Statistics for Spatial Data.

Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

Citation classic - optimal foraging - a selective review of theory and tests

Background
Malaria is an important cause of illness and death in many parts of the world, especially in sub-Saharan Africa. There has been a renewed emphasis on preventive measures at community and individual levels. Insecticide-treated nets (ITNs) are the most prominent malaria preventive measure for large-scale deployment in highly endemic areas.

Objectives
To assess the impact of insecticide-treated bed nets or curtains on mortality, malarial illness (life-threatening and mild), malaria parasitaemia, anaemia, and spleen rates.

Search methods
I searched the Cochrane Infectious Diseases Group trials register (January 2003), CENTRAL (The Cochrane Library, Issue 1, 2003), MEDLINE (1966 to October 2003), EMBASE (1974 to November 2002), LILACS (1982 to January 2003), and reference lists of reviews, books, and trials. I handsearched journals, contacted researchers, funding agencies, and net and insecticide manufacturers.

Selection criteria
Individual and cluster randomized controlled trials of insecticide-treated bed nets or curtains compared to nets without insecticide or no nets. Trials including only pregnant women were excluded.

Data collection and analysis
The reviewer and two independent assessors reviewed trials for inclusion. The reviewer assessed the risk of bias in the trials, and extracted and analysed data.

Main results
Fourteen cluster randomized and eight individually randomized controlled trials met the inclusion criteria. Five trials measured child mortality: ITNs provided 17% protective efficacy (PE) compared to no nets (relative rate 0.83, 95% confidence interval (CI) 0.76 to 0.90), and 23% PE compared to untreated nets (relative rate 0.77, 95% CI 0.63 to 0.95). About 5.5 lives (95% CI 3.39 to 7.67) can be saved each year for every 1000 children protected with ITNs. In areas with stable malaria, ITNs reduced the incidence of uncomplicated malarial episodes in areas of stable malaria by 50% compared to no nets, and 39% compared to untreated nets; and in areas of unstable malaria: by 62% for compared to no nets and 43% compared to untreated nets for Plasmodium falciparum episodes, and by 52% compared to no nets and 11% compared to untreated nets for P. vivax episodes. When compared to no nets and in areas of stable malaria, ITNs also had an impact on severe malaria (45% PE, 95% CI 20 to 63), parasite prevalence (13% PE), high parasitaemia (29% PE), splenomegaly (30% PE), and their use improved the average haemoglobin level in children by 1.7% packed cell volume.

Authors' conclusions
ITNs are highly effective in reducing childhood mortality and morbidity from malaria. Widespread access to ITNs is currently being advocated by Roll Back Malaria, but universal deployment will require major financial, technical, and operational inputs.

Insecticide‐treated bed nets and curtains for preventing malaria

This report updates and combines earlier versions of guidelines for the prevention and treatment of opportunistic infections (OIs) in HIV-infected adults (i.e., persons aged >/=18 years) and adolescents (i.e., persons aged 13--17 years), last published in 2002 and 2004, respectively. It has been prepared by the Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and the HIV Medicine Association (HIVMA) of the Infectious Diseases Society of America (IDSA). The guidelines are intended for use by clinicians and other health-care providers, HIV-infected patients, and policy makers in the United States. These guidelines address several OIs that occur in the United States and five OIs that might be acquired during international travel. Topic areas covered for each OI include epidemiology, clinical manifestations, diagnosis, prevention of exposure; prevention of disease by chemoprophylaxis and vaccination; discontinuation of primary prophylaxis after immune reconstitution; treatment of disease; monitoring for adverse effects during treatment; management of treatment failure; prevention of disease recurrence; discontinuation of secondary prophylaxis after immune reconstitution; and special considerations during pregnancy. These guidelines were developed by a panel of specialists from the United States government and academic institutions. For each OI, a small group of specialists with content-matter expertise reviewed the literature for new information since the guidelines were last published; they then proposed revised recommendations at a meeting held at NIH in June 2007. After these presentations and discussion, the revised guidelines were further reviewed by the co-editors; by the Office of AIDS Research, NIH; by specialists at CDC; and by HIVMA of IDSA before final approval and publication. The recommendations are rated by a letter that indicates the strength of the recommendation and a Roman numeral that indicates the quality of evidence supporting the recommendation, so that readers can ascertain how best to apply the recommendations in their practice environments. Major changes in the guidelines include 1) greater emphasis on the importance of antiretroviral therapy for the prevention and treatment of OIs, especially those OIs for which no specific therapy exists; 2) information regarding the diagnosis and management of immune reconstitution inflammatory syndromes; 3) information regarding the use of interferon-gamma release assays for the diagnosis of latent Mycobacterium tuberculosis (TB) infection; 4) updated information concerning drug interactions that affect the use of rifamycin drugs for prevention and treatment of TB; 5) the addition of a section on hepatitis B virus infection; and 6) the addition of malaria to the list of OIs that might be acquired during international travel. This report includes eleven tables pertinent to the prevention and treatment of OIs, a figure that pertains to the diagnois of tuberculosis, a figure that describes immunization recommendations, and an appendix that summarizes recommendations for prevention of exposure to opportunistic pathogens.

Guidelines for prevention and treatment of opportunistic infections in HIV-infected adults and adolescents: recommendations from CDC, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America.

The first edition of this reference work was published in 1898, and the last update was published in 1972. This current edition is written by six major contributors and contains either rewritten or new chapters, including one 29-page chapter entitled "Ophthalmology in the Tropics" by F. C. Rodger, MD. Not only is this material valuable to physicians in endemic areas, but it is also important for travelers to the tropics who may return home with these diseases. Most of the chapters discuss the following aspects of tropical disease: cause, transmission, immunology, epidemiology, geographical distribution, pathologic condition, clinical findings, and diagnosis (including laboratory findings, treatment, and prevention). Beside chapters on infections, there are chapters on disorders due to heat, nutritional diseases, and venoms and poisons, and appendices on protozoology, helminthology, entomology, and clinical pathologic conditions. Excellent illustrations of end-stage pathologic conditions are disconcerting. Ophthalmologists would be most interested in the discussion

Manson's Tropical Diseases

Rates of acquisition and loss of parasitic infection in the vector host of Wuchereria bancrofti were estimated using a new method. The age of parasitic infections was estimated from the abdominal condition, determined on the basis of Sella's stages of blood digestion and ovary development, and parity of the vector host and larval stages of the parasite. A negative exponential relationship between age and number of W. bancrofti infections provided estimated daily losses of 25.3% and 33.2% of the initial infection from the resting and biting populations, respectively, of the mosquito Culex quinquefasciatus. The rates per day of acquisition of infection estimated from resting and biting female Cx. quinquefasciatus were found to be 9.6% and 8.6%, respectively. The mean minimum developmental time for W. bancrofti infective larvae estimated from the natural resting and biting populations were 8.9 +/- 1.41 (+/- SEM) and 8.33 +/- 0.85 days, respectively, which was somewhat less than the duration observed under laboratory conditions. Comparisons of the estimates (mean age, rates of acquisition, and loss of infections) based on the resting and biting data suggest that the rates are independent of the method of collecting mosquitoes.

Rates of acquisition and loss of Wuchereria bancrofti infection in Culex quinquefasciatus.

Current programmes to eliminate lymphatic filariasis (LF) are largely based on annual mass administrations of single doses of antifilarial drugs. The level and pattern of compliance by the target population are important determinants of the success of such mass drug administrations (MDA). Community compliance was therefore investigated during a study in southern India of the effects, on Wuchereria bancrofti microfilaraemia and transmission, of spaced MDA based on diethylcarbamazine (DEC) or ivermectin (IVM). During six rounds of MDA, the frequency of compliance in the target populations, in the five study villages given DEC and the five given IVM, ranged from 55%-77%. Analysis of the relevant cohort data indicated that about 30% of the villagers had complied with treatment during all six rounds, but 3.5% of those in the DEC arm and 4.0% of those in the IVM arm had never complied with treatment. Most of the villagers (>90%) had received treatment at least once, however, and >60% had each received treatment in at least four of the six rounds. Overall, there was a significant negative correlation (r=-0.78; P=0.008) between the size of the village, in terms of the number of villagers, and the mean frequency of compliance over the six rounds of MDA. The pattern of community compliance was found to be 'semi-systematic', laying between random and systematic. In terms of the elimination of LF, a semi-systematic pattern of compliance is worse than random compliance but better than systematic. The relevance of the levels and patterns of compliance to LF control or elimination is discussed.

Pattern of community compliance with spaced, single-dose, mass administrations of diethylcarbamazine or ivermectin, for the elimination of lymphatic filariasis from rural areas of southern India.

Hospital acquired enteric infections were investigated by studying 3138 children under 5 years of age who were admitted without diarrhea in nine medical words of a pediatric hospital, Calcutta during the period between March and September 1987. Three hundred and twenty (10.2%) children developed nosocomial diarrhea during their hospital stay. Fecal samples from 178 nosocomial diarrhea, 345 hospitalized diarrhea cases, 178 hospital controls and 200 outpatient controls were collected for detection of established enteropathogens. There were no statistically significant differences in the detection of most of the enteropathogens from fecal samples of nosocomial diarrhea, hospitalized diarrhea and hospital controls. Enteric pathogens were detected at a higher frequency (statistically significant) from fecal samples of nosocomial diarrhea cases as compared to outpatient controls. This study highlights the importance of most of the enteropathogens like Shigella, Salmonella, rotavirus, enteropathogenic E. coli as the cause of hospital cross infection. This study reinforces the importance of developing preventive measures in order to reduce the frequency of illness.

Prospective study of nosocomial enteric infections in a pediatric hospital, Calcutta.

The choice of drugs for the treatment of visceral leishmaniasis (VL) during pregnancy has to be made with particular care, to avoid damaging the foetus. The most commonly used antileishmanial drugs, sodium antimony gluconate (SAG) and pentamidine, may have some teratogenicity (Thakur et al., 1993a). Marsden (1985) described how a pregnant woman treated with pentavalent antimony delivered a mentally retarded child. Most general textbooks on infectious disease fail to discuss the problems of treating VL in pregnancy, and there have been few published studies on this topic (Sainani, 1991). The aim of the present study was to explore the use of amphotericin B in the treatment of pregnant women with VL, as this drug has proved to be more efficacious and better tolerated than SAG (Thakur, 1992; Thakur et al., 1993a, b). At the Rajendra Memorial Research Institute of Medical Sciences (RMRIMS), in Patna, India, four pregnant women, at different stages of gestation, were confirmed to have VL when amastigotes were detected in splenic aspirates or promastigotes were found in a culture of a bone-marrow aspirate (see Table 1). Each woman was treated with 15 infusions of amphotericin B, at a dose of 1 mg/kg in each infusion, given on alternate days. The women’s clinical and haematological characteristics and blood biochemistry and the condition of their foetuses were explored before treatment, in mid treatment and at the end of treatment (Table 2). At

Visceral leishmaniasis in pregnancy — the role of amphotericin B

The excretory-secretory antigens collected from the axenic culture medium and conventional somatic antigen prepared from the whole trophozoites of E. histolytica were compared for their efficacy in serodiagnosis of amoebiasis. A total of 280 sera collected from different clinically proven cases of amoebiasis and healthy subjects were analysed against both the antigens in ELISA. Both antigens showed a 100 per cent correlation in amoebic liver abscess cases, patients infected with enteropathogens other than amoeba and healthy subjects. However, excretory-secretory antigens showed slightly higher detection rate in patients suffering from acute amoebic dysentery and asymptomatic cyst passers groups. These results clearly suggested the use of excretory-secretory antigens by ELISA for serodiagnosis of amoebiasis due to its better or equal sensitivity, specificity and easier preparation compare to conventional antigen. The use of excretory-secretory antigen in serodiagnosis will not only help in performing more tests utilizing the same chemicals, but also save the cost, time and troubles for importing the foreign chemicals required for cultivation of E. histolytica.

P. K. Das

Papers

Rates of acquisition and loss of Wuchereria bancrofti infection in Culex quinquefasciatus.

Pattern of community compliance with spaced, single-dose, mass administrations of diethylcarbamazine or ivermectin, for the elimination of lymphatic filariasis from rural areas of southern India.

Prospective study of nosocomial enteric infections in a pediatric hospital, Calcutta.

Visceral leishmaniasis in pregnancy — the role of amphotericin B

Comparative evaluation of somatic & excretory-secretory antigens of Entamoeba histolytica in serodiagnosis of human amoebiasis by ELISA.