The Impact of Preventive Fogging on Entomological Parameters in a University Campus in Malaysia

Introduction: Preventive fogging is defined as space spraying of insecticide against mosquitoes in order to prevent outbreak of mosquito borne infection. Despite provision of various preventive and control activities against dengue and chikungunya infection by Ministry of Health Guideline, the detail on preventive fogging has not yet specified. However, this has been adopted by certain institutions as part of the routine strategies against dengue outbreak. A study on preventive fogging was conducted in one of the hostels in Universiti Putra Malaysia. The research was done for 16 weeks in which one routine fogging activity was done at the mid period of study. The main objectives of this study were to determine the effectiveness of preventive fogging activities against Aedes mosquitoes and to identify the distribution and abundance of Aedes mosquitoes in the area. Method: The fogging activity was carried out by the management staff as part of their preventive measures in the student hostels. Ovitrap was used as an indicator to monitor the impact of fogging activity and its continuous surveillance was monitored weekly. The ovitraps were placed indoors and outdoors. Species identification was carried out in the laboratory. The SPSS program was used to analyse the statistical data on the effectiveness of fogging activity. Larval count (indoors and outdoors) and ovitrap index (OI) readings were identified as ovitrap surveillance data for statistical analysis. Results: The results showed that Aedes albopictus was the only species of the genus Aedes found in this hostel. The area had been highly infested by Ae. Albopictus as indicated by high Ovitrap Index ranging between 48.33% to 90.00%. The mean (SD) of Ovitrap Index was reduced from 71.67% (12.73%) (before the preventive fogging), to 69.42% (14.40%) (after the fogging). Overall reduction in mosquito and larval density was also observed between pre and post fogging activity in this study. Conclusion: The implementation of preventive fogging has favourably reduced the dengue vector population up to 5 weeks after the introduction of preventive fogging. However, sole dependency on preventive fogging may lead to insecticide resistance. Revisiting the policy on preventive fogging; and identifying it as an additional tool for preventing dengue infection in higher learning institutions are recommended.

Plant-Derived Antimalarial Agents: From Crude Extracts To Isolated Bioactive Compounds

Despite decades of intense research, malaria remains a deadly disease of the developing worlds. Drugresistance to limited available antimalarials, in part, has contributed to the persistence of this infectious disease. Likewise, the use of antimalarials such as artemisinin, though effective in global malaria control programs, is hampered by high cost and limited supply. Therefore, identification of an antimalarial drug that is easy to isolate and produce, inexpensive, and demonstrates little toxicity across a diverse population represents the ideal agent needed for global malaria control programs and eradication of this deadly disease. This review discusses several antimalarial compounds containing unique structural composition that have been isolated and characterized from plant sources. These compounds have exhibited promising antimalarial activities in vitro and in vivo. However, limitations such as toxicity, low bioavailability and/or poor solubility have probably restricted the scope of use for several plant products in humans. Nevertheless, plants provide novel leads, which can be developed into safe drugs by synthetic strategies as exemplified by artemether and quinoline class of antimalarials. Therefore, plant bioactive compounds described herein provide useful alternatives, which could be modulated to obtain antimalarials active against not only drug-sensitive, but also drug-resistant and multi-drug resistant strains of Plasmodium. In this direction, semi synthetic approaches to newer and modified antimalarials have provided useful insights into their applicability in antimalarial drug discovery.

Intestinal microsporidiosis: A new entity in Malaysia?

Intestinal microsporidia is an emerging human disease caused by microsporidia. A study was conducted to determine the prevalence of microsporidia in patients with gastro-intestinal symptoms and to examine the clinical manifestations associated with intestinal microsporidiosis. A descriptive cross-sectional study using a well-structured questionnaire; a review of medical records was also undertaken. Positive stool samples were defined as presence of one or more pinkish-violet ovoid structures with a belt-like stripe under high power field (100x) using modified gram-chromotrope stain (MGC). A total of 353 faecal specimens of patients was examined and 100 patients were found to have positive stool samples for microsporidia. The overall prevalence of microsporidia was 28.3%. Acute and chronic diarrhoea were seen in 49.0% and 36.0% patients, respectively. The commonest clinical presentations were diarrhoea (85.0%) with 83.0% of patients having loose or watery stools, vomiting (75.0%), foul-smelling stools (60.0%), nausea (59.0%) and cramping abdominal pain (39.0%). The least common symptoms were fever (15.0%), mucous in stool (5.0%) and blood in stool (4.0%). This study concludes that the prevalence of microsporidia is still high (28.3%) and the majority of patients (93.0%) are symptomatic; the most common gastro-intestinal symptom is diarrhoea with loose or watery stools. Hence, it is recommended that a stool screening for microsporidia be done in selected patients presented with gastrointestinal symptoms.

A recombinant 19 kDa Plasmodium berghei merozoite surface protein 1 formulated with alum induces protective immune response in mice

We investigated the immunogenicity of recombinant rMSP1 (rPbMSP1) that was generated from Plasmodium berghei. The rPbMSP1 formulated in alum was found to be immunogenic which induced high levels of specific anti-rPbMSP1 antibody. The IgG2a response predominated over IgG1 during the challenge infection in the vaccinated mice. Mice vaccinated with rPbMSP1 in alum mounted significant protective immunity against challenge infection (P < 0.01). On day 121 after the booster, three out of ten mice immunized with rPbMSP1 in PBS survived parasite infection (P < 0.05) and eight out of ten mice vaccinated with r MSP1 in alum did (P < 0.01). Hence, immunization with MSP1 in alum obviously has conferred protective effects, which prevented death from P. berghei lethal infection in mice (P < 0.01). These observations provide an excellent model for clinical assessment of this formulation in human subjects.