Failure of chloroquine prophylaxis for falciparum malaria in pregnant women in Madang, Papua New Guinea

Prevalence of malaria in HIV positive and HIV negative pregnant women attending antenatal clinics in south eastern Nigeria

INTRODUCTION

Globally, malaria in pregnancy is a public health challenge. Malaria and HIV are among the two most important diseases contributing to the global health burden of our time. HIV positive pregnant women are at increased risk of all the adverse outcomes of malaria in pregnancy.

OBJECTIVE

The objective of this study was to compare malaria parasitaemia between HIV positive and HIV negative pregnant women attending antenatal clinics offering Preventing Maternal to Child Transmission (PMTCT) services in Enugu metropolis, south-eastern Nigeria.

METHODS

A descriptive cross sectional study was conducted among 200 HIV positive and 200 HIV negative pregnant women attending antenatal clinics in Enugu. Two out of five hospitals that provide PMTCT services were selected through balloting. Finger pricked blood samples were collected and thick blood films were examined for malaria parasite using giemsa expert microscopy. A structured interviewer administered questionnaire was used for data collection. Data was analysed using SPSS version 22.

RESULTS

The HIV positive pregnant women (152) (76%) and HIV negative women (137) (68.5%) studied were mostly in the age range of 25-34 years. Mean gestational age of HIV positive and HIV negative participants were 23.4±10.7 and 23.2±10.1 weeks respectively (P=0.001). The prevalence of malaria infection among HIV positive pregnant mothers was 81% (162/200) and 75% (150/200) among HIV negative pregnant women (P < 0.001). The HIV positive mothers had more moderate parasitaemia (86/200: 53.1%) compared to 43/200: 28.7% in HIV negative mothers (P<0.001). Even though more HIV positive mothers (54.5%) used insecticide treated nets ITNs during pregnancy compared to 41.5% in HIV negative mothers, moderate malaria parasitaemia was higher in HIV positive mothers. HIV positive nulliparous pregnant women had the highest rate of malaria parasitaemia (32/36: 88.9%).

CONCLUSION

Moderate malaria parasitaemia was higher among HIV positive pregnant women. All malaria preventive strategies should be intensified in pregnancy as ITNs provided little protection.

Risk factors and pregnancy outcomes associated with placental malaria in a prospective cohort of Papua New Guinean women

Background

Plasmodium falciparum in pregnancy results in substantial poor health outcomes for both mother and child, particularly in young, primigravid mothers who are at greatest risk of placental malaria (PM) infection. Complications of PM include maternal anaemia, low birth weight and preterm delivery, which contribute to maternal and infant morbidity and mortality in coastal Papua New Guinea (PNG).

Methods

Placental biopsies were examined from 1451 pregnant women who were enrolled in a malaria prevention study at 14–26 weeks gestation. Clinical and demographic information were collected at first antenatal clinic visits and women were followed until delivery. Placental biopsies were collected and examined for PM using histology. The presence of infected erythrocytes and/or the malaria pigment in monocytes or fibrin was used to determine the type of placental infection.

Results

Of 1451 placentas examined, PM infection was detected in 269 (18.5%), of which 54 (3.7%) were acute, 55 (3.8%) chronic, and 160 (11.0%) were past infections. Risk factors for PM included residing in rural areas (adjusted odds ratio (AOR) 3.65, 95% CI 1.76–7.51; p ≤ 0.001), being primigravid (AOR 2.45, 95% CI 1.26–4.77; p = 0.008) and having symptomatic malaria during pregnancy (AOR 2.05, 95% CI 1.16–3.62; p = 0.013). After adjustment for covariates, compared to uninfected women, acute infections (AOR 1.97, 95% CI 0.98–3.95; p = 0.056) were associated with low birth weight babies, whereas chronic infections were associated with preterm delivery (AOR 3.92, 95% CI 1.64–9.38; p = 0.002) and anaemia (AOR 2.22, 95% CI 1.02–4.84; p = 0.045).

Conclusions

Among pregnant PNG women receiving at least one dose of intermittent preventive treatment in pregnancy and using insecticide-treated bed nets, active PM infections were associated with adverse outcomes. Improved malaria prevention is required to optimize pregnancy outcomes.

Malaria and immunity during pregnancy and postpartum: a tale of two species

It is well established that pregnant women are at an increased risk of Plasmodium falciparum infection when compared to non-pregnant individuals and limited epidemiological data suggest Plasmodium vivax risk also increases with pregnancy. The risk of P. falciparum declines with successive pregnancies due to the acquisition of immunity to pregnancy-specific P. falciparum variants. However, despite similar declines in P. vivax risk with successive pregnancies, there is a paucity of evidence P. vivax-specific immunity. Cross-species immunity, as well as immunological and physiological changes that occur during pregnancy may influence the susceptibility to both P. vivax and P. falciparum. The period following delivery, the postpartum period, is relatively understudied and available epidemiological data suggests that it may also be a period of increased risk of infection to Plasmodium spp. Here we review the literature and directly compare and contrast the epidemiology, clinical pathogenesis and immunological features of P. vivax and P. falciparum in pregnancy, with a particular focus on studies performed in areas co-endemic for both species. Furthermore, we review the intriguing epidemiology literature of both P. falciparum and P. vivax postpartum and relate observations to the growing literature pertaining to malaria immunology in the postpartum period.

Knowledge, attitudes, and practices concerning malaria in pregnancy: results from a qualitative study in Madang, Papua New Guinea

Background

Malaria is the leading cause of illness and death in Papua New Guinea (PNG). Infection during pregnancy with falciparum or vivax malaria, as occurs in PNG, has health implications for mother and child, causing complications such as maternal anemia, low birth weight and miscarriage. This article explores knowledge, attitudes and practices concerning malaria during pregnancy and it’s prevention in Madang, PNG, a high prevalence area.

Methods

As part of a qualitative study in Madang, exploring MiP, participatory techniques (free-listing and sorting) were conducted along with focus group discussions, in-depth interviews (with pregnant women, health staff and other community members) and observations in the local community and health facilities.

Results

The main themes explored were attitudes towards and knowledge of MiP, its risks, and prevention. Although there was a general awareness of the term “malaria”, it was often conflated with general sickness or with pregnancy-related symptoms. Moreover, many preventive methods for MiP were related to practices of general healthy living. Indeed, varied messages from health staff about the risks of MiP were observed. In addition to ideas about the seriousness and risk of MiP, other factors influenced the uptake of interventions: availability and perceived comfort of sleeping under insecticide-treated mosquito nets were important determinants of usage, and women’s heavy workload influenced Chloroquine adherence.

Conclusion

The non-specific symptoms of MiP and its resultant conflation with symptoms of pregnancy that are perceived as normal have implications for MiP prevention and control. However, in Madang, PNG, this was compounded by the inadequacy of health staff’s message about MiP.

Malaria prevention during pregnancy-is there a next step forward?

Richard Steketee discusses the two studies by Clara Menendez and colleagues that describe using mefloquine for the intermittent preventative therapy of malaria in both HIV positive and HIV negative pregnant women and outlines the next steps.

Please see later in the article for the Editors' Summary

Impact of community-based interventions for the prevention and control of malaria on intervention coverage and health outcomes for the prevention and control of malaria

In this paper, we aim to evaluate the effectiveness of community-based interventions (CBIs) for the prevention and management of malaria. We conducted a systematic review and identified 42 studies for inclusion. Twenty-five of the included studies evaluated the impact of the community-based distribution of insecticide-treated nets (ITNs), indoor residual spraying (IRS), or impregnated bed sheets; 14 studies evaluated intermittent preventive therapy (IPT) delivered in community settings; two studies focused on community-based education for malaria prevention; and one study evaluated environmental management through drain cleaning.

Our analysis suggests that, overall, the community-based delivery of interventions to prevent and control malaria resulted in a significant increase in ITNs ownership (RR: 2.16, 95% CI: 1.86, 2.52) and usage (RR: 1.77, 95% CI: 1.48, 2.11). However, usage of ITNs was limited to two-thirds of the population who owned them. Community-based strategies also led to a significant decrease in parasitemia (RR: 0.56, 95% CI: 0.42, 0.74), malaria prevalence (RR: 0.46, 95% CI: 0.29, 0.73), malaria incidence (RR: 0.70, 95% CI: 0.54, 0.90), and anemia prevalence (RR: 0.79, 95% CI: 0.64, 0.97). We found a non-significant impact on splenomegaly, birth outcomes (low birth weight, prematurity, stillbirth/miscarriage), anthropometric measures (stunting, wasting, and underweight), and mortality (all-cause and malaria-specific). The subgroup analysis suggested that community-based distribution of ITNs, impregnated bed sheets and IRS, and IPT are effective strategies. Qualitative synthesis suggests that high coverage could be achieved at a lower cost with the integration of CBIs with existing antenatal care and immunization campaigns. Community-based delivery of interventions to prevent and control malaria are effective strategies to improve coverage and access and reduce malaria burden, however, efforts should also be concerted to prevent over diagnosis and drug resistance.

Factors affecting attendance at and timing of formal antenatal care: results from a qualitative study in Madang, Papua New Guinea

BACKGROUND

Appropriate antenatal care (ANC) is key for the health of mother and child. However, in Papua New Guinea (PNG), only a third of women receive any ANC during pregnancy. Drawing on qualitative research, this paper explores the influences on ANC attendance and timing of first visit in the Madang region of Papua New Guinea.

METHODS

Data were collected in three sites utilizing several qualitative methods: free-listing and sorting of terms and definitions, focus group discussions, in-depth interviews, observation in health care facilities and case studies of pregnant women. Respondents included pregnant women, their relatives, biomedical and traditional health providers, opinion leaders and community members.

RESULTS

Although generally reported to be important, respondents' understanding of the procedures involved in ANC was limited. Factors influencing attendance fell into three main categories: accessibility, attitudes to ANC, and interpersonal issues. Although women saw accessibility (distance and cost) as a barrier, those who lived close to health facilities and could easily afford ANC also demonstrated poor attendance. Attitudes were shaped by previous experiences of ANC, such as waiting times, quality of care, and perceptions of preventative care and medical interventions during pregnancy. Interpersonal factors included relationships with healthcare providers, pregnancy disclosure, and family conflict. A desire to avoid repeat clinic visits, ideas about the strength of the fetus and parity were particularly relevant to the timing of first ANC visit.

CONCLUSIONS

This long-term in-depth study (the first of its kind in Madang, PNG) shows how socio-cultural and economic factors influence ANC attendance. These factors must be addressed to encourage timely ANC visits: interventions could focus on ANC delivery in health facilities, for example, by addressing healthcare staff's attitudes towards pregnant women.

The epidemiology of postpartum malaria: a systematic review

Pregnant women are more susceptible to malaria than their non-pregnant counterparts. Less is known about the risk of malaria in the postpartum period. The epidemiology of postpartum malaria was systematically reviewed. Eleven articles fitted the inclusion criteria. Of the 10 studies that compared malaria data from the postpartum period with pregnancy data, nine studies suggested that the risk for malaria infection decreased after delivery. All three studies that compared postpartum data with non-pregnant non-postpartum women concluded that the risk did not return to pre-pregnancy levels immediately after delivery. The results of this review have to be carefully interpreted, as the majority of studies were not designed to study postpartum malaria, and there was large variability in study designs and reported outcomes. Current evidence suggests an effort should be made to detect and radically cure malaria during pregnancy so that women do not enter the postpartum period with residual parasites.

Malaria in pregnancy in the Asia-Pacific region

Most pregnant women at risk of for infection with Plasmodium vivax live in the Asia-Pacific region. However, malaria in pregnancy is not recognised as a priority by many governments, policy makers, and donors in this region. Robust data for the true burden of malaria throughout pregnancy are scarce. Nevertheless, when women have little immunity, each infection is potentially fatal to the mother, fetus, or both. WHO recommendations for the control of malaria in pregnancy are largely based on the situation in Africa, but strategies in the Asia-Pacific region are complicated by heterogeneous transmission settings, coexistence of multidrug-resistant Plasmodium falciparum and Plasmodium vivax parasites, and different vectors. Most knowledge of the epidemiology, effect, treatment, and prevention of malaria in pregnancy in the Asia-Pacific region comes from India, Papua New Guinea, and Thailand. Improved estimates of the morbidity and mortality of malaria in pregnancy are urgently needed. When malaria in pregnancy cannot be prevented, accurate diagnosis and prompt treatment are needed to avert dangerous symptomatic disease and to reduce effects on fetuses.

Intermittent preventive treatment of malaria with sulphadoxine-pyrimethamine during pregnancy in Burkina Faso: effect of adding a third dose to the standard two-dose regimen on low birth weight, anaemia and pregnancy outcomes

Background

Intermittent preventive treatment with sulphadoxine-pyrimethamine (IPTp-SP) is being implemented in most malaria endemic countries as a standard two-doses regimen as it reduces the risk of low birth weight (LBW) and the prevalence of maternal anaemia. Nevertheless, where the risk of infection close to delivery is high because of intense transmission, a third IPTp-SP dose may further reduce the negative effects of malaria on pregnancy outcome.

Methods

Pregnant women in the 2^nd or 3^rd trimester were randomized to receive either 2 (SP2) or 3 doses (SP3) of SP. Trained field workers paid home visits to the women for drug administration according to a predefined drug delivery schedule. Women were encouraged to attend their scheduled ANC visits and to deliver at the health facilities where the new-born was weighed. The prevalence of LBW (<2500 g), severe anaemia (Hb < 8 g/dL) and premature birth was analysed using intention-to-treat (ITT) and per-protocol (PP) analysis.

Results

Data from 1274 singleton pregnancies were analysed (641 in the SP3 and 633 in the SP2 group). The uptake of the intervention appeared to be low. Though the prevalence of LBW in both intervention groups was similar (adjusted Incident Rate Ratio, AIRR = 0.92, 95%CI: 0.69-1.24) in the ITT analysis, the risk of severe anaemia was significantly lower in the SP3 group compared to the SP2 group (AIRR = 0.38, 95%CI: 0.16 - 0.90). The PP analysis showed a trend of reduced risk of LBW, severe anaemia and premature delivery in the SP3 group, albeit the difference between two and three IPTp-SP did not reach statistical significance.

Conclusion

The risk of LBW and severe anaemia tended to be lower in the SP3 group, though this was not statistically significant, probably due to the low uptake of the intervention which reduced the power of the study. Further studies are needed for establishing whether a third SP dose has a real benefit in preventing the negative effects of malaria in pregnancy in settings where transmission is markedly seasonal.

Availability and utilization of malaria prevention strategies in pregnancy in eastern India

Background

Malaria in pregnancy in India, as elsewhere, is responsible for maternal anemia and adverse pregnancy outcomes such as low birth weight and preterm birth.

It is not known whether prevention and treatment strategies for malaria in pregnancy (case management, insecticide-treated bednets, intermittent preventive therapy) are widely utilized in India.

Methods

This cross-sectional study was conducted during 2006-2008 in two states of India, Jharkhand and Chhattisgarh, at 7 facilities representing a range of rural and urban populations and areas of more versus less stable malaria transmission. 280 antenatal visits (40/site) were observed by study personnel coupled with exit interviews of pregnant women to assess emphasis upon, availability and utilization of malaria prevention practices by health workers and pregnant women. The facilities were assessed for the availability of antimalarials, lab supplies and bednets.

Results

All participating facilities were equipped to perform malaria blood smears; none used rapid diagnostic tests. Chloroquine, endorsed for chemoprophylaxis during pregnancy by the government at the time of the study, was stocked regularly at all facilities although the quantity stocked varied. Availability of alternative antimalarials for use in pregnancy was less consistent. In Jharkhand, no health worker recommended bednet use during the antenatal visit yet over 90% of pregnant women had bednets in their household. In Chhattisgarh, bednets were available at all facilities but only 14.4% of health workers recommended their use. 40% of the pregnant women interviewed had bednets in their household. Only 1.4% of all households owned an insecticide-treated bednet; yet 40% of all women reported their households had been sprayed with insecticide. Antimalarial chemoprophylaxis with chloroquine was prescribed in only 2 (0.7%) and intermittent preventive therapy prescribed in only one (0.4%) of the 280 observed visits.

Conclusions

A disconnect remains between routine antenatal practices in India and known strategies to prevent and treat malaria in pregnancy. Prevention strategies, in particular the use of insecticide-treated bednets, are underutilized. Gaps highlighted by this study combined with recent estimates of the prevalence of malaria during pregnancy in these areas should be used to revise governmental policy and target increased educational efforts among health care workers and pregnant women.

Congenital malaria: rare but potentially fatal

Congenital malaria is rare and usually indolent but can be fatal. Mortality risk is high in newborns with Plasmodium falciparum born to nonimmune women, who typically present at birth or soon thereafter. Semi-immune women are less likely to transmit malaria, and their children often become ill weeks after delivery with less severe symptoms. Cases in the USA usually trace to semi-immune immigrant mothers whose last exposure to malaria may have preceded the pregnancy, leading to misdiagnoses. Congenital malaria may be under-recognized in malaria-endemic areas since parasitemia occurring after the first week of life is usually attributed to mosquito transmission. Malaria prophylaxis and the absence of fever during pregnancy do not preclude congenital malaria in a newborn. Quinine plus clindamycin is commonly used to treat P. falciparum congenital malaria, and chloroquine is used to treat other malaria parasites, such as Plasmodium vivax. Severe cases should be managed with intravenous quinine (available as its enantiomer quinidine in the USA) or with intravenous artesunate, which was recently approved for investigational use by the US FDA. Primaquine is not required for infants with congenital P. vivax or Plasmodium ovale, but should be offered to their mothers after excluding G6PD deficiency.

Alpha+ -thalassaemia and pregnancy in a malaria endemic region of Papua New Guinea

The effect of maternal alpha+ -thalassaemia on pregnancy was assessed in the north coastal region of Papua New Guinea (PNG), where malaria is hyperendemic and alpha+ -thalassaemia is extremely common. In a prospective study of 987 singleton hospital deliveries, we correlated maternal alpha-globin genotype with markers of reproductive fitness (age in primigravidae, gravidity, pregnancy interval and the number of miscarriages and stillbirths), Plasmodium falciparum(P. falciparum) infection of the mother and placenta, maternal haemoglobin, preterm delivery and birthweight. The frequency of the -alpha genotype in mothers was 0.61. Markers of reproductive fitness were similar in women with and without alpha+ -thalassaemia. Median haemoglobin concentration during pregnancy and after delivery was about 1.0 g/dl lower in homozygous alpha+ -thalassaemia than in women with a normal alpha- globin genotype (P < or = 0.001). The frequency of placental P. falciparum infection and systemic malaria infection after delivery showed no consistent relationship to alpha-globin genotype. The frequency of preterm delivery and low birthweight did not vary significantly according to maternal alpha-globin genotype. Maternal alpha+ -thalassaemia does not affect reproductive fitness or susceptibility to malaria during pregnancy. Although median haemoglobin concentration was significantly lower in mothers homozygous for alpha+ -thalassaemia than those with a normal alpha-globin genotype, this did not result in an adverse outcome of pregnancy.

The management of sick young infants at primary health centres in a rural developing country

AIMS

To investigate the epidemiology of illness among young infants at remote health clinics in a rural developing country, and to determine risk factors for mortality that might be used as triggers for emergency treatment or referral.

METHODS

Multi-site 12 month observational study of consecutive presentations of infants less than 2 months, and an investigation of neonates who died in one district without accessing health care.

RESULTS

Forty per cent of 511 young infant presentations occurred in the first week of life and most of these in the first 24 hours. Twenty five deaths were recorded: 18 in the health facilities and seven in villages. In addition there were eight stillbirths. Clinical signs predicting death were: not able to feed, fast respiratory rate, apnoea, cyanosis, "too small", "skin-cold", and severe abdominal distension. Signs indicating severe respiratory compromise were present in 25% of young infants; failure to give oxygen therapy was a modifiable factor in 27% of deaths within health facilities. A high proportion of seriously ill young infants were discharged from health facilities early without adequate follow up. A common reason for not seeking care for fatally ill neonates was the perception by parents that health staff would respond negatively to their social circumstances.

CONCLUSIONS

Clinical signs with moderate positive predictive value for death may be useful triggers for emergency treatment and longer observation or urgent referral. The results of this study may be useful in planning strategies to address high neonatal mortality rates in developing countries.

The epidemiology of malaria in Papua New Guinea

Papua New Guinea (PNG) is a patchwork of different ecological zones, inhabited by human populations of exceptional cultural and linguistic diversity. This results in complex variations in vector ecology and malaria epidemiology. Malaria is the main cause of morbidity in many health facilities in lowland areas, but it is absent in much of the highlands. All four human malaria species occur, but endemicity varies widely, with Plasmodium falciparum locally reaching holo-endemic levels that are rarely found outside sub-Saharan Africa. The high frequency of Plasmodium vivax is an important difference to most African situations. PNG is therefore a prime location for studies of interactions between different parasite species, and of the biology of local human genetic adaptation and its implications for malaria morbidity and mortality.

Failure of a chloroquine chemoprophylaxis program to adequately prevent malaria during pregnancy in Koupéla District, Burkina Faso

In West Africa, administration of chloroquine chemoprophylaxis during pregnancy is common, but little is known about its impact on Plasmodium falciparum infection during pregnancy. Therefore, cross-sectional studies in antenatal care clinics (ANCs) and delivery units (DUs) were conducted in Koupéla District, Burkina Faso. Chloroquine chemoprophylaxis was reported by 69% of 597 pregnant women at ANCs and by 93% of 853 women in DUs. P. falciparum peripheral parasitemia was identified in 29% of women at both ANCs and DUs. Placental parasitemia was identified in 22% of delivering women and was strongly associated with low birth weight (LBW) (risk ratio [RR], 1.7; 95% confidence interval [CI], 1.2-2.4) and prematurity (RR, 2.9; 95% CI, 1.6-5.4). In multivariate analysis, use of chemoprophylaxis was not associated with a reduction in the prevalence of placental parasitemia, LBW, or prematurity. Despite the high reported chloroquine chemoprophylaxis coverage, peripheral and placental malaria rates remain high and are associated with known adverse outcomes during pregnancy, including maternal anemia, prematurity, and LBW. Alternative prevention strategies, such as use of insecticide-treated mosquito nets and intermittent preventive treatment with more-effective antimalarials, are needed.

Malaria prevention during pregnancy in unstable transmission areas: the highlands of Madagascar

Malaria transmission in Madagascar is highly variable from one region to the next, and the consequences of the disease on pregnant women and their foetuses are not fully documented. In midwestern Madagascar, the high-transmission lowlands in the west of the country meet the central plateaux, where malaria is unstable because of the high altitude and annual indoor spraying of DDT since 1993. We studied five of the region's main maternity clinics. We began by interviewing sample groups of women of childbearing age living within the vicinity of each clinic. This enabled us to determine the extent to which they had accessed and made use of available maternal health services during pregnancy and delivery, and, hence, to estimate the feasibility of boosting the prophylaxis. We then spent a whole year (from June 1996 to May 1997) observing deliveries at the five clinics in order to gauge the prevalence of placental infection and its consequences on birthweight in various transmission situations. Although only between 2 and 15% of the women said that they had taken prophylaxis during their previous pregnancy, the vast majority had benefited from preventive care: 97% had attended an antenatal visit on at least one occasion and 84% had had the assistance of medical or paramedical staff during delivery, even when their homes were situated relatively far away from the clinic (76%). In total, we observed 1637 deliveries with a mean placental malaria prevalence rate of 8.1%. Individual prevalence rates, however, were found to differ significantly between the maternity clinics situated in the east (minimum 2.1%) and west (maximum 26.2%) of the region. There were also marked variations in line with the seasonal fluctuations in entomological transmission. On the whole, a greater percentage of low birthweights (LBWs) was recorded at the lowland clinics than at the highland ones (17.1% vs. 9.7%), possibly because of the higher malaria infection rate in low altitude areas. On the other hand, the relative risk of LBW linked to placental infection was far greater in the highlands [4.9 (3.3-7.3)] than in the lowlands [1.9 (1.2-3.0)]. Although the rate of placental malaria among women inhabiting the country's central plateaux may be low, it means that transmission--and, hence, the risk of LBW because of placental infection--still persists in spite of the indoor DDT spraying programme. For maximum efficacy, we recommend a combination of vector control (extended to lower altitude areas outside the current OPID zone) and preventive care--i.e. individual chemoprophylaxis--for all highland women during pregnancy.

[Followup of pregnant women in the context of malaria: two case reports]

Whether or not a pregnant women should travel to regions where malaria is highly endemic will always be open to question as no prophlaxis can guarantee complete protection in every case. No chemoprophylaxis is 100% effective or entirely without side-effects, particularly for pregnant women whose immune status provides a favourable environment for the emergence of this parasitosis. The advice given will depend on the country and the region, a possible resistance of the parasite to treatment, the season, the length and circumstances of the stay and individual factors. The choice of treatment is very limited as many therapies are contra-indicated in pregnancy; in addition it is extremely important to give a sufficiently clear explanation concerning precautions and prophylaxis as well as of how a possible bout of malaria should be treated, particularly in case of extended stay.

Evolution of a unique Plasmodium falciparum chloroquine-resistance phenotype in association with pfcrt polymorphism in Papua New Guinea and South America

The mechanistic basis for chloroquine resistance (CQR) in Plasmodium falciparum recently has been linked to the polymorphic gene pfcrt. Alleles associated with CQR in natural parasite isolates harbor threonine (T), as opposed to lysine (K) at amino acid 76. P. falciparum CQR strains of African and Southeast Asian origin carry pfcrt alleles encoding an amino acid haplotype of CVIET (residues 72-76), whereas most South American CQR strains studied carry an allele encoding an SVMNT haplotype; chloroquine-sensitive strains from malarious regions around the world carry a CVMNK haplotype. Upon investigating the origin of pfcrt alleles in Papua New Guinean (PNG) P. falciparum we found either the chloroquine-sensitive-associated CVMNK or CQR-associated SVMNT haplotypes previously seen in Brazilian isolates. Remarkably we did not find the CVIET haplotype observed in CQR strains from Southeast Asian regions more proximal to PNG. Further we found a previously undescribed CQR phenotype to be associated with the SVMNT haplotype from PNG and South America. This CQR phenotype is significantly less responsive to verapamil chemosensitization compared with the effect associated with the CVIET haplotype. Consistent with this, we observed that verapamil treatment of P. falciparum isolates carrying pfcrt SVMNT is associated with an attenuated increase in digestive vacuole pH relative to CVIET pfcrt-carrying isolates. These data suggest a key role for pH-dependent changes in hematin receptor concentration in the P. falciparum CQR mechanism. Our findings also suggest that P. falciparum CQR has arisen through multiple evolutionary pathways associated with pfcrt K76T.

The impact of insecticide-treated bednets on malaria and anaemia in pregnancy in Kassena-Nankana district, Ghana: a randomized controlled trial

The impact of insecticide-treated bednet use on malaria and anaemia in pregnancy was assessed, as a supplementary study, in a major WHO/TDR-supported bednet trial in northern Ghana between July 1994 and April 1995. The study area was divided into 96 clusters of compounds, with 48 clusters being randomly allocated to intervention. All pregnant women were included in the study but the focus was on primigravidae and secundigravidae. 1961 pregnant women were recruited into the study--1033 (52.7%) in the treated bednet group and 928 (47.3%) in the no net group. 1806 (92.1%) had blood taken for malaria microscopy and haemoglobin determination in the third trimester. Pregnancy outcomes were reported for 847 women. The characteristics of women in intervention and control groups were comparable. The odds ratios, with 95% confidence interval (CI), for different study endpoints were, for Plasmodium falciparum parasitaemia--0.89 (0.73, 1.08), for anaemia--0.88 (0.70, 1.09), for low birthweight (LBW)--0.87 (0.63, 1.19), indicating no benefit for treated bednet use. Effective net use by parity varied from 42% in primigravidae to 63% in multigravidae, in spite of free nets and insecticide impregnation. The main reasons for not using a net were warm weather and perceived absence of mosquito biting. Chloroquine use in pregnancy was low and comparable in both groups. Implications of findings for malaria control in pregnancy and further research are discussed.

In vivo sensitivity of Plasmodium falciparum to chloroquine and sulfadoxine-pyrimethamine among schoolchildren in rural Uganda: a comparison between 1995 and 1998

Sensitivity of Plasmodium falciparum to chloroquine and sulfadoxine-pyrimethamine was tested among asymptomatic school children in 1995 and 1998 using a modified in vivo test with examination for parasitaemia on day 0, 2 and 7. Sensitivity (S/RI) to chloroquine in 'urban' areas was found in 42% in 1995 and 62% in 1998 with resistance at the RII/RIII level observed in 58 and 38%, respectively (P<0.01). In 'rural' areas, sensitivity to chloroquine was 76% in 1995 and 72% in 1998 (P=0.6) with resistance at the RII/RIII level observed in 24 and 18%, respectively (P=0.4). Sensitivity to sulfadoxine-pyrimethamine was found in 98 and 99% in 1995 and 1998, respectively. The apparent improvement in sensitivity to chloroquine in 'urban' areas might be due to a different school being included in the two studies. It is concluded that the pattern of sensitivity of P. falciparum to chloroquine and sulfadoxine-pyrimethamine has not changed over a period of 2.5 year.

Chloroquine prophylaxis, iron-folic acid supplementation or case management of malaria attacks in primigravidae in western Uganda: effects on maternal parasitaemia and haemoglobin levels and on birthweight

The effects of weekly chloroquine prophylaxis, daily iron-weekly folic acid supplementation or passive case management on maternal haemoglobin and parasitaemia and on birthweight were examined in primigravidae in a randomized, double-blind placebo-controlled intervention trial in 1996-98 in Hoima District, western Uganda. Iron-folic acid supplementation significantly increased mean birthweight as compared to case management (P = 0.03). Low birthweight (< 2.5 kg) occurred in 2% of babies of women receiving chloroquine prophylaxis for > or = 8 weeks and in 9% in the case management group (RR = 0.36, 95% CI 0.13-1.00, P = 0.009). Parasitaemia at enrolment significantly correlated with low birthweight in the case management group as compared to the intervention groups (P = 0.02). Women in the case management group who were parasitaemia and had haemoglobin levels < 100 g/L at delivery had babies with lower mean birthweight as compared to babies in the other groups (P = 0.04). Low haemoglobin level at enrolment, irrespective of parasitaemia status, was a predictor of low birthweight in the case management group only (P = 0.04). Chloroquine prophylaxis and iron-folic acid supplementation significantly increased maternal haemoglobin levels during pregnancy as compared to case management (P = 0.01 and 0.007, respectively) and the increase correlated to the duration of the intervention.

Growth-stimulating influence of human chorionic gonadotropin (hCG) on Plasmodium falciparum in vitro

In this study, it is reported that human Chorionic Gonadotropin (hCG), being one of the most important hormones of pregnancy, has a growth-stimulating effect on the asexual stages of Plasmodium falciparum in vitro. On the one hand, it is shown that the effect of the hormone is dose-related: The highest growth-rates of Plasmodium falciparum in vitro are achieved, when doses of 8.32 i.u./ml (= 50 i.u. hCG/6 ml) and 16.67 I.U./ml (= 100 i.u. hCG/6 ml) are added to the culture medium. These doses correspond to the physiological peak amounts of hCG between the 9th and 16th week of pregnancy, when parasitaemia also reaches its highest rate. On the other hand, it is shown, that any growth-stimulating effect disappears after inactivation of the hormone by heating at 120 degrees C for 20 minutes. These data support the hypothesis, that hCG does not only possess immunosuppressive properties acting on the response of T-lymphocytes, but also increases the growth of Plasmodium falciparum in vitro. The combination of both effects may explain why malaria still remains one of the most serious complications of pregnancy.

Sensitive ELISA dipstick test for the detection of chloroquine in urine under field conditions

OBJECTIVE

To evaluate a new enzyme-linked immunosorbent assay (ELISA) dipstick test for detecting chloroquine (CQ) in urine in a malaria-endemic region of north-western Namibia.

METHOD

Urine samples from 92 patients attending the outpatient department of Kamhaku Hospital with suspected malaria infection were tested for CQ with both the Dill-Glazko test and the ELISA dipstick test. Results were compared to the history of CQ intake as documented in the patients' health passes.

RESULTS

The dipstick test proved an easy-to-handle and very sensitive tool for the detection of CQ with a lower limit of detection at 120 nmol/l. It showed high agreement with the history of CQ intake within the last 6 months. The specificity in a negative control group was 100%. The Dill-Glazko test was far less sensitive and specific with a lower detection limit of 150 micromol/l.

CONCLUSION

The dipstick test can be used in pharmacological studies to evaluate the use of CQ, and as an inclusion criterion for in vivo and in vitro sensitivity tests, whereas the Dill-Glazko test is appropriate to test compliance during and a few days after CQ intake.

Causes of preterm delivery and intrauterine growth retardation in a malaria endemic region of Papua New Guinea

AIM

To identify causes of preterm delivery and intrauterine growth retardation (IUGR) in a malaria endemic region of Papua New Guinea.

METHODS

Independent predictors of preterm delivery and birthweight in term infants were identified using multiple regression analysis in a prospective study of 987 singleton live births delivered in Madang Hospital.

RESULTS

Overall, Plasmodium falciparum infection of the placenta was associated with a reduction in birthweight of 130 g. Malaria was significantly more common in primigravidae than multigravidae and probably contributed to both preterm delivery and IUGR. Maternal haemoglobin concentrations were significantly lower in malaria infected than noninfected women and reduced haemoglobin was the main determinant of preterm delivery. Poorer maternal nutritional status and smoking were associated with both prematurity and IUGR. Greater antenatal clinic attendance predicted increased birthweight in term infants.

CONCLUSIONS

Protection against malaria during pregnancy, especially in primigravidae, improved nutrition in women and discouragement of smoking would probably reduce both preterm delivery and IUGR. Greater use of existing antenatal clinics might increase birthweight in term infants.

Anaemia- and malaria-attributable low birthweight in two populations in Papua New Guinea

We studied 7300 singleton births in the highlands and 4881 in coastal Papua New Guinea in order to examine the separate contribution of anaemia or malaria to low birthweight. The highland sample was selected from a non-malarious area (Goroka) and the coastal sample from an area with perennial malaria transmission (Madang). There was an approximately three-fold increased risk of low birthweight (< 2500 g) in live-births in Madang compared to Goroka. The prevalence of anaemia in the two areas was strikingly different, with 29.2% of Goroka and 89.0% of Madang women anaemic. There was a trend towards increased low birthweight with decreasing haemoglobin levels in both areas, but this was significant only for Madang. It was assumed that for a given haemoglobin level the increased low birth weight percentage in Madang compared to Goroka was due to malaria exposure, and on this basis relative risk values were estimated for the effect of malaria exposure on low birthweight. Using this approach separate estimates for anaemia and malaria population-attributable risk for low birth weight in Madang were calculated. These indicated that up to 40% of low birthweight babies born in malarious areas may be attributable to malaria and less than 10% attributable to severe anaemia (Hb < 7.0 g dl-1). The magnitude of the malaria effect estimated in this analysis places a high priority on malaria control in pregnancy as a strategy for improving birthweight and child survival.

Malaria in pregnancy

This review summarizes the epidemiology, clinical course, and diagnosis of malaria. The influence of infection during pregnancy upon maternal and neonatal anemia, stillbirth, preterm labor, low birth weight, and congenital malaria is discussed. Options for treatment and prophylaxis during pregnancy are presented.

The impact of a national impregnated bed net programme on the outcome of pregnancy in primigravidae in The Gambia

In 1992, the Gambian national impregnated bed net programme (NIBP) introduced insecticide treatment of bed nets into half of the primary health care villages in The Gambia. One component of the evaluation of this programme was the determination of whether it had any impact on the outcome of pregnancy in primigravidae. From February 1992, 651 primigravidae were recruited into the study. Less than 50% of them used an insecticide-treated bednet. During the rainy season the prevalence of Plasmodium falciparum among primigravidae was lower, fewer babies were classified as premature, and the mean birth weight was higher in villages where treated bed nets were used than in control villages. Therefore, during the rainy season, despite the low use of insecticide-treated bed nets by Gambian primigravidae, the NIBP had some impact on the outcome of pregnancy, particularly on the percentage of premature babies, and this was probably due to the decreased risk of malaria infection achieved during this period.

Adherence of Plasmodium falciparum to chondroitin sulfate A in the human placenta

Women are particularly susceptible to malaria during first and second pregnancies, even though they may have developed immunity over years of residence in endemic areas. Plasmodium falciparum-infected red blood cells (IRBCs) were obtained from human placentas. These IRBCs bound to purified chondroitin sulfate A (CSA) but not to other extracellular matrix proteins or to other known IRBC receptors. IRBCs from nonpregnant donors did not bind to CSA. Placental IRBCs adhered to sections of fresh-frozen human placenta with an anatomic distribution similar to that of naturally infected placentas, and this adhesion was competitively inhibited by purified CSA. Thus, adhesion to CSA appears to select for a subpopulation of parasites that causes maternal malaria.

Malaria and pregnancy: epidemiology, pathophysiology and control options

Extensive research on the epidemiology, pathophysiology, and control of malaria during pregnancy has led to new developments and some controversies. Meanwhile, malaria remains a major environmental factor causing serious pregnancy complications, whose incidence and severity depend on gestational age, parity, and the level of malaria endemicity. There is no cohesive explanation for pregnancy-related immunosuppression, though several pathophysiological hypotheses have been proposed. Furthermore, the emergence and rapid spread of chloroquine resistance has complicated the epidemiology, and the policy on alternative chemoprophylaxis. Chemoprophylaxis is probably the only available option for the control of malaria during pregnancy in Africa. However, the best delivery strategy still has to be established. Daily proguanil is the best chemoprophylactic drug at hand. Its deployment should include constant monitoring for the emergence of proguanil resistance, as well as controlled supervision of the distribution of the drug. New control options, such as the use of insecticide-impregnated bed nets, and intermittent targeted mass chemotherapy, require more operational research before they can be broadly recommended.

Reduced transfer of tetanus antibodies with placental malaria

Placental malaria may limit antibody transfer to the fetus. We compared concentrations of tetanus antibody in paired maternal-cord sera from 224 women living in a malarious area of Papua New Guinea. With heavy placental infection (> 35 parasites per 200 white cells) the average cold tetanus antibody corresponding to a maternal level of 1 IU/mL was 0.18 (95% CI 0.12-0.26); corresponding figures after light (< 35 parasites per 200 white cells) or no infection were 0.23 (0.14-0.34) and 0.82 (0.57-1.21), respectively. About 10% of babies born to mothers with a placenta heavily infected with Plasmodium falciparum may fail to acquire protective levels of tetanus antibody despite adequate maternal antibody.

Women and malaria--special risks and appropriate control strategy

This paper reviews the factors which make non-immune pregnant women particularly vulnerable to falciparum malaria and examines the problems of adequately protecting them in relation to current control strategies. Women are most at risk in areas of high and continuous transmission, particularly during their first pregnancy, and also under conditions of unstable malaria which do not permit immunity to develop. Chemoprophylaxis is recommended for pregnant women in holoendemic and hyperendemic areas in Africa and Papua New Guinea. Chloroquine is safe, but drug resistance problems are beginning to limit its utility. Distribution is a formidable problem in rural areas with a poorly developed health care infrastructure, and research studies reveal widespread ignorance and lack of motivation. In countries in which primary health care systems are fairly well developed, and where malaria transmission is relatively less intense, the emphasis is on early diagnosis and treatment of cases. The assumption is made that women and men have equal access to medical facilities. The preponderance of reported cases among adolescent and adult males in some areas has been attributed solely to the well-known greater occupational risks in some traditionally male activities. Two recent studies, however, suggest that underprivileged women, weighed down by domestic chores, do not readily attend clinics at some distance from home, and therefore are liable to be missed in passive surveillance. It is essential that services within the village should be strengthened, but there are problems in implementation. Lacunae in existing knowledge are discussed.

Field evaluation of the use of an ELISA to detect chloroquine and its metabolites in blood, urine and breast-milk

The evaluation of an enzyme-linked immunosorbent assay (ELISA) for chloroquine and its metabolites in blood, urine and breast-milk is reported. ELISA blood levels, following standard treatment with chloroquine of pregnant and non-pregnant women, showed mean values comparable to other analytical methods. Blood chloroquine concentrations were estimated at day 0, 350-400 ng/ml; day 2, 1000-1500 ng/ml; day 14, 350-400 ng/ml; day 28, 180-350 ng/ml. In a separate sample a significant association was observed between history of chloroquine use in the previous 2 weeks and blood ELISA values (P less than 0.01). Mean ELISA values in breast-milk were higher than in corresponding whole blood samples. High concentrations of chloroquine in urine were observed. There was a weak association of the ELISA of urine and blood samples collected at the same time (P = 0.076). This study confirms the low sensitivity (less than 55%) of the Dill-Glazko test in urine, which is 100-1000 times less sensitive than the ELISA; the latter can detect 10-20 ng chloroquine per ml. A cut-off value for blood positivity 2 weeks following therapeutic drug ingestion was determined (40% ELISA inhibition), which can be used to make decisions about subject selection in drug sensitivity tests or population surveys. There are several advantages with the ELISA under field conditions. These include direct measurement of whole blood concentration; avoidance of problems of urine collection; suitability of finger-prick samples, especially with young children; application to population surveys to monitor drug use; and selection of subjects for drug sensitivity tests and monitoring of blood levels during in vivo tests.

Consequences of maternal anaemia on outcome of pregnancy in a malaria endemic area in Papua New Guinea

The prevalence of anaemia during pregnancy was investigated in relation to parasite and spleen rates of pregnant women living in a defined study area in rural Madang, Papua New Guinea. The effects in pregnancy of anaemia, iron deficiency and malaria on the foetus were investigated. There is a high prevalence of anaemia in this population, with 44% of primigravidae and 29% of multigravidae having severe anaemia [haemoglobin (Hb) less than 8 g dl-1] after 28 weeks gestation. The odds ratio for severe anaemia at 0-16 weeks gestation in pregnant compared to non-pregnant women was 4.7 (P less than 0.0001). Forty-seven per cent of primigravidae and 32% of multigravidae had evidence of iron deficiency with high free erythrocyte protoporphyrin values (greater than 35 micrograms dl-1 whole blood) at antenatal booking. The risk of severe anaemia was significantly associated with splenomegaly and iron deficiency for all gravidae (splenomegaly P less than 0.05; iron deficiency, P less than 0.0002). Hb values at delivery were higher than at first attendance, with the greatest difference between groups malaria-positive at booking and malaria-negative at delivery (primigravidae 1.5 g dl-1, P less than 0.01; multigravidae, 0.7 g dl-1, P less than 0.01), indicating that malaria prophylaxis was an important factor in controlling anaemia. Two Hb groups were defined on the basis of the cut-off at 8 g dl-1, which corresponded to the lower quartile value at booking and delivery. A significantly increased risk of low birthweight was shown for primigravidae with values below 8 g dl-1 (65% v. 27%, P less than 0.025), but the prematurity rate was not significantly increased, indicating that the majority of babies were growth-retarded. Early pregnancy anaemia and iron deficiency were related to the risk of low birthweight in primigravidae. Current parasitaemia at delivery appeared a less important factor, although primigravidae with severe anaemia and parasitaemia at delivery had the lowest birthweights. The extent to which malaria control, using drug treatment and chemoprophylaxis, can reduce the risk of low birthweight will vary in relation to the prevalence and causes of anaemia in women.