Estimated effects of climate variables on transmission of malaria, dengue and leptospirosis within Georgetown, Guyana

OBJECTIVE: To analyse meteorological data (temperature, rainfall and relative humidity) and vector-borne diseases (malaria, dengue and leptospirosis) to determine trends that may exist between and among variables within the Georgetown area. SUBJECTS AND METHODS: This study took on a retrospective approach which used data from the Ministry of Health and Ministry of Agriculture, Hydro-meteorological Department, to assess the true nature of the relationship between climate and vector-borne diseases (malaria, dengue and leptospirosis) within the Georgetown area. Correlation and regression analysis was done using SPSS version 13. RESULTS: The results yielded weak positive correlation between climate variables and vector-borne disease withstrongest correlation between P falciparum and Pmalariae. Leptospirosis showed positive correlation withhumidity and dengue showed positive correlation with all three climate variables measured. Projections showed that with a 1 increase in temperature, 1% increase in relative humidity and 50 mm increase in rainfall, there would be significant increases in malaria and leptospirosis. CONCLUSIONS: There have been theories that suggest a connection between climate variables and vector-borne disease but conclusive evidence does not exist. In this present study, the need for research that yields more unwavering results is highlighted. There is no doubt that climate variables influence vector-borne diseases. Therefore, it is recommended that an interdisciplinary approach be taken to ensure reliability and foster a better understanding between climate variables and vector-borne diseases.

Epidemiology and transmission of rotavirus infections and diarrhoea in St. Lucia, West Indies

To determine the epidemiology and risk factors of rotavirus in St. Lucia, 229 children in three valleys with varying levels of sanitation were studied for 2 years. A four-fold rise in complement fixation antibody to rotavirus antigen was used in paired samples as evidence of recent infection. Results showed that forty-eight per cent of infants experienced at least one infection during a two-year period, and 17 percent of children were reinfected. Infections occured within the first months of life and peaked between 6 and 23 months of age. The peak infection coincided with the dry season in each age group. Children breast-feeding had fewer infections. Although crowding within the home was significantly associated with repeated infection, the incidence of infection was not affected by the degree of sanitation. Other studies in the region, using recently developed techniques, concur with these findings which advance our understanding of the epidemiological importance of rotavirus in St. Lucia. Although these studies provide insights into the risk factors for rotavirus infections, other studies are required to determine whether investments should be focused on improved sanitation or immunization or both (AU)

A sero-epidemiological survey of leptospirosis among Jamaican human and animal populations

To date, relatively little research on leptospirosis has been undertaken in Jamaica and the Caribbean as a whole. This is despite the apparent role of this disease as a zoonosis. The major objective of this survey was that of determining the current status of leptospirosis in the Jamaican human, livestock and sylvatic populations through a sero-epidemiological approach. Sera for this survey were randomly selected from the ongoing National Brucelosis Control Programme serum banks at the Veterinary Diagnostic laboratory at Hope, in addition to sera collected island-wide on special field trips. Leptospiral titres were determined by the Microscopic Agglutination Test (MAT), the standard reference procedure as described by Galton et al and modified by Cole et al. All sera were tested against the following live leptopiral antigens: abramis, autumnalis, canicola, ictero-haemorrhagiae, hardjo, grippotyphhosa, jules, pomona, portland-vere, monymusk, bog-vere and pyrogenes. A presumptive positive reaction was based on a 1:100 dilution or greater to any of the test antigens used. Leptospiral determination of the approximately 12,000 sera used indicated high seroprevalence rates for all species studied. Seroprevalence rates were being reported in poultry for the first time in Jamaica. The most frequent presumptive infecting serovars found in this particular survey were portland-vere, canicola, icterohaemorrhagiae and jules. These prodominated in nearly all the species surveyed. The serovar jules is unique to Jamaica and its comparatively high prevalence in both the human and animal population indicates a necessity for further investigation. The highest yearly seroprevalence rate (46 percent) was recorded for 1986. There was no significant differences observed in sex-related seroprevalence rates for humans while age, geographical and occupational seroprevalence relationships were significant. The periods accounting for the highest precipitation had correspondingly the highest leptospiral seropositive rates. This study has confirmed that leptospirosis is both an endemic and enzootic condition in Jamaica and that the dimension of the problem may be greater than current information suggests. The results further indicate that serological surveys are useful tools and provide a pragmatic approach to the greater understanding of the epidemiological patterns of leptospirosis. An intensified national ongoing leptospirosis control programme along with an assessment of the economic impact of this disease on livestock production and its public health significance are urgently needed (AU)

Laboratory diagnosis of rotavirus infection in infantile gastroenteritis using the Elisa technique

The magnitude of gastroenteritis and its co-partner malnutrition has been amply identified in Jamaican children under five years but especially in the 6-24 month age group which are the most vulnerable. At present steps are being taken to significantly improve the existing conditions and the results have been very rewarding. Although the nutritional aspect was not emphasised in the analysis of this study it is a fact that malnutrition co-exists with gastroenteritis and the malnourished child is more prone to infection from the causative agents of gastroenteritis. Results of this show that rotaviruses are important aetiological agents of gastroenteritis in Jamaica especially in the "cooler" months of the year. The higher prevalence of rotavirus infection in Jamaican children (5 years and under) in December to March, the cooler months of the year is significant. This could suggest that temperature might play a role in the occurrence of the virus, in addition, there was a definite drop in temperature during those months. This pattern of higher prevalence in winter or cooler months is in accord with findings of other investigators worldwide (King et al, personal communication; Davidson et al; Bryden et a;; Kapikian et al; Middleton et al). From the findings in this study we can conclude that rotavirus appears to be significantly associated with Infantile Diarrhoea in Jamaican children, that there is a higher incidence in the cooler months of the year, and that there is correlation with previous studies by other investigators in different parts of the world in different aspects like clinical factors, age and sex, socio-economic status of the patients also climatological variables. Sensitivity, low cost, reagent stability, ease of procedure are some of the virtues of the ELISA. These factors are in favour of using this technique as a routine laboratory method of rotavirus detection. However, it must be remembered that optimum reproducibility is important, therefore these tests should be rigidly controlled by the inclusion of reference negative and positive antisera at all times and the specificity is further ensured by performing the Blocking Test. Although there are so many advantages in using the ELISA test routinely in a laboratory, there are also disadvantages. Among these are dependence on a foreign source for reagents and the possibility of the occurrence of false positives which calls for a blocking procedure, therefore prolonging the test results. However, the use of the ELISA technique in rotavirus detection would be beneficial to developing countries like Jamaica, if conjugate and control serum could be made available to them routinely by W.H.O. or similar health organization, or these reagents could be obtained from a reliable commercial source at a low affordable cost (Summary)

The epidemiology of infantile gastroenteritis in the Eastern Caribbean with special reference to the role of rotavirus infection

The objectives of this work were (1) to determine the relative importance of rotavirus, cytopathic viruses, selected bacteria and faecal parasites in infantile gastroenteritis in Guyana, Trinidad and St. Vincent; (2) to study the occurrence and distribution of rotavirus gastroenteritis and the clinical course of the disease; (3) to investigate transmission of faecal micro-organisms in families; (4) to assess the influence of malnutrition and respiratory disease on the course of illness; (5) to explore the role played by maternal characteristics, environment and economic status in this continuing problem; (6) to seek for rotavirus in calves in Trinidad. Human study subjects were 397 hospitalized gastroenteritis cases under three years of age. Healthy controls, registered at district health offices, were matched by age, sex and approximate home address. Data were collected from hospital records and by questionnaire. Weights were taken during hospitalization and follow-up. Stool samples were tested for viruses, bacteria and parasites. Rotavirus was detected by counterimmuno electrophoresis and ELISA with confirmation by electron microscopy. Forty-seven random family pairs were used for transmission data and samples of five-year old children were screened for rotavirus antibody. Rotavirus, the most prevalent pathogen, occurred in 21 percent of cases and one percent of controls. It was found more frequently in children 6-35 months old and not in premature newborn infants. Eighty-four percent of five-year olds had antibody. The illness was generally mild, but 5 of 30 fatal cases excreted rotavirus. Significantly increased morbidity and mortality were associated with age (<6 months), low birth weight (<2.5 kg), malnutrition (Gomez 11 or 111) and little or no breast-feeding (<1 month). Gastroenteritis cases had mothers with less education and interest in health services and fathers with more unskilled jobs and lower incomes. Case families were similar in size and structure to controls but had more diarrhoeal illness, more gastrointestinal infections and less pipe-borne water at home. Rotavirus was detected in calves with and without diarrhoea. Persistence in the environment was suspected (AU)

Dengue fever in St. Ann: a study of two outbreaks of 1969 and 1977 and their implications

This dissertation contains documentary results of the study of two outbreaks of dengue fever in the parish of St. Ann 1969 and 1977 and their implications. The study focused on four main areas: a) a comparison of the outbreaks of 1969 and 1977 to see if there were any differences in the nature and character of the disease b) a study of control programmes instituted 1969 and 1977, c) an investigation into case reporting, d) The effects of industry (AU)

Climate and painful crisis of sickle-cell disease in Jamaica

In a 10-year retrospective study a close correlation was found between low temperatures and hospital admissions for severe painful crises of sickle-cell disease.(Summary)

The role of respiratory viruses in Jamaica

This thesis describes a survey for respiratory viruses and their antibodies carried out at the Department of Microbiology, U. W. I., Mona from January, 1964 to June, 1966. The thesis is designed to show that representatives of the newer groups of viruses known to be associated with respiratory infections in humans are present in Jamaica, and to give indication of the prevalence of these viruses and their epidemiological behaviour in a tropical area. Two different approaches were made to the problem. Specimens from over 500 patients of ll ages and both sexes, suffering from both mild and severe respiratory infections were examined for the presence of respiratory viruses and their antibodies. Virus infection was detected in 67 (12.14 percent ) of these patients. Members of all the major groups of respiratory viruses, except rhinoviruses, were cultivated and serological conversions to many of them were also observed. Infections in children were found to be fairly common. Secondly, a series of surveys for antibodies to respiratory viruses in the general population were undertaken. Particular attention was paid to group A influenza viruses and their epidemic behaviour. Antibodies to type A2/Jamaica/2/63 influenza virus were widespread in the population, and there was a definite age-distribution of haemagglutination-inhibiting antibodies to certain other influenza strains. Antibodies to type C influenza virus were very common in the population of Jamaica. Antibodies to the parainfluenza viruses were also not infrequent in the sera of Jamaicans and evidence was obtained to show that these viruses and also respiratory syncytial virus caused frequent infections in infants and young children. Similarly, adenovirus antibodies were found to be acquired by the population at an early age (AU)

The age of the menarche in Jamaica

The mean age of the onset of the menarche for the patients of the Antenatal Clinic of the University Hospital of the West Indies was found to be 14.85 years, while that of the nurses at the same institution was 13.55. The mean age when both groups were combined was 14.48 years. the later menarche in the case of the patients may have been due to nutritional factors. The mean age of the menarche of the combined group was later than found in more temperate climates; this could be due to the climate and its infleunce on endocrine function and to nutrition in Jamaica (AU)

Non-specific factors in the epidemiology of yaws

Yaws is found in hot countries where the mean isotherm is in the region of 80§. It is found in humid areas which implies a heavy rainfall, a non-previous soil and luxurious vegetation. It is found in rural districts where the economic circumstances are poor, where socially the order is low and the standards of hygiene and sanitation are not high. The highest incidence of yaws infection and of active lesions, and of non-immunity, appears to be in the first two decades, after which there is a decrease within the community of the above three factors. It is probable that the main mode of infection is by contact, but flies may also have a considerable part to play in the transmission of the disease. There is a low incidence of infection in adult life, the cause of which appears to be quite distinct from a low incidence due to an acquired immunity from a previous child infection. The reason for this is not understood. However, if this assumption is correct, it would be logical to introduce some method of immunization into the mass treatment programmes. After many mass treatment the attack rates within the community are considerably reduced but there remains a small residue of relapsed, reinfected, and new cases. It has been suggested that the type of case which is responsible for the continued propagation of the disease is the latent case with relapsing ulcerative plantar framboesides. In view of the fact that yaws is infrequent or even abscent in those areas of the tropics where the economic and social status of the populace is relatively high, it is possible, that with further socio-economic progress in the so-called under developed areas, that yaws may eventually be eliminated. So may it be with many other disease (AU)

Malaria in the Leeward and Windward Islands, British West Indies

Malaria surveys under the auspices of the Colonial Development Welfare Organization (British West Indies), were made in the British units of the Leeward and Windward Islands during 1943-47. Malariometric rates of importance were recorded in Grenada, St Lucia, Dominica and Antigua where high rates were found in scattered areas. The general picture was one of localized outbreaks distributed periodically throughout each island. Splenometric findings constituted a reliable measure of recent malaria prevalence, and close positive correlation existed between degree of splenic enlargement and parasitemia. All three of the commoner Plasmodium species were present, but P. falciparum predominated; P. malariae was common, and P. vivax infrequent. Mansonella ozzardi was found in Antigua, Nevis, and St Kitts, in addition to those islands previously recorded in the literature. Four species of Anopheles were encountered-A. aquasalis, A. argyritarsis, A. albimanus and A. pseduopunctipennis. Previous records of A. albimanus in Dominica and St Vincent were not confirmed. On epidemiological data presented, both A. aquasalis and A. albimanus appeared to contribute to malaria transmission. Anticipated results in malaria control from residual DDT are briefly discussed (Summary)

The relationship of certain environmental factors to the distribution of yaws in Jamaica

A study of the history of yaws in Jamaica reveals that the disease, while it may have been present before the advent of African negroes, was repeatedly introduced by slaves, and has tended to become localized in certain parts of the island. The present distribution has been determined by inspection trips, by actual survey of 48 widely separated areas, and by questionnaire returns from 611 schools situated in every part of Jamaica. The results of the surveys and questionnaire are tabulated and will be found to agree very closely where a direct comparison is possible. The present distribution, plotted on a map, is seen to be essentially the same as it was 20 and 40 years ago, as estimated from records of the Island Medical Department. The possible relationship between certain environmental factors and this distribution is considered. These factors are rainfall, geological formation, altitude, the sanitary status of the population, urban and rural localities, and the presence of a certain insect, namely, Hippelates pallipes. A discussion considers the possible influencing effects of environment upon distribution. (Summary)