Holidays in the sun and the Caribbean's forgotten burden of neglected tropical diseases

Challenges in the control of neglected insect vector diseases of human importance in the Anglo-Caribbean

INTRODUCTION

Neglected tropical diseases (NTDs) in developing countries like the Caribbean, negatively affect multiple income-generating sectors, including the tourism industry upon which island states are highly dependent. Insect-transmitted NTDs include, but are not limited to, malaria, dengue and lymphatic filariasis. Control measures for these disease, are often ignored because of the associated cost. Many of the developing country members are thus retained in a financially crippling cycle, balancing the cost of prophylactic measures with that of controlling an outbreak.The purpose of the paper is to bring awareness to NTDs transmitted by insects of importance to humans, and to assess factors affecting such control, in the English-speaking Caribbean.

METHOD

Comprehensive literature review on reports pertaining to NTDs transmitted by insects in the Caribbean and Latin America was conducted. Data search was carried out on PubMed, and WHO and PAHO websites.

RESULTS AND CONCLUSION

Potential risk factors for NTDs transmitted by arthropods in the English-speaking Caribbean are summarised. The mosquito appears to be the main insect-vector of human importance within the region of concern. Arthropod-vectors of diseases of veterinary importance are also relevant because they affect the livelihood of farmers, in highly agriculture based economies. Other NTDs may also be in circulation gauged by the presence of antibodies in Caribbean individuals. However, routine diagnostic tests for specific diseases are expensive and tests may not be conducted when diseases are not prevalent in the population. It appears that only a few English-speaking Caribbean countries have examined secondary reservoirs of pathogens or assessed the effectivity of their insect control methods. As such, disease risk assessment appears incomplete. Although continuous control is financially demanding, an integrated and multisectoral approach might help to deflect the cost. Such interventions are now being promoted by health agencies within the region and various countries are creating and exploring the use of novel tools to be incorporated in their insect-vector control programmes.

Relationships between the weaning period and the introduction of complementary foods in the transmission of gastrointestinal parasitic infections in children in Honduras

PURPOSE

This study was to investigate weaning practices used by mothers when transitioning infants from breast milk to complementary foods and to determine the role these foods have in the transmission of gastrointestinal parasites.

PARTICIPANTS AND METHODS

On average, of the 175 mothers extensively interviewed, 93% said they had breast-fed their infants. Approximately 20.8% of mothers had added some other liquid to their infant's diet at 3 months, while most mothers had added other liquids at 6 months (39.0%) and >6 months (32.1%). Some mothers expanded food offerings to infants before 3 months. The percentage of mothers who had added other liquids to their infants' diet was reported by age of the infant: as early as 1 day (2.5%), <1 week (1.9%), first month (3.1%), 3 months (20.8%), 6 months (39.0%), and >6 months (32.1%). These foods included fruit, vegetables, meat, and grains. The maximum age a child was found to be still breastfeeding was 13 years.

RESULTS

Forty percent of mothers involved in this survey reported that their children were diagnosed and/or treated for gastrointestinal parasitic infection. Routes of infection of protozoan and helminth parasites likely resulted from contaminated complementary foods and water given to infants while still breast-feeding or from contaminated foods after breast-feeding had been completed. Contaminated water is a likely source of protozoan parasites. Contaminated water was fed to infants, mixed with formula or complementary foods, or used to wash bottles for infant feeding. There was an absence of hand-washing by children and mothers before eating or while preparing foods.

CONCLUSION

The major source of soil-transmitted helminth infections was likely the result of unwashed or uncooked pureed fruit or vegetables used as complementary foods, unpasteurized animal milk, insanitary food storage, poor living conditions with exposed dirt floors, and exposure to roaming domestic animals.

High-resolution infrared thermography: a new tool to assess tungiasis-associated inflammation of the skin

BACKGROUND

Tungiasis is highly prevalent in low- and middle-income countries but remains often under diagnosed and untreated eventually leading to chronic sequels. The objective of the study was to assess whether tungiasis-associated inflammation can be detected and quantified by high-resolution infrared thermography (HRIT) and whether after removal of the parasite inflammation resolves rapidly.

METHODS

Patients with tungiasis were identified through active case finding. Clinical examination, staging, and thermal imaging as well as conventional photography were performed. In exemplary cases, the embedded sandfly was extracted and regression of inflammation was assessed by thermal imaging 4 days after extraction.

RESULTS

The median perilesional temperature was significantly higher than the median temperature of the affected foot (rho = 0.480, p = 0.003). Median perilesional temperature measured by high-resolution infrared thermography was positively associated with the degree of pain (rho = 0.395, p < 0.017) and semi-quantitative scores for acute (rho = 0.380, p < 0.022) and chronic (rho = 0.337, p < 0.044) clinical pathology. Four days after surgical extraction, inflammation and hyperthermia of the affected area regressed significantly (rho = 0.457, p = 0.005). In single cases, when clinical examination was difficult, lesions were identified through HRIT.

CONCLUSION

We proved that HRIT is a useful tool to assess tungiasis-associated morbidity as well as regression of clinical pathology after treatment. Additionally, HRIT might help to diagnose hidden and atypical manifestations of tungiasis. Our findings, although still preliminary, suggest that HRIT could be used for a range of infectious skin diseases prevalent in the tropics.

TRIAL REGISTRATION

ISRCTN11415557, Registration date: 13 July 2011.

Identification of human intestinal parasites affecting an asymptomatic peri-urban Argentinian population using multi-parallel quantitative real-time polymerase chain reaction

Background

In resource-limited countries, stool microscopy is the diagnostic test of choice for intestinal parasites (soil-transmitted helminths and/or intestinal protozoa). However, sensitivity and specificity is low. Improved diagnosis of intestinal parasites is especially important for accurate measurements of prevalence and intensity of infections in endemic areas.

Methods

The study was carried out in Orán, Argentina. A total of 99 stool samples from a local surveillance campaign were analyzed by concentration microscopy and McMaster egg counting technique compared to the analysis by multi-parallel quantitative real-time polymerase chain reaction (qPCR). This study compared the performance of qPCR assay and stool microscopy for 8 common intestinal parasites that infect humans including the helminths Ascaris lumbricoides, Ancylostoma duodenale, Necator americanus, Strongyloides stercoralis, Trichuris trichiura, and the protozoa Giardia lamblia, Cryptosporidium parvum/hominis, and Entamoeba histolytica, and investigated the prevalence of polyparasitism in an endemic area.

Results

qPCR showed higher detection rates for all parasites as compared to stool microscopy except T. trichiura. Species-specific primers and probes were able to distinguish between A. duodenale (19.1 %) and N. americanus (36.4 %) infections. There were 48.6 % of subjects co-infected with both hookworms, and a significant increase in hookworm DNA for A. duodenale versus N. americanus (119.6 fg/μL: 0.63 fg/μL, P < 0.001) respectively. qPCR outperformed microscopy by the largest margin in G. lamblia infections (63.6 % versus 8.1 %, P < 0.05). Polyparasitism was detected more often by qPCR compared to microscopy (64.7 % versus 24.2 %, P < 0.05).

Conclusions

Multi-parallel qPCR is a quantitative molecular diagnostic method for common intestinal parasites in an endemic area that has improved diagnostic accuracy compared to stool microscopy. This first time use of multi-parallel qPCR in Argentina has demonstrated the high prevalence of intestinal parasites in a peri-urban area. These results will contribute to more accurate epidemiological survey, refined treatment strategies on a public scale, and better health outcomes in endemic settings.

Prevalence of gastrointestinal parasites in children from Verón, a rural city of the Dominican Republic

Gastrointestinal infections impose a great and often silent burden of morbidity and mortality on poor populations in developing countries. The Dominican Republic (DR) is a nation on the island of Hispaniola in the Caribbean Sea. Verón is located in La Alta Grácia province in the southeastern corner of the DR. Dominican and Haitian migrant workers come to Verón to work in Punta Cana, a tourist resort area. Few definitive or comprehensive studies of the prevalence of gastrointestinal parasitic infections have been published in the DR. Historically, most of the definitive studies of water-borne or soil-transmitted parasites in the DR were published more than 30 years ago. Presently, there is a high prevalence of gastrointestinal parasitic infections throughout the poorest areas of the DR and Haiti. In this study we report the prevalence of gastrointestinal protozoan and helminth parasites from children recruited from the Clínica Rural de Verón during 2008 through 2011. Each participant was asked to provide a fecal sample which was promptly examined microscopically for protozoan and helminth parasites using the Centers for Disease Control and Prevention (CDC) fecal flotation technique to concentrate and isolate helminth ova and protozoan cysts. Of the 128 fecal samples examined, 127 were positive for one or more parasites. The age of the infected children ranged from 2–15 years; 61 were males and 66 were females. The only uninfected child was a 9 year old female. Percent infection rates were 43.8% for Ascaris lumbricoides, 8.5% for Enterobius vermicularis, 21.1% for Entamoeba histolytica, and 22.7% for Giardia duodenalis. Of the children examined, 7.8% had double infections. Any plan of action to reduce gastrointestinal parasites in children will require a determined effort between international, national, and local health authorities combined with improved education of schools, child care providers, food handlers, and agricultural workers. A special effort must be made to reach out to both documented and undocumented immigrants working or living in the area and to pre-school aged children or those who are not part of the public education system. Lastly, it is important to address the microbial water quality and food preparation, especially during the weaning transition to solid foods and throughout childhood.

Epidemiology and control of human gastrointestinal parasites in children

Parasites found in the human gastrointestinal tract can be largely categorized into two groups, protozoa and helminths. The soil-transmitted helminths (Ascaris lumbricoides, hookworm and Trichuris trichiura) are the most prevalent, infecting an estimated one-sixth of the global population. Infection rates are highest in children living in sub-Saharan Africa, followed by Asia and then Latin America and the Caribbean. The current momentum towards global drug delivery for their control is at a historical high through the efforts of numerous initiatives increasingly acting in coordination with donors, governments and local communities. Together, they have delivered enormous quantities of drugs, especially anthelmintics to children through nationwide annual or biannual mass drug administration largely coordinated through schools. However, a much larger and rapidly growing childhood population in these regions remains untreated and suffering from more than one parasite. Mass drug administration has profound potential for control but is not without considerable challenges and concerns. A principal barrier is funding. Stimulating a research and development pipeline, supporting the necessary clinical trials to refine treatment, in addition to procuring and deploying drugs (and sustaining these supply chains), requires substantial funding and resources that do not presently exist. Limited options for chemotherapy raise concerns about drug resistance developing through overuse, however, satisfactory pharmaco-epidemiology and monitoring for drug resistance requires more developed health infrastructures than are generally available. Further, the limited pharmacopeia does not include any effective second-line options if resistance emerges, and the research and development pipeline is severely depressed. Herein, we discuss the major gastrointestinal protozoa and helminths reviewing their impact on child health, changing epidemiology and how this relates to their control.

The neglected tropical diseases of Latin America and the Caribbean: a review of disease burden and distribution and a roadmap for control and elimination

The neglected tropical diseases (NTDs) represent some of the most common infections of the poorest people living in the Latin American and Caribbean region (LAC). Because they primarily afflict the disenfranchised poor as well as selected indigenous populations and people of African descent, the NTDs in LAC are largely forgotten diseases even though their collective disease burden may exceed better known conditions such as of HIV/AIDS, tuberculosis, or malaria. Based on their prevalence and healthy life years lost from disability, hookworm infection, other soil-transmitted helminth infections, and Chagas disease are the most important NTDs in LAC, followed by dengue, schistosomiasis, leishmaniasis, trachoma, leprosy, and lymphatic filariasis. On the other hand, for some important NTDs, such as leptospirosis and cysticercosis, complete disease burden estimates are not available. The NTDs in LAC geographically concentrate in 11 different sub-regions, each with a distinctive human and environmental ecology. In the coming years, schistosomiasis could be eliminated in the Caribbean and transmission of lymphatic filariasis and onchocerciasis could be eliminated in Latin America. However, the highest disease burden NTDs, such as Chagas disease, soil-transmitted helminth infections, and hookworm and schistosomiasis co-infections, may first require scale-up of existing resources or the development of new control tools in order to achieve control or elimination. Ultimately, the roadmap for the control and elimination of the more widespread NTDs will require an inter-sectoral approach that bridges public health, social services, and environmental interventions.