Lymphoedema and its management in cases of lymphatic filariasis: the current situation in three suburbs of Matara, Sri Lanka, before the introduction of a morbidity-control programme.

Using in-depth interviews, information on the current state of lymphoedema management was collected from 101 cases of lymphatic filariasis with lymphoedema in three suburbs of Matara. The interviews were conducted prior to the introduction of a programme of community home-based care (CHBC) that incorporates modern lymphoedema-management strategies. Thirty-two of the interviewees had severe lymphoedema (of grade III or above). The male interviewees had significantly more entry lesions than the female. Most of the subjects had suffered from episodes of limb pain with fever, although the incidence of these episodes appeared unrelated to the severity of the lymphoedema. The frequency of the episodes of limb-pain/fever in the 12 months prior to the interviews appeared unrelated either to the level of daily hygiene, which was generally poor, or to the frequency of bathing. Many (65%) of the subjects paid no attention to limb care when bathing, and 44% did not use footwear. Over 80% made no effort to keep their afflicted limbs elevated, and 95% did not exercise. Most of the female interviewees felt shameful of their condition and were, in consequence, less likely to attend government clinics, for treatment, than the male interviewees. The drug treatment that the interviewees had received was often inadequate, and most had stopped seeking treatment because they had not perceived any significant treatment-attributable improvement in their condition. Modern lymphoedema-management strategies (based on regular washing, careful drying, and treatment, with antifungal, antibiotic or emollient creams, of the affected limbs, limb elevation, exercise, and use of footwear) had not reached the study communities and the local physicians were not aware of them. When dermatology life-quality indexes (DLQI) were calculated for the interviewees, the 26 most impaired subjects gave scores of 5-15 (mean=8.6). The DLQI for these subjects will be regularly re-evaluated, as a measure of the effectiveness of the CHBC programme that has now begun.

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.

Epidemiology of bancroftian filariasis in three suburban areas of Matara, Sri Lanka.

The epidemiological parameters of bancroftian filariasis were investigated in three suburbs of Matara, within the south-western coastal belt of Sri Lanka where the disease is endemic. The overall prevalence of microfilaraemia and the geometric mean density of the microfilaraemias observed were 4.4% and 20.6 microfilariae/60 microl fingerprick blood, respectively. Prevalence was significantly lower in the female subjects than in the male, and in males aged < 20 years than in older males. Overall, 9.5% of the subjects had the clinical manifestations of bancroftian filariasis (6.4% had filarial fever, 3.0% had elephantiasis and/or oedema, and 6.2% had hydrocele). The prevalence of elephantiasis/oedema was generally higher among the female subjects (4.2%) than among the male (1.4%), and an age-prevalence plot for this manifestation showed a linear increase in prevalence after the age of 40 years. Hydrocele also became commoner with increasing age, but this increase in prevalence began at the lower age of 20 years. More than 60% of the cases of elephantiasis/oedema but only 26.3% of the subjects found to have hydroceles experienced filarial fever attacks. The cases of fever and elephantiasis/oedema (but not those of microfilaraemia or hydrocele) were aggregated within households. However, the children whose mothers were microfilaraemic were much more likely to be microfilaraemic themselves (8.7%) than the children who had amicrofilaraemic mothers (2.8%), microfilaraemic fathers (0.0%) or amicrofilaraemic fathers (2.7%). The results of entomological surveys indicated that transmission of Wuchereria bancrofti occurred throughout the year in the study community.

Wuchereria bancrofti antigenaemia in Sri Lanka.

The prevalence of Wuchereria bancrofti antigenaemia determined in 353 subjects in Matara, Sri Lanka by Og4C3 ELISA was 20.7%. Positive rates obtained with the same subjects by 1 ml Nuclepore filtration and 60 microl thick blood smear were 11.3% and 7.9%, respectively. Antigen levels were positively associated with microfilaria counts. Two-thirds of antigen-positive and microfilaria-negative (Ag+/Mf-) individuals were > 25-year-old, but younger age groups (< or = 25-year-old) tended to have proportionally more Ag+/Mf- cases. Possible origins of the Ag+/Mf- status are discussed.

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.

The relative importance and distribution of Aedes polynesiensis and Ae. aegypti larval habitats in Samoa.

In preparation for a Filariasis Control programme in Samoa, during 1978 monthly larval surveys of the vector mosquito Aedes polynesiensis were carried out in four study villages in the main island of Upolu. A more extensive survey of larval habitat distribution was then made in twenty-two villages of Upolu and eighteen of Savai'i island, to determine the importance of habitat types according to their abundance, volume of water and whether their productivity was permanent or seasonal. Ae.aegypti larval densities and habitat distribution were also monitored and the occurrence of predatory Toxorhynchites amboinensis larvae in northern Upolu was recorded from forty-one collections. Aedes Breteau and container indices fluctuated with the pattern of rainfall in two coastal villages and an inland bush village, but not in a coconut plantation community. The five main Aedes larval habitat types encountered were: 200 litre water-storage drums, discarded tins and bottles, coconut shells, automobile tyres and treeholes. Aedes immatures occurred perennially in drums and tree holes, but breeding discontinued in tins, bottles and coconut shells during the driest month of July. For Ae. polynesiensis in Upolu the Breteau and container indices of 104.5 +/- SD 80.9 and 35.3 +/- 12.4 respectively were significantly higher than those in Savai'i: 33.1 +/- 25.0 and 24.3 +/- 20.0 respectively. Likewise for Ae.aegypti the Breteau and container indices of 50.8 +/- 32.5 and 23.9 +/- 15.6, respectively, were also significantly higher than those in Savai'i: 12.7 +/- 17.1 and 9.4 +/- 13.2 respectively. Habitat types greater or lesser importance were determined by plotting the percentage of each type of cotnainer utilized for Aedes breeding against the percentage of ech type amongst all larva-positive containers. Ae.polynesiensis preferred tree-holes but not water-storage drums. Ae.aegypti preferred drums and tyres; mixed populations of larvae of both species were commonest in these two types of habitat. Ae.polynesiensis occurred in every village. Ae.aegypti was encountered in all twenty-two villages surveyed in Upolu and nine of eighteen villages in Savai'i. Total larval surveys revealed that drums and tree-holes contained the highest numbers of Aedes larvae. The study provided criteria for planning a control programme.

Observations on Culex quinquefasciatus Say in relation to transmission of filariasis due to subperiodic Wuchereria bancrofti in Samoa.

Observations on Culex quinquefasciatus Say in Samoa during a study of the epidemiology and control of subperiodic bancroftian filariasis are reported. The man-biting rate of C. quinquefasciatus was comparable with that of Aedes (Finlaya) samoanus Gruenberg in one indicator village and lower in another. The house-frequenting behaviour of the two species was similar. Culex quinquefasciatus was active throughout the night with peak biting during midnight hours, and its survivorship, estimated by two methods, was higher than those of the main vectors, A. (Stegomyia) polynesiensis Marks and A. samoanus. Culex quinquefasciatus showed low susceptibility to subperiodic Wuchereria bancrofti, compared with the two main vectors, in laboratory feeding experiments on volunteers with three levels of microfilaraemia. This agrees with the observed very low natural infection rate, suggesting that C. quinquefasciatus is an inefficient vector of subperiodic W. bancrofti in Samoa.

Distribution of breeding and control of the filariasis vector Aedes samoanus in leaf axils of Pandanus in Samoa.

Water in leaf axils of the screwpine Pandanus was sampled for mosquito immature stages at seventy villages in Upolu, fifty-five in Savai'i and three in Manono, the main islands of Samoa. Ten plants in every patch of Pandanus plantation were sampled at each village. Among 23,049 mosquito larvae collected from Upolu, 77% were the filariasis vector Aedes (Finlaya) samoanus, 17.7% were Ae. (Fin.) oceanicus and 5.3% were Ae. (Fin.) tutuilae. Out of 6981 larvae taken in Savai'i, 23.2% were Ae. samoanus, 67.6% Ae. oceanicus and 9.2% Ae.tutuilae. When larval counts per plant were analysed for each district, Ae. samoanus was found to predominate in Pandanus in Upolu and Ae. oceanicus in Savai'i. However, the adult density of Ae.samoanus was higher in Savai'i and this was attributed to the large areas of forests with Freycinetia for Ae.samoanus breeding. In Pandanus in Savai'i the number of Ae.samoanus was negligible. In Upolu, with more urbanization and larger plantations, there was greater breeding of Ae.samoanus in Pandanus. Two control trials were conducted against Ae.samoanus larvae in Pandanus, one using a sand culture of the parasitic nematode Romanomermis culicivorax and the other with temephos, an organophosphate insecticide. While R. culicivorax did not adapt to the leaf axil habitat, all plants were without larvae for 5 weeks after treatment with temephos.

Seasonal abundance and biting behaviour of Anopheles punctulatus and An. koliensis in Malaita Province, Solomon Islands, and a trial of permethrin impregnated bednets against malaria transmission.

Seasonal abundance of the malaria vectors Anopheles punctulatus Dönitz and An.koliensis Owen in Bilimanu, an isolated inland village with forty-two houses in Malaita Province of the Solomon Islands, was monitored over 28 months by means of all-night landing/biting catches at one site during June 1985 to September 1987. Totals of 1250 An.punctulatus and 141 An.koliensis were collected, the latter being the largest number of this species ever caught at any locality in the Solomons. Bednets impregnated with permethrin 0.5 g/m2 were introduced in December 1986 to be used at night by all 190 villagers for protection against malaria vectors. Bioassay tests with An.punctulatus blood-fed females exposed under nets for 10 min resulted in 100% mortality up to 50 weeks post-impregnation. For An.punctulatus, the main vector species, the mean catch (indoors + outdoors) per man hour was 2.9 (range 0.7-13.2) before a cyclone on 19 May 1986, and, 0.66 (0.2-2.7) after the cyclone. The vector survival rates were usually high before the cyclone, but erratically lower thereafter for An.punctulatus. An.koliensis disappeared after the cyclone. Both An.punctulatus and An.koliensis consistently showed higher rates of biting man indoors than outdoors and their diel biting cycle showed a peak around midnight. Outdoors, the parous proportion of An.punctulatus was twice the nulliparous, and nearly so indoors. Following intervention with permethrin-treated bednets, the mean catch of An.punctulatus fell to 0.35 per man-hour (monthly range 0-1.5). The Plasmodium falciparum malaria infection rate reduced from 10% pre-intervention to zero in September 1987, 9 months after intervention, and then rose again.(ABSTRACT TRUNCATED AT 250 WORDS)

Natural infections of Dirofilaria immitis in Aedes (Stegomyia) polynesiensis and Aedes (Finlaya) samoanus and their implication in human health in Samoa.

Dirofilaria immitis infections were observed in Aedes polynesiensis and Ae. samoanus in Samoa, together with Wuchereria bancrofti infections, in a study on sub-periodic bancroftian filariasis during 1978-1980. In the 4 indicator villages, the infection rate in Ae. polynesiensis was 0.46% and the infective rate 0.09% (15,223 mosquitoes were dissected). The infection rate in Ae. samoanus was 0.20% and the infective rate 0.08% (10,089 dissected). In 45 selected villages throughout the country, Ae. polynesiensis infection and infective rates were 0.92% and 0.29% (7575 dissected) and the rates for Ae. samoanus were 0.21% and 0.07% (9093 dissected). Infection with D. immitis was comparable in degree and distribution to that with W. bancrofti. There was a steady and consistent exchange of parasites between the human and canine populations, creating conditions favourable for human dirofilariasis in Samoa. Clinicians are warned against this probable human infection.

Long-term efficacy of single-dose mass treatment with diethylcarbamazine citrate against diurnally subperiodic Wuchereria bancrofti: eight years' experience in Samoa.

A single-dose of diethylcarbamazine citrate (DEC, 6 mg per kg body weight) was administered in three mass treatment campaigns to > 80% of the estimated total Samoan population (160,000) in 1982, 1983, and 1986. The effect of the drug was evaluated before and after each campaign by conducting four blood surveys covering 9600 to 13,700 people from 26-34 villages on each occasion. The drug reduced the prevalence of Wuchereria bancrofti microfilariae from 5.6% to 2.5% (a 55% reduction), while the transmission potential (the estimated mosquito infection rate if everyone is equally exposed to mosquito bites) dropped from 2.18 to 0.67 (a 70% reduction). The total number of microfilariae in the Samoan population is estimated to have been reduced by 80%. A spaced, single-dose treatment with DEC at a 1-2-year interval therefore seems to be an effective control measure against diurnally subperiodic W. bancrofti.

The transmission of an avian filarioid Cardiofilaria nilesi to the jird, Meriones unguiculatus.

This paper reports the experimental transmission of a bird parasite into jirds. Infective larvae of Cardiofilaria nilesi obtained from laboratory colonized Coquillettidia crassipes mosquitoes which had fed on an infected chicken were inoculated subcutaneously into jirds. The number of larvae per jird varied from 10 to 228. Microfilaraemia appeared 22 to 89 days after inoculation of the infective larvae. Experiments were carried out with 24 jirds through six generations extending over a period of 22 months and 17 produced patent infections. At present 8 infected jirds are being maintained in the laboratory; their patent periods ranging from 6 to 13 months. However, the longest patent period observed was about thirteen months. The percentage of adults recovered in autopsied jirds ranged from 0 to 40 with an average of 16. The chicken showed a microfilarial periodicity with the peak microfilarial density around 2200 hours. However, in jirds there was a change in sub-periodicity. This model in the jird may be very useful for the screening of filaricides and in immunological work.

Natural infections of Wuchereria bancrofti in Aedes (Stegomyia) polynesiensis and Aedes (Finlaya) samoanus in Samoa.

Seven years after the 2nd mass treatment of the population with diethylcarbamazine, transmission of subperiodic Wuchereria bancrofti was studied in four villages in Samoa during one year by means of biting catches of Aedes polynesiensis and A. samoanus. 2 villages were coastal, one inland bush and the other an inland coconut plantation community. Overall infection and infective rates from 6702 Ae. polynesiensis were 0.84 and 0.27% respectively, and the infection rate from 2858 Ae. samoanus, collected in 10-minute catches from 24 sites, was 0.65%. No infective Ae. samoanus was found in these samples. 12-hour all-day catches in the 2 coastal villages confirmed active transmission by Ae. polynesiensis. 12-hour all-night catches in the same 2 villages recorded high transmission by Ae. samoanus although there was little evidence of local breeding. The annual transmission potential for Ae. polynesiensis and Ae. samoanus was high in one of the coastal villages and low in the other. A total of 221 infected Ae. polynesiensis and 40 Ae. samoanus were recorded. Of the 72 infective Ae. polynesiensis, 59.1% contained 1 to 2 larvae each (median density 1.4); 70% of the 40 infected Ae. samoanus had 1 to 2 larvae (median density 1.1). From the proportion of infective Ae. polynesiensis the mean probability of survival was estimated as 0.917.

Distribution of vectors, transmission indices and microfilaria rates of subperiodic Wuchereria bancrofti in relation to village ecotypes in Samoa.

Aedes polynesiensis and Ae. samoanus biting densities and Wuchereria bancrofti infection and infective rates were studied in 47 villages throughout the islands of Samoa Upolu, Manono and Savaii during 1978-79, and microfilaria (mf) rates were surveyed in 28 of the villages. The mf rate was correlated with both infection and infective rates of Ae. polynesiensis in Upolu, but not of Ae. samoanus. In Upolu, Ae. polynesiensis was apparently the major vector. It was relatively more abundant in more cultivated and populated areas, along the northern coast of Upolu, except Apia town area. In Savaii, Ae. samoanus predominated over Ae. polynesiensis except in "plantation" villages. Relatively high biting densities and rates of infection and infectivity indicated that Ae. samoanus was not less important than Ae. polynesiensis as a vector in Savaii. Ae. samoanus preferred natural vegetation, in contrast to Ae. polynesiensis which was found near human habitations in cultivated land. There was no difference between the biting densities of Ae. polynesiensis in "coastal" and "inland" villages, indicating that crab holes (numerous only in some coastal villages) may not influence the density of Ae. polynesiensis. Higher mf rates were associated with villages where Ae. polynesiensis, rather than Ae. samoanus, was dominant, indicating that Ae. polynesiensis was generally a more efficient vector. In the former villages, the difference in mf rates between males and females was smaller than in the latter, probably reflecting a difference in biting habits of the vectors. Ae. polynesiensis infections were recorded in plantations over 2 km from any village, suggesting that both habitats were foci of transmission.

Field studies on the surveillance of Coquillettidia crassipes (Van der Wulp) and the isolation of a strain of Cardiofilaria in peninsular Malaysia.

Surveillance methods for Coquillettidia crassipes were studied in an open housing estate near Kuala Lumpur using three types of traps Trinidad 10 trap, modified Lard can trap and IMR trap, each baited with chicken or pigeon. All traps attracted Cq. crassipes. There was no significant difference in the catches in the three traps. There was also no significant difference between chicken and pigeon as bait. Catches at heights of 1.5, 3, 4.5 and 6 m did not show any significant difference in density. Cq. crassipes was active at night with an early peak during the first hour of the night and a minor peak between 0100 and 0200 hours. The activity of the parous and nulliparous sections of the population was similar, except that a higher proportion of the parous females was active during the second peak compared with the nulliparous females. The parous rate was 22.3%, and the probability of survival through one day for two gonotrophic cycles was 0.711 and 0.650. The infection rate for Cardiofilaria was 29 out of 1052 (2.76%) and the infective rate (L3 larvae) was 13 out of 1052 (1.24%). 48.3% of the infected Cq. crassipes had a worm burden of more than ten larvae. One of the chickens in the traps was positive for microfilariae of Cardiofilaria four weeks after exposure as bait. Laboratory bred Cq. crassipes fed on this chicken produced infective larvae in ten days, and these were inoculated into clean chickens and pigeons. Microfilariae appeared in the chickens but not in pigeons. The adult worms recovered await identification.

Field and laboratory observations on Coquillettidia crassipes in relation to transmission of Brugia malayi in Peninsular Malaysia.

Field observations were made on Coquillettidia crassipes during a study of Mansonia in a swamp forest ecotype in Tanjong Karang. There was an increase in abundance in July consistent with the increase in abundance of Mansonia and an increase in rainfall. The biting cycle showed a dramatic early peak during the period 1900-2000 hours. The probability of daily survival through one day for the first three gonotrophic cycles was 0.770, 0.722 and 0.759. Two of the 54 Cq. crassipes dissected were infective, with two and 25 L3 larvae of Brugia. Both subperiodic B. malayi and B. pahangi developed into L3 larvae in laboratory bred Cq. crassipes. The index of experimental infection was higher for B. pahangi. Mansonia bonneae and Ma. uniformis showed higher indices of experimental infection than Cq. crassipes for subperiodic B. malayi. It is concluded that in an endemic area with a high density of Cq. crassipes it could act as a secondary vector of Brugian filariasis.