The epidemiology of malaria in the Papua New Guinea highlands: 1. Western Highlands Province

Despite a resurgence of malaria in many Papua New Guinea highlands and highlands fringe areas after the cessation of control activities in the early 1980s the malaria situation in these areas has received little attention. A series of cross-sectional surveys were therefore carried out to provide accurate and up-to-date information on the prevalence of malaria and the risk of epidemics and to propose adequate malaria control strategies. Studies in 24 villages in Western Highlands Province found the prevalence of malarial infections to be strongly correlated with altitude, ranging from 1.6% at altitudes of 1500-1800 m to over 30% in villages below 900 m. Malaria outbreaks were observed at the end of the rainy season. All four human malaria species were present with P. falciparum infections clearly dominating. The relative importance of P. vivax increased with altitude, while both P. malariae and P. ovale were rare. Many infections were of low density. While malaria is an important source of febrile illness in endemic areas below 1500 m altitude, only few observed or reported fevers are due to malarial infections in higher, nonendemic areas. Rates of enlarged spleens, mean haemoglobin levels and the prevalence of anaemia (Hb <7.5 g/dl) were strongly linked to the level of malaria found in each community and were associated with both altitude and concurrent malarial infection. Based on the survey results, areas of different malaria epidemiology are delineated and options for control in each area are discussed.     

The epidemiology of malaria in the Papua New Guinea highlands: 4. Enga Province

Of all Papua New Guinea provinces, Enga has the largest proportion of people living at altitudes that preclude malaria transmission. However, the first systematic surveys in 1979 showed that malaria was endemic in lower-lying valleys to the north and east of the province. A series of new surveys conducted in both wet and dry seasons showed that these areas remain the main malaria focus in Enga. However, over the last 25 years the risk of malarial infections has increased substantially in areas < 1200 m (from 10% to 37-41%). In these low-lying areas people acquire substantial antimalarial immunity and most infections are asymptomatic. However, people in villages in these areas had significantly lower mean haemoglobin levels (13.0 vs 14.0 g/dl, p < 0.001) than in areas above 1200 m, where overall prevalence rates (0-9%) have not changed much. In areas between 1200 and 1600 m epidemics with parasite prevalence rates in excess of 20% have been found to occur. Malaria was a significant cause of febrile illness only in endemic areas or during outbreaks. Although rarely used, sleeping under a bednet was associated with a significant reduction in risk of malaria infection (adjusted OR = 0.45, p = 0.01). On the other hand, sleeping in garden houses away from the main villages increased the risk of malaria infection (adjusted OR = 1.6, p = 0.03). Malaria control in outlying, malarious areas of Enga province could therefore be based on the distribution of long-lasting impregnated bednets, while at the same time addressing the additional risks posed by the high mobility of many of these populations through targeted health education.     

The epidemiology of malaria in the Papua New Guinea highlands: 3. Simbu Province

Two very distinct malaria zones can be found within Simbu Province. The north of the province is characterized by the absence or very low level of local malaria transmission, but there is a considerable risk of epidemics prevalent in the lower-lying parts. During non-epidemic periods, parasite prevalence was usually under 5%, with similar frequencies for Plasmodium falciparum and P. vivax (47% each), and malaria was an only minor source of febrile illness. During epidemics, however, 13-36% of people were infected, predominantly with P. falciparum (64%), and high levels of severe morbidity were present. In south Simbu malaria is clearly endemic with an overall prevalence of 35%, combined with a strong age-dependence of infections, low haemoglobin levels, high rates of enlarged spleen and moderate to severe anaemia (haemoglobin level < 7.5 g/dl) in children. The malaria epidemiology in south Simbu is thus more similar to the lowlands than to other highlands areas. Epidemic prevention, surveillance and response in the north, and bednet distribution and strengthening of curative services in the south, are therefore the priorities for malaria control in Simbu Province.     

Complex patterns of malaria epidemiology in the highlands region of Papua New Guinea

A cross-sectional malaria survey of the Pabrabuk area in the Western Highlands Province found that all 4 human malaria species were present in a single village, with an overall parasite prevalence rate of 27%. Plasmodium falciparum was the most frequently detected infection (14%) followed by P. vivax (11%), P. malariae (5%) and P. ovale (3%). 10 of the 51 infections were mixed. Anopheles punctulatus was the most frequent vector species in the area, but both An. farauti no. 6 and An. karwari were also present in low numbers. This diversity in both parasite and vector populations indicates that complex malaria patterns are found in Papua New Guinea even at the moderate transmission levels found in low-lying inter-montane valleys.     

Diarrhoea morbidity in children in the Asaro Valley, Eastern Highlands Province, Papua New Guinea

A morbidity study of diarrhoea covering 1926 children aged less than 5 years was carried out in Goroka town and the Lowa and Asaro Census Divisions, Eastern Highlands Province between 1986 and 1989. The study involved weekly demographic surveillance of the total population and morbidity surveillance of children by lay reporters who enquired about the presence or absence on any of the preceding 8 days of a range of symptoms associated with diarrhoeal and respiratory diseases. A three-day symptom-free period was used to define distinct episodes of diarrhoea. The average number of episodes/child-year for all children in the study population was 3.0. Boys suffered a significantly higher incidence of diarrhoea under 48 months of age than girls (4.4 episodes compared to 3.6/child-year). Incidence was highest among those aged 6-17 months (5.5/child-year) with a rapid decline after age 35 months. Incidence of diarrhoea was highest in the more remote Asaro Census Division and was higher in periurban areas than in Goroka town. Incidence also varied significantly between villages, some villages experiencing up to 10 times the incidence of diarrhoea found in Goroka town. The incidence of diarrhoea was significantly higher in January than at other times of year. Duration of diarrhoea varied with age, the longest duration being an average of 4.7 days in the 12-17 months age group. In order to reduce diarrhoea morbidity, it is necessary to improve access to water, encourage improved hygiene practices and breastfeeding and warn people about the risks of sleeping with pigs.     

Village rural water supplies in the Western Highlands Province of Papua New Guinea

The 1980's have been declared the "International Water Supply and Sanitation Decade". The Papua New Guinea (PNG) Government has committed itself to spending K2.5 million between 1982-1985 on rural water supplies. The experience for such a programme in the Western Highlands is reviewed. Between 1975 and June 1981 there were 101 installation, 69 of which were inspected. Of these, 40.6% were working. Within one year 40% had broken down; after 4 years, 90% had broken down. Contributing factors to break downs were; the use of a cheap and inefficient hand pump on wells; use of plastic rather than metal pipes in reticulated water supplies; weaknesses in the design of reticulated supplies; and difficulties with regular maintenance. It is recommended that the government take steps to solve these problems before it commits itself to a significantly increased expenditure on rural water supplies.     

Sex Workers' Sexual Health and Peer Education Project in Goroka, Eastern Highlands Province, Papua New Guinea

We conducted a survey among female sex workers in Goroka, Eastern Highlands Province, Papua New Guinea to evaluate the frequency of sexually transmitted disease (STD) symptoms they suffered, their STD and HIV (human immunodeficiency virus) transmission knowledge and health-seeking behaviours, the forms that their HIV risk perception took, and the types and quantities of educational resources to which they had access and in fact used. This survey was a part of a larger study of sex workers that was carried out in two other cities, Lae, the capital of Morobe Province, and Port Moresby, the nation's capital. We interviewed 190 self-identified female sex workers who had been recruited between January 1999 and October 1999 through peer-mediated contacts. In an average one-week period, the women had intercourse with two customers, two to three times, and one boyfriend once or twice. In the surveyed group, 83% of the women had a history of symptomatic STDs and 73% had gone to an STD clinic for treatment. Of the women who used condoms at all, 7% used them each time they had sex with clients, but only 3% used them each time they had sex with steady partners. The remaining 93% of the women used condoms on some occasions or not at all. Most women (72%) knew about male-female transmission of HIV, but fewer cited other sexual and non-sexual modes of transmission. The majority of the women (71%) felt that they were of low or unknown risk of acquiring HIV infection. When asked where or to whom they would go when concerned about AIDS (acquired immune deficiency syndrome) or STDs, most women (93%) said that they would go to a health care provider. Evaluating the sex workers' understanding of STDs and HIV has been essential in designing education and intervention projects so as better to address the future morbidity and mortality associated with STDs and AIDS.     

Barriers to measles immunization: the beliefs and attitudes of caregivers in Goroka, Eastern Highlands Province, Papua New Guinea

In Papua New Guinea, measles remains a public health problem and the majority of measles cases occur in non-immunized children. In Goroka, measles vaccine coverage for the 9-month-old group was 44%. The parents or caregivers are important in measles prevention as children's immunization depends on their compliance. This study aimed to determine the factors that hinder caregivers from having their children vaccinated for measles prevention in the Goroka District, Eastern Highlands Province. A cross-sectional study was conducted in July-August 2003, using pre-constructed questionnaires and interviews. There was a total of 120 respondents who were caregivers or parents of children whose ages ranged from 6 to 12 months and who attended health care centres where immunization services were provided. The main reasons for not bringing their children to clinic for immunization were: limited access to health centres, especially to maternal and child health (MCH) clinics; too long a waiting time at the clinic; concern that too many injections were being given to their children; the side-effects of the vaccine; being sent away and asked to come back the next day for immunization; and a bad reception from health workers. Funerals or election-related events in the area also affected the attendance at the clinic. In order to improve the vaccine coverage, the use of a mobile MCH clinic should be re-established. Health workers should utilize the opportunities to pass on necessary information on immunization to caregivers, as well as being mindful to use communication that will prevent misunderstanding by the mothers. It is important for all health workers to recognize that their performance and attitude can greatly improve the overall vaccine coverage in Papua New Guinea.     

The spread of chloroquine-resistant falciparum malaria in Papua New Guinea.

Two cases of chloroquine-resistant Plasmodium falciparum malaria have been reported from eastern Papua New Guinea in order to alert the medical profession about the spread of resistant strains throughout that territory.     

Analyses of vegetables from the highlands of Papua New Guinea

Ten vegetable foods of the highlands were analysed for crude protein, amino acids and trypsin inhibitor. Pandanus nut, lima bean, fern, greens, pitpit and choko had good to acceptable crude protein contents and the proteins of fern, pitpit, Rungia klossii and Indian mustard were of good quality. Lima beans had a very high content of trypsin inhibitor and all others had small or zero amounts, including fern, which is used at pig feasts and hence does not contribute to pig bel.     

HLA and nonspecific polyarthritis in the highlands of Papua New Guinea

We have studied the HLA profile of a series of 49 patients (32 men, 17 women) presenting with asymmetric polyarthritis to the Goroka Base Hospital, Papua New Guinea. Antigens A11 and B27 were found to be significantly increased in patients when compared with a control sample of 100 healthy Papua New Guinean highlanders. Significant negative associations were also recorded with A24[A9] and Bw22. None of the patients studied presented with the complete triad of Reiter's disease although 6 patients, all men, had some extraarticular symptoms. On the basis of these additional symptoms, the 6 patients were diagnosed to have an incomplete form of Reiter's disease and were excluded from further comparisons. In the remaining 43 patients, who fit the nonspecific category that has been called tropical polyarthritis, B27 was present in 20.9% of the cases, which was not significantly different from the control frequency of 11.0%. But the positive association with A11 was still found in the nonspecific arthritis cases. Our data do not support the concept that the patients included in this study constitute a single diagnostic category which is related to Reiter's disease. It is suggested that these patients be regarded as suffering from nonspecific polyarthritis of unknown, probably multiple, aetiology, until further more specific diagnostic entities can be determined.     

Rotavirus infection in young children in the highlands of Papua New Guinea

Rotavirus infections were detected by electron microscopy examinations in 54 of 66 children (82%) with acute gastroenteritis which necessitated admission to hospital during April to July, 1979, in the Highlands of Papua New Guinea. Longitudinal epidemiological studies may confirm rotavirus infections to be more important aetiolgical agents of childhood gastroenteritis in this region than in many other countries studied to date.     

Lymphocyte subsets in Eastern Highlanders of Papua New Guinea.

Lymphocyte subsets were enumerated in Papua New Guinean children, adolescents and adults from the Eastern Highlands and comparative groups of age-matched expatriates living in the Goroka area. From the age group under 6 months until adolescence, the numbers and percentages of CD8-positive (suppressor/cytotoxic) T cells were higher in Papua New Guinean highlanders than in expatriates. In highland subjects over 35 years of age, both CD8-positive and CD4-positive (helper/inducer) T-cell numbers were lower than in younger subjects whereas in expatriates their numbers remained the same. Highlanders over the age of 35 years had fewer T cells (including CD8-positive T cells) than expatriates. Helper/suppressor ratios were lower in highlanders than in expatriates from the age group under 6 months to the 20-30 year age group; the lowest ratio was found at 10-15 years of age, when the mean was 0.95.     

Mortality rates and the utilization of health services during terminal illness in the Asaro Valley, Eastern Highlands Province, Papua New Guinea

Between 1980 and 1989 we carried out fortnightly demographic surveillance in a random sample of people living in Goroka town, periurban areas and rural areas in the Lowa and Asaro Census Divisions, all within 1 1/2 hours' drive of the town in the Asaro Valley, Eastern Highlands Province. Cause of death was determined by verbal autopsy supplemented by any available health service information. Crude death and birth rates were 10 and 32 per 1000 person-years, respectively, in 59,906 person-years at risk. The standardized mortality ratio increased with increasing distance from town. Life expectancy at birth was 57 years for males and 55 years for females. The stillbirth rate was 19 per 1000 births, neonatal and infant mortality 21 and 60 per 1000 livebirths, respectively, and 1-4-year mortality 9 per 1000 person-years. Maternal mortality was 3 per 1000 births. Neonatal and infant mortality were respectively 7 and 3 times as high in Asaro Census Division as in Goroka town. Acute lower respiratory tract infections accounted for 22% of all deaths, chronic obstructive lung disease 10%, trauma 8% and gastroenteritis/dysentery 7%. 76% of deaths occurred at home and 44% of people who died had no treatment during their terminal illness. Health services were used most frequently by urban dwellers and by the young. To reduce mortality, a political commitment to provide functioning health services in rural areas is needed; regular supervision of health staff, ensuring the safety of staff and their families, availability of antibiotics as near people's homes as possible and regular mobile maternal and child health clinics are essential. Health education should include recognition of signs of severe disease and the importance of seeking treatment early. In view of high maternal and neonatal mortality, user fees should be waived for pregnant women.     

Emerging asthma in the Okapa district of the Eastern Highlands province of Papua New Guinea: the problem and its implications

This study found a high prevalence of asthma in 1800 residents of eight villages of the South Fore people in the Eastern Highlands of Papua New Guinea. The prevalence in adults (7%) is amongst the highest reported in the world, but the disease is practically absent in children. Whilst the features of the disease are similar to those previously described for asthma in Papua New Guineans, the prevalence is very much higher. Evidence from medical officers and the indigenous population indicates that the disease has only become noticeably prevalent in this area within the last decade, about two decades after first contact with Europeans. The asthma is associated with considerable impairment of resting lung function and is an important source of morbidity and more recently of mortality in these villages. Treatment is unsatisfactory because of both logistic and financial constraints. There is an urgent need for further epidemiological studies of asthma in both the Eastern Highlands Province and elsewhere in the country.