Human water contact patterns in active schistosomiasis endemic areas.

One major risk factor common to individuals in schistosomiasis endemic areas is water contact patterns. Effort to determine the dynamics in water contact patterns in different regions needs utmost attention in order to suggest a better control strategy for schistosome infection. Quantitative observations on human water contact activities were recorded in Yewa North Local Government Area of Ogun State for a period of two years. Frequency and duration of observed water contact activities were recorded. Males had the highest water contact during the rainy season with 51.1% compared to females with 48.9%. Females had the highest water contact with 51.0% while males had 49.0% during the dry season. The age group 10-19 years had the highest water contact with 27.1%, this was followed by 20-29 years and 30-39 years age groups with 23.6% and 22.1%, respectively, during the rainy season. Our results showed that water contact activities differ with respect to different communities, sex and age groups. Previous high prevalence of schistosome infection in the study areas could be attributed to high water contact activities. Therefore, provision of adequate pipe-borne water, good sanitation and improved knowledge on schistosome life cycle among the community members will reduce the high rate of human water contacts.

Effects of low protein diet and pregnancy on course of Plasmodium berghei infection in mice.

Pregnancy and malnutrition influence the severity or trend of malaria especially in sub-Saharan Africa where parasitic infections are highly predominant. This study was used to evaluate the combined effects of low protein diet and pregnancy on the course of Plasmodium berghei infection in mice. Thirty female BALB/c mice were divided into six groups viz: Non-infected mice fed on normal diet (NIND), Infected mice fed on normal diet (IND), Noninfected mice fed on low protein diet (NILP), Infected mice fed on low protein diet (ILP), Non-infected gravid mice fed on low protein diet (NIGLP) and Gravid infected mice fed on low protein diet (GILP). Malaria parasite count, packed cell volume, body weight and plasma nitric oxide (NO) production were determined. Data were compared statistically across the groups using Student t-test and ANOVA. Parasite detection in peripheral blood was delayed in ILP (day 7) and GILP (day 11) relative to IND (day 3). The peak parasitaemia and mean survival time were significantly lower (p < 0.05) in GILP relative to other infected groups. GILP could not carry the pregnancy to term. Nitric oxide production was observed to increase more rapidly in IND relative to ILP after parasite detection with a peak production by day 15. Mortality commenced in both groups afterwards. Low protein diet delayed the peak production of NO supporting its protective influence on malaria infection. However, the combined effects of low protein diet and pregnancy resulted in early mortality and inability of mice to carry pregnancy to term.

Molluscicidal effect of Piper guineense.

The study was undertaken to assess the dosage-mortality ratio and toxic effects of Piper guineense fruit extracts on the adults of Biomphalaria pfeifferi, the snail intermediate host of Schistosoma mansoni, which causes intestinal schistosomiasis. The result showed significant toxic effects with crude ethanol and hot water fruits extracts. The estimated lethal dose concentration by arithmetic method (LC(50) and LC(90)) using both crude ethanol and hot water fruit media extracts were found to be (0.10 ± 0.04, 0.9 ± 0.2) mgl(-1) respectively for ethanolic extract and (5.0 ± 1.4, 8.5 ± 0.7) mgl(-1) respectively for hot water extract. Ethanolic extract was more potent than hot water extract. An all or none phenomenon appeared characteristic of the biological activity of these extracts. There was significant decrease in oviposition rate (p < 0.02). The extract from the fruits of this tropical plant holds promise in the control of Biomphalaria pfeifferi.

Knowledge, attitudes and practices about malaria in an urban community in south-western Nigeria.

BACKGROUND & OBJECTIVES: Oyo is an urban community in Oyo state of south-western Nigeria and it is holoendemic for malaria. Information was collected on the knowledge, attitudes and practices (KAP) of inhabitants of Oyo town in relation to malaria. METHODS: A cross-sectional survey of 192 households with the aid of self- or researcher-administered questionnaires was carried out to identify factors associated with the disease in the area. RESULTS: About 93.2% (n=192) of respondents recognized mosquito bites as the cause of malaria. A small proportion of children (13.7%) and adults (5.3%) received prompt treatment; however, more adults (65.8%) got correct dosage of antimalarials than children (38.7%). About 90% of suspected malaria cases in children and adults were first treated at home with local herbs or drugs, purchased from medicine stores. The use of insecticide-treated nets (ITNs) was scarce as only 16.7% of households used them for their children. Other reported malaria prevention methods include the use of insecticides (79.7%) and herbs (44.3%). In all, 17 (8.9%) of households did not have screening nets on their windows and 6.3% of 175 households with screening nets on their windows had rusty and torn nets. The level of education of heads of households was a strong predictor of positive malaria-related KAP. Window types and environmental hygiene were associated with prevalence of malaria in households. INTERPRETATION & CONCLUSION: The control of malaria cannot be achieved without full involvement of the affected communities; the available tools for control can only be effective and sustainable if the local communities are mobilized and empowered with knowledge. It is suggested that health education campaigns be intensified; chemist shop-keepers and mothers being important target groups.

Total immunoglobulin G and IgG1 subclass levels specific for the MSP-1(19) of Plasmodium falciparum are different in individuals with either processing-inhibitory, blocking or neutral antibodies.

BACKGROUND: Some MSP-1(19) specific antibodies that inhibit merozoite invasion also inhibit the secondary processing of MSP-1. However the binding of these inhibitory antibodies can be blocked by another group of antibodies, called blocking antibodies, which recognize adjacent or overlapping epitopes, but themselves have no effect on either MSP-1 processing or merozoite invasion. These antibodies have been reported to be present in individuals living in a malaria endemic area. METHODS: Blood samples were obtained from children shown to have processing inhibitory, blocking, and neutral antibodies in a previous study. Enzyme linked immunosorbent assay (ELISA), was used to determine the total IgG, IgM and IgG subtypes. RESULTS: There was a significant difference in anti-MSP-1(19) IgG, while there was no significant difference in the anti-MSP-1(19) IgM. Only anti MSP-1(19) IgG1, amongst the IgG subtypes was significantly different between the groups. CONCLUSION: This study shows that antibodies against MSP-1 are different not only in specificity and function but also in the amount of total IgG and IgG subtype produced.

Effect of antimalarial drugs and malaria infection on oxidative stress in pregnant women.

This work studied the effect of malaria infection and antimalarial drugs on oxidative stress in 259 pregnant and nonpregnant women at Ade-Oyo hospital, Ibadan, Nigeria. Oxidative stress was determined by measuring serum lipid peroxidation, ascorbic acid, and reduced glutathione (GSH) levels using spectrophotometer. The results showed that mean lipid peroxidation was significantly higher (p < 0.05) in malaria positive than malaria negative women, while GSH and ascorbic acid levels were significantly (p < 0.05) reduced. The parasite density was significantly reduced in patients who had taken antimalarial drugs relative to those without. While mean ascorbic acid and GSH levels were significantly reduced in those who had taken drugs as compared with those without drugs, the lipid peroxidation level was significantly higher in them. The increase in lipid peroxidation and decrease in GSH and ascorbic acid levels in women who were malaria positive and in those who had taken drugs is indicative of oxidative stress.

Total Immunoglobulin G and IgG1 Subclass Levels Specific for the MSP-1 19 of Plasmodium falciparum are Different in Individuals with either Processing-Inhibitory; Blocking or Neutral Antibodies

Background: Some MSP-1 19 specific antibodies that inhibit merozoite invasion also inhibit the secondary processing of MSP-1. However the binding of these inhibitory antibodies can be blocked by another group of antibodies; called blocking antibodies; which recognize adjacent or overlapping epitopes; but themselves have no effect on either MSP-1 processing or merozoite invasion. These antibodies have been reported to be present in individuals living in a malaria endemic area. Methods: Blood samples were obtained from children shown to have processing inhibitory; blocking; and neutral antibodies in a previous study. Enzyme linked immunosorbent assay (ELISA); was used to determine the total IgG; IgM and IgG subtypes.Results: There was a significant difference in anti-MSP-1 19 IgG; while there was no significant difference in the anti-MSP-1 19 IgM. Only anti MSP-1 19 IgG1; amongst the IgG subtypes was significantly different between the groups. Conclusion: This study shows that antibodies against MSP-1 are different not only in specificity and function but also in the amount of total IgG and IgG subtype produced

Effect of antimalarial drugs and malaria infection on oxidative stress in pregnant women

This work studied the effect of malaria infection and antimalarial drugs on oxidative stress in 259 pregnant and non-pregnant women at Ade-Oyo hospital, Ibadan, Nigeria. Oxidative stress was determined by measuring serum lipid peroxidation, ascorbic acid, and reduced glutathione (GSH) levels using spectrophotometer. The results showed that mean lipid peroxidation was significantly higher (p<0.05) in malaria positive than malaria negative women, while GSH and ascorbic acid levels were significantly (p<0.05) reduced. The parasite density was significantly reduced in patients who had taken antimalarial drugs relative to those without. While mean ascorbic acid and GSH levels were significantly reduced in those who had taken drugs as compared with those without drugs, the lipid peroxidation level was significantly higher in them. The increase in lipid peroxidation and decrease in GSH and ascorbic acid levels in women who were malaria positive and in those who had taken drugs is indicative of oxidative stress. (Afr. J. Reprod. Health 2010; 14[3]: 209-212)

The burden of malaria infection on pregnant women and birth weight of infants in south western Nigeria.

OBJECTIVE: To determine the effect of malaria infection on pregnant women and the birth weight of the infants in the south western Nigeria. SUBJECT: 262 pregnant women who came for antenatal clinic at Ade-Oyo maternity hospital. 128 were primigravidae while 134 were multigravidae. METHODOLOGY: 2ml of blood was withdrawn from 262 pregnant women who came for antenatal clinic at Ade Oyo maternity hospital. Thick blood smears were prepared for parasite identification and quantification. Anaemia was detected by measuring Hb levels using Drabkin's solution. Age, gravidity and history of treatment with antimalaria drugs were obtained from the subjects using questionnaire. RESULT: The overall prevalence of infection was 41.8%. Primigravidae were more infected (35%) than multigravidae (22%). The prevalence was significantly higher (p<0.05) in wet season than dry season. Teenagers and primigravidae were more infected than the adults and multigravidae. The severity of the anaemia was significantly higher (p<0.05) among malaria positive teenagers and primigravidae than adults and multigravidae. The mean birth weight of infants born to malaria positive was significantly lower (p<0.05) than those born to malaria negative mothers. Malaria positive teenagers and primigravidae had infants with lowest birth weight as compared with adult and multigravidae. The birth weights of the infants were positively correlated with the Hb levels. CONCLUSION: This study suggests that malaria infection, anaemia, and gravidity affect the birth weight of infants born in Ibadan, southwestern Nigeria.

Antibody specificities of children living in a malaria endemic area to inhibitory and blocking epitopes on MSP-1 19 of Plasmodium falciparum.

Merozoite surface protein-1(19) (MSP-1(19)) specific antibodies which include processing inhibitory, blocking and neutral antibodies have been identified in individuals exposed to Plasmodium falciparum. Here we intend to look at the effect of single and multiple amino acid substitutions of MSP-1(19) on the recognition by polyclonal antibodies from children living in Igbo-Ora, Nigeria. This would provide us with information on the possibility of eliciting mainly processing inhibitory antibodies with a recombinant MSP-1(19) vaccine. Blood was collected from children in the rainy season and binding of anti-MSP-1(19) antibodies to modified mutants of MSP-1(19) was analysed by ELISA. The MSP-1(19) mutant proteins with single substitutions at positions 22 (Leu-->Arg), 43 (Glu-->Leu) and 53 (Asn-->Arg) and the MSP-1(19) mutant protein with multiple substitutions at positions 27+31+34+43 (Glu-->Tyr, Leu-->Arg, Tyr-->Ser, Glu-->Leu); which had inhibitory epitopes; had the highest recognition. Children recognised both sets of mutants with different age groups having different recognition levels. The percentage of malaria positive individuals (32-80%) with antibodies that bound to the mutants MSP-1(19) containing epitopes that recognise only processing inhibitory and not blocking antibodies, were significantly different from those with antibodies that did not bind to these mutants (21-28%). The amino acid substitutions that abolished the binding of blocking antibodies without affecting the binding of inhibitory antibodies are of particular interest in the design of MSP-1(19) based malaria vaccines. Although these MSP-1(19) mutants have not been found in natural population, their recognition by polyclonal antibodies from humans naturally infected with malaria is very promising for the future use of MSP-1(19) mutants in the design of a malaria vaccine.

Variation in the relationship between anti-MSP-1(19) antibody response and age in children infected with Plasmodium falciparum during the dry and rainy seasons.

Malaria remains a major parasitic disease in Africa, with 300-500 million new infections each year. There is therefore an urgent need for the development of new effective measures, including vaccines. Plasmodium falciparum merozoite surface protein-1(19) (MSP-1(19)) is a prime candidate for a blood-stage malaria vaccine. Blood samples were collected from children aged 10 days to 15 years in the months of January-March (N = 351) and October-November (N = 369) corresponding to the dry and rainy seasons, respectively. P. falciparum infection was determined by microscopy and enzyme linked immunosorbent assay (ELISA) was used to determine the total IgG and IgG subclasses. There was a significant increase in the mean anti-MSP-1(19) antibody titre in the dry season (p < 0.05), compared to the rainy season. A significantly positive correlation between the anti-MSP-1(19) antibody titre and parasite density (p < 0.01, r = 0.138) was observed. In the rainy season, unlike in the dry season, P. falciparum positive children had higher anti-MSP-1(19) antibody titres than P. falciparum negative children and this difference was significant (p < 0.05). When all individuals were grouped together, the anti-MSP-1(19) antibody titre increased with age in both seasons (r = 0.186 and 0.002), this increase was more apparent in the dry season. However, when the study population was divided into P. falciparum positive and negative groups, it was observed that in the rainy season, there was a negative correlation between anti-MSP-1(19) titre and age in P. falciparum positive individuals, while those who were P. falciparum negative had a positive correlation between anti-MSP-1(19) titre and age. Analysis of anti-MSP-1(19) IgG subclass showed that IgG1 and IgG3 mean titres were highest in both the dry and rainy seasons with an increase in the mean antibody titres for IgG1, IgG2 and IgG3 in the rainy season. In the dry season there was a positive correlation between IgG1, IgG2, and IgG3 titres with age, while IgG4 was negative, whereas in the rainy season there was a positive correlation between IgG2 and IgG4 (non-cytophilic antibodies) with age and a negative correlation for IgG1 and IgG3 (cytophilic antibodies) with age. Seasonal differences in the level of MSP-1(19) IgG subclass titres were observed for P. falciparum negative and positive individuals. Only samples, which were positive for IgG2 and IgG4, showed positive correlation between parasitemia and total IgG. The incidence of P. falciparum infection, which increases during the rainy season, might be an important determinant of anti-MSP-1(19) antibody levels in children living in Igbo-Ora and the results point to the fact that non-cytophilic antibodies to MSP-1(19) in children might be associated with an increase in total IgG and parasitemia.

Effect of self-medication with antimalarial drugs on malaria infection in pregnant women in South-Western Nigeria.

OBJECTIVE: To determine the effect of self-medication with chloroquine and pyrimethamine on malaria infection and anaemia during pregnancy. SUBJECTS AND METHODS: The study involved 210 women who attended Ade Oyo Maternity State Hospital, Ibadan, Nigeria. Of these, 156 were pregnant women while 54 were not pregnant (controls). Of the pregnant women, 66 were primigravidae, while 90 were multigravidae. History of treatment of malaria with antimalarial drugs was obtained from the subjects. Gravidity and gestation period were also documented. Two millilitres of blood was withdrawn from each subject, for haematological parameters. Thin and thick films were prepared for malaria parasite identification and quantification. RESULTS: Of the primigravidae and multigravidae 68 and 16.4%, respectively, had taken antimalarial drugs prior to booking. Among primigravidae, only 18% of those with drugs compared with 32% without drugs were malaria-positive. The parasite density was significantly lower among those who took antimalarial drugs than among those who did not (976 +/- 60 versus 2,421 +/- 78, p < 0.05). Similarly, among multigravidae, only 16.4% of those who took antimalarial drugs compared with 34% of those who were not malaria-positive. The parasite density was also significantly lower in multigravidae with drugs than among those without drugs (350 +/- 45 versus 1,000 +/- 65, p < 0.05). The prevalence of anaemia (packed cell volume, PCV < 33) was high, 89% in primigravidae and 70% in multigravidae. Severe anaemia (PCV < 21) was more common in malaria-positive primigravidae and multigravidae than in malaria-negative women. CONCLUSION: The findings indicate that self-medication with chloroquine and pyrimethamine at booking was able to reduce the prevalence of malaria and anaemia in pregnancy.

Preliminary studies on the prevalence and distribution of urinary schistosomiasis in Ondo State, Nigeria.

The prevalence of S. haematobium infection in 18 Local Government Area (LGA) in Ondo state was determined by examining pupils from randomly selected schools in the state. A total of 4266 urine samples were examined and 1303 (30.5%) were infected with the parasite. The infection was recorded in both rural and urban communities in each LGA. The overall prevalence was significantly higher in males (33.7%) than in females (26.0%) (P = -0.001). The LGA exhibiting the highest overall prevalence of infection was Akure north (86.2%; Cl, 0.82-0.9). The infection was most common in subjects between the ages of 11 and 15 years. Seven species of aquatic snails were encountered and B. (P). globosus was the most abundant and widespread species. The Owena river/dam in Idanre LGA was richest in molluscan fauna. B. (P). globosus and Biomphalaria pfeifferi shedding cercariae were recovered from Owena river and dam. The study shows that there were spatial heterogeneities in the prevalence of infections in both human population and the snail intermediate hosts. The implications of the clustering nature of the disease, for a successful control program in the state, were discussed.

Urinary schistosomiasis among schoolchildren in Ibadan, an urban community in south-western Nigeria.

The current status of urinary schistosomiasis was assessed in Ibadan, an urban community in south-western Nigeria. Of 1331 children examined for eggs of S. haematobium in their urine, 17.4% were infected. Prevalence in postprimary schoolchildren was significantly (P < 0.01) higher (22.4%) than in primary schoolchildren (12.0%). Intensity of infection based on geometric mean egg count per 10 ml of urine was also higher in postprimary (36.7 eggs/10 ml urine) than primary pupils (29.9 eggs/10 ml urine). Boys had a significantly (P < 0.01) higher infection rate (24.1%) than girls (8.5%), and the intensity of infection was also higher (P < 0.01) in males (39.0 eggs/10 ml urine) than in females (22.1 eggs/10 ml urine). The overall geometric mean intensity of infection was highest (38.8 eggs/10 ml urine) in the 11-15 years age group. 42% of infected children excreted > 50 eggs/10 ml urine. 2.2% excreted S. mansoni eggs in urine. Water contact activities were more frequent (P < 0. 01) in males (31.8%) than females (38.2%). Nine species of snails were encountered, with B. (p) globosus being the the most abundant and widespread. These results show that urinary schistosomiasis is still being actively being transmitted in Ibadan.

Antagonistic effects of Schistosoma mansoni on superimposed Hymenolepis diminuta and H. microstoma infections in mice.

Patent, but not prepatent, Schistosoma mansoni infections in mice enhanced the expulsion of a superimposed infection with Hymenolepis diminuta. An antagonistic effect was also directed against a superimposed H. microstoma infection in mice harbouring patent S. mansoni infections.

Concurrent infections of the trematode Echinostoma caproni and the tapeworms Hymenolepis diminuta and Hymenolepis microstoma in mice.

Superimposing the intestinal tapeworm Hymenolepis diminuta on an established infection with the trematode Echinostoma caproni or simultaneous infection of mice with H. diminuta and Hymenolepis microstoma caused destrobilation and expulsion of H. diminuta, whereas establishment and growth of H. microstoma under the same infection regimes were not affected. In contrast, simultaneous superimposition of H. diminuta and H. microstoma on an established E. caproni infection caused destrobilation and expulsion of both H. diminuta and H. microstoma.

Echinostoma population regulation in experimental rodent definitive hosts.

Echinostoma population regulation in the experimental rodent host is governed by the capacity of the latter to express an effective regulatory response. Parasite establishment, survival and fecundity are affected by host-related factors such as species, strain and age and by parasite-related factors such as species, age and the burden of infection. The genetic heterogeneity in the regulatory response to infection is marked. The most intensively studied host/echinostome combinations comprise E. caproni and E. trivolvis in the mouse host, for which a range of interesting host-parasite relationships has been demonstrated, including concomitant immunity with rapid expulsion of superimposed infections, a long-lasting resistance to secondary infection, a negatively dose-dependent pattern of expulsion of primary infections, a positively dose-dependent reproductive potential, an infective-dose independency of primary worm establishment, and a range of heterologous antagonistic and synergistic interactions in concurrent infections with related and unrelated parasite species. The Echinostoma/rodent model is highly suitable for studying aspects of parasite population regulation in intestinal trematode infections.

Heterologous synergistic interactions in concurrent experimental infection in the mouse with Schistosoma mansoni, Echinostoma revolutum, Plasmodium yoelii, Babesia microti, and Trypanosoma brucei.

Primary infections with Plasmodium yoelii and Echinostoma revolutum in the mouse induced a significant increase in the heterologous Schistosoma mansoni challenge worm establishment, whereas S. mansoni worm establishment remained unaffected by primary infections with Trypanosoma brucei and Babesia microti. Concurrent infection in the mouse with P. yoelii or T. brucei, but not with B. microti, blocked the resistance to homologous E. revolutum challenge infection, and primary P. yoelii and T. brucei infections and corticosteroid treatment made naive, innately resistant mice susceptible to E. revolutum infection. Innate resistance to infection with E. revolutum, the pattern of expulsion of low-level E. revolutum infections, and resistance to homologous S. mansoni challenge infection remained unaffected by concurrent B. microti infection. Primary, heavy E. revolutum infections in the mouse resulted in the enhancement of subsequent infection with B. microti, whereas primary infection with S. mansoni suppressed subsequent B. microti infection in some but not all experiments. In a single experiment, P. yoelii infection was suppressed markedly by primary S. mansoni infection, whereas the enhancement of P. yoelii infection in concurrently E. revolutum-infected mice was seen in only one of the several experiments conducted. However, no interference with resistance to homologous B. microti and P. yoelii challenge infection was induced by concurrent infection with S. mansoni and E. revolutum. We suggest that the synergistic interactions demonstrated between protozoans and helminths in concurrent experimental infection in the mouse are induced by immunosuppression.