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PubMed1983

Ultrastructure of Mansonella ozzardi microfilaria, with a comparison of the South American (simuliid-transmitted) and the Caribbean (culicoid-transmitted) forms.

Ultrastructural studies conducted to elucidate and compare the microanatomy of the South American (simuliid-transmitted) and the Caribbean (culicoid-transmitted) microfilariae of Mansonella ozzardi revealed that these microfilariae are essentially identical. The only difference detected was the larger central body of the Colombian microfilariae. Although the microanatomy of M. ozzardi microfilaria is essentially the same as that of other microfilariae, some of the subtle differences noted between M. ozzardi and other microfilariae include: amphids of unequal lengths, a large nucleus located approximately 30 microns from the anterior end, and an esophagus which appears to be less developed than that of Loa loa and Brugia spp. The microfilaria has a small cephalic hook, intracellular bacteriae in the hypodermal cells, and crystalloid inclusions which are most prominent in the R-1 cell and are also present in the hypodermal and esophageal cells. These crystalloids appear to be unique to M. ozzardi microfilariae.

Animals↗
PubMed1984

Onchocerciasis in Venezuela: prevalence of microfilaraemia in Amerindians and morphological characteristics of the microfilariae from the Upper Orinoco Focus.

Data are presented on microfilaraemia in 191 Yanomami Amerindians from two areas of Venezuela's Upper Orinoco Basin, where an endemic focus of onchocerciasis has been recently detected. Onchocerca microfilariae were found in the blood of 12.6% of the persons examined. In the village with the higher number of examined individuals (N = 162), the prevalence of microfilaraemia in the age groups covaried with the prevalence of microfilariae in the skin and with the parasite load (mf/mg of skin). A positive correlation was found between age and these three variables. The prevalence of Onchocerca microfilaraemia in the Upper Orinoco focus is high, and may be related to the ability of the strain to invade the blood stream. Morphobiometric characteristics of the Onchocerca microfilariae isolated from human blood are similar to those of O. volvulus fixed in formalin from skin and from the uterus of female O. volvulus worms. All have a very short cephalic space. Comparisons with the entity from the Upper Caura river designated as Microfilaria bolivarensis were also made. It was concluded that there are no valid biometric differences in thick blood smears between microfilaria bolivarensis and microfilaria of O. volvulus from the Upper Orinoco deme. A more striking difference may be in the concentration of microfilariae observed in the blood, which in one case of mf. bolivarensis was more than forty times the highest number recorded for microfilaria O. volvulus in Parima.

Adolescent↗
PubMed1994

Ivermectin-induced cell-dependent lethal effects on litomosoides carinii microfilariae in vitro.

Ivermectin affected the motility of Litomosoides carinii microfilariae in vitro in a dose dependent manner but did not completely immobilize the larvae and had no lethal effects when tested up to a concentration of 1000 ng/ml. However, killing of microfilariae was induced by ivermectin in vitro in the presence of spleen cells of Mastomys coucha or rats within 14 h. Optimum effects occurred at drug levels of 10-100 ng ivermectin/ml. Addition of infection serum led to increased cytotoxicity when compared with normal serum. Pretreatment in vitro of L. carinii microfilariae with ivermectin in cell-free medium and subsequent exposure to spleen cells caused also cytotoxic effects which appeared to be accelerated in comparison with simultaneous exposure of microfilariae to ivermectin and cells. Pretreated microfilariae, injected intravenously into naive M. coucha were rapidly eliminated from the blood of the recipients. These results suggest that the microfilariae become altered by the drug and thus susceptible to cell-mediated cytotoxic effects. Cytotoxicity did not depend on the attachment of cells to L. carinii microfilariae and was also induced when targets and effector cells were separated by membranes impermeable for cells. Thus ivermectin-induced cellular cytotoxicity to L. carinii microfilariae is at least partly mediated by soluble factors released by effective cells.

Animals↗
PubMed2002

Microfilariae of Wuchereria bancrofti in cyst fluid of tumors of the brain: a report of three cases.

Microfilariae of various nematodes, including Loa loa, Dirofilariae, and Onchocerca volvulus, have been identified in the central nervous system (CNS). The CNS, however, is a rare site for the isolation of microfilariae of Wuchereria bancrofti. To the best of our knowledge, the presence of microfilariae of W. bancrofti in tumor cyst fluids or cerebrospinal fluid has not been reported to date. We report three cases in which microfilariae were identified in the cyst fluid of tumors of the brain. Cyst fluid aspirated from space-occupying lesions in the thalamus and C6-D1 spinal segments in a 46-yr-old man and a 35-yr-old man, respectively, showed numerous microfilariae of W. bancrofti, along with fragments of tumor suggestive of glioma. In the third case, in a 12-yr-old boy, the fluid from the space-occupying lesion in the third ventricle showed microfilariae in a necrotic dirty background with a few squames and cholesteral crystals. Histopathologic examination of the tumor showed an anaplastic astrocytoma and a low-grade astrocytoma in the first two cases, respectively, and a craniopharyngioma in the third case. No microfilariae were identified on the histology sections.

Adult↗
PubMed1995

Comparison of migration and encapsulation of Brugia malayi microfilariae from the midgut to the hemocoel between Anopheles quadrimaculatus and Aedes aegypti.

Comparisons were made of migration and encapsulation of ingested sheathed microfilariae of Brugia malayi from the midgut into the hemocoel between Anopheles quadrimaculatus (refractory and susceptible strains to B. malayi) and Aedes aegypti (Black-eyed, Liverpool strain susceptible to B. malayi). Encapsulation and melanization of microfilarial sheaths and microfilariae occurred in both strains of An. quadrimaculatus and in Ae. aegypti. In both strains of An. quadrimaculatus, by 4 hr and by 24 hr after the ingestion of sheathed microfilariae of B. malayi in the infected bloodmeal, significantly more sheathed microfilariae penetrated the midgut and reached the hemocoel and thoracic muscles compared with those in Ae. aegypti. During the same time periods significantly more encapsulated and melanized microfilarial sheaths and a larger percentage of encapsulated and melanized microfilariae were observed in the hemocoel of both strains of An. quadrimaculatus than in Ae. aegypti. The results suggest that differences observed in the numbers of encapsulated and melanized microfilarial sheaths and percentages of melanized microfilariae between An. quadrimaculatus (both strains) and Ae. aegypti are due to different rates of penetration of the sheathed microfilariae from the midgut to the hemocoel.

Aedes↗
PubMed1988

Biochemical and immunochemical characterization of surface and excretory-secretory antigens of Loa loa microfilariae.

Detergent solubilized extracts of 125Iodogen surface-labelled Loa loa microfilariae revealed a relatively simple profile of two strongly labelled molecules of 23 and 67 kDa for blood microfilariae and several strongly labelled molecules of 23, 40, 42-67 kDa for in vitro born microfilariae. In addition, there were other weakly labelled molecules which were resolved after prolonged autoradiographic exposure. Surface molecules of 28, 29, and 33 kDa were unique to blood microfilariae, a 14.4 kDa molecule was unique to in vitro born microfilariae and molecules of 23, 40, and 75-84 kDa were common to both forms of microfilariae. The profile of excretory-secretory products consisted of molecules of 14.4-198 kDa. Human albumin was a predominant component of surface molecules and excretory-secretory products from blood microfilariae. Immunoprecipitation with occult and microfilaremic loaiasis sera demonstrated that the 23 kDa surface molecule and excretory-secretory products of 14.4 and 33 kDa were only recognized by occult loaiasis sera whereas surface molecules of 40 and 75-84 kDa and excretory-secretory products of 28 and 67 kDa were recognised by both sera. Studies with heterologous sera demonstrated that with the exception of the 75-84 kDa antigens, all the L. loa microfilarial surface antigens contained epitopes which were restricted to filarial parasites. Further studies revealed that the 23 kDa antigen was a protein which contained neither asparagine-N-linked oligosaccharides nor interchain disulfide-linkages.

Animals↗
PubMedDate not supplied

Onchocerca ochengi transmission dynamics and the correlation of O. ochengi microfilaria density in cattle with the transmission potential.

The intensity of natural transmission of Onchocerca ochengi and Onchocerco volvulus by anthropo-boophilic Simulium damnosum s.l. was studied longitudinally in two cattle watering sites of a cattle ranch within a predominantly cattle populated area of the Guinea savanna of Cameroon and related to cattle O. ochengi skin microfilaria abundance. During the 12 months study period, a total of 4696 flies was individually dissected to examine the monthly transmission potential (MTP) of O. ochengi and O. volvulus. The estimated Simulium damnosum s.l. annual biting rates (ABR) on human baits were 47529 flies at the bank of the Vina "du sud" river. The ABR at the lake, which was situated at about 2 km upland from the perennial river, was 8579. The monthly parous rate was highly correlated with monthly biting rate. The annual transmission potentials (ATP) of O. ochengi were calculated to be 7732 and 1669 at the riverbank and the lake, respectively. Transmission occurred mainly in the dry season, peaking in the months of January to mid-March when dermal microfilaria density in the animals was also the highest. The O. ochengi microfilaria uptake by the fly vectors was host microfilaria density-dependent. The MTP of O. ochengi was positively correlated with dermal microfilaria density. The mean number of microfilariae per fly taken up during a blood meal was high during the dry season as was the mean number of infective larvae per fly but declined significantly with the onset of the early rains. A similar seasonality of transmission was also observed for O. volvulus that was concurrently transmitted by the same vector flies, but its ATP was comparatively much lower: 1332 infective larvae per man per year at the riverbank and 107 around the lake. The population dynamics of cattle microfilariae therefore plays an important role in the regulation of O. ochengi transmission.

Animals↗
PubMed2005

Molecular evidence for host specificity of parasitic nematode microfilariae in some African rainforest birds.

Here we describe, determine the prevalence, and examine the host-specificity of some parasitic nematode microfilariae in selected bird species from West and Central Africa. We used microscopy to determine the prevalence of microfilariae in 969 host individuals representing 121 rainforest bird species from Cameroon, Côte d'Ivoire and Equatorial Guinea. Thirteen (11%) of these potential host species harboured microfilariae, and 35 individuals (3.6%) were infected. From the 35 infected individuals, we identified eight distinct morphological microfilarial forms. Sixteen of the 35 infected individuals were of one host species, the Fire-crested Alethe (Alethe diademata), at a prevalence rate of 62%. To examine host and geographical specificity, we sequenced a portion of the LSU rDNA gene from representative microfilariae drawn from different hosts and collecting locations. Identical sequences of the nematode LSU rDNA gene were found in A. diademata collected from locations in Côte d'Ivoire and Equatorial Guinea, locations separated by the Dahomey Gap and associated with different hypothesized refugial areas. In contrast, several other bird species collected at the same sites harboured different microfilaria lineages. We sequenced the mitochondrial ATP synthase genes of the host species A. diademata, and found a 5.4% sequence divergence between the birds sampled in Côte d'Ivoire, and those from Cameroon. Thus, despite this split between the two populations, they harbour microfilariae with identical lineages. These data provide evidence that the microfilariae found in A. diademata may be highly host specific. This apparent specificity may have important implications for the evolutionary and ecological interactions between parasitic nematodes and their avian hosts.

Animals↗
PubMed1982

Brugia malayi microfilariae from the peritoneal cavity of jirds vary in their ability to penetrate the mosquito midgut.

Development in mosquitoes of Brugia malayi microfilariae obtained from the blood of jirds was compared to that of microfilariae from the peritoneal cavity. Penetration of the mosquito midgut wall as well as development into third-stage larvae was assessed. About 70% of blood-borne microfilariae penetrated the midgut wall whether ingested directly from a microfilaremic jird or from a membrane feeder containing blood from the same donor. In contrast, less than 30% of microfilariae from the peritoneal cavity penetrated the midgut wall. Microfilariae in the peritoneal cavity of jirds vary in ability to penetrate the midgut of mosquitoes; some penetrate as rapidly as do blood-borne microfilariae, others penetrate more slowly, and most fail to penetrate the midgut. Regardless of origin, microfilariae that penetrated the midgut wall developed into third-stage larvae.

Aedes↗
PubMedDate not supplied

Haematological parameters in prospective nigerian blood donors rejected on account of anaemia and/or microfilaria infestation.

BACKGROUND: Worldwide, prospective blood donors are screened for blood transfusion-transmissible diseases. In addition, predonation fitness requires adequate haematocrit and, in the tropics, negative screening for microfilaria that may precipitate allergy. The high prevalence of anaemia and microfilaria, though treatable, has contributed to the dearth of eligible blood donors. This study aims to characterize anaemia in prospective blood donors rejected for anaemia and find haematological effects of microfilarial infestation in prospective blood donors. METHODS: This prospective study was carried out from 1st of August to November 30th, 2002 at the blood transfusion unit of the Haematology Department of Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC), Ile-Ife. All consenting prospective blood donors that were rejected for anaemia and or microfilaria infestation during the study period were studied for their age, sex and haematological profile. A randomly selected population of successful donors was similarly studied. RESULTS: Sixty rejected prospective blood donors (5.2% of the total screened)) were studied. Forty-five (75%) of them were rejected for anaemia alone, 10 (16.7%) for microfilaria alone and 5 (8.3%) for both anaemia and microfilaria. The mean ages of those rejected were 33.3(+/- 9.9) years for anaemia alone, 29.9(+/- 8.5) years for microfilaria alone and 35.4(+/- 8.3) years for those with anaemia and microfilaria combined. The mean age of the successful group was 28.9(+/- 8.5) years. Of the 60 rejected subjects, 53 were males while 7 were females. Blood film of the anaemia group revealed features suggestive of iron deficiency anaemia (hypochromic microcytic cells) in 60% of them. The white cell count (WCC) was significantly increased in the microfilarial group compared to others and it revealed lymphocytosis and eosinophilia. CONCLUSION: The importance of these findings have been discussed in line with the existing literature. The need for intensive health education to encourage voluntary donation and promote the interest of females in blood donation is emphasized.

Adult↗
PubMed2005

Susceptibility of Mansonia uniformis to Brugia malayi microfilariae from infected domestic cat.

Microfilariae of Brugia malayi is transmitted to man and other susceptible hosts via mosquito. The transmission of B. malayi from cat to man by Ma. uniformis bite has never been reported. The Ma. uniformis mosquito is the normal vector for Wuchereria bancrofti but has never been reported as a vector for B. malayi, or a susceptible host for the growth and development of the microfilariae of B. malayi. The purpose of this study was to examine the development of B. malayi in Mansonia uniformis after feeding on the blood of an infected cat in the laboratory. The B. malayi infected cat was identified using PCR with the primers Bm-1/Bm-2 on DNA (at 10 ng/50 microl) extracted from the WBC of the cat. W. bancrofti was employed as a negative control. The sensitivity of the B. malayi DNA detection by PCR was 0.0001 ng. Adult Ma. uniformis mosquitos at the ages of 5, 10, and 15 days, 100 mosquitos in each group, were fed on the infected cat blood. Recovery of third stage microfilariae was found to be the highest in the 5-day old mosquito group (48%), followed by the 10- and 15-day old mosquito groups (32% and 18%, respectively). The mean number of B. malayi microfilariae found in thorax, head, and abdomen of the mosquitos were composed. The 5-day old (40.3%) and 10-day old (41.9%) mosquitos were significantly more susceptible to microfilariae than the 15-day old mosquitos (17.8%) (p-values using the Scheffe method: 0.027 and 0.039, respectively). There was no significant difference in the mean number of microfilariae in the thorax (p = 0.482) by age, but the mean numbers of microfilariae in the heads, and abdomens were significantly different by age between the 5- and10-, and the 15-day old mosquitos (p < 0.001 and p = 0.004, respectively).

Animals↗
PubMed1989

The relationship between microfilarial density and uptake of Foleyella candezi microfilariae by Aedes aegypti.

There was a linear regression in the square root of the numbers of microfilariae abstracted (square root of y) by Aedes aegypti refm strain on the square root of the density of microfilariae in the infecting blood (square root of x). The linear regression is represented by the equation, square root of y = 0.080,59 square root of x + 4.556 (r = 0.627; P less than 0.01). - Ae. aegypti abstracted microfilariae about 1.60 times that expected from the infecting blood meal. This value however decreased, when the microfilariae in the infecting blood meal increased possibly due to error in counting large numbers of microfilariae. - The volumes of blood ingested by three strains of Aedes aegypti (+fm/+fm, refm/refm, reF/reF) appeared to be unaffected by genes controlling susceptibility or refractoriness to filariae (Foleyella candezi). - The Duncan's multiple range test showed similarity (p greater than 0.01) in percentage uptake efficiency, 157.28 and 164.28 for black-eyed homozygous susceptible and red-eyed homozygous susceptible strains respectively. There was significant difference between either of the homozygous susceptible strains and the homozygous refractory triple marker strain (calculated F-value = 28.61; critical tabular F-value = 10.92; p less than 0.01). Therefore, the % uptake efficiency of Ae. aegypti for F. candezi microfilariae is influenced by the gene (fm) which also allows the development of the filariae. - The percentage efficiency (observed/expected X 100) in abstracting microfilariae from infecting blood source by homozygous susceptible strains was about twice that (80.98%) observed for a homozygous refractory triple marker strain.

Aedes↗
PubMed1987

Exsheathment of microfilariae of Brugia pahangi in Anopheles quadrimaculatus and Culex quinquefasciatus.

In order to determine whether the exsheathment patterns described in our previous study occurred in other microfilaria-mosquito systems, exsheathment of microfilariae of Brugia pahangi was studied in two species of mosquitoes. The results of the quantitative observation revealed that the microfilariae of Brugia pahangi tend to carry their sheaths into the haemocoel of Anopheles quadrimaculatus and Culex quinquefasciatus within 4 hr after infected blood meals. The percentage of the sheathed microfilariae in the haemocoel progressively decreased to 0% at 24 hr post-ingestion. Microfilariae remaining in the midgut of both species of mosquitoes were recorded most frequently casting off their sheaths in the midgut 2 hr post-ingestion. The percentage of microfilariae exsheathed in the midgut progressively increased to about 100% and 40% 24 hr post-ingestion in Anopheles quadrimaculatus and Culex quinquefasciatus respectively. These results confirm that exsheathment of microfilariae of Brugia pahangi occurs both in the haemocoel and in the midgut of two species of mosquitoes.

Animals↗
PubMed1983

Periodicity of Dirofilaria immitis microfilariae in canine and murine hosts.

Microfilariae of Dirofilaria immitis were recovered from an experimentally infected dog and inoculated intravenously into adult female BALB/c mice. Each mouse received 1 X 10(5) microfilariae. In one experiment mice were sublethally irradiated with gamma radiation 24 h prior to microfilarial inoculation; microfilariae were counted at 11.00 and 23.00 h 7, 14, 21, 28, 35 and 42 days after inoculation. A similar experiment was performed in nonirradiated mice to ensure that sublethal irradiation had not caused microfilarial periodicity. In a third experiment microfilaria numbers were determined in sublethally irradiated mice at 4-h intervals for 48 h beginning 14 days after microfilarial inoculation; microfilaria numbers at each bleeding were compared to microfilarial density at the same time in the donor dog. In a fourth experiment 2 groups of mice were irradiated, inoculated and bled as before; one group was acclimated to light from 07.00 h to 19.00 h, whereas the other group was acclimated to light from 19.00 h to 07.00 h. The microfilaremia was subperiodic, varying regularly with time in both the dog and mice. Microfilariae in the dog reached maximum numbers during light hours. In each experiment, regardless of actual time, microfilariae in mice reached maximum numbers during dark hours.

Animals↗
PubMed1983

Development of Onchocerca volvulus from cryopreserved microfilariae in three temperate species of laboratory-reared blackflies.

Three species of British blackflies, Simulium ornatum s.l., S. erythrocephalum and S. lineatum, were infected with the cryopreserved microfilariae of Onchocerca volvulus obtained from human skin-snips in the Sudan. Doses of 5 or 10 microfilariae per fly were administered by intrathoracic injection into females, 1-2 days after eclosion from pupae. After 7 days at 27.5 degrees C and 85% relative humidity, microfilariae had completed development to third-stage larvae. Fly survival rates were highest for S. ornatum (96%) and lowest for S. lineatum (56%), and fell only marginally in each species when the larger dose of microfilariae was given. Infection rates ranged from 42% in S. lineatum up to 58% in S. ornatum following the lower dose of microfilariae, and 58% in S. lineatum up to 79% in S. ornatum following the higher dose. The proportion of microfilariae which completed development was relatively constant in each species of fly, ranging from 3.1-4.2% in S. lineatum to 10.5-16.8% in S. erythrocephalum. The greatest number of third-stage larvae recovered came from S. erythrocephalum at the higher dose of microfilariae, with a mean of 2.4 larvae per infected fly. As S. erythrocephalum has been successfully colonized through several generations in the laboratory, it is concluded that this is a promising species for reselection for increased susceptibility to O. volvulus.

Animals↗
PubMed1981

[Intake of microfilariae by the vector for a periodic filarioid, Dipetalonema dessetae (author's transl)].

The Filariid D. dessetae in its natural host, Proechimys oris, has a daily periodic microfilaraemia with a conspicuous peak during the day (blood from the ocular sinus). --If the mosquitoes engorge during the daily peak, the density of microfilariae ingested is equal or slightly superior to the density of microfilaria in the blood from the ocular sinus. However, if they engorge during the night they ingest 2,5 times the number of microfilariae than the density of microfilariae in the ocular sinus indicates they should. Thus during the night there is a phenomenon of persistence of microfilariae in the cutaneous blood circulation of the rodent. --With mosquitoes of similar size each ingesting a similar volume of blood the distribution of Aedes as a function of the number of microfilariae ingested resembles the Poisson distribution. This indicates that the distribution of microfilariae which are accessible to the vector in the blood of Proechimys is nearly homogeneous.

Aedes↗
PubMed1981

Limited fly load and development of Onchocerca volvulus microfilariae in Guatemalan Simulium ochraceum.

Fly load of Onchocerca volvulus microfilariae and their early development in Simulium ochraceum were examined at intervals of 10, 30 and 60 min after ingestion and then hourly up to 72 hours. Many microfilariae ingested were damaged by the cibarial armature of the vector, limiting the fly load, but some of these damaged microfilariae were able to penetrate the gut before they died. Thus, the mean number of the living parasites per fly in the head and thorax decreased gradually with elapse of time after ingestion. The parasites ingested by S. ochraceum did not develop beyond the microfilarial stages during the first 24 hours; thereafter only thoracic forms (1st-stage larvae) were found to be alive. The high mortality of the infected fly might be caused by the high intakes of microfilariae and also by normal and/or partly wounded microfilariae invading various organs. The number of microfilaria ingested from different biting sites were usually high in comparison with the densities observed in each site; this indicates that the microfilariae might be attracted by the biting females.

Animals↗
PubMed1980

[Natural Transition Of Endemicity Of Malayan Flariasis In Inland Korea: Pattern Of Change In Microfilaria Rate Among Inhabitants Of Yongpung (Former Yongju) Area During The Period Of The Last Seven Years]

With a purpose to find out natural transition of endemicity of Malayan filariasis in inland Korea, a survey was conducted in June 1980 in Isan-Myeon of Yongpung-Gun (former Yongju-Gun) where an epidemiological investigation had been carried out in 1973 without any control activities such as chemotherapy. Five sample villages were surveyed for microfilaremia by 20 microliter night blood examination among inhabitants and the results of the surveys conducted in 1973 and 1980 were compared to determine natural transition of the endemicity of malayan filariasis during the period of the last 7 years. 1. The current microfilaria rate among inhabitants in the 5 villages was 2.2 % on the average (male: 1.6 %, female: 2.8 %) from 370 persons examined. By village, the rates were 5.9 % (number of persons examined: 34) in Baranggol, 0 % (30) in Guitonggl, 4.2 % (72) in Alseonggol, 0 %(65) in Jangjagol and 1.8 % (169) in Saehae. 2. Extremely low microfilaria rate was noted in young age groups. By age group, no positive case was found in those age groups below 30~39 years except 10~14 age group in which 2 positives (4.4 %) were found. Two positives each were found in the respective age groups of 40~49(3.2 %), 50~59 (4.4 %) and over 60 (3.4 %). 3. In evaluation of the natural transition of the endemicity during the period of the last 7 years, the microfilaria rate turned out from 13.1 % in 1973 to 2.2 % in 1980. The difference in the microfilaria rate was 10.9 % and the natural reduction rate per year was 1.6 % on the average. 4. From the examination of 35 cases which had revealed microfilaremia 7 years ago, 85.7 %(30) of them were found to have converted to microfilaria negatives. On the other hand, from the 151 cases which had revealed no microfilaria in 1973, only 0.7 % (1) of them was found to have converted to microfilaria positive. 5. In the intensity of microfilaremia, the number of microfilaria/20 microliter blood per positive case was 11.0 in 1973 and 9.1 in 1980. The number of microfilaria/20 microliter per examinee was 1.4 in 1973 and 0.2 in 1980, thus reduced to 1/7 during the period of the 7 years. 6. The retarding endemicity of malayan filariasis in inland Korea was considered to be resulted in by the gradual increase of environmental factors in relation to ecology of vector mosquitoes, which adversely affect to the transmission of malayan filariasis. Followings are suggested to be the factors which control the transmission of the malayan filariasis in this area: 1) Inhabitants are the only natural final host of Brugia malayi infection in this area, 2) Gradual elevation of living standards of the inhabitants, 3) Gradual awakening of consciousness and behavior among inhabitants to protect themselves from mosquito biting using such as mosquito nets and insecticide sprays, 4) Preference of animal bait of vector mosquitoes, Anopheles sinensis, 5) Increase in number of domestic animals and fowls being raised in the village areas which play a major part of blood donors to vector mosquitoes, and 6) Relatively short (3~4 months) period of mosquito season in a year.

Journal Article↗