A review of foot-and-mouth disease status and control measures in Botswana.

Foot-and-mouth disease (FMD), an economically important disease of livestock, is endemic in Botswana. The country has been affected by this disease since the early 1930s, and FMD virus (FMDV) continues to circulate in both domestic and wild animal populations. Botswana is affected by the Southern African Territories (SAT1-3) of FMDV. Up to 80% of the income in the agricultural sector in Botswana is derived from the beef production, and about 70% of Botswana's beef exports go to the European Union (EU) market. Thus, trade restrictions caused by FMD outbreaks may result in declines in revenue. In this review, the FMD status of Botswana from 2006 to 2022 is discussed. During the report period, SAT2 was responsible for 80 out of a total of 87 FMD outbreaks, while SAT1 was responsible for 7 out of 87 outbreaks. These outbreaks were a result of SAT1 topotype I and SAT2 topotypes I, II, and III. There were no outbreaks associated with serotype SAT3 over the review span, suggesting absence of this serotype in the country, although it is still maintained in vaccines formulated for use in Botswana. Most of the outbreaks reported in this review occurred in the North West district of Botswana; an area that is heavily populated with cloven hooved wildlife. This highlights the role of wildlife-domestic animal interaction in FMD spread and maintenance. The Food and Agriculture Organization (FAO) of the United Nations has created a progressive control pathway for FMD (PCP-FMD) for the global elimination of FMD to reduce FMD-related losses. This review highlights how Botswana takes part in the PCP-FMD by putting in place control measures such as surveillance and vaccination. The review also touches on the disease control challenges such as limitations to separation of livestock with populations of buffaloes and lapses in livestock vaccination which contribute to maintenance of FMDV circulation in Botswana.

A retrospective longitudinal study of animal and human rabies in Botswana 1989-2006.

A longitudinal study of animal and human rabies covering 18 years from 1989 to 2006 was retrospectively conducted in order to highlight the epidemiological features and trends of the disease in Botswana. Over the 18-year period, a total of 4 306 brain specimens collected from various species of animals including human beings with clinical signs consistent with rabies were submitted to the National Veterinary Laboratory in Gaborone for confirmatory diagnosis. Of the samples submitted, 2419 cases were found to be positive for lyssavirus antigen; this presents an overall prevalence rate of 56.18 +/- 1.48%. About 85.7% (2 074/2 419) of the cases were from domestic animals, 14.2% (343/2 419) cases were from wild animals and two cases (0.1%) were from human beings. During the first half of the study (1989-1997) the prevalence rate of the disease was estimated at 62.79 +/- 1.85% (1645/2620 positive) whereas during the second half (1998-2006) it was estimated at 45.91 +/- 2.38% (774/1686 positive) and the difference between the two estimates was statistically, highly significant (delta % = 16.88, SE(95) diff % = 3.015, SD = 5.599; P < 0.001). Ruminant rabies accounted for 79.99% (50.92% bovine, 928.40% caprine and 0.67% ovine) whereas canine (domestic dog) and feline (domestic cat) accounted for 16.01 and 0.87%, respectively. Equine rabies accounted for 3.13% with 1.35 and 1.78%, respectively, for horses and donkeys. Jackal rabies accounted for more than 60% of the total cases in wild animals. These findings are discussed in relation to the previous epidemiological situation of the disease (1979-1988), its socio-economic impact, monitoring and control in Botswana.

A serological survey of African horse sickness in Botswana.

A retrospective serological survey of African horse sickness (AHS) in Botswana covering a 10-year period (1995-2004) is reported. The survey involved horses showing clinical symptoms of the disease; the horses had not been vaccinated against AHS. Over the period surveyed, serological evidence suggestive of infection with AHS virus (AHSV) was found in 99 clinical cases out of which 41.4% (41/99) cases were found during the 1st half (1995-1999) and 58.6 % (58/99) cases were found in the 2nd half of the survey period (2000-2004). These serological findings are discussed in relation to AHSV serotypes isolated from diseased horses in Botswana before and during the period of this serological survey.

A serological survey for antibodies to foot-and-mouth disease virus in indigenous Tswana goats and sheep in Kasane, Maun and Shakawe districts in northwestern Botswana.

A serological survey was conducted in apparently healthy, unvaccinated indigenous Tswana goats and sheep in Kasane, Maun and Shakawe districts in northwestern Botswana in order to determine in these animals, the levels of exposure to the South African Territories (SAT) serotypes: SAT 1, SAT 2 and SAT 3 of foot-and-mouth disease virus (FMDV). A total of 250, 142 and 134 goat sera originating respectively from Kasane, Maun and Shakawe districts were tested for FMDV antibodies against the three SAT serotypes by the liquid phase blocking enzyme-linked immunosorbent assay and 26 of 250 (10.4%), 5 of 142 (3.5%) and 18 of 134 (13.4%) were positive either to SAT 1 or SAT 3, or to both serotypes. None of the goats' sera was positive to SAT 2 serotype. All sheep sera (n = 9) tested negative against all three serotypes of the virus. The findings are discussed in relation to results of other serological surveys carried out elsewhere.

Re-emergence of foot-and-mouth disease in Botswana.

The re-emergence of foot-and-mouth disease (FMD) in Botswana is reported. The disease outbreak occurred in the Matsiloje Extension Area of Francistown veterinary district situated in the northeastern part of the country in an Office International des épízooties (OIE) recognized FMD free zone without vaccination. The disease affected cattle only and did not spillover into sheep and goats resident in the same extension area, as demonstrated by lack of seroconversion to FMD when tested. The virus isolate associated with the outbreak was identified as FMD virus; Southern African Territories (SAT) type SAT-2. The disease outbreak is discussed in relation to FMD outbreaks that have occurred previously within and outside Botswana.

A severe case of contagious ecthyma in Tswana goats.

The first severe case of caprine contagious ecthyma (parapox) in Tswana goats is described from Botswana. Affected animals were indigenous adult Tswana goats. The case involved a flock of 12 goats of which 4 (33.3%) were very severely affected but none died. The lesions were confined to the head and included swollen lips, swollen submandibular lymph nodes, gingivitis, glossitis, ulceration on lip and gum mucosae and scab formation on ulcerated areas. No lesions were found on other parts of the body. This case was clinically indistinguishable from bluetongue.

Antibodies to Newcastle disease virus in the sera of indigenous chickens in Oodi, Kgatleng, Botswana.

A serological survey was conducted to determine the prevalence of antibodies to Newcastle disease virus in apparently healthy and unvaccinated adult indigenous chickens. Haemagglutination inhibiting antibodies to Newcastle disease virus were found in the sera of 51 out of 89 (57.3%) chickens sampled.

Experimental trials with a thermostable Newcastle disease virus (strain I2) in commercial and village chickens in Tanzania.

Antibody responses in indigenous village and commercial chickens vaccinated with 12 thermostable Newcastle disease (ND) vaccine and protection levels against challenge with a virulent field isolate were determined. The antibody response of village chickens vaccinated by eye drop revealed that 30, 60 and 90 days after primary vaccination, the mean log2 HI titres were 6.1, 5.4 and 3.6, respectively, whereas for commercial chickens, the antibody response after 14, 30 and 90 days were 8.2, 5.1 and 4.2, respectively. Village chickens vaccinated orally via drinking water had mean log2 HI titres of 3.4 after 30 days. After booster vaccination, the mean HI titre was 5.4 and 3.3 after 30 and 60 days post-secondary vaccination (i.e. 60 and 90 days after primary vaccination). Antibody response of mean log2 HI titres of 2.6 was recorded 30 days after primary vaccination orally through food; 30 and 60 days after secondary vaccination (i.e. 60 and 90 days after primary vaccination), mean log2 HI titres were 5.3 and 3.2, respectively. All commercial and village chickens vaccinated by eye drop survived the challenge trial whereas village chickens vaccinated through drinking water and food had protection levels of 80% and 60% 30 days after primary vaccination, respectively. However, 30 days after booster vaccination, the protection level was 100%. At 60 days after secondary vaccination, the protection level dropped again to 80% for chickens vaccinated orally. All control chickens used in the challenge trials developed clinical ND and died 3-5 days after inoculation with the virulent virus. Supported by laboratory findings, I2 strain of NDV seemed to be avirulent, immunogenic and highly protective against virulent isolates of NDV. It may be a suitable vaccine to use in village chickens to vaccinate them against ND in rural areas.

Serological evidence of the occurrence of enzootic bovine leukosis (EBL) virus infection in cattle in Tanzania.

Antibodies specific to bovine leukosis (leukemia) virus (BLV) were examined by enzyme-linked immunosorbent, assay (ELISA) in 2,849 serum sample from exotic/improved and indigenous cattle originating from 6 regions of Tanzania, 2,047 from dairy cattle and 802 from beef cattle. An overall infection rate (prevalence) of approximately 36% was detected. The infection rates were 41% and 21.4% in dairy and beef herds respectively. In the dairy herds the infection rate varied from herd to herd. The possible sources of infection and methods of spread within Tanzania are discussed.

Bovine viral diarrhoea virus infection in cattle, sheep and goats in northern Tanzania.

Virological and serological investigations were carried out in cattle, sheep and goats raised in the northern part of Tanzania in order to explore the possibility of bovine viral diarrhoea (BVD) virus cycling within these animal species. Two noncytopathogenic BVD virus isolates (A4/5/Tan86 and A4/10/Tan86) were obtained from sera sampled from inapparently infected indigenous (zebu) cattle originating from Kiteto district in Arusha region. No BVD virus was isolated from any of the sheep or goat sera. Seroepidemiological investigations revealed widespread prevalence of neutralising antibodies to BVD virus not only in cattle but also in sheep and goats. The seropositive rates are discussed in relation to previous observations in Tanzania and other parts of the world and to the livestock husbandry practices in northern Tanzania.