (97%), transaminitis (67%), headache (22%), hematologic suppression (44%), and rash (9%). No subsequent mucosal leishmaniasis was identified, and there were no deaths attributable to SSG or leishmaniasis.

Fever in the returned traveler.

The most important cause of fever in the returned traveler is malaria. All febrile patients in which malaria is epidemiologically possible require urgent evaluation for P. falciparum malaria, which can be rapidly fatal in the nonimmune patient. Early diagnosis and therapy can prevent severe morbidity and mortality. Other less common causes of undifferentiated fever include acute schistosomiasis, the enteric fevers, rickettsial diseases, leptospirosis, and dengue fever. Early empiric therapy for suspected leptospirosis and the rickettsial infections is encouraged to decrease morbidity and mortality. About a quarter of febrile patients do not have an etiologic agent determined for their illness but recover without sequelae. Patients with fever and hemorrhagic manifestations within 3 weeks of their return need to be isolated for the remote possibility of a highly transmissible agent. Although the febrile traveler is always a challenge, the real world differential diagnosis is limited and a systematic approach via the history, physical examination, and selected laboratory tests is usually sufficient to confirm the diagnosis or eliminate potentially serious infections.

Short report: detection of Leishmaniavirus in human biopsy samples of leishmaniasis from Peru.

Leishmaniavirus is a double-stranded RNA virus that persistently infects some strains of the protozoan parasite Leishmania. There is considerable interest in the possibility that the presence of this virus alters parasite phenotype and may affect disease pathogenesis. If so, the virus marker could provide a valuable prognostic indicator for human leishmaniasis, particularly in those cases caused by New World parasite strains. The virus has been detected in cultured L. braziliensis, L. b. guyanensis, and L. major. To date there has been no information as to the extent of infection in samples prior to culturing in the laboratory. This study demonstrates, through the reverse transcription-polymerase chain reaction, that Leishmaniavirus exists in human biopsy samples of leishmaniasis prior to manipulation in culture.

Plasmodium vivax infections in U.S. Army troops: failure of primaquine to prevent relapse in studies from Somalia.

Different strains of Plasmodium vivax vary in their sensitivity to primaquine, the only drug that prevents relapses. Described are the clinical data and relapse pattern for 75 soldiers treated for vivax malaria since returning from Somalia. Following their initial attack of malaria, 60 of the 75 cases received a standard course of primaquine (15 mg base daily for 14 days). Twenty-six of the 60 soldiers subsequently relapsed for a failure rate of 43%. Eight soldiers had a second relapse following primaquine therapy after both the primary attack and first relapse. Three of these soldiers had received a higher dosage of primaquine (30 mg base daily for 14 days) after their second attack. The apparent ineffectiveness of primaquine therapy in preventing relapses suggests the presence of primaquine-resistant P. vivax strains in Somalia.

Malaria among United States troops in Somalia.

PURPOSE: United States military personnel deployed to Somalia were at risk for malaria, including chloroquine-resistant Plasmodium falciparum malaria. This report details laboratory, clinical, preventive, and therapeutic aspects of malaria in this cohort. PATIENTS AND METHODS: The study took place in US military field hospitals in Somalia, with US troops deployed to Somalia between December 1992 and May 1993. Centralized clinical care and country-wide disease surveillance facilitated standardized laboratory diagnosis, clinical records, epidemiologic studies, and assessment of chemoprophylactic efficacy. RESULTS: Forty-eight cases of malaria occurred among US troops while in Somalia; 41 of these cases were P falciparum. Risk factors associated with malaria included: noncompliance with recommended chemoprophylaxis (odds ratio [OR] 2.4); failure to use bed nets (OR 2.6); and failure to keep sleeves rolled down (OR 2.2). Some patients developed malaria in spite of mefloquine (n = 8) or doxycycline (n = 5) levels of compatible with chemoprophylactic compliance. Five mefloquine failures had both serum levels > or = 650 ng/mL and metabolite:mefloquine ratios over 2, indicating chemoprophylactic failure. All cases were successfully treated, including 1 patient who developed cerebral malaria. CONCLUSIONS: P falciparum malaria attack rates were substantial in the first several weeks of Operation Restore Hope. While most cases occurred because of noncompliance with personal protective measures or chemoprophylaxis, both mefloquine and doxycycline chemoprophylactic failures occurred. Military or civilian travelers to East Africa must be scrupulous in their attention to both chemoprophylaxis and personal protection measures.

Characterization of a Leishmania tropica antigen that detects immune responses in Desert Storm viscerotropic leishmaniasis patients.

A chronic debilitating parasitic infection, viscerotropic leishmaniasis (VTL), has been described in Operation Desert Storm veterans. Diagnosis of this disease, caused by Leishmania tropica, has been difficult due to low or absent specific immune responses in traditional assays. We report the cloning and characterization of two genomic fragments encoding portions of a single 210-kDa L. tropica protein useful for the diagnosis of VTL in U.S. military personnel. The recombinant proteins encoded by these fragments, recombinant (r) Lt-1 and rLt-2, contain a 33-amino acid repeat that reacts with sera from Desert Storm VTL patients and with sera from L. tropica-infected patients with cutaneous leishmaniasis. Antibody reactivities to rLt-1 indicated a bias toward IgG2 in VTL patient sera. Peripheral blood mononuclear cells from VTL patients produced interferon gamma, but not interleukin 4 or 10, in response to rLt-1. No cytokine production was observed in response to parasite lysate. The results indicate that specific leishmanial antigens may be used to detect immune responses in VTL patients with chronic infections.

Epidemiology of the leishmaniases.

The leishmaniases are a group of zoonotic infections caused by protozoan parasites of the genus Leishmania. These infections produce a variety of different clinical diseases depending on the virulence or tropism of the parasite and differential host immune responses. Newly recognized clinical presentations, such as viscerotropic leishmaniasis in American military veterans of Operation Desert Storm, continue to challenge clinicians. Epidemics of classic visceral leishmaniasis leading to thousands of deaths are ongoing in Brazil, India, and the Sudan. Epidemics of localized cutaneous leishmaniasis are ongoing in many areas of South America, North Africa, and Central Asia. A marked increase in cases is often associated with an influx of nonimmune populations into newly cleared agricultural populations into newly cleared agricultural areas or population expansion into previously unsettled areas surrounding cities. The emergence of leishmaniasis as an important opportunistic infection in AIDS patients portends an ominous future as the HIV pandemic sweeps into the hyperendemic areas of South America, Africa, and the Indian subcontinent. Parenteral transmission via needle sharing in HIV coinfected individuals in Spain is an epidemiologically significant new mode of transmission. Finally, recent work has elucidated an enzootic transmission cycle involving L. mexicana in Texas.

Hypereosinophilic syndrome associated with HIV infection. Military Medical Consortium for Applied Retroviral Research.

A hypereosinophilic syndrome associated with dermatitis has been observed rarely in association with HIV infection. We describe the case of a young man with AIDS who came to us with a diffuse cutaneous eruption, fever, angioedema, eosinophilia, and a mildly elevated serum IgE level. No allergic or infectious cause of this illness could be determined, and the patient was treated with corticosteroids and PUVA therapy, resulting in complete resolution of the dermatitis and associated findings. In this case, there were clinical and histopathologic similarities to the idiopathic hypereosinophilic syndrome and to acute graft-versus-host disease. The serum level of the cytokine interleukin-5 (IL-5), which is associated with eosinophil production, was found to be mildly elevated during the peak of the eruption, while samples drawn previously and subsequently were not. Although it appears that the syndrome we describe is associated with the measurably elevated level of IL-5, further investigation is required to determine whether there is a cause and effect relationship between IL-5 and this entity. A brief review of the literature concerning eosinophils and HIV infection is also presented in the context of this case.

Pancreatitis induced by pentavalent antimonial agents during treatment of leishmaniasis.

Pentavalent antimony (Sbv), formulated as sodium stibogluconate or meglumine antimoniate, is the standard treatment for the leishmaniases. In 16 of 17 consecutive, prospectively observed patients in Washington D.C., serum levels of amylase and lipase rose to abnormal values after therapy with sodium stibogluconate was started; 12 of 17 had symptoms of pancreatitis. Sbv therapy was continued to completion in 7 of 17 patients and interrupted in 10 of 17. Pancreatitis improved in every patient after Sbv therapy was stopped. Sbv treatment was resumed after brief interruptions in 6 of 10 patients. All six of these patients had flares of pancreatitis, but each completed therapy. Subsequently, we measured amylase and lipase levels in stored sera from 32 patients treated in Peru with either sodium stibogluconate or meglumine antimoniate for mucosal leishmaniasis. In all 32 Peruvian patients, serum amylase and lipase rose to abnormal levels during Sbv therapy; 11 of 32 had symptoms of pancreatitis. Standard Sbv regimens induce pancreatitis in almost all patients, but continued therapy is often tolerated; pancreatitis subsides when therapy is stopped, and rechallenge may be tolerated after a brief halt in treatment.

Survivability and infectivity of viscerotropic Leishmania tropica from Operation Desert Storm participants in human blood products maintained under blood bank conditions.

To assess the potential for leishmaniasis being transmitted through blood transfusion, we studied the survival of Leishmania in blood products under blood bank storage conditions. We report that L. tropica- or L. donovani-contaminated transfusable blood products are a risk to the blood supply for at least 25 days postdonation under blood bank general conditions. The blood components that have been implicated are whole blood, packed red blood cells, platelet concentrate, and frozen-deglycerolized red blood cells, but not, as would be expected, fresh frozen plasma. Blood units containing four infected monocytes per milliliter of blood with a mean of three amastigotes per monocyte contain viable parasites for 15 days under blood bank storage conditions. Furthermore, animal studies showed the presence of parasites in the blood of cutaneously infected animals and the possibility of transmitting the disease to healthy experimental animals by blood transfusion from infected animal donors. Three of three BALB/C mice showed metastasis to the lower extremities and face after they received 0.25 ml of blood from a CPDA-1 bag seeded with 1.5 x 10(5) amastigotes per ml of blood kept under blood bank conditions for 30 days. This proves that Leishmania not only survives blood banking procedures and storage conditions but that the parasite retains its infectivity. The results of this study and the recent demonstration of L. tropica-infected monocytes in the blood of a patient returning from Southwest Asia suggests that transfusion-associated leishmaniasis can occur.

Identification and genetic comparison of leishmanial parasites causing viscerotropic and cutaneous disease in soldiers returning from Operation Desert Storm.

Six Leishmania major and seven L. tropica parasites were isolated and identified from participants in Operation Desert Shield/Storm. A complete enzyme analysis (21 enzymes) revealed that there was enzyme polymorphism among the isolates of each species group. Any one Desert Storm L. major isolate could differ from any other for 1-3 enzymes, and any L. tropica isolate could differ from any one other for up to eight enzymes. Enzyme polymorphism data from other L. major and L. tropica isolates from Africa and the Middle East region were obtained and combined with the Desert Storm data to produce population enzyme polymorphism estimates. Results from these population data indicated that L. major parasites could be expected to differ from each other for as many as eight enzymes and still be L. major, and similarly, L. tropica isolates could differ for as many as 14 enzymes. These expected isolate variation extremes have not been observed among the isolates studied. All L. major and most L. tropica isolates were from patients who, as expected, presented with cutaneous disease, but the Desert Storm and two Kenyan patients infected with L. tropica presented with a viscerotropic disease, the symptoms of which are unlike those of classic visceral leishmaniasis. Such unrecognized presentation for these L. tropica-infected patients indicates that both parasite and patient can play critical roles in disease manifestations. The Desert Storm isolates are, as indicated, either L. major or L. tropica.

Visceral infection caused by Leishmania tropica in veterans of Operation Desert Storm.

BACKGROUND: Visceral leishmaniasis, usually caused by Leishmania donovani, has rarely been reported from eastern Saudi Arabia, so it was not expected to affect the soldiers of Operation Desert Storm. METHODS: We evaluated eight soldiers with visceral leishmanial infection, examining their serum with an immunofluorescent-antibody assay, examining their marrow or biopsy tissue for amastigotes with an indirect immunofluorescent-monoclonal-antibody assay, and culturing the parasites. Cultured promastigotes were isolated and characterized by isoenzyme analysis. RESULTS: None of the eight soldiers had classic signs or symptoms of visceral leishmaniasis (kala-azar). Seven soldiers had unexplained fever, chronic fatigue, malaise, cough, intermittent diarrhea, or abdominal pain that began up to seven months after they returned to the United States; one had no symptoms. Five had adenopathy or mild, transient hepatosplenomegaly. None had cutaneous manifestations. Diagnoses were made by bone marrow aspiration (seven patients) or lymph-node biopsy (one patient). Six isolates have been identified as L. tropica, which usually causes only cutaneous disease. Of the six patients treated with sodium stibogluconate, five improved and one remained symptomatic. CONCLUSIONS: L. tropica can produce visceral infection that can cause unexplained systemic illness in persons returning from areas where this organism is endemic.