Rapid Identification of Paragonimiasis Foci by Lay Informants in Lao People's Democratic Republic

Paragonimiasis is a neglected pulmonary disease provoked by a food-borne trematode parasite. The infection may develop into severe pulmonary disease, often diagnosed with delay and confused with tuberculosis. Globally an estimated 21 millions people are infected. Human infection is acquired through consumption of raw crab, crayfish or wild boar. Typically infections occur clustered in foci of few to several villages where nutritional habits allow transmission. A major challenge for control is to identify the transmission foci. We evaluated a questionnaire approach using lay-informants at the village level to identify paragonimiasis foci and suspected cases. We sent a 4-item questionnaire to 49 village-leaders of a district in rural Lao PDR asking them to report patients with key symptoms of paragonimiasis, i.e. “chronic cough” and “blood in sputum”. The evaluation showed that lay-informants' report had a high sensitivity to identify suspected cases of paragonimiasis using “blood in sputum” as indicator. The approach allowed identifying 3 new, previously unknown foci of transmission in the district. We conclude that lay-informant questionnaires using easily identifiable key symptoms are simple to carry out and are promising low-cost tools for paragonimiasis control

Helserisiko i Laos og Thailand forbundet med lagret husholdningsvann som er forurenset fekalt og infisert med Aedes aegypti mygg

The storage of water within the household environment is commonly practiced in many countries in South-east Asia including Laos and Thailand. The practice if not properly managed, can lead to diarrhoea and dengue as a result of faecal contamination and Aedes (Ae) aegypti productions of stored water. In Laos and Thailand, diarrhoea and dengue are prevalent. However, the relationship between these diseases and household water storage remains largely obscured and therefore need to be identified for better disease prevention and control. The overall aim of this study was to determine causal factors and health risks associated with faecal contamination and Ae. aegypti infestation in household water storage in Laos and Thailand. The specific objectives were to: i) identify risk factors of Escherichia coli (E. coli) contamination and Ae. aegypti pupae infestation in household water storage containers; ii) Assess risk factors and their contribution (Proportion Attributable Fraction (PAF)) to diarrhoeal disease incidence; and iii) Assess the incidence and risk factors of dengue-like illness (DLI), and identify dengue infections. To address the study objectives, cross-sectional and longitudinal surveys were conducted in one suburban and one rural village each in Laos and Thailand. The purpose of the crosssectional survey was to gather information on the potential causal factors of E. coli contamination in stored drinking water, and Ae. aegypti infestation in domestic water containers. The longitudinal had the purposes to collect information on the incidence of DLI and diarrhoeal disease in relation to mentioned risk factors. A total of 478 households were covered in the cross-sectional survey while 2,007 individuals were enrolled in the longitudinal survey. Descriptive analysis and multi-variate regression models were used to describe the characteristics of risk factors, and to find significant relationships between the different risk factors and dengue and diarrhoea in each village. The cross-sectional survey revealed contamination of E. coli in household drinking water as well as high levels of Ae. aegypti infestation in the water storage containers in all study villages. Higher E. coli concentrations in drinking water were found in Laos than in Thailand, especially in households without toilets (in Laos) and in rural, rather than in suburban villages. The significant risk factors of E. coli contamination varied across study villages. In suburban Laos, the significant factors associated with E. coli contamination of stored water in the households were wooden house material, containers (jars and bottles), and households without toilets; whereas in rural Laos the factors were rain-fed water, containers covered with lids and households without toilets. In suburban Thailand significant factors associated with the occurrence of E. coli in drinking water were rain-fed containers, jars, buckets and container cleaning frequency; whereas in rural Thailand they were houses made of wood, manually collected rainwater and container cleaning frequency. The study revealed that E. coli contamination was less associated with socio-demographic characteristics. Regarding dengue vector production, the number of pupae collected in the study exceeded proposed dengue transmission thresholds of 0.5-1.5 pupae per person. It was shown that most of the household water storage containers in all study villages were without lids, did not contain larvicide temephos and were cleaned less frequently. Household water management and socio-demographic factors were more likely to be associated with Ae. aegypti pupae infestation. Factors that were significantly associated with Ae. aegypti infestations were tanks, less frequent cleaning of containers, containers without lids, and containers located outdoors or in toilets/bathrooms. The two-year longitudinal survey on diarrhoeal disease and dengue showed that among 2,007 individuals in the four villages, 97 diarrhoeal cases with no deaths were found comprising 35 and 11 cases in suburban and rural Laos, and 12 and 39 cases for Thai villages, respectively. The study showed that diarrhoeal incidence remains a problem for children under-five years of age, especially in suburban Laos and rural Thailand where the numbers of cases were more frequently reported. The incidences of diarrhoeal disease in under-five year old children in suburban Laos and rural Thailand were 170.5 and 180.0 episodes per 1000 person-years, respectively. The incidence reported in this study was higher than in data from the national surveillance system in both countries. In these settings, the risk factors of diarrhoea were mostly hygiene followed by socio-demographic factors. In suburban Laos, households with children under-five years of age were more likely to report a diarrhoea case (PAF: 58%), followed by households with cooking and feeding utensils left unwashed in the kitchen (PAF: 11%) and households disposing children’s stools in the open (PAF: 8%). In rural Thailand, the highest risk attributed to diarrhoea was associated with a delay in cleaning utensils (PAF: 53%). In addition to diarrhoeal disease, 83 DLI cases were recorded within the same follow up population; these included 69 in suburban Laos, 11 in rural Thailand and 3 in rural Laos (none were found in suburban Thailand). Among these 83 DLI, four (4.8%) were positive for dengue which included two cases each from suburban Laos (DENV serotype 1) and rural Thailand (DENV serotype 2). In suburban Laos, the significant risk factors of DLI were associated with household members within the age cohort of 15-20 years, people’s service occupations and the occupation group ‘other’ (retired and children). In rural Thailand, there were no significant associations between DLI and risk factors in the multivariate model. The household water storage containers have an impact not only on the microbial deterioration of drinking water, but also on production of immature Ae. aegypti. This can potentially lead to further occurrence of both dengue and diarrhoea in these settings. However, the occurrence of DLI was not significantly associated with the observed Ae. aegypti pupae per person index, even though this index was generally higher than the proposed dengue transmission threshold of 0.5-1.5 pupae per person. Based on the results in this thesis, it is recommended that stored drinking water should be treated prior to drinking in order to prevent diarrhoea in households with poor water quality. Provision of toilet facilities in Laos should be made urgently to improve quality of stored drinking water and control against diarrhoea related to improper disposal of the baby stool. Immediate cleaning of utensils after eating or cooking is also important for the reduction of diarrhoea in both Laos and Thailand. Furthermore, to achieve significant reductions in Ae. aegypti production and dengue, health education programs should be conducted on the proper use of fitted lids together with weekly cleaning of smaller water containers, as well as on proper use of larvicide temephos strictly in large water-holding containers such as tanks and jars, which were the most infested containers identified in this study. Also, adult mosquito control must also be considered in an integrated vector management strategy. Although compliance is always an issue when it comes to mosquito control, community participation will be key to the success of any selected control measure.Oppbevaring av vann i husholdninger er vanlig praksis i mange land i sør-øst Asia inkludert Laos og Thailand. Denne praksis forblir en av de største risiko faktorene for diare og dengue som et resultat av fekal forurensing og Aedes (Ae) aegypti produksjon hvis den ikke blir håndtert skikkelig. I Laos og Thailand er både diare og dengue vanlig forekommende. Sammenhengen mellom disse sykdommene og vannlagring i husholdninger er fortsatt uklar og må derfor identifiseres for å bedre prevensjon og kontroll av disse sykdommene. Hovedmålsettingen til denne PhD oppgave var å bestemme helserisiko i Laos og Thailand forbundet med lagret husholdningsvann som er forurenset fekalt og infisert med Ae. aegypti mygg. De spesifikke målsetningene var å 1) identifisere risikofaktorer til mikrobiell forurensning i lagret drikkevann, 2) identifisere risikofaktorer til infestasjon av Ae. aegypti pupper i vanntanker i husholdninger 3) vurdere risikofaktorer og deres bidrag til diareinsidens, 4) vurdere insidens og risikofaktorer denguelignende infeksjoner og å identifisere dengueinfeksjoner. For å løse studiemålene ble det gjennomført tverrsnitts- og longitudinelle undersøkelser i en forstadlandsby (suburban) og en landlig landsby (rural) hver i Laos og Thailand. Formålet med tverrsnittsundersøkelsen var å samle informasjon om de potensielle årsaksforholdene til E. coli-forurensning i lagret drikkevann og Ae. aegypti angrep i husholdningsvannbeholdere. Den longitudinelle undersøkelsen hadde til formål å samle inn informasjon om forekomsten av denguelignende og diarésykdommer i forhold til nevnte risikofaktorer. Totalt 478 husholdninger i tverrsnittsundersøkelsen og 2,007 personer ble inkludert i den longitudinelle undersøkelsen. Beskrivende analyse og multivariate regresjonsmodeller ble brukt til å beskrive karakteristikker av risikofaktorer, og til å finne viktige forhold mellom de forskjellige risikofaktorene og dengue og diare i hver landsby. Tverrsnittsundersøkelsen viste høye nivåer av E. coli forurensing i drikkevann og høye nivåer av Ae. aegypti infestasjon i vannbeholdere i mange husholdninger i alle landsbyene. Høyere E. coli konsentrasjonene i drikkevann ble funnet i Laos enn i Thailand, spesielt i husholdninger uten toalett (i Laos) og i landlige landsbyer snarere enn i forstadslandsbyer. Signifikante risikofaktorer for E. coli forurensing varierte mellom landsbyene. I forstads Laos var risiko faktorene assosiert med husmaterial av tre, beholdere (krukker og flasker) og husholdninger uten toalett; mens i landlige Laos var faktorene regn-basert vann, beholdere dekket med lokk og husholdninger uten toalett. I forstads Thailand var de betydningsfulle faktorene assosiert med E. coli i drikkevann regnvann i beholdere, krukker, bøtter og rengjøringsfrekvensen av beholdere; mens i landlige Thailand var de husmaterial av tre, manuelt innsamlet regnvann og rengjøringsfrekvensen av beholdere. Studien viste at E. coli forurensing var mindre assosiert med sosial-demografisk karakteristikker. Med tanke på dengue mygg produksjon, så var antallet myggpupper per person høyere enn foreslåtte grenseverdier på 0.5-1.5 myggpupper per person, dermed gir en høy risiko for både diare og dengue infeksjon under disse forholdene. Mesteparten av husholdningenes vannbeholdere i alle landbyene var uten lokk, hadde ingen larvicide temephos, og var rengjort sjeldnere. Håndtering av husholdningsvann og sosial-demografiske faktorer var mer sannsynlig assosiert med Ae. aegypti puppe infestasjon. Betydningsfulle faktorer som var assosiert med Ae. aegypti infestasjon var vanntanker, beholdere uten lokk og beholdere lokalisert utendørs eller i toalett/bad. Et toårs studie av diaresykdommer viste at av 2,007 individuelle personer i de fire landsbyene ble det funnet 97 diaretilfeller og ingen dødsfall. Disse inkluderer 35 tilfeller i forstads Laos, 11 i landlige Laos, 12 forstads Thailand, og 39 i landlige Thailand. Studiet viste at diare forekomster er et problem for barn under 5 år gamle, spesielt i forstads Laos og landlige Thailand hvor antall rapporterte tilfeller var høye. Forekomst av diare sykdommer blant barn under 5 år i forstads Laos og landlige Thailand var respektive 170.5 og 180.0 episoder per 1000 persondager. Disse verdiene var høyere enn data fra det nasjonale overvåkelsesystemet i begge landene. Under disse forholdene var risikofaktorene for diare for det meste assosiert med hygiene og deretter sosio-demografiske forhold. I forstads Laos var det for det meste barn under 5 år som var utsatt for diare (PAF: 58%), fulgt av de som hadde uvasket redskap på kjøkkenet (PAF: 11%) og de som kastet avføring fra barn i det åpne (PAF: 8%). I landlige Thailand var den høyeste risikoen med tanke på diare assosiert med utsettelse av vasking av redskap (PAF: 53%). I tillegg til diare sykdommer, ble det registrert 83 DLI (dengue-lignende infeksjoner) pasienter, hvor 69 var fra forstads Laos, 11 fra landlige Thailand og 3 i landlige Laos (ingen av de ble funnet i forstads Thailand). Av disse 83 DLI pasientene var 4 funnet positive for dengue (4.8%). Det inkluderer 2 tilfeller fra forstads Laos (DENV serotype 1) og landlige Thailand (DENV serotype 2). I forstads Laos, var risikofaktorene for DLI infeksjon assosiert med aldersgruppen mellom 15 og 20 år, sysselsetting (service og ‘andre’ yrkesgrupper, dvs. pensjonister og barn). I landlige Thailand var det ingen betydningsfulle assosiasjoner mellom DLI og risikofaktorer. Husholdningsvanntanker påvirker ikke bare mikrobiell forurensing av drikkevann, men også produksjon av Ae. Aegypti mygg. Dette kan potensielt føre til ytterligere forekomst av både dengue og diaré i disse områder. Imidlertid var forekomsten av DLI ikke signifikant forbundet med det observerte Ae. aegypti puppe per person, selv om denne indeksen var generelt høyere enn den foreslåtte dengueoverføringsgrensen på 0,5-1,5 pupper per person. I henhold til resultat i denne avhandling, rekommanderes at lagret drikke vann bør behandles før konsumpsjon for å forhindre diare i husholdninger med dårlig drikkevannkvalitet. Anskaffelse av forbedrede toaletter i Laos bør gjøres raskt for å forbedre kvaliteten på lagret drikkevann og kontroll av diaré relatert til feilaktig bortskaffelse av babyavføring. Umiddelbar rengjøring av redskap etter spising eller matlaging er også viktig for å redusere diaretilfeller i både Laos og Thailand. For å oppnå betydningsfull reduksjon av Ae. aegypti produksjon og dengue bør helseopplæringsprogrammer utføres på riktig bruk av lokk på vannbeholdere sammen med ukentlig rengjøring av mindre vannbeholdere, samt om riktig bruk av larviciden temephos for bruk i store vannbeholdere som tanker og krukker som var de mest infiserte beholderne i denne studien. Kontroll av voksne mygg må også vurderes i en integrert vektorkontroll strategi. Selv om overholdelse alltid er et problem når det gjelder myggkontroll, vil samfunnsdeltakelse være nøkkelen til suksess til hvilken som helst kontrollmåte

Effects of socio-demographic characteristics and household water management on Aedes aegypti production in suburban and rural villages in Laos and Thailand

publishedVersio

Dengue-like illness surveillance: a two-year longitudinal survey in suburban and rural communities in the Lao People’s Democratic Republic and in Thailand.

Objective: This study aimed to determine the incidences of dengue-like illness (DLI), dengue virus (DENV) infection, and serotypes and to identify socio-demographical and entomological risk factors of DLI in selected suburban and rural communities in the Lao People’s Democratic Republic and in Thailand. Methods: A two-year longitudinal study was conducted in four villages during the inter-epidemic period between 2011 and 2013. Entomological surveys, semi-structured interviews of household heads and observations were conducted. Occurrences of DLI were recorded weekly using the World Health Organization’s dengue definition along with blood samples; results were compared with national surveillance dengue data. Risk factors of DLI were assessed using logistic regression. Results: Among the 2007 people in the study, 83 DLI cases were reported: 69 in suburban Lao People’s Democratic Republic, 11 in rural Thailand, three in rural Lao People’s Democratic Republic and none in suburban Thailand. Four were confirmed DENV: two from suburban Lao People’s Democratic Republic (both DENV-1) and two from rural Thailand (both DENV-2). Although the number of detected DLIs during the study period was low, DLI incidence was higher in the study compared to the dengue surveillance data in both countries. DLI in suburban Lao People’s Democratic Republic was associated with age and occupation, but not with the number of pupae per person. Discussion: This study highlights the importance of continuous clinical and vector surveillance for dengue to improve early detection of dengue and other mosquito-borne diseases in the region

Dengue-like illness surveillance: a two-year longitudinal survey in suburban and rural communities in the Lao People’s Democratic Republic and in Thailand.

Objective: This study aimed to determine the incidences of dengue-like illness (DLI), dengue virus (DENV) infection, and serotypes and to identify socio-demographical and entomological risk factors of DLI in selected suburban and rural communities in the Lao People’s Democratic Republic and in Thailand. Methods: A two-year longitudinal study was conducted in four villages during the inter-epidemic period between 2011 and 2013. Entomological surveys, semi-structured interviews of household heads and observations were conducted. Occurrences of DLI were recorded weekly using the World Health Organization’s dengue definition along with blood samples; results were compared with national surveillance dengue data. Risk factors of DLI were assessed using logistic regression. Results: Among the 2007 people in the study, 83 DLI cases were reported: 69 in suburban Lao People’s Democratic Republic, 11 in rural Thailand, three in rural Lao People’s Democratic Republic and none in suburban Thailand. Four were confirmed DENV: two from suburban Lao People’s Democratic Republic (both DENV-1) and two from rural Thailand (both DENV-2). Although the number of detected DLIs during the study period was low, DLI incidence was higher in the study compared to the dengue surveillance data in both countries. DLI in suburban Lao People’s Democratic Republic was associated with age and occupation, but not with the number of pupae per person. Discussion: This study highlights the importance of continuous clinical and vector surveillance for dengue to improve early detection of dengue and other mosquito-borne diseases in the region

Dengue-like illness surveillance: a two-year longitudinal survey in suburban and rural communities in the Lao People’s Democratic Republic and in Thailand

Objective: This study aimed to determine the incidences of dengue-like illness (DLI), dengue virus (DENV) infection, and serotypes and to identify socio-demographical and entomological risk factors of DLI in selected suburban and rural communities in the Lao People’s Democratic Republic and in Thailand. Methods: A two-year longitudinal study was conducted in four villages during the inter-epidemic period between 2011 and 2013. Entomological surveys, semi-structured interviews of household heads and observations were conducted. Occurrences of DLI were recorded weekly using the World Health Organization’s dengue definition along with blood samples; results were compared with national surveillance dengue data. Risk factors of DLI were assessed using logistic regression. Results: Among the 2007 people in the study, 83 DLI cases were reported: 69 in suburban Lao People’s Democratic Republic, 11 in rural Thailand, three in rural Lao People’s Democratic Republic and none in suburban Thailand. Four were confirmed DENV: two from suburban Lao People’s Democratic Republic (both DENV-1) and two from rural Thailand (both DENV-2). Although the number of detected DLIs during the study period was low, DLI incidence was higher in the study compared to the dengue surveillance data in both countries. DLI in suburban Lao People’s Democratic Republic was associated with age and occupation, but not with the number of pupae per person. Discussion: This study highlights the importance of continuous clinical and vector surveillance for dengue to improve early detection of dengue and other mosquito-borne diseases in the region

Relationship between Aedes aegypti production and occurrence of Escherichia coli in domestic water storage containers in rural and sub-urban villages in Thailand and Laos

In a cross-sectional survey in one rural and one suburban village each in Thailand and Laos the relationship between Aedes aegypti production and Escherichia coli contamination in household water storage containers was investigated. Entomological and microbiological surveys were conducted in 250 and 239 houses in Thailand and Laos, respectively. Entomological indices across all four villages were high, indicating a high risk for dengue transmission. Significantly more Ae. aegypti pupae were produced in containers contaminated with E. coli as compared to those that were not, with the odds of Ae. aegypti infested containers being contaminated with E. coli ranging from two to five. The level of E. coli contamination varied across container classes but contamination levels were not significantly associated with the number of pupae produced. We conclude that the observed relationship between Ae. aegypti production and presence of E. coli in household water storage containers suggests a causal relationship between dengue and diarrheal disease at these sites. How this relationship can be exploited for the combined and cost-effective control of dengue and diarrheal diseases requires further research

Water, Livelihood and Health in Attapeu Province in Lao PDR

This paper presents the results of an investigation on water-borne infectious diseaseconducted among the people of Attapeu province from 2003 to 2008. Regardless of the lastcholera epidemic in Attapeu province, Lao PDR in the year 1999, the local peoples'awareness of cholera was remarkably low, as demonstrated by the knowledge survey ondiarrheal diseases performed in the province in 2006. In the case study material, derivedfrom continuous field observations on malaria among permanent residents in relocatedvillages in Sanxay district from 2004 to 2008, the infection rate among febrile cases was ashigh as 45% in the early resettlement period, while it was proved that the rate fell later to1.9-14%. Judging from the environmental condition of this settlement area, this papermakes clear the persistent threat of malaria. Furthermore, among the villagers, hookworminfection was highly prevalent. However, liver fluke infections were scarce and noascariasis was found from parasitic stool examination in 2007. Water quality analysis ofthe water sources resulted in remarkably safe water from tube wells from 2003 to 2008

Paragonimus paishuihoensis metacercariae in freshwater crabs, Potamon lipkei, in Vientiane Province, Lao PDR

Among Paragonimus species, P. paishuihoensis is one of the most mysterious and poorly understood species. Metacercariae are characterized by having a unique dendritically branched excretory bladder. However, the morphology of the adult worm remains unknown. To date, metacercariae of this species have been reported only in China and Thailand. In this study, we first found P. paishuihoensis metacercariae in freshwater crabs, Potamon lipkei, in Hinheub District, Vientiane, Lao PDR, with a prevalence of 77.7% and the average intensity of 10.3 (range 1-28) metacercariae per crab. The molecular data based on ITS2 and CO1 markers indicated that P. paishuihoensis from Laos and Thailand were almost completely identical and were close to members of the Paragonimus bangkokensis/Paragonimus harinasutai complex. Attempts to infect experimental animals (cats, dogs, and rats) with P. paishuihoensis were unsuccessful, suggesting that these animals might be unsuitable definitive hosts for the species. Further studies are necessary to elucidate the taxonomic status and life cycle of P. paishuihoensis