In 2011, we reported occurrence of natural human infections with Brugia pahangi, a filarial worm of dogs and cats, in a surburb of Kuala Lumpur, the capital city of Malaysia. Our preliminary entomological survey at that time suggested the mosquito species Armigeres subalbatus as the vector of the zoonotic infections. In this present report, we provide biological evidence to confirm our preliminary finding.
A study was carried out to identify some of the cultural factors in the epidemiology of filariasis in an endemic community in Malaysia. The viewpoint of the community, data an responses on knowledge of illness and filariasis, host related factors, health examination, vector study were analysed and discussed. The observations noted on cultural factors were: Occupational pattern: Different agricultural occupations seemed to related to transmission in terms of body exposure. Activities not related to production of crops: Play groups in late afternoon, bathing of household members near and after sunset, congregations at prayer houses very much exposed the population to mosquito bites in different degree in terms of length of time spent outside the house. Knowledge of filariasis: Filariasis was understood in terms of elephantiasis, the chronic stage of the disease. Other signs of disease-adenolymphangitis, red lines running down one or both legs and abscess were generally recognized but not often annonated with specific disease. Attitude toward disease: Filariasis was not seen as a health problem and the idea of filarial worms was still hard to believe. Knowledge on disease causation: Biological causes were generally recognized, though the idea of bacteria was not widespread.
A study to identify the knowledge of infected and uninfected respondents on filariasis and epidemiologic factors in one endemic community in Malaysia to determine their role in the transmission and control of filariasis was carried out. The data were collected by non-participant observations and interviews using semi-structured schedules. The majority of respondents in both groups had knowledge of filariasis. There was no marked difference between male and female respondents, and similarly, there was fair distributions of knowledgeable respondents with and without some years of schooling. On filarial transmission, 9.2% of the infected said that filariasis was contacted through mosquito bites, while among the uninfected it was 7.4%. Within the infected, 14.8% thought that filarial worms entered the human body through the consumption of unhygenically prepared foods and drinks while, among the uninfected it was 20.4%. Both groups were aware of the presence of mosquitoes in their village. However, the majority did not associate this factor with host's susceptibility to filarial infections. Rather, they were of the opinion that personal hygiene and proper meals had something to do with filariasis. The findings showed there was general awareness of filariasis in the community which might indicate that the health campaigns had reached various levels of the population. Yet, they still lacked knowledge on disease transmission. Also, they did not make direct association between environment and exposure to mosquitoes bites though they were aware of their presence but which they regarded as not directly harmful to their health.
Filarial infections in 447 cats and 68 dogs from six endemic areas of human filariasis in Peninsular Malaysia were studied as part of the study on the zoonotic transmission of subperiodic Brugia malayi infection. 20.6% of cats and 57.4% of dogs had filarial infections. Cats were infected with subperiodic B. malayi, B. pahangi, Dirofilaria repens and D. immitis. Dogs were infected with B. pahangi and D. immitis. 6.9% of the cats had subperiodic B. malayi infection. The zoonotic implications of these infections and their impact on the filariasis control programme in Peninsular Malaysia were discussed.
We conducted a field study of a rapid test (Brugia Rapid) for detection of Brugia malayi infection to validate its sensitivity and specificity under operational conditions. Seven districts in the state of Sarawak, Malaysia, which are endemic for brugian filariasis, were used to determine the test sensitivity. Determination of specificity was performed in another state in Malaysia (Bachok, Kelantan) which is non-endemic for filariasis but endemic for soil-transmitted helminths. In Sarawak both the rapid test and thick blood smear preparation were performed in the field. The rapid test was interpreted on site, whereas blood smears were taken to the district health centres for staining and microscopic examination. Sensitivity of Brugia Rapid dipstick as compared with microscopy of thick blood smears was 87% (20/23; 95% CI: 66.4-97.2) whereas the specificity was 100% (512/512). The lower sensitivity of the test in the field than in laboratory evaluations (> or =95%), was probably due to the small number of microfilaraemic individuals, in addition to difficulties in performing the test in remote villages by field personnel. The overall prevalence of brugian filariasis as determined by the dipstick is 9.4% (95% CI: 8.2-0.5) while that determined by microscopy is 0.90% (95% CI: 0.5-1.3) thus the dipstick detected about 10 times more cases than microscopy. Equal percentages of adults and children were found to be positive by the dipstick whereas microscopy showed that the number of infected children was seven times less than infected adults. The rapid dipstick test was useful as a diagnostic tool for mapping and certification phases of the lymphatic filariasis elimination programme in B. malayi-endemic areas.
Studies on the social and behavioral aspects of filariasis transmission were conducted in the transmigration area of Kumpeh, in the province of Jambi, Sumatra, Indonesia. Three methods were used in the study namely, interview, participation observation and focus group discussion. A total of 266 respondents (136 males and 130 females) were interviewed. The results of the study showed the most of the transmigrants were not familiar with the word "filariasis". They were more used to the name of "penyakit kaki gajah" or "elephant's leg" disease or "untut". The word "untut" is similar to what people of Selangor, Malaysia call this disease. The community attitude towards control efforts against filariasis was positive, as evidenced by their readiness in being bled and their readiness to help change the environment which serves as mosquito breeding places. Usually the transmigrants live in the "ladang" or dry farming area for 3-4 months to protect their crops from damages by pests. This habit was rather negative, because in their "ladangs" they exposed themselves to high risk of mosquito bites and thus to filariasis infection.
A total of 1,134 finger-pricked blood samples were collected from residents of Setiu, Terengganu. A drop of blood was used to make thick blood smear and about four drops were used for obtaining serum. The smears were stained and examined by the State Vector Control Unit in Kuala Terengganu, while the serum samples were tested for specific IgG4 antibodies to a novel recombinant antigen using Brugia-Elisa. Prevalence of filariasis in these areas were found to be 0.26% (3/1,134) using thick blood smear examination and 2.47% (28/1,134) using Brugia-Elisa, thus demonstrating the greater sensitivity of the latter test. In addtion, Brugia-Elisa showed a high level of specificity (97.8%, 1,106/1,131) when compared to thick blood smear examination.
R. sabanus and R. muelleri are very common in the lowland forests of Malaysia. In nature they are infected with Breinlia sp. and D. ramachandrani. In an attempt to determine whether they are also susceptible to subperiodic B. malayi and thereby being potential reservoirs of infection of the disease, 24 R. muelleri and 17 R. sabanus were experimentally infected with the parasite. Results show that although they can support the full development of the parasite, they are poor hosts. This confirms the observation that in Malaysia natural infection of Rattus spp. with the parasite has not been seen. These rats therefore are probably not important in the zoonotic transmission of subperiodic B. malayi in Malaysia.