Socio-environmental variables and transmission risk of lymphatic filariasis in central and northern Mozambique

Abstract

Abstract. Lymphatic filariasis (LF) is endemic in Mozambique, where it is caused by Wuchereria bancrofti with Culex quinquefasciatus as the main vector. It affects approximately 10% of the population (2 million) with about 16 million at risk. Prevalence rates in 40 out of 65 districts that together comprise the four endemic provinces Niassa, Cabo Delgado, Nampula and Zambezia were analysed with the aim of elucidating the socio-environmental variables influencing the transmission. The levels of prevalence were divided into six ranks and certain climatic, environmental and social factors were considered independent variables. A climadiagram was created and the LF risk and the water budget-based index were calculated for each district. Factors influencing the risk of the overall transmission and that of the provincial levels were established by discriminant analysis. The results show that LF transmission increased with mean maximum temperature and decreased with altitude. The almost constant annual temperature (especially in the tropical area), altitude, general economic conditions and predominant crop production (rice) were found to be responsible for the abundance and presence of the vector. However, despite the presence of the vector in the hinterland, presence and survival of the parasite were not found to be favoured there. The transmission risk was found to be highest in Zambezia, and consequently also the prevalence, while the situation in Niassa was the opposite. The conclusion is that temperature, altitude and the development/poverty index (particularly in the urban areas) have to be considered as transmission risk factors for LF in Mozambique. The extent of rice culturing probably also plays a role with respect to this infection.

Prevalence and Correlates of Lymphatic Filariasis Infection and Its Morbidity Following Mass Ivermectin and Albendazole Administration in Mkinga District, North-Eastern Tanzania

“…Some villages depicted low prevalence of CFA, which might be due to various interventions creating synergy besides the MDA, such as the use of insecticide-treated nets or local insecticide repellants (smoke, herbs), as observed in studies conducted elsewhere [34]. In some cases, the presence of climatic and environmental conditions that are unfavorable for vector survival could contribute to low infection or positivity rates, even in areas where compliance to MDA is low [35]. However, this study did not explore the entomological characteristics and, therefore, no link could be established in this case, albeit other studies had reported similar conclusions [36].…”

Lymphatic filariasis in Luangwa District, South-East Zambia

“…However, except for results from recent field surveys in Malawi [2-4] and a socio-environmental study on transmission risk in northern Mozambique [5], knowledge on LF infection, disease and transmission patterns in the central and southern region of Africa is limited. Available information from case reports and historic surveys indicate, though, that LF has a wider distribution in this part of Africa [6-9].…”

Frequency and distribution of neglected tropical diseases in Mozambique: a systematic review

“…In addition, there was a lower frequency of cases in people < 15 years old [53]. In 2009, Mozambique was still one of the 39 African countries that are endemic for LF, with 16 million people estimated at risk and two million infected; Cabo Delgado and Nampula were the provinces with higher risk [54].…”