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Analytical summary - Neglected tropical diseases

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A few tropical diseases are endemic to certain parts of Botswana but are of a magnitude that does not warrant deliberate control programmes similar to those of tuberculosis, malaria and HIV/AIDS. Such diseases tend to be concentrated in the northern part of the country where the moisture conditions of the 20 000 km2 Okavango delta present a favourable environment for their proliferation and transmission.

Major factors determining the prevalence and distribution of the majority of the water contact diseases include:

  • surface water availability and permanence
  • human water contact behaviour such as the risk of water contamination
  • environmental and climate factors such as rainfall and temperature.

The prevalence and distribution of the diseases therefore vary from time to time, depending on the rainfall and water flow pattern.

The control of such diseases has been integrated into the primary health care services of the districts in which they occur but monitoring of, and vigilance for, such diseases are continued. With the envisaged expansion of irrigation farming in the Okavango delta, prevalence rates for waterborne diseases may increase and it has been recommended that such irrigation projects should be preceded by disease impact assessment.

Schistosomiasis
The invading parasites in Botswana are Schistosoma mansoni and S. hematobium. Prevalence rates fluctuate depending on rainfall and have been as high as 80% or as low as 20% in defined geographical areas. Since 1983, shistosomiasis control has been integrated into the primary health care services and this has kept the disease under control.

Trypanosomiasis
Trypanosomiasis is also an important public health problem in Chobe and Ngami districts. However, there have been no recent cases since a control programme based on treatment of infected people was successfully implemented between 1985 and 1993, when the prevalence reduced from 28.7% to 6.7%. Since then, notification has been relaxed.

Leprosy
In a survey carried out in 1991 on 8235 school children and 799 contacts of 127 index cases of leprosy, a point prevalence of registered leprosy cases on multidrug therapy in five districts in northern Botswana was 0.18 per 1000. Forty-four cases of active leprosy were identified and 32% of those were newly identified during the survey. The majority of leprosy cases were found in Ngami and Chobe districts.

Filariasis
Filariasis has not been reported in Botswana nor in the neighbouring Lesotho, Namibia, South Africa and Swaziland. As such, it is not considered a public health problem in Botswana.

Cholera
Fifteen cases were reported in Francistown, a city bordering Zimbabwe, in 2008. It was well contained in that area and it is therefore considered to be a low-risk potential public health problem, even though it should be monitored.

Diarrhoeal diseases
Outbreaks of diarrhoea do occur, especially during heavy rainfalls and where water supply and sanitation facilities are poor. The last diarrhoeal outbreak was in 2006 and the causative parasite was Cryptosporidium spp., which is transmitted through ingestion of contaminated food.

Public education on prevention of food and water contamination and vigilance, especially during heavy rains, is continuing. Cases of fatalities can occur, especially with delayed diagnosis and in malnourished and HIV-positive children. Diarrhoea is a notifiable disease in Botswana.

Other diseases
Thirty three cases of influenza A H1N1 were reported in 2009.

One case of polio was confirmed in Ngami district in 2005.