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Biomedical subjects

E Zielke

Publications and source records attributed to E Zielke.

34 records · Page 2Linked to original sources
PubMed1978

Abortive development of Wuchereria bancrofti in a West African strain of Culex pipiens fatigans.

The detailed morphology of the larvae of Wuchereria bancrofti developing in a refractory strain of Culex pipiens fatigans from Liberia, West Africa, has been described. The abortive development of the parasite in the thoracic muscles of the mosquito was characterized mainly by: (i) retardation or complete failure of initial division of the G-cell, (ii) partial or complete encapsulation of developing larvae, especially at the anal and excretory vesicle areas of late first-stage, (iii) breakdown of the forming internal structures with formation of clusters of DNA-and RNA-positive material, and (iv) anomalous development of some larvae in which extra-corporeal growth of internal tissues took place.

Africa, Western↗
PubMed1978

Dynamics and intensity of Wuchereria bancrofti transmission in the savannah and forest regions of Liberia.

In four villages in the savannah and in the rain forest of Liberia, regular assessment of the biting activity and infection rates of anthropophilic mosquitoes have been carried out through full annual cycles. The microfilaremia rates in the localities in the savannah were 18.3% and 20.0% and in those of the forest 10.3% and 12.5%. The all-night catches were performed inside ordinary inhibited houses at monthly or fortnightly intervals. Presence of infective larvae of Wuchereria bancrofti proved Anopheles gambiae, A. funestus and A. nili to be the local vectors. Biting densities were high in the savannah, and low in the forest. From the mosquito catches and the results of their dissections for filarial larvae it could be estimated, that during the observation year a person in the savannah villages would be bitten annually by 18,165 and 36,450 vector mosquitoes respectively, and would receive 236 and 536 infective bites with 570 and 1211 infective larvae. In the two forest villages the number of vector bites per person per year was calculated to be in the order of 6120 and 1102 of which 64 and 8 would be infective bites transmitting 101 and 8 larvae. The findings of considerable differences in transmission intensities between villages of the same bioclimatic zone and of comparable microfilaremia rates indicates instable epidemiological conditions in at least some of the localities investigated.

Animals↗
PubMed1977

On the inheritance of susceptibility for infection with Wuchereria bancrofti in Culex pipiens fatigans.

From a colony of C.p.fatigans from Monrovia showing 21.6% susceptibility of W. bancrofti a refractory strain could be selected but not a highly susceptible one. Experiments to select a refractory strain out of the highly susceptible colony from Delhi failed. From these results and those of the crossing experiments between the selected refractory strain from Monrovia and the Delhi colony it appears that in the mosquito population from Monrovia susceptibility for W. bancrofti is not dominating refractoriness while this is the case in the population from Delhi. Therefore, it is concluded that there will be at least two genetic factors controlling susceptibility for W. bancrofti in C.p.fatigans.

Animals↗
PubMed1977

On the escape of infective filarial larvae from the mosquitoes.

Experimentally infected females of Culex pipiens fatigans carrying infective larvae of Wuchereria bancrofti were fed, on the 16th day p.i., on four different solutions, which were offered "cold" (24 degrees C) or "warm" (34 degrees C) in Petri dishes as open fluids. Thus the sucking mosquitoes did not have to bend their labia. Only the "warm" human serum stimulated any considerable number of infective larvae (24.8%) to leave the mouthparts of the mosquitoes. 1289 infective C. fatigens females lost only an estimated 6.4% of their infective larvae of W. bancrofti, when they were maintained on sugar-water until their natural death. Most of the more heavily infected mosquitoes died relatively soon after the filarial larvae had reached maturity (15-20 days p.i.). The main stimulus provoking the filarial larvae to migrate into the labium is believed to be the movement of the muscles of the pharyngeal pump. Mature larvae protrude their anterior ends from the tip of the labellum. There they seem able to distinguish between suitable and unsuitable external conditions and accordingly they will either leave the proboscis completely or retract into the labium.

Animals↗
PubMed1977

On the development of onchocerca volvulus in mosquitoes.

In an attmept to find an experimental vector for Onchocerca volvulus which can be easily be bred under laboratory conditions, the susceptibility of Anopheles gambiae and Aedes aegypti to infection with O. volvulus was studied. The mosquitoes were fed on a membrane feeding apparatus containing microfilariae of O. volvulus. Whereas A. gambiae was refractory to infection. 14.9% of A. aegypti females became infected with developing stages, 11,2% showed young and mature third-stage larvae as well as some which had developed abnormally. However, no infective larvae of O. volvulus were found in the abdomen or the head of the mosquitoes.

Aedes↗
PubMed1976

Distribution and prevalence of Wuchereria bancrofti in various parts of Liberia.

A nightblood survey has been carried out in 82 localities situated in various parts of Liberia. A total of 8072 people have been examined for the presence of microfilariae of Wuchereria bancrofti and 403 (5.0%) have been found positive. However, the distribution of the disease was quite uneven. The infection was common in the coastal zone showing an average microfilaria prevalence of 9%, while in the forest belt among 5383 people living in rural areas only 109 (2.0%) were found to harbour microfilariae. In the savannah area out of 2198 people examined 209 (11.4%) persons were carriers of microvilariae.

Adolescent↗
PubMed1976

Studies on quantitative aspects of the transmission of Wuchereria bancrofti.

Feeding experiments with Anopheles gambiae and Culex fatigans infected with Wuchereria bancrofti showed that the mosquito females were losing about 20% of their worm burden when they were feeding on a blood chamber as well as on the guinea pig. 6.6% of all mature larvae found in the mosquitoes succeeded in entering the final host. A striking high infection rate was observed in those mosquitoes which refused to feed on a guinea pig. These mosquitoes have also to be considered when the loss of filarial larvae is calculated. Furthermore the experiments showed, that only very few larvae of Wuchereria bancrofti get lost when the mosquitoes are feeding only on sugar water solution.

Animals↗
PubMed1975

[On the migration of the third stage larvae of Wuchereria bancrofti in Anopheles gambiae (author's tranls)].

The migratory pattern of the third stage larvae of Wuchereria bancrofti from the thorax into the head of Anopheles gambiae has been studied. A total of 1269 infected mosquitoes were dissected and examined from the 7th through the 19th day after the blood meal. The filarial worms migrated from the thorax through the abdomen before they reached the head of the mosquito. Third stage larvae first appeared in the abdomen on the 9th day after infection, where their number increased progressively up to the 13th day and then decreased steadily thereafter. In contrast, mature larvae were first found in the head on the 11th day, and a concentration of larvae could be observed in this region only from the 14th day onwards.

Abdomen↗