Tolerability and efficacy of a three-age class dosage schedule of Diethylcarbamazine citrate (DEC) in the treatment of microfilaria carriers of Wuchereria bancrofti and its implications in mass drug administration (MDA) strategy for elimination of lymphatic filariasis (LF).

A six-age class dosage schedule of Diethylcarbamazine (DEC) of 50mg (1-2 years), 100mg (3-4 years), 150mg (5-8 years), 200mg (9-11 years), 250mg (12-14 years) and 300mg for above 14 years is being adopted for annual single dose MDA for LF elimination treat Wuchereria bancrofti microfilaria carriers. In order to increase the community compliance as well as to make the distribution easier during MDA, a revised 3 age class dosage schedule of 100mg (2-4 years), 200mg (5-14 years) and 300mg for above 14 years was evaluated for its tolerability and efficacy. By this change, it was observed that the 4-8 years age class is receiving 50 mg higher and 11-14 years age class is receiving 50mg lesser dose compared to the earlier class schedule. Therefore, the safety aspect in the age class of 4-8 years and efficacy component in the age class of 11-14 years were assessed. Apparently "healthy" asymptomatic microfilaraemic volunteers between the age class of 4-8 and 11-14 years were recruited for the study. The incidence of side reaction in the 4-8 years age class was 50.0% with 150mg dose and 66.7% with 200mg (P>0.05). No life threatening adverse reactions was observed in any dosage schedule. Fever, headache and myalgia, the predominant adverse reactions were mild and similar in both schedules. The mean intensity of the three major specific adverse reactions (fever, headache and myalgia) also did not differ significantly (P>0.05). For the purpose of LF elimination, efficacy in terms of reduction in mean microfilaria load is important. In the 11-14 year age class considerable reduction in the geometric mean density (GMD) was observed by day 90 and 180 post-therapy in both groups (250mg group and 200mg group) compared to pre-therapy level. By day 360 post-therapy, the difference was statistically not significant (P>0.05) (reduction of 72.2% in 250mg and 69.6% reduction in 200mg). The reductions in GMD were statistically significant when compared to pre-therapy levels in both the old (250mg) and new (200mg) doses. Thus, three- age class dosage schedule is as safe and efficacious as the six- age class schedule.

Management of disability in lymphatic filariasis--an update.

The global lymphatic filariasis elimination programme incorporates disability management along with transmission control, to ensure 'a visible impact' on those who are already affected by the disease. The common manifestations of lymphatic filariasis like lymphoedema; elephantiasis and hydrocele result from irreversible damage caused to the lymphatics by the adult worms. Only palliative treatment in the form of physical methods and surgery is available for lymphoedema and elephantiasis. Hydrocele can be corrected by surgery. The most distressing aspect of lymphatic filariasis is the attacks of acute adenolymphangitis, which cause considerable short-term and also long-term disability by worsening the lymphoedema. Since each episode prevents the person from attending his work for several days, the economic loss is substantial. The precipitating cause of these attacks is secondary infection, the bacteria entering the tissues through 'entry lesions' in the skin. These episodes can very well be prevented by proper 'local-hygiene' of the affected limbs, which is a simple, effective, cheap and sustainable method that can be carried out even in the patient's house. These subjects and the providers of 'home care' should be trained in foot-hygiene programme, so that the message percolates to various levels in the affected communities, ultimately benefiting the patient.

Experimental infection of Culex (Culex) quinquefasciatus and Aedes (Stegomyia) aegypti with Wuchereria bancrofti

A study was conducted to determine the susceptibility of local strains of Culex quinquefasciatus and Aedes aegypti to infection with the strain of Wuchereria bancrofti that occurs in Maceió, State of Alagoas, Brazil. Cx. quinquefasciatus blood fed simultaneously on the same microfilariae carrier ingested more blood and 2-3x more microfilariae than Ae. aegypti. Survival rates of both species of insects living for 21 days after blood feeding on microfilaraemic patients were not significantly different from the survival rates of mosquitoes that blood fed on amicrofilaraemic individuals. W. bancrofti parasites underwent normal development in Cx. quinquefasciatus, with third stage larvae first being recorded on the 11th day post infection, and their numbers increasing thereafter. Development of filariae in Ae. aegypti did not proceed beyond the first larval stage, and there was a progressively increasing number of non-viable larvae with the passage of time. It is concluded that Ae. aegypti is not involved in the transmission of W. bancrofti in Maceió.

Report study on chyluria

A case of chyluria is repored, detected in a non-endemic area, although the patient hails from an endemic belt in India. The chronicity and reinfection theoty leading to this complication of filariasis caused by the nematode wuchereria bancrofti are confirmed. Various investigative and treatment aspects and preventive measures are discussed

Filariasis transmission potential of mosquitoes to humans of different age groups

Age-specific levels of Wuchereria bancrofti infection determined by microfilaremia in filarious 10 to 60 years old males from an endemic village revealed that microfilaria intensity was higher in younger age, presumably because of increased vector biting rate of younger individuals. Out of 1334 Cx. pipiens captured while attempting to bite 51 child-adult bait pairs, 54% selected a host in the 10 - 15 age group. Biting preference towards children was more elevated [79.2%] later than earlier in the night. Frequency distribution of age- specific biting collections indicated that 62.7% recorded exceeding numbers of bites on children, 21.6% adult biting, and 15.7% equal biting of one of the baits in the pair. Furthermore, 21.6% of the children were exposed to nightly bites ranging from 21 to 64 and only 7.8% of the adults experienced from 21 to 85 bites. Mosquito biting intensity averaged 14.2 and 11.6 bites/night for children and adults, respectively. Children experienced 22.4% more bites per night than adults. Thus, children are more exposed to filaria infection and seem to represent an important source of infection. It is concluded that attempts at widespread control of filariasis in the densely populated Nile Delta, where youngsters may account for an immense proportion of the local population should concentrate on immatures

Host-parasite relationships of wuchereria bancrofti and mosquito hosts, culex pipiens L and aedes caspius pallas

The reciprocal deleterious effects of both the mosquito host and its parasite were reported. Anatomical and histological examinations of mosquitos revealed minor differences in the general structure of the foregut of either species. However, the cibarial pump of Ae. caspius lacked a cibarial armature and damage inflicted to some of the microfilariae [mf] ingested by this mosquito was not mechanical. In contrast, the cibarial armature of Cx. pipiens consisted of 24 delicate teeth, which did not seem to affect ingested mf. The peritrophic membrane [pm] did not constitute a significant barrier to mf, migrating through the midgut wall of either mosquito. Traversing mf perforated the pm and displaced the basement membrane. Within the thorax of Cx. pipiens, the parasite completed its development synchronously. In contrast, mf ingested by Ae. caspius did not develop beyond the sausage stage and many of these larvae were vacuolated. In both mosquitos, parasitized thoracic muscle fibers were tunneled and only in Ae. caspius, their nuclei were pyknotic. No worm encapsulation or melanization was observed in either mosquito

Uptake and development of wuchereria bancrofti in culex pipiens L and aedes caspiuspallas

Studies were conducted to compare early phenomena associated with W. bancrofti infection and further development in the filaria vector Culex pipiens and the refractory mosquito Aedes caspius. Ingestion rates evaluated immediately after simultaneous feeding on an infected human were 69.1% for 43 Cx. pipiens and 35.7% for 28 Ae. caspius. The observed number of mf ingested by either mosquito did not vary significantly [2.7 +/- 1.4, and 2.3 +/- 0.9, respectively] and, based on the size of the blood meal ingested [2.8 and 2.3 mul, respectively], a 2-fold mf concentration factor was recorded for both species. Blood ingested by Cx. pipiens [N = 16] and Ae. caspius [N = 10] clotted within 120 and 90 minutes post-feeding, respectively. The time difference observed however, did not affect significantly the rates of migration into the hemocele [56 and 67%, respectively]. Comparison of initial infection rates with those obtained after the extrinsic incubation period of the parasite was completed, indicated that the proportion of infected Cx. pipiens was reduced by 3.9% and that of Ae. caspius by 30%. Furthermore, the observed infectivity ratio of 265 Cx. pipiens that had an infective blood meal was 0.74 and only 0.009 for 70 Ae. caspius

Study of filariasis in Qualioubia governorate, Egypt

Seven hundred and fifty individuals were chosen randomly from five centers known to be endemic for filariasis in Qualubiya Governorate. These were Benha, Tokh, Qalyub, EI Khanka and Shebin EI-Kanater centers. Case sheet was designed to cover personal, present and past histories for filariasis. Thorough clinical examination was performed. Blood samples [taken at 10 p.m. -2 a.m.] were examined by wet preparation and counting chamber techinque. Microfilariae were detected in 68 cases [9.07%]. There was no statistical significance between positive cases as regards sex [p > 0.05] but there was high significance as regards age [p < 0.01]. The range of density of microfilariae in 1 ml venous blood was 10.7 - 34.18 [mean 22.5 /ml] and in 5 ml 47-176 [mean 111.5/5ml]. Fifty four cases [7.2%] showed clinical manifestations for filariasis [11 microfilaraemic and 43 amicrofilaraemic] in the form of limb itching, limb swelling, elephantiasis in one or more limb, hydrocele and chyluria. There was positive correlation between percentage of clinical cases and microfilaraemia [P<0.05] and no correlation between it and density of micro filariae [P<0.05]

Exposure variables in bancroftian filariasis in the Nile Delta

To demonstrate focality of filariasis within endemic rural areas and to define exposure variables which may influence this phenomenon, the population of an agrarian endemic village, of 12,500 individuals, in the Nile Delta of Egypt was censused. A sequential sample of individuals residing in every 5th house was tested for microfilaremia 239 households with 8.6 +/- 3.5 individuals per household [HHD]. Three areas of the village were tested simultaneously and a questionnaire was filled out for each sampled HHD with special emphasis given to the entomological and environmental factors that might affect filarial infection

Vector competence of autogenous and anautogenous culex pipiens mosquitoes for wuchereria bancrofti

Vector competence of autogenous and anautogenous Culex pipiens derived from North Sinai Governorate, Egypt, for the human filaria parasite Wuchereria bancrofti was studied. After feeding on the same microfilaremic volunteers both biotypes were readily infected with the parasite [infection rates > 80%] and supported its development to the infective stage within 11 - 12 days. Infective rates of both autogenous and anautogenous mosquitoes were similar [> 95%]. However, autogenous Cx. pipiens developed significantly less number of infective stage larvae [4.7 +/- 1.4 1.3 / female] than did anautogenous siblings [6.7 +/- 3.6 L[3]/ female] [P < 0.05]. Moreover, autogenous females were observed to contain twice the number of L[3] larvae in the thoracic muscles and less larvae in the head region compared to autogenous counterparts. Vector competence characteristics of Cx. pipiens derived from a filariasis endemic area in Qalubiya Governorate were similar to those of anautogenous mosquitoes of North Sinai. These findings indicate that autogenous Cx. pipiens may be less efficient vector of W. bancrofti in endemic areas of Egypt

Antifilarial IgM versus IgG antibody determination in the diagnosis of wuchereria bancrofti infection in Egyptians

Circulating antifilarial IgM and IgG antibodies were assessed by indirect ELISA in 184 serum specimens from 80 patients with clinically and parasitologically diagnosed filarial infections [20 with acute filariasis, 40 with chronic filariasis, and 20 asymptomatic microfilaremic subjects], 64 individuals with other parasitic infections, 20 parasitologically free subjects from filariasis endemic areas and 20 normal healthy controls. A soluble surface membrane extract from Dirofilaria immitis worms was used as the antigen. Using a single serum dilution of 1: 128 and optical densities [OD] at 492 rm, the respective cut off values for IgM and IgG were found to be 0.24 and 0.22. All healthy nonendemic controls were seronegative by IgM and IgG ELISA. The highest antifilarial IgM OD492 values were obtained in 20 patients with acute filariasis [95% sensitivity], while the highest antifilarial IgG OD492 values were observed in 40 patients with chronic filariasis [97.5% sensitivity]. Asymptomatic microfilaremic subjects gave IgM and IgG OD492 values which were significantly lower than those of other forms of clinical disease and endemic control subjects. The antifilarial IgM and IgG respective sensitivities in asymptomatic subjects were 75% and 70%. Endemic controls had positive antifilarial IgM [65%] and IgG [75%] levels. Of 64 subjects with other parasites, only one with Ancylostoma duodenale had positive IgM level [98.4% specificity]; while, 9 patients with nematodal infections mainly had false positive antifilarial IgG antibody levels [85.9% specificity]. These results suggest that measuring circulating antifilarial IgM antibody level may have some diagnostic advantage over measuring IgG antibody level for the detection of active filarial infection and consequently better management of the diseases

Mosquito age as a factor influencing the transmission of wuchereria bancrofti

Two mosquito Species; Culex pipiens and Aedes caspius of different ages were experimentally infected with moderate microfilarial densities of Wuchereria bancrofti and examined for their vector potential to transmit this parasite. Tested age groups of Cx. pipiens supported the development of the infective stage of the parasite [L3] but those of Ae. caspius arrested its development especially aged mosquitoes. For Cx. pipiens, infection rates and the mean number of microfilaria [mf] were found decreased with insect age groups while their survival was not affected. Also, proportion of mosquitoes harbouring L3 of the parasite was quite similar for the examined age groups, however; the 4 days-old group was the highest. On the other hand, Ae. caspus capability to respond against W. bancrofti Was decreased in older mosquitoes. The observed results may indicate certain influence of mosquito aging on the development of W. bancrofti which differ according to mosquito species