Malaria morbidity in Papua Indonesia, an area with multidrug resistant Plasmodium vivax and Plasmodium falciparum

Abstract

Background: Multidrug resistance has emerged to both Plasmodium vivax and Plasmodium falciparum and yet the comparative epidemiology of these infections is poorly defined.

Methods: All laboratory-confirmed episodes of malaria in Timika, Papua, Indonesia, presenting to community primary care clinics and an inpatient facility were reviewed over a two-year period. In addition information was gathered from a house-to-house survey to quantify the prevalence of malaria and treatment-seeking behaviour of people with fever.

Results: Between January 2004 and December 2005, 99,158 laboratory-confirmed episodes of malaria were reported, of which 58% (57,938) were attributable to P. falciparum and 37% (36,471) to P. vivax. Malaria was most likely to be attributable to pure P. vivax in children under one year of age (55% 2,684/4,889). In the household survey, the prevalence of asexual parasitaemia was 7.5% (290/3,890) for P. falciparum and 6.4% (248/3,890) for P. vivax. The prevalence of P. falciparum infection peaked in young adults aged 15-25 years (9.8% 69/707), compared to P. vivax infection which peaked in children aged 1 to 4 years (9.5% 61/642). Overall 35% (1,813/5,255) of people questioned reported a febrile episode in the preceding month. Of the 60% of people who were estimated to have had malaria, only 39% would have been detected by the surveillance network. The overall incidence of malaria was therefore estimated as 876 per 1,000 per year (Range: 711-906).

Conclusion: In this region of multidrug-resistant P. vivax and P. falciparum, both species are associated with substantial morbidity, but with significant differences in the age-related risk of infection.

Figure 1

Location of study area in Timika, southern Papua, Indonesia.

Figure 2

Age-stratified proportions of total patient workload diagnosed with pure P. falciparum (dark bars), pure P. vivax (light bars) and mixed falciparum and vivax infections (white bars) at each type of healthcare facility. Footnote: For each age group the lower number above the column is the total number of patients reviewed (= microscopy examinations in community clinics, or patients seen or admitted at the hospital) and the upper number represents the total number of patients with malaria.

Figure 3

Population by age group and gender in the community household survey.

Figure 4

a) Age-stratified parasitaemia prevalence rates in the household survey for P. falciparum, P. vivax and mixed infections for febrile (dark bars) and afebrile respondents (light bars). b) Proportions of all parasitaemic cases attributable to P. falciparum, P. vivax and mixed infections for Papuans (dark bars) and Non-Papuans (light bars).