The reservoir of Plasmodium falciparum malaria in a holoendemic area of western Kenya.

The reservoir of infectious Plasmodium falciparum gametocytes in a population living in an area of holoendemic malaria in western Kenya was estimated by directly feeding mosquitoes on volunteers. Resulting mosquito infections were assessed both by midgut examination for oocysts and by enzyme-linked immunosorbent assay for P. falciparum circumsporozoite antigen. Calculations based on the age structure of the population and the resulting rates of mosquito infections indicated that children under 10 years of age were responsible for 72% of mosquito infections, individuals between 10 and 21 years of age contributed 12%, and those over 21 years of age accounted for 16%. No infection resulted in mosquitoes fed on infants less than 1 year of age.     

Plasmodium-specific immunoglobulin E in sera from an area of holoendemic malaria

Serum samples obtained from adults living in an area of holoendemic malaria in Papua New Guinea and from control residents of Hawaii were tested for Plasmodium-specific immunoglobulin (Ig) E antibody by the enzyme-linked immunosorbent assay. Fifteen (33.3%) of the New Guinea sera had absorbance values indicative of seropositivity. Only half of the IgE-positive sera were concomitantly positive for antimalarial IgG antibody. All of the control sera were negative for antibody of both immunoglobulin classes.     

Bancroftian filariasis in a Philippine village: clinical, parasitological, immunological, and social aspects.

The distribution and effects of Bancroftian filariasis in 535 inhabitants of a Philippine village were investigated. Clinical, parasitiological, immunological, and socioeconomic assessments were made. A history of acute lymphatic inflammation and the presence of inguinal lymphadenopathy were common. Lymphatic obstructive disease, defined as leg edema, hydrocele, or an epididymal cyst, was more common in men than women and increased progressively with age. The prevalence and intensity of microfilaremia rose with age in males, whereas the prevalence but not the intensity of infection increased with age in females. The prevalence of immunological responsiveness, as assessed by skin reactivity to microfilarial antigen and serum antibodies to adult filarial worms, increased with age in both males and females. There was no relationship between either microfilaremia or obstructive disease and the ability to work or have children, but both were more common in heads of households with the lowest socioeconomic scores. Epidemiological factors which may have contributed to these findings are discussed. (author's modified)     

Some aspects of traditional birth attendants' practice in a rural area in Tanzania.

As a pre-intervention study to improve the safety of the practice of traditional birth attendants, all 29 attendants in one rural area in Tanzania were interviewed, using a pre-tested questionnaire seeking information on the instruments used, care of the umbilical cord, and how they dealt with problem cases. The results are presented and discussed in this paper.     

Plague foci in Viet Nam: zoological and parasitological aspects.

Reported are the results of studies over the period 1989-94 on host-flea complexes in small mammals and their flea ectoparasites in and around a number of human settlements in Viet Nam in which human cases of plague had been found. Collections were also made in savanna and tropical forest areas within a 10-km radius of the settlements. The greatest numbers of small mammals, for the most part Rattus spp., and of the flea ectoparasite Xenopsylla cheopis were found in inhabited areas. X. cheopis was not found on any feral or sylvan mammal further than 0.6 km from settlements. A possible link between wild and commensal mammals may be provided by the flea Lentistivalius klossi, a specific parasite of squirrels and tree-shrews but also found in very small numbers on commensal rats. No zoonotic foci of plague were found in the immediate vicinity of the villages studied and it is most likely that plague persists in a commensal rat-X. cheopis cycle in and around human settlements in Viet Nam.     

The epidemiology of febrile malaria episodes in an area of unstable and seasonal transmission

This study investigated the epidemiology of uncomplicated falciparum malaria in an area of unstable and seasonal transmission in eastern Sudan. About 90% of malaria morbidity in this region occurs in the months of September to November, and very few malaria cases occur during the intensely arid Sudanese dry season and during years of drought. The malaria situation in the study site, the village of Daraweesh, was analysed during 3 consecutive malaria seasons in 1993-95 during which the 457 inhabitants suffered at total of 436 episodes of falciparum malaria. Using an Andersen-Gill proportional hazard model for recurrent events stratified by family, we have calculated the relative hazard for clinical malaria episodes by age, sex, haemoglobin genotype, blood type and infection in the previous season. The malaria risk was significantly lower in individuals aged 20-88 years than in the 5-19 years age-group. The relative protection due to adulthood varied between seasons (relative risk, RR, 0x34 to 0x67). Serological data were not consistent with the hypothesis that the age difference in incidence was due to differences in exposure. During the 1993 season the malaria incidence in males was lower than in females (RR = 0x75), during the 1994 season the incidences were comparable, whereas males had an increased risk of malaria in 1995 (RR = 1x87). The relative risk in individuals carrying the haemoglobin AS genotype compared to homozygous AA individuals was 0x57.     

Evaluation of lambdacyhalothrin-impregnated bednets in a malaria endemic area of India. Part 3. Effects on malaria incidence and clinical measures

In Indian villages with high malaria endemicity use of nylon bednets treated at 25 mg/m2 at 6-month intervals for 3 years caused significant reductions in malaria incidence, slide positivity rate, slide falciparum rate, annual parasite index, and parasite rate in the entire population, as well as reductions in rates of splenomegaly and anemia in children. In villages with untreated nets, considerable reduction also occurred in these parameters except for the rate of splenomegaly. In the village without nets, a relatively small drop occurred in the parasite rate and anemia but no change occurred in malaria incidence, and an increase occurred in the rate of splenomegaly. The trial thus showed the efficacy of impregnated bednets against malaria in the forested hills of Orissa State where the existing control strategy based on indoor residual spraying of DDT has remained incapable of interrupting malaria transmission.     

The clinical and parasitological presentation of Plasmodium falciparum malaria in Uganda is unaffected by HIV-1 infection

The relation between Plasmodium falciparum malaria and symptomatic human immunodeficiency virus 1 (HIV-1) infection was investigated in paediatric and adult patients in Kampala, Uganda, from 1987 to 1989. Both infections contributed largely to hospital morbidity. Of 1527 clinically suspicious in-patients, 61% were positive for HIV-1 infection. 52% of patients with positive HIV-1 serology fulfilled the World Health Organization clinical case definition for acquired immune deficiency syndrome (AIDS) in Africa. No association could be found between HIV-1 infection and malaria either in paediatrics or in adults. P. falciparum parasitaemia was present in 18% of all patients and no differences in prevalence of malaria infection or in parasite density could be demonstrated between HIV-1 positive and HIV-1 negative patients. The comparison of clinical symptoms showed typical differences in AIDS-related morbidity but no difference in malaria-specific morbidity. Also, the response to malaria treatment was the same in HIV-1 positive and HIV-1 negative patients. P. falciparum malaria does not appear to act as an opportunistic agent in AIDS patients in Uganda.     

Occupational lead poisoning in the United States: clinical and biochemical findings related to blood lead levels.

Dose-response relationships between blood lead levels and toxic effects have been evaluated in 160 lead workers in two smelters and a chemicals plant. Blood lead levels ranged from 0.77 to 13.51 mumol/litre (16-280 microgram/dl). Clinical evidence of toxic exposure was found in 70 workers (44%), including colic in 33, wrist or ankle extensor muscle weakness in 12, anaemia (Hgb less than 8.69 mumol/litre (Hb/4) or 14.0 gm/dl) in 27, elevated blood urea nitrogen (greater than or equal to 7.14 mmol/litre or 20 mg/dl) in 28, and possible encephalopathy in two. No toxicity was detected at blood lead levels below 1.93 mumol/litre (40 microgram/dl). However, 13% of workers with blood lead levels of 1.93 to 3.81 mumol/litre (40-79 microgram/dl) had extensor muscle weakness or gastrointestinal symptoms. Anaemia was found in 5% of workers with lead levels of 1.93-2.85 mumol/litre (40-59 microgram/dl), in 14% with levels of 2.90 to 3.81 mumol/litre (60-79 microgram/dl), and in 36% with levels greater than or equal to 3.86 mumol/litre (80 microgram/dl). Elevated blood urea nitrogen occurred in long-term lead workers. All but three workers with increased blood urea nitrogen had at least four years occupational lead exposure, and nine had received oral chelation; eight of this group had reduced creatinine clearance, and eight had decreased renal concentrating ability. These data support the establishment of a permissible biological limit for blood lead at a level between 1.93 and 2.90 mumol/litre (40-60 microgram/dl).     

Age-dependent occurrence of protective anti-Plasmodium falciparum sporozoite antibodies in a holoendemic area of Liberia

Antibodies to Plasmodium falciparum sporozoites were detected in children aged 6 months to 9 years, and in adults, in a holendemic village near Yekepa, Liberia, by enzyme linked immunosorbent assay (ELISA) using the recombinant circumsporozoite protein R32tet32 or by inhibition of sporozoite invasion (ISI) of hepatoma cells. Both assays were significantly correlated with each other and showed that anti-sporozoite antibodies increase with age. ISI was more sensitive than ELISA and demonstrated significantly increased anti-sporozoite antibodies at age 5-6 years, when young children show partial clinical resistance to malaria. These results suggest that anti-sporozoite antibodies, as measured by ISI, may contribute to protection against malaria.     

Urinary schistosomiasis in schoolchildren on Zanzibar Island (Unguja), Tanzania: a parasitological survey supplemented with questionnaires

The distribution of urinary schistosomiasis in schoolchildren on Zanzibar Island (Unguja) was surveyed in May 2001 to test a potential correlation with the distribution of snail species of the Bulinus africanus group and to record contemporary baseline epidemiological data. Quasi-random samples of 40 schoolchildren of mixed sexes were selected from each of 10 schools. Schistosoma haematobium infections were detected upon the basis of micro-haematuria with subsequent confirmation by microscopy examination for schistosome eggs. At the time of urine collection, each child was interviewed with a suite of 12 questions prepared as a standardized questionnaire. Total prevalence of urinary schistosomiasis (known locally as kichocho) was 12% although schistosome infections were absent in 5 schools. Schools located west of 39 degrees 19'E and north of 6 degrees 10'S harboured nearly all of the infections; the highest prevalence (55%) was found at Kinyasini where many B. globosus habitats occur nearby. The general level of understanding of kichocho was low (24%) and individual self-diagnosis was poor (sensitivity, 8.5%; specificity, 85%). Grouped freshwater-contact patterns of schoolchildren differed significantly between schools and correlated well with prevalence of infections within schools. Across the island the area of active transmission of S. haematobium to humans appears confined within the distribution of B. globosus. There was no epidemiological evidence to suggest any involvement of B. nasutus in local transmission, confirming previous laboratory findings. In areas where B. globosus occurs, targeted snail control should be considered, to reduce schistosome transmission.     

Current status of bancroftian filariasis in rural communities of the lower cross river basin,Nigeria: parasitological and clinical aspects

Background and objectives  There is a dearth of information on the geographical distribution of bancroftian filariasis in Africa on which to establish elimination programmes. The aim of this study is to assess the prevalence and density of microfilaraemia and the prevalence of clinical manifestations of bancroftian filariasis in six rural communities of Lower Cross River Basin, Nigeria. Methods  A total of 829 finger prick blood smear samples were collected from volunteers between 22.00 and 02.00 h and were examined for presence of helminth parasite Wuchereria bancrofti using standard parasitological method of diagnosis. All the volunteers were also screened for clinical manifestations of lymphatic filariasis. Results  Forty-six (5.6%) of the 829 samples collected were found to be microscopically positive for W. bancrofti. The prevalence of microfilaraemia was significantly (P<0.05) higher in females (8.4%) than males (3.6%). There is a significant variation (P<0.05) in the age-specific prevalence, with the age group 41–60 years being the most affected (10.2%). The overall geometric mean microfilarial density of the infected persons was 9 mf/50 μl. It was higher in males (11 mf/50 μl) than females (7 mf/50 μl) (P>0.05). The prevalence of infection and geometric mean density showed large variations; there was a trend towards increasing prevalence and density with increase in age in both sexes. The overall disease prevalence was 9.2%; the most important clinical manifestation was hydrocele (10.5%) and lymphoedema (2.9%). These chronic disease manifestations increased with age (P<0.05). Conclusion  These baseline data would be useful in planning for the elimination of lymphatic filariasis in Africa as per the WHO goal to eliminate lymphatic filariasis by the year 2020.     

Effect of meteorological factors on clinical malaria risk among children: an assessment using village-based meteorological stations and community-based parasitological survey

Background  

Temperature, rainfall and humidity have been widely associated with the dynamics of malaria vector population and, therefore, with spread of the disease. However, at the local scale, there is a lack of a systematic quantification of the effect of these factors on malaria transmission. Further, most attempts to quantify this effect are based on proxy meteorological data acquired from satellites or interpolated from a different scale. This has led to controversies about the contribution of climate change to malaria transmission risk among others. Our study addresses the original question of relating meteorological factors measured at the local scale with malaria infection, using data collected at the same time and scale.     

Sociomedical aspects of malaria control in Colombia.

A household interview survey combined with a serological survey on the incidence of malaria attacks and prevalence of antibodies has been carried out in rural and urban areas of the pacific coast of Colombia. Additional information on people's knowledge, attitudes and behaviour towards malaria was collected by means of participant observation and informal interviews. The results show that people incorporate modern and traditional elements into their concepts of the disease and treatment strategies. The deficiencies of the official control programmes are shown from the people's point of view. Some human factors which influence malaria transmission are discussed and an estimate of the accuracy of self-diagnosis presented.     

Nutrition modulation of gastrointestinal toxicity related to cancer chemotherapy: from preclinical findings to clinical strategy

Chemotherapy‐induced gut toxicity is a major dose‐limiting toxicity for many anticancer drugs. Gastrointestinal (GI) complications compromise the efficacy of chemotherapy, promote overall malnutrition, aggravate cancer cachexia, and may contribute to worsened prognosis. The GI tract is an attractive target for nutrition modulation, owing to its direct exposure to the diet, participation in uptake and metabolism of nutrients, high rate of cell turnover, and plasticity to nutrition stimuli. Glutamine, ω‐3 polyunsaturated fatty acids, and probiotics/prebiotics are therapeutic factors that potentially modulate GI toxicity related to cancer treatments. Preclinical and clinical evidence are reviewed to critically define plausible benefits of these factors and their potential development into adjuncts to cancer chemotherapy. Mechanisms underlying the action of these nutrients are being unraveled in the laboratory. Optimal strategies to translate these findings into clinical care still remain to be elucidated. Key questions that remain to be answered include the following: which nutrient or combination of nutrients is selected for which patient and chemotherapy regimen? What mechanisms are responsible for modulation, and how are nutrient(s) administered in a clinically optimal manner? Research exploring interactions between different nutrients in GI protection is ongoing and demands further understanding. How nutrition preparations given to chemotherapy‐treated patients are formulated in terms of component selection and dose optimization should be carefully studied and justified.     

Chronic clinical manifestations related to Wuchereria bancrofti infection in a highly endemic area in Kenya

Clinical examinations were conducted in an effort to provide baseline data for a pilot filariasis elimination programme implemented in a Wuchereria bancrofti-endemic focus in Malindi district, Kenya. Of 186 males aged 15 years and above examined, 64 individuals (34.4%) had hydrocele, and the prevalence of the manifestation in those above 40 years old was 55.3%. The prevalence of leg lymphoedema in persons aged 15 years and above was 8.5%, with a higher rate in males (12.6%) than in females (5.7%). The overall prevalence of inguinal adenopathy was 8.6%, and males had a significantly higher (12.9%) prevalence of adenopathy than females (5.1%) (P<0.001). The data in the present study provided support for consideration of filarial infection as a possible cause of inguinal lymphadenopathy in bancroftian filariasis-endemic areas. The results of this study also indicate that lymphatic filariasis is a serious public health problem in the northern coastal areas and morbidity control programmes should be implemented to alleviate the suffering of those affected.