9. Washington, J. A. 1981. Bacteriology, clinical spectrum of disease, and thera- peutic aspects in coryneform bacterial
infections, p. 66-68. In J. S. Remington and M. N. Swartz (eds.), Current clinical topics in infectious dis-
eases, 2nd ed. MacGraw-Hill, New York.
Detection of Loa loa Microfilariae in Peritoneal Washings
Lynn M. Bernal-Green, MD Medical Director, Microbiology Laboratory Tulane Medical Center Hospital Tulane University School of Medicine, New Orleans, LA 70112
Peritoneal washings taken during pelvic surgery are routinely submitted for cytologic examination, particularly in cases in which a mass is present. Microfilariae were detected on exami- nation of bloody peritoneal washings of a patient from an endemic area.
A 26-yr-old female, a native of Cameroon, West Africa, was admitted to the gynecology service for evaluation of a pelvic mass. She subsequently underwent an exploratory laparotomy and abdominal hysterectomy. The final pathologic diagnosis was pelvic endo- metriosis.
Peritoneal washings taken at the time of surgery were processed in the cy- tology laboratory by micropore filtra- tion and stained by the Papanicolaou technique. Microscopic examination of these washings revealed numerous mi- crofilariae (Figure 1) averaging approx- imately 200 p, in length. They were sheathed, with a clearly visible cephalic space, and had anterior nuclei that were side by side (Figure 2). The sheath extended beyond the pointed tail, and the terminal nuclei were seen to extend to the tail of the organism (Figure 3). Blood subsequently taken during the day revealed numerous organisms of similar morphology on thick Giemsa- stained films.
Loiasis is caused by the filarial nem- atode Loa loa, also known as "the Af- rican eye worm." Endemic areas for this infection are the west and central African rain forests (1).
Figure 1. Microfilaria of Loa loa with demonstration of the sheath (arrow), best seen beyond the pointed tail (arrowhead). (Papanicolaou stain, magnification 400 )
Transmission in the United States has never been reported (2). The parasite is transmitted to humans in larval form by blood-feeding deer flies of the genus Chrysops.
The microfilariae inhabit capillaries of the lungs and other deep organs at night and circulate in the bloodstream during the day. In contrast to other forms of filiariasis, diagnosis is usually
Figure 2. Anterior nuclei of microfilaria are arranged side by side. Sheath beyond cephalic space is not evident in this photomicrograph. (Papanicolaou stain, magnification 1000 x )
190 0196-4399/89/$0.00 + 02.20 1989 Elsevier Science Publishing Co., Inc. Clinical Microbiology Newsletter 1 l:24,1989
Figure 3. Terminal nuclei in tail are seen at this higher magnification. Sheath (arrowhead) is seen to extend beyond the tail (arrow). (Papanicolaou stain, magnification 1000 )
through observation of the parasite in peripheral blood films taken during the day.
The infection is chronic, and it may persist asymptomatically for years. A frequent presenting symptom is con- junctival swelling, secondary to migra- tion of the adult organism beneath the bulbar conjunctiva. Prurutic swellings of the skin, known as "calabar swellings," are also seen; these are thought to be hypersensitivity reac- tions. A common finding in the pe- ripheral blood is marked eosinophilia.
Diethylcarbamazine is the treatment of choice (3). However, this treatment may result in worsening of symptoms; posttreatment encephalitis has been re- ported, although it is a rare complica- tion.
Reports of the detection of microfi- lariae in Papanicolaou-stained smears of various cytologic specimens and sources have intermittently appeared in the literature (4-6). The usual diag- nostic preparation is a thick film of pe- ripheral blood, stained with the Giemsa stain. This method does not clearly
stain the microfilarial sheath as well as does the Papanicolaou preparations. As in previous reports (4-6), this case il- lustrates the superiority of the Papani- colaou stain for identification of the morphologic features of the organism.
References 1. Connor, D. H., R. C. Neafie, and
W. M. Meyers. 1976. Loiasis, p. 356-359. In C. Binford and D. Cormor (eds.), Pathology of tropical and ex- traordinary diseases: an atlas. Armed Forces Institute of Pathology, Wash- ington, DC.
2. Ruben, F. L. et al. 1981. Loa loa among American naturalists. MMWR 30(38):479-480.
3. Abramowitz, M. (ed.), 1986. The Medical Letter 28:9-10.
4. de Brux, J. A., H. F. C. Baup, and H. Kaeding. 1983. Loa loa microfilariae in an endometrial smear. Acta Cytolo- gica 27:547-548.
5. Webber, C. A,, and L. K. Eveland. 1982. Cytologic detection of Wucheria bancrofti microfilariae in urine col- lected during a routine workup for he- maturia. Acta Cytologica 26:837-840.
6. Walker, A., H. Krishnaswami, and A. Cariappa. 1983. Microfilariae of Wu- cheria bancrofli in cytologic smears. Acta Cytologica 27:432-436.
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