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[Clostridium bifermentans serovar malaysia, a new anaerobic bacterium pathogen to mosquito and blackfly larvae]

de Barjac H, Sebald M, Charles JF, Cheong WH, Lee HL

C. R. Acad. Sci. III, Sci. Vie, 1990;310(9):383-7.
PMID: 1972899

A strain of Clostridium bifermentans individualized as serovar malaysia (C.b.m.) according to its specific H antigen is toxic to mosquito and blackfly larvae when given orally. The toxicity occurs in sporulated cells which contain, in addition to spores, proteinic parasporal inclusion bodies and feather-like appendages; the amino acid content of the inclusion bodies is similar to that of Bacillus thuringiensis serovar israelensis (B.t.i.) and B. sphaericus crystals. The toxicity to Anopheles stephensi is as high as that of B.t.i. and the best strains of B. sphaericus. Culex pipiens is somewhat less susceptible, and Aedes aegypti much less. Pure parasporal inclusion bodies, isolated by ultracentrifugation on sucrose gradients, are highly toxic to mosquito larvae. The larvicidal power is destroyed by heating at 80 degrees C or by treatment with 50 mM NaOH. It is preserved by freeze-drying. The innocuity to mice of the sporulated cells is shown by different routes of administration: force-feeding, percutaneous, subcutaneous, intraperitoneal or intravenous injections. The potential for the biological control of mosquito and blackfly larvae is suggested.

Matched MeSH terms: Culicidae/microbiology*
Host range of Clostridium bifermentans serovar. malaysia, a mosquitocidal anaerobic bacterium

Thiery I, Hamon S, Gaven B, De Barjac H

J Am Mosq Control Assoc, 1992 Sep;8(3):272-7.
PMID: 1357087

Clostridium bifermentans serovar. malaysia (C.b.m.) is toxic to mosquito larvae. In this study, we quantified its toxicity to the mosquitoes, Aedes aegypti, Ae. albopictus, Ae. caspius, Ae. detritus, Anopheles stephensi, An. gambiae, Culex pipiens and Cx. quinquefasciatus. Anopheles larvae are the most susceptible, followed by Ae. detritus and Ae. caspius, then Culex and other Aedes larvae. According to mosquito species, the LC50 varies from 7 x 10(3) to 1.3 x 10(6) cells/ml. Three concentrations (10(7), 10(6) and 10(5) cells/ml) of C.b.m., Bacillus thuringiensis var. israelensis (B.t.i.) and Bacillus sphaericus were tested on Ae. aegypti, An. stephensi and Cx. pipiens larvae in order to determine the time necessary for each concentration to kill 50 and 90% of the population. Ninety percent of the 3 mosquito populations are killed within 4-15 h by the C.b.m. concentrations. Whatever the concentrations, C.b.m. kills at least 10 times less rapidly than B.t.i. but always quicker than B. sphaericus. Bioassays of C.b.m. bacterial cells or final whole culture were not toxic to Musca domestica and Drosophila melanogaster (Diptera) as well as to Phaedon cochleariae (Coleoptera) and Spodoptera littoralis (Lepidoptera).

Matched MeSH terms: Culicidae/microbiology*
Recent pathogen and mosquito host records from Penang Island, Malaysia

Chapman HC, Lacey LA, Yap HH

J Am Mosq Control Assoc, 1987 Jun;3(2):306-8.
PMID: 2904951
Matched MeSH terms: Culicidae/microbiology*
Arbovirus infections in Sarawak, October 1968--February 1970 Tembusu and Sindbis virus isolations from mosquitoes

Platt GS, Way HJ, Bowen ET, Simpson DI, Hill MN, Kamath S, et al.

Ann Trop Med Parasitol, 1975 Mar;69(1):65-71.
PMID: 235907

Thirty isolations of Tembusu virus and four of Sindbis virus were obtained from approximately 280 000 mosquitoes collected between October 1968 and February 1970 in Sarawak, particularly from K. Tijirak, a Land Dyak village 19 miles South of Kuching. Twenty-two isolations of Tembusu virus and two of Sindbis virus were from Culex tritaeniorhynchus; two of Tembusu virus and two of Sindbis virus came from Culex gelidus. Tembusu virus was active throughout the year at K. Tijirak, the highest infection rates in C. tritaeniorhynchus being in January-March and May-August, when the C. tritaeniorhynchus population was declining and ageing. These results confirm that C. tritaeniorhynchus is the principal arthopod host of Tembusu virus in Sarawak. Antibody studies suggest that birds, particularly domestic fowl, are probably vertebrate maintenance hosts of Tembusu and Sindbis viruses in Sarawak.

Matched MeSH terms: Culicidae/microbiology*
Aptamers isolated against mosquito-borne pathogens

Navien TN, Yeoh TS, Anna A, Tang TH, Citartan M

World J Microbiol Biotechnol, 2021 Jul 09;37(8):131.
PMID: 34240263 DOI: 10.1007/s11274-021-03097-0

Mosquito-borne diseases are a major threat to public health. The shortcomings of diagnostic tools, especially those that are antibody-based, have been blamed in part for the rising annual morbidity and mortality caused by these diseases. Antibodies harbor a number of disadvantages that can be clearly addressed by aptamers as the more promising molecular recognition elements. Aptamers are defined as single-stranded DNA or RNA oligonucleotides generated by SELEX that exhibit high binding affinity and specificity against a wide variety of target molecules based on their unique structural conformations. A number of aptamers were developed against mosquito-borne pathogens such as Dengue virus, Zika virus, Chikungunya virus, Plasmodium parasite, Francisella tularensis, Japanese encephalitis virus, Venezuelan equine encephalitis virus, Rift Valley fever virus and Yellow fever virus. Intrigued by these achievements, we carry out a comprehensive overview of the aptamers developed against these mosquito-borne infectious agents. Characteristics of the aptamers and their roles in diagnostic, therapeutic as well as other applications are emphasized.

Matched MeSH terms: Culicidae/microbiology
Mosquito fauna of the Bengkoka Peninsula, Sabah, Malaysia

Cheong WH, Loong KP, Mahadevan S, Mak JW, Kan SK

Southeast Asian J Trop Med Public Health, 1984 Mar;15(1):19-26.
PMID: 6146203

A total of 37 species of mosquitoes from seven genera were collected in six villages in the Bengkoka Peninsula, Sabah State, during two visits in 1981 in connection with studies on malaria and filariasis. Fifty-five per cent of the total mosquitoes collected were Mansonia. An. collessi constituted a new record of the species from Sabah. An. balabacensis was found to be naturally infected with sporozoites. Ma. bonneae was found to be naturally infected with Brugia, probably B. malayi. Parous rates of An. balabacensis and Ma. bonneae were very high with consequent high probability of survival ideally suiting transmission of malaria and filariasis.

Matched MeSH terms: Culicidae/microbiology*
Leptospirosis: Molecular trial path and immunopathogenesis correlated with dengue, malaria and mimetic hemorrhagic infections

Priya SP, Sakinah S, Sharmilah K, Hamat RA, Sekawi Z, Higuchi A, et al.

Acta Trop, 2017 Dec;176:206-223.
PMID: 28823908 DOI: 10.1016/j.actatropica.2017.08.007

Immuno-pathogenesis of leptospirosis can be recounted well by following its trail path from entry to exit, while inducing disastrous damages in various tissues of the host. Dysregulated, inappropriate and excessive immune responses are unanimously blamed in fatal leptospirosis. The inherent abilities of the pathogen and inabilities of the host were debated targeting the severity of the disease. Hemorrhagic manifestation through various mechanisms leading to a fatal end is observed when this disease is unattended. The similar vascular destructions and hemorrhage manifestations are noted in infections with different microbes in endemic areas. The simultaneous infection in a host with more than one pathogen or parasite is referred as the coinfection. Notably, common endemic infections such as leptospirosis, dengue, chikungunya, and malaria, harbor favorable environments to flourish in similar climates, which is aggregated with stagnated water and aggravated with the poor personal and environmental hygiene of the inhabitants. These factors aid the spread of pathogens and parasites to humans and potential vectors, eventually leading to outbreaks of public health relevance. Malaria, dengue and chikungunya need mosquitoes as vectors, in contrast with leptospirosis, which directly invades human, although the environmental bacterial load is maintained through other mammals, such as rodents. The more complicating issue is that infections by different pathogens exhibiting similar symptoms but require different treatment management. The current review explores different pathogens expressing specific surface proteins and their ability to bind with array of host proteins with or without immune response to enter into the host tissues and their ability to evade the host immune responses to invade and their affinity to certain tissues leading to the common squeal of hemorrhage. Furthermore, at the host level, the increased susceptibility and inability of the host to arrest the pathogens' and parasites' spread in different tissues, various cytokines accumulated to eradicate the microorganisms and their cellular interactions, the antibody dependent defense and the susceptibility of individual organs bringing the manifestation of the diseases were explored. Lastly, we provided a discussion on the immune trail path of pathogenesis from entry to exit to narrate the similarities and dissimilarities among various hemorrhagic fevers mentioned above, in order to outline future possibilities of prevention, diagnosis, and treatment of coinfections, with special reference to endemic areas.

Matched MeSH terms: Culicidae/microbiology
Fulltext Natural Wolbachia infection in field-collected Anopheles and other mosquito species from Malaysia

Wong ML, Liew JWK, Wong WK, Pramasivan S, Mohamed Hassan N, Wan Sulaiman WY, et al.

Parasit Vectors, 2020 Aug 12;13(1):414.
PMID: 32787974 DOI: 10.1186/s13071-020-04277-x

BACKGROUND: The endosymbiont bacterium Wolbachia is maternally inherited and naturally infects some filarial nematodes and a diverse range of arthropods, including mosquito vectors responsible for disease transmission in humans. Previously, it has been found infecting most mosquito species but absent in Anopheles and Aedes aegypti. However, recently these two mosquito species were found to be naturally infected with Wolbachia. We report here the extent of Wolbachia infections in field-collected mosquitoes from Malaysia based on PCR amplification of the Wolbachia wsp and 16S rRNA genes.
METHODS: The prevalence of Wolbachia in Culicinae mosquitoes was assessed via PCR with wsp primers. For some of the mosquitoes, in which the wsp primers failed to amplify a product, Wolbachia screening was performed using nested PCR targeting the 16S rRNA gene. Wolbachia sequences were aligned using Geneious 9.1.6 software, analyzed with BLAST, and the most similar sequences were downloaded. Phylogenetic analyses were carried out with MEGA 7.0 software. Graphs were drawn with GraphPad Prism 8.0 software.
RESULTS: A total of 217 adult mosquitoes representing 26 mosquito species were screened. Of these, infections with Wolbachia were detected in 4 and 15 mosquito species using wsp and 16S rRNA primers, respectively. To our knowledge, this is the first time Wolbachia was detected using 16S rRNA gene amplification, in some Anopheles species (some infected with Plasmodium), Culex sinensis, Culex vishnui, Culex pseudovishnui, Mansonia bonneae and Mansonia annulifera. Phylogenetic analysis based on wsp revealed Wolbachia from most of the mosquitoes belonged to Wolbachia Supergroup B. Based on 16S rRNA phylogenetic analysis, the Wolbachia strain from Anopheles mosquitoes were more closely related to Wolbachia infecting Anopheles from Africa than from Myanmar.
CONCLUSIONS: Wolbachia was found infecting Anopheles and other important disease vectors such as Mansonia. Since Wolbachia can affect its host by reducing the life span and provide resistance to pathogen infection, several studies have suggested it as a potential innovative tool for vector/vector-borne disease control. Therefore, it is important to carry out further studies on natural Wolbachia infection in vector mosquitoes' populations as well as their long-term effects in new hosts and pathogen suppression.

Matched MeSH terms: Culicidae/microbiology*
Dengue hemorrhagic fever in Malaysia: the 1973 epidemic

Wallace HG, Lim TW, Rudnick A, Knudsen AB, Cheong WH, Chew V

Southeast Asian J Trop Med Public Health, 1980 Mar;11(1):1-13.
PMID: 6105712

The first major Malaysian epidemic of dengue hemorrhagic fever with severe manifestations occurred in 1973, with 969 reported cases and 54 deaths. In a detailed study of 138 clinically diagnosed and laboratory confirmed cases at the General Hospital in Kuala Lumpur, hemorrhagic manifestations were observed in 68.7% and shock in 18.1% of the patients. The cases occurred mainly from May to September, largely in urban and suburban areas of the majority of the states in the country. A main focus of infection was Jinjang, a heavily populated outlying district of Kuala Lumpur, where unusually high incidences of morbidity, severe disease and mortality were seen. Severe disease was seen mostly in children under the age of 15 years, although a significant number of adults suffered milder illnesses. The Chinese population was chiefly affected, due to their living in crowded, low-income housing where the vector, Aedes aegypti, occurred in the greatest numbers. All four dengue types were recovered during the epidemic period, although dengue 3 (DEN-3) was incriminated as the major epidemic type. Entomological data revealed high indices of A. aegypti throughout the country and left little doubt that this epidemic was aegypti transmitted. Spraying and fogging operations were carried out in attempts to control vector populations.

Matched MeSH terms: Culicidae/microbiology
Alphaviruses in Peninusular Malaysia: I. Virus isolations and animal serology

Marchette NJ, Rudnick A, Garcia R, MacVean DW

Southeast Asian J Trop Med Public Health, 1978 Sep;9(3):317-29.
PMID: 34888

A survey of the activity of three alphaviruses (Sindbis, getah and chikungunya) in Peninsular Malaysia was conducted between 1962 and 1970. Serum samples were examined from 3,917 vertebrates representing a wide variety of wild and domestic animals throughout the peninsula for hemagglutination-inhibiting and neutralizing antibodies. A total of 548,939 mosquitoes were collected from different habitats, including jungle, rural, suburban and urban areas, and the majority of the females taken were examined for the presence of virus. Two strains of Sindbis virus and one strain of getah virus were isolated from pools of Culex mosquitoes collected in and around domestic animal shelters. Analysis of the serological results indicated that, 1) getah virus is associated principally with large domestic animals, particularly swine, 2) Sindbis virus is associated with large domestic animals and birds, especially domestic ducks, and 3) chikungunya virus, which has not yet been isolated in Malaysia, appeared to be present at a very low level of activity, probably with wild monkeys as the vertebrate hosts.

Matched MeSH terms: Culicidae/microbiology
Arbovirus infections in Sarawak, October 1968--February 1970: Japanese encephalitis virus isolations from mosquitoes

Simpson DI, Bowen ET, Way HJ, Platt GS, Hill MN, Kamath S, et al.

Ann Trop Med Parasitol, 1974 Dec;68(4):393-404.
PMID: 4155608
Matched MeSH terms: Culicidae/microbiology*