Knowledge on lymphatic filariasis and the response to July 2002 mass treatment campaign in two communities in the Galle district.

OBJECTIVE: To ascertain the knowledge on filariasis and response to the July 2002 mass treatment campaign in two sample populations. DESIGN: Application of pre-tested questionnaire by direct interviews of individuals from randomly selected streets. METHODS: Study areas were a coastal community in Unawatuna (population sample 381), and an inland community in Baddegama (population sample 236) in the Galle district. They were interviewed twice, 4 weeks before the mass drug administration (MDA) and 4 to 7 days after. RESULTS: The sample population of Unawatuna had a greater awareness of the clinical and parasitological features of the disease (p = 0.0003) and the drug treatment (p = 0.00380 than that of Baddegama. Only 5.5% of the combined sample attributed the cause of filariasis to a parasitic worm. However, over 70.0% of them knew that transmission was through mosquito bites. Volunteers formed 87.5% of the work force used for drug distribution in Unawatuna and 70.1% in Baddegama. The balance work force were Grama Niladaris and Public Health Midwives. Drugs were received by 76.9% of the Unawatuna sample compared with 89.0% at Baddegama (p < 0.001). Among those who received the drugs, consumption was 91.8% in Unawatuna and 96.2% in Baddegama. Taking the two communities together adverse effects were experienced by 22.9%. These effects in night time drug consumers (10.4%) were significantly less than in day time consumers (19.8%) (p < 0.005). The adverse effects were sleepiness (37.8%), malaise (28.2%), headache (16.8%), vomiting (5.1%), nausea (4.5%) and fever (3.9%). The message of mass treatment was carried to the community by the people themselves on the eve and on the day of drug distribution. Over 95% agreed that in future programs drugs should be delivered to their homes.

Efficacy of a single dose treatment of Wuchereria bancrofti microfilaria carriers with diethylcarbamazine in Matara, Sri Lanka.

OBJECTIVE: To test the efficacy of diethylcarbamazine DEC single dose regimen of 6 mg/kg body weight (bw) on a sample of Wuchereria bancrofti microfilaria (mf) carriers in Matara. DESIGN: 6 mg/kg bw DEC dose in 50 mg tablets given under direct observation to the subjects at 23.00 hours after pre-treatment blood collection for mf counts. Post-treatment mf counts were at 1, 2 weeks and 1, 3, 6, 12 months. SUBJECTS: 31 asymptomatic mf carriers, 14 males, age range 6 to 62 years. RESULTS: Treatment resulted in 89 to 97% success rate, 19 to 28% cure rates and 74 to 80% reduction in mf density. There was no difference statistically in the success rate and cure rate at 6 and 12 months. The effect of DEC treatment at 6 and 12 months compared by sex, age group and pre-treatment mf level showed no difference. 64.5% of the carriers treated had at least one mild adverse reaction. Rates of the common reactions were 41.9% fever, 22.6% headache and 16.1% joint pains. CONCLUSION: A new mass treatment program has been initiated by the national Antifilariasis Campaign using the single dose DEC 6 mg/kg bw regimen. The satisfactory reduction in mf density at 6 and 12 months following DEC single dose treatment we observed provides support for this program.

Microfilarial periodicity of Wuchereria bancrofti and man landing periodicity of the vector Culex quinquefasciatus say in Matara, Sri Lanka.

OBJECTIVE: To compare the microfilarial periodicity of Wuchereria bancrofti, with the man landing periodicity of the vector Culex quinquefasciatus in Matara, Sri Lanka. DESIGN: Periodicity was estimated using a statistical method. 60 microliters finger prick (FP) blood was smeared from a single subject every 2 hours for 24 hours of the day to make 12 samples. Smears were stained with Giemsa and the microfilariae (mff) counted. Man landing catches of mosquitoes were made inside a bedroom of a house in the same area on a sleeping volunteer during the night, between 18.00 and 06.00 hours. Each hourly catch was placed in separate paper cups. Hourly C. quinquefasciatus taken were counted. SUBJECTS: 10 asymptomatic microfilaria (mf) carriers. RESULTS: The individual mf peaks in the 10 carriers varied from 22.00 to 04.00 hours. Using the statistical method the parameter k showing the mf peak hour was 1.19 estimating the peak mf density at 01.11 hours. The influence of different times of blood collection on false negatives among the very low density carriers was estimated by the periodicity curve. It would be desirable to collect blood during the estimated time interval when the mf count was 80% of the peak count, between 21.55 and 04.27 hours in Matara. The results of 25 all-night mosquito landing catches gave a peak activity hours of k as 7.78, corresponding to 01.47 hours. CONCLUSION: The close agreement in the peak hours of mf density and vector activity suggests a perfect adaptation between parasite and vector for optimum transmission.

Filariasis in Bengkoka Peninsula, Sabah, Malaysia: bionomics of Mansonia sp.

Studies on age groups within activity cycles, age composition and survivorship in natural populations of Mansonia in Kampung Pantai, Bengkoka Peninsula of Sabah state have been described. Early activity of 3-5 parous Ma. bonneae during the first hour after sunset was noted. Age composition of Ma. bonneae at forest shade, indoor and outdoor of house, comparative buffalo vs human bait outdoor in Kampung Pantai showed all round high parous rates ranging from 66.7 to 75.4%. Population 3-parous and older ranged from 18.8 to 26.7%. Nine of the 14 infective Ma. bonneae were 3-parous and this segment of the population was engaged in active transmission. High parous rates were observed in Ma. dives and Ma. uniformis taken in small numbers. Parous rates of Ma. bonneae taken in Kampung Delima and Kampung Taradas were also high. Estimates of daily survivorship of Ma. bonneae and Ma. dives determined by two methods were very high.

Filariasis in Bengkoka Peninsula, Sabah, Malaysia: vector studies in relation to the transmission of filariasis.

Using seven methods of surveillance, 58 species of mosquitoes from nine genera were in Pantai and the two neighbouring villages during two visits in 1982. Ma. bonneae was the most prevalent species attracted to man. In the forest shade Ma. bonneae and Ma. dives showed activity throughout the 24 hours with peak biting during 1900-2100 hours. An. balabacensis exhibited peak activity shortly after midnight. Inside and outside house, Ma. bonneae showed similar activity except that it ceased during the day. Mansonia was only mildly zoophilic. CDC light traps gave poor yields of mosquitoes. Pyrethrum spray catch inside houses early morning did not include any Mansonia. Outdoor day resting catch included Ma. bonneae fed on man. Transmission of Brugia, probably human filariasis, by Ma. bonneae occurred in Pantai and in the two neighbouring villages. One infection in Ma. dives was found in Pantai. The monthly infective biting rate and monthly transmission potential for Ma. bonneae were estimated at the forest shade and outside the house in Pantai.

Significance of coconut husk pits as larval habitats of Culex quinquefasciatus (Say) in the filariasis endemic coastal belt of Sri Lanka.

Extended surveys of coconut husk pits in three districts in a study of vectors of Japanese encephalitis showed that Cx. gelidus constituted 50.9% of the larval material in Panadurra, 77.7% in Allutgama and 75.2% in Talalla. Correspondingly, Cx. quinquefasciatus was 0, 4.1 and 0 percent respectively. A similar survey in Polhena, Matara, a well known filariasis endemic village showed 72.2% Cx. gelidus and 21.2% Cx. quinquefasciatus. Analysis of past records of husk pit surveys from seven other districts gave similar results. The reason for relatively higher breeding of Cx. quinquefasciatus in the husk pits at Polhena, Matara and a suggested vector control strategy are discussed.