Epidemiological Observation of Cholera in Rural Kenya in 1983

Homa Bay地区病院のコレラ検査室で調べられた約17,000検体のうち再検例を除く,1,301検体が陽性者で,うち入院者788名,健康保菌者513名であった.コレラ感染率は13～19歳の男性に最も少なく,15～39歳の女性に最も高かった.流行は3月と7月にみられ,いずれも乾期の終わりで雨期に入る直前であった.月別・年齢別にみると,3月は20～39歳,7月は13～19歳に最も多くみられた.地区別にみると,KarachuonyoとKanyadaに患者は集中していた.致命率は9%と高く,発展途上国のもつ,共通の背景があるように思われた.家族内感染は161例に認められ,他は散発例であった.薬剤感受性については,1982年に多剤耐性株が若干認められたが,1983年のほとんどが耐性株であり,O/129にも耐性を示した.耐生パターンはタンザニア分離株のそれとも異なっており,コレラ菌の土着性を思わせた.この疫学調査で最も重要なことはコレラは再感染がほとんど認められないということであった。即ち,有効なワクチン開発の可能性が大であることを示唆している.More than 17,000 rectal swab specimens were examined for Vibrio cholerae Ol at Cholera Laboratory in Homa Bay District Hospital. Out of these specimens, 1,301 cases were bacteriologically cholera-positive excluding repeated specimens. The number of admitted cases and healthy carriers were 788 and 513 respectively. Infection rate of cholera was lowest in the age-group, 13-19 of male. It was highest in female of childbearing age-group (15-39). Monthly variation of cholera-positive cases showed two peaks in March and July, closely correlated with the dry season. Monthly variation of cholera by age-group also showed two peaks in March and July. The former peak was formed by the age-group of 20-39 and the latter was by 13-19. High infection rate was found in Karachuonyo and Kanyada. The mortality of the admitted cases was 9%. One hundred and sixty-one cases were thought to be caused by family contacts, however most of the others were sporadic cases. Tetracycline resistant strains were isolated in 1982 even in Kenya, though the number was small. Most of the strains isolated in 1983 were resistant to multiple antimicrobial agents as well as O/129 which is a vibriostatic agent

Plague and the Human Flea, Tanzania

Pulex irritans fleas were more common in villages with high plague incidence

Chronic hepatosplenomegaly in African school children: a common but neglected morbidity associated with schistosomiasis and malaria.

Chronic hepatosplenomegaly, which is known to have a complex aetiology, is common amongst children who reside in rural areas of sub-Saharan Africa. Two of the more common infectious agents of hepatosplenomegaly amongst these children are malarial infections and schistosomiasis. The historical view of hepatosplenomegaly associated with schistosomiasis is that it is caused by gross periportal fibrosis and resulting portal hypertension. The introduction of ultrasound examinations into epidemiology studies, used in tandem with clinical examination, showed a dissociation within endemic communities between presentation with hepatosplenomegaly and ultrasound periportal fibrosis, while immuno-epidemiological studies indicate that rather than the pro-fibrotic Th2 response that is associated with periportal fibrosis, childhood hepatosplenomegaly without ultrasound-detectable fibrosis is associated with a pro-inflammatory response. Correlative analysis has shown that the pro-inflammatory response is also associated with chronic exposure to malarial infections and there is evidence of exacerbation of hepatosplenomegaly when co-exposure to malaria and schistosomiasis occurs. The common presentation with childhood hepatosplenomegaly in rural communities means that it is an important example of a multi-factorial disease and its association with severe and subtle morbidities underlies the need for well-designed public health strategies for tackling common infectious diseases in tandem rather than in isolation

ケニア諸地域住民の腸管寄生原虫感染状況

1980年5月から11月の間にケニアのNaivasha，Kitui，M achakos，Taveta及びNandi Hillsの住民2,114人から採取した糞便についてホルマリン・エーテル法により腸管寄生原虫のシストの検査を行い感染状況を調査した。その結果，赤痢アメーパは31.8%， 大腸アメーパは52.3%と極めて高率を示し，その他は小形アメーパ4.8%，ヨードアメーパ8.7%，ランブル鞭毛虫8.3%，メニール鞭毛虫10.4%であった。腸トリコモナス及びEntamoeba hartmanniも少数例検出されたが，大腸パランチジウムやイソスポーラなどは検出されなかった。総陽性率(陽性総数/検査総数)は75.1%にも及び，飲料水，食物など生活環境が糞便によって高度に汚染されていることが示唆された。陽性率に男女聞の有意差は認められなかった。年齢別にみると，4歳以下の乳幼児でもすでにかなり高率に感染がみられるが，ランプノレ鞭毛虫を除き，特に30歳代から40歳代で最高値を示した。ランプル鞭毛虫は若年齢層ほど高い陽性率を示し4歳以下が最高であった。本調査は日本国際協力事業団(JICA)の医療協力「ケニア伝染病研究対策プロジェクト」の一環として行われたものであり，その撲滅対策を，戦後日本で実施され成果をあげた寄生虫予防対策事業との関連において考察した。During the period from May to November in 1980, a total of 2,114 stool specimens were collected from individuals living in Naivasha, Kitui, Machakos, Taveta and Nandi Hills areas in Kenya, and they were examined for intestinal protozoa by formol-ether concentration method followed by idoine-staining. Out of 2,114 specimens 673 (31.8%) were positive for Entamoeba histolytica, 1,105 (52.3%) for Entamoeba coli, 102 (4.8%) for Endolimax nana, 184 (8.7%) for Iodamoeba butschlii, 176 (8.3%) for Giardia lamblia, and 220 (10.4%) for Chilomastix mesnili. The total positive rate, which means the percentage of positive persons for any kinds of intestinal protozoa, was 75.1 per cent

東アフリカ・ケニア，タベタ地区におけるヒト住血吸虫症の浸淫状況

1974年にタベタ地区の3村落の住民に皮内反応と検使，検尿による住血吸虫卵の検出を試み，963名の結果について集計を行った。皮内反応の抗原としてはVBS adult S.japonicum antigen (1:10,000 dilution)を用い，糞便と尿の検体は集卵法l乙て検査した。虫卵陽性率はJipe 62.2%，Eldoro 68.0%, Kivalwa 69.6 %であった。Jipeでは主にS.mansoni，KivalwaではS.haematobium，Eldoroでは両種の浸淫が認められた。Eldoroでは男性より女性に虫卵陽性率が高かったが，JipeとKivalwaでは推計学的に虫卵陽性率の有意な性差は認められなかった。虫卵陽性率は小児では年齢と共に上昇し，5歳と14歳の間で最高値に達し，以後次第に減少した。皮内反応の陽性率は全体で76.4%で，虫卵陽性率より高い。小児では虫卵陽性者の多数で，皮内反応は弱いか或は全く反応を呈さなかった。皮内反応陽性率は年齢と共に増加し，40歳以上の住民では95%に達した。Jipeでは女性より男性に皮反内応陽性率が高かったが， EldoroとKivalwaでは性差は認められなかった。虫卵陽性の者ではS.mansoni感染者とS.haematobium感染者の聞に皮内反応の差は認められなかった。1975年にJipe，Kivalwa，Kuwahoma，Chalaの村落住民に検便と検尿を行った。KuwahomaではS.haematobiumの浸淫が認められた。Chalaでは住血吸虫の感染は稀であった。この限られた地域にそれぞれS.mansoni，S. haematobiumの感染が流行する村落，両種の感染の流行する村落が存在することが確認された。これら両種の住血吸虫症の流行する地域の疫学的調査に於て，皮内反応にVBS adult S. japonicum antigenを，検便，検尿に集卵法を用い得ることが明らかにされた。A total of 963 individuals in three villages were examined for schistosomiasis by both skin test and schistosome ova detection in stool and urine in 1974. The antigen used for skin test was VBS adult S. japonicum antigen (1: 10,000 dilution). Stool and urine samples were examined through the concentration methods. Egg-positive rate was 62.2 per cent in Jipe, 68.0 per cent in Eldoro, 69.6 per cent in Kivalwa. Jipe was infested mostly by S. mansoni, Kivalwa by S. haematobium and Eldoro by both two schistosomes. The egg-positive rate was higher in females than in males in Eldoro. In Jipe and Kivalwa, however, the differences in the rate between males and females were not statistically significant. The rate increased with age in children, reached a peak between the ages of 5 and 14 years and then decreased gradually. The positive rate of skin test was 76.4 per cent in total, higher than that of stool and urine examinations. The skin reaction was weak or absent among many egg-positive children. The skin-test positive rate increased as the age advanced and reached 95 per cent in inhabitants from 40 years up. The positive rate of skin test was higher among males than females in Jipe. No significant difference in the rate between males and females was found in Eldoro and Kivalwa. Among the egg-positive subjects there was no significant difference in skin reaction between S. mansoni infection and S. haematobium infection. In 1975 stool and urine samples from Jipe, Kivalwa, Kuwahoma and Chala were examined. Kuwahoma proved to be infested by S. haematobium. In Chala schistosome infection was rare. There exist villages infested by S. mansoni and/or S. haematobium in the small area. It seems that VBS adult S. japonicum antigen for skin test and the concentration methods for stool and urine examinations are of use in the epidemiological survey in the areas where S. mansoni and/or S. haematobium infections are prevailing