The Aedes aegypti Eradication Program

Introduction -- History -- -- How the program works -- Organization -- Field operations -- Working with the community -- -- The program thus far -- Special problems -- Research.Two years ago the Public Health Service began a program to eradicate Aedes aegypti (the yellow fever mosquito) from all the still-infested areas under United States responsibility. This mosquito is notorious as a vector of human diseases: of yellow fever, historically one of the most dreaded pestilential diseases; of dengue fever, often called "breakbone fever" because of the pain its victims suffer; and of other hemorrhagic fevers, for example, a severe new type now epidemic in the Orient and moving slowly westward. Here is the story, briefly, of why this mosquito must be eradicated, of how the eradication program works, and of what has been done thus far

Entomological handbook for Aedes aegypti eradication

"Eradication of an insect from a large geographical area is a most difficult entomological accomplishment. Moderately effective measures often suffice to reduce insect populations to an inoffensive level, but eradication requires a sharpening and enlarging of all abatement activities. Therefore the Andes aegypti eradication program requires sincere devotion to duty and the best efforts of well trained, alert workers. This handbook provides the professional worker with information about this mosquito, its identification, significant habits, and the equipment and techniques used to seek out infestations, take and preserve samples, and identify the specimens. As mosquito populations are reduced, the task of the field inspector becomes increasingly more difficult and the role of identifications becomes even more significant in verifying eradication. The able supervisory inspectors and taxonomists will not confine their studies solely to this handbook, but will seek out and study other references, and will strengthen their abilities with field observations that may disclose new knowledge significant to the Program. " - p. 1Introduction -- Distribution -- Biology and habits of Aedes aegypti -- Life cycle -- Other common mosquitoes breeding in containers -- Mosquito collection and identification -- Pictoral key to some common mosquito larvae found in artificial containers -- Key to larval mosquitoes found in receptacles -- Pictoral key to some common adult mosquitoes associated with Aedes aegypti -- Key to adults of receptacle-breeding mosquitoesHarry D. Pratt, Kent S. Littig, Milton E. Tinker."Preliminary issue, September 1966."Includes bibliographical references (p. 43)

Increasing type-1 poliovirus capsid stability by thermal selection

Poliomyelitis is a highly infectious disease caused by poliovirus (PV). It can result in paralysis and may be fatal. Integrated global immunisation programmes using live-attenuated oral (OPV) and/or inactivated PV vaccines (IPV) have systematically reduced its spread and paved the way for eradication. Immunisation will continue post-eradication to ensure against reintroduction of the disease, but there are biosafety concerns for both OPV and IPV. These could be addressed by the production and use of virus-free virus-like particle (VLP) vaccines which mimic the ‘empty' capsids (ECs) normally produced in viral infection. Although ECs are antigenically indistinguishable from mature virus particles, they are less stable and readily convert to an alternative conformation unsuitable for vaccine purposes. Stabilised ECs, expressed recombinantly as VLPs, could be ideal candidate vaccines for a polio-free world. However, although genome-free PV ECs have been expressed as VLPs in a variety of systems, their inherent antigenic instability has proved a barrier to further development. In this study, we have selected thermally-stable ECs of type-1 PV (PV-1). The ECs are antigenically stable at temperatures above the conversion temperature of wild type (wt) virion. We have identified mutations on the capsid surface and internal networks that are responsible for the EC stability. With reference to the capsid structure, we speculate on the roles of these residues in capsid stability and postulate that such stabilised VLPs could be used as novel vaccines. Importance: Poliomyelitis is a highly infectious disease caused by PV and is on the verge of eradication. There are biosafety concerns of reintroduction of the disease from current vaccines which require live virus for production. Recombinantly-expressed virus-like particles could address these inherent problems. However, the genome-free capsids (ECs) of wt PV are unstable and readily change antigenicity to a form not suitable as a vaccine. Here, we demonstrate that the ECs of type-1 PV can be stabilised by selecting heat-resistant viruses. Our data show that some capsid mutations stabilise the ECs and could be applied as candidates to synthesise stable virus-like particles (VLPs) as future genome-free poliovirus vaccines

Recommendations of the International Task Force for Disease Eradication

This report summarizes the conclusions of the International Task Force for Disease Eradication (ITFDE), a group of scientists who were convened by a secretariat at the Carter Center of Emory University six times during 1989-1992. The purpose of the ITFDE was to establish criteria and apply them systematically to evaluate the potential eradicability of other diseases in the aftermath of the Smallpox Eradication Program. The ITFDE defined eradication as \ue2\u20ac\u153reduction of the worldwide incidence of a disease to zero as a result of deliberate efforts, obviating the necessity for further control measures.\ue2\u20ac? The names of the members of the ITFDE, the criteria they developed and used, and summaries of the papers that were presented to the ITFDE by various experts are included in this report, as well as a brief history of the concept of disease eradication since the late 19th century. The ITFDE considered more than 90 diseases and reviewed 30 of these in depth, including one noninfectious disease. It concluded that six diseases--dracunculiasis, poliomyelitis, mumps, rubella, lymphatic filariasis, and cysticercosis--could probably be eradicated by using current technology. It also concluded that manifestations of seven other diseases could be \ue2\u20ac\u153eliminated,\ue2\u20ac? and it noted critical research needs that, if realized, might permit other diseases to be eradicated eventually. The successful eradication of smallpox in 1977 and the ongoing campaigns to eradicate dracunculiasis by 1995 and poliomyelitis by 2000 should ensure that eradication of selected diseases will continue to be used as a powerful tool of international public health.Introduction -- -- A Spectrum of Disease Control -- -- A Brief History of Disease Eradication -- -- Summary of the ITFDE Deliberations -- Diseases targeted for eradication -- Diseases that could potentially be eradicated -- Diseases of which some aspect could be eliminated -- Diseases that are not eradicable now -- Diseases that are not eradicable -- -- The Future -- APPENDIX 1. Diseases screened for potential eradicability by the International Task Force for Disease Eradication"December 31, 1993"--Cover.Includes bibliographical references (p. 24-25)

What clinicians who practice in countries reaching malaria elimination should be aware of: lessons learnt from recent experience in Sri Lanka

Following progressive reduction in confirmed cases of malaria from 2002 to 2007 (41,411 cases in 2002, 10,510 cases in 2003, 3,720 cases in 2004, 1,640 cases in 2005, 591 cases in 2006, and 198 cases in 2007). Sri Lanka entered the pre-elimination stage of malaria in 2008. One case of indigenous malaria and four other cases of imported malaria are highlighted here, as the only patients who presented to the Professorial Medical Unit, Colombo North Teaching Hospital, Ragama, Sri Lanka over the past eight years, in contrast to treating several patients a week about a decade ago. Therefore, at the eve of elimination of malaria from Sri Lanka, it is likely that the infection is mostly encountered among travellers who return from endemic areas, or among the military who serve in un-cleared areas of Northern Sri Lanka. They may act as potential sources of introducing malaria as until malaria eradication is carried out. These cases highlight that change in the symptomatology, forgetfulness regarding malaria as a cause of acute febrile illness and deterioration of the competency of microscopists as a consequence of the low disease incidence, which are all likely to contribute to the delay in the diagnosis. The importance regarding awareness of new malaria treatment regimens, treatment under direct observation, prompt notification of suspected or diagnosed cases of malaria and avoiding blind use of anti-malarials are among the other responsibilities expected of all clinicians who manage patients in countries reaching malaria elimination

Analysis of the dihydrofolate reductase-thymidylate synthase gene sequences in Plasmodium vivax field isolates that failed chloroquine treatment

<p>Abstract</p> <p>Background</p> <p>To use pyrimethamine as an alternative anti-malarial drug for chloroquine-resistant malaria parasites, it was necessary to determine the enzyme's genetic variation in dihydrofolate reductase-thymidylate syntase (DHFR-TS) among Korean strains.</p> <p>Methods</p> <p>Genetic variation of <it>dhfr-ts </it>genes of <it>Plasmodium vivax </it>clinical isolates from patients who did not respond to drug treatment (<it>n </it>= 11) in Korea were analysed. The genes were amplified using the polymerase chain reaction (PCR) with genomic DNA as a template.</p> <p>Results</p> <p>Sequence analysis showed that the open reading frame (ORF) of 1,857 nucleotides encoded a deduced protein of 618 amino acids (aa). Alignment with the DHFR-TS genes of other malaria parasites showed that a 231-residue DHFR domain and a 286-residue TS domain were seperated by a 101-aa linker region. This ORF shows 98.7% homology with the <it>P. vivax </it>Sal I strain (XM001615032) in the DHFR domain, 100% in the linker region and 99% in the TS domain. Comparison of the DHFR sequences from pyrimethamine-sensitive and pyrimethamine-resistant <it>P. vivax </it>isolates revealed that nine isolates belonged to the sensitive strain, whereas two isolates met the criteria for resistance. In these two isolates, the amino acid at position 117 is changed from serine to asparagine (S117N). Additionally, all Korean isolates showed a deletion mutant of THGGDN in short tandem repetitive sequences between 88 and 106 amino acid.</p> <p>Conclusions</p> <p>These results suggest that sequence variations in the DHFR-TS represent the prevalence of antifolate-resistant <it>P. vivax </it>in Korea. Two of 11 isolates have the Ser to Asn mutation in codon 117, which is the major determinant of pyrimethamine resistance in <it>P. vivax</it>. Therefore, the introduction of pyrimethamine for the treatment of chloroquine-resistant vivax malaria as alternative drug in Korea should be seriously considered.</p

Limited duration of vaccine poliovirus and other enterovirus excretion among human immunodeficiency virus infected children in Kenya

<p>Abstract</p> <p>Background</p> <p>Immunodeficient persons with persistent vaccine-related poliovirus infection may serve as a potential reservoir for reintroduction of polioviruses after wild poliovirus eradication, posing a risk of their further circulation in inadequately immunized populations.</p> <p>Methods</p> <p>To estimate the potential for vaccine-related poliovirus persistence among HIV-infected persons, we studied poliovirus excretion following vaccination among children at an orphanage in Kenya. For 12 months after national immunization days, we collected serial stool specimens from orphanage residents aged <5 years at enrollment and recorded their HIV status and demographic, clinical, immunological, and immunization data. To detect and characterize isolated polioviruses and non-polio enteroviruses (NPEV), we used viral culture, typing and intratypic differentiation of isolates by PCR, ELISA, and nucleic acid sequencing. Long-term persistence was defined as shedding for ≥ 6 months.</p> <p>Results</p> <p>Twenty-four children (15 HIV-infected, 9 HIV-uninfected) were enrolled, and 255 specimens (170 from HIV-infected, 85 from HIV-uninfected) were collected. All HIV-infected children had mildly or moderately symptomatic HIV-disease and moderate-to-severe immunosuppression. Fifteen participants shed vaccine-related polioviruses, and 22 shed NPEV at some point during the study period. Of 46 poliovirus-positive specimens, 31 were from HIV-infected, and 15 from HIV-uninfected children. No participant shed polioviruses for ≥ 6 months. Genomic sequencing of poliovirus isolates did not reveal any genetic evidence of long-term shedding. There was no long-term shedding of NPEV.</p> <p>Conclusion</p> <p>The results indicate that mildly to moderately symptomatic HIV-infected children retain the ability to clear enteroviruses, including vaccine-related poliovirus. Larger studies are needed to confirm and generalize these findings.</p

Civil conflict and sleeping sickness in Africa in general and Uganda in particular

Conflict and war have long been recognized as determinants of infectious disease risk. Re-emergence of epidemic sleeping sickness in sub-Saharan Africa since the 1970s has coincided with extensive civil conflict in affected regions. Sleeping sickness incidence has placed increasing pressure on the health resources of countries already burdened by malaria, HIV/AIDS, and tuberculosis. In areas of Sudan, the Democratic Republic of the Congo, and Angola, sleeping sickness occurs in epidemic proportions, and is the first or second greatest cause of mortality in some areas, ahead of HIV/AIDS. In Uganda, there is evidence of increasing spread and establishment of new foci in central districts. Conflict is an important determinant of sleeping sickness outbreaks, and has contributed to disease resurgence. This paper presents a review and characterization of the processes by which conflict has contributed to the occurrence of sleeping sickness in Africa. Conflict contributes to disease risk by affecting the transmission potential of sleeping sickness via economic impacts, degradation of health systems and services, internal displacement of populations, regional insecurity, and reduced access for humanitarian support. Particular focus is given to the case of sleeping sickness in south-eastern Uganda, where incidence increase is expected to continue. Disease intervention is constrained in regions with high insecurity; in these areas, political stabilization, localized deployment of health resources, increased administrative integration and national capacity are required to mitigate incidence. Conflict-related variables should be explicitly integrated into risk mapping and prioritization of targeted sleeping sickness research and mitigation initiatives

How absolute is zero? An evaluation of historical and current definitions of malaria elimination

Decisions to eliminate malaria from all or part of a country involve a complex set of factors, and this complexity is compounded by ambiguity surrounding some of the key terminology, most notably "control" and "elimination." It is impossible to forecast resource and operational requirements accurately if endpoints have not been defined clearly, yet even during the Global Malaria Eradication Program, debate raged over the precise definition of "eradication." Analogous deliberations regarding the meaning of "elimination" and "control" are basically nonexistent today despite these terms' core importance to programme planning. To advance the contemporary debate about these issues, this paper presents a historical review of commonly used terms, including control, elimination, and eradication, to help contextualize current understanding of these concepts. The review has been supported by analysis of the underlying mathematical concepts on which these definitions are based through simple branching process models that describe the proliferation of malaria cases following importation. Through this analysis, the importance of pragmatic definitions that are useful for providing malaria control and elimination programmes with a practical set of strategic milestones is emphasized, and it is argued that current conceptions of elimination in particular fail to achieve these requirements. To provide all countries with precise targets, new conceptual definitions are suggested to more precisely describe the old goals of "control" - here more exactly named "controlled low-endemic malaria" - and "elimination." Additionally, it is argued that a third state, called "controlled non-endemic malaria," is required to describe the epidemiological condition in which endemic transmission has been interrupted, but malaria resulting from onwards transmission from imported infections continues to occur at a sufficiently high level that elimination has not been achieved. Finally, guidelines are discussed for deriving the separate operational definitions and metrics that will be required to make these concepts relevant, measurable, and achievable for a particular environment