Microfilariae of Wuchereria bancrofti in cytologic smears

Microfilariae of Wuchereria bancrofti were observed in cytologic material in 35 cases. The material included cervicovaginal smears (17 cases), effusions (14), urine (2), bronchial washings (1) and ovarian cyst fluid (1). The initial diagnosis was made from the cytologic smear in all cases; none had clinical filariasis. Symptomatic vaginal bleeding in 9 of the 17 cases with microfilaria-positive cervicovaginal smears was reflected in the large numbers of red blood cells found in the smear. Blood eosinophilia was present in 11 of 19 cases investigated. Eosinophils were seen in the smears in 20 cases. In the majority of the cases of effusions with microfilariae the effusions were malignant. Significant adherence of inflammatory cells and macrophages to microfilariae was present in 7 of the 35 cases. The significance of these findings is discussed.     

A New Staining Technique For Microfilariae

A rapid whole mount staining method is described to identify and differentiate microfilariae without elaborate processing. A single solution combining Hoyer's mounting medium and hematoxylin stain facilitates light microscopic examination of nuclei and sheaths of microfilariae. The new technique stains microfilariae adequately in three to seven minutes at 60-64 C making the method preferable to conventional methods that may take as long as 45 to 60 minutes. Lantern heat may be used to heat slides in rural areas with good results.     

Microfilariae in fine needle aspirates from epididymal lesions

Microfilariae of Wuchereria bancrofti were observed in fine needle aspiration smears from three epididymal nodules, and degenerating microfilariae suggestive of Brugia malayi were found in the smears from a fourth case. The smears in all four cases showed a polymorphonuclear inflammatory cell component as well as epithelioid cell granulomata. While blood eosinophilia was present in all four cases, eosinophilia was present in the aspiration smears in only one case. Microfilariae could be demonstrated in the peripheral blood in only one case.     

Microfilariae infection in wild birds from the Brazilian cerrado

We report the occurrence of microfilariae in wild birds of a cerrado area in northern Brazil (Tocantins State). Analyses of 166 passerine birds belonging to 46 species and 17 families captured between 2006 and 2008 revealed that 11 individuals (6.6%) were hosts for microfilariae. Two bird species, Formicivora grisea and Formicivora rufa (Thamnophilidae), were identified as hosts for microfilariae for the first time, and had high intensities of microfilaremia (65 and 107 in 100 microscopic fields, respectively). The prevalence and intensity of microfilariae described in the present study are among the highest reported for wild bird communities in the neotropics.     

Cutaneous Distribution and Circadian Rhythm of Onchocerca lupi Microfilariae in Dogs

Background

Among the arthropod-borne nematodes infesting dogs, Onchocerca lupi (Spirurida: Onchocercidae) is of increasing zoonotic concern, with new human cases of infection diagnosed in Turkey, Tunisia, Iran and the USA. Knowledge of the biology of this nematode is meagre. This study aimed at assessing the distribution and periodicity of O. lupi microfilariae from different body regions in naturally infested dogs.

Methodology/Principal Findings

Skin samples were collected from six dogs infested with O. lupi but without apparent clinical signs. Two skin samples were collected from 18 anatomical regions of dog 1 at necropsy. In addition, single skin biopsies were performed from the forehead, inter-scapular and lumbar regions of dogs 2–6, in the morning, afternoon, and at night. Two aliquots of the sediment of each sample were microscopically observed, microfilariae counted and morphologically and molecularly identified. Most of the 1,667 microfilariae retrieved from dog 1 were in the right ear (59.6%), nose (26.5%), left ear (6.7%), forehead (3.0%), and inter-scapular (2.9%) regions. In dogs 2–6, the overall mean number of microfilariae was larger on the head (n = 122.8), followed by the inter-scapular (n = 119.0) and lumbar (n = 12.8) regions. The overall mean number of microfilariae was larger in the afternoon (153.4), followed by night (75.4) and morning (25.8).

Conclusions

Onchocerca lupi microfilariae were more common in the head (i.e., ears and nose) than in the remaining part of the dog''s body, indicating they tend to aggregate in specific body regions, which are the best sites to collect skin samples for diagnostic purposes. The periodicity pattern of microfilariae of O. lupi and their concentration in specific body regions is most likely a result of the co-evolution with their as-yet-unknown vector. The detection of skin microfilariae in asymptomatic animals, suggests the potential role of these animals as carriers and reservoirs of O. lupi.     

Microfilariae in association with neoplastic lesions: report of five cases

Microfilariae and adult filarial worms have occasionally been detected in association with neoplastic lesions in cytological smears. The presence of microfilariae along with neoplasms is generally regarded as a chance association, yet some authors suggest that such parasitic infestations may be a causative factor for tumourigenesis. There are only a few reported cases in cytology literature documenting this association. We report the presence of microfilariae in routine cytology smears from one benign and four malignant tumours. Microfilariae could not be identified on histopathology available in four of these cases.     

Microfilariae in association with other diseases. A report of six cases

BACKGROUND: Lymphatic filariasis is a major public health problem in tropical countries. Earlier reports have reported microfilariae as an incidental finding in body fluids and fine needle aspiration smears from various sites. CASES: The findings of body fluid cytology and fine needle aspiration smears from six patients with microfilariae in association with other conditions--tubercular pleural effusion/lymphadenitis, pregnancy and non-Hodgkin's lymphoma--are presented. Three patients demonstrated an associated eosinophilic cellular exudate. Adherence of inflammatory cells to microfilariae was seen in two patients. CONCLUSION: Although microfilariae in cytologic smears are considered incidental findings, the association of microfilariae with debilitating conditions suggests that it is an opportunistic infection and needs further study.     

Live Brugia malayi Microfilariae Inhibit Transendothelial Migration of Neutrophils and Monocytes

Lymphatic filariasis is a major tropical disease caused by the parasite Brugia malayi. Microfilariae (Mf) circulate in the peripheral blood for 2–3 hours in synchronisation with maximal feeding of the mosquito vector. When absent from the peripheral blood, Mf sequester in the capillaries of the lungs. Mf are therefore in close contact with vascular endothelial cells (EC) and may induce EC immune function and/or wound repair mechanisms such as angiogenesis. In this study, Mf were co-cultured with human umbilical vein EC (HUVEC) or human lung microvascular EC (HLMVEC) and the transendothelial migration of leukocyte subsets was analysed. In addition, the protein and/or mRNA expression of chemokine, cytokine and angiogenic mediators in endothelial cells in the presence of live microfilariae were measured by a combination of cDNA arrays, protein arrays, ELISA and fluorescence antibody tests.Surprisingly, our findings indicate that Mf presence partially blocked transendothelial migration of monocytes and neutrophils, but not lymphocytes. However, Mf exposure did not result in altered vascular EC expression of key mediators of the tethering stage of extravasation, such as ICAM-1, VCAM-1 and various chemokines. To further analyse the immunological function of vascular EC in the presence of Mf, we measured the mRNA and/or protein expression of a number of pro-inflammatory mediators. We found that expression levels of the mediators tested were predominantly unaltered upon B. malayi Mf exposure. In addition, a comparison of angiogenic mediators induced by intact Mf and Wolbachia-depleted Mf revealed that even intact Mf induce the expression of remarkably few angiogenic mediators in vascular EC. Our study suggests that live microfilariae are remarkably inert in their induction and/or activation of vascular cells in their immediate local environment. Overall, this work presents important insights into the immunological function of the vascular endothelium during an infection with B. malayi.     

Dipetalonema viteae: Microfilariae production in various mouse strains and in nude mice

Adult female Dipetalonema viteae worms obtained from hamsters were introduced beneath the dorsal skin of $\text{Balb}\text{c}$, $\text{C}{}_{57}\text{Bl}\text{6}$, and $\text{C}{}_3\text{H}\text{He}$ mice. The microfilaraemia from the transplanted worms in $\text{Balb}\text{c}$ mice was higher and persisted longer than in $\text{C}{}_{57}\text{Bl}\text{6}$, and in $\text{C}{}_3\text{H}\text{He}$ mice was intermediate between these two strains. The transplanted adult worms were killed earlier in $\text{C}{}_{57}\text{Bl}\text{6}$ compared to $\text{Balb}\text{c}$ mice; adult worms were killed before the microfilariae were cleared from the circulation. D. viteae infective larvae did not reach maturity in mice but when female worms were implanted into mice which had been infected with third-stage infective larvae 6 or 19 days previously, microfilarial production was inhibited. Outbred as well as inbred nude mice infected with 10 or 20 infective larvae died by Day 15, whereas the normal littermate control mice that received the same number of infective larvae remained alive and healthy. There was no difference in the duration and level of microfilaraemia from implanted female worms in outbred nudes and their heterozygous littermate control mice. In contrast, microfilaraemia in inbred $\text{Balb}\text{c}$ Nu+ was similar to that of inbred $\text{Balb}\text{c}\text{Nu}\text{Nu}$ only until Day 45; thereafter the microfilaraemia declined to zero around Day 160 in the Nu+, at which time it was still high and persisted longer in the $\text{Balb}\text{c}\text{Nu}\text{Nu}$. Transplanted adults were viable in inbred $\text{Balb}\text{c}\text{Nu}\text{Nu}$ for a longer time than in $\text{Balb}\text{c}$ Nu+. When infected, amicrofilaraemic nudes, littermate controls, and three strains of mice were challenged, a very low level short-lasting microfilaraemia resulted.     

Microfilariae in laryngeal and pharyngeal brushing smears from a case of carcinoma of the pharynx

Microfilariae were observed in May-Grünwald-Giemsa-stained brushing smears of the laryngeal and pharyngeal areas in a 35-year-old man with carcinoma of the pharyngeal wall and marked laryngeal edema. Liberation of microfilariae due to lymphorrhexis following severe lymphedema was considered to be the mechanism for the infestation of these sites, which has not been previously reported.     

Onchocerciasis: The Pre-control Association between Prevalence of Palpable Nodules and Skin Microfilariae

Background

The prospect of eliminating onchocerciasis from Africa by mass treatment with ivermectin has been rejuvenated following recent successes in foci in Mali, Nigeria and Senegal. Elimination prospects depend strongly on local transmission conditions and therefore on pre-control infection levels. Pre-control infection levels in Africa have been mapped largely by means of nodule palpation of adult males, a relatively crude method for detecting infection. We investigated how informative pre-control nodule prevalence data are for estimating the pre-control prevalence of microfilariae (mf) in the skin and discuss implications for assessing elimination prospects.

Methods and Findings

We analyzed published data on pre-control nodule prevalence in males aged ≥20 years and mf prevalence in the population aged ≥5 years from 148 African villages. A meta-analysis was performed by means of Bayesian hierarchical multivariate logistic regression, accounting for measurement error in mf and nodule prevalence, bioclimatic zones, and other geographical variation. There was a strong positive correlation between nodule prevalence in adult males and mf prevalence in the general population. In the forest-savanna mosaic area, the pattern in nodule and mf prevalence differed significantly from that in the savanna or forest areas.

Significance

We provide a tool to convert pre-control nodule prevalence in adult males to mf prevalence in the general population, allowing historical data to be interpreted in terms of elimination prospects and disease burden of onchocerciasis. Furthermore, we identified significant geographical variation in mf prevalence and nodule prevalence patterns warranting further investigation of geographical differences in transmission patterns of onchocerciasis.