Role of arthropods in transmission of hepatitis-B virus in the tropics

Bed bugs: clinical relevance and control options

Since the late 1990s, bed bugs of the species Cimex lectularius and Cimex hemipterus have undergone a worldwide resurgence. These bed bugs are blood-sucking insects that readily bite humans. Cutaneous reactions may occur and can start out as small macular lesions that can develop into distinctive wheals of around 5 cm in diameter, which are accompanied by intense itching. Occasionally, bullous eruptions may result. If bed bugs are numerous, the patient can present with widespread urticaria or eythematous rashes. Often, bites occur in lines along the limbs. Over 40 pathogens have been detected in bed bugs, but there is no definitive evidence that they transmit any disease-causing organisms to humans. Anemia may result when bed bugs are numerous, and their allergens can trigger asthmatic reactions. The misuse of chemicals and other technologies for controlling bed bugs has the potential to have a deleterious impact on human health, while the insect itself can be the cause of significant psychological trauma. The control of bed bugs is challenging and should encompass a multidisciplinary approach utilizing nonchemical means of control and the judicious use of insecticides. For accommodation providers, risk management procedures should be implemented to reduce the potential of bed bug infestations.

The return of the common bedbug

The incidence of skin disease secondary to infestation with the human bedbug, Cimex lectularius, has increased dramatically in the United States and in the United Kingdom. We describe a child with a recurrent pruritic eruption of urticarial, erythematous papules on the face, neck, and extremities. The etiology of her cutaneous lesions was discovered to be a bedbug infestation in the home. The epidemiology, entomology, presentation, and treatment of bedbugs and their bites are discussed.

[Prevalence of serologic markers of hepatitis B and D viruses in children of the Caiabi and Txucarramãe tribes from the Indian Reservation of Xingu, central Brazil]

The medical literature has shown that the inhabitants of the Amazon region are highly affected by hepatitis B and delta viruses infection, but this has never been studied in Indian children by age group. A study of the prevalence of serological markers of hepatitis B and delta viruses in Indian children aged 0 to 14 years living in the PIX was carried out. This Park is located in Central Brazil, a region which is in the transition between the savannab to the south and the Amazon jungle to the north. To determine the prevalence of HBV and HDV markers in Indian children and to characterize the route of HBV transmission in this region. Out of the 17 tribes living in the PIX, two--the Caiabi and the Txucarramãe--were chosen because both live in the North part of the Park, but have quite different ways of life. The overall prevalence of HBV serum markers was: HBsAg, 4.5%; anti-HBs, 39.6%; anti-HBc, 44.1%; any marker of HBV, 47.3%; and anti-HDV, 0.0%. However, a striking difference in the prevalence of hepatitis B markers was observed between the two tribes: younger Caiabi children were much less affected than the Txucarramãe ones. The prevalence of HBsAg in fertile women was 12%, being anti-HBe positive. Our data suggest that HBV infection is highly prevalent among Indian children living in this Indigenous Park and vertical infection is not an important route of transmission in either tribes.

Hepatitis B epidemiology and cultural practices in Amerindian populations of Amazonia: the Tupí-Mondé and the Xavánte from Brazil

Hepatitis B infection and disease are highly endemic in South America. Prevalences of positivity are particularly high in Amazonia, and among Amerindian peoples in particular. This paper reports the results of a seroepidemiological survey for hepatitis B virus (HBV) carried out among four Amerindian populations from the Brazilian Amazon region: Gavião, Surui, Zoro and Navate. Rates of positivity to HBV serological markers (HBsAg, anti-HBs and or anti-HBc) are very high for the four groups, ranging from 62.8 to 95.7%. It is argued that the high rates of positivity in the Amerindian groups dealt with in this study, as well as for other Amazonian populations, are related to a complex of cultural practices which enhance the likelihood of HBV transmission (bloodletting, scarification, tattooing and orally processed food, among others). The authors suggest that, due to unique patterns of interaction between sociocultural and environmental factors. HBV infection assumes a specific profile in native Amazonian societies.

Prevalence of hepatitis B in !Kung (San) children from Bushmanland, Namibia

Serum samples from 248 predominantly !Kung children (aged 5-19 years) attending various bush schools and a clinic in Bushmanland, northern Namibia were examined for the presence of hepatitis B virus (HBV) markers by radioimmunoassay. HBsAg was detected in 18 (7.3%) children while 117 (47.6%) showed one or more markers of HBV infection. These prevalence rates are lower than those of the closely situated territory of Kavango to the north and East Caprivi to the north-east. No significant difference in HBs antigenaemia between !Kung boys and girls was found (p > 0.05). However, HBs antigenaemia was found to vary between children in different bush schools. A significantly higher number of children attending the Omatako bush school were positive for HBsAg than the number attending the Luhebu bush school (p < 0.0167). These local variations could assist in the initial targeting of HBV vaccine to high-risk areas. In situ investigations of hyperendemic foci in Bushmanland, Namibia should help to elucidate the variation in HBs antigenaemia and the factors responsible for transmission of HBV.

Horizontal transmission of hepatitis B virus amongst British 2nd World War soldiers in South-East Asia

Infection with hepatitis B virus (HBV) is much more common in tropical than in temperate countries. Visitors to the tropics are thus at risk from HBV, though the degree of risk, and the routes of infection involved are uncertain. We report serological markers of HBV in two groups of 2nd World War soldiers, who served in the Thai/Burma jungles. The groups comprised 100 ex-prisoners of the Japanese (POW), and 100 Burma Campaign Veterans (BCV). Surface antigen to HBV (HbsAg) was positive in 0% of POW and 2% of BCV (P = not significant). Surface antibody (anti-HBs) and core antibody (anti-HBc) were both positive in 40% POW and 13% BCV (P less than 0.001). Quoted UK prevalence rates for these markers are 0.1% for HBsAg, 1.5% for anti-HBs and 0.7% for anti-HBc. Both groups thus show very high rates of past HBV infection. For the POW there were many possible reasons, including contaminated surgical instruments and needles, blood transfusions, and multiple beatings with common weapons. None of these factors operated significantly for BCV. Malarial transmission was, however, intense in both groups, though more so in POW. The data thus again raise the possibility of horizontal transmission of HBV by biting insects in tropical countries.

Relationship between the prevalence of antibodies to hepatitis B core antigen and arbovirus in fishermen from the Ribeira Valley, Brazil

Sera from 299 fishermen 16 to 80 years old, residents in Cananeia and Iguape counties, southern cost of São Paulo State, Brazil, were studied in order to identify a possible association between the prevalence of specific antibodies to the hepatitis B virus (HBV) and exposure to haematophagus mosquitoes evaluated by the prevalence of arbovirus antibodies. This professional group presented the highest prevalence of arbovirus antibodies (54.1%) in past investigations carried out in this heavily forested region. Detection of antibody to hepatitis B core antigen (anti-HBc) in the sera was done by enzyme immunoassay (Roche). Prevalence of anti-HBc antibodies in this group was 31.4% (94/299) which is very high compared with 7.2% to 15.0% for different groups of healthy adults in State of São Paulo. No significant difference is observed between the prevalences of HBV antibodies in Iguape and Cananeia. Prevalence of anti-HBc and anti-arbovirus antibodies increases with age. There is a concordance in the distribution according to age groups of the frequency of anti-HBc and anti-arbovirus positive sera. Ag HBs was detected in 4% of the studied sera. These results support the hypothesis that the transmission of the hepatitis B virus and the arboviruses may be due to the same factor, one of the possibilities would be by anthropophilic mosquitoes.

Induction of skin papillomas in the rabbit, Oryctologus cuniculus, by bites of a blood-sucking insect, Cimex lectularius, irradiated by gamma rays

Bed bugs, Cimex lectularius, irradiated with gamma rays were allowed to suck blood from shaved areas of the skin of rabbits, Oryctolagus cuniculus, 2 times/week for 5 months and then once weekly for another 5 months. This significantly induced the formation of skin papillomas and sweat gland hyperplasia in five out of nine experimental animals. It is speculated that the saliva of the irradiated bugs was activated by gamma rays and was responsible for the induction of skin papillomas. Because bed bugs play a significant role in the transmission of virus, it is also speculated that there is a virus in the saliva of bugs; this virus may be activated by gamma radiation and causes the development of papillomas in the skin.

Relationship between the prevalence of antibodies to arbovirus and hepatitis B virus in the Vale do Ribeira region, Brazil

280 students, between 6 and 14 years old, residents in the Iguape county, southern coast of the State of São Paulo, were studied in order to identify the existence of a possible association between the prevalence of specific antibodies to the hepatitis B virus and the exposure to haematophagous mosquitoes, evaluated indirectly through the prevalence of antibodies to 17 arboviruses isolated in Brazil. The children were from 4 areas with different topographical characteristics: 89 of the children were from the urban zone of the town of Iguape, 89 were from the peri-urban zone, 30 were from the rural area with extensive banana plantations, and 72 were from the jungle zone. Previous studies had shown significantly higher prevalence of antibodies to different arboviruses in the cultivated zone and the jungle zone, when compared to the urban and peri-urban zones of Iguape. The detection of antibodies to the HBV surface antigen (HBs Ag) was done through the radioimmunoassay (Ausab, Abbott Laboratory). The cases considered positive were confirmed through the presence of anti-core HBV antibodies (anti-HBc-EIA Roche). A significantly higher prevalence of anti-HBV antibodies was observed in children from the jungle zone (26/72 = 36.1%) when compared to those from the urban zone (5/89 = 5.6%), peri-urban (6/89 = 6.7%) or from the cultivated zone (0/30 = 0%). The result suggest the existence of a common factor in the dissemination of the arboviruses and the hepatitis B virus, supporting the hypothesis that mosquitoes may play an important role in the HBV transmission in tropical forested region.

Epidemiologic study of hepatitis B in pregnant Korean women

The positive rates of hepatitis B viral markers according to many epidemiologic factors were analyzed in 2,873 pregnant women who delivered at St. Columban’s Hospital in Mokpo City from April 1st, 1985 to March 31st, 1986.

The following results were obtained: The overall HBsAg positivity in all pregnant women was 8.3%. The positive rate of HBsAg was unrelated to age. It was 13.2% in the 11–20 year age group. 12.5% in the 31–40 year age group, 7.8% in the 21–30 year age group and 0.0% in the 41–50 year age group. The positive rate of HBsAg was slightly related to locality. It was a little higher in women who grew up in rural areas (8.6%) than in urban areas (7.7%). The positive rate of HBsAg was unrelated to educational background. The positive rate of HBsAg was unrelated to economic status. It was 8.7% in the highest income group and 8.6% in the lowest income group. The positive rate of HBsAg was higher in cases who had injections more than four times. The positive rate of HBsAg was higher, but not significantly, in cases who had received blood transfusion. The positive rate of HBsAg was higher, but not significantly, in cases who had more than three siblings (0.05

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Prevalence of hepatitis B virus infection among black children in Soweto

Roughly 15% of black children in rural areas of southern Africa are carriers of the hepatitis B virus. The purpose of the present study was to determine the prevalence of chronic hepatitis B virus infection among urban black children born and growing up in Soweto. A total of 2364 children were studied, ranging in age from 3 to 19 years, and of these, 1319 (56%) were girls. The children were drawn from the highest and the lowest socioeconomic classes. Serum samples were tested for all hepatitis B virus markers as well as IgG antibody against hepatitis A virus. HBsAg was detected in 23 (0.97%) of the children, anti-HBc and anti-HBs together in 155 (6.6%), anti-HBc alone in 17 (0.7%), and anti-HBs alone in 72 (3%). Of the 2364 children, 2097 (88.5%) were negative for all hepatitis B virus markers. IgG antibody to hepatitis A virus was present in 175 (97%) of a sample of 179 children. There was no difference in prevalence of hepatitis B virus markers between children from the upper and lower socioeconomic classes. HBsAg was more common in boys (16 out of 1043 (1.5%) than girls (seven out of 1321 (0.57%), and the prevalence of all hepatitis B virus markers increased with age. The youngest carrier of hepatitis B virus was 7 years old. The remarkable difference in the hepatitis B virus carrier rate between urban and rural black children offers a unique opportunity to investigate the favourable influences operating in an urban environment to limit the prevalence of hepatitis B virus infection.

Hepatitis B infection in households of acute cases

Seroepidemiological studies conducted in 369 household contacts of 80 acute cases of hepatitis B in Singapore showed that asymptomatic chronic carriers of hepatitis B surface antigen (HBs Ag) are the main source of acute hepatitis B infection. The HBs Ag prevalence rate in asymptomatic household members was 20% compared with a 6% prevalence for the general population. The majority of the household carriers (60%) were highly infectious with positive hepatitis e antigen (HBe Ag). The overall prevalence of HBV infection (with at least one HBV marker) of the household contacts was 40.7%. Spouses and parents of acute cases had a significantly higher prevalence of HBV infection than other members of the families. HBV prevalence rate showed no association with the household size. Factors associated with the risk of transmission of HBV infection included sharing of various personal and household articles, such as toothbrush, towel, handkerchief, clothing, razor, comb, bed and bedding. Sleeping in the same bedroom, eating together at meals, and sharing of eating and drinking utensils were not associated with an increased risk of transmission of infection. Follow-up studies six months later showed that 30% of the acute cases became chronic HBs Ag carriers (with 46% HBe Ag positive), thus providing an additional source of infection in the families, while 8% of the susceptible household members acquired asymptomatic HBV infection. Health education on the prevention of HBV transmission in the homes of acute cases should be based on sound epidemiological information. Household contacts of acute cases of hepatitis B should be routinely screened and the susceptible vaccinated against the disease as soon as possible.

Hepatitis B virus carrier state in black children in Ovamboland: role of perinatal and horizontal infection

Hepatitis B surface antigen (HBsAg) was detected in 17% of adult males and 11% of mothers in Ovamboland , South West Africa/Namibia. Hepatitis B e antigen (HBeAg) was present in 15% of HBsAg-positive mothers. Only 1% of children less than 6 months of age were HBsAg-positive, compared with 13% of children over the age of 1 year. 27% of mothers who were HBsAg-positive had HBsAg-positive children, whereas the corresponding figure for mothers who were HBsAg-negative was 6%. 63% of mothers who were positive for both HBsAg and HBeAg had HBsAg-positive children. 37% of HBsAg-positive children had HBsAg-positive mothers, compared with 8% of HBsAg-negative children. Later "horizontal" rather than neonatal maternal-infant transmission of the hepatitis B virus (HBV) seems to be the more important mode of spread of this infection in Ovambo children. The difference in the pattern of transmission of this virus between the Far East and Africa seems to centre mainly on the differences in the HBeAg status of the mothers in these two regions.

[Evidence of hepatitis B antigen (HBsAg) in Triatominae]

De 3.200 "manchas" provenientes de insetos dos gêneros Triatoma e Panstrogylus, positivas para sangue humano, 12 deram resultados presuntivamente positivos, por imunodifusão, para HBsAg. Deste total, só 7 casos foram confirmados como positivos, por radioimunoensaio, correspondendo todos eles a "manchas" obtidas de ninfas de Triatoma infestans.

Hepatitis-B: a review

The recent literature on various aspects of hepatitis-B is reviewed with emphasis on the interrelationships of viral structure, antigenic components, and host immune response in acute, chronic, and asymptomatic carrier states of the infection. The mode of replication and mechanisms of transmission are discussed. Special attention is paid to potential non-parenteral routes of spread. The role of hepatitis-B in associated immune complex diseases and in hepatoma is outlined. A guide to the interpretation of serologic tests for hepatitis-B associated antigen and antibody patterns is presented in relation to the clinical stage and prognosis of the infection. Therapy, except in conceptual terms, is not covered but a summary of the current status of active and passive immunization is given. The unresolved question of the infectivity of carrier medical staff for their patient contacts, and the reverse, is discussed.

Hepatitis B in Australian Aborigines and Torres Strait Islanders: georgraphical, age and familial distribution of antigen subtypes and antibody

Hepatitis B antigen of subtype ay is prevalent in Australian Aboriginal populations, but only subtype ad was found in Torres Strait Islanders. Both subtypes were found in Caucasion hepatitis patients and blood donors from Brisbane. Antigenaemia in Aborigines was more prevalent in Northern Territory than in Queensland, and in males in all areas, but different age distributions were found in Queensland (maximal over 30 years) and Northern Territory (maximal under 30 years). Family clustering was striking in all populations where genealogies were known. In a limited survey antibody was found to be more common than antigen in all Aboriginal groups, the prevalence increasing with age with a peak at 11 to 30 years. Hepatitis B virus infection was equally common in some areas of high and low arbovirus activity providing some evidence against arthropod transmission of hepatitis B virus in these areas.

Epidemiologic study of the modes of spread of viral hepatitis in Greece

We studied the possible correlation of VH morbidity or HBsAg carrier rate with the prevalence of malaria and enteric among the 50 geographical regions of Greece. Malaria was considered as an index of mosquito density and enteric as an index of the local hygienic conditions. Morbidity data on the studied reportable diseases for the period 1954-73 and the HBsAg carrier rate (4-7%) among 17,991 recruits of the Greek Air Force, coming from all the geographical regions of Greece, were used. The statistical analysis of our data showed that VH morbidity (which is mainly hepatitis A) is significantly correlated with enteric morbidity, while HBsAg carrier rate with malaria. Our data support the significance of the role of mosquitoes in the spread of HB at least under the prevailing conditions in Greece.