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Malaria among pregnant women in Papua New Guinea
by TIvo Mueller, Stephen Rogerson, John Reeder, PNG Institute of Medical Research, P.O. Box 60, Goroka, Papua New Guinea and Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne Australia

PREMA-EU Newsletter, Issue 4, March 2005

Introduction:

The independent state of Papua New Guinea (PNG) is situated on the eastern half of the island of New Guinea . Within the relatively small area of 450,000 km 2 PNG harbours an enormous diversity of environments, from offshore atolls, coastal swamps, and rainforests to mountains > 4,500 m high (Fig. 1). The total human population of about 5.3 millions comprises over 800 different linguistic groups. With good reason, PNG has been called a 'Small Cosmos' ¹

As in highly endemic areas elsewhere, in the PNG lowlands, both prevalence of malaria infection and incidence of morbidity are highest in young children ^{5, 6} and pregnant women ⁷. Malaria is the leading cause of outpatient attendances nationally, the third commonest cause of admission, second commonest cause of death, and causes the greatest burden of disability-adjusted life years, or DALYs (at 4894/100,000 per year). Maternal deaths (to which malaria in pregnancy contributes significantly) are the fifth leading cause of DALYs. With a maternal mortality ratio (MMR) of 370/100,000 childbirth (PNG National Health Plan, 2000) is still among the highest mortality risks for women of child bearing age in PNG. This is particularly true of remote, rural areas where the MMR is estimated to exceed 1000/100,000.

Figure 1. Altitude Zones in Papua New Guinea.
Map based on PNG Digital Elevation Model, PNG Office of Environment & Conservation.

Malaria in pregnancy and maternal health

Precise estimates of the burden of malaria in pregnancy are not available, but regional patterns of birth weight indicated that alongside maternal nutrition and socio-economic factors malaria is a major causative factor for the high prevalence of low birth weight in lowland and coastal parts of PNG8. In Madang and Maprik (see figure 1), where most in depth studies on malaria in pregnancy have been done, mean birth weights reported between 1980 and 2003 range from 2.58 to 2.72 kg in primigravidae (PG) and 2.84 to 3.09 kg in multigravidae (MG) with 21% to 48% and 9% to 19% of babies born to PG and MG, respectively, of low birth weight (< 2500 g) ^{7, 9, 10, 11, 12, 13}. Comparative studies between malaria-endemic coastal PNG and the malaria-free highlands suggested that malaria in pregnancy is responsible for up to 11% of anemia and 40% of low birth weight in coastal areas ¹⁰.

In the only published study looking at the history of infections during pregnancy, Brabin and collegues ⁷ found that the prevalence of malaria infections (at first ANC visit) in primigravidae peaked at 9-16 weeks of gestation (55%). No similar trend was observed for multigravidae. Despite receiving chloroquine prophylaxis at all ANC visits, average prevalence of infections at any ANC visit was 34% in PG, 30% in secundigravidae (SG) and 19% in MG respectively. Several published studies looked at prevalence of malaria infection at delivery. Infection rates were significantly higher in primigravidae reaching over 40% both in peripheral and placental blood in some studies (Table 1).

Table 1: Prevalence of malarial infections at delivery

Placental pathology was not investigated in those studies, but recent work in Madang will report on the prevalence and intensity of histological changes associated with malaria (A Cortes, A Benet in preparation).

In a pooled sample that contained roughly equal numbers of PG, SG and MG, Allen and co-workers ¹³ found that peripheral and placental infection at delivery were associated with a 128 g and 145 g decrease in birth weight respectively. Other PNG studies lacked sufficiently large samples sizes to find significant differences in birth weights in relation with malaria infection status.

Anaemia is very common feature in pregnant women in many parts of lowland PNG. In 1986-88, 89% of women delivering at the major referral hospital in Madang had Hb < 11 g/dl and 19% of PG and 17% of MG had severe anaemia, i.e. haemoglobin < 7g/dl ¹⁰. Haemoglobin values measured at first booking at a rural health centre in Madang were significantly lower in both PG (8.6 g/dl) and MG (8.7 g/dl) compared to non-pregnancy controls (10.4 and 10.2 g/dl respectively), despite similar levels of iron deficiency, with a tendency for Hb levels to decrease with increasing length of gestation and to be lower in PG with concurrent malaria infection (-0.7g /dl, p=0.15) ⁹. Up to 40% of women showed signs of iron deficiency. With CQ prophylaxis and treatment for severe anaemia Hb levels in these women recovered to 9.6 g/dl in PG and 9.3g/dl in MG at delivery with no significant difference between malaria positive and negative women. Perhaps related to the addition of iron/folate supplementation to the national treatment guidelines, haemoglobin values during pregnancy and at delivery have been higher in recent studies ¹³, and the proportion of women severely anaemic (Hb < 7 g/dl) at delivery decreased to 13% in 2002/3 (Cortes, Benet et al., in prep).

Anaemia (Hb < 8 g/ld) was significantly associated with a decrease in birth weight in PG (-281 g) but not in MG (- 84 g) ⁹. However, in depth studies showed that anaemia is mainly with linked to an increased risk of preterm delivery (OR: 1.4 100g -1) rather than a decrease in birth weight in term infants ¹³.

Although non-falciparum malaria is common in PNG, little is know about its effect on pregnant mothers and their babies. In a study in the mid 1980’s the prevalence of P. vivax was lower in pregnant mothers attending ANC7 (and under CQ prophylaxis) than in the postnatal period, but this is likely be to more a reflection of the high effectiveness of CQ prophylaxis against non-falciparum malaria rather than of reduced risk in pregnancy. However, further in-depth studies are needed to assess the contribution of non-falciparum malaria to malarial in pregnancy in PNG.

There have only been a few studies on congenital malaria, but the limited data indicated that transplacental transfer of P. falciparum parasites is common. In a small study in Madang umbilical cord infection was found in 7 of 15 (47%) children born to women with parasitaemia at time of delivery ^15. Four of these children also had detectable peripheral parasitaemia. Little is know about transplacental transfer of other malaria species, although at least one case of a symptomatic P. vivax infection acquired in utero has been described ¹⁶.

Very little is known about the problem of malaria in non-immune women living in areas of low endemicity such as the highlands. The overall burden of malaria in pregnancy is likely to be low as indicated by the substantially higher haemoglobin levels and lower rates of LBW in highland areas ¹⁰. However, due to low immune status acquired infections are more likely to be severe and mortality rates in pregnant mothers with severe malaria can be as high as 50% ¹⁷.

The detrimental effects of malaria in pregnancy are compounded by low rates of antenatal coverage and supervised deliveries. Nationally, only 2/3 of women receive any antenatal care during their pregnancy and 44% of deliveries are supervised. However, there are large regional variations. Antenatal coverage can drop below 50% and the proportion of supervised deliveries falling to as low as 10-15% in some rural districts of the country (2000 PNG National Health Plan).

Two factors contribute to this low antenatal coverage and low rate of supervised deliveries: limited access to health care and strong customary beliefs surrounding childbirth. In many rural parts of PNG women will have to walk for several hours through often difficult terrain to reach the nearest health centre. With a decline in mobile ANC clinic coverage access to both ANC and delivery services is therefore severely limited. Unless obstetric complications such as breech presentation are detected at a previous ANC clinical visit and the women is admitted, many women will not be able to reach the HC once labour has started regardless of complications. Staffing levels and morale are other important obstacles to good clinical care.

In many parts of PNG even many women living within reasonable distance of well run health centres still prefer to deliver at home. In many PNG cultures childbirth is the focus of many customary beliefs and restrictions. Child birth, like menstruation, is often believed to have a ‘polluting’ influence, in particular on men, and assistance to women in labour is often limited. In some places women in labour will go to the bush and deliver their babies completely unattended. In addition, there are strong beliefs associated with the disposal of placentas that may also inhibit women from delivering at a health facility.

Policy, Prevention and Treatment

Both malaria and safe motherhood have been identified as priority areas in the 2000 PNG National Health Plan. The plan calls for a reduction of maternal mortality to 260/100,000 and LBW to < 10%, while at the same time aiming to increase ANC coverage to 90% and proportion of supervised deliveries to 70%. The goals for maternal mortality and LBW will not be reached without effective control of the detrimental effects of malaria in pregnancy.

Given the problems with access to adequate health care and the reluctance of mothers to deliver at health centres, preventive interventions have to be the main approach to improving the health of pregnant mothers and their babies.
The current PNG National treatment policy prescribes a treatment course of 1st line antimalarial treatment (currently chloroquine and SP) at first ANC contact followed by weekly chloroquine prophylaxis and iron and folate supplementation. However, the usefulness of chloroquine prophylaxis is questionable, given the high levels of resistance to chloroquine2 in PNG and well know problems of compliance. Even in the mid 1980s chloroquine prophylaxis had little effect on malaria infection rates at delivery ^{9, 13, 18}.although it was associated with increased haemoglobin levels ^{9, 13} and decreased in risk of pre-term deliveries ¹³. Thus, in the absence of information regarding alternative approaches, the policy is continuing today.

The use of insecticide treated bed nets (ITNs) during pregnancy is also advised as part of the national guidelines, but to date no special bed net distribution for pregnant mothers is in place. In many areas ITNs can be bought from HCs but supplies are unreliable and prices often a deterrent. This situation is expected to change in the near future, as PNG has secured a grant for the Global Fund for Aids, Tuberculosis & Malaria that will allow the provision of long-lasting ITNs to all people living in malarious areas in PNG. Monitoring the impact of this programme on adverse pregnancy outcomes will be an important part of assessing its effectiveness.

Current treatment guidelines for malaria in pregnancy indicate the use of CQ and SP for uncomplicated disease, oral quinine with SP for treatment failure, and parenteral quinine for severe malaria in pregnancy. The clinical efficacy of CQ plus SP against P. falciparum is still high (93%, Marfurt, Mueller et al. unpublished results), however the rising levels of parasitological failure (up to 15%) indicates that these drugs may be nearing the end of their life span sooner rather than later. Although not yet part of the official treatment guidelines for pregnancy malaria, artesunate and IM artemether are “third line” treatments for malaria in non-pregnant people, and are regularly used to treat women in their 3rd trimester admitted to hospitals with a presumptive diagnosis of malaria.

Future research needs

The high levels of morbidity and mortality indicate the current polices for prevention and treatment of malaria in pregnancy are inadequate and new or improved approaches are needed. Research into new options for the prevention of malaria in pregnancy such as intermittent preventive treatment (IPTp), the better integration of ITNs and/or new and improved forms of prophylaxis is of high priority. In the medium term, new drugs for treatment of malaria in pregnancy will be needed.

Table 2: Special characteristics for research into malaria in pregnancy in PNG

The above interventions will however only be successful if they can fit into local circumstances, customs and beliefs. Operational research into modes of delivery of maternal health interventions, in particular on ways of increasing coverage of ANC and supervised deliveries as well as a better understanding of women’s perceptions of their own health are thus needed if the high levels of maternal mortality, severe maternal anaemia and low birth weight delivery are to be reduced.

The special epidemiology of malaria, genetic and cultural diversity as well as imminent changed to malaria control policies makes PNG an ideal location to conduct in depth studies into different aspects of malaria in pregnancy (Table 2). Building on earlier work the PNG Institute of Medical Research (PNGIMR) is committed to tackling the challenges posed by the high levels of malaria and maternal mortality in the country and thereby contributing to a better and healthier future for all PNG women. The unique status of the PNGIMR as both a research institute and an advisory body to the PNG National Health Department facilitates rapid translation of research findings into national health policies.

Cited references:

1. Attenborough RD, Alpers MP, 1992. Human Biology in Papua New Guinea. Oxford: Clarendon Press.
2. Muller I, Bockarie M, Alpers M, Smith T, 2003. The epidemiology of malaria in Papua New Guinea. Trends Parasitol 19: 253-9.
3. Burkot TR, Graves PM, Paru R, Wirtz RA, Heywood PF, 1988. Human malaria transmission studies in the Anopheles punctulatus complex in Papua New Guinea: sporozoite rates, inoculation rates, and sporozoite densities. Am.J.Trop.Med.Hyg. 39: 135-144.
4. Mehlotra RK, Kasehagen LJ, Baisor M, Lorry K, Kazura JW, Bockarie MJ, Zimmerman PA, 2002. Malaria infections are randomly distributed in diverse holoendemic areas of Papua New Guinea. Am. J. Trop. Med. Hyg. 67: 555-62.
5. Genton B, Al Yaman F, Beck HP, Hii J, Mellor S, Narara A, Gibson N, Smith T, Alpers MP, 1995. The epidemiology of malaria in the Wosera area, East Sepik Province, Papua New Guinea, in preparation for vaccine trials. I. Malariometric indices and immunity. Ann Trop Med Parasitol. 89: 359-376.
6. Cattani JA, Tulloch JL, Vrbova H, Jolley D, Gibson FD, Moir JS, Heywood PF, Alpers MP, Stevenson A, Clancy R, 1986. The epidemiology of malaria in a population surrounding Madang, Papua New Guinea. Am.J.Trop.Med.Hyg. 35: 3-15.
7. Brabin BJ, Ginny M, Alpers M, Brabin L, Eggelte T, van der Kaay HJ, 1990. Failure of chloroquine prophylaxis for falciparum malaria in pregnant women in Madang, Papua New Guinea. Ann.Trop.Med.Parasitol. 84: 1-9.
8. Muller I, Betuela I, Hide R, 2002. Regional patterns of birthweight in Papua New Guinea in relation to diet, environment and socio-econimic factors. Annals of Human Biology 29: 74-88.
9. Brabin BJ, Ginny M, Sapau J, Galme K, Paino J, 1990. Consequences of maternal anaemia on outcome of pregnancy in a malaria endemic area in Papua New Guinea. Ann.Trop.Med.Parasitol. 84: 11-24.
10. Brabin B, Piper C, 1997. Anaemia- and malaria-attributable low birthweight in two populations in Papua New Guinea. Ann.Hum.Biol. 24: 547-555.
11. Desowitz RS, Alpers MP, 1992. Placental Plasmodium falciparum parasitaemia in East Sepik (Papua New Guinea) women of different parity: the apparent absence of acute effects on mother and foetus. Ann.Trop.Med.Parasitol. 86: 95-102.
12. Oppenheimer SJ, Macfarlane SB, Moody JB, Harrison C, 1986. Total dose iron infusion, malaria and pregnancy in Papua New Guinea. Trans.R.Soc.Trop.Med.Hyg. 80: 818-822.
13. Allen SJ, Raiko A, O'Donnell A, Alexander ND, Clegg JB, 1998. Causes of preterm delivery and intrauterine growth retardation in a malaria endemic region of Papua New Guinea. Arch.Dis.Child Fetal Neonatal Ed 79: F135-F140.
14. Brabin BJ, Ginny M, Sapau J, Galme K, Paino J, 1990. Consequences of maternal anaemia on outcome of pregnancy in a malaria endemic area in Papua New Guinea. Ann Trop Med Parasitol 84: 11-24.
15. Lehner PJ, Andrews CJA, 1988. Congenital Malaria in Papua-New-Guinea. Transactions of the Royal Society of Tropical Medicine and Hygiene 82: 822-826.
16. Schuurkamp GJ, Paika RL, Spicer PE, Kereu RK, 1986. Congenital malaria due to Plasmodium vivax: a case study in Papua New Guinea. P.N.G.Med.J. 29: 309-312.
17. Lalloo DG, Trevett AJ, Paul M, Korinhona A, Laurenson IF, Mapao J, Nwokolo N, DangaChristian B, Black J, Saweri A, Naraqi S, Warrell DA, 1996. Severe and complicated falciparum malaria in melanesian adults in Papua New Guinea. American Journal of Tropical Medicine and Hygiene 55: 119-124.
18. Mola GL, Wanganapi A, 1987. Failure of chloroquine malaria prophylaxis in pregnancy. Aust.N.Z.J.Obstet.Gynaecol. 27: 24-26.

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