The changing picture of intestinal parasitoses in the Caribbean

The economic and public health importance of gastro-intestinal parasitoses varies enormously from country to country due to a complex interplay of organisms, the environment, the hosts involved, socio-economic conditions, and human behaviour. The major parasitoses include three roundworm species (nematodes) and three microscopic, unicellular (protozan) species. Infection with two or more species (polyparasitism) is not uncommon, and this aggregation of parasites leads to an increased morbidity and mortality. Aggregation may result from human behaviour, socio-economic conditions (level of education, water and sanitary conditions, ability to diagnose and treat infections etc.) and numerous still relatively arcane reasons, such as immunological and nutritional status and genetics (AU)

Pruritus ani: common infection and treatment

Pruritus ani is a manifestation of a wide spectrum of disease conditions. Infections form a minor aetiological fraction but include organisms from the various microbiological subdisciplines. Fungal causes of pruritus ani usually come from the normal flora, and can be diagnosed in the office, by microscopy using a mixture of potassium hydroxide and dimethyl sulfoxide. Parasites causing pruritus ani may be transmitted by direct contact, the faeco-oral or sexually. Treatment of scabies and enterobiasis should involve simultaneous treatment of family members. Articles of clothing and bed sheets must be exposed to heat. Lindane (gamma benzene hexachloride) should not be used in pregnant women and children under the age of two years to avoid potential neurotoxicity. Irrespective of the aetiology, severe pruritus ani predisposes to secondary bacterial infection (AU)

William Hillary and sprue in the Caribbean: 230 years later

Parasitic infestation as a cause of diarrhoea and malabsorption is well recognised. It may occur in heavy infestations with hookworm as reported by Sheehy in Puerto Rico and Giardia Lamblia as reported by Professor O'Donovan of Dublin. In hookworm and giardial infestations tissue invasion of the small intestine as been observed occasionally by Stronglyoides stercoralis has much greater potential in this respect. A spru-like syndrome caused by this parasite is not uncommon in the Caribbean islands, particularly in Jamaica, Trinidad and Tobago and Puerto Rico (AU)

Studies of the epidemiology of human strongyloides stercoralis infection at endemic foci in Jamaica: clustering of cases - abstract

The distribution of enteric parasites in the population is governed by a number of factors which may be both intrinsic and extrinsic in nature. While over-dispersion of intestinal helminths among indiciduals in the host population has recently attracted much interest, the spatial distribution of cases in the community has received comparatively little attention. The object of this study was to investigate the spatial distribution of cases of strongyloidiasis at Jamaican endemic foci, and to seek correlations between the presence of infection and socio-economic demographic and biomedical critieria. The home environments of 24 clinical cases of S. stercoralis infection were visited, and all the inhabitants requested to submit two consecutive stool samples for parasitological analyses. Duplicate, standard formol-ether concentration and Harada and Mori coproculture was used. Information on socio-economic isolation controls for the reference households (n=15) as well as the eleven control units (n=51). There were analysed for anti S. sterocoralis filariform IgG, using ELISA. The survey revealed at least one (and as many as three), additional case of strongyloidiasis in seven (19 percent) of the reference household; there were four instances of common infection among spouses, and an additional four among genectically related individuals in the same household. There was no parasitological evidence of infection among the inhabitants of the control units. However, serological investigations indicated no significant differences (Fisher's Exact Test) in the apparent level of exposure of individuals inhabiting the four reference households (25 percent) (index case excluded) and those occupying the control units (22 percent). Preliminary observations suggest a decline in the apparent level of exposure in the control households with increasing ambulatory distance from the reference dwelling. Presence of infection was not correlated with socio-economic index or host gender. Examination of the horizontal age-prevalence plot indicates no significant differences in infection prevalence between adults and children; the high levels of infection among the lower age groups is probably a function of the sensitvie diagnostic procedures utilized in this study. Current S. stercoralis infection appears to be familially distributed in the host community; identification of a single case of strongyloidiasis is likely to indicate the presence of a cluster of infected subclinical individuals at the same locus. Serological analyses suggest a high level of exposure to S. stercoralis in the host community, and sheds further light on the transmission of this potentially lethal parasitic infection (AU)

Ultrastructural and neuropharmacological findings in the nerve/muscle system of a digenean (Cercaria caribbea LXXI Cable)

The surface morphology and organization of the neuromuscular system in Cercaria caribbea LXXI are investigated using scanning and transmission electron microscopy, respectively. Direct and indirect (sarconeural) nerve-muscle junctions are identified in the cercarial tail. Synaptic vesicles at the direct neuromuscular junction suggest cholinergic and aminoacidergic transmission. Those at the sarconeural junctions suggest catecholaminergic and/or serotonergic transmission. Acetylcholinesterase and non-specific cholinesterases were found in high concentrations in the proximal and distal tail. Flourescence histochemistry showed primary catecholamines and 5-HT in the body and tail. 5-HT in the tail may represent a slowly depleted store, perhaps associated with energy availability and utilization. (AU)

The neurophysiological control and photosensory modulation of swimming in a cercaria, Cercaria caribbea LXXI

Scanning and transmission electron microscopy revealed that Cercaria caribbea LXXI has a small body (70 æm) with a pair of well-developed, rhabdomeric photoreceptors; and a large tail (4 mm) with six longitudinal, striated muscle bands. Muscle cells had an outer myofibrillar region adjecent to the tergument and an inner sarcoplasmic region, prolongations of which, may form sarconeural junctions. Sarcomere lengths were consistent with invertebrate fast muscle fibres. Diffuse Z-bands and the presence of numerous mitochondria are consistent with slow muscle fibres, adapted for prolonged work output. Interneuronal junctions with abundant electron-lucent and electron-dense vesicles, and neuromuscular junctions with mainly electron-lucent presynaptic vesicles were demonstrated. The neuromuscular connection between the body and tail appeared to be restricted to a single axon, implying that modulation of tail activity by the body may involve simple triggering or level setting actions, rather than complex modulation. The Falck-Hillarp Formaldehyde-Induced Fluorescence and the Gomori techniques indicated that the neuromuscular system utilizes primary catecholamines, serotonic (5-HT) and an acetylcholine-like transmitter. There were indications that 5-HT promotes activity and is held as a non-replenishable store, depleted through time within the cercarial tail. Exogenous application of a range of neuropharmacological agents, profoundly affected survivorship of the organism. Of the catecholaminergis group, propranolol (1.1-4 æM) and haloperidol (0.066-0.133 mM) most effectively reduced population half-line (T50). This was followed by the cholinergic agent, physostigmine (0.08-2.5 mM). The gamma-aminobutyric acid antagonist, picrotoxin (0.08-2.5mM), only weakly affected T50. Several drugs, especially reserpine (0.08-2.5mM), produced osmotic disturbances, leading to shortened life span. Survivorship was also dependent on pH, with a sharply defined tolerance range between pH 6 and 8. Suction electrodes recordings of electrical activity in the tail revealed spontaneous spike potentials (0.2-0.6 mV, 15-20/sec) superimposed on an underlying slow wave component. The effects of drugs on this activity were observed. 5-HT increased the amplitude and frequency of spike discharge from 0.2 mV to 0.8 mV and 15/sec to 25/sec, respectively. Physostigmine was the most effective reducer of both parameters. Indications were that cholinergic receptors in the nerve network may be excitatory nicotinic and inhibitory muscarinic. Excitatory beta adrenergic and inhibitory dopaminergic influences were observed. C. caribbea LXXI exhibited strong positive phototaxis. In response to light stimuli, the pigmented cercariae gave a maintained receptor potential with a small transient component. In the non-pigmented strain of C. caribbea LXXI, the photosensory receptor potential showed a large transient and a small maintained component. Drugs did not alter the photosensory response. A drug-induced decrease in linear translation towards a photic stimulus was therefore due to a disturbance in the neuromuscular system (AU)

Blood parasites of some Jamaican birds

The prevalence of avian hematozoa in 1791 birds of 80 species and 22 families from Jamaica was determined. Species of Haemoproteus were the most common hematozoan encountered. Species of Leucocytozoon were diagnosed only in three over-wintering North American migrants and the genus was absent in native Jamaican birds. The low prevalence of infection (7.4 percent) of blood parasites in Jamaican birds was closely similar to that seen in Neotropical birds and far below that noted for the Nearctic avifauna of the same families. Prevalence in adult and young birds was virtually identical; transmission occurred primarily during the period February to April (AU)

Some haematological investigations on infants from Kingston, Jamaica - abstract

A longitudinal study of health and growth of 270 Kingston infants was carried out from birth to 1-year of age. The infants were all born at University Hospital and were from predominantly lower socio-economic backgrounds. Haemoglobin levels were estimated 7 times during the year, mean corpuscular haemoglobin concentration 3 times, and serum iron levels and haemoglobin electro-phoresis once when the infants were 10 months old. The stool of approximately 50 percent of the infants was examined for parasites at 10 months of age. The incidence of abnormal haemoglobins was 39 (14.4 percent). 4 infants had haemoglobin SS and their health and progress is reported. Data for children with haemoglobin AS appeared to be similar to that for children with haemoglobin AA. The 33 infants with birth weights below 2.5 kgm had lower mean levels for haemoglobin, serum iron and percentage saturation of transferrin than infants with birth weigh over 2.5 kgm. The following results refer to 220 singleton infants with birth weights over 2.5 kgm. and with Hb AA or AS. The mean Hg levels from 3 months of age were lower than normal values reported from developed countries. The incidence of Hb level below 10 gms. per 100 ml. varied from 20 to 50 percent between 3 and 12 months of age. Mean values for serum irons, the percentage saturation of transferrin and the mean corpuscular haemoglobin concentration were all lower than normal and were all significantly correlated with Hb levels at 10 months of age. Several factors were examined for an association with Hb level. Hb changed with age with a steep fall from birth to 3 months of age and a slight dip at 8 months of age. Males had lower Hb levels than females. Infants with birth weights between 2.5 and 3 kgm. had lower Hb levels at 3 months of age. The prevalence of parasites was 11 percent, comprising 8 percent Giardia lamblia, 2 percent Ascaris lumbricoides and 1 percent Trichuris trichiura. No hookworm was found. Possible explanations for the high incidence of anaemia are discussed (AU)

The effect of amino acid supplementation of the host diet on the growth of the cestode hymenolepis diminuta

Although there is evidence to show that in animals on low intakes of protein the parasites flourish better than those animals on normal diets no relationship has been found between parasite growth and intake of protein. The effect of dietary protein on the growth of H. diminuta in the rat was evaluated. The animals were fed diets constant in caloric content but varying in quantity and quality of protein. Removal of casein from the diet, and its replacement by carbohydrate, resulted in a marked increase in the dry weight and nitrogen content of the parasite. Replacement of casein by fat had no effect on worm development, indicating that protein is not a significant factor. Exchange of zein for casein in the diet failed to influence parasite growth and the addition of the amino acids L-tryptophan and L-tryptophan and L-lysine to the meal containing zein in order to balance it nutritional value was also without significant effect on worm growth. These findings indicate that the growth of H. diminuta is uninfluenced by quality of dietary protein. When tryptophan and lysine were fed to the host at times other than those of giving zein, parasite growth was considerably depressed. This effect is unrelated to the quality of protein fed in the rest of the diet, since the depression in worm growth can be demonstrated by their addition to both casein and to protein free diets. Addition of these amino acids to either zein, casein or protein free diets resulted in significant changes in parasite growth, which was sometimes increased and sometimes depressed (AU)

Dermal leishmaniasis in British Honduras - the parasite

This disease is largely restricted to forest workers and is manifested by localised sores which often causes considerable disfigurement. The causative organism, Leishmania braziliensis mexiccura, is readily demonstrable in stained smears of early lesions, but this becomes increasingly difficult as the infection becomes chronic. Culture in NNN medium supplements microscopic examination. The ear is most commonly involved and lesions there tend to become chronic. Active infection may protect against re-infection but the possibility of long-term immunity is not yet classified. Infected Phlebotomine sand flies and infected rodents were found to co-exist in a selected area of forest where numerous human cases of proven leishmaniasis were found. It is suggested that the disease in British Honduras is a zoonosis. The parasites is maintained in certain rodent populations which act as intermediaries for the Phlebotomes which prey on these rodents and on man. The infected rodents found to date include the Tree-rat (Ototylomus Sp.) White-footed rat (Peromyscus Sp.) and the Spiny-ocket mouse (Heteromys Sp.) (AU)

Endoparasites of some amphibia reptiles and small mammals from Trinidad

During field studies on the virology and ecology of arboreal and terrestrial vertebrates collected from northern Trinidad during the past 10 years, animals that were killed, or those that died, were examined for endoparasites, including some haemoparasites. The main collection areas were Chaguaramas, the north coast road to Maracas, Santa Cruz Valley, the sugar cane belt in the Piarco area, Aripo Savannahs/Waller Field, Turure Forest, and Vega de Oropuche. The endoparasites identified are listed under the host animals found infected. Local and English language common names, where known, are given for the host species to assist with recognition. Data on the sites of parasite infection have been omitted from the following lists. (AU)