Novel Temperature-Dependent Development Rate Models for Postdiapause Egg Eclosion of Three Important Arthropod Pests Found in Commercial Christmas Tree Plantations of Southern Québec, Canada.

The balsam twig aphid Mindarus abietinus Koch (Hemiptera: Aphididae), the spruce spider mite Oligonychus ununguis (Jacobi) (Acari: Tetranychidae), and the pine needle scale Chionaspis pinifoliae (Fitch) (Hemiptera: Diaspididae) are three important pests for the Christmas tree industry of Québec, Canada. Temperature-dependent development rates for postdiapause overwintering eggs of these species have never been studied for populations of southern Québec, where the vast majority of Christmas trees are grown. The accumulation of physiological time in growing degree days (GDD) is a standard tool to predict egg eclosion dates for pests, when first generation immatures are most vulnerable to insecticidal control. Development rates for postdiapause eggs were tested at four or five constant temperatures in the 11-23°C range under controlled conditions, based on time before hatching for eggs collected in a balsam fir plantation in late winter. The standard linear model and three published nonlinear models were fitted to the data and compared for their ability to estimate key biological temperature parameters and to predict development rates of postdiapause eggs. Validation of model predictions of egg eclosion time on balsam fir in the field was reasonably accurate using the classical linear model where field-accumulated GDD were calculated with a particular interpretation of the average method based on daily maximum and minimum temperatures. The linear model could predict mean egg eclosion within around 5 d of eclosion dates observed in the field.

Managing malaria in the intensive care unit.

The number of people travelling to malaria-endemic countries continues to increase, and malaria remains the commonest cause of serious imported infection in non-endemic areas. Severe malaria, mostly caused by Plasmodium falciparum, often requires intensive care unit (ICU) admission and can be complicated by cerebral malaria, respiratory distress, acute kidney injury, bleeding complications, and co-infection. The mortality from imported malaria remains significant. This article reviews the manifestations, complications and principles of management of severe malaria as relevant to critical care clinicians, incorporating recent studies of anti-malarial and adjunctive treatment. Effective management of severe malaria includes prompt diagnosis and early institution of effective anti-malarial therapy, recognition of complications, and appropriate supportive management in an ICU. All cases should be discussed with a specialist unit and transfer of the patient considered.

Falciparum malaria in malaria-naive travellers and African visitors.

BACKGROUND: Patients from malaria-endemic areas who present in non-endemic countries with Plasmodium falciparum malaria are often assumed to have some degree of immunity. If this were reliably true, it would simplify their management. AIM: To determine whether being born and resident in a malaria-endemic country is a predictor of clinical course in UK admissions for malaria. DESIGN: Prospective observational study. METHODS: We compared clinical and laboratory parameters between two groups of adult patients with acute P. falciparum malaria, admitted to the Hospital for Tropical Diseases in London: one born and resident in non-endemic countries (n=167); the other born and resident in malaria-endemic countries of Africa (n=93). Patients were excluded if they had taken prophylaxis or prior treatment. RESULTS: There were no differences between these two groups in terms of peak parasitaemia or time to parasite clearance. There was a significantly higher risk of malaria-naive patients having peak parasitaemia >5% (OR 4.5, 95%CI 1.5-13.2). Of those usually resident in Africa, 31% required parenteral treatment compared to 41% of the malaria-naive group. Of the visitors from Africa, 4.3% needed admission to the Intensive Therapy Unit (ITU), although there was a tendency for more malaria-naive patients to require ITU care (OR 2.69, 95%CI 0.9-8.1). DISCUSSION: While there are differences in presentation between those who are malaria-naive and those who live in malaria-endemic African countries, making assumptions about the immunity or clinical course of an individual patient with malaria presenting in the UK on the basis of presumed history of exposure is unwise.

Schistosomiasis prophylaxis in vivo using N,N-diethyl-m-toluamide (DEET).

Topical N,N-Diethyl-m-toluamide (DEET) was studied as a schistosomiasis prophylactic in vivo for the use of individuals with limited exposure. Fifteen subjects, on a 3-week expedition to Lake Malawi in September 2001, applied 50% DEET to their skin after exposure to lake water. No subjects developed evidence of a new infection at 3-month follow-up.

A phase I safety and immunogenicity trial with the candidate malaria vaccine RTS,S/SBAS2 in semi-immune adults in The Gambia.

RTS,S is a novel pre-erythrocytic malaria vaccine based on the circumsporozoite surface protein (CSP) of Plasmodium falciparum linked to hepatitis B surface antigen (HBs) and combined with a novel adjuvant system (SBAS2). We have conducted a Phase I trial with three doses of this vaccine given at 0, 1, and 6 months to 20 semi-immune, adult, male volunteers in The Gambia to assess its safety and immunogenicity. Eighteen of the 20 volunteers completed the study. There were no clinically significant local or systemic adverse events following each vaccination. Hematologic and biochemical indices before and two weeks after each vaccination showed no evidence of toxicity. Antibody titers to both CSP and HBs showed a significant increase after vaccination; these were the largest after the third dose. We conclude that the RTS,S/SBAS2 vaccine induces no significant toxicity in this semi-immune population and produces significant increases in antibody titers to CSP.

A randomized safety and tolerability trial of artesunate plus sulfadoxine--pyrimethamine versus sulfadoxine-pyrimethamine alone for the treatment of uncomplicated malaria in Gambian children.

Artemisinin derivatives, such as artesunate, have a short half-life and very rapid anti-malarial activity. Theoretically, using such agents in conjunction with well-established anti-malarial drugs such as sulfadoxine-pyrimethamine may reduce the rate of drug resistance. Such a combination has not previously been used in Africa. We have conducted a pilot safety trial of artesunate (4 mg/kg for 3 days) given with a single dose of sulfadoxine-pyrimethamine (25 mg/kg sulfadoxine) compared to sulfadoxine-pyrimethamine alone among 40 Gambian children with uncomplicated malaria. Both regimens were safe and well tolerated and there were no adverse experiences attributed to the combination. The addition of artesunate resulted in a higher proportion of afebrile children and children with a negative blood film on Day 2, and a reduction in the proportion of gametocyte carriers, when compared to sulfadoxine-pyrimethamine alone.

Short report: hematologic changes in acute, imported Plasmodium falciparum malaria.

We conducted a retrospective analysis of hematologic changes in 89 patients with imported Plasmodium falciparum malaria. Thirteen (15%) were anemic at presentation, 60 (67%) had thrombocytopenia, and 63% had lymphopenia. There was a significant inverse relationship between parasitemia and platelet count. Anemia is rare among patients with imported malaria, while thrombocytopenia and lymphopenia are common.

As the world of managed care turns.

Health maintenance organizations have become predominant in the health care industry and continue to evolve as expectations for quality and affordability change. Although initially limited, managed care options have grown extensively and will continue to develop as America's needs change. The author describes the early impetus for the growth of MCOs and the legislation that guided the maturation of managed care.

Fever as the presenting complaint of travellers returning from the tropics.

We investigated prospectively the cause of fever in patients requiring hospitalization after returning from the tropics. All consecutive admissions (n = 195) with oral temperature > 37.0 degrees C at the time of admission were enrolled. Final diagnosis as recorded on the discharge summary by the attending physician and results of any relevant laboratory or radiological investigations were recorded on standard proforma. Malaria accounted for 42% of admissions; two patients had returned to Britain more than 6 months before presentation. The second largest group was assumed to have a non-specific viral infection (25%). Cosmopolitan infections (urinary tract infection, community-acquired pneumonia, streptococcal sore throat, etc.) accounted for 9%. Coincidental infections (schistosomiasis, filariasis, intestinal helminths) were found in 16%. Serology was positive for HIV infection in 3%. The most useful investigation was a malaria film, which was positive in 45% of cases in which it was performed. The combination of thrombocytopaenia (platelet count < 100 x 10(9)) and hyperbilirubinaemia (bilirubin > 18 IU/ml) were useful predictive markers of malaria: all 23 patients with both abnormalities had positive malaria films. Malaria must be excluded in any febrile patient returning from the tropics. In the absence of a positive malaria film, the combination of a low platelet count and raised bilirubin may suggest the need for an empirical course of therapy.

Peroxisomes and the hepatic pathology of childhood malnutrition.

Liver specimens obtained immediately after death from eight severely malnourished children were examined by electron microscopy, and compared with seven liver biopsy specimens from children who had recovered from malnutrition. The liver cells from the fatal cases showed mitochondrial swelling, with coarse densities in the matrix, cholestasis, depletion of the endoplasmic reticulum and Golgi apparatus, diminished glycogen stores, prominent lipid deposits and focal cytoplasmic degradation. The nucleoli were enlarged. There was marked reduction in peroxisomes. In contrast, the biopsies from recovering children showed good cellular organisation, and a normal frequency of peroxisomes. Multiple factors, including sepsis, may lead to depletion of peroxisomes. Loss of peroxisomes may interrupt beta-oxidation of long-chain fatty acids and accentuate the accumulation of lipid. Moreover, a reduction in the concentration of catalase may remove one avenue for the detoxification of free radicals. As the concentration of other anti-oxidants, notably glutathione, is also reduced, free radical damage may occur, leading to lipid peroxidation of membranes, mitochondrial damage, pump failure and influx of water and electrolytes into the cell.