Very high carriage of gametocytes in asymptomatic low-density Plasmodium falciparum and P. vivax infections in western Thailand.

BACKGROUND: Low-density asymptomatic infections of Plasmodium spp. are common in low endemicity areas worldwide, but outside Africa, their contribution to malaria transmission is poorly understood. Community-based studies with highly sensitive molecular diagnostics are needed to quantify the asymptomatic reservoir of Plasmodium falciparum and P. vivax infections in Thai communities. METHODS: A cross-sectional survey of 4309 participants was conducted in three endemic areas in Kanchanaburi and Ratchaburi provinces of Thailand in 2012. The presence of P. falciparum and P. vivax parasites was determined using 18S rRNA qPCR. Gametocytes were also detected by pfs25 / pvs25 qRT-PCRs. RESULTS: A total of 133 individuals were found infected with P. vivax (3.09%), 37 with P. falciparum (0.86%), and 11 with mixed P. vivax/ P. falciparum (0.26%). The clear majority of both P. vivax (91.7%) and P. falciparum (89.8%) infections were not accompanied by any febrile symptoms. Infections with either species were most common in adolescent and adult males. Recent travel to Myanmar was highly associated with P. falciparum (OR = 9.0, P = 0.001) but not P. vivax infections (P = 0.13). A large number of P. vivax (71.5%) and P. falciparum (72.0%) infections were gametocyte positive by pvs25/pfs25 qRT-PCR. Detection of gametocyte-specific pvs25 and pfs25 transcripts was strongly dependent on parasite density. pvs25 transcript numbers, a measure of gametocyte density, were also highly correlated with parasite density (r 2 = 0.82, P < 0.001). CONCLUSIONS: Asymptomatic infections with Plasmodium spp. were common in western Thai communities in 2012. The high prevalence of gametocytes indicates that these infections may contribute substantially to the maintenance of local malaria transmission.

Long-term impact of childhood malaria infection on school performance among school children in a malaria endemic area along the Thai-Myanmar border.

BACKGROUND: Children represent a high-risk group for malaria worldwide. Among people in Thailand who have malaria during childhood, some may have multiple malaria attacks during their lifetime. Malaria may affect neurological cognition in children, resulting in short-term impairment of memory and language functions. However, little is known regarding the long-term effects of malaria infection on cognitive function. This study examines the long-term impact of malaria infection on school performance among school children living in a malaria-endemic area along the Thai-Myanmar border. METHODS: A retrospective cohort study was conducted among school children aged 6-17 years in a primary-secondary school of a sub-district of Ratchaburi Province, Thailand. History of childhood malaria infection was obtained from the medical records of the sole malaria clinic in the area. School performance was assessed by using scores for the subjects Thai Language and Mathematics in 2014. Other variables, such as demographic characteristics, perinatal history, nutritional status, and emotional intelligence, were also documented. RESULTS: A total of 457 students were included, 135 (30 %) of whom had a history of uncomplicated malaria infection. About half of the malaria-infected children had suffered infection before the age of four years. The mean scores for both Mathematics and Thai Language decreased in relation to the increasing number of malaria attacks. Most students had their last malaria episode more than two years previously. The mean scores were not associated with duration since the last malaria attack. The association between malaria infection and school performance was not significant after adjusting for potential confounders, including gender, school absenteeism over a semester term, and emotional intelligence. CONCLUSIONS: This study characterizes the long-term consequences of uncomplicated malaria disease during childhood. School performance was not associated with a history of malaria infection, considering that most students had their last malaria infection more than two years previously. These findings indicate that the impact of uncomplicated malaria infection on school performance may not be prolonged.

Knowledge, attitudes and practices (kap) regarding influenza A (H1N1) among a population living along Thai-Myanmar border, Ratchaburi Province, Thailand.

The 2009 influenza A (H1N1) outbreaks in Thailand was successfully controlled, partly through the use of electronic media to educate the public. People living along the Thai-Myanmar border may have less access to this electronic media or might have health beliefs that differ from the general Thai population with potential to impact an influenza outbreak. We conducted a survey to assess the knowledge, attitudes and practices regarding influenza among people living along the Thai-Myanmar boder in Ratchaburi Province, Thailand. Of 110 house- holds surveyed, 96% were Karen ethnicity. Greater than 50% were uneducated and most had a low family income. Knowledge about influenza was low. Attitudes regarding infection were mostly negative among the elderly in this area. Practices regarding influenza were moderately good. Education level was associated with knowledge and practice. Income level and wealth indicators were associated with knowledge and having a radio or TV was associated with good practices. Preventive behavior was associated with good knowledge but not with attitudes about influenza. Health education campaigns are needed in these communities to help people adopt desired changes in behavior to improve personal hygiene.

Chikungunya virus was isolated in Thailand, 2010.

Chikungunya fever (CHIKF) is an acute febrile illness caused by a mosquito-borne alphavirus, chikungunya virus (CHIKV). This disease re-emerged in Kenya in 2004, and spread to the countries in and around the Indian Ocean. The re-emerging epidemics rapidly spread to regions like India and Southeast Asia, and it was subsequently identified in Europe in 2007, probably as a result of importation of chikungunya cases. On the one hand, chikungunya is one of the neglected diseases and has only attracted strong attention during large outbreaks. In 2008-2009, there was a major outbreak of chikungunya fever in Thailand, resulting in the highest number of infections in any country in the region. However, no update of CHIKV circulating in Thailand has been published since 2009. In this study, we examined the viral growth kinetics and sequences of the structural genes derived from CHIKV clinical isolates obtained from the serum specimens of CHIKF-suspected patients in Central Thailand in 2010. We identified the CHIKV harboring two mutations E1-A226V and E2-I211T, indicating that the East, Central, and South African lineage of CHIKV was continuously circulating as an indigenous population in Thailand.

Directly observed therapy with primaquine to reduce the recurrence rate of plasmodium vivax infection along the Thai-Myanmar border.

This study was carried out from April 2005 to June 2006 to evaluate the recurrence of P. vivax malaria infection in relation to drug compliance along the Thai-Myanmar border in Ratchaburi, Thailand. Ninety-two patients with vivax malaria were sequentially assigned to 2 groups. Both groups received a standard dose of chloroquine (total dose = 2.5 g) for 3 days and primaquine (total dose = 210 mg) for 14 days. The experimental group received a full course of treatment using daily directly observed therapy (DOT) while subjects in the control group were given the medication with necessary instructions to take as self-administered therapy (SAT). Patients were followed up for 3 months on Days 14, 21, 28, 60 and 90. Five of 46 patients from the SAT group had recurrence of malaria on Days 21, 44, 60, 72 and 87. Recurrence was not observed among patients in the DOT group. Survival analysis also showed significant differences between the SAT and DOT groups (p <0.05). The study suggests patient compliance with the 14-day primaquine treatment with DOT improve the outcome of .vivax malaria treatment.