Objectives: To investigate the prevalence and intensity of intestinal helminth infections in pregnant Cameroonian women and assess their anaemic status. Design: Longitudinal study. Setting: Buea Integrated Health Centre, Muea Health Centre, Mutengene Integrated Health Centre and the University of Buea Life Sciences Laboratory. Subjects: Two hundred and six pregnant women. Interventions: Stool and blood samples were collected from 206 pregnant women during three consecutive visits of each participant to the clinic, and used for identification and quantification of eggs of soil-transmitted nematodes and determination of packed cell volume respectively. The pregnant women received mebendazole and iron tablets on the day of enrollment at the antenatal clinic to control helminth infections and anaemia. Main outcome measures: The impact of antenatal clinical visits on the prevalence of helminth infections and the anaemic status of the women during pregnancy were assessed. Results: The results revealed that infection rate of intestinal nematodes was 47.10/0 during the first antenatal visit. This dropped to 27.2% during the second visit and 8.70/0 during the third visit. The prevalence was significantly higher in primigravidae than multigravidae during the first (P<0.001) and second (P<0.03) antenatal visits. More single women than married women were found infected with intestinal nematodes during the three visits, the difference being significant only during the first visit (P<0.01). Most of the infected women were those who attended clinic at Muea, a semiurban community. At the first antenatal visit, multigravidae had a heavier load of all three nematode species than primigravidae while single women carried a heavier burden of A. lumbricoides and T. trichiura than married women. At the second visit, primigravidae and single women carried a heavier burden of Ascaris and hookworm than multigravidae and married women respectively. Overall, the intensity of helminth infection increased after the first visit while prevalence dropped, but both had dropped by the third visit. The Ascaris/Trichuris combination was the most prevalent in mixed species infections, while A. lumbricoides was the most prevalent in single species infection. The prevalence of anaemia (PCV<31%) was 53.4% on the first antenatal visit, 50.0% on the second and 28.2% on the third antenatal visit. Significantly more primigravidae than multigravidae were anaemic on the first and second visits (P<0.003 and P<0.001 respectively). More anaemic cases were recorded among women attending clinic in Mutengene than in Muea and Buea (P<0.05). Conclusion: Prevalence of soil-transmitted helminth infections in pregnant Cameroonian women was 47.1 %, with single and mixed species infections present at 28.6% and 18.5% respectively. Primigravidae and single women were more vulnerable to helminth infections than multigravidae and married women. The results provide evidence in support of anthelmintic treatment in prenatal programmes.

In the many areas where human malaria and helminthiases are co-endemic, schoolchildren often harbour the heaviest infections and suffer much of the associated morbidity, especially when co-infected. In one such area, the Buea district, in south-western Cameroon, two cross-sectional surveys, together covering 263 apparently healthy schoolchildren aged 4-12 years, were recently conducted. The prevalences of fever, malarial parasitaemia and intestinal helminth infections, the seroprevalences of anti-Plasmodium falciparum IgG and IgE and anti-glycosylphosphatidylinositol (anti-GPI) IgG, plasma concentrations of total IgE, and the incidence of anaemia were all investigated.The mean (S.D.) age of the study children was 7.56 (1.82) years. Overall, 156 (59.3%) of the children were found parasitaemic, with a geometric mean parasitaemia of 565 parasites/mu l. Parasitaemia and fever were significantly associated (P=0.042). The children who lived at low altitude, attending schools that lay 400-650 m above sea level, had significantly higher parasitaemias than their high-altitude counterparts (P < 0.01). At low altitude, the children attending government schools had significantly higher parasitaemias than their mission-school counterparts (P=0.010). Of the 31 children (11.9%) found anaemic, 22 (70.4%) had mild anaemia and none had severe anaemia. A significant negative correlation (r=-0.224; P=0.005) was observed between haemoglobin concentration and level of parasitaemia. Infection with Plasmodium appeared to reduce erythrocyte counts (P=0.045), a condition that was exacerbated by co-infection with helminths (P=0.035). Plasma concentrations of total IgE were higher in the children found to be excreting helminth eggs than in those who appeared helminth-free, while levels of anti-P. falciparum IgE were higher in the children with low-grade parasitaemias than in those with more intense parasitaemias. Levels of anti-GPI IgG increased with age and were relatively high in the children who lived at low altitude and in those who were aparasitaemic.The survey results confirm that asymptomatic malarial parasitaemia frequently co-exists with helminth infections in schoolchildren and indicate links with fever, altitude and school type. Immunoglobulin E may play a role in immune protection against helminthiasis whereas anti-GPI antibodies may be important in the development of antimalarial immunity in such children. In Cameroon, as in other areas with endemic malaria, control programmes to reduce the prevalences of infections with intestinal helminths and malarial parasites in schoolchildren, which may effectively reduce the incidence of anaemia, are clearly needed.

Objectives: To investigate the effects of age, gravidity, and gestational age on peripheral malaria parasitemia and functional T helper (Th) cell heterogeneity in pregnant women. Methods: Maternal age, gravidity, and gestational age were recorded and peripheral venous blood collected from 175 women attending antenatal clinics in south western Cameroon between March and September 2002. The blood was checked for malaria parasiternia by light microscopy and plasma levels of interteukin (IL)-4 and human interferon (IFN)-gamma were measured by indirect enzyme-linked immunosorbent assay. Results: Malaria parasites were detected in 45 (25.4%) of 174 women, with rates similar for different age groups, trimesters of pregnancy, and gravidity. The geometric mean parasite density was 565, and parasite density was significantly higher in younger than in older women. For all groups combined, the mean IL-4 level was significantly higher than the mean IFN-gamma (P=0.0004), irrespective of the presence and density of malaria parasites, gravidity except for women in their first trimester of pregnancy and grandmultiparas, who had similar levels of IFN-gamma and IL-4. In general, the cytokine profile was biased toward Th2-type of responses in 112 (84.3%) of 132 women. Conclusions: In this study the ability to control malaria parasitemia during pregnancy was found to be predominantly age dependent, suggesting naturally acquired immunity. Furthermore, the systemic cytokine profile was found to be biased towards Th2 responses, a prerequisite for a successful pregnancy. This pattern was unaffected by maternal age, gestational age, gravidity, or parasitemia. (c) 2007 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

Objectives: In this study, the effect of maternal peripheral and placental Plasmodium falciparum parasitaemia on the level of antibody and cytokine immune responses in the neonate was investigated.Methods: Malaria parasites were detected by light microscopy. Levels of malaria-specific isotypic antibodies were measured in maternal and cord blood by indirect ELISA. The numbers of IFN-gamma and IL-4 cells produced by maternal/cord blood after in vitro stimulation were enumerated using the ELISPOT assay.Results: Malaria parasite rate of maternal, placental biopsy and cord blood was 32.8%, 33.7% and 7.8% respectively. Overall, ELISA seropositivity rates for P. falciparum-specific IgG, IgM, IgE and IgA in the maternal plasma samples were 71%, 85%, 29.3%, and 0% respectively, while those for the cord samples were 69%, 6.0%, 4.4% and 0% respectively. Mean IgM ELISA OD405 values of neonates born from positive placentas, or whose mothers had peripheral malaria parasitaemia were higher than those who were parasite negative. The mean number of maternal cells producing IFN-gamma was higher (P = 0.0001) than that of the paired cord samples. The mean number of IL-4 producing cells of neonates born of mothers who were positive (P < 0.05) or from malaria-positive placentas (P < 0.025) was higher than from those who were malaria negative. Neonates born of malaria-positive mothers or from parasitized placentas mounted predominantly Th2 type immune responses.Conclusion: It appears from this study that neonates born from malaria-infected mothers or placentas may relatively be more susceptible to malaria attack during the first years of life. (c) 2005 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Anaemia in pregnancy has been associated with maternal morbidity and mortality and is a risk factor for low birthweight. The importance of malaria as a major cause of anaemia in pregnancy in malaria endemic areas has not been fully elucidated. In two cross-sectional studies of pregnant women at antenatal enrolment and at delivery, we determined the prevalence of anaemia and assessed some risk factors associated with anaemia such as malaria parasitaemia and parity, in women from a malaria endemic area of south western Cameroon. Of the 1118 women whose Hb levels were analysed at first antenatal enrolment, 68.9% were anaemic (Hb<11.0 g/dL) although only 1.3% were severely anaemic (Hb<7 g/dl). At delivery, 69.9% (485/694) of the parturient women were anaemic with 4.3% having severe anaemia. The mean haemoglobin (Hb) level of the pregnant women at enrolment and at delivery was not significantly different. The mean Hb level of malaria parasite positive pregnant women (P=0.0001) and parturient women (P=0.0001) were significantly lower than those who were malaria parasite free. Similarly, the mean Hb level of primigravidae at antenatal enrolment (P=0.0001) and at delivery (primiparae; P=0.0001) was markedly lower than that of multigravidae or multiparae, respectively. Of the anaemic cases, 52.1% were malaria positive while 47.9% were malaria free at enrolment. By contrast, 36.9% (179/485) of the anaemic cases were associated with maternal malaria parasitaemia while 37.3% (174/466) were associated with placental malaria parasitisation. Thus at delivery, anaemia was more common in women without malaria parasitaemia (P=0.0003) or whose placentas were malaria free (63.1% vs 36.9%; P<0.05). The prevalence of anaemia was significantly higher (OR=2.399; P=0.001) in mothers whose peripheral blood and placental biopsy were free of malaria parasites (69.9%) than in those whose peripheral and placental samples had malaria parasites. The mean birthweight and placental weights of newborns of mothers with and without anaemia were similar. In addition, there was no association between maternal anaemia and the incidence of low birthweight. Our study demonstrates a high prevalence of mild to moderate anaemia amongst the study population with relatively low incidences of severe anaemia. Furthermore, at delivery >50% of the anaemic cases were not associated with maternal or placental malaria parasitaemia suggesting the existence of other causes of anaemia in this community. This observation is important in developing a strategy for controlling anaemia in the community.

OBJECTIVE:To evaluate clinical, parasitological and haematological responses to quinine sulphate therapy in patients with uncomplicated malaria using the 14-day WHO protocol.DESIGN:Longitudinal study.SETTING:The Buea Provincial hospital annex located in South Western Cameroon.SUBJECTS:The study participants consisted of children (> or = 8 months) and adults (< or = 550 years) with acute malaria attending the outpatient division of health institutions within Fako Division.RESULTS:Quinine sulphate failure was found in 42% of the patients. Of these 10% were resistant at the RI while 32% were at the RII level. Clinically, the overall success rate (ACR) was 94.2% while therapeutic failures (ETF and LTF) were observed in four patients (5.8%). 27.4% and 17.4% of the patients were anaemic at enrolment and day 14 respectively. The mean PCV levels of the patients increased during the follow-up period except on day three when mean PCV levels dropped. The difference in the mean PCV levels during the follow-up was significant (F = 60.29; P = 0.0001).CONCLUSION:The relatively high resistance of quinine sulphate observed in this study suggests the need to monitor the spread of resistance to this drug in the study region.

Plasmodium falciparum-infected erythrocytes have been reported to sequester in the placenta by adhering to chondroitin 4-sulfate during pregnancy. Earlier studies have highlighted higher susceptibility of primigravidae to P. falciparum compared to multigravidae living within the same endemic areas. The haptoglobin phenotype (Hp1-1) has been associated with susceptibility to severe P. falciparum malaria and the presence of Hp in human endometrium has been reported. The possible role of different Hp phenotypes in susceptibility to or protection from placental infection by P. falciparum in both primigravid and multigravid women at delivery in western Cameroon was investigated in this study. Only the three major haptoglobin phenotypes; Hp1-1, Hp2-1 and Hp2-2, were found in the study population with the Hp1-1 phenotype being the predominant (53%). There was no significant difference in the distribution of the three Hp phenotypes between the two gravidity groups. Women carrying the Hp1-1 phenotype had higher parasite prevalences in both peripheral blood (21.6% against 9.1%) and placentas (42% against 16.7%) when compared to those with the Hp2-2 phenotype. The difference in the parasite density between women carrying the Hp1-1 and Hp2-2 phenotypes was statistically significant for placental infection (P=0.001) but not for maternal peripheral blood infection. Placental parasitaemias without peripheral blood parasitaemias were detected in 42.6% of all the P. falciparum positive women while 27.7% of the women had peripheral blood parasitaemias in the absence of placental infection and 29.8% of the women had both placental and peripheral blood parasitaemias. A statistically significant difference was observed between the primigravidae and multigravidae in the parasite density in placental biopsies (P=0.02) but not for maternal peripheral blood parasitaemia. Our data suggest that the Hp1-1 phenotype may play a role in susceptibility to placental infection by P. falciparum during pregnancy.

OBJECTIVES:To investigate the prevalence of asymptomatic malaria parasitaemia and anemia in nursery and primary school children and correlate parasite density with haemoglobin levels.DESIGN:Cross sectional study.SETTING:Samples were collected from children attending the Saint Theresa's bilingual school and the Government Primary school, Buea, South West Province, Cameroon.SUBJECTS:297 nursery and primary school children two to 11 years old selected based on parental consent. MAIN OUTOME MEASURES: Relationship between asymptomatic malaria and anaemia.RESULTS:The prevalence of asymptomatic malaria in children was 30.3%. Parasite prevalence and density was independent of age and sex (p > 0.05). The mean haemoglobin level for parasitaemic children was 11.9 g/dl (+/- SD1.1) compared with 12.1 g/dl (+/- 1.2) for non-parasitaemic children. The difference was not significant (t = 1.918, p > 0.05). Anaemia when present was mild. No correlation was found between malaria parasite density and haemoglobin levels (r = -0.065; p > 0.05).CONCLUSION:Asymptomatic malaria was accompanied by low grade parasitaemia, which did not seem to have a significant effect on haemoglobin levels.

Blood samples were collected from one hundred and sixteen parturient women and one hundred and seventeen umbilical cords at delivery for the detection of malaria parasitaemia and determination of total serum immunoglobulins (IgG, IgM and IgA). Immunoglobulin levels were measured by the single radial immunodiffusion method and the enzyme-linked immunosorbent assay for cord blood IgM. Malaria parasites were found in 2.6% (3/117) of cord blood and 22.4% (26/116) of maternal samples. Primiparae had the highest incidence and density of parasites compared with multiparae. A negative correlation was obtained between parasite density and parity of the parturient women (r = -0.54, P < 0.005). Mean cord blood IgG (P < 0.001) and IgM (P < 0.0001) were significantly lower than the mean maternal IgG and IgM. Maternal IgG (r = 0.65, P < 0.001) but not IgM (r = 0.09, P < 0.50) correlated with those of cord blood. Mean IgM (P < 0.001) but not IgG (P > 0.50) and IgA (P < 0.40) was significantly higher in malaria positive parturient women compared with malaria negative women. These data confirms the transplacental transfer of IgG across the placenta and the higher incidence of malaria parasitaemia in primiparae. The presence of IgM in cord blood samples suggest intrauterine sensitization of the foetus to common infections.

Bimonthly surveys were carried out for 12 months to investigate the dynamics of the acquisition of malaria parasitemia in relation to hemoglobin genotype, development of anemia, and body weight in infants during their first year of life. Thick blood smears for malaria, a capillary blood sample for measurement of packed cell volume (PCV) levels, and body weights were obtained at each survey. Generally, parasite rates (P < 0.001) and mean parasite densities (P < 0.025) increased with age. With a few exceptions, parasite rates and densities were similar in infants with hemoglobin AA and AS during the first year of life. Malaria parasitemia significantly lowered the PCV levels of the study infants only at four (P < 0.001), six (P < 0.025), eight (P < 0.001), and 10 (P < 0.01) months of age. No significant difference was observed in the mean body weight of malaria-positive and -negative infants during the first year of life except in infants two months of age (P < 0.05). The fairly rapid increase in parasite rate and density after two months of age is indicative of the decrease in protection after the first 2-3 months of life.

A cohort of 117 newborns was followed longitudinally for 12 months to determine the age of onset of clinical malaria and the subsequent episodes of malaria, and to investigate the possible existence of a correlation between level of transplacentally acquired Plasmodium falciparum-specific antibodies and age of onset of malaria in the infant. The mean age of onset of malaria in 49 infants was 4.48 +/- 1.54 months. Mean (+/- S.D.) age of onset of clinical malaria in haemoglobin AA infants (4.38 +/- 1.14) was significantly (P < 0.05) lower compared with haemoglobin AS (5.58 +/- 2.43) infants. No correlation was obtained between the age of onset of malaria and the level of cord serum total IgG, IgM and antibodies to P. falciparum antigens. Cord blood seropositivity for antibodies to the blood stage antigen Pf155/RESA and its C-terminal repeat sequence (EENV)6 or to the (NANP)6 peptide representing repeats of the circumsporozoite protein (CSP) did not influence the age of onset of clinical malaria. However, infants with haemoglobin AS whose cord blood was seropositive for antibodies to the (EENV)6 or (NANP)6 peptide showed delayed onset (P < 0.001) of malaria compared with AA seropositive infants. Although our results indicate that transplacentally acquired antibodies to the studied antigens alone offer no significant protection against malaria during the first few months of life, antibodies in concert with other factors such as haemoglobin genotype may contribute to the protection of the newborn.

Malaria parasite rates, parasite densities and seroreactivities to two Plasmodium falciparum antigens (Pf155/RESA and circumsporozoite protein) were investigated in a random sample of 416 blood donors attending the Blood Transfusion Unit of the University College Hospital in Ibadan, south-western Nigeria: 224 in October-November 1991 and 192 in March 1992. The incidence of malaria parasitaeia observed in 1991 was significantly higher than that seen in 1992 (41% v. 19%; P < 0.001). In contrast, the geometric mean parasite density in 1992 was significantly higher than in 1991 (440 v. 191) parasites/microliters blood; P < 0.001). Although parasite rates were highest in the group aged 25-31 years in both surveys, there was no apparent correlation between age of donor and parasite density in either survey. Parasite density was significantly higher in AA- than in AS-haemoglobin individuals only in the 1992 survey (P = 0.050). All the blood donors were seropositive for antibodies to crude parasite antigens, indicating heavy exposure to malaria infection. Seroreactivity to Pf155/RESA was similar in the two surveys but that to circumsporozoite protein (CSP) was significantly higher in 1991 than in 1992 (P < 0.001). The seropositivity rates were generally similar to malaria-positive and -negative blood donors. In 1992, however, all the blood donors with high reactivities to Pf155/RESA, as detected by erythrocyte membrane immunofluorscence, were negative for malaria parasites, indicating that this group was relatively protected against malaria parasitaemia. It is recommended that blood samples from prospective blood donors be examined for malaria parasites and that recipients of malaria-infected blood samples be given a curative regimen of antimalarials.

The kinetics of passively transferred maternal antibodies to antigens of Plasmodium falciparum and the dynamics of acquisition of these antibodies during the first year of life was investigated in infants born in a malaria endemic area of south-western Nigeria. Blood samples were collected from the infants at bi-monthly follow-up visits for the analysis of total serum immunoglobulin G, IgM, IgA and antibodies to the antigen Pf155/RESA and against synthetic peptides representing antigenic sequences of the blood stage antigen Pf155/RESA and Ag332 or the circumsporozoite protein (CSP). IgG levels fell from birth till 4 months and a steady rise was observed thereafter till ten months of life. On the contrary mean IgM and IgA levels increased throughout the first year of life. Generally the number of infants positive for antibodies to the antigens under investigation fell from birth and between 4-6 months of age was either low or absent. None of the infants were positive for antibodies to the peptide representing Ag332 during the first year of life. The earliest seroconversion was detected at 6 months of age involving the Pf155/RESA and (NANP)6 antigens. The results indicate a high level of exposure in this study area to malaria infection early in life. The finding of an active antibody response to malarial antigens in infancy encourages the hope that a malaria vaccine administered early in life may accelerate the development of naturally acquired immunity and thus protect the population most at risk.

Paired maternal-cord serum samples were analysed for antibodies to the Pf155/RESA and circumsporozoite protein (CSP) antigens of Plasmodium falciparum. Malaria parasites were found in 2.6% (3/117) of cord blood and 22.4% (26/116) of maternal samples. Immunofluorescence assays detected P. falciparum-specific IgG antibodies in all paired samples while P. falciparum-specific IgM was detected in 5.8% (7/121) of cord samples. The positivity rates for antibodies to Pf155/RESA and (NANP)6 but not (EENV)6, a C-terminal repeat sequence of Pf155/RESA, were significantly higher in maternal as compared with cord samples. Seropositivity rates to Pf155/RESA and (EENV)6 were not related to maternal parity group while positivity rates to the (NANP)6 peptide were higher in primiparae and multiparae of > or = 4 parity. These data confirm the transplacental transfer of P. falciparum-specific antibodies and the higher incidence of malaria parasitaemia in primiparae. The presence of P. falciparum-specific IgM in some cord samples suggests intrauterine sensitization of the foetus to malarial antigens.