Village Huts Research Articles

Comparison of deltamethrin as indoor residual spray or on insecticide treated nets for mosquito control in Lake Chilwa

We conducted a study on the control of mosquitos on Chisi Island in Lake Chilwa from August to November, 2006. The aim was to compare the cost and efficacy of deltamethrin, a pyrethroid based insecticide, when used in insecticide treated nets (ITN) and when used in indoor residual spray (IRS). Thirty village huts were enrolled in the study. Fifteen were systematically selected in a stratified manner and sprayed with deltamethrin following manufacturers' standard application procedures of 0.02g/m2. The remaining fifteen were provided with ITNs. In both groups deltamethrin KO tabs were used. Pyrethroid knockdown (PKD) spray was used for indoor rest captures in the houses monthly for three months. Houses treated with IRS had significantly reduced number of mosquitoes resting indoors than houses provided with nets (p<0.05). Based on the prevailing market price of MK550 each, the cost of five nets was calculated as MK2750.00 per house hold of five compared to five 20 g knock-out tablets costing MK300.00 using IRS. The cost of IRS is 10 times cheaper than ITN. These results suggest that it is cheaper and more effective to use deltamethrin in IRS than in ITN.

Reply to comment by Luigi Vigliotti on “Lost tsunami”

] About 8.3 ka ago a devastating tsunami flooded thecoasts of the Eastern Mediterranean Sea [Pareschi et al.,2006c]. That tsunami was triggered by a landslide from thecollapse of the eastern flanks of Mt. Etna volcano (Sicily,Italy), in turn inducing: (1) a scar on volcano slopes, namedValle del Bove, (2) inland deposits (Chiancone and Milounits), dated >7.6–8.3 ka cal B.P. [Calvari and Groppelli,1996; Calvari et al.,1998],and(3)offshorelandslidedeposits [Pareschi et al., 2006a]. The tsunami had a largeimpact, effecting southern Italy, western Greece and NorthAfrica (including Tunisia to Libya, Egypt, southern Turkey,Syria, Lebanon and Israel. In Israel the tsunami ravaged theNeolithic village of Atlit-Yam, caused the death of villagersand animals, filling a water well and destroying village huts[Pareschi et al., 2006c, 2007]. An early Holocene sea levelrise, dated 8,350–8,250 calendar year B.P., matches thetiming of the Mt. Etna tsunami, the consequent flooding ofcoastal areas led to the sudden loss of land favoured byearly farmers and initiated an abrupt expansion of activityacross Europe [Turney and Brown, 2007].[

Description of the leaf deer (Muntiacus putaoensis), a new species of muntjac from northern Myanmar

In May 1998, an expedition into northern Myanmar obtained detailed descriptive data on a new species of muntjac called the leaf deer, first discovered on a survey the previous year and characterized primarily by its diagnostic DNA compared to other muntjac species. Weights, measurements, and physical data were obtained from 12 freshly killed leaf deer, along with partial measurements from 90 head pieces of leaf deer found in village huts. Except for the diminutive, unbranched antlers on males, averaging 3.2 cm long, older male and female leaf deer were similar in size and appearance, with average weights of 12.1 kg and 11.8 kg for males and females, respectively. When compared with other species, leaf deer are one of the smallest, and perhaps one of the most primitive, extant muntjacs. Two of the most distinguishing characteristics of this new species are the relatively long, equal-sized canines in both older adult males (average 2.4 cm long) and older adult females (average 2.2 cm long), and the lack of spotting on the coats of a newborn and two juveniles estimated to be < 2 months old. All older males (n= 3) and 40% of older females (n= 5) had healed wounds on one or both ears. These wounds, in addition to the large canines in both sexes, may indicate that females as well as males compete actively for resources. Although still relatively abundant throughout mid-elevation dense evergreen forests, between the northern extremities of the Mai Kha and Mali Kha Rivers in north Myanmar, the currently known distribution of the leaf deer is outside any protected areas. Persistent hunting by local people with snares, dogs, and crossbows for a thriving market trade in deer leather, have caused noticeable decreases in numbers of leaf deer captured over recent years and could threaten the future survival of this new species.

Description of the leaf deer (Muntiacus putaoensis), a new species of muntjac from northern Myanmar

AbstractIn May 1998, an expedition into northern Myanmar obtained detailed descriptive data on a new species of muntjac called the leaf deer, first discovered on a survey the previous year and characterized primarily by its diagnostic DNA compared to other muntjac species. Weights, measurements, and physical data were obtained from 12 freshly killed leaf deer, along with partial measurements from 90 head pieces of leaf deer found in village huts. Except for the diminutive, unbranched antlers on males, averaging 3.2 cm long, older male and female leaf deer were similar in size and appearance, with average weights of 12.1 kg and 11.8 kg for males and females, respectively. When compared with other species, leaf deer are one of the smallest, and perhaps one of the most primitive, extant muntjacs. Two of the most distinguishing characteristics of this new species are the relatively long, equal‐sized canines in both older adult males (average 2.4 cm long) and older adult females (average 2.2 cm long), and the lack of spotting on the coats of a newborn and two juveniles estimated to be &lt; 2 months old. All older males (n= 3) and 40% of older females (n= 5) had healed wounds on one or both ears. These wounds, in addition to the large canines in both sexes, may indicate that females as well as males compete actively for resources. Although still relatively abundant throughout mid‐elevation dense evergreen forests, between the northern extremities of the Mai Kha and Mali Kha Rivers in north Myanmar, the currently known distribution of the leaf deer is outside any protected areas. Persistent hunting by local people with snares, dogs, and crossbows for a thriving market trade in deer leather, have caused noticeable decreases in numbers of leaf deer captured over recent years and could threaten the future survival of this new species.

Resting habits of Anopheles arabiensis in the Awash river valley of Ethiopia.

The indoor- and outdoor-resting habits of Anopheles arabiensis were studied over 2 years in central Ethiopia. Pyrethrum-spray catches and outlet-window-trap collections were carried out in both DDT-sprayed village huts and unsprayed huts. Mosquitoes were also collected from pit shelters and natural outdoor-resting sites. Females were marked and released in order to investigate their daytime-resting sites in sprayed and unsprayed huts. The An. arabiensis population in the study area is partially (37.5%) exophilic, while those females resting indoors tend to avoid DDT-sprayed surfaces and thus their contact with the insecticide is minimized.

The Case of the Socialist Witchdoctor and Other Stories

A series of stories about the oppressive regime in Ethiopia which places innocent people in the dock. Here Tuma puts the regime itself on trial, and includes other stories where life turns out to be equally full of vengeance and betrayal - in bars, brothels, guerilla hideouts and village huts.

Heightened transmission of stable malaria in an isolated population in the highlands of Irian Jaya, Indonesia.

Malaria at an elevation of 1,500 meters is uncommon and is usually unstable when it occurs. To confirm reports of a recent increase in transmission of stable malaria in the Oksibil Valley, which is at an elevation of 1,250-1,500 meters in the Jayawijaya Mountains of Irian Jaya, Indonesia, five malariometric surveys were conducted in four villages between May 1990 and July 1991. A total of 3,380 blood smears, representative of 1,949 persons, was examined. Prevalence rates over the survey period were consistent in each of the four villages, averaging 10% for infants, 50% for children 1-4 years of age, 35% for those 5-9 years old, 28% for those 10-14 years old, and 16% for adults (greater than 15 years old). The spleen rate for the those less than five years old was 96%, with an average enlarged spleen score of 2.32. Plasmodium falciparum accounted for 55% of the infections in the valley, but P. vivax was the predominant species in those less than 10 years old. In the village of Kutdol at an elevation of 1,500 meters, P. malariae was identified in 43% of the positive smears. Four cases were diagnosed as P. ovale. Infection with P. falciparum without obvious clinical symptoms was common in both adults and children. Entomologic and epidemiologic data suggested that the recent upsurge in transmission coincided with the replacement of traditional village huts with the more modern social housing. This replacement required the extensive construction of drainage ditches, which inadvertently also served as additional vector breeding sites. We suspect that this manipulation of the environment, in an effort to improve the quality of life, created conditions conductive for heightened transmission of stable malaria.

An experimental assessment of the tampan tick Ornithodoros moubata as vector of hepatitis B virus.

Wild-caught and colonized tampan ticks, Ornithodoros moubata (Murray), were fed on hepatitis B virus (HBV)-positive blood-means in a series of four experiments. Hepatitis B surface antigen (HBsAg) persisted in nymphal and adult ticks for up to 779 days, while the epsmark antigen (HBeAg) persisted in mature nymphs up to 13 days, in adult males up to 11 days and in adult females up to 16 days. HBsAg was transmitted trans-stadially through two moults during the life cycle but transovarial transmission did not occur. The surface antigen was transmitted by two out of fifteen single ticks into 0.4 ml aliquots of HBV-negative blood, although six groups of ticks failed to transmit into 5.5 ml aliquots of blood: this antigen was not transmitted to hamsters. HBsAg was detected in samples of the ticks' coxal and rectal fluid secretions always at the infecting feed and usually at the second feed. HBeAg was only detected in one of two samples of coxal fluid collected at the infecting feed. The results as a whole indicate that no biological multiplication of virus occurs in O.moubata but that mechanical transmission from ticks to man could occur by: (i) contamination of a person when crushing infected ticks; (ii) infection by bite; (iii) contamination with coxal fluid, especially by scratching bites. This is thought to take place among the Kavango tribe in their village huts in north-eastern Namibia where infestations of infected O.moubata occur.

The effectiveness of mosquito coils containing esbiothrin under laboratory and field conditions

Tests were made to correlate the chemical content of mosquito coils with the knockdown and bite-inhibitory action of the smoke in the laboratory and with the protective effect in field use. Smoke from a blank coil, containing no pyrethroid, gave no knockdown, 10% inhibition of biting in the laboratory using Aedes aegypti, and 39% protection in field tests in village huts on the Kenyan coast with a mixed population of mosquitoes including 71% Anopheles gambiae. Coils containing low experimental contents of 0.044% and 0.099% Esbiothrin, an isomer blend rich in the D-allethrolone ester of D-trans-chrysanthemic acid, gave rapid knockdown in both small chamber and 25 m3 room tests, and 71% and 94% inhibition of biting respectively in the laboratory. In the field they gave 74% and 84% protection from mosquitoes alighting. Chemical content was therefore a good guide to knockdown and bite inhibition in the laboratory and also to the considerable protection found in the field.

GENETIC DISTINCTNESS OF SYMPATRIC FORMS OF AEDES AEGYPTI IN EAST AFRICA.

Aedes aegypti is a complex species in the sense that morphological, physiological, and behavioral variation is greater than that encountered in most insect species (see e.g. Machado-Allison and Craig, 1972; McClelland, 1974; Trpis and Hausermann, 1975). In the Rabai District near Mombasa, Kenya, a particularly interesting evolutionary situation exists: two (or three) morphologically and behaviorally distinct forms of A. aegypti are sympatric. There is a light colored indoor (domestic) form which breeds in water pots customarily kept inside village huts. In forests adjacent to villages, a dark outdoor (sylvan) form of A. aegypti breeds in tree holes. Some authors (Trpis and Hausermann, 1975) recognize a third intermediate form (peridomestic) which breeds in disturbed areas such as coconut groves. Our previous publication (Tabachnick and Powell, 1978) was concerned with the population genetic structure of the indoor breeding form within and between villages. We showed that each village population is essentially a panmictic unit and that village populations separated by 1 km or less could show significant gene frequency differences. Gene frequencies were found to be stable for at least a year. This report is concerned with quantifying the genetic differences between the outdoor and indoor forms of A. aegypti in this area of Kenya. Of particular interest is the question, If these forms are sympatric and remain genetically distinct, should they be recognized as separate species?

A survey of Anopheles gambiae (species A) and An. arabiensis (species B) of the An. gambiae Giles complex in the Kisumu area of Kenya following insecticidal spraying with OMS-43 (Fenitrothion).

After village huts in the Kisumu area of Kenya had been sprayed with a nominal 2 g/m2 of OMS-43 (fenitrothion) as part of an insecticidal evaluation programme 964 adults of the Anopheles gambiae complex collected from huts were identified cytogenetically as either An. gambiae (species A) or An. arabiensis (species B). Similarly, cytogenetic methods were used to identify 349 adults collected from granaries and artificial pit-shelters. In addition, 2203 larvae of the gambiae complex collected from different types of habitats were specifically identified cytogenetically. As in a previous survey made prior to insecticidal spraying, adults of An. arabiensis predominated in outdoor collections while An. gambiae was highly endophilic. However, it appeared that spraying with fenitrothion had resulted in an increase in both the degree of exophily in An. arabiensis and also its relative numbers in respect to An. gambiae, although the overall pooulation of both species was greatly reduced by spraying. Insecticidal spraying may have diverted both species from feeding on man to cattle. Except for one village, where larvae of An. arabiensis were commoner than expected in cattle hoof-prints, there was little difference between the selection of different types of larval habitats by the two sibling species. Chromosomal inversions were more common in adults of An. arabiensis than in An. gambiae.

Ecological notes on species A and B of the Anopheles gambiae complex in the Kisumu area of Kenya

During November and December 1969, larvae and adults of the Anopheles gambiae complex from the Kisumu area of Kenya were identified by cytogenetical methods as species A and B. There appeared to be no difference between their choice of larval habitats. Although adults of both species were common in village huts, species B comprised 80·6% of the exophilic population. Adults of both species caught from huts and out of doors had fed predominantly on bovids; the incidence of human feeds was below 40%. The impact of residual insecticidal house-spraying would depend on the relative sizes of the endophilic and exophilic populations of species B.

Leishmaniasis in the Sudan Republic

Leishmaniasis in the Sudan Republic

Trials with dichlorvos (DDVP) against malaia vectors in huts in Northern Nigeria

The present investigations were undertaken because of the paucity of information on the effect of dichlorvos (2,2-dichlorvinyl dimethyl phosphate) on malaria vectors in village huts in the savannah areas of nigeria and West Africa. The relative efficiencies of 3 different makes of dichlorvos dispensers were compared by bio-assays with blood-fed Aedes (Stegomyia) aegypti (L) in village huts in the Kaduna area of Nigeria. A bio-assay mortality of 70% and over was achieved for the first 9–11 weeks. Field trials conducted with Shell dispensers on normal populations of Anopheles gambiae Giles and A. funestus Giles showed that dichlorvos was strongly repellent to both species, resulting in greatly decreased numbers of vectors in the huts. There was little irritant effect of dichlorvos on mosquitoes inside the huts, as there was little increase in either the numbers of vectors, or in their infed individuals, that left the huts. There was no reduction in the number of vectors resting under the outside eaves of dichlorvos huts and no decrease in feeding in the huts, although fewer bites per man were received in them because of a reduction in the numbers entering them. Mortalities of A. gambiae and A. funestus from dichlorvos huts were low, and it appeared unlikely that the insecticide would achieve any measure of control over malaria vectors in Northern Nigeria.

A HIGH INCIDENCE OF DIELDRIN-RESISTANCE IN ANOPHELES GAMBIAE GILES FROM AN UNSPRAYED AREA IN NORTHERN NIGERIA.

IN the course of recent investigations in the northern Guinea savannah of Nigeria on the ecology1 of Anopheles gambiae Giles and A. funestus Giles and on their behaviour in huts sprayed with insecticides2, determinations were made of the susceptibility of both species to DDT and to dieldrin in a area near the town of Kaduna. Apart from very small-scale trials in which a total of 8 village huts were sprayed with DDT and a mixture of DDT and malathion, and apart from the fairly regular use of DDT (but not dieldrin or BHC) as a larvicide on streams in the township of Kaduna, the whole of the northern Guinea savannah can be considered an unsprayed area. The nearest area receiving regular insecticidal house-spraying is the Western Sokoto area, about 200 miles north-west, where DDT has been used since 1957. Prior to this both BHC and dieldrin had been used and dieldrin-resistance in A. gambiae shown to be prevalent from 19553. Dieldrin-resistance was also found in A. gambiae in 19564 in the township of Kano, some 150 miles north-east of Kaduna, and was attributed to the use of BHC mainly for agricultural purposes.

An analysis of the numbers of Anopheles gambiae Giles and A. Funestus Giles (Diptera, Culicidae) in huts in Northern Nigeria

Pyrethrum spray-sheet collections in a small village in Northern Nigeria showed that there was no significant difference in the numbers of Anopheles gambiae Giles and A. funestus Giles caught at different times in the early morning. In this village, huts at the edge nearest to the only breeding site attracted considerably more adults than those further away from the edge, and some huts were consistently more attractive to mosquitos than others. There was a positive correlation between the numbers of A. gambiae and A. funestus in the huts. Although significant differences were found between numbers of mosquitos caught in the huts occupied by different numbers of people, no simple relationship could be discovered between the combined densities of the two species and the number of hut occupants. It is concluded that there is need for further investigations into the factors influencing densities of the Anophelines in village huts.

The ecology of the mosquitos of the Northern Guinea Savannah of Nigeria

The ecology of the mosquitos of the Northern Guinea Savannah of Nigeria

Insect Control in Public Health

preface states that this book is a follow-up of small Handbook of Malaria Control written 1940 by R. Svensson. authors of present beautifully prepared volume are wellknown workers problems related to insect transmission of human diseases. material is well organized and indexed. A full quarter of text is devoted to nine appendixes describing a series of technics developed for modern use of insecticides. This reviewer is highly conscious of difficulty of covering broad field indicated title. He feels that strictly technical parts of this volume are excellent, but that over-all public health aspects have not been adequately presented. statement that the basic principles of malaria control dealt with that booklet (Handbook of Malaria Control) have not changed represents attitude of authors toward public health aspects of their problem. It is obvious that basic principles of malaria control have been radically altered during past 25 years. 1940, prevention of malaria was limited largely to certain urban, suburban, and village areas, based essentially on reduction over-all incidence of anopheline mosquitoes brought about by larvicides. There was at that time no economically feasible method for prevention of rural malaria throughout most of world. introduction of DDT and other residual insecticides has brought attack against malaria into home with result that, for first time, public health workers are able to think terms of prevention of malaria rural areas. Although under certain special conditions residual insecticide does result a considerable reduction of anopheline mosquitoes, this is not necessarily so. residual insecticide campaign is directed not against a mosquito as such, but against mosquito which feeds human habitations and becomes infected with malaria parasites. 1940, partial malaria control most accessible populations was objective of antimalaria measures; whereas 1962, World Health Organization spearheaded a campaign for eradication of malaria throughout world. introduction it is stated that In East Africa . . . residual spraying of village huts with DDT for control of malaria also exterminated Aedes aegypti, and in parts of Central and South America where yellow fever control by anti-larval measures had been operation for some years, house spraying with DDT, added to these measures, has reduced Aedes aegypti almost to point of extinction. As a matter of fact, eradication of aegypti has been program some South American countries since 1930's, and since 1947 there has been an official Pan American Health Organization program for eradication of Aedes aegypti throughout Western Hemisphere. This program antedates introduction of DDT. Since its introduction, DDT has been used very largely as a larvicide and as a perifocal spray, and except Mexico has not been used as a house spray for eradication of aegypti. section on yellow fever, statement The disease is usually trans-