A first case investigation of Plasmodium knowlesi, Saraburi Province, Thailand, June 2017

Abstract

Background: Plasmodium knowlesi is a simian malaria parasite. In May 2017, The Office of Disease Prevention and Control Region 4 received a case notification from Bureau of Vector Borne Diseases, Department of Disease Control. The first P. knowlesi patient lived in Saraburi admitted in hospital of Tropical Medicine, Mahidol University. An Investigation was initiated to verify diagnosis, described epidemiological characteristics, determine sources of infection and risk factors, and implement appropriate control measures.
Methods: The descriptive epidemiology study was conducted to review malaria cases (ICD-10: B50-B54) in Muaklek and private hospitals in Saraburi from 2008 to 2017. Data collected by case interview about history of illness and behavior risk factors. A case definition was a person living in Village Z, Mittrapap Sub-District, Muaklek District, Saraburi and developed fever, chill and history of wandering around the forest or malaria infected areas from December 1, 2016 to June 21, 2017. Blood sampling collected by thick and thin blood smear and PCR for P. knowlesi. Furthermore, the entomologic study was determined the potential risk factor and identified mosquito species.
Results: All 37 malaria cases in such hospitals, the sex ratio (female per male) was 2.4 : 1. Average age was 29±15.04. The most nationality was Thai (68.0%), P. vivax and unspecified malaria was 78.4% and 13.5%, respectively. The most malaria cases in Mittrapap Sub-District (35.1%). On January 23, 2016, a 46-year-old Thai male patient, developed symptom as fever, chill, myalgia and fatigue in this area. Septic shock and severe vivax malaria was diagnosis and admitted ICU with early treated by Chloroquine Primaquine and Artesunate. It was referred to hospital of Tropical Medicine. The laboratory reported P. knowlesi by PCR analysis. There was no malaria infection in all 96 persons. Both indoor and outdoor mosquitoes collections were found only Anopheles sawadwongporni, a non vector of P. knowlesi.
Conclusion: He traveled in the forest, where the monkeys live in Kangkoi and Muaklek Saraburi and Pakchong Nakonratchasima province, and he had a high behavior risk of mosquito bites. Thus, A P. knowlesi case may be infected from such jungle. Hence, we should strengthen surveillance and investigation of malaria for prevention and control effectively.