Ivermectin treatment of mansonellosis in Blanchisseuse, Trinidad, West Indies - abstract

The first double-blind-placebo field trial, using the drug ivermectin to control M. ozzardi microfilariae, was conducted in Blanchisseuse, North Trinidad. A preliminary trial indicated that there were no major constraints in administering the drug ivermectin within the community. In 16 patients before treatment, the microfilariae density ranged from 1 to 5,679 mf/ml, and the geometric mean was 697 mf/ml compared to 4 to 2,042 mf/ml and 362 mf/ml in the 14 patients given the placebo. Following treatment 87.5 percent (14/16) experienced side effects including fever and arthralgia (12 cases), myalgia (3 cases), headaches (11 cases) and chills (8 cases). All symptoms disappeared after 24 hours. Twenty-four hours after the ivermectin treatment the M. ozzardi microfilariae densities significantly (p < 0.001) declined to zero in 11 out of 16 cases (68.8 percent) while in 5 cases densities declined by > 95 percent. One week post-treatment there were no microfilariae observed in 93.8 percent (15/16) of cases, with one patient not attending the clinic. Blood samples collected 1 and 5 months after ivermectin treatment revealed M. ozzardi microfilariae in 3 patients. These 3 patients were re-treated with 6 mg of ivermectin, but two patients demonstrated persistent parasitaemias in subsequent blood samples. Within the placebo group, fluctuating levels of microfilariae were observed (AU)

Mass chemotherapy with diethylcarbamazine for the control of bancroftian filariasis: a 12-year follow-up in North Trinidad including observations on mansonella ozzardi microfilaraemia - abstract

A microfilaria survey was conducted in Blanchisseuse, North Trinidad in 1992 twelve years after mass treatment with spaced doses of diethylcarbamazine citrate (DEC-C) for the control of Bancroftian filariasis; 348 persons were examined, including 104 who had participated in the mass-chemotherapy campaign in 1980. No W. bancrofti microfilarie were detected among 66 percent of the population examined. In 1980, 86 persons were found with W. bancrofti, 140 with M. ozzardi and 44 with mixed infections while in 1992 only Mansonella ozzardi infections persisted despite DEC-C treatment. From the 104 persons re-examined, 46 persons had M.ozzardi, of which 5 were new cases but none had W. bancrofti infections in 1992. During both the 1980 and 1992 surveys, low microfilariae rates of M.ozzardi were observed among the 1-4, 5-9 and 10-19-year age groups. From the 302 persons examined in 1992, 29 were infected, with significantly (p<0.001) more males (79.3 percent) than females (20.7 percent) being microfilaraemic. The combined results showed similar prevalence rates of M.ozzardi from 23.3 percent to 21.6 percent in 1980 and 1992, respectively. A good correlation was found between the results observed from Nucleopore membrane filtration and thick blood films. The usefulness of thes methods and spaced treatment using DEC-C is also discussed (AU)

Filariasis in Amerindians of Western Guyana with observations on transmission of Mansonella ozzardi by a Similium species of the amazonicum group

In order to conduct experimental infection studies on Mansonella ozzardi in local haematophagos Diptera, volunteers infected with this parasite were identified during a microfilaria survey of four Amerindian villages in the Pakaraima Mountains of Western Guyana, near the Brazilian border. M. ozzardi microfilariae were detected in blood smears from 8-21 percent of persons examined. They were also found in skin snips from 8/73 persons all of whom were positive by blood smear examination. No Onchocerca volvulus microfilariae were detected. Dipetalonema perstans infections were found in three of four villages but prevalence rates were only 1-8 percent. Man-baited catches of haematophagous Diptera made at the onset of the dry season in one of the villages yielded only three Simulium species. After the flies were engorged on infected volunteers, M. ozzardi larvae developed to the infective stage in 6-7 days in the most abundant species, a member of the Simulium amazonicum group. Man-biting rates of up to 156 per 15-minute period were recorded for this species in midday collections along riverbanks near one of the villages. Developing filariae, including infective larvae of M. ozzardi, were also found in wild-caught flies. It was concluded that this Simulium species is a vector of M. ozzardi in the study area (Summary)

Dirofilaria in dogs of Surinam

Five hundred and twenty-one dogs, at least one year of age, visiting a private veterinary clinic in Paramaribo, were examined from August 1977 till August 1978. Twenty-six per cent had microfilariae of Dirofilaria immitis in their peripheral blood. The mean number per infected dog was 9.689 per ml of blood (range 14 to 78.984 per ml). Microfilaria positivity rates were significantly higher in older dogs, and there were significantly more abnormal SGPT values in positive than in negative dogs, but there were no significant associations between positivity rate and alcalic phosphatase, ureum, or creatinin values, presence of clinical symptoms, presence of antibodies to Dirofilaria immitis (measured by the direct immuno fluoroscent antibody test), sex, breed nor neighbourhood of the dogs.(AU)

Investigation of microfilarial periodicity

Clinical studies showed that Hetrazan given during the day caused an increase in blood parasite count, while exercise and administration of oxygen lead to a decrease. No significant changes were noted when vagal function was altered (AU)

Filariasis at Port Mourant and its environs Corentyne Coast, British Guiana

Report on a Filariasis survey carried out at Port Mourant Sugar Estate on the Corentyne Coast of British Guiana; 3,539 persons were examined for Micro-filariaemia and 2,815 for both M.F. and clinical manifestations of filarial disease. The over-all M.F. rate 11.2. The local epidemiology, and the relations between parasitological and clinical manifestations of filariasis, and the results of treatment by Diethyl-carbammarize, are discussed

Microfilariasis in the Turks Islands

The incidental finding of microfilariasis, possibly by Mansonella ozzardi, in two patients receiving treatment for leprosy is described. Both patients live in the same island in the Turks Islands Dependency and this is the first reported incidence of filariasis in this region. In neither patient was there any symptomatology referable to the infestation and the microfilariae were demonstrated during a routine blood examination prior to the institution of sulphone therapy for leprosy. Apart from the demonstration of the organisms and the presence of an eosinophilia, laboratory findings were not remarkable. Both patients responded well to the sulphone therapy and were discharged home to continued ambulatory treatment. No specific treatment for M. ozzardi filariasis has yet been described and, in the absence of untoward symptoms, none was attempted. The field treatment of complete populations by Hetrazan is briefly referred to. (AU)

Contribution to the geographical pathology of Surinam: 9. Acute lymphadenitis caused by Wuchereria bancrofti

The possible causes of an acute filaria attack are discussed, and case histories are given. Acute lymphadenitis is one of the clinical manifestations of the infection with W. bancrofti. In one case an acute attack occurred during treatment with hetrazan, which histopathologically must have been the result of the death of a macrofilaria. An acute filaria attack is described, which must have been due to dissemination of microfilariae; the outlet from the lymphatic gland had evidently been obstructed. However, the cause of lymphadenopathy (acute lymphadenitis) has not been explained, not even by the so-called allergic reaction