Two clusters of Plasmodium knowlesi cases in a malaria elimination area, Sabang Municipality, Aceh, Indonesia

Abstract

In malaria elimination areas, malaria cases are sporadic and consist predominantly of imported cases. Plasmodium knowlesi cases have been reported throughout Southeast Asia where long-tailed and pig-tailed macaques and Anopheles leucosphyrus group mosquitoes are sympatric. The limitation of microscopic examination to diagnose P. knowlesi is well known. In consequence, no P. knowlesi case has previously been reported from routine health facility-based case finding activities in Indonesia. This report describes two clusters of unexpected locally acquired P. knowlesi cases found in an area where Plasmodium falciparum and Plasmodium vivax infection had been eliminated in Sabang Municipality, Aceh, Indonesia. The difficulties in diagnosis and response illustrate challenges that Southeast Asian countries will increasingly face as the formerly common malaria parasites P. falciparum and P. vivax are gradually eliminated from the region.

Keywords: Aceh; Indonesia; Malaria diagnosis; Malaria elimination; Plasmodium knowlesi.

Fig. 1

a Distribution of Plasmodium knowlesi cases based on estimated date of first presentation of symptoms. Initials and case number of patients correspond with those in Table 1. 15 PCR confirmed Pk cases and two suspected Pk cases (SF and RV from Table 1) are mapped. Red cross: position of health facilities in Sabang including both Primary Health (PHC) and hospitals (RSUD and RSAL). Dotted red ellipse: cluster of cases at Iboih Village. Dotted purple ellipse: cluster of cases in a family at Ie Meulee Village. b Position of Sabang within Aceh Province. c Position of Sabang within the Indonesian archipelago and Malaysia

Fig. 2

Timeline of events for two clusters of Plasmodium knowlesi cases in Sabang. For all cases case investigations and reactive case detection were performed; followed by IRS and LLIN distribution to index case’s house. On 27–29 December 2014, IRS and mass LLIN distribution was done for all residents of Iboih village. Yellow box: passive case detection; green box: reactive case detection; blue box: mass screening and treatment; white box: response of Municipal Health Office. Bold letters: initial of patient. Hashtag number in bracket: case ID number. Dotted red rectangle: a cluster at Iboih Village. Dotted purple rectangle: a family cluster at Ie Meulee Village. Dx: diagnosis, PHC: Primary Health, CI: case investigation, RACD: reactive case detection, MST: mass screening and treatment, LLINs: Long-lasting insecticide-treated nets, IRS: indoor residual spraying