Haiti: absence of dengue hemorrhagic fever despite hyperendemic dengue virus transmission.

In 1994-1996, 185 strains of dengue (DEN) virus types 1, 2, and 4 were recovered from febrile United States and other United Nations military personnel in Haiti. We wondered whether risk factors for dengue hemorrhagic fever (DHF) existed and, if so, were DHF cases occurring among Haitian children. Dengue transmission rates were studied in 210 school children (6-13 years old) resident in Carrefour Borough, Port-au-Prince, Haiti. When sera were tested for plaque-reduction neutralizing antibodies to DEN 1-4 viruses, nearly 85% had antibodies to two or more DEN serotypes. The annual transmission rate was estimated at 30%, a rate observed in countries endemic for DHE Haitian DEN 2 isolates were genotype I, which are repeatedly associated with DHF cases in Southeast Asia and American regions. Despite positive virologic pre-conditions, DHF cases were not recorded by experienced Port-au-Prince pediatricians. These observations, which are reminiscent of those in Africa, provide further evidence of a dengue resistance gene in black populations.

A community-based trial for the control of lymphatic filariasis and iodine deficiency using salt fortified with diethylcarbamazine and iodine.

To evaluate the effectiveness of salt fortified with diethylcarbamazine (DEC) and iodine for elimination of Bancroftian filariasis and iodine deficiency, all consenting residents of Miton, Haiti (n = 1,932) were given salt fortified with 0.25% diethylcarbamazine and 25 ppm of iodine for one year. Wuchereria bancrofti microfilaria prevalence and intensity, antigenemia, and urinary iodine were measured before and one year after salt distribution began. To measure the effect of DEC-fortified salt on adult worm motility, 15 microfilaria-positive men were examined by ultrasound of the scrotal area. Entomologic surveys were conducted to determine the proportion of W. bancrofti-infected Culex quinquefasciatus. After one year of treatment, the prevalence and intensity of microfilaremia were both reduced by more than 95%, while antigenemia levels were reduced by 60%. The motility of adult worms, as detected by ultrasound, was decreased, but not significantly, by DEC-fortified salt. The proportion of vector mosquitoes carrying infective stage larvae decreased significantly from 2.3% in the nine months before the intervention to 0.2% in the last three-month follow-up period. Iodine deficiency, which had been moderate to severe, was eliminated after one year of iodized salt consumption. The DEC-fortified salt was well accepted by the community and reduced microfilaremia and transmission to low levels in the absence of reported side effects. Based on these results, salt cofortified with DEC and iodine should be considered as a concurrent intervention for lymphatic filariasis and iodine deficiency elimination programs.

Randomised placebo-controlled comparison of ivermectin and albendazole alone and in combination for Wuchereria bancrofti microfilaraemia in Haitian children.

BACKGROUND: Lymphatic filariasis and intestinal helminth infections are important disorders in tropical areas. Periodic treatment with albendazole is now used in many school-based intestinal helminth-control programmes. However, few such programmes exist for lymphatic filariasis, despite evidence that single-dose treatment with ivermectin can greatly reduce the concentration of Wuchereria bancrofti microfilariae in the blood for months to years. We aimed to assess the potential for school-based control of lymphatic filariasis by investigating the efficacy and tolerability or combined ivermectin and albendazole in Haitian schoolchildren. METHODS: In January, 1996, we collected 832 20 microL capillary blood samples for inclusion in a randomised controlled study from children aged 5-11 years, and examined them by microscopy for W bancrofti microfilariae. Infected children were randomly assigned treatment with placebo (n = 29), a single 200-400 micrograms/kg dose of ivermectin (mean, 273 micrograms/kg, n = 28), 400 mg albendazole (n = 29), or a combination of 200-400 micrograms/kg ivermectin and 400 mg albendazole (n = 24). Children with high concentrations of microfilariae in the blood were admitted to hospital and adverse reactions were monitored for 3-5 days, otherwise children were examined at school or during a visit to their home. 4 months after treatment, we examined blood samples again for microfilariae. FINDINGS: 113 microfilaraemic children were enrolled (mean age 7.8 years). 4 months after treatment, the proportion of children who remained positive for microfilariae was significantly lower in the ivermectin plus albendazole group (four [17%]), but there were no significant changes in the other three groups (20 [69%] placebo, 22 [76%] albendazole alone, 17 [61%] ivermectin alone remained positive; p = 0.004). Geometric mean microfilarial concentration decreased from 9.3 to 5.3 per 20 microL blood among children who received placebo; from 15.5 to 1.5 per 20 microL blood among those who received ivermectin only (p = 0.032); from 14.1 to 5.1 per 20 microL blood among those who received albendazole alone; and from 13.7 to 0.3 per 20 microL blood among those who received both ivermectin and albendazole (p = 0.0001). Systemic adverse reactions did not differ significantly between children who received ivermectin alone and those who were treated with ivermectin and albendazole [corrected]. INTERPRETATION: For children with W bancrofti microfilaraemia, combined treatment with ivermectin and albendazole was more effective than treatment with ivermectin only, with no measurable increase in severity of adverse reactions.