Epidemiological trends for human plague in Madagascar during the second half of the 20th century: a survey of 20 900 notified cases

Abstract

Summaryobjectives To describe the principal characteristics and epidemiological trends for human plague in modern times based on the largest reported series of cases from the highly active Malagasy focus.methods We used a file of 20 900 notified cases of suspected plague, 4473 of which were confirmed or probable, to carry out a statistical analysis of incidence and mortality rates and associated factors for 5-year periods from 1957 to 2001.results Our analysis of trends showed (1) an increase in the incidence rate and the number of districts affected, (2) an increase in the proportion of bubonic forms (64.8-96.8%) at the expense of the pneumonic forms (35.2-3.2%) more frequent in elderly subjects and (3) a decrease in case fatality rate (CFR, 55.7-20.9%) associated with five factors: clinical form, season, province, urban/ rural and period considered. The median age of patients was 14 years and more men than women were affected.conclusions Since the end of the 1980s, the incidence of plague in Madagascar has increased in both rural and urban areas, because of multiple socioeconomic and environmental factors. However, the plague mortality rate has tended to decrease, together with the frequency of pneumonic forms, because of the strengthening of control measures. Making dipstick tests for the rapid diagnosis of human cases and epizootics in rats available for health structures should make it possible to raise the alarm and to react rapidly, thereby further decreasing morbidity and CFR.

Mortality risk factors show similar trends in modern and historic populations exposed to plague

“…Children, especially those sleeping or playing on the ground, have a much higher level of exposure to the bites of infected fleas [35,36]. Furthermore, since the immune system becomes stronger with age, young children may be less able to defend themselves by developing a semi-immunity against the plague bacterium in endemic areas (i.e.…”

“…Furthermore, since the immune system becomes stronger with age, young children may be less able to defend themselves by developing a semi-immunity against the plague bacterium in endemic areas (i.e. the Malagasy central plateau and Medieval and Modern Europe) [35,36].…”

Predicting Potential Risk Areas of Human Plague for the Western Usambara Mountains, Lushoto District, Tanzania

“…34,35 Plague occurs mainly in highlands in DRC 7 and Uganda, where plague cases were more common at > 1,300 m. 13,36 In Madagascar, plague-endemic areas focus on the high plateau of the island. 37 In the western United States, a geographical information system (GIS) -based model indicated that suitability for plague increases for elevations up to 2,129 m but declines at higher elevations. 38 Besides elevation, plague occurrences seem to be linked to seasonal vegetation changes, resulting from rainfall variability through the year, and to moderate EVI values and reasonably high seasonality, suggesting that forests are not suitable for plague; however, because people do not frequently live in the forests, this conclusion could be misleading.…”

Current perspectives on the spread of plague in Africa

“…90,108 The high transmission season of the disease to humans has been associated with low abundance of rats and the high chance of accession of fleas to human dwellings. [109][110][111] In the central highlands, most human cases are noted between September and March. This period is characterized by a warmer rainy climate than the low transmission season, which extends from April to August.…”

“…135 Onsets of pneumonic plague during such ceremonies have been documented, suggesting that handling of potentially plagueinfected corpses may be the cause. 69,108,111 Thus, the Malagasy Ministry of Health recommended a minimum period of 7 years between death and exhumation of a plague victim, and before any transfer of a corpse from one village to another. 69 Migration and transportation of goods containing infected rats or fleas is another factor favoring rapid transmission of plague in the country.…”