From Plasmodium vivax outbreak to elimination: lessons learnt from a retrospective analysis of data from Guantang

Abstract

Background Malaria was once a serious public health problem in China, with Plasmodium vivax the major species responsible for more than 90% of local transmission. Following significant integrated malaria control and elimination programmes, malaria burden declined, and since 2017 China has not recorded any indigenous case. To understand the historical malaria transmission patterns and epidemic characteristics in China and insights useful to guide P. vivax malaria control and elimination elsewhere, a retrospective study was carried out. Methods Historical data from a pilot study conducted in Guantang, Luyi in central China from 1971–1995, were digitized. The data included monthly numbers of reported cases, febrile cases, parasite carriage rates, the neonatal infection rate, and entomological data regarding Anopheles sinensis. Results Following 25 years of continuous integrated malaria control activities, malaria incidence in Guantang decreased from 4,333 cases per 10,000 in 1970 before integrated implementation to 0.23 cases per 10,000 in 1991, and no cases in 1992–1995. Some fluctuations in incidence were observed between 1977 and 1981. During the period parasite rates, antibody levels and the neonatal infection rate also decreased. The pattern of seasonality confirmed that P. vivax in Henan Province was primarily of the long incubation type (temperate) during non-transmission period. The findings retrospectively provide a scientific basis for the implementation of mass campaigns of liver stage hypnozoite clearance. Entomological studies indicated that An. sinensis was the only vector, and it preferred bovine to human hosts, predominantly biting and resting outdoors. Mosquito densities declined between 1971 and 1984. Conclusion The integrated malaria control approach in Guantang effectively controlled malaria and achieved elimination. Analysis of the effectiveness of the programme can provide guidance to other regions or countries with similar ecological settings aiming to move from malaria control to elimination. There is a potential challenge in the maintenance of non-transmission status owing to imported cases and the long dormancy of liver stage hypnozoites.

Prevalence, Parasite Density and Determinants of Falciparum Malaria Among Febrile Children in Some Peri-Urban Communities in Southwestern Nigeria: A Cross-Sectional Study

“… 71 In accordance with this, studies from Ethiopia, 72 Kenya, 73 Tanzania, 74 and India 75 have revealed higher number of mosquito larvae in ponds and dams and higher malaria parasite prevalence among people living around such ponds and dams. Similarly, this finding conforms with the report of Yang et al 76 who reported a higher malaria infection among those who depend on unprotected water as a source of household water supply. Furthermore, children of household having stagnant water around their homes are four-fold likely to have malaria infection compared to their counterparts who do not have stagnant water around their homes.…”

The empirical support for the radical cure strategy for eliminating Plasmodium vivax in China

“…However, before China's malaria control and elimination program was launched, a large number of malaria cases were observed during the non-transmission season (from February to April), which could be well explained by the first relapse episode of long-incubation cases. Previously, Yang and colleagues performed a descriptive analysis using historical monthly incidence data from the Henan province (central China) and observed clear double peaks of malaria episodes during the 1960s and 1970s further supporting our findings for both short-and long-period incubations [34].…”

Pipiserpin, a Culex factor Xa inhibitor, affects female reproductive capacity and serves as a potential target for mosquito control

“…sinensis, are preferentially zoophilic, 50 with an averaged preference ratio of 1:11.93 between humans and cattle. 51 Our results showed that Pipiserpin may be used to vaccinate animals to generate antisera, which would then be ingested when mosquitoes feed on these animals. Furthermore, the presence of undigested blood in the midgut may hinder a second round of blood feeding, which may help reduce mosquito populations.…”