Natefa Rukmanee. Reappearance pattern of Plasmodium vivax malaria in the community near Thai-Myanmar Border, Ratchaburi province . Master's Degree(Tropical Medicine). Mahidol University. : Mahidol University, 2006.
Reappearance pattern of Plasmodium vivax malaria in the community near Thai-Myanmar Border, Ratchaburi province
Abstract:
Malaria is one of the most severe public health problems worldwide; it is responsible for over 300-500 million cases and is serious in developing countries. Many malaria infections do not show classic pattern of recurrent fever at all. According to the dormant stage of the hypnozoite form, relapses occur in Plasmodium vivax infections and it is difficult to predict when they will occur.
The study was conducted at Rajanagarindra Tropical Disease International Center (RTIC) under the supervision of personnel from the Faculty of Tropical Medicine, Mahidol University. This study found reappearance patterns, to identify the times and associated factors for the reappearance of P. vivax cases on the Thai-Myanmar border.
In a six-year retrospective cohort from 1998-2003, the assumed risk free period in rates within 60 and 90 days were 0.34 and 0.35 episodes per person-year respectively.
The cohort of 647 slide-positive P. vivax cases was separated into to 2 groups. The reappearance cases for criteria-positive slides ≤ 60 days was 87 persons, while the other group ≤ 90 days was 130 persons. The maximum for reappearance in the 60-day group was 5 times, and in the 90-day group 6 times. The median days for the reappearance in the 60-day group was 42 days and for the 90 day-group 55 days. The reappearance pattern showed fluctuation but these peaks were at days 43, 60 and 65, 68 for the 60- and 90-day groups, respectively. In reappearance at 60 days was highest in July and lowest in January; reappearance at 90 days was highest in July, August and October and lowest in January and February. Risk of reappearance for the 60- and 90-day groups was 13.45 % and 20.09 % respectively. The rate of reappearance per 100 episodes in the 60- and 90-day groups was 9.70 and 15.71 episodes, respectively.
In conclusion, the follow-up time was 60 days, because the median of reappearance not greater than 60 days. The factor associated with reappearance was age, suggesting drug compliance was related to age < 8 years.