The relative importance of rotavirus and other pathogens in the etiology of gastroenteritis in Trinidadian children.

Over a 2-year period, 300 infants less than 3 years old with gastroenteritis admitted to hospitals in Trinidad were investigated for the presence of certain microorganisms in the feces, along with an equal number of age- and sex-matched controls. Rotavirus was detected in 23% of cases and 1% of controls; Salmonella in 7% of cases and in 1% of controls; Shigella in 4% of cases and in no controls and two serotypes of enteropathogenic E. coli in 7% of cases and in 2% of controls. Campylobacter fetus subspecies jejuni was cultured from 7 out of 60 cases and from 1 of 60 controls. Enterotoxigenic E. coli, most strains of enteropathogenic E. coli, cytopathic enteroviruses and adenoviruses and fecal parasites were not significantly associated with diarrhea. Rotaviruses were detected throughout the year but were more prevalent in the dry than in the rainy season. They were found less often in children younger than 6 months than in those aged 6 to 35 months and were present in 6 of the 20 children who died.

Bancroftian filariasis in coastal north Trinidad: the effects of mass chemotherapy using spaced doses of diethylcarbamazine citrate on human microfilaraemias and vector infection rates.

The effects of a mass chemotherapy programme using spaced doses of diethylcarbamazine citrate on Wuchereria bancrofti microfilaraemias and vector infection rates were studied in an isolated rural community of 650 people in north Trinidad where a microfilaria rate of 15% had previously been recorded. A single oral dose of 6 mg/kg body weight was given at monthly intervals for one year. After 6 months, 79% (52/66) of persons previously microfilaraemic had become negative. After 12 months the negative proportion had increased to 90% (63/70). The geometric mean microfilaria density of those still microfilaraemic was reduced from 19.7 to 4.6 per 100 mm3 of blood. Of 147 initially negative persons, none had become positive following treatment. Filarial infection rates in Culex quinquefasciatus from randomly sampled houses fell from 6.4% to zero; in houses where occupants with microfilaraemia had been identified before treatment, the rate was reduced from 15.8% to zero. In a supplementary study, however, weekly collections from one initially positive house showed a rapid decline in the vector infection rate from 43% to 2% after three months but an additional 3 months elapsed before the index reached zero. There was negligible microfilarial uptake by the vectors from residual low-density microfilaraemias (less than 10 microfilariae per 100 mm3 of blood) after chemotherapy.

The prevalence and distribution of Mansonella ozzardi in coastal north Trinidad, W.I.

A day blood smear survey for Mansonella ozzardi in the north coast communities of Trinidad recorded a prevalence of 4.8% in 4,488 persons examined. Prevalence rates were highest in the four western-most communities, where the vector, Culicoides phlebotomus, is a severe nuisance problem. Prevalence rates increased with age and were higher in males than in females. Mean microfilaria densities were low in both sexes up to 50 years of age but in older males the density increased with age. Wuchereria bancrofti infections were detected in five of the ten communities surveyed.

Avian pox in birds from Trinidad.

Over a 7-year period in Trinidad, 9,514 birds were examined for avian pox and four species were found infected: the golden-headed manakin, Pipra erythrocephala (7% infected), the white-bearded manakin, Manacus manacus (5%), the violaceous euphonia Euphonia violacea (1%), and the bare-eyed thrush, Turdus nudigenis (less than 1%). The elaborate courtship displays of manakins may have a bearing on a "common source" type of infection. The apparently abrupt appearance of the disease at three localities in Trinidad in 1964 perhaps indicates introduction of the virus by migratory birds.

Laboratory colonization and maintenance of Toxorhynchites moctezuma.

A colony of Toxorhynchites moctezuma was established at the Caribbean Epidemiology Centre in Trinidad in 1984. Toxorhynchites moctezuma was maintained in cages with high humidities. Eggs were deposited most frequently in a cut bicycle tire containing water. A minimum of 42 h was required for hatching, but 94% hatched between 43 and 51 h. Aedes aegypti larvae were supplied as prey. Larval development times varied with the quantity of prey offered, but when fed ad lib, peak developmental time was 18 days. Mean pupal developmental time was 5.5 days. Although only 12% of larvae survived to pupation in 3 years of production, our experience indicates this species would be a likely candidate for mass production and release.

Blastocystis hominis in two children of one family.

Two apparently healthy children from the same family were found to have moderate to heavy Blastocystis hominis in their stool samples whilst being investigated for intestinal symptoms: sporadic, painless, rectal bleeding in one and persistent diarrhoea in the other. After treatment with metronidazole, they had no further signs, and stool samples became negative. Eighteen months later, both were asymptomatic, and stool samples continued to be negative for the parasite.

Parasitological and clinical studies of Wuchereria bancrofti and Mansonella ozzardi in coastal north Trinidad, West Indies.

PIP: A parasitological and clinical survey of Wuchereria bancrofti and Mansonella ozzardi was conducted in Blanchisseuse, an isolated rural community of 650 people in coastal north Trinidad. W. bancrofti microfilariae were found in 15% of the resident population and the prevalence was higher in males (19%) than in females (12%). Microfilaraemias were undetected in children under 5 years of age but 12% of children and adolescents between 5 and 19 years of age were positive. Microfilaraemias were most common in males aged 40-59 years (34%) and in females in the same age group (21%). Whereas geometric mean microfilaria densities were generally higher in females than in males under 40 years old, in the older age groups the pattern was reversed, the difference being especially pronounced in the over 60s. There were more than 2 times as many males with M. ozzardi microfilariae (35%) than there were females (15%). The prevalence was low in children and young adults but increased with age thereafter. In the older age groups microfilaria densities followed a similar trend. Genital signs compatible with lymphatic filarial disease were seen in 29% of males; these included hydrocoele (15%) and elephantiasis of the scrotum (1%). Most signs were seen in persons over 50 years of age. 6% of females had lymphoedema of the leg(s), and in 4 cases (2.3%) this had progressed to elephantiasis. A positive association was found between M. ozzardi microfilaraemia and clinical history of articular pain. The findings suggest that both filarial species are of some public health significance in at least 1 rural area of Trinidad, and they provide a basis for the development of a lymphatic filariasis control strategy in the community.^ieng

Significant changes in gastrointestinal tract parasitic infections in children of St. Kitts over the 9-year period 1982-1991.

When 239 (1982) and 361 (1991) five- and nine-year-old children in St. Kitts were assessed for the presence of parasitic infections, there were significant reductions in the prevalence of trichuriasis from 83% to 58%, of ascariasis from 24% to 8.6% and of giardiasis from 15% to 9.4%. Anthelminthic use, which appeared to be the most important responsible intervention tool, remained roughly at the same level at 59-51%. However, the types of anthelminthics used changed over the period. Piperazine citrate, which was used by 66% in 1982, only had 35% usage in 1991. Albendazole which was not used at all in 1982 was taken by 32% of the children in 1991 and at the same time use of laevo-tetramisole increased by 20% from 14%. Suggestions are made for an island-wide mass intervention programme to manage parasitic infections.