5 research outputs found
Geophagy As A Risk Factor For Helminth Infections In Pregnant Women In Lusaka, Zambia
Get PDFIt has been reported that geophagy is closely associated
with helminthic diseases (1, 2, 3) and it has been especially
linked to Ascaris and Trichuris infections among pregnant women (4). Hitherto proof of existence of viable infective ova in geophageal material has been anecdotal. This study was undertaken to determine the possible direct role of geophagy in helminthiases of pregnant women. Eighty-five pregnant women between the ages of 15 and 44 years of age were recruited into the study in order to determined the prevalence of geophagy among pregnant women resident in high a density and low
income areas of Lusaka. The study showed that 31,8% of the pregnant women interviewed practised geophagy at the time of the study, and that 71% had a history of deliberate ingestion of soil. The preferences for the soil types were ranked as clay, termite mounds from tree trunks, and soft stone. Some respondents reported a preference for smoked, roasted or baked clay soils. Perceived benefits of geophagy included diminished craving when they ate soil ( 35.2% ), prevention of
vomiting and nausea ( 32.4% ), and others ingested soil for the taste (32.4% ). Most women who were interviewed
(91.8%) were aware of possible health risks involved in
geophagy such as constipation, heartburn, anemia, coughing, infections with worms, and abdominal discomfort.
This study sought to recover and identify helminth ova
from a total 3.15Kg. Submitted or collected soil types
ingested by the women in the study. No ova was
recovered from the soil samples by both the sedimentation and Zinc Sulphate, as well as saturated sodium chloride floatation techniques. These techniques reliably yielded Ascaris, Schistosome, and hookworm ova and Strongyloides larvae in spiked control specimens. Notably, Ascaris lumbricoides, and Trichuris trichiura ova require moisture to survive and embryonate. The soils ingested by the respondents were dried, some of which are roasted, backed or smoked before ingestion
and thus rendering them unsuitable for the survival of ova, let alone the support of embryonated ova which are the infectious stages. This study has demonstrated that no ova were recovered from any of the soil types preferred by the pregnant
women, and as such geophagy was an unlikely risk factor for geohelminth infections. Other explanations for the high helminth infection rates among pregnant women recorded in the literature must be sought, such as pica, poor hygiene, and unsanitary environments
Impacts of Bacillus thuringiensis var. israelensis and Bacillus sphaericus insect larvicides on mosquito larval densities in Lusaka, Zambia
Get PDFThe study assessed the impact of bio-larvicides- Bacillus thuringiensis var. israelensis (Bti) and B. sphaericus (Bs) on anopheline mosquito larval densities in four selected areas of Lusaka urban district. Larval densities were determined using a standard WHO protocol at each study area prior to and after larviciding. Ninety percent (90%) of the collected mosquito larvae and pupae were preserved in 70% ethanol, while 10% were reared to adults for species identification. Prior to larviciding, the largest number of mosquito larvae collected was culicines. Among the anophelines, Anopheles coustani Laveran (13.5%) (n = 111) and An. squamosus Theobald (9.5%) (n = 78) were identified from all the study areas with An. rufipes Gough (1.1%) (n = 9) collected from one study area only. None of the major malaria vector species reported for Zambia were identified. No mosquito larvae were found in freshwater bodies following the larviciding exercise. Possible reasons for the absence of known major malaria vectors could be the re-introduction of effective vector control and loss of suitable breeding grounds. The study highlights the potential of larviciding using Bti and Bs for malaria vector control and its integration with indoor residual spraying and insecticide treated nets
Resistance of a Rodent Malaria Parasite to a Thymidylate Synthase Inhibitor Induces an Apoptotic Parasite Death and Imposes a Huge Cost of Fitness
Get PDFBACKGROUND: The greatest impediment to effective malaria control is drug resistance in Plasmodium falciparum, and thus understanding how resistance impacts on the parasite's fitness and pathogenicity may aid in malaria control strategy. METHODOLOGY/PRINCIPAL FINDINGS: To generate resistance, P. berghei NK65 was subjected to 5-fluoroorotate (FOA, an inhibitor of thymidylate synthase, TS) pressure in mice. After 15 generations of drug pressure, the 2% DT (the delay time for proliferation of parasites to 2% parasitaemia, relative to untreated wild-type controls) reduced from 8 days to 4, equalling the controls. Drug sensitivity studies confirmed that FOA-resistance was stable. During serial passaging in the absence of drug, resistant parasite maintained low growth rates (parasitaemia, 15.5%±2.9, 7 dpi) relative to the wild-type (45.6%±8.4), translating into resistance cost of fitness of 66.0%. The resistant parasite showed an apoptosis-like death, as confirmed by light and transmission electron microscopy and corroborated by oligonucleosomal DNA fragmentation. CONCLUSIONS/SIGNIFICANCE: The resistant parasite was less fit than the wild-type, which implies that in the absence of drug pressure in the field, the wild-type alleles may expand and allow drugs withdrawn due to resistance to be reintroduced. FOA resistance led to depleted dTTP pools, causing thymineless parasite death via apoptosis. This supports the tenet that unicellular eukaryotes, like metazoans, also undergo apoptosis. This is the first report where resistance to a chemical stimulus and not the stimulus itself is shown to induce apoptosis in a unicellular parasite. This finding is relevant in cancer therapy, since thymineless cell death induced by resistance to TS-inhibitors can further be optimized via inhibition of pyrimidine salvage enzymes, thus providing a synergistic impact. We conclude that since apoptosis is a process that can be pharmacologically modulated, the parasite's apoptotic machinery may be exploited as a novel drug target in malaria and other protozoan diseases of medical importance
