The economic crisis since 2000 in Zimbabwe has led to a rapid rise in TB cases and rising rates of malnutrition. However, it appears that HIV prevalence in pregnant women is decreasing, Dr M Silverman reported to the Fifth International AIDS Society Conference in Cape Town.
This study is the first to demonstrate an association between rising TB incidence and national economic decline in the absence of armed conflict.
Zimbabwe has undergone an economic collapse since 2000 characterised by political crisis, hyperinflation and a real GDP reduction of 40% between 2000 and 2007 and a further 14% decrease in 2008.
Since 1995 to 31 March 2009 information has been prospectively collected on diagnoses made at a rural mission hospital, Howard Hospital, in Zimbabwe. National surveillance data showing a decline in TB incidence since2004 is likely to be skewed, given that most health care facilities shut down during the peak of the economic crisis.
Howard Hospital is one of the few mission hospitals that remained functioning and hence its data are likely to be more reliable for determining burden of disease.
During the period of the study from 1995 to 2009, 8,770 cases of tuberculosis (TB), 6, 695 cases of nutritional diseases and 27 399 cases of diarrhoea were diagnosed. 81.8% of the TB cases were coinfected with HIV.
Between 1995 and 2001, the study found that TB incidence had risen gradually from 176 per 100,000 to 281 per 100,000, however this finding correlated with the rising HIV epidemic in Zimbabwe.
However, a further rapid rise in TB incidence to 426 per 100 000 corresponded with the onset of hyperinflation between 2003 and 2007 (p<0.05). During this period there was also an increase in the incidence of pellagra, kwashiorkor and diarrhoeal illnesses.
TB incidence remained stable between 2003 and 2007, but rose a further 35% in 2008 to 556 per 100 000 (p<0.01), with a further 15% increase occurring in the first five months of 2009.
Monthly time-series analyses showed that increasing economic inflation was associated with subsequent increases in TB incidence.
A seasonal pattern in TB incidence was observed by the investigators.
Diagnoses were lowest at harvest time and in the following three months, when food was plentiful, but increased significantly when food was scarce (p < 0.01). The rising TB incidence did not reflect patterns of migration as all data collected only reflected patients already living in the catchment area of the hospital.
A total of 18,746 antenatal HIV tests were conducted at the mission hospitals during the period of the study and 3,636 were positive. HIV prevalence at antenatal clinics fell significantly during the period of the study from 23% in 2001 to 11% at the end of 2008 (p < 0.01). This decline was seen even though HIV testing rates remained high and stable at above 90%.
This decline in HIV seroprevalence during the peak economic crisis year when public health programmes had essentially collapsed in Zimbabwe suggests that economic decline may be decreasing HIV seroprevalence in pregnant women.
Investigators suggested that this may be due a decrease in sexual mixing and thus lower rates of infection, or possibly increased death rates or decreased fertility in HIV-positive women due to lack of nutrition and starvation.