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The diel oviposition periodicity of females of the LSHTM strain of Aedes aegypti was studied, under laboratory conditions, using one female/cage and monitoring, by changing the substrate, every 1, 2, 4 or 24 h. The individual females monitored at hourly intervals showed peak oviposition at 18.00–19.00 hours (a period when 44% of the eggs observed were laid) whereas the individuals monitored at two-hourly intervals showed peak oviposition between 16.00–18.00 hours (38% of eggs). The four-hourly monitoring gave a result that was similar to that of the two-hourly monitoring, with 79% of eggs laid between 14.00–18.00 hours, indicating an earlier peak in oviposition than seen with the one-hourly monitoring. Care should therefore be taken when conducting similar studies in the laboratory and when comparing or considering data derived from experiments in which different monitoring intervals have been employed. [ABSTRACT FROM AUTHOR]

Mathematical modelling has been used to assess the level of malarial transmission, during the dry season, in Nouna province, in north–western Burkina Faso. The data used were collected, at four sites (one semi-urban and three rural), from 867 children aged 6–60 months who were randomly selected. Almost all of the children (850) completed the follow-up, which involved the active detection of malaria (i.e. febrile, smear-positive malarial infection) throughout a single dry season (December 2003–May 2004). Light traps were used to sample the local populations of Anopheles vectors, in order to estimate the daily biting rate. The mathematical model was then used to simulate the incidence of malaria, which was compared with the observed incidence. At all four study sites, new cases of malaria were observed throughout the dry season, although the level of transmission was low. The monthly incidence of malaria estimated using the mathematical model was very close to the observed incidence. The fit was sensitive to daily mosquito survival and daily human parasite clearance. In Nouna province, effective interventions to prevent malaria should not be confined to the rainy season but must continue throughout the year. The focus should be on the clearance of parasitaemias, by the use of effective drugs, and on decreasing vector survival, by the use of vector-control methods. [ABSTRACT FROM AUTHOR]

The zoonotic liver flukes Fasciola hepatica and F. gigantica co-exist in parts of Africa and Asia. The two species have similar life-cycles but different transmission characteristics. Although the identification of adult Fasciola to species level is traditionally based on differences in size and shape, recent studies have demonstrated this method to be unreliable. Species of Fasciola can be distinguished by staining and comparing the morpho-anatomy of the gut and ovaries or by iso-enzyme analysis but such approaches are time-consuming and require specialist skills. Two primer sets, based on RAPD-derived sequences from English F. hepatica and Ghanaian F. gigantica, can now be used, in two separate PCR, to distinguish F. hepatica from F. gigantica. When the PCR were used to investigate 10 flukes (five from the U.K. and five from Peru) morpho-anatomically identified as F. hepatica and 10 (five from Ghana and five from Sudan) morpho-anatomically identified as F. gigantica, all 20 flukes were correctly identified to species level. The PCR were validated using 175 flukes collected, over a 12-year period, from different countries and both cattle and sheep. [ABSTRACT FROM AUTHOR]

In Ghana in 2004 (when choroquine was still the nationally recommended drug for the first-line treatment of malaria), the sensitivities, to chloroquine, amodiaquine, quinine, mefloquine, artesunate and halofantrine, of 60 Plasmodium falciparum isolates from two ecologically distinct areas of the country were assessed in vitro. The aim was to make available, to policy-makers, the field-based evidence needed to review the national strategy for malaria treatment. Drug susceptibilities were explored using the standardized protocol of the Antimalarial Drug Resistance Network. Although 32 of the P. falciparum isolates evaluated (56.1% of the 57 isolates successfully investigated for their susceptibility to choroquine) showed resistance to chloroquine and two showed slightly reduced sensitivity to amodiaquine, all the isolates were sensitive to mefloquine, artesunate, quinine and halofantrine. The median inhibitory concentrations (IC50) of chloroquine were positively correlated with those of quinine (r=0.4528; P=0.0008) but not those of any of the other drugs investigated. The IC50 of amodiaquine and artesunate were also positively correlated (r=0.3703; P=0.0067). These results provide evidence of the presence, in Ghana, of P. falciparum isolates that are highly resistant to chloroquine but generally sensitive to most of the other antimalarial drugs commonly used in the country. Partly in consequence of these observations, the recommended first-line treatment for malaria in Ghana was changed to an amodiaquine–artesunate combination in January 2005. [ABSTRACT FROM AUTHOR]

In filariasis-endemic areas beyond sub-Saharan Africa, the World Health Organization's recommended strategy for interrupting transmission of the causative parasites is annual, single-dose, mass treatment with a combination of diethylcarbamazine (DEC; given at 6 mg/kg) and albendazole (ALB; given at 400 mg) for 4–6 years (the minimum estimated life-span of the adult parasites). In an open, hospital-based, randomized and controlled trial, with a blinded evaluation of outcome, 82 children and adolescents from Recife, all with Wuchereria bancrofti microfilaraemias, were given either DEC alone (6 mg/kg) or the same dose of DEC combined with ALB (at 400 mg/patient). Every 90 days for 1 year after the single treatment, each patient was checked for microfilaraemia by the filtration of up to 5 ml of venous blood collected at night. One year post-treatment, 16 (39%) of the 41 patients given DEC alone and 20 (49%) of the 41 given DEC–ALB were found microfilaraemic (relative risk=0.8, with a 95% confidence interval of 0.49–1.31) and the corresponding geometric mean levels of microfilaraemia were 2.0% and 1.8% of the levels recorded immediately pre-treatment, respectively (P>0.05). In terms of the prevalences and intensities of microfilaraemia, therefore, the addition of ALB to the DEC appeared to offer no significant benefit. [ABSTRACT FROM AUTHOR]

Attempts have been made to transfer Wolbachia from infected to uninfected, laboratory-reared Phlebotomus papatasi, through mating, and to determine whether the incompatibility phenotype could be expressed through crosses between infected and uninfected flies. In order to test for the intraspecific transmission of Wolbachia in crosses between infected females and uninfected males, or those between uninfected females and infected males, a PCR based on Wolbachia -specific wsp primers was used to test the progeny of each cross and, subsequently, 50 individual flies from the F3 generation. All the individual flies tested from the F1 progeny of the crosses between infected males and uninfected females were found to be uninfected. In the crosses involving infected females and uninfected males, however, Wolbachia were found in the progeny of five matings out of the 23 that produced viable eggs. In the F3, Wolbachia were not detected in any of the individuals resulting from the cross between uninfected females and infected males but they were detected in 52% (26) of the 50 tested individuals resulting from the cross between infected females and uninfected males. No evidence of cytoplasmic incompatibility (CI) was observed in any of the crosses. The absence of CI expression and relatively low frequencies of maternal transmission could hamper the potential use of Wolbachia in a transgenic strategy for the control of leishmaniases. [ABSTRACT FROM AUTHOR]

In the Gurage zone of central Ethiopia, the association between fly density and the occurrence of trachoma has been investigated across varying altitudes. The seasonal pattern of fly density in the area was also explored. When, over short sampling periods (10 min/child indoors and 10 min/child outdoors), hand nets were used to collect flies from the eyes of children aged 2–8 years, only Musca sorbens and M. domestica were caught. Almost all of the 13,147 'eye-seeking' flies collected came from villages at low (<2000 m; 40.7%) or mid altitudes (2200–2500 m; 58.6%) with only 0.7% of them caught in the high-altitude villages investigated (at >3000 m). Musca sorbens predominated outdoors and M. domestica indoors. Almost all (99.3%) of the eye-seeking M. sorbens collected were caught outdoors whereas most (76.7%) of the M. domestica were caught indoors (P<0.0001 for each). The median numbers of flies caught, per child, per 10-min collection, in the low-, mid- and high-altitude villages were 9.5, six and zero, respectively, for M. sorbens, and eight, three and zero, respectively, for M. domestica. The altitudinal trends in these numbers of 'eye-seeking' flies matched those in the prevalences of active trachoma among children aged 1–10 years, which were high in the villages at low (81.6%) and mid altitude (78.7%) but much lower (1.7%) in the high-altitude villages. In conclusion, trachoma is a common disease of public-health importance only in the low- and mid-altitude villages in the Gurage zone, where there are large numbers of eye-seeking flies, and not in the villages that lie >3000 m above sea level, where there is a dearth of such flies. [ABSTRACT FROM AUTHOR]

It is possible to detect and distinguish Leishmania parasites using PCR-RLFP — a combination of PCR and analysis of the fragment-length polymorphism seen when the amplicons are digested with one or more restriction enzymes. In the present study, clinical samples from 24 Jordanians suspected to have cutaneous leishmaniasis and cultures set up using leishmanial parasites from five Greek dogs were investigated using PCR, in which the internal-transcribed-spacer-1 (ITS1) region of the parasites' ribosomal-RNA gene was amplified, followed by HaeIII digestion of the resulting amplicons. The cultures, which were all maintained in Leibowitz L-15 medium with 20% foetal calf serum, were each investigated as serial dilutions. Using the PCR-RLFP analysis, each culture was identified as L. donovani and each was found positive for this parasite with a mean sensitivity of 66%–100% (depending on the culture dilution tested), a specificity of 100%, a mean positive predictive value of 100%, and a negative predictive value of 74.6%–100%. When simulated clinical samples, created by mixing human blood with known numbers of L. donovani promastigotes, were investigated, the PCR-RFLP gave optimal results (with a value of 100% each for sensitivity, specificity and positive and negative predictive values). When the real clinical samples (25 lesion aspirates and 20 samples of peripheral blood from 24 Jordanian patients) were investigated using the molecular method, 20 (84%) of the patients were found to have lesion aspirates that were PCR-RFLP-positive for L. major (although, by microscopy, only six were found to have amastigote-positive lesion aspirates). None of the blood samples from the Jordanian patients, however, was found PCR-positive. [ABSTRACT FROM AUTHOR]

Although cercarial dermatitis is an emerging disease world-wide, cases of such dermatitis may often go undiagnosed, especially in communities that are affected by various skin infections. Between August 2001 and July 2002, 1336 individuals from tribal villages in central India were examined for dermatitis. Skin scrapings were collected and examined for Sarcoptes scabiei and each subject's response to antiscabies treatment was recorded. Freshwater snails were collected from the local ponds used for bathing, and examined for cercariae. The recorded prevalence of dermatitis ranged between 2.1% and 12.5% during the study year, peaking at the end of winter (February–March) and during the rainy season (August–October). Snail positivity for cercariae peaked in the rainy season. The prevalence and the severity of dermatitis were both higher in children than in adults. As most recorded cases of dermatitis were associated with a rash that developed soon after bathing in the local pond, all the skin scrapings were negative for itch mites, and the response to antiscabies treatment was poor, most if not all of the dermatitis observed was probably cercarial. Cercarial dermatitis therefore appears to be a significant health problem among the tribal populations of central India. [ABSTRACT FROM AUTHOR]

The article presents a study about the detection of Trypanosoma cruzi in Triatoma infestans. The primary aim of the study is to explore and compare the potential usefulness of polymerase chain reaction (PCR) and direct microscopical examination for detecting Trypanosoma cruzi infection in bugs used for xenodiagnosis.

The present study evaluated the efficacy and wash resistance of three types of commercial, deltamethrin-treated nets (PermaNetTM, YorkoolTM and A-Z nets) — that their manufacturers claimed to be long-lasting insecticidal nets (LLIN) — and those of nets conventionally treated with deltamethrin, at either 23–27 mg/m2 (using one K-O Tab H tablet/net) or 46–54 mg/m2 (using two K-O Tab tablets/net). The nets were tested unwashed or after being washed, by hand or machine, five or 15 times. After each wash, the nets were dried vertically on a line, in the shade, for 8 h. Insecticidal activity was assessed, using two types of bio-assay and wild-caught female Anopheles stephensi, as mean median knock-down times and as mortality 24 h after a 3-min exposure. For each type of nets tested, the insecticidal activity of the unwashed nets was greater than that of the nets washed five washes, and that of the nets washed five times was greater than that of the nets washed 15 times, with the latter decline considerably greater than the former. The pattern of decrease, however, differed with net type. The PermaNet and A-Z nets generally had the highest insecticidal activity, and, overall, the Yorkool nets did not perform significantly better than the conventional nets treated with 23–27 mg deltamethrin/m2. Although washing with detergents can clearly remove insecticide from the fibres of all types of treated nets, the consequent loss of activity varies with net type. After 15 washes, the PermaNet nets showed higher insecticidal activity than any other net type but there is still scope for the manufacturer of the PermaNet nets to improve wash resistance. [ABSTRACT FROM AUTHOR]

Eleven years after they had been given itraconazole or allopurinol for the treatment of chronic American trypanosomiasis, 109 adult patients were checked for electrocardiographic abnormalities and evidence of Trypanosoma cruzi infection. The parasitological investigations included xenodiagnosis, in which the faeces of Triatoma infestans that had fed on the patients were checked under the microscope for flagellates. In addition, a PCR-based assay and a hybridization assay were used to test blood samples from the patients, and faeces from the Tri. infestans that had fed on the patients, for Try. cruzi DNA. For the data analysis, the patients were divided into four groups known as normal/normal, abnormal/normal, normal/abnormal and abnormal/abnormal, according to whether the patients had been found to have normal or abnormal electrocardiograms (ECG) shortly before the first treatment and to have normal or abnormal ECG when checked at the 11-year follow-up. The 51 normal/normal and 24 normal/abnormal patients were assumed to have been in the 'indeterminate' phase of the disease when they were treated, whereas the 16 abnormal/normal and 18 abnormal/abnormal patients all had evidence of chagasic cardiopathy at that time. When checked 11 years post-treatment, 40 (78.4%), 17 (70.8%), 14 (87.5%) and 17 (94.4%) of these patients, respectively, were each found positive for Try. cruzi in at least one of the parasitological tests. The hybridization assay, whether applied to human blood or bug faeces, appeared a significantly more sensitive test than the PCR-based assays or microscopically assessed xenodiagnosis (P<0.05). Only the 21 patients who appeared to be negative for Try. cruzi could be considered parasitologically cured (although all still appeared to have anti-Try. cruzi antibodies in their blood). Only 13 of these parasitologically cured patients (seven of those treated with itraconazole and six of those given allopurinol) had normal ECG at the 11-year follow-up. In Chile at least, itraconazole, which caused fewer adverse effects than the allopurinol while being no less effective at preventing cardiopathy, appears to be the drug of choice to treat chronic American trypanosomiasis in adults. [ABSTRACT FROM AUTHOR]

The value of a direct agglutination test (DAT) in the detection of subclinical infections with Leishmania donovani has recently been investigated in the Indian state of Bihar, after the sensitivity and specificity of the test had been determined. When used to screen sera from 108 parasitologically confirmed cases of visceral leishmaniasis, 50 patients with active, non-leishmanial infection, and 641 healthy controls living close to, or distant from, an endemic area, the test was found to be 91.7% sensitive and 100% specific if a titre of 1 : 800 was used as the threshold for seropositivity. During a longitudinal clinical study in a rural, VL-endemic area of the Indian state of Bihar, the test was used, with 1 : 800 set as the threshold titre, to determine the baseline prevalence of infection with L. donovani among villagers who, though showing no symptoms of VL, had recently been febrile for at least 2 weeks. The 234 subjects of this study were either VL-case contacts [i.e. members of households in which there were active or cured VL cases (N=78)] or the members of control households with no cases or history of the disease (N=156). The results of DAT at the start of the study indicated that 49 (20.9%) of the subjects — 29 (37.2%) of the VL-case contacts and 20 (12.8%) of the other subjects — were seropositive and therefore probably had subclinical infections with L. donovani. During the subsequent 9 months of follow-up, however, only eight of the subjects found seropositive at the start of the study — seven (24.1%) of the seropositive case contacts but only one (5.0%) of the other seropositives — developed symptomatic VL, all by month 6 of the follow-up. Compared with their neighbours, therefore, individuals who shared households with active or cured cases of VL appeared at greater risk not only of L. donovani infection (indicating focal transmission) but also of developing symptomatic disease once infected. Curiously, among the seropositive case contacts, those from the households that harboured active cases of VL at the baseline survey were less likely to develop symptomatic VL during the 9 months of follow-up than those from households that harboured only cured cases (18.8% v. 30.8%). The wide-spread use of DAT could allow the detection and early treatment of latent L. donovani infections and so contribute to the elimination of VL, at least as a public-health problem, from India. [ABSTRACT FROM AUTHOR]

In a study of the phlebotomine sandflies (Diptera: Psychodidae) in a forest reserve in Recife, Pernambuco state, north–eastern Brazil, the sandflies landing on human bait between 1.00 and 1.42 h after sunset were collected weekly for 2 years. Although 10,287 sandflies of 10 Lutzomyia species were collected, almost all (96.5%) of the sandflies caught were Lu. umbratilis. This species and several others caught are potential vectors of some of the Leishmania parasites that cause human disease. The recorded landing rate for Lu. umbratilis peaked, at the high level of 333.3 flies/person-hour, during the collections made in May 2003. The relative rarity in the collections of males of some of the species caught probably indicates that these species do not lek on their bloodmeal sources. It is likely that the sizes of the local populations of species that are not very anthrophilic, such as Lu. flaviscutellata, are much larger than indicated by the collections made on human bait. [ABSTRACT FROM AUTHOR]

As a tick feeds, its saliva induces innate and acquired immune responses in the host, including leucocyte infiltration into the bite site. Tick salivary glands produce molecules, however, that counteract many host defences against blood feeding. The effects of salivary-gland extracts (SGE) of Dermacentor andersoni and Ixodes scapularis on the expression of various adhesion molecules [E-selectin, P-selectin, intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1)] by the sEND.1 cell line (which is based on cells from the subcutaneous tissue of mice) have now been investigated in vitro. The effects were found to differ with the tick species. The SGE of D. andersoni significantly down-regulated the expression of ICAM-1, whereas a similar extract prepared from I. scapularis significantly reduced the expression of P-selectin and VCAM-1. Tick salivary proteins therefore appear to have direct effects on adhesion-molecule expression, in addition to their previously established roles in down-regulating the pro-inflammatory cytokines that activate endothelial cells. It remains unclear exactly how the reduction of adhesion-molecule expression in the host's endothelial cells benefits the feeding tick but it may alter leucocyte migration to the bite site and/or reduce antigen presentation by the endothelial cells. It may also modulate the interactions between the host's leucocytes and any tick-borne pathogens, during initial infection of the endothelium. [ABSTRACT FROM AUTHOR]

This article discusses comparative effects of pyrimethamine-sulfadoxine, with and without probenicid, on Plasmodium falciparum gametocytes in children with acute, uncomplicated malaria. The article presents a study in this regard. The treatment of acute, Plasmodium falciparum malaria with pyrimethamine-sulfadoxine is often associated with drug-induced increases in the frequency of gametocyte carriage and the level of gametocytaemia. When pyrimethamine-sulfadoxine is used in combination with other antimalarial drugs, particularly with amodiaquine or the artemisinin derivatives, however, these unwelcome changes may be considerably reduced. The article further focuses on the study.

A cross-sectional study was conducted in tsetse-infested areas of Soroti district in Uganda, with the aim of assessing the response of the Nkedi Zebu and Ankole breeds of cattle to trypanosome infection. Overall, 1215 Nkedi Zebu and 260 Ankole cattle kept under similar levels of tsetse challenge were examined for trypanosome infection, using the Buffy-coat technique and haematocrit centrifugation, and had their packed-cell volumes (PCV) measured. As expected, the infected cattle, whether of the Nkedi Zebu (26.7% v. 29.6%; P<0.05) or Ankole breeds (24.9% V. 29.1%; P<0.05), had significantly lower mean PCV than the uninfected. In the Nkedi Zebu cattle, the prevalence of trypanosome infection was lower (7.9% v. 10.8%; P>0.05) and the overall mean PCV was significantly higher (29.4% v. 28.7%; P<0.05) than in the Ankole. Compared with the Ankole, Nkedi Zebu cattle appear to be less susceptible to (detectable) trypanosome infection and to the trypanosome-attributable lowering of their PCV. [ABSTRACT FROM AUTHOR]

When the larvae of Anopheles stephensi, a malaria vector, were selected with deltamethrin for 40 successive generations, there was a 60-fold increase in larval resistance to deltamethrin but no increase in the resistance of the adult mosquitoes. This result, and the observation that deltamethrin selection of adults for 40 generations resulted in only a six-fold increase in adult resistance to deltamethrin, indicated some stage specificity. When F24 deltamethrin-resistant larvae were selected with 1:5 deltamethrin-piperonyl butoxide (deltamethrin-PBO), instead of deltamethrin alone, for 16 generations, the level of resistance to deltamethrin in the F40 larvae was reduced by 6%-21%. Similarly, selection with deltamethrin-PBO of adults of the parental strain for 20 generations reduced the speed of the development of resistance to deltamethrin, compared with that seen using selection with deltamethrin alone. Deltamethrin selection appears to select initially a monooxygenase-based mechanism. When the monooxygenase-based mechanism is blocked, by treatment with PBO, selection of a kdr-type mechanism is accelerated; as is evident from increased cross-resistance to 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) in the adults selected with deltamethrin-PBO. The implications of these results are discussed in terms of the management of the larval and adult stages of An. stephensi. [ABSTRACT FROM AUTHOR]

As part of a larger study on the effects of permethrin-impregnated bednets on the transmission of Wucherena bancrofti, subjects from 12 villages in the Coastal province of Kenya, south of Mombasa. were investigated. The aims were to update the epidemiological data and elucidate the spatial distribution of IV hancrofti infection, Samples of night blood from all the villagers aged &ges; 1 year were checked for the parasite, and all the adult villagers (aged ? 15 years) were clinically examined for elephantiasis and, if male, lot hydrocele. Overall, 16.0% of the 6531 villagers checked for microfilariate (mff) were found microfilaraemic, although the prevalence at microfilaraemia in each village varied from 8. 1 %-27.4%. The geometric mean intensity of infection among the microfilaraemic was 322 mff/ml blood. At village level, intensity of the microfilaraemia was positively correlated with prevalence% indicating that transmission has a major influence on the prevalence of microfilaraemia. Clinical examination of 2481 adults revealed that 2.9% had elephantiasis of the leg and that 19.9% of the adult men (10.8%- 30.1% of the men invest i- gazed in each village) had hydrocele. Although the overall prevalence of microfilaracmia in the study villages had not changed much since earlier studies in the 1970s, both prevalence and intensity varied distinctly between the study villages. Such geographical variation over relatively short distances appears to he a common but seldom demonstrated feature in the epidemiology of bancroftian filariasis, and the focal nature of the geographical distribution should be carefully considered by those mapping the disease. [ABSTRACT FROM AUTHOR]

In Togo, chloroquine (CQ) remains the first-line drug for the treatment of uncomplicated, Plasmodium falciparum malaria. In the absence of recent data on the level of parasite resistance to antimalarial drugs, Togo's National Malaria Control Programme (NMCP) decided to assess the current efficacy of CQ in the treatment of uncomplicated, P. falciparum malaria at three sentinel sites in the north of the country. Between the September and November of 2001, the World Health Organization's standard 14-day protocol was used to investigate 153 malarious children aged 6-59 months old (46 from Sokode, 54 from Niamtougou and 53 from Dapaong). Of the subjects from Sokode, Niamtougou and Dapaong, early treatment failure was observed in 0%, 7% and 12%, late treatment failure in 0%, 11% and 17%, and overall parasitological failure in 0%, 45% [with a 95% confidence interval (CI) of 39%-51%] and 62% (CI=54%-70%), respectively. Even within northern Togo, there is clearly considerable geographical variation in the level of resistance to CQ. Before an efficient antimalarial-drug policy can be developed, there is an urgent need to develop and use the national surveillance system further, to collect relevant data on the efficacies of CQ and other antimalarial drugs, such as amodiaquine and sulfadoxine-pyrimethamine. [ABSTRACT FROM AUTHOR]

The clinical and parasitological features of visceral leishmaniasis (VL) were investigated, retrospectively, in 27 HIV-infected patients who attended the out-patient clinic of Catania University's Department of Infectious Diseases between 1990 and 1998. The aim was to evaluate the epidemiological, clinical, therapeutic and prognostic characteristics of the co-infection, to determine if there were any interactions between the two infections, and to see if the use of highly active antiretroviral therapy (HAART) had any impact on the leishmaniasis. The most dramatic observation was a marked, HAART-attributable reduction in the annual incidence of VL relapses among the patients. [ABSTRACT FROM AUTHOR]

Studies the chemotherapy of rodent malaria and the evaluation of blood schizontocidal activity in some endoperoxide antimalarials. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on studies of tropical medicine and parasitology.

Studies the potential applications of Origanum compactum as a cercaricide in Morocco. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on studies of tropical medicine and parasitology.

Studies the patterns of water-related disease before and after the construction of the Diama dam in northern Senegal. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on studies of tropical medicine and parasitology.

Studies the histopathology of bancroftian filariasis. Role of the adult worm in the lymphatic-vessel disease; Analysis of pertinent topics and relevant issues; Implications on studies of tropical medicine and parasitology.

Studies hepatitis C virus infections among intravenous-drug users in Thailand. Prevalence, genotypes and risk-factor-associated behavior patterns; Analysis of pertinent topics and relevant issues; Implications on studies of tropical medicine and parasitology.

Studies the tolerability, safety and pharmacokinetics of the co-administration of diethylcarbamazine and albendazole. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on studies of tropical medicine and parasitology.

Studies the effects of the mass administration of diethylcarbamazine, alone or with albendazole, on the prevalence of filarial antigenaemia. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on studies of tropical medicine and parasitology.

Studies the effects of chloroquine, amodiaquine and chloroquine plus chlorpheniramine on the disposition kinetics of the hepatomegaly associated with acute and uncomplicated Plasmodium falciparum malaria in children. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on studies of tropical medicine and parasitology.

The initial filling of the reservoir behind the Petit Saut hydro-electric dam, on the Sinnamary River in French Guiana, threatened the terrestrial and arboreal animals living in the neotropical rainforest being flooded. During a rescue programme between 24 October and 12 November in 1994, many of these animals were checked for infection with trypanosomatids. Overall, 45 blood samples and 54 skin biopsies were collected from 53 mammals (of 13 species representing five orders) and blood samples were also taken from each of nine reptiles (six species from four families). When the skin biopsies and the buffy-coats from the blood samples were cultured in NNN medium, 10 of the cultures, each initiated with mammalian blood, were found to be positive for trypanosomatids. Multilocus enzyme electrophoresis (MLEE) on cellulose acetate plates, with 20 enzyme systems, was then used to investigate each of the positive cultures. The results were analysed by clustering from a genetic distance matrix, using the unweighted pair group method with arithmetic averages (UPGMA), and applying a bootstrap procedure to Wagner parsimony trees. A stock obtained from Didelphis marsupialis was identified as a zymodeme of Trypanosoma cruzi (Miles' zymodeme 1) known to cause Chagas disease in French Guiana. Five stocks (one each from Bradypus tridactylus, Tamandua tetradactyla and Alouatta seniculus and two from Saguinus midas) were of a single zymodeme close to Trypanosoma rangeli reference stock RGB. This is the first confirmation of the presence of Tr. rangeli in French Guiana, and the first time that it has been identified, by iso-enzyme analysis, in the neotropical primates A. seniculus and S. midas. Two other stocks, isolated from Choloepus didactylus, were related to Endotrypanum schaudinni reference stock LEM 2790. Although the remaining stocks, one from C. didactylus and the other from A. seniculus, clustered together on UPGMA and in a Wagner tree, they did not appear to be related to any of the reference stocks included in the UPGMA dendrogram. [ABSTRACT FROM AUTHOR]

Examines the histopathological and parasitological changes in baboons with human and baboon-isolate infection of Schistosoma mansoni in Saudi Arabia. Discovery of inflammatory reactions in the infections; Role of baboons as reservoir hosts; Calculations on the number of granulomas.

The endemicity of cutaneous leishmaniasis (CL) caused by Leishmania tropica was ascertained in a focus of the disease around Eira and Yarqa in Salt District, Jordan. This focus is about 10 km to the east of another focus of CL, where L. major is the causative agent . As CL occurs sporadically in the study area, with nine cases diagnosed between 1993 and 1995, it is probably zoonotic. Each case had one or two lesions and most lesions were on the face. Isoenzymatic electrophoresis showed that all the parasites isolated in the Eira-Yarqa focus and identified to zymodeme level belonged to zymodeme MON-137 and therefore differed from all the L. tropica isolates identified in other regions of Jordan. Eight species of Phlebotomus ( P. alexandri , P. major , P. sergenti , P. papatasi , P. perfiliewi , P. jacusieli , P. canaaniticus and P. arabicus ), two members of the Sergentomyia dentata group and S. tiberiadis and S. taizi were collected in the focus, using castor-oil traps. The epidemiological significance of the sandflies collected is discussed. [ABSTRACT FROM AUTHOR]

Plasmodium falciparum is a eukaryotic single cell which invades human erythrocytes. Within the host cell, the parasite is surrounded by the membrane of the parasitophorous vacuole. Parasite proteins are secreted either into the vacuolar space or are exported, by an as yet unknown mechanism, across the vacuolar membrane into the erythrocyte cytoplasm. In recent years, several groups have devised experimental approaches to follow the transport pathways of proteins from the parasite into the host cell. The concepts underlying these approaches and the peculiarities of the transport pathways are discussed and compared with protein transport in higher eukaryotes. [ABSTRACT FROM AUTHOR]

The virulence of Plasmodium falciparum relative to the other species of malarial parasite which infect humans is thought to be due both to this parasite's ability to adhere to endothelial cells lining small blood vessels and, in some cases, to its ability to form rosettes with uninfected erythrocytes. The latter phenotype has been found more frequently in cases of severe disease. The former property means that only the younger, asexual, intra-erythrocytic forms circulate whereas the more mature developmental stages are sequestered in the vasculature of a variety of organs. When large numbers of parasites accumulate in a vulnerable target organ such as the brain, then the life-threatening condition of cerebral malaria may result. While the factors that control whether or not cerebral malaria develops are not clearly defined, one crucial determinant may be the endothelial receptors utilised by the infecting isolate. Many such receptors have been identified, including CD36, thrombospondin, ICAM-1, VCAM, E-selectin and chondroitin-4- sulphate. The results of laboratory, field, post-mortem and direct receptor-binding studies indicate that, of the receptors currently identified, ICAM-1 binding is most likely to be associated with the development of cerebral malaria. The molecule expressed on the surface of the infected erythrocyte which mediates adherence to endothelium belongs to a large family of clonally variable antigens encoded by the var genes. The evidence for this conclusion and progress in defining the regions of var -gene products responsible for receptorspecific binding are discussed. Finally, the organization of the var genes within and between parasites is discussed in relation to the evolution of the var -gene family and its functions of antigenic variation and endothelial adhesion. [ABSTRACT FROM AUTHOR]

Between 1984 and 1989, the onchocerciasis-vector control zone in the pilot area of San Vicente Pacaya, Guatemala, which had been subject to experimental control since 1979, was extended from 91.3 to 148.6 km2. Temephos was used as a larvicide against Simulium ochraceum s.l. the target species. As a new strategy, only breeding sites with water discharges of 0.1-10 litres/s were treated, every 2 weeks. This approach provided a substantial reduction in effort, number of treated sites, time and cost. To assess the effect of the temephos, nine sites were selected in which standardized collections of adult Simulium were made twice a month, by human bait. There was an obvious difference between the preand post-control mean densities of flies at each site. In the northern area, which includes the Lavaderos, Barretal, Colina and Rodeo sites, the biting density in 1979, before treatment, varied between 10 and 64 flies/man-hour (FMH). Four years later, this had been reduced to 0.1-3.2 FMH, and by the end of the present study, in 1989, the mean density was zero FMH. In the southern area, which lies south-east of Lavaderos (and includes Guachipilin, Ingerto, Pena Blanca and Sierra Morena), the density during the pre-control phase was 24 FMH at one of the two sites investigated at that time and 39.3 FMH at the other. It fell to 0.1-0.5 FMH after 5 years of control and to zero (three sites) or close to zero ( 0.5 FMH; one site) for the last 4 years of the present study. To assess the effect of vector control on onchocerciasis prevalence and incidence, 1280 residents from six endemic communities, out of 12 000 permanent inhabitants, were examined. In Santa Cruz, Patrocinio and Los Rios, the prevalence of skin microfilariae in the subjects from each community fell from 8.1%-37.8% during the pretreatment, base-line period to 0.0%-31.5% when the study foci were totally integrated into the vector-control operation following treatment. Incidence among children (aged 9 years) varied from 0%-25% for the period 1982-1984 but, thereafter, not a single case appeared in four of the six study communities (Santa Cruz, Patrocinio, Los Rios and Berlin). Incidence in Guachipilin did not decline appreciably, probably because of human migration into the area from other onchocerciasis foci. The prevalences of nodules followed a similar trend to those of the prevalence and incidence of skin microfilariae, falling from 9.1%-45.0% pre-control to 1.8%-14.3% 10 years later. [ABSTRACT FROM AUTHOR]

The first generation of malaria vaccines may not be effective enough to provide reliable protection against malaria for travellers to endemic areas. Nevertheless, these vaccines may be able to produce a useful degree of protection against death and severe morbidity from malaria in the populations of such areas. Pre-erythrocytic vaccines may provide this kind of protection by lengthening the prepatent period; blood-stage vaccines may achieve this effect by reducing parasitaemia. Because clinical immunity to malaria among residents of endemic areas reflects a complex balance between the parasite and its host, it is possible that partially effective vaccines could exert a harmful rather than a beneficial effect. Trials of malaria vaccines in the population of endemic areas must, therefore, progress with caution. [ABSTRACT FROM AUTHOR]

In 1993, Malawi introduced sulphadoxine-pyrimethamine (SP) for the treatment of uncomplicated, Plasmodium falciparum malaria and became the first country in Africa to abandon chloroquine for first-line therapy. This decision produced an urgent need to monitor local P. falciparum for resistance to SP and to establish both clinical and parasitological criteria for drug failure. The parasitological and haematological responses to treatment of malaria in southern Malawi with SP have now been investigated. Children, aged 6-59 months, who attended health-care facilities with uncomplicated infections of P. falciparum alone were enrolled in the study. Each received standard treatment with SP and paracetamol and was followed-up on days 3, 7, 14, 21 and 28 post-treatment. Haemoglobin (Hb) was measured on days 0, 14 and 28. Zinc erythroprotoporphyrin (ZP) was estimated once during follow-up, as an indicator of iron status. Of 107 children enrolled, 84 children (78.5%) were followed for 14 days or until clinical failure. The parasitological success rate amongst the latter was 90.5% (76/84). One child showed poor parasite clearance (with a parasitaemia at day 3 25% of that at day 0), one had a low level of persistent parasitaemia, and six were parasitaemic on day 14 after being parasite free on day 7. A 14-day follow-up increased the detection of parasitological failure by 7.2%. Haematological recovery on day 14 was not significantly different for parasitological successes or failures. The geometric mean parasite density (GMPD) was significantly lower in children classified as iron deficient (ZP 3.0 mg/g Hb) and these children were significantly more likely to be severely anaemic (Hb 8 g/dl) at day 0. Parasitological response and haemoglobin levels 28 days after SP treatment were independent of ZP levels. These results show that, 2 years after the introduction of SP in Malawi for the treatment of uncomplicated, P. falciparum malaria, the drug combination remains effective in 90.5% of cases. Iron status did not affect parasitological recovery. Although iron-deficient children were at greater risk of severe anaemia they did not show significantly reduced recovery from malarial anaemia. [ABSTRACT FROM AUTHOR]

The article presents a study that examines the rainfall and malaria transmission in north-eastern India. In this study, the association between rainfall and annual incidence of malaria in the country is being investigated. According to the study, the correlations observed between annual rainfall and malaria incidence were far too weak to be statistically significant.

A preface for the April 2006 issue of the "Annals of Tropical & Parasitology," is presented.

A foreword to "Annals of Tropical Medicine and Parasitology" is presented.

Presents books about tropical medicine and parasitology. 'The Behavioural Ecology of Parasites,' edited by E.E. Lewis, J.F. Campbell, and M.V.K., Sukhdeo; 'Macrocyclic Lactones in Antiparasitic Therapy,' edited by J. Vercruysse and R.S. Rew.

Reports on a new zymodeme of Leishmania tropica that is the causative agent of canine visceral leishmaniasis in northern Morocco. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on studies of tropical medicine and parasitology.

Presents corrections of articles in the 'Annals of Tropical Medicine & Parasitology' Volume 95 journal in July 2001. Transposition of the symbols in the legend; Calculations of monthly transmission potential; Administration of vector control.