Modeling factors influencing malaria incidence in Myanmar.

This is a documentary study to determine factors influencing malaria incidence in Myanmar. The period of study covered was from 1989 to 1998 using time series data. Multiple regression analysis was performed on the dependent variable, yearly incidence of malaria in Myanmar, with hypothesized independent variables including variables related to epidemiology, demography, service and socioeconomic status. Malaria incidence was inversely associated with the government budget for malaria control at the 5% level and with the case fatality rate of malaria at the 10% level. Other variables: yearly gross domestic product, yearly proportion of Plasmodium falciparum cases and yearly DDT use of spraying displayed expected signs but were not statistically significant.

Ex post and ex ante willingness to pay (WTP) for the ICT Malaria Pf/Pv test kit in Myanmar.

Willingness to pay (WTP) for the ICT Malaria Pf/Pv test kit was assessed by the contingent valuation method using a bidding game approach in two villages in Myanmar. Kankone (KK) village has a rural health center (RHC) and Yae-Aye-Sann (YAS) is serviced by community health worker (CHW). The objectives were to assess WTP for the ICT Malaria Pf/Pv test kit and to determine factors affecting the WTP. In both villages WTP was assessed in two different conditions, ex post and ex ante. The ex post WTP was assessed at an RHC in the KK village and at the residence of a CHW in the YAS village on patients immediately following diagnosis of malaria. The ex ante WTP was assessed by household interviews in both villages on people with a prior history of malaria. Ordinary least squares (OLS) multiple regression analysis was used to analyze factors affecting WTP. The WTP was higher in ex post conditions than ex ante in both villages. WTP was significantly positively associated with the average monthly income of the respondents and severity of illness in both ex post and ex ante conditions (p < 0.001). Distance between the residence of the respondents and the health center was significantly positively associated (p < 0.05) in the ex ante condition in a household survey of YAS village. Traveling time to RHC had a negative relationship with WTP (p < 0.05) in the ex post condition in the RHC survey in KK village.

Fast liver alkaline phosphatase isoenzyme in diagnosis of malignant biliary obstruction.

Fast liver alkaline phosphatase isoenzyme was measured by cellulose acetate electrophoresis in the sera obtained from 84 patients with specific hepatobiliary diseases and 10 control subjects. The mean value of this isoenzyme in patients with malignant extrahepatic obstruction was 130.58 +/- 107.08 U/L, significantly higher than that of patients with benign extrahepatic obstruction (65.63 +/- 34.14 U/L), as well as patients with intrahepatic cholestasis and infiltrative liver cancers (65.31 +/- 38.11 U/L and 48.47 +/- 36.85 U/L, respectively). Furthermore, we could not detect this isoenzyme in normal individuals. When 100 U/L was used as a cut-off value to discriminate between patients with malignant extrahepatic obstruction and the remaining hepatobiliary disorders, the sensitivity, specificity and accuracy of the test were 63 per cent, 84 per cent and 80 per cent, respectively. It is concluded that the fast liver isoenzyme could be a useful marker in diagnosis of malignant extrahepatic obstruction.

Alpha-L-fucosidase as a serum marker of hepatocellular carcinoma in Thailand.

To evaluate the role of serum alpha-L-fucosidase (AFU) in the diagnosis of hepatocellular carcinoma (HCC), we simultaneously studied both AFU activity and alpha-fetoprotein (AFP) level in 60 patients with HCC, 60 patients with cirrhosis and chronic hepatitis each, 30 patients with other liver tumors and 60 healthy subjects. Serum AFU activity in patients with HCC (1,418.62 +/- 575.76 nmol/ml/hr) was significantly higher than that found in cirrhosis (831.25 +/- 261.13 nmol/ml/hr), chronic hepatitis (717.71 +/- 205.86 nmol/ ml/hr) or other tumors (706.68 +/- 197.67 nmol/ml/hr) and in controls (504.18 +/- 121.88 nmol/ml/hr, p < 0.05). With 870 nmol/ml/hr (mean value of controls plus 3 standard deviations) considered as the cut-off point, AFU was more sensitive (81.7 vs 39.1%) but less specific (70.7 vs 99.3%) than AFP at a level of > 400 ng/ml as a tumor marker of HCC. With both markers combined, the sensitivity was improved to as much as 82.6%. AFU activity in HCC patients was correlated to tumor size (r = 0.3529, p = 0.006) but not associated with tumor staging classified by Okuda's criteria (p = 0.1). The AFU activity in the viral hepatitis group (hepatitis B or C) was also significantly higher than in the non-viral group (p = 0.0005). We conclude AFU to be a useful marker, in conjunction with AFP and ultrasonography, for detecting HCC, particularly in patients with underlying viral hepatitis and cirrhosis.

Epidemiological studies of malaria at Pong Nam Ron, eastern Thailand.

Malaria is still a serious health problem in Thailand. Present attempts at controlling the disease by drug treatment and other means remain unsatisfactory. Thus, development of vaccination against malaria is a major research goal of malaria immunology. The objective of this study was to acquire epidemiological base line data for subsequent vaccine trials. A cross-sectional descriptive survey was conducted among 451 local inhabitants during the beginning of the transmission season in June 1989 at Pong Nam Ron District, Chanthaburi Province, Eastern Thailand where malaria transmission was likely to be high. Following the cross-sectional survey weekly morbidity surveillance was started to detect new cases of malaria by using active and passive case detection at the district hospital, local health centers and at neighboring malaria clinics. Entomological observations were made monthly to determine inoculation rates. Forty-six percent of the population were male and 54% female; one third were under the age of 15 and 14% under the age of 5 years. Eighty percent of the adults were married. Sixty percent of the subjects interviewed gave a history of malarial illness in the past. Malaria, malnutrition, abnormal hemoglobin diseases and parasitic infestation were the main health problems in the study area. The annual parasite incidence of malaria was 149.6/1,000 population and two-thirds of them were asymptomatic indicating a semi-immune condition among these subjects. It was difficult to interpret the results of entomological studies due to low density of the malaria vector.

A longitudinal study of seroreactivities to a major blood stage antigen (Pf155/RESA) of the malaria parasite Plasmodium falciparum in an endemic area of Thailand.

We have performed a longitudinal study of the formation of antibodies to Plasmodium falciparum in an area of Thailand where malaria transmission is moderate and seasonal. The study population comprised 118 subjects living in two villages 230 km southeast of Bangkok. All subjects included in this study were seropositive for antibodies to the blood stages of P. falciparum but only approximately 80% had antibodies to the blood stage antigen Pf155/RESA when assayed by erythrocyte membrane immunofluorescence (EMIF) or peptide ELISA during the period of maximal transmission. The reduced capacity to form these antibodies in a significant fraction of subjects living under comparable environmental and socio-economic conditions may reflect a genetic but antigen specific non-responsiveness. Both seropositivity and mean antibody titers to Pf155/RESA and its B-cell epitopes tended to be slightly higher during the rainy than during the dry season but the seasonal variations were slight and statistically not significant. Parasite rates were significantly higher in the rainy than in the dry season in both the EMIF positive and the EMIF negative groups. However, during the rainy season, the parasite rates in subjects with no or low titered antibodies to Pf155/RESA were significantly higher than those in subjects having such antibodies. The results suggest that antibodies to Pf155/RESA and some of its defined epitopes may be of importance for controlling parasitemias.

Malaria in a rural area of eastern Thailand: baseline epidemiological studies at Bo Thong.

Malaria is still a serious health problem in Thailand. Present attempts at controlling the disease by drug treatment and other means remain unsatisfactory. Thus, development of vaccination against malaria is a major research goal of malaria immunology. The objective of this study was to acquire epidemiological base line data for subsequent vaccine trials. A cross-sectional descriptive survey was conducted among 253 local inhabitants during the beginning of the transmission season in July 1989 at Bo Thong District, Chonburi Province, Eastern Thailand where malaria transmission was likely to be moderately high. Following the cross-sectional survey weekly morbidity surveillance was started to detect new cases of malaria by using active and passive case detection at the district hospital, local health centers and at neighboring malaria clinics. Fifty-four percent of the population were male and forty-six percent female: nearly a half (48.3%) were under the age of 15 and 17% under the age of 5 years. Eighty percent of the adults were married. Seventy percent of the subjects interviewed gave a history of malarial illness in the past. Malaria, malnutrition, anemia abnormal hemoglobin diseases and parasitic infestations were the main health problems in the study area. The annual parasite incidence of malaria was 169.4/1,000 population and 77% of parasitemic individuals were asymptomatic, indicating the existence of a semi-immune condition among these subjects. Antibody level to crude parasite antigen increased with age. It is hoped that the information obtained from these field studies may be useful in malaria vaccine trials in the near future.