Prevalencia de las infecciones por virus de las hepatitis B, C, D y E en Bolivia

Abstract

In Bolivia, no studies have been carried out specifically on hepatitis viruses. Thus, their prevalence and circulation patterns are virtually unknown. A seroepidemiologic study was performed from 1992 to 1996 to generate a preliminary idea of the overall prevalence of infection from hepatitis B, C, D, and E viruses (HBV, HCV, HDV, and HEV, respectively) in different Bolivian population groups. Prompted by the data obtained in other areas of Latin America, the study focused on indigenous communities in the Amazon region. In rural areas of the high Andean plateau, HBV infection showed an overall prevalence compatible with medium to low endemicity (11.2%), and no carriers of HCV or HDV antibodies were found. In two high-risk groups in the city of Cochabamba (homeless children and sexual workers), the prevalence of HBV infection was similar (11.6%) and could be considered low by comparison to that of similar population groups in Latin American urban centers. The prevalence of HCV (one positive case, or 0.5%) was similar to that found in similar population groups, although the small number of samples precludes drawing more definite conclusions. As has been noted previously with similar communities in tropical areas of South America, HBV infection is highly endemic in indigenous populations of the Bolivian Amazon (with an overall prevalence of 74.0%), but circulation of HCV has not been detected. It is a well-known fact that HBV is horizontally transmitted and that transmission can take place very early in life, but the mechanisms involved are unknown. By 10 years of age, more than half the population has already had the natural infection that, in approximately 10 more years will have affected virtually the entire population. The very low rate of positivity to HBsAg (1.6%), the absence of viral DNA in samples showing isolated positivity to anti-HBc, and the high prevalence of anti-HBs among individuals who show markers for natural infection (92.4%) suggest vertical transmission plays no role in persistent endemicity. So far, no outbreak of HDV infection has been documented in these communities, but the high endemicity shown by HBV points to the possibility of future outbreaks. Results obtained with tests for the detection of antibodies against HEV suggest that this virus is circulating widely in Bolivia and that it could have caused recent outbreaks in Cochabamba state. Vaccination against HBV in endemic populations is recommended as a short-term measure. Also recommended are actively searching for outbreaks and sporadic cases of hepatitis E in the entire country and performing additional research that will help in assessing the public health consequences of the situation described in this article.

Prevalence of hepatitis B virus infection and related risk factors in a rural community of Mexico.

“…14 The overall observed prevalence is similar to the reported one in non-drug abusing prostitutes in Mexico City. 15 Nevertheless, the prevalence is lower than the reported one in some Latin American and Caribbean countries, 2 as has been notified in Brazil, 16 Bolivia, 9 Nicaragua, 17 Jamaica, 18 or Belize. 5,19 San Juanito could be considered as a low endemicity area of hepatitis B.…”

“…5,9,10 Several studies have been conducted in Mexico, but most of them have been carried out in urban populations. No population-based prevalence study has been conducted so far in rural communities of Mexico; nor have they included indigenous inhabitants.…”

An outbreak of fulminant hepatitis delta in the Waorani, an indigenous people of the Amazon basin of Ecuador.

“…In fact, the Waorani have the highest HBV prevalence of any Amazonian group investigated to date. [1][2][3][4][7][8][9] Many investigators have sought to determine the modes of transmission of HBV, particularly in populations where it is hyperendemic. Vertical (perinatal) transmission alone would not be adequate to produce the high prevalence of HBV infection seen among the Waorani, since only 11% of reproductive age women appear to be carriers of the virus.…”

“…Serologic markers for HBV infection have been found at rates of 25 to 83% among Amazonian peoples in Bolivia, Brazil, Peru, and Venezuela. [1][2][3][4][5][6][7][8][9] A study of the Waorani, an indigenous people of the Amazon basin of Ecuador, reported antibodies to the Hepatitis B core (HBc) in 74% of people living in three villages, but none of those living in a fourth community. 10 Infection with hepatitis D virus (HDV) can only occur in individuals who are also infected with HBV.…”

“…11 Superinfection of HBV carriers with HDV, or simultaneous infection with HBV and HDV, has been found to cause fulminant and sometimes fatal hepatitis. [4][5][6]9,[12][13][14][15] Evidence of HDV infection has been found in various South American groups in which HBV infection is endemic 1,[3][4][5]7,16 and not in others. 2,8 To our knowledge, HDV infection has never before been reported in Ecuador.…”